JPH06149192A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To stabilize the display of a frame part by impressing the signals of waveforms different from each other to one side and the other side frame information electrodes respectively. CONSTITUTION:In a liquid crystal display device provided with a display part arranging a ferroelectric liquid crystal between an electrode substrate having a scanning electrodes group and the electrode substrate having an information electrodes group and forming so as to display by a first stable condition and a second stable condition, and a frame part arranging the frame scanning electrode and the frame information electrode and forming so as to perform a fixed frame display by the liquid crystal and a drive signal impression means impressing a drive signal to respective electrodes and performing the displays in the display part and the frame part, the waveforms of the signals impressed to the frame information electrode by the drive signal impression means differ from between the frame information electrode arranged to the outside of one side of the display part and the frame information electrode arranged to the outside of the other side.

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 having a frame portion using a ferroelectric liquid crystal.

[0002]

2. Description of the Related Art An electro-optical medium having a memory property is subjected to desired switching by applying an electric field above a threshold value, and then the state after switching is maintained even if no electric field or an electric field below the threshold value is applied. To be done. A medium having such characteristics has the effect of its memory property.
Once the desired switching is performed by the write signal, the information is stored, so that it can be applied to a large-capacity display element or the like.

A typical example of the electro-optical medium having the memory property is a ferroelectric liquid crystal. By sandwiching a ferroelectric liquid crystal (FLC) between substrates that have been subjected to an appropriate alignment treatment and forming a cell in which the liquid crystal is thin enough to eliminate the helical structure, two stable states having a memory property are exhibited.

In such a liquid crystal cell, at least one polarizer is used, and it is possible to distinguish the above two stable states into a dark state and a bright state by utilizing the birefringence of the liquid crystal.
The switching between the two states is controlled by an electric signal applied via the electrode formed by performing desired patterning on the substrate.

In such a liquid crystal cell, generally, a stripe-shaped scanning electrode group is formed on one substrate and a stripe-shaped information electrode group is formed on the other substrate, and applied to these electrode groups. It is used as a display element by writing a bright state and a dark state in a pixel formed at an intersection of each electrode group by a combination of a scanning signal and an information signal.

By the way, when an electro-optic medium having a memory property such as FLC is used as a display element, there are the following problems.

That is, the display element has a functional, safety,
In addition, the device is housed in a chassis or a cosmetic case in order to protect the electric system and keep the appearance, but the display surface may be hidden when viewed from an oblique direction due to the thickness of the chassis or the cosmetic case. To avoid such cases,
A non-display portion is provided around the display portion so that the effective display area is not hidden unless viewed from an angle other than a certain range.

However, in such a case, in the case of a medium having a memory property such as FLC, in the above non-display portion, the FLC is in an arbitrary state until an electric signal equal to or more than the threshold value is applied, so that the non-display portion is not displayed. The parts are uncontrolled, the display is non-uniform, and it is unsightly for practical use, and the aesthetics are spoiled. Therefore, it is necessary to make the non-display portion uniform by a certain electric signal. However, the memory property here is not permanent as long as it satisfies the image quality and the display function as a display element. Therefore, it is necessary to apply the drive signal periodically.

Therefore, a uniform frame portion is provided by providing a frame portion drive electrode around the display portion and applying an electric signal to the electrode in the same manner as the display portion or substantially the same as the display portion to drive the liquid crystal in the frame portion. It has been conventionally proposed to realize the above (for example, Japanese Patent Publication No. 2-30022 and Japanese Patent Publication No. 4-232).
No. 75, etc.).

[0010]

However, according to such a conventional technique, the cell thickness is likely to be thick in the vicinity of the sealing material, the compounded state is likely to be rough near the liquid crystal injection port, and the waveform applying circuit is close. Since the temperature easily fluctuates, the threshold value of the frame portion is likely to vary greatly, and stable display cannot be performed on the frame portion, so that the display device may not function sufficiently.

An object of the present invention is to stabilize the display of the frame portion in a liquid crystal display device in view of the above problems of the prior art.

