JPH09197379A - Method for driving liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal driving method capable of extending the driving margine without increasing the voltage value of information signal. SOLUTION: An information signal and a scanning signal are selectively impressed to many pixels forming a display screen to switch the pixels. A control part 43 controls the pulse generating operation of a separation pulse generating part 42 to generate a separation pulse Ps and a writing pulse Pw generated from a writing pulse generating part 42 is separated by the separation pulse Ps. Thus, synthetic waveform between the information signal and the writing pulse Pw includes a reverse polarity pulse and the switching operation of unselected pixels is interrupted without increasing the voltage value of the information signal.

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 liquid crystal element, and more particularly to a method of driving a liquid crystal element by matrix driving.

[0002]

2. Description of the Related Art Conventionally, there has been known a liquid crystal device having a structure in which a chiral smectic liquid crystal which is a ferroelectric liquid crystal is filled between a pair of substrates in which an information signal electrode group and a scanning signal electrode group are formed in a matrix. In many cases, a voltage modulation method is adopted as a driving method of such a liquid crystal element.

In such a voltage modulation method, the scanning write pulse Pw shown in (1) of FIG. 11 is applied to the scanning signal electrode group, and the information on signal or the information off signal shown in (2) is used as an information signal. By applying each to the electrode group, the ON combined waveform or the OFF combined waveform shown in (3) is selectively applied to a large number of pixels forming the display screen,
Writing or non-writing in each pixel is determined depending on whether or not these combined waveforms exceed a threshold value. Regarding the driving method of such a liquid crystal element,
For example, JP-A-60-229012 and JP-A-60-229012.
-250332 and the like.

On the other hand, FIG. 12 is a diagram showing specific scanning waveforms and the like in this voltage modulation method. The scanning signal shown in (1) and the information on signal and information off signal shown in (2) of FIG. By applying each to the scanning signal electrode group and the information signal electrode group, the ON or OFF combined waveform shown in (3) is applied to the pixel, and when the combined waveform exceeds the threshold value, the liquid crystal element is driven. It has become.

The scanning signal shown in (1) of FIG.
An erasing pulse Pe is applied prior to a writing pulse (hereinafter referred to as a scanning writing pulse) Pw of a scanning signal, so that after erasing in one direction of two stable states, writing in another direction is performed. It is determined by the pulse Pw. Then, by multiplexing this write waveform, n × m simple matrix drive becomes possible.

[0006]

By the way, in order to obtain a good image quality in the entire display area of the liquid crystal element, variations in driving characteristics or threshold characteristics due to cell thickness unevenness, alignment unevenness, drive waveform delay, etc. are sufficiently suppressed. You must design the display creation process to do so. Then, in this display production process, if the drive waveform has the ability to have a wide drive margin, the precision in the production process is relaxed and the productivity is improved.

On the other hand, this drive margin is determined by the voltage ratio of the write pulse of the composite waveform. Therefore, in the conventional liquid crystal element driving method, the ratio of the ON waveform to the OFF waveform is increased by increasing the voltage value of the information signal relative to the scanning signal, thereby increasing the driving margin. I was doing. However, when the voltage value of the information signal is increased in this way, not only the power consumption increases but also the voltage value in the non-selected state increases, which causes a problem that the contrast decreases and high image quality cannot be realized.

Therefore, the present invention has been made in order to solve such a problem, and provides a driving method of a liquid crystal element capable of widening a driving margin without increasing a voltage value of an information signal. It is in.

[0009]

According to the present invention, liquid crystal is filled between a pair of substrates, and the substrates are selectively provided with information signals and scanning signals for a large number of pixels forming a display screen. In a method of driving a liquid crystal element in which an information signal electrode group to be applied and a scanning signal electrode group are formed in a matrix, a writing pulse of a scanning signal sequentially applied to the scanning signal electrode group is divided. However, the combined waveform of the information signal and the writing pulse applied to the information signal electrode group in synchronization with the scanning signal includes a reverse polarity pulse.

