JP2002122840A - Liquid crystal display - Google Patents

Abstract

(57) [Problem] To provide a drive system that moves ionic impurities in a liquid crystal panel by an electric signal and diffuses the ionic impurities throughout the liquid crystal panel to suppress local gradation defects and alleviate extreme display quality deterioration. Liquid crystal display device having the same. SOLUTION: An electric signal including a gate bus line 3 and a source bus line 4 for sandwiching the liquid crystal layer and enclosing the liquid crystal layer and providing an electric signal for moving ionic impurities mixed in the liquid crystal layer. In a liquid crystal display device including two substrates in which a plurality of lines are wired in a display surface, an electric signal generating a Coulomb force for attracting or repelling ionic impurities is regularly applied to each electric signal line. The feature is to give to.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a display device using a liquid crystal.

[0002]

2. Description of the Related Art In a liquid crystal panel, an impurity may be mixed into a liquid crystal layer due to some trouble in a manufacturing process, or an impurity may enter from a peripheral portion of the liquid crystal panel in a use environment of a product. The impurities in the liquid crystal panel
The specific resistance of the liquid crystal material is reduced, and in particular, in the case of the active matrix method, the OFF characteristics of the transistor are deteriorated.

FIG. 8 is a sectional view showing a configuration example of a conventional liquid crystal panel. The liquid crystal panel is composed of two substrates, a TFT side substrate 11 and a CF side substrate 12, and a liquid crystal layer 1 in which a space is maintained between the two substrates by a seal portion 13 and a liquid crystal is sealed.
And 4. The TFT-side substrate 11 has
A TFT (Thin Film Transistor) and a pixel electrode, not shown, are arranged. Further, a color filter, a COM electrode (common electrode) and the like (not shown) are arranged on the CF-side substrate. The liquid crystal layer 14 has a frame portion 15 around the panel and an active area 16 as a display area.
And divided into

Particularly, in the frame portion 15, as described above, there is a possibility that impurities may enter from the peripheral portion of the panel during the manufacturing process or during use, so that a defect in the gradation characteristics is expected. By covering such a frame portion 15 with a light-shielding pattern 17, the influence of a defect of the gradation characteristic generated in the frame portion 15 is prevented from being exerted on the active area 16. However, when the impurity penetrates into the display area and the gradation characteristic deteriorates in a specific portion of the display area, the display quality becomes uneven and the display quality deteriorates. When such a problem occurs, it is attempted to improve the quality of the panel to be manufactured later by strengthening the management of the manufacturing process and changing the design of the liquid crystal panel without rescuing the panel in which the problem has occurred. ing. Further, in order to relieve a liquid crystal panel in which a problem has occurred, the following liquid crystal panel configuration has been proposed.

FIG. 9 is a cross-sectional view showing a configuration example in which an impurity adsorption pattern is provided in the conventional liquid crystal panel of FIG. FIG. 10 is a cross-sectional view schematically showing a state of impurity movement in a conventional liquid crystal panel provided with an impurity adsorption electrode. As shown in FIG. 9, an impurity adsorbing pattern 111 is provided in the frame portion 15 outside the active area 16 to adsorb ionic impurities, thereby reducing ionic impurities in the display area. For example, as shown in FIG. 10, an impurity-adsorbing electrode 112 is provided in the frame portion 15 and an electric signal of several volts (V) is given to move the impurities in the liquid crystal layer 14 in the direction of arrow 113 so that the impurity-adsorbing electrode 112 is moved. 11
2 to be adsorbed.

[0006]

As described above, when a dedicated electrode is provided in a frame portion outside the display area in order to improve a liquid crystal panel in which a defect has occurred, the frame size of the liquid crystal panel becomes large. This is a negative factor for product trends that are moving toward the trend of becoming more and more.

An object of the present invention is to provide a drive system which moves ionic impurities in a liquid crystal panel by an electric signal and diffuses the ionic impurities throughout the liquid crystal panel to suppress local gradation defects and alleviate extreme deterioration of display quality. Liquid crystal display device having the same.

[0008]

According to the present invention, there is provided a liquid crystal display device having an electric signal line for supplying an electric signal for moving and diffusing ionic impurities mixed in a liquid crystal layer.

According to the present invention, by applying an electric signal to move the ionic impurities, the ionic impurities can be diffused throughout the liquid crystal panel to maintain the uniformity on the display surface and to partially maintain the characteristic. It can be avoided that different places occur and the display quality is seriously affected.

