JP3423621B2 - Driving method of liquid crystal device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method of a matrix type liquid crystal device, and more particularly to a driving method of a liquid crystal device using a liquid crystal element having two stable states.

[0002]

2. Description of the Related Art Conventionally, electrodes for forming pixels in a matrix are provided on the inner surface of a liquid crystal cell, and the electrode group on one substrate is used as a scanning electrode group and the electrode group on the other substrate is used as an information electrode group. A liquid crystal display element for displaying image information by filling a liquid crystal material between these electrodes is well known. In particular,
The liquid crystal itself has spontaneous polarization, has a characteristic of responding rapidly to an electric field, and has been actively researched and developed since the 1980s, as a ferroelectric liquid crystal element capable of stably realizing two liquid crystal molecule alignment states. For example, it is proposed in JP-A-56-107216.

Various driving methods of ferroelectric liquid crystal elements proposed so far have been to write data for each scanning line. A typical driving method is shown in FIG. 16 as a conventional example. In FIG. 16, (A) shows the scanning signal waveform when selected, and (B) shows the scanning signal waveform when not selected.
(C) is an information signal waveform when writing white, and (D) is an information signal waveform when writing black. This waveform is black-erased by the V1 pulse of FIG. 16A for each line by the line-sequential writing method, and is V3 of (C) or V4 of (D).
By selecting the pulse, it is determined whether to write in white or not to write in white and maintain the black state depending on the voltage difference from the V2 pulse in (A). The voltage settings are, for example, V3 = -V4 = V5, V2 = 2 * V4, V1 = -V.
2. The pulse width is, for example, V1: V2: V5: V4
(C): V3 (d): V3 (c): V4 (d) = 5:
Set 2: 1: 1: 1: 2: 2. Concrete voltage value,
The setting of the pulse width depends on the gap between the electrodes of the cell, the temperature, and the liquid crystal material.

Since the above ferroelectric liquid crystal element has a memory property, black or white display is sufficiently retained even if the frame frequency becomes low and the time until the next writing becomes long. Therefore, it is possible to increase the screen size by increasing the number of scanning signal lines, but the deterioration of the image quality due to the decrease of the frame frequency cannot be avoided.

As a method for improving this, Japanese Patent Laid-Open No. 63-
As shown in 155032, a method of scanning a plurality of lines to realize a substantially high speed drive has been proposed. However, in the multi-line scanning described in JP-A-63-155032, the writing pulse width of each scanning signal becomes 1 / (2M) when scanning M lines, and the pulse width is proportional to the number of lines to be simultaneously scanned. Since it becomes short, it was not possible to achieve high-speed driving substantially.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to realize high-speed driving in a polar drive liquid crystal represented by a ferroelectric liquid crystal, and to increase the screen size without causing deterioration in image quality due to a decrease in frame frequency. An object is to provide a liquid crystal device that can be manufactured.

[0007]

According to the present invention, a polar drive liquid crystal having at least two stable states, intersecting scanning electrode groups and information electrode groups, and arranged in a matrix.
In the method of driving a liquid crystal device having a plurality of pixels showing two display states corresponding to the two stable states , M is 2
When the above natural numbers are set, scan selection signals having different voltage waveforms are simultaneously applied to the M scan electrodes selected from the scan electrode group during the selection period, and the information electrodes are applied to the information electrodes during the selection period. , One information signal selected from 2 ^M kinds of voltage waveforms corresponding to 2 ^M kinds of combination patterns of display states of ^M pixels at intersections of the information electrode and the M scanning electrodes. , An information signal determined in accordance with a combination pattern of the voltages of the M scanning selection signals that are simultaneously applied and a combination pattern of the display states of the M pixels. By applying the voltage, the display state of the pixels on the M scanning electrodes is determined during the selection period.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The preferred embodiment of the present invention is as follows.
Matrix driving is performed to select M scanning electrodes at the same time, and all the selection pulses of the scanning signal have a polarity for writing the pixel.

[0009]

For example, the voltage level of each phase of the information signal has a polarity in the writing direction when the voltage pattern of each phase of the scanning signals of M lines and the display pattern completely match. Has the highest voltage value V1 and has the highest voltage value V2 having the opposite polarity to the writing direction when the voltage pattern of each phase of the scanning signal does not completely match the display pattern, When the voltage pattern of each phase of the scanning signal and a part of the display pattern match, the voltage value Vn is an intermediate value between V1 and V2 according to the degree of the match.

