JPH08304772A - Driving method for ferroelectric liquid crystal display panel - Google Patents

Abstract

PURPOSE: To perform a temperature compensation for a voltage-response speed characteristic of a ferroelectric liquid crystal material by impressing a temp. compensating voltage on a scanning electrode. CONSTITUTION: This driving method for a ferroelectric liquid crystal display panel is provided constituting each picture element at each crossing part of scanning electrode L and signal electrode S with a frroelectric smectic liquid crystal 6 with two stable states interposed, impressing a signal voltage on the signal electrode S based on a picture information data and impressing a scanning voltage consisting of selective or non-selective voltage wave form on the scanning electrode L in synchronism with the signal voltage. Before or after the time of impressing the selective voltage on the scanning electrode, namely, with a time interval shifted from the impressing time, a compensating voltage with an effectively opposite polarity to the selective voltage is impressed on the scanning electrode L, and the responsiveness of the liquid crystal fluctuating with temperature is compensated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a ferroelectric liquid crystal display panel.

[0002]

2. Description of the Related Art Ferroelectric liquid crystals such as chiral smectic C-phase liquid crystals have excellent characteristics such as memory property, high-speed response and wide viewing angle, and are suitable for liquid crystal display devices with high definition and large display capacity. The application is being actively studied. However,
One of the biggest problems in putting a large-screen display into practical use is temperature dependency of driving characteristics. That is, the liquid crystal operating temperature of each part in the display panel is
The distribution is generated under the influence of the ambient temperature, and the temperature difference becomes more remarkable depending on the display size.

As a result, the response speed changes in response to material properties such as viscosity having large temperature dependence and spontaneous polarization, and it becomes impossible to control the display state to the intended state if the driving conditions are fixed, and the display quality is remarkably increased. It will be lowered.

To solve this problem, a method of adjusting the pulse width of the applied drive waveform or the pulse amplitude value to compensate for the temperature has been studied. For example, as described in Japanese Patent Laid-Open No. 61-245140, there is known a method of adjusting the pulse width with respect to temperature change. In addition, JP-A-6
As described in JP-A 1-249024, there is known a method of adjusting the pulse amplitude value to perform temperature compensation.

By the way, there is an FLC material which exhibits a minimum value in the voltage-response speed (τ-V) characteristic under a practical driving voltage. As a high-speed / wide-margin driving method utilizing this τ-Vmin characteristic, a method described in Japanese Patent Application Laid-Open No. 1-24234 is known. This drive mode is generally
When the response speed increases due to the temperature rise, the pulse width is shortened or the drive voltage is increased to compensate for the temperature.

The operation opposite to the conventional drive mode having a τ-V curve that is decreasing to the right is performed in that the drive voltage is reduced and compensated for the temperature rise. The reason for this is that, as shown in FIG. 11, the τ-Vmin curve shifts to the lower right, that is, to the high voltage side as the temperature rises.

For example, even if the optimum driving conditions are set near room temperature, a stable driving margin cannot be obtained by temperature compensation of only the pulse width, and uniform control within the panel becomes difficult. Particularly, as the temperature rises, the driving margin decreases remarkably, and stable compensation is very difficult without compensation by increasing the pulse amplitude value.

As a difference from the conventional drive mode, as described in Japanese Patent Laid-Open No. 1-24234, a method of performing compensation by increasing or decreasing only the amplitude value of the first slot portion in the strobe waveform within the selection period. Is proposed.

[0009]

However, it has been found that any compensation method based on the amplitude change has a serious problem in practical use. First, it requires multiple different voltage values, which complicates the drive circuit, leading to higher costs. Also, when the temperature rises, the voltage is increased and the pulse width is reduced (higher drive frequency), resulting in consumption. It was found that the electric power increased significantly and the heat generated from the panel became a problem. Inherently, high-frequency and high-voltage driving imposes a heavy burden on the circuit and is not preferable in terms of durability.

In view of the above, according to the present invention, a temperature compensation voltage is applied to the scanning electrodes to compensate the voltage-response speed characteristics of the ferroelectric liquid crystal material in the FLC panel by temperature compensation. Greatly reduces high voltage and high frequency,
Moreover, it is an object of the present invention to provide a driving method of a ferroelectric liquid crystal display panel which can be realized at low cost by a relatively simple method.

