JPH07325317A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide an inexpensive liquid crystal display device of high quality by providing a specified wiring pattern on a leader wire for leading a scanning signal line from a panel display pixel part with the scanning signal line arranged up to the connection terminal part. CONSTITUTION:A space between the panel display pixel part 211 for the liquid crystal panel 110, where a pixel electrode, the scanning signal line, a data signal line and a TFT(thin film transistor) are arranged and the connection terminal part 21 for the liquid crystal panel 110, to which the output of a scanning driver 2 is connected is connected by the leader wire 120 for the scanning signal line. The leader wire 120 is provided with a wire lead-round part 122 adjusting a wire length, the falling characteristic of the scanning signal in the scanning signal line is set so as to have a large time constant. In this case, a pad 121 for the leader wire 120 functions as a part for firmly connecting the output wire of the scanning driver 2 to the leader wire.

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,
In particular, the present invention relates to an active matrix type liquid crystal display device used for displaying television images and the like.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing the structure of a conventional active matrix liquid crystal display device, and FIG.
FIG. 9A is a diagram showing a panel display picture element portion in the liquid crystal panel of the liquid crystal display device and a connection terminal portion with a scan driver in the liquid crystal panel, and FIG. 9B is a diagram showing scanning signal lines from the panel display picture element portion. Showing the wiring for drawing out the scanning signal line for drawing out to the connection terminal portion, FIG. 10 is a view showing the configuration of the pixel electrode plate constituting the liquid crystal panel, and FIG. 11 is a view for explaining the operation of the liquid crystal display device. It is a signal waveform diagram.

In FIG. 1, reference numeral 201 denotes an active matrix type liquid crystal display device having a liquid crystal panel 1 for displaying an image based on a video signal. The liquid crystal panel 1 is provided between a pixel electrode plate 1a and a counter electrode plate 1b. Liquid crystal layer (not shown)
Are arranged.

As shown in FIG. 10, the pixel electrode plate 1a is arranged in a matrix on a substrate 11 and has a plurality of pixel electrodes 12a to 12d (hereinafter, referred to as pixel electrode 1) for driving liquid crystals.
2 is also abbreviated. ), Data signal lines 14a and 14b for supplying a video signal to each pixel electrode 12 (hereinafter also abbreviated as data signal line 14), and a plurality of scanning signal lines provided for each predetermined number of pixel electrodes. Switching which is connected between 13a and 13b (hereinafter also abbreviated as scanning signal line 13) and each pixel electrode and a data signal line, and whose conduction and non-conduction are controlled by a scanning signal from the scanning signal line. And the elements 15a to 15d (hereinafter also abbreviated as switching element 15).
Is composed of a TFT (thin film transistor).

Here, each scanning signal line 13 of the pixel electrode plate 1a in the liquid crystal panel 1 is connected to the scan driver 2. The scan driver 2 has a shift register, and thereby a scan signal is transmitted to each scan signal line 1
It is a circuit for sequentially outputting to 3. Further, each data signal line 14 of the pixel electrode plate 1 a is connected to the segment driver 3. The segment driver 3 receives a video signal via a video signal inverting circuit 4 that inverts the signal level of the video signal, samples this video signal, and outputs a data signal for one horizontal scanning line to each data signal line 14 It is a circuit that outputs to.

In addition, the pixel electrode 1 of the liquid crystal panel 1
2, scanning signal line 13, data signal line 14, and TFT1
The panel display picture element portion 211 in which 5 is arranged and the connection terminal portion 212 of the liquid crystal panel 1 to which the output of the scan driver 2 is connected are connected by the lead wiring 220 of the scanning signal line. The lead-out wiring 220 comprises a pad portion 221 for fixing the output wiring of the scan driver 2 and a wiring portion 22 which constitute the connection terminal portion 212.
2 and.

On the other hand, the counter electrode plate 1b has a counter electrode 7, and a counter voltage serving as a reference of the data signal is always applied to the counter electrode 7 by a counter voltage application circuit 6. ing. Then, the scan driver 2, the segment driver 3, and the video signal inverting circuit 4
The timing control circuit 5 based on the synchronization signal separated from the video signal.
Is controlled by.

Cdg16a to Cdg16d are capacitors between the pixel electrodes 12a to 12d and the scanning signal line 13, and Clg17a to Clg17d are pixel electrodes 12a.
It is the capacitance between 12d and the counter electrode plate 1b.

Next, the operation will be described.

Scan signals are sequentially output to the respective scan signal lines from the scan driver 2 with their rising timings delayed by the horizontal scanning period TH. For example, the scanning signals A and B are output to the adjacent scanning signal lines 13a and 13b as shown in FIGS. Then, the scanning signal is repeatedly sent to each scanning signal line 13 for each vertical scanning period TV.

The video signal D (FIG. 11 (d)) is inverted by the video signal inversion circuit 4 and output to the segment driver 3. Then, the segment driver 3
The video signal E (FIG. 11E) is sampled for one horizontal scanning line for each horizontal scanning period TH, and the data signal F (FIG. 11F) obtained thereby is output to each data signal line 14. At this time, a constant level of the counter voltage C (FIG. 11C) is applied to the counter electrode 7.

Here, when the TFT 15 is turned on by the scanning signal from the scanning signal line 13, the data signal on the data signal line 14 is sent to each pixel electrode 12 via the TFT 15, and thereby the scanning signal line 13 is sent. A voltage that is the difference between the potential of the pixel electrode and the counter voltage is applied to the liquid crystal on the corresponding pixel electrode 12. Moreover, after the horizontal scanning period TH is passed and the TFT 15 is cut off, this applied voltage is held by the capacitance of the liquid crystal layer or the like until the TFT 15 becomes conductive again after the vertical scanning period TV.