Further, in the present invention, a plurality of the electric signal lines are provided in a display surface, and an electric signal generating a Coulomb force for attracting or repelling ionic impurities is regularly applied to each electric signal line. Features.

According to the present invention, the direction of movement of the ionic impurities can be arbitrarily controlled by regularly applying the electric signal to each electric signal line. And local gradation defects can be suppressed, and extreme deterioration of display quality can be alleviated.

Further, the present invention is characterized in that the electric signal line is a signal line provided for use in display.

According to the present invention, by using the pattern used for the display drive signal, it is not necessary to provide a dedicated pattern outside the display area, so that the display quality is important without changing the frame size. It is possible to provide a liquid crystal display device capable of avoiding the influence.

Further, the present invention is characterized in that the electric signal line is provided separately from a signal line provided for use in display.

According to the present invention, by providing a dedicated signal wiring pattern for generating Coulomb force, the restriction on the arrangement of the signal wiring pattern is reduced, and the electric signal lines are brought into contact with the liquid crystal layer and these are connected. Since they can be in close contact with each other, the electric field does not weaken across the insulating layer, and ionic impurities can be more easily moved to obtain an efficient diffusion effect.

Further, the present invention is characterized in that the electric signal is given in a non-display period between each frame display period in a display period.

According to the present invention, the electric signal for generating the Coulomb force is applied to the non-display period between each frame display period, so that the ionic impurities in the liquid crystal layer can be removed without affecting the display. An existing signal wiring pattern such as a bus line provided in a liquid crystal display device can be used as an electrode for generating Coulomb force.

Further, the present invention is characterized in that the electric signal is given in a non-display period when the backlight is not turned on.

According to the present invention, when the liquid crystal display device is started,
The drive signal for generating Coulomb force is turned on when the backlight is not lit, such as at the time of the power saving mode and at the end of the operation.Therefore, compared to the case where the drive signal is generated by interrupting during the display frame period, By turning on the drive signal for a long time (several seconds or more), the ionic impurities can be moved more efficiently and easily, and a higher diffusion effect can be expected.

Further, the invention is characterized in that the backlight is turned off during the non-display period. According to the present invention, since the backlight is turned off during the non-display period between each frame display period, it is a possible effect even when a drive voltage is applied during the non-display period. The effects can be avoided.

[0021]

FIG. 1 is a plan view showing an example of movement and diffusion of ionic impurities in a liquid crystal panel 1 of a liquid crystal display according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line XX of FIG. 1 and 2 will be described together. As shown in FIG. 1, the liquid crystal panel 1 has a frame portion 15 which is an area which is easily affected by impurities.
And an active area 16 which is a display area. The liquid crystal layer 14, as shown in FIG.
Liquid crystal is sealed between the two substrates, the TFT-side substrate 11 and the CF-side substrate 12, with a gap kept by a seal portion 13. TFT side substrate 11 and CF side substrate 1
2 is made of, for example, a glass substrate. On the TFT-side substrate 11, a TFT including a source bus line 4 and a gate bus line 3 not shown, a pixel electrode not shown, and the like are arranged. On the CF-side substrate 12,
Both include a color filter and a COM electrode (not shown). The gate bus lines 3 and the source bus lines 4 constituting the TFT are arranged in a matrix in a plane orthogonal to the active area 16 as shown in FIG.
The number of the gate bus lines 3 and the number of the source bus lines 4 are m and n, respectively. m and n are natural numbers. Gate bus line 3 and source bus line 4
Are collectively referred to as bus lines.

When the liquid crystal panel 1 thus configured is used, if the ionic impurities 18 enter from the periphery of the liquid crystal panel 1, the frame portion 15 where the ionic impurities 18 have entered has a problem in the gradation characteristics. Expected to occur.
By covering such a frame portion 15 with a light shielding pattern 17, it is possible to prevent the active area 16 from being affected, but this is not sufficient. When the ionic impurities 18 penetrate into the active area 16 and gather at a specific portion, gradation characteristics deteriorate in that portion, resulting in display unevenness and deterioration of display quality. Thus, by diffusing the ionic impurities 18 gathered in the peripheral portion throughout the liquid crystal panel, uniformity in the liquid crystal layer 14 is ensured, local gradation defects are suppressed, and extreme deterioration in display quality is mitigated. . That is, the ionic impurities 18 collected in the peripheral portion
Is moved in the direction of arrow 5 from the peripheral portion to the central portion, whereby the ionic impurities 18 are diffused throughout the liquid crystal panel.