Alternatively, the voltage value Vn of the information signal is all zero, and the voltage values V1 and V2 of the information signal are
Is characterized in that V1 = −V2.
Further, the scanning signal further includes a reset pulse. In this case, a part of the phase of the scanning signal can be configured by the reset pulse of the scanning signal.

Further, an auxiliary pulse having a polarity different from that of the write pulse may be provided immediately after the write pulse of the scan signal. The scanning electrodes selected at the same time are, for example, two or three. Or four or more also Ru possible der.

Further, as the liquid crystal, it is preferable to use a liquid crystal having a chiral smectic phase such as a ferroelectric liquid crystal or a liquid crystal having at least two stable states such as a bistable nematic liquid crystal.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The present invention, as described above, the scanning electrodes because it is by Uni configuration you select the M present simultaneously, it is possible to select the M present simultaneously at substantially the same selected time one line scanning,
Can be driven at high speed. Therefore, it may cause deterioration of image quality.
It is possible to increase the screen size. Moreover, the scanning signal if to have a reset pulse, it is possible to cancel unwanted pulse applied to the liquid crystal, it is possible to increase the driving margin. Further, the driving margin is increased by canceling unnecessary application pulse to the liquid crystal by the auxiliary pulse. In addition, if a liquid crystal having a drive characteristic most suitable for the present invention is used, the drive margin is further expanded.

The driving method of the present invention is the same as the conventional TN device or ST.
This is completely different from the driving method of the N element, and the difference will be described below.

As a driving method of a liquid crystal element, there is a voltage averaging method used for the above-mentioned TN element and STN element (“Basics of application of liquid crystal display”: Corona Company / Katsumi Yoshino,
Masanori Ozaki (page 117-130). This method controls the alignment of liquid crystals in an electric field by controlling the electric field strength applied to liquid crystal molecules by changing the effective values of selected points, semi-selected points and non-selected points. The response to the electric field in the TN element or the STN element is a so-called “cumulative response effect” in which the liquid crystal does not respond to one selection pulse but gradually responds to several selection pulses being applied. We are using. Such a writing method is possible because the driving method is based on the principle of causing the orientation change of the liquid crystal molecules so as to minimize the dielectric constant of the liquid crystal molecules in the electric field. The driving torque of the liquid crystal is proportional to the square of the electric field and does not depend on the polarity of the electric field. That is, such a state change of the liquid crystal is determined by the effective value of the applied voltage.

On the other hand, in a polarity driven liquid crystal such as a ferroelectric liquid crystal element, switching is performed by applying a voltage exceeding a liquid crystal threshold value when scanning is selected. This is an essential difference from the above-mentioned TN element and STN element. for that reason,
In the scanning signal, bipolar pulses are evenly mixed in a TN element or the like, and bipolar pulses may be present at the time of selection.
In the polarity driving liquid crystal element, the scanning signal is formed mainly by the polarity pulse in the writing direction, and the polarity pulse in the writing direction needs to exist at the time of selection.

Regarding this point, JP-A-5-10064
The same applies to the "active addressing driving method" in the STN element described in 2. This "active addressing driving method" is one of the measures for avoiding the phenomenon of the contrast reduction of the STN element.

With the speeding up of liquid crystal materials for STN elements (development of low-viscosity materials), liquid crystals have come to respond to each (effective value of) applied selection pulse. That is, when the response speed of the liquid crystal is slow, the orientation change of the liquid crystal molecules occurs over several frames depending on the effective value of the applied voltage, but the response time is 1
As soon as the frame time is reached, the liquid crystal molecules respond (change orientation) with each applied pulse. Such a phenomenon is generally called "frame response phenomenon". In this case, the difference in transmittance between on / off becomes small and the contrast is lowered.

Therefore, when the "active addressing driving method" is used, the scanning signal of several lines and the information signal are related to each other, thereby obtaining the same effect as that of increasing the frequency, suppressing the "frame response phenomenon", and improving the contrast. be able to. Therefore, the scanning time is not shortened by the "active addressing driving method", which is different from the driving method of the present invention described below.

The response to the electric field in the TN element or the STN element does not cause the liquid crystal to respond in one scanning selection period, but still utilizes the above "cumulative response effect".
On the other hand, according to the driving principle of the ferroelectric liquid crystal element, writing is completed in one scanning period, and the effective voltage value of the subsequent non-selected period is not related to the response of the ferroelectric liquid crystal element. Then, during the writing period, the switching direction of the liquid crystal is determined by whether or not the integrated value of the applied voltage including the polarity in the period exceeds the threshold value.