Therefore, as shown in FIG. 11G, each pixel of the liquid crystal corresponds to the video signal not only in the horizontal scanning period TH in which the TFT 15 is conducting but also in the entire vertical scanning period TV thereafter. The voltage G to be applied is held.

The operation of transferring data to such a pixel is
By being performed on all scanning signal lines, 1
The display image for the screen is completed.

However, as shown in FIG.
Inside, there is a capacitance Cg between the pixel electrode 12 and the scanning signal line 13.
Since d16 exists, when the scanning signal input to the TFT 15 is switched from the H level to the L level, the capacitance Clc17 of the liquid crystal between the pixel electrode 12 and the counter electrode 7,
Due to the ratio of the capacitance Cgd16 between the pixel electrode and the scanning signal line, as shown in FIG. 11 (g), the voltage G generated by charging the liquid crystal is pulled to the L level of the scanning signal by ΔV. Generally, this pull-in amount ΔV is obtained by the following equation.

[0016]

[Equation 1]

Therefore, the counter voltage C (FIG. 11C) applied to the counter electrode 7 by the counter voltage application circuit 6 is normally set to a voltage lower than the offset voltage from the data signal by ΔV. .

Further, when the liquid crystal is driven by direct current, the life is shortened. Therefore, the video signal E (FIG. 11) inputted to the segment driver 3 by the video signal inverting circuit 4 shown in FIG.
In (e), the polarity is inverted for each vertical scanning period TV,
Further, in order to make the flicker hard to see, the polarity of the video signal is inverted every horizontal scanning period TH by the circuit 4 so that the liquid crystal is AC-driven.

Here, the pull-in amount ΔV of the liquid crystal applied voltage by the scanning signal is as shown in FIG. 3B when the scanning signal is not delayed, that is, when the trailing edge of the scanning signal is steep. The voltage ΔV1 obtained by the equation (1)
Just pulled in. Further, when the scanning signal is delayed, that is, when the trailing edge of the scanning signal is gentle,
As shown in (d), when the scanning signal is switched from the H level to the L level, the voltage charged in the liquid crystal is drawn to the L level of the scanning signal, but the switching of the scanning signal from the H level to the L level is delayed. Due to the delay, the TFT 15 does not shut off immediately, and the voltage charged in the liquid crystal is pulled to the L level of the scanning signal, but the TFT
The liquid crystal is charged via 15. Therefore, the pull-in amount ΔV of the liquid crystal applied voltage due to the scanning signal is as shown in FIG.
As shown in (d), the voltage ΔV1 obtained by the equation (1)
Which is smaller than ΔV2.

[0020]

However, due to the increase in the size and definition of liquid crystal display devices and the increase in the number of data signal lines, the number of scanning signal lines, and the number of pixels, the number of pixels in the liquid crystal panel is increased. Scan signal delay time due to difference in electrode position,
In other words, the variation in the time required for the fall of the scanning signal becomes large, so in the conventional liquid crystal display device, the pull-in of the liquid crystal applied voltage due to the scanning signal greatly varies within the panel, and in-plane unevenness of contrast occurs. Alternatively, flicker may occur even when a DC voltage is applied to the liquid crystal, resulting in a decrease in reliability.

Therefore, the scanning signal line is thickened at the sacrifice of the aperture ratio, or the material of the scanning signal line is changed to a low resistance one at the cost and yield, so that the pixel of the scanning signal delay time The variation due to the position of was reduced.

For example, a flat panel display 1
992 (Published by Nikkei BP, edited by Nikkei Microdevices, 1
Issued November 19, 991) 160-164
In the page, as a measure against the above problem, a method of forming the scanning signal line with a low resistance material such as Al (aluminum) or reducing the parasitic capacitance Cgd of the TFT is proposed.

However, in the method of forming the scanning signal line with a low resistance material, the effect due to the reduction of the scanning signal line resistance is almost eliminated in a large liquid crystal panel of 8 inches or more.

Regarding the reduction of the parasitic capacitance Cgd of the TFT, Cgd and C existing in the conventional TFT are described in the above literature.
Since the two variable capacitances lc adversely affect the screen quality, a large capacitance auxiliary capacitance is added to the pixel to absorb the variable capacitance. However, the electrode for forming this auxiliary capacitance has an opening. The rate will be reduced.

Therefore, it has been proposed to use a so-called self-aligned TFT in which the gate electrode is used as a photomask, whereby the overlap between the gate electrode and the drain electrode can be reduced and the parasitic capacitance Cgd can be surely reduced. . However, in the method using the self-aligned TFT, it is necessary to change the configuration of the TFT which is a switching element.

The present invention has been made in order to solve the above problems, and sacrifices the aperture ratio or changes the material of the scanning signal line to a low resistance material even for a panel having a large scanning signal delay. It is an object of the present invention to provide a high-quality and inexpensive liquid crystal display device without causing a change in the structure of the TFT which is a switching element.

[0027]

A liquid crystal display device according to the present invention includes a plurality of pixel electrodes for driving liquid crystal, a data signal line for supplying a video signal to each pixel electrode, and a predetermined number of pixel electrodes. An active matrix having a plurality of scanning signal lines provided in each pixel and a switching element connected between each pixel electrode and a data signal line and controlled to be conductive or non-conductive by a scanning signal from the scanning signal line. System liquid crystal panel, and a scan driver that sequentially outputs a scanning signal to each of the scanning signal lines, the liquid crystal panel including a connection terminal portion connected to the output of the scan driver, the pixel electrode, and the scanning signal. A line, a data signal line, and a lead-out wiring that is drawn out from the panel display picture element portion where the switching element is arranged to the connection terminal portion and serves as a scanning signal transmission path, Out wiring, in a part thereof, which has a large and wiring patterns of the time constant the transfer characteristic of the scanning signal from the scan driver, the object is achieved.