[0012]

In order to achieve this object, according to the present invention, a ferroelectric liquid crystal is arranged between an electrode substrate having a scanning electrode group and an electrode substrate having an information electrode group.
Display unit formed so as to display in the stable state and the second stable state, and a frame scan electrode and a frame information electrode are arranged outside the scan electrode group and the information electrode group to display a constant frame by the liquid crystal. In a liquid crystal display device including a frame portion formed so as to perform a drive signal application means for applying a drive signal to each of the electrodes to perform display on the display portion and the frame portion, the drive signal application means includes a frame information electrode. The waveform of the signal applied to the frame information electrodes arranged on one outside of the display unit is different from that of the frame information electrodes arranged on the other side of the display unit.

The waveforms of the signals applied to the one and the other frame information electrodes may be different only in voltage value.

The direction of the frame scanning electrode is from -45 ° to + with respect to the direction in which the distribution of the switching threshold value between the first and second stable states is severe, or the liquid crystal injection direction.
It is desirable to set the direction between 45 °.

The signal applied to the frame scanning electrodes by the drive signal applying means has, for example, a waveform having a reset effect for displaying the first stable state or the second stable state regardless of the display state before the application. Yes, the frame display is preferably in a bright state due to any stable state.

[0016]

In this structure, the switching threshold of the liquid crystal in the frame portion usually differs depending on the location, and has a certain distribution such that it changes along the injection direction of the liquid crystal, so that the threshold characteristic that allows stable frame display can be achieved. Range (margin) is different between the frame part on the frame information electrode arranged on one outside of the display part and the frame part on the frame information electrode arranged on the other side of the display part. Therefore, by making the waveform of the signal applied to the frame information electrode different between the one frame information electrode and the other frame information electrode, and by making it appropriate according to the margin in each frame portion, Stable frame display is performed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. Here, the present invention has a liquid crystal panel in which 1024 scanning electrodes, 2560 information electrodes, 23 frame scanning electrodes at both ends of the scanning electrodes, and 46 frame information electrodes at both ends of the information electrodes are arranged. An example in which the present invention is applied to a liquid crystal display device will be described.

FIG. 1 is a block diagram showing a circuit configuration of a liquid crystal display device according to an embodiment of the present invention. In the figure,
101 is a panel unit, 102 is a display unit, 103a and 103
b, 103c, 103d and 103e are frame portions, 105 is a wiring pattern that connects both ends of the frame scanning electrode 203 (see FIG. 2), 106 is a wiring pattern that connects both ends of the frame information electrode 206 (see FIG. 2), and 107 is a scan Signal applying circuit, 108
Is an information signal application circuit, 109 is a scanning signal control circuit, 11
0 is an information signal control circuit, 111 is a drive control circuit, 112
Is a graphic controller.

The data sent from the graphic controller 112 enters the scanning signal control circuit 109 and the information signal control circuit 110 through the drive control circuit 111, and is converted into address data and display data, respectively. At this time, the frame data is generated by the drive control circuit 111, but may be generated by the graphic controller 112 in advance. Then, the scan signal applying circuit 107 generates a scan signal in accordance with the address data, and the scan electrodes 202 (see FIG. 2) of the panel unit 101 and the frame scan electrodes 2 are generated.
03 (see FIG. 2). At this time, the scanning signal applying circuit 107 operates similarly to the case where there are 1024 + 2 scanning electrodes. Further, the information signal applying circuit 108 generates an information signal according to the display data, and the information electrode 205 (see FIG. 2) and the frame information electrode 206 (see FIG. 2) of the panel section 101.
Apply to. At this time, the information signal application circuit 108 operates similarly to the case where there are 2560 + 2 information electrodes.

FIG. 2 shows an electrode pattern structure of the panel section 101. In the figure, 1024 scanning electrodes 202 are provided on the scanning-side substrate 201 and two frame scanning electrodes 203 are provided at both ends thereof.
There are three electrodes, and a total of 1,070 electrodes are arranged in one direction with the same shape. The information side substrate 204 has 2560 information electrodes 205 and 46 frame information electrodes 206 at both ends thereof, and a total of 2652 electrodes have the same shape. When the scanning side substrate 201 and the information side substrate 204 are superposed on each other. The electrodes on the substrates are arranged side by side in a direction in which the electrodes have a vertical or nearly vertical relationship. A matrix electrode is formed by superposing the two substrates.