Next, drive waveforms used in the present invention will be described. Each phase of the scan selection signal is a combination of a phase in which a selection pulse is generated and a phase in which a selection pulse is not generated.
Simultaneous line scanning 2 ² = 4 ways, 3 lines 2 ³
= 8 ways, 4 lines can have 2 ⁴ = 16 ways of phases. FIG. 1 shows an example of scanning signals corresponding to these combinations. FIG. 1A shows a pulse waveform of 2-line scanning, and FIG. 1B shows a pulse waveform of 3-line scanning.
(C) is a matrix of scan signals for 4-line scanning. It is assumed that the selection pulse has only one polarity. In the matrix, the phase in which the selection pulse occurs is 1 and the phase in which the selection pulse does not occur is 0. Here, Vsc is a selection pulse voltage, and Vc is a reference voltage.

The information signals are considered to be 2 ² = 4 in 2 line simultaneous scanning from the display pattern, 2 ³ = 8 in 3 lines, and 2 ⁴ = 16 in 4 lines. For example, in the case of 2-line simultaneous scanning, if white display is 1 and black display is 0, (11), (00), (1
Display patterns of 0) and (01) and information signals corresponding thereto can be considered.

As shown in FIG. 2A, the voltage level of each phase of the information signal is determined in accordance with the number of coincidence of each phase of the scanning signal and the display pattern. For example, in the case of display (11), the phase (11) matches the display pattern for both two lines. The lines (10) and (01) match one line, and the phase (00) does not match two lines. Therefore,
The voltage level of the information signal is given by Vd3 having the opposite polarity to the selection pulse voltage Vsc in the phase (11), Vd2 in the phases (10) and (01), and Vd1 having the same polarity in the selection pulse voltage Vsc at (00). Here, since Vd3 has the highest degree of coincidence, it has the largest voltage value with the polarity in the writing direction, Vd1 has the lowest degree of coincidence, and therefore has the highest voltage value with the opposite polarity to Vd3, and Vd2 has the degree of coincidence. Is intermediate, so that it has a voltage value at an intermediate level between Vd1 and Vd3. Then, these voltage levels are, for example, as shown in FIG.
As shown in (a), Vd3 = -Vdl, Vd2 = Vdl
It can be / 2. Also, Vsc = 2Vd1. Since the information signal needs to be DC-compensated within a period of 1 to several H due to the driving characteristics of the ferroelectric liquid crystal element,
The phases (10) and (01) are distributed to ± Vd2.
A composite signal of these scanning signal and information signal is shown in FIG.

[0025]

Embodiments of the present invention will be described in detail below with reference to the drawings. First Embodiment First, the first embodiment will be described. 3 and 4 show driving waveforms of the liquid crystal display device used in this embodiment. Ss (N) in FIG. 3 is the address period Tn (n = 1, 2, ...
n), the scan selection signal applied to the Nth scan electrode, Ss (N + 1) is the scan selection signal applied to the N + 1th scan electrode, and Sn is the scan non-selection signal applied to the unaddressed scan electrode. Is represented.

On the other hand, I (WW), I (BB), I (B
W) and I (WB) are information signals that are selectively applied to the signal electrode group, and two lines correspond to signals that display white and white, black and black, black and white, and black and white, respectively. That is, in the address period Tn, one of the four information signals is applied depending on the display state. The scanning signal voltage Vsc = Vs and the information signal voltage are Vd1 = Vs and Vd2 = Vs / 2.

FIG. 4 is a time-series representation of the voltage waveform when the drive voltage of FIG. 3 is applied, and the display of the intersections (pixels) of the scan electrodes S1 to S4 and the signal electrode Ia shown in FIG. It is based on state. According to FIG. 4, the first scan electrode S1 and the second scan electrode S2 in the address period T1.
Are simultaneously addressed to scan electrodes S1 and S2 respectively.
The scan signals Ss (N) and Ss (N + 1) shown in FIG. 3 are applied, the third scan electrode S3 and the fourth scan electrode S4 are simultaneously addressed in the address period T2, and the scan electrodes S3 and S4 are respectively shown in FIG. Scan signals Ss (N) and Ss (N +
1) is applied. Before each address period Tn, an erase pulse in the previous state having a pulse width of Tn-1 period and a pulse voltage of 2Vs (black display is the erase direction) is applied.