As shown in FIG. 2, a Coulomb force is generated in the liquid crystal layer in order to diffuse the ionic impurities 18 collected in the peripheral portion such as the frame portion 15 throughout the liquid crystal panel.
By the attraction and repulsion of the ionic impurities 18 due to the Coulomb force, the ionic impurities 18 are moved to promote diffusion. For example, the bus line in the liquid crystal panel is used as an electrode,
A few volts by applying a voltage signal to the com electrode on the F-side substrate 12
Is applied. When a voltage signal is applied, a Coulomb force is generated between the ionic impurity 18 and the bus line and the com electrode, and the ionic impurity 18 is moved by the attraction or repulsion of the ionic impurity 18 due to the Coulomb force. Specifically, the following drive system is employed in the liquid crystal display device.

FIG. 3 shows the source bus line 4 [1] of FIG.
It is a schematic diagram which shows the trend of the impurity by the positive-negative change of the voltage of 4 [4]. FIG. 3A is a schematic diagram showing a trend of impurities at a timing 1 when a voltage is first applied to the source bus line 4. FIG. 3B is a schematic diagram illustrating a trend of impurities at a timing 2 when a voltage is applied to the source bus line 4 for the second time. FIG. 3C shows the trend of impurities at the third timing when a voltage is applied to the source bus line 4 for the third time.

At timing 1, the source bus line 4
A positive voltage is applied to [1] to 4 [4]. Since the source bus line 4 to which the positive voltage is applied sucks negative ionic impurities, most of the negative ionic impurities around the seal move to the vicinity of the source bus line 4 [1].

Next, at timing 2, a negative voltage is applied to the source bus line 4 [1] and the source bus line 4 [2]
A positive voltage is applied to .about.4 [4]. The source bus line 4 [1] to which the negative voltage is applied repels the negative ionic impurities collected around at the timing 1. Most of the repelled impurities move in the direction of arrow 19 and are sucked around the source bus lines 4 [2] and 4 [3] to which a positive voltage is applied. Slight impurities are in source bus line 4 [1]
Stay nearby.

Next, at timing 3, a negative voltage is applied to the source bus lines 4 [1] and 4 [2], and a positive voltage is applied to the source bus lines 4 [3] and 4 [4]. Source bus line 4 [2] to which a negative voltage is applied
Repels the negative ionic impurities collected around at the timing 2. Most of the repelled impurities move not in the source bus line 4 [1] to which the negative voltage is applied but in the direction of the arrow 20, and move in the direction of the arrow 20 to which the positive voltage is applied.
It is sucked around [3] and 4 [4]. Slight impurities stay in the vicinity of the source bus line 4 [2] or move in the direction of the source bus line 4 [1] when repelled.

At the time of application of the fourth and subsequent voltages, the source bus lines 4 to be applied are sequentially changed from a positive voltage to a negative voltage to the source bus line 4 located at the center of the liquid crystal panel in the same manner as the timings 1 to 3. It moves from the periphery of the panel to the center. Thus, the negative ionic impurities 18 can be diffused from the periphery of the seal toward the center of the liquid crystal panel 1.

FIG. 3 shows the source bus line 4 [1]
, The voltage is applied from the source bus line 4 located at the center of the liquid crystal panel to the source bus line 4 located at the center of the liquid crystal panel. However, the same applies to the source bus line 4 located at the center of the liquid crystal panel from the source bus line 4 [n]. The same applies to the gate bus lines 3 [1] to 3 [m] as to the source bus lines 4 [1] to 4 [n]. These bus lines move and diffuse ionic impurities from the left, right, upper and lower sides of the liquid crystal panel toward the center, as indicated by arrows 5 in FIG. Further, as described above, the bus line to be applied by changing the voltage from positive to negative is not only moved from the periphery of the panel toward the center, but also moved in all directions around the area where impurities are concentrated. It is also possible to set the moving direction by giving an electric signal to the moving object.

FIG. 4 is a signal waveform diagram showing an example of the drive timing of voltage application to the source bus line 4 in FIG. By synchronizing the transmission of the display signal with the vertical synchronization signal and the horizontal synchronization signal, a frame is displayed. A non-display period occurs in a certain period before and after these synchronization signals. A drive signal for applying a voltage between the source bus line 4 and the com electrode is turned on during the non-display period, that is, at the time of switching the display frame. A driving voltage of several volts is applied during a non-display period on the order of milliseconds (ms).