In the liquid crystal display device according to the present invention, a plurality of pixel electrodes for driving the liquid crystal, a data signal line for supplying a video signal to each pixel electrode, and a plurality of pixel electrodes provided for each predetermined number of pixel electrodes. An active matrix type liquid crystal panel having a scanning signal line and a switching element which is connected between each pixel electrode and a data signal line and whose conduction / non-conduction is controlled by a scanning signal from the scanning signal line is provided. In addition, a scan driver that sequentially outputs a scan signal to each of the scan signal lines is provided, and the scan driver has a scan signal processing circuit that makes the fall change of the scan signal gradual. Therefore, the above object is achieved.

The liquid crystal display device according to the present invention includes a plurality of pixel electrodes for driving the liquid crystal, a data signal line for supplying a video signal to each pixel electrode, and a plurality of pixel electrodes provided for each predetermined number of pixel electrodes. An active matrix type liquid crystal panel having a scanning signal line and a switching element which is connected between each pixel electrode and a data signal line and whose conduction / non-conduction is controlled by a scanning signal from the scanning signal line is provided. At the same time, the variable power supply circuit is provided with a variable power supply circuit capable of generating an ON potential for making the switching element conductive, and a scan driver for sequentially supplying the output of the variable power supply circuit as a scanning signal to each scanning signal line. The output potential thereof has a circuit configuration that attenuates in synchronization with the falling timing of the scanning signal, whereby the above object is achieved.

[0030]

According to the present invention, the leading wiring serving as the transmission path of the scanning signal for leading the scanning signal line from the panel display picture element portion of the liquid crystal panel to the connection terminal portion with the scanning driver is provided with the scanning signal from the scanning driver. Since the structure has a wiring pattern with a large time constant in the transfer characteristic of, the time required for the fall of the scanning signal increases uniformly for all the picture elements in the panel display picture element part. In addition, it is possible to reduce unevenness on the screen caused by variations in the time required for the falling of the scanning signal in the panel display picture element portion.

That is, the increase amount of the liquid crystal applied voltage due to the change in the falling edge of the scanning signal decreases as the time required for the falling edge increases. By increasing the number of picture elements, it is possible to reduce the variation in the amount of pull-in of the liquid crystal applied voltage due to the variation in the time required for the fall. As a result, even for a panel having a large delay of the scanning signal, the configuration of the TFT, which is a switching element, is further changed without sacrificing the aperture ratio or changing the material of the scanning signal line to a low resistance material. It is possible to obtain a high quality and inexpensive liquid crystal display device.

According to the present invention, since the scan driver for sequentially outputting the scan signal to each scan signal line is provided with the scan signal processing circuit for gradually changing the fall of the scan signal, the scan signal is processed. The time required for the falling edge of is uniformly increased for all the picture elements in the panel display picture element section, and as a result, in the same way as above, on the screen generated due to the difference in the time required for the falling of the delay signal. Can be reduced, and a liquid crystal display device of high quality and inexpensive can be obtained as in the above.

In the present invention, a variable power supply circuit capable of generating an ON potential for making a switching element conductive,
A scan driver that sequentially supplies the output of the variable power supply circuit as a scan signal to each scan signal line, and a circuit configuration in which the output potential of the variable power supply circuit is attenuated in synchronization with the falling timing of the scan signal. Therefore, the time required for the falling edge of the scanning signal increases uniformly for all the picture elements in the panel display picture element section, which causes a difference in the time required for the falling edge of the delay signal to occur on the screen. Can be reduced, and a liquid crystal display device of high quality and inexpensive can be obtained as in the above.

[0034]

EXAMPLES Examples of the present invention will be described below.

Example 1. FIG. 1 is a diagram for explaining a configuration of an active matrix type liquid crystal display device according to a first embodiment of the present invention, and FIG. 1A is a connection portion of a liquid crystal panel of the device with a scan driver. FIG. 1 (b) is a plan view showing the pattern of the lead-out wiring of the scanning signal line in the liquid crystal panel, and corresponds to FIG. 9 used in the description of the prior art. 2 is a signal waveform diagram for explaining the operation of the liquid crystal display device of the first embodiment,
FIG. 3 is a signal waveform diagram for explaining the principle of pulling in a liquid crystal applied voltage by a scanning signal in the liquid crystal display device.

In the figure, reference numeral 101 denotes an active matrix type liquid crystal display device of this embodiment, which has a liquid crystal panel 110 for displaying a television image. The liquid crystal panel 110 is the conventional one shown in FIG. Like the liquid crystal display device 201, the liquid crystal display device 201 has a configuration in which a liquid crystal layer (not shown) is arranged between the pixel electrode plate 1a and the counter electrode plate 1b. In FIG. 1, the segment driver 3, the video signal inverting circuit 4, the timing control circuit 5, the counter voltage applying circuit 6 and the like are omitted.

That is, the pixel electrode plates 1a are arranged in a matrix on the substrate 11, as shown in FIG.
It has a large number of pixel electrodes 12 constituting each pixel (picture element), and on this substrate 11, horizontal scanning signal lines 13 and vertical data signal lines 14 are arranged in a grid pattern. It is arranged so as to be located between each pixel electrode 12.