In the present embodiment, the pixels on the scan electrodes S1 and S2 that intersect the signal electrode Ia are in the white display state, so that the information signal I (WW) is applied during the address period T1 and the scan electrodes S3 and S4 are applied. Since each of the pixels is in the black display state, the information signal I (BB) is generated in the address period T2.
Is applied.

As a result, the composite waveform of S1-Ia, S2-Ia, S3-Ia and S4-Ia shown in FIG. 4 is applied to each intersection. As a result, during the selection period of the scan electrode S1 for displaying white, the phase t2 is 2 Vs and the phase t
Vs / 2 is applied at 3 and t4, and 2Vs at phase t2 and -Vs / 2, t at phase t3 during the selection period of the scan electrode S2.
At 4, 1.5 Vs is applied. Further, during the selection period of the scan electrode S3 for displaying black, Vs at phase tl and phase t3
Is applied at −1.5Vs, and −Vs / 2 is applied at phase t4. During the selection period of the scan electrode S4, Vs at phase tl, phase t3,
Vs / 2 is applied at t4. That is, in the white display selection period (T1), assuming that the time widths of t1, t2, t3, and t4 are 1, the polarity direction of the white display is positive, and the polarity from the erase period is phase-inverted, and then the integrated value is obtained. 2Vs + Vs /
2 + Vs / 2 (or 2Vs-Vs / 2 + 1.5V
s) pulse is applied, Vs + during the black display selection period
1.5Vs-Vs / 2 (or Vs + Vs / 2 + Vs
/ 2) pulse is applied. Therefore, the threshold voltage Vth of the liquid crystal is

[0030]

[Equation 2] If so, black and white can be separately written within the selection period Tn.

FIG. 6 shows the application time dependency of the threshold voltage of the liquid crystal used in this example. In the figure, the writable area is a range in which white can be written after black erasing, and the unwritable area is a range in which white cannot be written after black erasing and a black state is maintained. In the present specification, the threshold is the voltage
It is defined as a function (combination) of and application time.
For example, in the curve of FIG. 6, the voltage should be a constant.
Value is defined by the application time, and if the application time is a constant,
The threshold value is defined by voltage. Normally, in a liquid crystal exhibiting a chiral smectic phase such as a ferroelectric liquid crystal, the product of the applied voltage and the voltage application time is constant with respect to the threshold value. However, in the present liquid crystal, the applied voltage has a stronger influence on the threshold value than the applied time, and even if the product of the applied voltage and the applied time is the same, the larger the applied voltage is, the lower the threshold value is. This facilitates the design of the drive waveform for writing the white and black states depending on the magnitude of the applied voltage during the selection period, and is suitable when the voltage values are different between the voltage white writing and the black writing as in the present embodiment. There is. When the boundary between the writable area and the unwritable area shown in FIG. 6 is expressed by an equation, the applied voltage is V, the application time is Δt, and
The first threshold is V1, Δt1, and the second threshold is V
2 and Δt2,

[0032]

[Equation 3] Becomes Note that Vs can be set to 1 to 30 V and each phase tl to t4 can be set to 1 to 50 μs.

Further, in this embodiment, the scanning signal voltage Vsc,
Although the information signal voltage Vd is Vsc = Vd = Vs,
c = 2Vd, Vsc = 3Vd, etc., and preferably V
It is set within the range of d ≦ Vsc ≦ 3Vd.

FIG. 7 shows the panel structure of the liquid crystal display device used in this embodiment. In FIG. 7, 110 is a liquid crystal display panel, 100 is a pixel for displaying an image in each area, 101 is a scan electrode driver that selects each scan electrode 102 and outputs a drive waveform to the selected scan electrode 102 at a predetermined timing, 103 is a liquid crystal display panel 11 according to a video input signal.
0 is an information electrode driver that outputs a predetermined drive waveform to the information electrode 104 at a predetermined timing. As shown in FIG. 7, each pixel is configured in a matrix type, information of each pixel is supplied from an information signal electrode, and a scanning signal of each line is supplied from a scanning signal electrode for driving.

FIG. 8 shows a block circuit diagram of the liquid crystal display device used in this embodiment. In FIG. 8, 110 is a liquid crystal display panel for displaying an image, 101 is a scan electrode driver, 1
Reference numeral 03 is an information electrode driver, 4 is a drive control circuit having a scanning signal control circuit 5 and an information signal control circuit 6, 7 is a drive voltage generation circuit, and 8 is a video RAM (V) for storing image information.
RAM) 9 is a graphic controller.