[0011]

According to the present invention, a ferroelectric smectic liquid crystal having two stable states is interposed at each intersection of a scanning electrode and a signal electrode arranged in directions intersecting with each other. Driving a ferroelectric liquid crystal display panel that constitutes a pixel, applies a signal voltage based on image information data to a signal electrode, and applies a scanning voltage consisting of a selection voltage waveform or a non-selection voltage waveform to the scanning electrode in synchronization with this. In the method, a temperature compensation voltage having a waveform that is effectively opposite in polarity to the selection voltage is applied to the scan electrode before or after the selection voltage is applied to the scan electrode, with a certain time interval from the application time. A method of driving a ferroelectric liquid crystal display panel, characterized by compensating for the response of a liquid crystal that is applied and fluctuates depending on temperature.

In the above structure, the time lag of the temperature compensation voltage with respect to the application timing of the selection voltage is preferably set shorter as the temperature of the liquid crystal is higher and longer as the temperature of the liquid crystal is lower. The amplitude value may be equal to or smaller than the threshold value for changing the pixel state, or may be the pulse width and the amplitude value equal to or larger than the threshold value for rewriting the pixel state to one stable state.

Specifically, according to the present invention, a voltage waveform having a polarity opposite to that of the selection voltage waveform is adjusted according to a temperature change.
This is a driving method of a ferroelectric liquid crystal display panel in which a slot time (t _s ) times (real number of 0 or more) times is applied at intervals.

That is, a pulse waveform having an opposite polarity to the waveform applied during the selection period is applied before and after the selection period for a time adjusted manually or by a temperature control circuit having a temperature detector.

In this case, the value of the temperature compensation voltage application timing m is preferably close to 0 when the operating temperature is high and is large when the operating temperature is low.

Further, according to the present invention, each pixel is constructed by interposing a ferroelectric smectic liquid crystal having two stable states at each intersection of a scanning electrode and a signal electrode arranged in a direction intersecting with each other. A method of driving a ferroelectric liquid crystal display panel, wherein a signal voltage based on image information data is applied to a signal electrode, and a scanning voltage having a selection voltage waveform or a non-selection voltage waveform is applied to the scanning electrode in synchronization with the signal voltage. , A first period in which the selection period is zero voltage and a second period in which a predetermined voltage is applied to the scan electrode.
A voltage having a waveform consisting of a period is applied, and at least two voltages, that is, a first voltage and a second voltage having a polarity opposite to that of the first voltage are applied to the signal electrode, and the switching timing of the first voltage and the second voltage is scanned. The method of driving a ferroelectric liquid crystal display panel is characterized in that the voltage switching timing is changed by an external signal in synchronization with the end of the first period of the voltage.

In the above structure, when the voltage is applied,
It is preferable to adjust the switching timing of the first voltage and the second voltage according to the temperature change of the liquid crystal, and in this case, the time from the start of the selection period to the switching timing of the first voltage and the second voltage is It is more preferable that the higher the temperature of the liquid crystal is, the longer the temperature is, and the lower the temperature is, the shorter the temperature is adjusted.

Specifically, the present invention is a driving method for sequentially reading an applied voltage signal from a memory circuit in which waveform pattern data forming a scanning voltage waveform and a signal voltage waveform is stored and held in n bits. However, the number i of bits smaller than n forming the first voltage is zero, the (n−i) bit forming the second voltage is voltage | V1 |, and the signal voltage waveform is the first The i bit forming the voltage is the voltage | V0 | and forms the second voltage (n / 2)
The bit is a voltage | V0 | having a polarity opposite to the first voltage, and the (n / 2-i) bit forming the third voltage is a voltage | V0 | having the same polarity as the first voltage, and the value of i is the temperature. This is a method of driving a ferroelectric liquid crystal display panel, which is adjusted by a control signal or the like.

In this case, it is preferable that the value of i that determines the applied waveform pattern is close to n at high temperature and close to 0 at low temperature. Further, it may be used in combination with a conventional compensation method using a pulse width or a driving voltage.