A TFT 15 is arranged at each intersection of the scanning signal line 13 and the data signal line 14. This TFT 15 is actually the scanning signal line 1
3 is a switching transistor formed by forming a semiconductor thin film on the scanning signal line as a gate terminal, the source terminal of which is connected to the data signal line 14 and the drain terminal of which is connected to the pixel electrode 12. That is, in each pixel of the liquid crystal panel, when the scanning signal is sent to the scanning signal line 13 and the TFT 15 thereof becomes conductive, the data signal on the data signal line 14 intersecting with the scanning signal line 13 is applied to the pixel electrode 12. It is structured to be. In addition, each pixel electrode 12
The data signal thus applied can be held by the capacitance of the liquid crystal layer even after the TFT 15 is cut off.

As shown in FIG. 8, the counter electrode plate 1b has a counter electrode 7 formed on one surface of a substrate 11, and the counter electrode 7 is provided on each pixel electrode 12 on the pixel electrode plate 1a side. Is a common electrode for. Further, each scan signal line 13 of the pixel electrode plate 1 a in the liquid crystal panel 1 is connected to the scan driver 2, and each data signal line 14 is connected to the segment driver 3.

Then, in this embodiment, the liquid crystal panel 110 is used.
Of the panel display picture element portion 2 in which the pixel electrode 12, the scanning signal line 13, the data signal line 14, and the TFT 15 are arranged.
11 and a connection terminal portion 212 of the liquid crystal panel 110 to which the output of the scan driver 2 is connected are connected by a lead wire 120 for a scan signal line, and the lead wire 120 serves to increase the wire length. Wire routing part 1
22 is provided so that the falling characteristic of the scanning signal on the scanning signal line 13 has a large time constant. Reference numeral 121 denotes a pad of the lead wiring 120, which is a portion for firmly connecting the output wiring of the scan driver 2 to the lead wiring.

Next, the operation will be described.

First, the basic operation of the liquid crystal display device will be briefly described with reference to FIGS.

When a video signal received by a tuner circuit (not shown) is input to the segment driver 3 via the video signal inverting circuit 4, the segment driver 3
Outputs the data signal of one horizontal scanning line to each data signal line 14 by sampling the video signal from the video signal inverting circuit 4.

On the other hand, the scan driver 2 sequentially outputs the scanning signal to each scanning signal line 13 while shifting the scanning signal for each horizontal scanning period TH by the shift register constituting the scanning driver 2, and repeats this for each vertical scanning period TV. . Here, the scanning signal input to the liquid crystal panel 110 is changed in level at the gate end of the TFT 15 by the wiring routing portion 122 of the extraction wiring 120 that draws the scanning signal line from the panel display picture element portion 211 to the connection terminal portion 212. Has become loose.

As described above, in the liquid crystal panel 110, the scan signal is scanned by the scan driver 2 and the scan signal is supplied to the scan signal line 1.
3 and all the TFTs 15 on the scanning signal line 13 to which the scanning signal is output are rendered conductive, whereby a data signal for one horizontal scanning line from the segment drive 3 is transmitted via the data signal line 14 and the TFT 15. It is applied to the pixel electrode 12. By repeating this operation for each horizontal scanning period TH, an image for one screen is displayed.

In the above operation, the video signal applied to each pixel electrode 12 is sequentially inverted in polarity by the video signal inverting circuit 4, and the counter electrode 7 of the counter electrode plate 1b of the liquid crystal panel 1 is reversed. A counter voltage, which serves as a reference for the video signal of the pixel electrode 12, is always applied to the counter voltage applying circuit 6. Therefore, the polarity reversal of the video signal by the video signal reversing circuit 4 is performed with the counter voltage as a reference, and the liquid crystal is AC-driven by this.

Next, the level change of the scanning signal on the scanning signal line will be described in detail with reference to the signal waveform diagram of FIG.

From the scan driver 2, FIG.
As shown in (a) and (b), a scanning signal having a signal waveform with no delay in rising and falling is output and input to the liquid crystal panel 110. In the present embodiment, as shown in FIG. As shown in FIG.
2 has a wiring routing part 122, the rising and falling changes of the scanning signal at the input end of the panel display picture element part 211 are slightly gradual as shown in FIGS. 2 (a) and 2 (c). It will be

That is, the scanning signals A1 and B1 are adjacent scanning signal lines 1 in the panel display picture element portion 211, for example.
When sequentially output to 3a and 13b, on the input side of the scanning signal line (first line) 13a, that is, in the portion near the lead wire 120, the scanning signal A1 begins to rise at time t1 and becomes H level after a lapse of a predetermined time. Scan signal A1 at t2
Starts falling and returns to the L level after a predetermined time has elapsed. The scanning signal line 13a is at the H level during the period from time t1 to t2. Then, at time t5 after the elapse of the vertical scanning period TV from the time t1, the rising of the scanning signal is started again to the H level, and this is repeated every vertical scanning period TV.

On the input side of the next scanning signal line (second line) 13b, as shown in FIG. 2C, the scanning signal B1 rises at time t3 which is later than the first scanning line by the horizontal scanning period TH. First, the scanning signal B1 becomes H level after a lapse of a predetermined time, the scanning signal B1 starts to fall at time t4, becomes L level after the lapse of a predetermined time, and the scanning signal rises again at time t7 after the vertical scanning period TV has elapsed from the time t3. It becomes H level for the first time. Then, the scanning signal line 1 for the third and subsequent lines
Similarly to 3, the same scanning signal is output with a delay of the horizontal scanning period TH in the same manner as described above.

At this time, in the open side of the scanning signal lines 13a and 13b, that is, in the portion far from the lead wiring,
The rising and falling changes of the scanning signal are shown in FIG.
As shown in (b) and (d), the change is more gradual than the change on the input side.