Data is transferred from the graphic controller 8 having the VRAM 9 to the drive control circuit 4 according to the transfer clock. This data is input to the scanning signal control circuit 5 and the information signal circuit 6 and converted into address data and display data, respectively. According to this address data,
The scan electrode driver 101 and the information electrode driver 103 output the scan signal waveform and the information signal waveform. Each drive voltage level is generated by the drive voltage generation circuit 7.

In this embodiment, as the liquid crystal cell, a cell having a structure in which the surface of the counter substrate is different as shown in FIG. 9 was used. In the figure, 701 and 707 are glass substrates and 702 and 7
Reference numeral 06 is a transparent electrode such as ITO, 703 is an alignment film having a horizontal alignment function subjected to uniaxial alignment treatment such as rubbing treatment,
Reference numeral 704 is a ferroelectric liquid crystal layer, and 705 is a vertical alignment treatment material. 708, 709 and 710 are front views of the cone that characterizes the liquid crystal molecules in the chiral smectic layer, and in this example, 708 and 709 formed two stable states in the uniform orientation. Note that reference numeral 710 indicates an example of a splay alignment state formed in a minute region.

A specific example of the procedure for producing a liquid crystal cell will be described below. First, a pair of glass substrates on which an ITO film having a thickness of 70 nm was formed by a sputtering method as transparent electrodes were prepared.
On one ITO film, a NMP (N-methylpyridone): n-BC (n-butyl cellosolve) mixed solution of polyamic acid LP-64 (manufactured by Toray Industries, Inc.), which is a polyimide precursor, was spin-coated. That is, the coating solution is NMP: n-B
LP-64 was prepared in a mixed solvent of C = 2: 1 so as to be 1% by weight, and the coating was carried out at a spin condition of 45 rpm for 20 seconds. This substrate was subjected to solvent drying in an oven at 80 ° C. for 5 minutes and then heated and baked in an oven at 200 ° C. for 1 hour to imidize. The obtained polyimide film had a thickness of about 10 nm and was rubbed to form an alignment film. For rubbing, a nylon film wound around a roller with a diameter of 10 cm was used, 16.7 rotations / second, the pushing of the cloth against the surface of the alignment film was 0.4 mm, and the substrate feed rate was 1
Rubbing was performed twice (one way) in the same direction at 0 mm / sec. Then, an IPA in which silica beads having an average particle size of 2.0 μm are dispersed at 0.008% by weight on the surface of the substrate
(Isopropyl alcohol) solution, 25 revolutions / second, 1
Spin coating under 0 second condition, dispersion density 300 / mm ²
Some bead spacers were sprinkled. The other substrate on the opposite side is a silane coupling agent (O
45% of a 0.5 wt% ethyl alcohol solution of DS-E)
Spin coating was performed under the conditions of rotation / second and 20 seconds, and vertical alignment treatment was performed. Then, a thermosetting sealant was applied onto this substrate by printing. The two substrates thus obtained were laminated facing each other and thermally cured in an oven at 150 ° C. for 90 minutes to obtain a cell (empty cell). Subsequently, a liquid crystal material exhibiting a chiral smectic layer was injected into the empty cell at a temperature showing an isotropic phase, and was gradually cooled to the temperature of the chiral smectic phase. The liquid crystal has a spontaneous polarization of 30n at 25 ° C.
A material having characteristics of C / cm ² , a layer inclination angle δ at 20 ° C. of 0 °, and a tilt angle of 22 ° was used.

Next, the device obtained as described above is shown in FIG.
The driving characteristics were evaluated by displaying the entire white and the entire black with the driving waveform as shown in FIG. The results are shown in Table 1. As a comparative example, the result when the same element is driven by the drive waveform of FIG. 16 described in the conventional example is shown. In the drive waveform shown in FIG. 4, Vs = 8V and Vc = 0V, and in the drive waveform shown in FIG. 16, V1 = 14V, V2 = -14V,
V3 = 6V, V4 = -6V, V5 = 7V. The number of pixels in the liquid crystal element was 320 × 240.

[0040]

[Table 1]

The drive margin is represented by drive margin = (value causing crosstalk-threshold value) / (value causing crosstalk + threshold value) at a constant voltage. In this embodiment, since the present embodiment drives two lines simultaneously, the threshold value of one line / 2 is used. As described above, in the present embodiment, the driving margin was slightly lowered, but the threshold value was almost halved, and high-speed driving was possible.