Further, according to the present invention, liquid crystal is filled between a pair of substrates, and information signals and electrodes for selectively applying information signals and scanning signals to a large number of pixels forming a display screen are provided on the substrates. In a method of driving a liquid crystal element in which a group and a scanning signal electrode group are formed in a matrix, a scanning signal control means for sequentially applying a scanning signal having a writing pulse to the scanning signal electrode group, An information signal control means for applying an information signal to the information signal electrode group in synchronization with the scanning signal; a dividing pulse generating means for generating a dividing pulse for dividing the writing pulse; and a dividing pulse for dividing the writing pulse. A control means for controlling the pulse generation operation of the division pulse generation means, and the combination with the information signal by dividing the write pulse by the division pulse. In which waveform is characterized in that it comprises a reverse polarity pulse.

Further, the present invention is characterized in that the voltage value of the dividing pulse is smaller than the voltage value of the write pulse.

Further, the present invention is characterized in that the pulse width of the dividing pulse is smaller than the pulse width of the write pulse.

Further, the present invention is characterized in that the pulse width of the information signal is smaller than the pulse width of the write pulse and larger than the pulse width of the division pulse.

Further, the present invention is characterized in that the pulse crest value of the divided pulse is smaller than the pulse crest value of the information signal.

Further, the present invention is characterized in that the liquid crystal is a chiral smectic liquid crystal which is a ferroelectric liquid crystal.

The present invention is also characterized in that the liquid crystal is a chiral smectic liquid crystal which is an antiferroelectric liquid crystal.

The present invention is also characterized in that the scanning signal has an erase pulse.

Further, the present invention is characterized in that the scanning signal sets the scanning writing pulse in the first half and the latter half of the writing period.

With this structure, the scanning signal control unit sequentially applies the scanning signal having the write pulse to the scanning signal electrode group, and the information signal electrode group receives the scanning signal by the information signal control unit. The information signal is applied in synchronization with. Then, these information signals and scanning signals are selectively applied to a large number of pixels forming a display screen to switch the pixels. Further, the control means controls the pulse generation operation of the divided pulse generation means to generate a divided pulse, and the write pulse is divided by this divided pulse, whereby a composite waveform of the information signal and the write pulse is generated. The reverse polarity pulse is included so that the switching operation of the unselected pixel is disturbed.

Further, by setting the voltage value of the divided pulse to be smaller than the voltage value of the write pulse, the combined waveform of the information signal and the write pulse includes a reverse polarity pulse.

Further, by making the pulse width of the dividing pulse smaller than the pulse width of the writing pulse, the scanning writing pulse can be surely divided.

Further, by making the pulse width of the information pulse smaller than the pulse width of the write pulse and larger than the pulse width of the divided pulse, the combined waveform of the information signal and the write pulse includes a reverse polarity pulse. In addition, the contrast of the information signal when not selected is improved.

Further, the pulse crest value of the divided pulse is set to be smaller than the pulse crest value of the information signal so that the composite waveform of the information signal and the writing pulse includes a pulse of opposite polarity.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a liquid crystal display circuit to which the method for driving a liquid crystal element according to the present invention is applied. In FIG. 1, 1 is a video RAM (VRAM) for storing image information.
The image display data D1 is transferred from the graphic controller 1 to the drive control circuit 3 according to the transfer clock CL.

On the other hand, the image display data D1 from the graphic controller 1 is input to the scanning signal control circuit 4 which is the scanning signal control means of the drive control circuit 3 and the information signal control circuit 5 which is the information signal control means, respectively. The scan signal address data D2 and the display data D3 are converted.

Then, these scan signal address data D
2 and the display data D3, the scanning signal driver 6
The information signal driver 7 applies the scanning signal and the information signal to the information signal electrode group 10 and the scanning signal electrode group 11 which are formed in a matrix of the display unit 9 of the liquid crystal element 8, and thereby the display unit. Nine predetermined pixels respond to display an image. In addition, each drive voltage V is
It is generated by the drive voltage generation circuit 12.

By the way, in this embodiment, an element using a chiral smectic liquid crystal exhibiting ferroelectricity or antiferroelectricity can be used as the liquid crystal element 8. Further, the surface-stabilized ferroelectric liquid crystal element which exhibits optical bistability includes, for example, as shown in FIG. 2, in addition to the information signal electrode group 10 and the scanning signal electrode group 11, a polarizing plate 81,
A glass substrate 82, a chiral smectic liquid crystal 83 which is a ferroelectric liquid crystal filled between the glass substrates 82, 82,
It is composed of a retardation plate 84, a pixel electrode 85, and the like.

The main physical properties of an example of the liquid crystal 83 used in this ferroelectric liquid crystal panel are as follows.