By the way, in the case where the lead-out wiring of the scanning signal line does not have the wiring leading portion like the conventional liquid crystal display device 201, a picture close to the input end of the scanning signal of the panel display picture element portion 211 is usually used. In the pixel, the level change of the scanning signal is abrupt, but in the pixel far from the input end of the scanning signal of the panel display picture element portion 211, the level change of the scanning signal becomes slow.

When the panel is driven in this state, the liquid crystal applied voltage is pulled in by the scanning signal, as shown in FIG. 3B in the picture element in the portion where the level change of the scanning signal is sharp.
Only the voltage ΔV1 obtained by the equation (1) is drawn. On the other hand, even in the part of the picture element where the level change of the scanning signal is slow, when the scanning signal is switched from the H level to the L level as shown in FIG. 3D, the voltage charged in the liquid crystal becomes L of the scanning signal. However, it takes time to switch the scanning signal from H level to L level.
The TFT 15 does not shut off immediately. Therefore, even though the voltage charged in the liquid crystal is drawn to the L level of the scanning signal, the liquid crystal is charged through the TFT 15, and the drawing amount of the voltage applied to the liquid crystal by the scanning signal is as shown in FIG.
As described above, the value ΔV2 becomes smaller than the voltage ΔV1 obtained from the equation (1). Therefore, in order to increase the size and definition of the liquid crystal panel, if the variation in the pull-in amount of the liquid crystal applied voltage due to the scanning signal in the liquid crystal panel becomes large, there arises the problem of in-plane contrast unevenness.

On the other hand, in this embodiment, as described above, the lead wire 120 for the scanning signal line of the liquid crystal panel is laid out to increase the resistance of the leading portion of the scanning signal line. The time required for the level change of the scanning signal in each part is slightly increased for both the picture element near the part and the picture element far from the input end of the scanning signal.

In this case, in the picture element in the part far from the input end of the scanning signal of the panel display picture element portion, even if the level change of the scanning signal becomes gentle, the scanning signal becomes H level even if it becomes a little more gentle. During the period when the scanning signal of FIG. 3C is outputting the TFT conducting voltage during the switching from the low level to the L level, the voltage slightly increases, and the voltage drawn by the scanning signal during the period of outputting the TFT conducting voltage. 3 minutes, the liquid crystal is sufficiently charged, and as shown in FIG. 3D, only the change in the scanning signal during the period in which the scanning signal cuts off the TFT,
The liquid crystal applied voltage is not drawn. Therefore, the pull-in amount of the liquid crystal applied voltage by the scanning signal does not change much.

On the other hand, in the picture element of the panel display picture element portion near the input end of the scanning signal, when the level change of the scanning signal changes from the steep state to the slightly gradual state, the scanning signal becomes H level.
During the switching from the level to the L level, there is almost no period during which the scanning signal of FIG. 3A outputs the TFT conduction voltage, and then there occurs a period during which the TFT conduction voltage is output. For this reason, the liquid crystal is hardly charged when the scan signal falls, and the liquid crystal is slightly charged, and the amount of pulling in the liquid crystal applied voltage by the scan signal largely changes. As a result,
The pull-in amount of the liquid crystal applied voltage in the picture element in the part near the scanning signal input end of the panel display picture element is the pull-in amount of the liquid crystal applied voltage in the picture element in the part far from the scan signal input end of the panel display picture element part. It is a value close to.

As described above, by devising the pattern of the lead-out wiring of the scanning signal line 13 of the liquid crystal panel 1 to increase the time required for the level change of the scanning signal in the panel display picture element portion as a whole, Even if there is a large variation in the time required to change the level of the scanning signal within the panel, the variation in the amount of pulling in the liquid crystal applied voltage due to the scanning signal within the panel will be small.

As described above, when each scanning signal line 13 is sequentially set to the H level by the scanning signal, each TFT 15 connected to the scanning signal line 13 becomes conductive, and the pixel electrode 12 is connected via the TFT 15. The data signal lines 14 are sequentially connected.

Since the liquid crystal panel 110 displays white when no voltage is applied, the video signal inverting circuit 4 is sent from a tuner circuit (not shown).
The video signal F of (f) is inverted in signal level of white display and black display like the video signal G of FIG. 2 (g), and the inversion circuit 4 has a lifespan when the liquid crystal is driven by direct current. Therefore, the polarity of the video signal is inverted every vertical scanning period TV, and the polarity of the video signal is also inverted every horizontal scanning period TH in order to make flicker less visible. Further, the segment driver 3 samples the video signal G of FIG. 2 (g) sent from the video signal inverting circuit 4 by one horizontal scanning for each horizontal scanning period TH at a predetermined sampling pitch, and then performs the next predetermined sampling. In the horizontal scanning period TH, as shown in FIG.
The data signal H of (h) is output to each data signal line 14.

Then, the TFT 15 selected for the scanning signal
A video signal is applied to each pixel electrode 12 via. Even after the TFT 15 is cut off, the next vertical scanning period T
Up to V, as shown in FIG. 2H, data signals for the pixel electrodes 12 connected to the other scanning signal lines 13 via the TFTs 15 are sequentially output to the data signal lines 14. However, once the TFT 15 is cut off like the voltage I in FIG. 2I, the charge of the pixel electrode 12 does not change. The segment driver 3 repeats this operation for each horizontal scanning period TH, and the video signals for each horizontal scanning line are
It is sequentially applied to all pixel electrodes 12 on the liquid crystal panel 110.