Second Embodiment Next, a second embodiment will be described. The present embodiment is different from the first embodiment in the form of the information signal. 10 and 11 show drive waveforms of the liquid crystal display device used in this embodiment. Figure 1
Ss (N) of 0 is the address period Tn (n = 1,
2 ,. ． ． ． , N), a scan selection signal applied to the Nth scan electrode addressed, Ss (N + 1) is a scan selection signal applied to the N + 1th scan electrode, and Sn is a scan non-selection applied to an unaddressed scan electrode. Represents a signal.

On the other hand, I (WW), I (BB), I (B
W) and I (WB) are information signals that are selectively applied to the signal electrode group, and two lines correspond to signals that display white and white, black and black, black and white, and black and white, respectively. The scanning signal voltage is Vsc = Vs, and the information signal voltage is Vsc, which is different from the first embodiment.
Let d1 = Vd = Vs and Vd2 = Vc.

FIG. 11 is a time-series representation of the voltage waveforms when the drive voltage of FIG. 10 is applied. The display of the intersections (pixels) of the scan electrodes S1 to S4 and the signal electrode Ia shown in FIG. It is based on state. According to FIG. 11, the first scan electrode S1 and the second scan electrode S2 are simultaneously addressed in the address period T1, and the scan signals Ss (N) and Ss (N + 1) shown in FIG. 10 are supplied to the scan electrodes S1 and S2, respectively. Is applied, the third scan electrode S3 and the fourth scan electrode S4 are simultaneously addressed in the address period T2, and the scan signals Ss (N) and S shown in FIG. 10 are applied to the scan electrodes S3 and S4, respectively.
s (N + 1) is applied. Each address period T
Before n, an erase pulse having a pulse width of Tn-1 period and a pulse voltage of 2Vs is applied.

In the present embodiment, the pixels on the scan electrodes S1 and S2 that intersect the signal electrode Ia are in the white display state, so that the information signal I (WW) is applied during the address period T1 and the scan electrodes S3 and S4 are applied. Since each of the pixels is in the black display state, the information signal I (BB) is generated in the address period T2.
Is applied.

As a result, S1-Ia, S2-Ia, S3-Ia and S4-Ia shown in FIG. 11 are provided at the respective intersections.
Is applied. As a result, in the selection period of the scan electrode S1 that performs white display, 2 Vs is applied at the phase t2 and Vs is applied at the phase t3, and during the selection period of the scan electrode S2,
2Vs is applied at phase t2 and Vs is applied at phase t4. Further, during the selection period of the scan electrode S3 for displaying black, Vs is applied at the phase tl and Vs is applied at the phase t3, and the scan electrode S4 is applied.
In the selection period of, Vs is applied at phase tl and Vs is applied at phase t4. In other words, during the white display selection period, the integrated value is 2
Vs + Vs is applied, and Vs + V is applied during the black display selection period.
s is applied, the threshold voltage Vth of the liquid crystal is

[0047]

[Equation 4] If so, it is possible to write in black and white within the selection period. Note that Vs can be set to 1 to 30 V and each phase tl to t4 can be set to 1 to 50 μs. Further, in the present embodiment, the scanning signal voltage Vsc and the information signal voltage Vd are V
sc = Vd = Vs, but Vsc = 2Vd, Vsc =
It may be 3Vd or the like, and is preferably set in the range of Vd ≦ Vsc ≦ 3Vd. The panel structure and the block circuit diagram of the liquid crystal display device used in this embodiment are the same as those in the first embodiment, and the description thereof will be omitted.

FIG. 1 shows a concrete example of this embodiment.
Using the drive waveforms 0 and 11, Vs = 10V, Vc =
A device other than that was set to 0 V, and the other devices and the like were configured in the same manner as in the above-mentioned embodiment, and the driving characteristics in the case of full-white display and full-black display were evaluated. The results are shown in Table 2. As a comparative example, the result of the drive waveform of FIG. 16 described in the conventional example is shown. As described above, the driving margin of the present embodiment was slightly higher than that of the first embodiment, and the threshold value was almost halved, enabling high speed driving.

[0049]

[Table 2]

Third Embodiment Next, a third embodiment will be described. In the third embodiment, an erase pulse is devised in comparison with the second embodiment, and an auxiliary pulse is added to use a drive waveform for increasing the drive margin. The panel structure and the block circuit diagram of the liquid crystal display device used in this embodiment are the same as those in the first embodiment, and the description thereof will be omitted.