Reference numeral 310 denotes a sealing material arranged to seal the liquid crystal in the panel portion 101, and the liquid crystal injection port 209.
Is on the side of the frame 103d on the right hand side in the drawing, and the liquid crystal injection direction is the direction of wetting the arrow 210, that is, the frame 10
This is the direction from 3d to 103e.

With such an injection direction, the alignment state of the liquid crystal varies depending on the location due to conditions such as temperature and internal pressure at the time of injection, and as shown in FIG. It has a threshold distribution in the direction between 45 ° and + 45 °. As a result, the frame portion 103a has a high threshold,
The frame portion 103b has a wide distribution from low to high threshold portions, and the frame portion 103c has a low threshold value.
Has a high threshold, and the frame 103e has a low threshold.

FIG. 4 is a partial sectional view of the panel portion 101. In the figure, 301 is an analyzer and 309 is a polarizer, which are located in crossed Nicols. 302 and 308 are glass substrates, 303 and 307 are insulating films, 304 and 306 are alignment films, 305 is a ferroelectric liquid crystal, 310 is a seal member, and 311 is a pixel which is a display unit.

FIG. 5 shows the waveform of the drive signal in the device of FIG. In the figure, a waveform A is a waveform of a scanning selection signal of the display unit, and is composed of a pulse for resetting to a dark state, a selection pulse, and an auxiliary pulse. The waveform B is the waveform of the scanning non-selection signal of the display unit (scanning electrode 202), and the voltage level is zero. A waveform C is a waveform of the scanning selection signal of the frame portion (frame scanning electrode 203), and is composed of an auxiliary pulse and a pulse for resetting to a bright state.

The waveform D is the waveform of the scanning non-selection signal of the frame portion, and the voltage level is zero. The waveform E is the waveform of the display bright information signal during the scanning of the display, the waveform F is the waveform of the display dark information signal during the scanning of the display, and the waveform G is the frame 10 during the scanning of the display.
A waveform of the frame information signal 1 applied to the information electrode 206 on the 3d side, a waveform H is a waveform of the frame information signal 2 applied to the information electrode 206 on the frame 103e side during scanning of the display unit, both of which are selection pulses. It consists of the auxiliary pulse before and after that,
The average potential in one unit is zero.

I, J, K and L are a bright information signal, a dark information signal, a frame information signal 1 and a frame information signal 2 respectively at the time of frame scanning, all of which have a voltage level of zero.

Note that the voltage of each information signal is set to zero when scanning the frame portion because the number of steps for generating the display data of the upper and lower frame portions is saved, the power consumption during the frame scanning is suppressed, and This is to avoid continuous driving and improve durability.

In addition, the reason why the frame portion is in the bright state is that the visual response to a pulse below the threshold value is gentler than that in the dark state, and flicker, flicker, crosstalk, light leakage due to alignment defects, etc. are difficult to understand. Is.

FIG. 6 shows a composite waveform for displaying the bright state on the display section and the frame section. In the figure, M is the display unit 10.
2 and the waveform of the combined signal applied to the frame 103e, O is the waveform of the combined signal applied to the frames 103a, 103b and 103c, and P is the waveform of the combined signal applied to the frame 103d.

FIG. 7 is a graph showing the pulse width-transmittance characteristics of the waveforms M, O and P at 30 ° C. The solid line 71 shows the waveform M, the broken line 73 shows the waveform O, and the solid line 75 shows the waveform P, and the respective bright display ranges are m, o, and p. However, when measuring, the pulse width (ΔT) gradually increases from the dark state.
The pulse width was gradually narrowed from the middle. Further, the voltages V _{1 to} V ₅ shown in FIG. 5 are V ₁ = 10v,
_{V 2 = -10v, V 3 =} 5.5v, V 4 = 5v, V 5 =
The transmittance was set to -5 v and the transmittance was set to 100% in the bright state.

As is apparent from FIG. 7, in the waveforms M, O, and P, when the pulse width is widened and narrowed, a hysteresis phenomenon in which the transmittance is different even if the pulse width is the same appears. At this time, comparing the ranges in which each waveform can stably display the bright state, the waveform O is more stable than the waveform M over a wide range. Therefore, by applying the waveform O to the frame portion 103b having a strong threshold distribution to bring it into a bright state, a good display can be obtained even when the threshold distribution is more intense.