While the video signal is sequentially applied to each pixel electrode 12 as described above, the counter voltage application circuit 6 always outputs a constant counter voltage EC, and the pixel electrode 12 and the counter electrode 7 are connected to each other. A voltage difference is applied to the liquid crystal.

The above operation is carried out on all the scanning signal lines, and the image for one screen is displayed.

As described above, in this embodiment, the liquid crystal panel 11 is used.
0 from the panel display picture element section 211 to the liquid crystal panel 110
Of the lead wire 120 for drawing out the scan signal line to the connection terminal portion 212 to which the output of the scan driver 2 is connected,
Since the structure has the wiring routing portion 122 for increasing the wiring length, the time required for the fall of the scanning signal is
All the picture elements in the panel display picture element area are uniformly increased, thereby reducing the unevenness on the screen caused by the variation in the time required for the fall of the scanning signal in the panel display picture element area. You can

That is, since the increase amount of the liquid crystal applied voltage due to the change in the falling edge of the scanning signal becomes smaller as the time required for the falling edge increases, all the time required for the falling edge is reduced. By increasing the number of picture elements, it is possible to reduce the variation in the amount of pull-in of the liquid crystal applied voltage due to the variation in the time required for the fall. As a result, even for a panel having a large delay of a scanning signal, the structure of the TFT, which is a switching element, is changed without sacrificing the aperture ratio or changing the material of the scanning signal line to a low resistance material. It is possible to obtain a high quality and inexpensive liquid crystal display device.

Example 2. 4 is a diagram for explaining a liquid crystal display device according to a second embodiment of the present invention.
4A is a block diagram showing the overall configuration of this liquid crystal display device, and FIG. 4B is a circuit diagram showing the configuration of a scanning signal delay circuit. Further, FIG. 5 is a signal waveform diagram for explaining the operation of the liquid crystal display device of the second embodiment.

In the figure, reference numeral 102 denotes an active matrix type liquid crystal display device of this embodiment.
In the liquid crystal display device 101 of the first embodiment, instead of forming the wiring leading portion in the leading wiring of the scanning signal line, the scanning driver 20 is provided with a scanning signal delay that makes the falling change of the scanning signal gentle. The configuration includes the circuit 21, and the other configurations are the same as those in the first embodiment.

The scanning signal delay circuit 21 includes a scanning signal delay switch 21a connected between its output terminal 22a and the Vdd power supply, and a scanning signal delay switch connected between the output terminal 22a and the Vee power supply. Capacitor 21b
And a scanning signal delay resistor 21c connected in parallel with the capacitor 21b.
On the output side of the scanning signal changeover switch 22 for switching the output of the circuit and the Vee power supply to connect to the scanning signal line.
Are provided for each scanning signal line.

Next, the operation will be described.

In this embodiment also, the basic image display operation of the liquid crystal display device is the same as that of the first embodiment, so its explanation is omitted and the operation of the scan driver for outputting the scan signal will be described below. This will be described using 5.

The scan driver 2 outputs, for example, the scan signals A10 and B10 to each scan signal line by the following operation. First, at time t9, the scanning signal delay switch 2
1a is turned on (FIG. 5 (f)), the ON voltage Vdd is applied to the scanning signal delay capacitor 21b and the scanning signal delay resistor 21c.
Is applied to charge the capacitor 21b. After that, at time t1, the scanning signal changeover switch 22 changes to Vdd.
Then, the scanning signal line 13 becomes H level. At this time, the scanning signal delay capacitor 21b
Is charged, the scan signal output from the scan driver 2 is hardly delayed.

At time t2, the scanning signal delay switch 21a is turned off (FIG. 5 (f)), but since the scanning signal changeover switch 22 is on the Vdd side, the capacitances of the scanning signal delay capacitor 21b and the scanning signal line 13 are set. Is stored in the off voltage Vee through the scanning signal delay resistor 21c.
, The scanning signal line 13 is gradually switched to the L level.

Then, at time t10, the scanning signal changeover switch 22 is changed over to the off voltage Vee side (see FIG. 5).
(E)) The scanning signal line 13 is completely switched to the L level. By this operation, the scan signal A10 output from the scan driver 2 has a steep rise with almost no delay in its rise, but has a gradual fall change.

In this way, by making only the falling change of the scanning signal gradual, the picture element (see FIGS. 5A and 5C) near the input end of the scanning signal and the scanning signal The picture element in the part far from the input end (Fig. 5 (b),
In both cases, the time required for the falling change of the scanning signal in each part is slightly increased. As a result, as described in the first embodiment, even if there is a large variation in the time required to change the level of the scanning signal within the panel, the variation in the amount of pulling in the liquid crystal applied voltage due to the scanning signal within the panel is small. Becomes

Since only the falling change of the scanning signal is made gentle and the rising change of the scanning signal is made steep, it has little influence on the charging of the pixel electrode. Other operations are similar to those of the first embodiment, and the image display operation based on the counter voltage E, the video signals F and G, the data signal H, and the picture element voltage I is performed.

As described above, in the second embodiment, the scan driver 20 for sequentially outputting the scanning signal to each scanning signal line is
Since the scan signal delay circuit 21 is provided to make the fall change of the scan signal gradual, the time required for the fall of the scan signal is uniformly increased for all the picture elements in the panel display picture element section. As a result, similar to the first embodiment, it is possible to reduce the unevenness on the screen caused by the difference in the time required for the falling of the delay signal, and a high quality and inexpensive liquid crystal display device. Can be obtained.