FIG. 12 shows the voltage waveform of the third embodiment in time series, which is based on the display state at the intersections (pixels) of the scan electrodes S1 to S4 and the signal electrode Ia shown in FIG. Is. According to FIG. 12, the first scan electrode S1 and the second scan electrode S2 are simultaneously addressed in the address period T1, and the third scan electrode S3 and the fourth scan electrode S4 are simultaneously addressed in the address period T2. . 12
As can be seen from the waveforms of S1 and S2, the scanning signal is the erase pulse up to the phase tl within the address period, and the auxiliary pulse is immediately after the writing pulse (the phase t4 at the scanning electrode S (N)) in the second embodiment. , The scan electrode S (N + 1) is inserted in the phase t1 of the next address period. A voltage waveform similar to that in the second embodiment is applied to the information signal. The voltage of the auxiliary pulse Vh is set to Vh = Vs.

In this embodiment, since the pixels on the scan electrodes S1 to S4 are in the black display state, the address periods T1 and T2 are set.
Then, the information signal I (BB) is applied to each. The synthesized waveforms are S1-Ia, S2-Ia, S3-I shown in FIG.
a, S4-Ia.

According to such a drive waveform, Vs at the phase t3 during the selection period of the scan electrode S1 for displaying black is
During the selection period of the scan electrode S2, only Vs is applied at the phase t4. That is, the phase t
Since Vs of 1 is not applied and the influence of the information signal in the next address period is reduced by the auxiliary pulse, black display is advantageous and the driving margin is widened.

Next, as a concrete example of this embodiment, using the drive waveforms shown in FIGS. 10 and 11, Vs = 10V, Vc =
With respect to the conditions of the other devices such as 0 V, the driving characteristics when the entire white display and the entire black display were performed were evaluated as in the case of the first embodiment. The results are shown in Table 3. As a comparative example, the result of the drive waveform of FIG. 16 described in the conventional example is shown. In this way, by devising the erase pulse, auxiliary pulse, etc.,
A larger drive margin can be secured.

[0055]

[Table 3]

Fourth Embodiment Next, a fourth embodiment will be described. The fourth embodiment is 3
It uses a drive waveform that drives the lines at the same time.
The panel structure and the block circuit diagram of the liquid crystal display device used in this embodiment are the same as those in the first embodiment, and the description thereof will be omitted.

FIG. 14 is a time-series representation of the voltage waveform of this embodiment, which is based on the display state at the intersections (pixels) of the scan electrodes S1 to S6 and the signal electrode Ia shown in FIG. . According to FIG. 14, the scan electrodes S1 to S3 are simultaneously addressed in the address period T1, and the scan electrodes S4 to S6 are simultaneously addressed in the address period T2. The selection pulse voltage Vsc = Vs of the scanning signal and the information signal voltage are Vd1 = -Vd4 = Vs and Vd2 = Vd3 = Vc.

In this embodiment, the pixels on the scan electrodes S1 to S3 intersecting the signal electrodes Ia are in the white display state, so that the information signal for displaying the white is applied in the address period T1 and the scan electrodes S4 to S6 are applied. Since each of the pixels is in a black display state, an information signal for displaying black is applied during the address period T2. The combined waveforms are S1-Ia and S2- in FIG.
Ia, S3-Ia, S4-Ia, S5-Ia, S6-I
a. As a specific example of this embodiment, the drive waveforms shown in FIG. 14 are used, and Vs = 8V and Vc = 0V. Other conditions such as devices are when all white and all black are displayed as in the first embodiment. Table 4 shows the drive characteristics of the. As a comparative example, the result of the drive waveform of FIG. 16 described in the conventional example is shown.

[0059]

[Table 4]

[0060]

As for the threshold value, since the present embodiment drives three lines simultaneously, the threshold value / three for one line is set to the threshold value / 3.
As described above, in the three-line simultaneous driving, although the driving margin is reduced, the threshold value becomes almost ⅓, and high-speed driving becomes possible.

As described above, according to the present invention, M waveforms are simultaneously selected in a selection time substantially similar to one line scanning by using a driving waveform suitable for driving a plurality of lines, so that high speed driving and image quality are possible. It is possible to increase the screen size without lowering the display. Further, by effectively utilizing the reset pulse, the unnecessary applied pulse can be canceled, so that the driving margin can be increased.
Further, by applying the auxiliary pulse after the write pulse, the write pulse at the time of half-selection can be reduced, so that the drive margin can be increased.

Further, by using the liquid crystal having the optimum driving characteristic in the present invention, the driving margin can be further increased.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of a scanning signal having a drive waveform according to the present invention.