Further, the waveform P has a wider stable range in the longer pulse width direction than the waveform M. Therefore, by applying the waveform P to the frame portion 103d having a high threshold value (which requires a long pulse width) to bring it into a bright state, a good display can be obtained even when the threshold value becomes higher.

As described above, by applying a waveform corresponding to the threshold distribution of each side of the frame portion, the display device as a whole can display more stably than before. FIG. 8 shows a conventional drive waveform. However, when the signal of the display unit and the signal of the frame unit are the same, the margin for the bright display of the frame unit is not widened.

FIG. 10 is a timing chart showing the timing of signal transmission / reception between the graphic controller 112 and the drive control circuit 111 of the apparatus shown in FIG. Figure 1
Further, in FIG. 10, SYNC is a synchronizing signal, and its “L” level means a data transfer request from the drive control circuit 111 to the graphic controller 112. As the data, 4-bit parallel data PD0 to PD3 are transferred every one clock of the transfer clock CK. Here, the address data AD and the display data DD are transferred using the same data bus. AH / DL is a signal for identifying the type of data being transferred. The “H” level means that the address data AD is being transferred, and the “L” level means that the display data DD is being transferred. .

The ferroelectric liquid crystal used in this example contains a pyrimidine component and has the characteristics shown in Table 1 below.

[0036]

[Table 1] FIG. 9 shows driving waveforms according to another embodiment of the present invention. When this waveform is used, it has substantially the same margin as the drive waveform shown in FIG. Further, the voltage V ₆ of the waveform of the frame information signal 1
By finely adjusting the values of V and V ₇ , it is possible to adjust the range in which good bright display is possible to some extent.

However, while the waveform of the frame information 1 shown in FIG. 5 is composed of V ₄ and 2V ₅ and the ternary voltage of zero level, the frame information waveform 1 shown in FIG. 9 is V ₄ and V _6. ，
The cost is high because a frame information signal applying circuit for four-value output is required in addition to the three-value display section information signal applying circuit which is composed of V ₇ and a zero-level four-valued voltage.

FIG. 11 shows driving waveforms according to still another embodiment of the present invention. The waveforms A ′ to L ′ are waveforms used in the same portions as the waveforms A to L in FIG. 5, respectively.
It has the same structure, but V ₈ > V ₄ > V ₁₀ and | V ₉ |>
| V ₅ |> | V ₁₁ |.

FIG. 12 is a waveform diagram showing a composite waveform for displaying the bright state on the display section and the frame section. In the figure,
The waveform M ′ is the waveform of the composite signal applied to the display unit 102, and O ′.
Is the waveform of the composite signal applied to the frame portions 103a, 103b, 103c, P'is the waveform of the composite signal applied to the frame portion 103d,
Q'is the waveform of the combined signal applied to the frame 103e.

FIG. 13 shows three waveforms M ', O', P ', and Q'.
It is a graph which shows the pulse width-transmittance characteristic in 0 degreeC. The dotted line 131 shows the waveform M ', the thick line 133 shows the waveform O', the broken line 135 shows the waveform P ', and the solid line 137 shows the waveform Q', and the respective bright display ranges are m ', o', p ', and q'. Become. When measuring, the pulse width (Δ
T) was gradually widened, and the pulse width was gradually narrowed from the middle. The voltages shown in FIG. 11 are V ₁ = 10v, V
_{2 = -10v, V 3 = 5.5v} , V 4 = 5v, V 5 = -
_{5v, V 8 = 6.5v, V} 9 = -6.5v, V 10 = 3.
5 v and V ₁₁ = −3.5 v were set, and the transmittance was set to 100% in the bright state.

As is apparent from FIG. 13, the waveforms M ',
For each of O ', P', and Q ', there is a hysteresis phenomenon in which the transmittance is different even when the pulse width is widened or narrowed. At this time, comparing the range in which each waveform can stably display the bright state, the waveform O'is more stable than the waveform M'in a wider range. Therefore, by applying the waveform O ′ to the frame portion 103b having a strong threshold distribution to bring it into a bright state, a good display can be obtained even when the threshold distribution is more intense.