Furthermore, the present invention is a method for driving a ferroelectric liquid crystal display panel, characterized in that the ferroelectric liquid crystal display panel is driven by simultaneously using the above two driving methods.

[0021]

According to the present invention, by applying the temperature compensating voltage or changing the ratio of the voltage waveform applied to the scanning electrode and the signal electrode, the driving voltage is increased and the driving frequency is increased in the high temperature region. It is possible to suppress the increase in power consumption, improve the problem of increased power consumption and heat generation, and improve the display quality and durability.

The driving method of the present invention utilizes the fact that the response speed changes by controlling the position of the molecules of the ferroelectric liquid crystal before and after the selection period and within the selection period. Regarding the ferroelectric liquid crystal having a specific applied voltage Vmin that minimizes the response speed in the relationship between the applied voltage and the response speed (τ-Vmin characteristic), the dielectric anisotropy has a great influence on the drive characteristics. Are known.

In the conventional temperature compensation driving method, since the spontaneous polarization is most dominant in the switching mechanism of the ferroelectric liquid crystal, two parameters of the pulse width and the pulse amplitude value are adjusted to switch the liquid crystal material. The basic method was to follow the change in the threshold value. Therefore, there has been no effective method of suppressing the driving conditions from becoming a high voltage and a high frequency particularly in a high temperature region.

In the first method for driving a ferroelectric liquid crystal display panel of the present invention, an electric field of opposite polarity can be applied in advance before switching control in the selection period to control the local effective voltage value. In the case of a ferroelectric liquid crystal having a negative dielectric anisotropy, the apparent tilt angle becomes large when the voltage effective value is large, and the response speed can be suppressed.

Further, when the temperature compensation pulse voltage is applied at a timing close to the selection period, the position of the molecular director moves in the direction opposite to the switching direction within the selection period in response to this pulse voltage, and the effective voltage value is increased. In addition, the response speed can be affected.

That is, in the high temperature operation region, the local voltage effective value is increased and the position of the liquid crystal molecule before the selection voltage is applied by the temperature compensation pulse voltage by spontaneous polarization is moved in the direction opposite to the switching direction. Keep it. as a result,
The temperature compensation effect can be obtained only by adjusting the application timing of the temperature compensation pulse voltage without adjusting the pulse width or the amplitude value. Other than this, the reason why the effect of the compensation voltage appears is considered to be related to the ionic behavior in the liquid crystal layer, but the details are not known.

Further, in the second method for driving the ferroelectric liquid crystal display panel of the present invention, the waveform pattern in the selection period is changed. A major feature of the τ-Vmin driving method is that a large driving area can be obtained even with monopulse driving. When the pixel state is desired to be rewritten, the first voltage and the second voltage have the same polarity, and when the pixel state is desired to be retained, the first voltage and the second voltage have opposite polarities, so that the response speeds of both drive voltages change significantly. I know.

On the other hand, if the drive voltage is not changed with respect to the temperature change of the liquid crystal, the Vmin of the material characteristics fluctuates, so that the drive region tends to narrow in the high temperature part and wide in the low temperature part. In the present invention, the proportion of the zero voltage portion within the selection period is adjusted according to the temperature change of the liquid crystal, and is adjusted to be large in the high temperature region and small in the low temperature region to ensure a necessary and sufficient drive margin. In particular, since the rewriting pulse area in the selection period can be increased in the low temperature portion, the reduction in response speed can be compensated.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to Embodiments 1 to 4 shown in the drawings. The present invention is not limited to this.

[Embodiment 1] FIG. 1 is a sectional view showing a schematic structure of a ferroelectric liquid crystal display panel (hereinafter referred to as "FLC panel") used in a driving method of the present invention.

In this FLC panel 1, two glass substrates 2a and 2b are arranged so as to face each other, and indium tin oxide (hereinafter referred to as "IT") is formed on the surface of one glass substrate 2a.
A plurality of transparent signal electrodes S made of "O" are arranged in parallel with each other, and a transparent insulating film 3a made of SiO ₂ is formed thereon.