Spontaneous polarization 7 nC / cm 2 (30 ° C.) Tilt angle 15 deg Phase transition temperature −10 ° C. SmC *, 65 ° C. SmA, 8
0 ° C Ch, 95 ° C ISO By the way, the ferroelectric liquid crystal 83 is adapted to perform switching in response to the polarity of the applied pulse, but this switching operation is promoted if pulses of the same polarity continue. , Blocked when a pulse of opposite polarity is applied. From this, the drive margin can be dramatically improved by introducing the reverse polarity pulse into the waveform which is not desired to be switched.

Therefore, in the present invention, (1) in FIG.
As shown in, the central portion of the scanning write pulse Pw applied to the scanning signal electrode group 11 is divided by the dividing pulse Ps. Then, since the scan write pulse Pw divided in this way is applied to the scan signal electrode group 11, in the present embodiment, a write pulse for generating the scan write pulse Pw in the scan signal control circuit 4 as shown in FIG. The generation unit 41, the division pulse generation unit 42 that is a separation pulse generation unit that generates the division pulse Ps, and the pulse generation operation of the write pulse generation unit 41 and the division pulse generation unit 42 so as to divide the scan write pulse Pw at the central portion. And a control section 43 which is a control means for controlling the. The control unit 43 may be provided outside the scanning signal control circuit 4.

By the way, (1) of FIG. 5 shows a scanning signal waveform having the scanning writing pulse Pw divided at the central portion, and in (1), ΔT is the pulse width of the scanning writing pulse Pw, Vw indicates the pulse peak value, and Ts indicates the pulse width of the divided pulse Pw.

Here, the pulse width T of this divided pulse Pw
s is smaller than the pulse width ΔT of the scan write pulse Pw.

Further, the pulse peak value Vs of the divided pulse Pw
(0V in FIG. 5) is smaller than the pulse crest value Vw of the scanning write pulse Pw, and even when the information-on signal as shown in (2) of FIG. The polarity does not change in the ON combined waveform shown in (3). Then, by preventing the polarity from changing in the ON combined waveform in this way, the same polarity pulse can be continuously applied to the pixel to be switched (selected), and the switching operation can be performed. Can be promoted.

On the other hand, the information signal electrode group 10 is adapted to be applied with the information on signal or the information off signal shown in (2) of FIG. 3, and the pulse peak value of this information signal is shown in FIG. If Vd as shown in 2), the divided pulse P
The pulse peak value Vs of w is smaller than the pulse peak value Vd of the information signal.

By setting Vd> Vs in this way, when an information off signal as shown in (2) of FIG. 3 is applied, the divided pulse of the off combined waveform shown in (3) of FIG. 3 is obtained. The polarity can be changed by Pw. This makes it possible to apply a pulse of opposite polarity to pixels that are not desired to be switched (not selected), and hinder the switching operation.

Therefore, when the scan write pulse Pw is divided by the division pulse Pw and the information signal is applied in synchronization with the division pulse Pw, the pixel has only the same polarity pulse as shown in (3) of FIG. The composite waveform is applied, but since the OFF composite waveform includes the reverse polarity pulse Pr, the switching operation of the unselected pixel is strongly hindered.

As described above, the drive margin is not sufficient because the effect of only the voltage modulation is conventionally used, but in addition to the voltage modulation effect as in the present invention, the dividing effect by the reverse polarity pulse Pr in the OFF combined waveform is obtained. Since the driving margin can be widened without increasing the voltage value of the information signal, it is possible to obtain a very wide driving margin as compared with the conventional example shown in FIG. Then, by obtaining such a wide driving margin, it is possible to sufficiently allow variations in driving characteristics or threshold characteristics due to cell thickness unevenness, alignment unevenness, driving waveform delay, and the like.
Productivity can be improved.

FIG. 6 is a diagram showing drive waveforms according to the first example of the present embodiment utilizing this principle. (1) in FIG. 6 shows three scanning signal electrode groups 11 shown in FIG. It shows that the scanning signals as shown in (1) of FIG. 5 are sequentially applied to the lines 11a, 11b, and 11c. In this scanning signal, the pulse width of the dividing pulse Ps is 8: 1 with respect to the pulse width of the scanning writing pulse Pw, and this ratio may be changed according to the characteristics of the liquid crystal.