FIG. 2 is a diagram illustrating an example of a drive waveform information signal and a composite signal of the present invention.

FIG. 3 is a diagram illustrating drive waveforms of the first embodiment of the liquid crystal device according to the present invention.

FIG. 4 is a diagram showing drive waveforms of a first embodiment of the liquid crystal device according to the present invention in time series.

FIG. 5 is a diagram illustrating a driving state of a pixel unit according to the first embodiment.

FIG. 6 is a diagram showing an example of driving characteristics of liquid crystals used in the liquid crystal device according to the first embodiment of the invention.

FIG. 7 is a diagram illustrating a panel configuration of the liquid crystal device according to the first embodiment of the invention.

FIG. 8 is a diagram illustrating a block circuit of the liquid crystal device according to the first embodiment of the invention.

FIG. 9 is a diagram illustrating a liquid crystal cell configuration of the liquid crystal device according to the first embodiment of the invention.

FIG. 10 is a diagram illustrating drive waveforms according to the second embodiment of the present invention.

FIG. 11 is a diagram illustrating drive waveforms according to the second embodiment of the present invention.

FIG. 12 is a diagram illustrating drive waveforms according to the third embodiment of the present invention.

FIG. 13 is a diagram illustrating a driving state of a pixel portion according to a third embodiment of the present invention.

FIG. 14 is a diagram illustrating drive waveforms according to a fourth embodiment of the present invention.

FIG. 15 is a diagram illustrating a driving state of a pixel portion according to a fourth embodiment of the present invention.

FIG. 16 is a diagram showing drive waveforms of a liquid crystal device of a conventional example.

[Explanation of symbols]

1: liquid crystal display panel, 4: drive control circuit, 5: scanning signal control circuit, 6: information signal control circuit, 7: drive voltage generation circuit, 8: graphic controller, 9: VRAM, 1
00: pixel, 101: scan electrode driver, 102: scan electrode, 103: information electrode driver, 104: information electrode,
110: Liquid crystal display panel.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-68696 (JP, A) JP-A-6-27904 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/133 560 G02F 1/133 545 G09G 3/36

Claims (6)

(57) [Claims] 1. A polar driving liquid crystal having at least two stable states, a scanning electrode group and an information electrode group intersecting each other, and arranged in a matrix to correspond to the two stable states.
In the method for driving a liquid crystal device having a plurality of pixels showing two display states , when M is a natural number of 2 or more, M scan electrodes selected from the scan electrode group are simultaneously applied to M scan electrodes in the selection period. While applying scan selection signals having different voltage waveforms, the display state of M pixels at the intersection of the information electrode and the M scan electrodes is applied to the information electrode during the selection period .
Be one of the information signal selected from 2 ^M Street voltage waveform corresponding to the combination pattern of 2 ^M Street, voltage at each phase of the information signal, M-number of the voltage of the scanning selection signal applied simultaneously By applying an information signal determined according to the combination pattern of M and the combination pattern of the display states of the M pixels, the display state of the pixels on the M scan electrodes is determined during the selection period. A method for driving a liquid crystal device, comprising: 2. The method of driving a liquid crystal device according to claim 1, wherein the scan signal has a reset pulse.
Law . Wherein the scanning signal driving method of a liquid crystal device according to claim 1 or 2, characterized wherein said selected pulse and polarity immediately after the selection pulses have a different auxiliary pulse. Wherein said voltage of said each phase of the information signal
Is a combination of the voltages of the respective phases of the scanning signals of M lines.
In the case where the combination pattern and the combination pattern of the display states of the M pixels are completely coincident with each other, it has the highest voltage value V1 having the polarity in the writing direction, and the scanning signals for M lines are the same. Combination of the above voltages for each phase
If the combination <br/> pattern display state of the the Align pattern M pixels do not match exactly, it has the highest voltage value V2 with writing direction opposite polarity, of the scanning signal of M duty Combination of the voltage of each phase
If some combination <br/> pattern display state of the the Align pattern M pixel match, and characterized by having an intermediate voltage value Vn of the V1 in accordance with the degree of match V2 the liquid crystal device according to any one of claims 1 to 3 for
Driving method . 5. The voltage values Vn of the information signal are all zero and the relationship between the voltage values V1 and V2 of the information signal is
The method for driving a liquid crystal device according to claim 4 , wherein V 1 = −V 2. 6. A method for driving a liquid crystal device according to any one of claims 1 to 5, wherein the liquid crystal is characterized in that it is a liquid crystal exhibiting a chiral smectic phase.