As the specific drive timing, first,
Assuming that the first non-display period is timing 1, FIG.
A voltage is applied to each source bus line 4 as shown in FIG. Next, with the second non-display period as timing 2, a voltage is applied to each source bus line 4 as shown in FIG. The timing shifts to the next timing for each subsequent non-display period, and the source bus line 4 to be applied with the voltage changed from positive to negative as described above is moved. The same drive timing is employed for the gate bus line 3.

By adopting such a drive timing, an existing signal wiring pattern such as a bus line provided in a liquid crystal display device can be used as an electrode for generating Coulomb force, thereby affecting display. The ionic impurities in the liquid crystal layer can be diffused without affecting the liquid crystal layer.

FIG. 5 is a signal waveform diagram showing a backlight blinking state at the drive timing of FIG. As shown in FIG. 4, during a period in which display driving is OFF (non-display period) between display frame periods, a driving signal for generating Coulomb force is turned on and the backlight is turned off. By applying the drive voltage even during the non-display period,
In some cases, there is a possibility that the display may be affected. Therefore, as shown in FIG. 5, the backlight is turned off only during a period in which the display drive is OFF, that is, during a period in which a drive signal for generating Coulomb force is generated during a switching period of a display frame, the backlight is turned off to turn off the display. Is turned off.
This makes it possible to prevent the application of the driving voltage from affecting the display.

The drive timing shown in FIG. 4 or 5 is achieved by providing a liquid crystal display device with a drive signal for generating Coulomb force and a circuit capable of freely controlling on / off of a backlight. be able to.

FIG. 6 is a signal waveform diagram showing another example of the drive timing of voltage application to source bus line 4 in FIG. A drive signal for generating Coulomb force is turned on when the liquid crystal display device is started, in a power saving mode, at the end, and the like.

In the case where impurities enter from the periphery of the seal during operation of the liquid crystal display device and the entered impurities cause extreme display unevenness, as shown in FIG. 4 and FIG. It is necessary to turn on the drive signal while the display device is operating. However, if the invading impurities are not enough to cause extreme display unevenness or if impurities are mixed in the liquid crystal layer in the manufacturing process of the liquid crystal panel, the driving signal is not necessarily required during the operation of the liquid crystal display device. It is not necessary to remove generated impurities. In the liquid crystal display device, such as when the liquid crystal display device is started, in the power saving mode, and when the liquid crystal display device is shut down, the drive signal is turned on during a non-display period in which the display is off but a current is supplied and a drive signal can be generated. You may make it. Since this period can be secured for several seconds or more, the drive signal is generated by interrupting the non-display period generated in a certain period before and after the two types of synchronization signals as shown in FIGS. Than if you let
The drive signal can be turned on for a long time. Thereby, the ionic impurities can be easily and efficiently moved, and a higher diffusion effect can be expected.

FIG. 7 is a cross-sectional view showing a liquid crystal panel 1 according to the second embodiment provided with a dedicated signal wiring pattern for generating Coulomb force. The liquid crystal panel 1 has a liquid crystal layer 14 divided into a frame portion 15 and an active area 16. The liquid crystal layer 14 is made of TF composed of a glass substrate or the like.
Liquid crystal is sealed between the two substrates, the T-side substrate 11 and the CF-side substrate 12, with a gap kept by a seal portion 13. A TF including a source bus line 4 and a gate bus line 3 (not shown)
T, a pixel electrode 22, and the like are arranged. On source bus line 4, an electrode 21 for generating Coulomb force is arranged via an insulating layer 23. Further, electrodes are arranged on a gate bus line 3 (not shown), similarly to on the source bus line 4. CF side substrate 1
2 includes a color filter and a COM (not shown).
Electrodes and the like are arranged. The gate bus lines 3 and the source bus lines 4 forming the TFT are arranged in a matrix in the active area 16 in a manner orthogonal to each other. That is, the configuration is the same as that of the first embodiment except for the configuration in which the electrode 21 is provided.