Further, (2) shows an information signal applied to one line 10a of the information signal electrode group 10 in synchronism with this scanning signal, and (3) shows 2 by this information signal.
The waveform of the applied voltage applied to the two lines 11a and 11b is shown. Note that this driving method is a method in which information is written after erasing information for each common line. By thus introducing the erase pulse Pe before the information writing, the two states can be discriminated from each other.
By the way, the scan write pulse P divided in this way
By using w, the same polarity pulse is continuously applied to the line 11a to which the information signal is applied as shown in (3), and the switching operation of the selected pixel is promoted. However, the pulse of the opposite polarity is applied to the pixel on the line 11b which is not desired to be switched, and the switching operation is hindered.

Then, by configuring in this way,
For example, when the drive margin under the condition that the 1-line selection period is 60 μSec and the ratio of the segment voltage to the common voltage is ⅓, the common voltage of the conventional waveform shown in (3) of FIG. 12 is 9V to 15V. On the other hand, in the present embodiment, a good quality image can be obtained even when the common voltage is changed from 10V to 22V.

Therefore, in this way, the scan write pulse P
By dividing w, the common voltage width that can be changed is 12V (22V-10V), which is twice the conventional 6V (15V-9V), and a wide drive margin can be obtained. Further, since such a wide drive margin is obtained, the allowable range of each variation is widened and the productivity is improved.

By the way, FIG. 7 is a diagram showing drive waveforms according to the second example of the present embodiment. In FIG.
(1) shows a scanning waveform, (2) shows an information on signal and an information off signal, and (3) shows an on combined waveform and an off combined waveform. Incidentally, the scanning waveform shown in (1) of the figure does not have an erasing pulse but has a pulse Pw ′ for writing each state.

Then, when the driving margin is examined under the same driving condition as that of the above-described first embodiment, that is, the one-line selection period of 60 μSec and the ratio of the segment voltage to the common voltage of 1/3, the common voltage is found. It can be changed from 8V to 16V. That is, the common voltage range that can be changed is 8 V, which is 1.3 times the conventional 6 V, and a wide drive margin and good image quality can be obtained.

FIG. 8 is a diagram showing drive waveforms according to the third example of the present embodiment. In FIG. 8, (1) shows a scanning waveform, and (2) shows an information-on signal and an information-off signal. ,
(3) shows an ON combined waveform and an OFF combined waveform.
The pulse width Td of the information signal shown in (2) of FIG.
It is set to be smaller than the pulse width ΔT of the scan write pulse Pw and larger than the pulse width Ts of the division pulse Pw. Then, by setting the information signal pulse width Td in this way, the effective value of the information signal in the non-selected state is reduced, and accordingly, the power consumption is reduced and the contrast is further improved.

In the first embodiment described above, the contrast was 50, but in the present embodiment, it was improved to 70. Further, comparing drive margins under the same drive conditions as in the above-described first embodiment, the common voltage is 10V to 1V.
The voltage difference can be changed to 7 V, and the voltage difference is 7 V, which is 1.2 times the conventional 6 V, and a wide drive margin and good image quality can be obtained.

Further, FIG. 9 is a diagram showing a driving waveform according to a fourth example of the present embodiment, in which FIG.
Shows a scanning waveform, (2) shows an information on signal and an information off signal, and (3) shows an on combined waveform and an off combined waveform. As shown in (1) of the figure, the scanning signal has erase pulses Pe simultaneously provided for three lines 11a, 11b, and 11c (see FIG. 1), each having a scanning write pulse Pw.

When the driving margin is examined under the same driving condition, the common voltage can be changed from 10V to 20V, and the voltage difference is 1.7 times that of the conventional 6V.
Since it is 0 V, a wide drive margin and good image quality can be obtained.

Even if the erasing pulse is provided for 64 lines at the same time, the driving margin is from 10V to 20V of the common voltage, and a wide driving margin and good image quality can be obtained.

Further, FIG. 10 is a diagram showing a driving waveform according to a fifth example of the present embodiment, which is an example suitable for a method of driving an antiferroelectric liquid crystal. In the figure, (1) is four lines 11a, 11b, 11c of the scanning signal electrode group 11,
11d (see FIG. 1), the scanning waveform sequentially applied,
(2) shows the information on signal and the information off signal,
The composite waveform is not shown. In the scanning waveform shown in (1), the scanning writing pulse Pw is set in the first half and the latter half of the 1-line writing period. Further, in the case of anti-ferroelectric liquid crystal, it is common to apply an offset voltage V _OFF when it is not selected and invert it for each frame.
Also in this embodiment, the frame inversion is adopted. Further, in the embodiment, the liquid crystal material “CS4000” manufactured by Chisso Corporation is used, and the panel has 320 × 240 pixels.