On the surface of the other glass substrate 2b facing the signal electrode S, a transparent scanning electrode L made of ITO is formed.
Are arranged in parallel to each other in a direction orthogonal to the signal electrode S, and a transparent insulating film 3b made of SiO ₂ is covered thereover. On each insulating film 3a, 3b,
Alignment film 4 uniaxially oriented by rubbing
a and 4b are formed. A polyimide film or an organic polymer film of polyvinyl alcohol is used as the alignment films 4a and 4b.

The two glass substrates 2a and 2b are bonded together with a sealant 5 leaving an injection port in a part, and a strong smectic liquid crystal is formed in the space sandwiched between the alignment films 4a and 4b from the injection port. Dielectric liquid crystal 6 is injected, and the injection port is sealed with sealant 5. The two glass substrates 2a and 2b thus bonded together are sandwiched by two polarizing plates 7a and 7b arranged so that their polarization axes are orthogonal to each other.

The material of the ferroelectric liquid crystal 6 used in this example is the FLC mixture SCE8 manufactured by Merck & Co., Ltd. to which 10 wt% of the achiral liquid crystal compound 1 is added, and the alignment film 4 is used.
a and 4b are PSI-A-2101 manufactured by Chisso Corporation.
The temperature characteristic of voltage-response speed of this FLC panel is as shown in FIG.

FIG. 3 is a plan view showing a schematic structure of the FLC panel. In this figure, each of the scanning electrodes L is distinguished by adding a subscript i (i = 0 to F) to the code L, and each of the signal electrodes S is added to the code S by a subscript j (j = 0 to F). To distinguish. Further, in the following description, a pixel at a portion where an arbitrary scan electrode Li and an arbitrary signal electrode Sj intersect is represented by a symbol Aij.

As shown in the figure, the scanning electrode L of the FLC panel 1 is connected to the scanning side drive circuit 8, and the signal electrode S is connected to the signal side drive circuit 9.

The scanning side driving circuit 8 is a circuit for applying a voltage to the scanning electrode L, and is composed of a shift register 10a, a latch 11a and an analog switch 12a, and Y
0 and Y1 signals, select voltage VC1, non-select voltage VC
0 or the temperature compensation voltage VC2 is applied to the scan electrode L.
Apply to.

The signal side drive circuit 9 is a circuit for applying a voltage to the signal electrode S, and the shift register 10
b, a latch 11b, and an analog switch 12b, for example, when displaying black, the black rewriting voltage VS
When 1 is applied and white is displayed, the white rewriting voltage VS
0 is applied.

FIG. 4 is a block diagram showing a schematic structure of an FLC display device including a temperature detection circuit for driving an FLC panel by the driving method of the present invention.

In this figure, 1 is an FLC panel, 22
Is a temperature sensor provided in the FLC panel 1, 23 is a temperature compensation circuit that outputs an application timing signal of a temperature compensation voltage based on the temperature detected by the temperature sensor 22, 2
Reference numeral 4 denotes a memory circuit that stores and holds waveform pattern data for forming a scanning voltage waveform and a signal voltage waveform in an even number of n bits, and 25 denotes a signal of the temperature compensation circuit 23 and the memory circuit 2.
4 is a drive voltage waveform control circuit for applying a drive voltage waveform to the FLC panel 1 based on the signal from the signal No. 4. The drive voltage waveform control circuit 25 includes the scan side drive circuit 8 and the signal side drive circuit 9 described above.

The temperature compensation of this embodiment compensates for the voltage-response speed characteristic of the liquid crystal material in the FLC panel 1 which changes with temperature.

In this FLC display device, a temperature compensation voltage waveform having a polarity opposite to that of the selection voltage waveform is multiplied by m (m is a real number of 0 or more) times the slot time (t) adjusted according to the temperature change.
s) is applied to the scanning electrodes L at intervals,
It is possible to drive the FLC panel 1 and perform temperature compensation. Hereinafter, this driving method will be referred to as a compensation voltage separate application driving method.