An exclusive electrode 21 provided in the liquid crystal panel
And a voltage of several volts by applying a voltage signal to the com electrode. The application of the voltage signal generates a Coulomb force between the electrode 21 and the com electrode. By the attraction or repulsion of the ionic impurities 18 due to the Coulomb force, the ionic impurities 18 collected in the peripheral portion such as the frame portion 15 are diffused throughout the liquid crystal panel.
That is, the liquid crystal display device according to the second embodiment has a configuration in which a dedicated electrode 21 is provided to generate Coulomb force without using the bus line used in the first embodiment. Therefore, a voltage is applied to the electrode 21 corresponding to the source bus line 4 in the same manner as the source bus line 4 in FIG. A voltage is similarly applied to the electrodes on the gate bus line 3. The drive timing for applying the voltage to the electrode 21 is the same as in FIG. 4, FIG. 5, or FIG. As a result, in the liquid crystal display device according to the second embodiment, similarly to the liquid crystal display device according to the first embodiment, the ionic impurities 18 are diffused from the peripheral portion of the seal toward the center of the liquid crystal panel 1 without affecting the display. be able to. Due to this diffusion, uniformity in the liquid crystal layer 14 is ensured, and local gradation defects can be suppressed to prevent deterioration of display quality.

In the liquid crystal display device according to the second embodiment, since the electrode 21 for generating Coulomb force is a wiring independent of the bus line, the layout of the electrode 21 is less restricted. Therefore, an electrode layer including the electrode 21 can be provided in contact with the liquid crystal layer 14, and a pattern such as the electrode 21 [1], the electrodes 21 [2] and 21 [3] can be provided. Thus, the electrodes 21 [1], 21
When [2] and 21 [3] are in close contact with the liquid crystal layer 14, the movement of the ionic impurities 18 becomes easier, and an efficient diffusion effect can be obtained. That is, when the electrode 21 is used, the electric field is weakened by sandwiching the insulating layer 23 between the bus line 4 and the liquid crystal layer 14 as in the case where the bus line 4 is used as an electrode for generating Coulomb force. Because there is nothing.

[0040]

As described above, according to the present invention, it is possible to maintain the uniformity of the display surface by diffusing the ionic impurities throughout the liquid crystal panel by applying an electric signal to move the ionic impurities. Thus, it is possible to provide a liquid crystal display device capable of avoiding occurrence of portions having different characteristics partially and having a significant influence on display quality. In particular, since the direction of movement of the ionic impurities can be arbitrarily controlled by regularly applying the electric signal to each electric signal line, the ionic impurities can be easily diffused throughout the liquid crystal panel, and the This makes it possible to suppress poor gradation failure and to alleviate extreme deterioration in display quality.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of movement and diffusion of ionic impurities in a liquid crystal panel 1 according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view taken along line XX of FIG.

3 is a schematic diagram showing a trend of impurities due to a positive or negative change of a voltage of a source bus line 4 of FIG. 2;

FIG. 4 is a signal waveform diagram showing an example of drive timing for applying a voltage to a source bus line 4 in FIG. 3;

FIG. 5 is a signal waveform diagram showing a backlight blinking state at the drive timing of FIG. 4;

FIG. 6 is a signal waveform diagram showing another example of drive timing for applying a voltage to the source bus line 4 of FIG.

FIG. 7 is a cross-sectional view showing a liquid crystal panel of Embodiment 2 provided with a dedicated signal wiring pattern for generating Coulomb force.

FIG. 8 is a cross-sectional view illustrating a configuration example of a conventional liquid crystal panel.

9 is a cross-sectional view showing a configuration example in which an impurity adsorption pattern is provided in the conventional liquid crystal panel of FIG.

FIG. 10 is a cross-sectional view schematically showing how impurities move in a conventional liquid crystal panel provided with an impurity adsorption electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 3 Gate bus line 4 Source bus line 5 Impurity moving direction 15 Frame 16 Active area 17 Light-shielding pattern 18 Ionic impurities 19, 20 Impurity moving direction 21 Electrode 22 Pixel electrode 23 Insulating layer

Claims (7)

[Claims] 1. A liquid crystal display device comprising an electric signal line for supplying an electric signal for moving and diffusing ionic impurities mixed in a liquid crystal layer. 2. The method according to claim 1, wherein a plurality of the electric signal lines are provided on the display surface, and the electric signal lines regularly generate an electric signal for generating a Coulomb force for attracting or repelling ionic impurities. The liquid crystal display device according to claim 1. 3. The electric signal line according to claim 1, wherein the electric signal line is a signal line provided to be used for display.
The liquid crystal display device according to the above. 4. The liquid crystal display device according to claim 1, wherein the electric signal line is provided separately from a signal line provided for use in display. 5. The liquid crystal display device according to claim 1, wherein the electric signal is provided in a non-display period between each frame display period in a display period. 6. The liquid crystal display device according to claim 1, wherein the electric signal is given during a non-display period when a backlight is not turned on. 7. The liquid crystal display device according to claim 5, wherein a backlight is turned off during the non-display period.