When the device was driven under the conditions of such a holding voltage of 15 V, a writing voltage of 30 V, and a writing pulse width of 150 μs, a good image was obtained.

Next, a sixth embodiment for driving a ferroelectric liquid crystal panel using the liquid crystal display circuit shown in FIG. 1 will be described. Here, the main physical property values of the liquid crystal used in this ferroelectric liquid crystal panel are the same as those described above.

The specification of the liquid crystal panel is 1024 × l.
280 pixels, 230 um pitch, effective pixel area diagonally 14.8 inches, pixel configuration 16 colors / pixel, frame frequency 15 Hz, no interlace.

Here, the ferroelectric liquid crystal panel is driven with the matrix driving waveform shown in FIG. In this embodiment, the division pulse is 8: with respect to the write palace width.
It is one. Then, a scanning signal is sequentially applied to the three lines 11a, 11b, 11c of the scanning signal electrode group 11, and a desired information signal is applied in synchronization with it. In this driving, a method of writing after erasing for each common line is adopted, and by introducing an erasing pulse before writing in this way, it is possible to distinguish between two states.

By using this waveform, one line selection period is 60 μsec, and segment voltage / common voltage is 1 /
Under the condition of No. 3, good image quality could be obtained even when the common voltage was changed to 10 to 22V.

On the other hand, in contrast, when the drive margin in the waveform of FIG. 12 described above was examined under the same drive conditions as in this embodiment, the drive margin was a common voltage of 9 to 15V.

Therefore, according to this embodiment, the drive margin width is about 1.5 times, and a wide drive margin can be obtained.
The tolerance range for each variation has expanded and productivity has improved.

Next, a seventh embodiment using the waveform shown in FIG. 5 will be described. Here, unlike the waveform of the sixth embodiment, the waveform of FIG. 5 does not have an erase phase but has a phase for writing each state. This embodiment is the same as the seventh embodiment except that the waveform is changed.

When the drive margin was examined under the same drive conditions as in the sixth embodiment, the drive margin was from 8 to 16 V of common voltage, and a wide drive margin and good image quality were obtained.

Next, an eighth embodiment using the waveform shown in FIG. 8 will be described. Here, unlike the waveform of the sixth embodiment, the waveform shown in FIG. 8 is set so that the pulse width of the information signal is smaller than that of the scanning signal. With such a configuration, the effective value at the time of non-selection is reduced, so that the power consumption is reduced and the contrast is further improved.

That is, the contrast was 50 in the sixth embodiment, but improved to 70 in the present embodiment. In addition,
When the drive margin was examined under the same drive conditions as in the sixth embodiment, the drive margin was from 10 to 17 V for the common voltage, and a wide drive margin and good image quality were obtained.

Next, a ninth embodiment using the waveform shown in FIG. 9 will be described. Here, the waveform shown in FIG. 8 is different from the waveform of the sixth embodiment in that the erase phase is provided for three lines at the same time and each phase has a writing phase. When the drive margin was examined under the same drive conditions as in the sixth embodiment, the drive margin was a common voltage of 10 to 20 V, and a wide margin and good image quality were obtained.

It should be noted that instead of providing the erasing phase for 3 lines at the same time, the erasing phase may be provided for 64 lines at the same time.
When the drive margin was examined under the same drive conditions as in Example 1, the drive margin was a common voltage of 10 to 20 V, and a wide drive margin and good image quality were obtained.

In the eleventh embodiment in which the antiferroelectric liquid crystal element is driven, the number of pixels is 320 × 240.
When the panel was driven under the conditions of a holding voltage of 15 V, a writing voltage of 30 V and a writing pulse width of 150 μs, a good image was obtained. For liquid crystal materials, Chisso Corporation
"CS4000" manufactured by the company was used.

[0065]

As described above, according to the present invention, the writing pulse is divided by the dividing pulse so that the composite waveform of the information signal and the writing pulse includes the reverse polarity pulse. It is possible to prevent the switching operation of the non-existing pixels, and thereby to make the driving margin wide without increasing the voltage value of the information signal. By thus allowing a wide drive margin, the productivity of the liquid crystal element can be improved and high image quality can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a liquid crystal display circuit to which a driving method of a liquid crystal element according to the present invention is applied.