A driving method for sequentially reading the applied voltage signal from the memory circuit 4 in which the waveform pattern data forming the scanning voltage waveform and the signal voltage waveform is stored and held in even n (n is an even integer) bits, The scanning voltage waveform is
The number i of bits smaller than n forming the first voltage (i is an even integer smaller than n) is zero voltage, and the (n−i) bits forming the second voltage is voltage | V1 | In the voltage waveform, the i bit forming the first voltage is the voltage | V
0 | constitutes the second voltage, and the (n / 2) bit constituting the third voltage is the voltage | V0 | having the opposite polarity to the first voltage.
/ 2-i) The bit is a voltage | V0 | having the same polarity as the first voltage, and the FLC panel 1 can be driven and temperature compensation can be performed by a driving method in which the value of i is adjusted by a temperature control signal or the like. It is possible. Hereinafter, this driving method is referred to as a compensation voltage synthesis application driving method.

Furthermore, it is possible to drive the FLC panel 1 and perform temperature compensation by combining both of the above-mentioned separate driving method of compensation voltage and driving method of combined compensation voltage. Hereinafter, this driving method is referred to as a compensation voltage combination application driving method.

When this FLC display device is used to drive the FLC panel 1 by the method of separately applying compensation voltage,
The memory circuit 24 is not used, but the temperature compensation circuit 23 and the drive voltage waveform control circuit 25 are used.

That is, the signal from the temperature sensor 22 provided in the FLC panel 1 is transmitted to the temperature compensation circuit 23,
Here, after converting to the temperature compensation parameter set in advance, the timing signal for applying the temperature compensation voltage is transmitted to the drive voltage waveform control circuit 25, and based on this, the drive voltage waveform control circuit 25 drives the FLC panel 1 to drive voltage. Give a waveform.

When the FLC panel 1 is driven by this FLC display device by the compensation voltage synthesis application driving method, the temperature compensation circuit 23, the memory circuit 24, and the drive voltage waveform control circuit 25 are used.

That is, the signal from the temperature sensor 22 provided in the FLC panel 1 is transmitted to the temperature compensation circuit 23,
The temperature compensation circuit 23 controls the output waveform from the memory circuit 24. That is, in the memory circuit 24,
The voltage VC and the voltage VS supplied to the analog switches 12a and 12b of the scanning side driving circuit 8 and the signal side driving circuit 9.
Since the output voltage pattern is held, the output voltage pattern is controlled by the temperature compensating circuit 23, and the driving voltage waveform is applied from the driving voltage waveform control circuit 25 to the FLC panel 1 based on this.

Further, when the FLC panel 1 is driven by the compensation voltage combination application driving method using this FLC display device, the temperature compensation circuit 23, the memory circuit 24 and the drive voltage waveform control circuit 25 are used to drive the drive voltage. The waveform control circuit 25 provides the FLC panel 1 with a drive voltage waveform that is a combination of the separate compensation voltage application drive method and the compensation voltage composite application drive method.

5 and 6 are waveform diagrams showing voltage waveforms applied to the scanning electrodes, the signal electrodes and the pixels when the FLC panel is driven by the separate compensation voltage driving method. Figure 5
Shows a voltage waveform for black rewriting, and FIG. 6 shows a voltage waveform for white rewriting.

As shown in these figures, at the time of black rewriting, for the scanning electrode L, the selection voltage waveform of (1) of FIG. 5 is selected during the selection period, and the selection voltage waveform of (2) of FIG. 5 is selected during the non-selection period. As the non-selection voltage waveform, the temperature compensation voltage waveform of (3) in FIG. 5 is applied during the temperature compensation period.

The period until the temperature compensating voltage waveform of (3) in FIG. 5 is applied is determined by the temperature compensating circuit 23 shown in FIG. A drive voltage waveform and a temperature compensation voltage waveform are given to.

Further, at the time of white rewriting, for the scanning electrode L, the selection voltage waveform of (1) of FIG. 6 is selected during the selection period, and the non-selection voltage waveform of (2) of FIG. 6 is selected during the non-selection period. During the temperature compensation period, the temperature compensation voltage waveform of (3) in FIG. 6 is applied.

Then, the period until the temperature compensating voltage waveform of (3) in FIG. 6 is applied is determined by the temperature compensating circuit 23 shown in FIG. 4, and is controlled by the drive voltage waveform controlling circuit 25 to make the FLC panel. 1, the drive voltage waveform and the temperature compensation voltage waveform are given.