Further, the waveform P'has a wider stable range in the direction of the longer pulse width than the waveform M '. Therefore, by applying the waveform P ′ to the frame portion 103d having a high threshold value (which requires a long pulse width) to bring it into a bright state, a good display can be obtained even when the threshold value becomes higher.

Further, the waveform Q'has a wider stable range in the direction of the shorter pulse width than the waveform M '. Therefore, by applying the waveform Q'to the frame portion 103e having a low threshold value (needing a short pulse width) to bring it into a bright state, a good display can be obtained even when the threshold value becomes lower.

As described above, by applying a waveform corresponding to the threshold distribution of each side of the frame portion, stable display can be performed as compared with the conventional display device.

[0045]

As described above, according to the present invention, it is possible to apply an appropriate signal to each frame portion in accordance with the range of the threshold characteristic that allows stable frame display in the frame portion on each side. Therefore, it is possible to stabilize the display of the frame portion and maintain good display of the frame portion.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an electrode pattern configuration of a panel section in the device of FIG.

FIG. 3 is an explanatory diagram for explaining a threshold distribution of a liquid crystal panel in the device of FIG.

FIG. 4 is a partial cross-sectional view of a panel portion in the device of FIG.

5 is a waveform diagram showing a waveform of a drive signal in the device of FIG.

FIG. 6 is a waveform diagram of a composite waveform based on the waveforms of FIG.

7 is a graph showing pulse width-transmittance characteristics when the waveform of FIG. 6 is used.

FIG. 8 is a waveform diagram showing a conventional waveform.

FIG. 9 is a waveform diagram of a drive signal according to another embodiment of the present invention.

10 is a timing chart showing the timing of signal exchange between the graphic controller and the drive control circuit in the device shown in FIG.

FIG. 11 is a waveform diagram of a drive signal according to still another embodiment of the present invention.

FIG. 12 is a waveform diagram of a composite waveform based on the waveforms in FIG.

13 is a graph showing pulse width-transmittance characteristics when the waveform of FIG. 12 is used.

[Explanation of symbols]

101: panel part, 102: display part, 103a, 103
b, 103c, 103d, 103e: frame portion, 105: wiring pattern, 106: wiring pattern, 107: scanning signal applying circuit, 108: information signal applying circuit, 109: scanning signal control circuit, 110: information signal control circuit, 111 : Drive control circuit, 112: graphic controller, 30
1: analyzer, 302, 308: glass substrate, 30
3, 307: insulating film, 304, 306: alignment film, 30
5: Ferroelectric liquid crystal, 309: Polarizer, 310: Seal member, 311: Pixel to be a display unit.

Claims (6)

[Claims] 1. A ferroelectric liquid crystal is arranged between an electrode substrate having a scanning electrode group and an electrode substrate having an information electrode group to form a display in a first stable state and a second stable state. A display section, a frame section formed by arranging a frame scan electrode and a frame information electrode outside the scan electrode group and the information electrode group to perform a constant frame display by the liquid crystal, and a drive signal to each of these electrodes. In a liquid crystal display device provided with a drive signal applying means for applying a display and a display in the frame part, the waveform of the signal applied to the frame information electrode by the drive signal applying means is arranged outside one of the display parts. A liquid crystal display device characterized in that a frame information electrode and a frame information electrode arranged outside the other are different. 2. The liquid crystal display device according to claim 1, wherein waveforms of signals applied to the one and the other frame information electrodes are different from each other only in voltage value. 3. The liquid crystal display device according to claim 1, wherein the direction of the frame scanning electrode is set in a direction in which the distribution of the switching threshold between the first and second stable states is intense. 4. From -45 ° to + with respect to the liquid crystal injection direction.
3. The liquid crystal display device according to claim 1, wherein the direction of the frame scanning electrode is set to a direction between 45 [deg.]. 5. The signal applied by the drive signal applying means to the frame scanning electrode has a waveform having a reset effect for displaying the first stable state or the second stable state regardless of the display state before the application. 5. The liquid crystal display device according to claim 3 or 4. 6. The liquid crystal display device according to claim 1, wherein the constant frame display by the liquid crystal is a bright state according to the first or second stable state.