Example 3. FIG. 6 is a diagram for explaining a liquid crystal display device according to a third embodiment of the present invention.
FIG. 6A is a block diagram showing the overall configuration of this liquid crystal display device, and FIG. 6B is a schematic diagram showing the configuration of the scanning signal changeover switch. FIG. 7 is a signal waveform diagram for explaining the operation of the liquid crystal display device of the third embodiment.

In the figure, reference numeral 103 denotes an active matrix type liquid crystal display device of the present embodiment.
Instead of providing the scan signal delay circuit 21 in the scan driver as in the liquid crystal display device 102 of the second embodiment, the variable scan signal ON power supply circuit 8 for generating the TFT ON potential for bringing the TFT 15 into a conductive state, A scan signal OFF power supply circuit 9 for generating a TFT OFF potential for turning off the TFT 15 is provided, and the output of each power supply circuit is switched by the changeover switch 32 in the scan driver 2 corresponding to each scan signal line. The output is provided to each scanning signal line, and the other configuration is the same as that of the second embodiment.

Here, the variable scanning signal ON power supply circuit 8 is set.
Is controlled by the timing control circuit 5 so that its ON signal is attenuated in synchronization with the falling timing of the scanning signal, whereby only the falling change of the scanning signal is made gradual.

Next, the operation will be described.

Also in this embodiment, the basic image display operation of the liquid crystal display device is the same as that of the above-mentioned first embodiment, and therefore its explanation is omitted and the operation of the scan driver for outputting the scan signal will be described below. This will be described using 7.

The scan driver 2 outputs the scanning signals A11 and B11 to each scanning signal line by the following operation.

First, at time t1, the switch 32 is switched to the Vdd side (FIG. 7 (e)), and the scanning signal line 13 becomes H level. At this time, the variable scanning signal ON power supply circuit 8 outputs an ON voltage of a level at which the TFT is conductive to the scan driver 2 (FIG. 7 (f)). At time t2, the voltage output from the variable scanning signal ON power supply circuit 8 to the scan driver 2 is gradually switched from the level at which the TFT conducts to the level at which the TFT shuts off (see FIG. 7).
(F)), the scanning signal line 13 is also gradually switched to the L level (FIG. 7A). Then, at time t9, the scanning signal changeover switch 32 is switched to the off voltage Vee side (FIG. 7E), and the scanning signal line 13 is completely switched to the L level.

Subsequently, time t3 at which the scanning signal line changeover switch 32 of the next scanning signal line 13 is switched to the Vdd side.
By the time, the variable scan signal ON power supply circuit 8 outputs to the scan driver 2 a voltage of a level at which the TFT conducts so that the rising of the next scan signal is not delayed. By this operation, the scan signal output from the scan driver 2 has almost no delay in rising and only in falling.

As described above, only the falling transition of the scanning signal is made gentle so that the picture element (see FIGS. 7A and 7C) near the input end of the scanning signal and the scanning signal The picture element in the part far from the input end (Fig. 7 (b),
In both cases, the time required for the falling change of the scanning signal in each part is slightly increased. As a result, as described in the first embodiment, even if there is a large variation in the time required to change the level of the scanning signal within the panel, the variation in the amount of pulling in the liquid crystal applied voltage due to the scanning signal within the panel is small. Becomes

As in the second embodiment, only the falling change of the scanning signal is made gradual and the rising change of the scanning signal is made steep, so that the charging of the pixel electrode is not affected. small. Other operations are the same as above
And the counter voltage E, the video signals F and G,
An image display operation based on the data signal H and the pixel voltage I is performed.

As described above, in the third embodiment, the TFT 15
The variable scanning signal ON power supply circuit 8 for generating the TFT ON potential for bringing the TFT into the conductive state and the TFT for bringing the TFT 15 into the non-conductive state
A scan signal OFF power supply circuit 9 for generating an FT OFF potential is provided, and the output of each power supply circuit is switched by the changeover switch 32 in the scan driver 2 corresponding to each scan signal line and output to each scan signal line. As well as
Since the variable scanning signal ON power supply circuit 8 is configured such that the ON signal attenuates in synchronization with the falling timing of the scanning signal, the time required for the falling of the scanning signal is
This increases uniformly for all the picture elements of the panel display picture element portion, and as a result, the unevenness on the screen caused by the difference in the time required for the fall of the delay signal is generated as in the first embodiment. It is possible to obtain a high-quality and inexpensive liquid crystal display device that can be reduced.

[0087]

As described above, according to the liquid crystal display device of the present invention, the lead-out wiring for drawing out the scanning signal line from the panel display picture element portion where the scanning signal line is arranged in the liquid crystal panel to the connection terminal portion thereof is provided. Since a part of the structure has a wiring pattern that makes the transfer characteristic of the scan signal from the scan driver have a large time constant, the time required for the fall of the scan signal uniformly increases for all picture elements. As a result, it is possible to reduce unevenness on the screen caused by the difference in time required for the fall of the scanning signal.

As a result, the liquid crystal display device has become larger and more detailed, the number of data signal lines and the number of pixels have increased, and the panel in which the scanning signal is greatly delayed does not sacrifice the aperture ratio. By using a stable scanning signal line material, it is possible to realize a high-quality and inexpensive liquid crystal display device.

Further, according to the liquid crystal display device of the present invention, the scan driver for sequentially outputting the scan signal to each scan signal line is provided with the scan signal processing circuit for making the fall change of the scan signal gentle. Because it has a configuration,
The time required for the falling edge of the scanning signal is uniformly increased for all the picture elements, which can reduce the unevenness on the screen caused by the difference in the time required for the falling edge of the delay signal. As a result, similarly to the above, a high quality and inexpensive liquid crystal display device can be obtained.