As described above, the voltage waveform shown in FIG. 5 is used for black rewriting and the voltage waveform shown in FIG. 6 is used for white rewriting, so that F
The LC panel 1 can be rewritten with the target pixel information.

Here, (3) in FIG. 5 and (3) in FIG.
The temperature compensation voltage waveform indicated by is a voltage equal to or lower than the threshold value that changes the pixel state. Further, in the present embodiment, the temperature compensation voltage waveform is applied before the selection voltage waveform, but it may be applied after the selection voltage waveform depending on the temperature compensation situation.

FIG. 7A shows a drive voltage waveform on the scanning signal side that is actually applied to the pixel Aij when the present FLC display device is operated using the main drive voltage waveform. Using the drive voltage waveform of FIG. 7A, when the temperature rises, the interval m × ts (ts: slot pulse width, m is a real number of 0 or more) with the temperature compensation voltage waveform is reduced. , When the temperature becomes low, the distance m × t from the temperature compensation voltage waveform
This FLC display device was operated by increasing s.

When the present FLC display device is operated in this manner, driving conditions can be obtained in a wide operating temperature range of 5 ° C. or more on the high temperature side, as compared with a normal driving method without a temperature compensation voltage. It was

[Embodiment 2] The FLC display device used in this embodiment is the same as that in Embodiment 1. The method for separately applying the compensation voltage according to the first embodiment excludes the temperature compensation voltage.
However, the effect of the temperature compensation voltage is not limited to this driving method, and in the driving method using the blanking pulse described in JP-A-5-249434. Was also applicable. This drive voltage waveform is shown in FIG.

The temperature compensation voltage waveform applied here is a voltage equal to or lower than the threshold value for changing the pixel state. Further, this temperature compensation voltage waveform is applied before or after the selection voltage waveform depending on the situation of temperature compensation.

Using the drive voltage waveform of FIG. 7B, when the temperature rises, the distance m from the temperature compensation voltage waveform is m.
When × ts is decreased and the temperature is lowered, the interval m × ts with the temperature compensation voltage waveform is increased and the FLC display device is operated. As a result, a normal driving method using no temperature compensation voltage is used. Compared with, it was possible to obtain a wider driving condition than 3 ° C.

After the selection period (after applying the selection voltage waveform)
If the FLC material does not need to use the temperature compensation voltage, the blanking pulse itself is used as the temperature compensation voltage.
The blanking interval can be adjusted by the temperature compensation circuit 23 shown in FIG.

As described above, when the blanking pulse itself is used as the temperature compensation voltage, the temperature compensation voltage waveform to be applied has a pulse width and an amplitude value equal to or more than the threshold value for rewriting the entire pixel into one stable state. It was done.

[Embodiment 3] FIGS. 8 and 9 are waveform charts showing voltage waveforms applied to the scanning electrodes, the signal electrodes and the pixels when the FLC panel is driven by the compensation voltage synthesis application driving method. FIG. 8 shows a voltage waveform for rewriting the signal side voltage waveform applied to the signal electrode, and FIG. 9 shows a voltage waveform for non-rewriting. The FLC display device used in this example is the same as that in Example 1, and therefore its description is omitted.

In this compensating voltage composition application driving method, the temperature compensating circuit 23 holds the waveform patterns of the voltage VC and the voltage VS supplied to the analog switches 12a and 12b of the scanning side driving circuit 8 and the signal side driving circuit 9. The output pattern of the operating memory circuit 24 is controlled.

That is, in this compensation voltage synthesis application driving method, the scanning voltage waveform has a bit number i smaller than n forming the first voltage and having a voltage of zero, and (n−i) bits forming the second voltage. Is the voltage | V1 |, and the signal voltage waveform is such that the i bit forming the first voltage has the voltage | V0 |
Then, the (n / 2) bit forming the second voltage is a voltage | V0 | having a polarity opposite to that of the first voltage and forming a third voltage (n / 2).
-I) The bit is a voltage | V0 | having the same polarity as the first voltage, and the value of i that determines the applied waveform pattern is close to n at high temperatures and close to 0 at low temperatures.