FIG. 2 is a diagram showing a structure of the liquid crystal element.

FIG. 3 is a diagram showing a scanning signal output from a scanning signal control circuit and an information signal control circuit of the liquid crystal display circuit, an information signal, and a composite waveform thereof.

FIG. 4 is a diagram showing a configuration of a scanning signal control circuit of the liquid crystal display circuit.

FIG. 5 is a diagram showing a scanning signal, an information signal and a composite waveform thereof applied to the liquid crystal element.

FIG. 6 is a diagram showing drive waveforms according to a sixth example of the present embodiment.

FIG. 7 is a diagram showing drive waveforms according to a second example of the present embodiment.

FIG. 8 is a diagram showing drive waveforms according to Example 3 of the present embodiment.

FIG. 9 is a diagram showing drive waveforms according to a fourth example of the present embodiment.

FIG. 10 is a diagram showing drive waveforms according to a fifth example of the present embodiment.

FIG. 11 is a diagram showing a scan write pulse, an information signal, and a composite waveform in a conventional liquid crystal element driving method.

FIG. 12 is a diagram showing a scanning signal, an information signal, and a composite waveform applied to a pixel in a conventional liquid crystal element driving method.

[Explanation of symbols]

 4 Scanning Signal Control Circuit 5 Information Signal Control Circuit 8 Liquid Crystal Element 9 Display Section 10 Information Signal Electrode Group 11 Scanning Signal Electrode Group 41 Writing Pulse Generating Section 42 Dividing Pulse Generating Section 43 Control Section 82 Glass Base 83 Chiral Smectic Liquid Crystal Pw Writing Pulse Ps Split pulse Pe Erase pulse Pr Reverse polarity pulse

Claims (10)

[Claims] 1. A liquid crystal is filled between a pair of substrates, and an information signal electrode group for selectively applying information signals and scanning signals to a large number of pixels forming a display screen on the substrate and scanning. In a method of driving a liquid crystal element in which a signal electrode group is formed in a matrix, a writing pulse of a scanning signal sequentially applied to the scanning signal electrode group is divided and synchronized with the scanning signal. The driving method of the liquid crystal element, wherein the composite waveform of the information signal applied to the information signal electrode group and the write pulse includes a pulse of opposite polarity. 2. A liquid crystal is filled between a pair of substrates, and the substrates are scanned with an information signal electrode group for selectively applying information signals and scanning signals to a large number of pixels forming a display screen. In a method of driving a liquid crystal element in which a signal electrode group is formed in a matrix, a scanning signal control means for sequentially applying a scanning signal having a writing pulse to the scanning signal electrode group, and the scanning An information signal control unit that applies an information signal to the information signal electrode group in synchronization with a signal, a division pulse generation unit that generates a division pulse that divides the writing pulse, and a division pulse generation that divides the writing pulse. A control means for controlling the pulse generating operation of the means, and the composite waveform with the information signal is reversed by dividing the write pulse by the dividing pulse. Method of driving a liquid crystal device characterized by including the sex pulses. 3. The method of driving a liquid crystal element according to claim 2, wherein the voltage value of the divided pulse is smaller than the voltage value of the write pulse. 4. The method of driving a liquid crystal element according to claim 2, wherein the pulse width of the divided pulse is smaller than the pulse width of the write pulse. 5. The method of driving a liquid crystal element according to claim 2, wherein the pulse width of the information signal is smaller than the pulse width of the write pulse and larger than the pulse width of the divided pulse. 6. The method of driving a liquid crystal element according to claim 2, wherein a pulse crest value of the divided pulse is smaller than a pulse crest value of the information signal. 7. The method of driving a liquid crystal element according to claim 1, wherein the liquid crystal is a chiral smectic liquid crystal which is a ferroelectric liquid crystal. 8. The method for driving a liquid crystal element according to claim 1, wherein the liquid crystal is a chiral smectic liquid crystal which is an antiferroelectric liquid crystal. 9. The method of driving a liquid crystal element according to claim 1, wherein the scan signal has an erase pulse. 10. The method of driving a liquid crystal element according to claim 1, wherein the scan signal sets the scan write pulse in a first half and a second half of a write period.