Further, according to the liquid crystal display device of the present invention, a power supply circuit capable of generating a potential for making the switching element of each pixel conductive, and an output potential of the power supply circuit as a scanning signal to each scanning signal line. A scan driver that sequentially outputs is provided, and the power supply circuit is configured to attenuate its output potential in synchronization with the fall timing of the scan signal so that the fall characteristic of the scan signal has a large time constant. Therefore, the time required for the falling edge of the scanning signal is uniformly increased for all the picture elements, which can reduce the unevenness on the screen caused by the difference in the time required for the falling edge of the delay signal. As a result, similarly to the above, a high quality and inexpensive liquid crystal display device can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a configuration of a liquid crystal display device according to a first embodiment of the present invention, FIG. 1 (a) is a schematic diagram showing a connection portion of a liquid crystal panel with a scan driver, FIG.
FIG. 6B is a plan view showing a pattern of the lead wiring of the scanning signal line in the liquid crystal panel.

FIG. 2 is a signal waveform diagram for explaining the operation of the liquid crystal display device of the first embodiment.

FIG. 3 is a diagram showing a liquid crystal display device of the above-mentioned embodiment
FIG. 6 is a signal waveform diagram for explaining the principle of pulling in a liquid crystal applied voltage by a scanning signal.

FIG. 4 is a diagram for explaining a liquid crystal display device according to a second embodiment of the present invention, FIG. 4 (a) is a block diagram showing the overall configuration of this embodiment device, and FIG. 4 (b) is a scanning diagram. It is a circuit diagram which shows the structure of a signal delay circuit.

FIG. 5 is a signal waveform diagram for explaining the operation of the liquid crystal display device of the second embodiment.

6A and 6B are views for explaining a liquid crystal display device according to a third embodiment of the present invention, FIG. 6A is a block diagram showing the overall configuration of the device of this embodiment, and FIG. 6B is a scanning diagram. It is a schematic diagram which shows the structure of a signal changeover switch.

FIG. 7 is a signal waveform diagram for explaining the operation of the liquid crystal display device of the third embodiment.

FIG. 8 is a block diagram for explaining the configuration of a conventional liquid crystal display device.

FIG. 9 is a diagram showing a detailed configuration of a conventional liquid crystal display device, FIG. 9 (a) is a schematic diagram showing a connection portion of a liquid crystal panel with a scan driver, and FIG. 9 (b) is a scanning diagram in the liquid crystal panel. It is a top view which shows the pattern of the lead-out wiring of a signal line.

FIG. 10 is a diagram showing a panel display picture element unit in a liquid crystal panel constituting a conventional liquid crystal display device.

FIG. 11 is a signal waveform diagram for explaining the operation of the conventional liquid crystal display device.

[Explanation of symbols]

1,110 Liquid crystal panel 1a Pixel electrode plate 1b Counter electrode plate 2,20 Scan driver 3 Segment driver 4 Video signal inversion circuit 5 Timing control circuit 6 Counter voltage applying circuit 7 Counter electrode 8 Variable scan signal ON power supply circuit 9 Scan signal OFF power supply Circuits 12a, 12b, 12c, 12d Pixel electrodes 13a, 13b Scan signal lines 14a, 14b Data signal lines 15a, 15b, 15c, 15d TFTs (thin film transistors) 21 Scan signal delay circuits 21a Scan signal delay switches 21b Scan signal delay capacitors 21c Scan signal delay resistor 22 Scan signal changeover switch 101, 102, 103 Liquid crystal display device 120 Lead wire 121 Pad part 122 Wiring part 211 Panel display picture element part 212 Connection terminal part

Claims (3)

[Claims] 1. A plurality of pixel electrodes for driving a liquid crystal, a data signal line for supplying a video signal to each pixel electrode, and a plurality of scanning signal lines provided for each predetermined number of pixel electrodes,
An active matrix type liquid crystal panel having a switching element connected between each pixel electrode and a data signal line and having conduction and non-conduction controlled by a scanning signal from the scanning signal line, and each scanning signal line And a scan driver for sequentially outputting a scan signal to the liquid crystal panel. The liquid crystal panel includes a connection terminal portion connected to the output of the scan driver, the pixel electrode, the scan signal line, the data signal line, and the switching element. And a lead-out wiring which is drawn from the panel display picture element portion to the connection terminal portion and serves as a scan signal transmission path. The lead-out wiring has a transfer signal transmission characteristic from the scan driver as a part thereof. A liquid crystal display device having a wiring pattern having a large constant. 2. A plurality of pixel electrodes for driving liquid crystal, a data signal line for supplying a video signal to each pixel electrode, and a plurality of scanning signal lines provided for each of a predetermined number of pixel electrodes.
An active matrix type liquid crystal panel having a switching element connected between each pixel electrode and a data signal line and having conduction and non-conduction controlled by a scanning signal from the scanning signal line, and each scanning signal line And a scan driver that sequentially outputs a scan signal, the scan driver having a scan signal processing circuit that makes the fall change of the scan signal gradual. 3. A plurality of pixel electrodes for driving liquid crystal, a data signal line for supplying a video signal to each pixel electrode, and a plurality of scanning signal lines provided for each predetermined number of pixel electrodes,
An active matrix liquid crystal panel having a switching element connected between each pixel electrode and a data signal line and having conduction and non-conduction controlled by a scanning signal from the scanning signal line; A variable power supply circuit capable of generating an ON potential for setting a state and a scan driver that sequentially supplies an output of the variable power supply circuit to each scanning signal line as a scanning signal are provided. A liquid crystal display device having a circuit configuration that attenuates in synchronization with the falling timing of a signal.