Specifically, as shown in FIGS. 8 and 9, the waveform pattern data of the selected time width is decomposed into 24 bits and held, and the drive voltage waveform pattern is converted into the waveform pattern (a ) -Wave pattern (e) can be changed.

When the driving temperature is low, the pattern of the driving voltage waveform is brought close to the waveform pattern (a), and when the driving temperature is high, the waveform pattern data is shifted and rotated to change the driving voltage waveform pattern. , So as to be close to the waveform pattern (e).

However, the waveform pattern (e) is not actually used because the driving condition cannot be obtained because the waveform does not exist on the scanning side electrode. In this embodiment, 4 out of 24 bits
It could not be driven unless the voltage V1 was more than a bit. The driving voltage waveform actually applied to the pixel Aij is shown in FIG.

By using the temperature-compensated drive voltage waveform including FIG. 10, even if the temperature changes, the operating temperature range of 5 ° C. or more can be maintained as compared with the conventional drive method in which only the waveform of the waveform pattern (c) is used. I was able to spread it.

[Embodiment 4] In the present embodiment, the FLC display device of the present invention is used to perform FL with a compensation voltage combination application driving method.
C panel 1 was driven. That is, the temperature compensation circuit 23 is used by simultaneously using the separate compensation voltage driving method used in the first embodiment and the compensation voltage synthesis application driving method used in the third embodiment.
Using the memory circuit 24 and the drive voltage waveform control circuit 25, the drive voltage waveform control circuit 25 provides the FLC panel 1 with a drive voltage waveform that is a combination of the separate compensation voltage application drive method and the compensation voltage composite application drive method. It was

Specifically, the applied voltage waveform (1), the applied voltage waveform (4) and the applied voltage waveform (5) shown in FIGS.
Are applied voltage waveforms (1) of FIG. 8 and FIG. 9, respectively.
When the temperature rises by replacing the applied voltage waveform (2a) and the applied voltage waveform (2b), the interval m × ts with the temperature compensation voltage waveform is reduced, and the applied voltage waveform is a waveform pattern (e). When the temperature becomes low, the interval m × ts from the temperature-compensated voltage waveform is increased, and the applied voltage waveform is brought close to the waveform pattern (a). Compared with the conventional drive method without compensation, without changing the drive voltage or drive frequency,
It was possible to widen the operating temperature range of 10 ° C. or higher. When the drive frequency adjustment was also used, the drive frequency could be suppressed about twice as much in the high temperature part as compared with the case where the temperature compensation method of the present invention was not used, and the power consumption and heat generation problems could be improved.

[0073]

According to the present invention, in the high temperature range,
It is possible to suppress an increase in driving voltage and an increase in driving frequency, improve power consumption and heat generation, and improve display quality and durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of an FLC panel used in a driving method of the present invention.

FIG. 2 is a graph (τ-Vmin) showing temperature characteristics of voltage-response speed of the FLC panel used in the driving method of the present invention.
It is a characteristic diagram which shows the temperature dependence of a curve.

FIG. 3 is a plan view showing a schematic configuration of an FLC panel used in the driving method of the present invention.

FIG. 4 is a block diagram showing a schematic configuration of an FLC display device including a temperature detection circuit for driving an FLC panel by the driving method of the present invention.

FIG. 5 is a waveform diagram showing voltage waveforms applied to the scan electrodes, the signal electrodes and the pixels when the FLC panel is driven by the separate compensation voltage driving method of the present invention.

FIG. 6 is a waveform diagram showing voltage waveforms applied to the scan electrodes, the signal electrodes and the pixels when the FLC panel is driven by the separate compensation voltage driving method of the present invention.

FIG. 7 is a waveform diagram showing a driving voltage waveform on the scanning signal side that is actually applied to a pixel when the FLC display device is operated by the separate compensation voltage driving method of the present invention.

FIG. 8 is a waveform diagram showing voltage waveforms applied to a scanning electrode, a signal electrode and a pixel when a FLC panel is driven by the compensation voltage synthesis application driving method of the present invention.

FIG. 9 is a waveform diagram showing voltage waveforms applied to the scan electrodes, the signal electrodes and the pixels when the FLC panel is driven by the compensation voltage synthesis application driving method of the present invention.

FIG. 10 shows a FLC according to the compensation voltage synthesis application driving method of the present invention.
FIG. 9 is a waveform diagram showing a driving voltage waveform on the scanning signal side that is actually applied to a pixel when the display device is operated.

FIG. 11 is a graph showing temperature characteristics of voltage-response speed of a FLC panel in a conventional example (characteristic diagram showing temperature dependence of τ-Vmin curve).

[Explanation of symbols]

 1 FLC panel 2a, 2b Glass substrate 3a, 3b Insulating film 4a, 4b Alignment film 5 Sealant 6 Ferroelectric liquid crystal 7a, 7b Polarizing plate 8 Scanning side driving circuit 9 Signal side driving circuit 10a, 10b Shift register 11a, 11b Latches 12a, 12b Analog switch 22 Temperature sensor 23 Temperature compensation circuit 24 Memory circuit 25 Drive voltage waveform control circuit L Scan electrode S Signal electrode

Claims (8)

[Claims] 1. A pixel is formed by interposing a ferroelectric smectic liquid crystal having two stable states at each intersection of a scanning electrode and a signal electrode arranged in a direction intersecting with each other to form image information data. A method of driving a ferroelectric liquid crystal display panel, wherein a signal voltage based on the above is applied to a signal electrode, and a scanning voltage having a selection voltage waveform or a non-selection voltage waveform is applied to the scanning electrode in synchronization with the signal voltage. Before or after the selection voltage is applied, a temperature compensation voltage having a waveform having a polarity opposite to that of the selection voltage is applied to the scanning electrode at a certain time with respect to the selection time, and the liquid crystal changes depending on the temperature. A method for driving a ferroelectric liquid crystal display panel, characterized by compensating for the response of the device. 2. The ferroelectric liquid crystal display panel according to claim 1, wherein the time lag of the temperature compensation voltage with respect to the application timing of the selection voltage is set shorter when the temperature of the liquid crystal is higher and longer when the temperature of the liquid crystal is lower. Driving method. 3. The method for driving a ferroelectric liquid crystal display panel according to claim 1, wherein the waveform of the temperature compensation voltage has an amplitude value equal to or less than a threshold value for changing a pixel state. 4. The method for driving a ferroelectric liquid crystal display panel according to claim 1, wherein the waveform of the temperature compensation voltage has a pulse width and an amplitude value which are equal to or more than a threshold value for rewriting the pixel state into one stable state. 5. A pixel is constructed by interposing a ferroelectric smectic liquid crystal having two stable states at each intersection of a scanning electrode and a signal electrode arranged in a direction intersecting with each other, thereby forming image information data. A driving method of a ferroelectric liquid crystal display panel, wherein a signal voltage based on the above is applied to a signal electrode, and a scanning voltage having a selection voltage waveform or a non-selection voltage waveform is applied to the scanning electrode in synchronization with the signal voltage. , A voltage having a waveform consisting of a first period in which the selection period is zero voltage and a second period of a predetermined voltage is applied, and at least two voltages, that is, a first voltage and a second voltage of opposite polarity to the signal electrode, are applied to the signal electrode. Is applied to synchronize the switching timing of the first voltage and the second voltage with the end of the first period of the scanning voltage, and the switching timing of this voltage is changed by an external signal. of Dynamic way. 6. The method of driving a ferroelectric liquid crystal display panel according to claim 5, wherein the switching timing of the first voltage and the second voltage is adjusted according to the temperature change when the voltage is applied. 7. The time from the start of the selection period to the timing of switching between the first voltage and the second voltage is longer as the temperature is higher,
7. The method for driving a ferroelectric liquid crystal display panel according to claim 6, wherein the lower the value, the shorter the adjustment. 8. A ferroelectric liquid crystal display panel is driven by using the method for driving a ferroelectric liquid crystal display panel according to claim 1 and the method for driving a ferroelectric liquid crystal display panel according to claim 5 at the same time. A method for driving a ferroelectric liquid crystal display panel, which is characterized by: