JPH11202298A - Riving method for liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving method for liquid crystal display element which can display in uniform density by excluding the influence of crosstalk. SOLUTION: A display state is switched by impressing pulse voltages through scanning electrodes 131 -13N and signal electrodes 141 -14M arranged in the shape of a matrix on liquid crystal having memory property. The lowering amount of density caused by the crosstalk of a voltage impressed continuously to the impression of a voltage corresponding to the prescribed density to each pixel is previously calculated and a voltage corrected by that lowering amount is impressed to each pixel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a liquid crystal display element, and more particularly, to a method for driving a liquid crystal display element by sandwiching liquid crystal between two substrates provided with electrodes on the surface and changing the state of the liquid crystal by a voltage applied to the electrodes. In particular, the present invention relates to a method for driving a matrix-driven bistable liquid crystal display element using a liquid crystal exhibiting a cholesteric phase.

[0002]

2. Description of the Related Art In a liquid crystal display element in which a composite film of a liquid crystal exhibiting a cholesteric phase such as cholesteric liquid crystal or chiral nematic liquid crystal and a resin material is sandwiched between two substrates, a high voltage is applied between electrodes provided in the substrates. It is known that when a pulse is applied, the liquid crystal enters a planar state, and when a low voltage pulse is applied, the liquid crystal enters a focal conic state. Then, each state is maintained for a long time without applying an electric field from the outside.

Assuming that the helical pitch in the planar state is P and the average refractive index of the liquid crystal is N, the wavelength λ = P ·
N lights are selectively reflected. In the focal conic state, light is almost transparent to the extent that it is weakly scattered. There has been proposed a liquid crystal display element in which a member that absorbs visible light is provided on the back surface of a substrate, and a reflective display is performed by switching between a selective reflection state and a transmission state by utilizing the above-described characteristics.

In such a liquid crystal display device, when the selective reflection wavelength of the liquid crystal is set in the infrared light range, only the infrared light having the selective reflection wavelength is reflected and the visible light is transmitted in the planar state. In the focal conic state, visible light is scattered and hardly transmitted. Therefore, black and white display can be performed using this characteristic.

In a twisted nematic liquid crystal, a super twisted nematic liquid crystal or the like, the state of the liquid crystal changes according to the effective value of the driving voltage. Therefore, when the number of pixels increases, the display contrast cannot be sufficiently obtained by simple matrix driving. However, a liquid crystal exhibiting a cholesteric phase has a memory property in a display state as described above, and thus can drive a large number of pixels by simple matrix driving. The driving by a simple matrix is disclosed in US Pat. No. 5,251,048.

[0006]

SUMMARY OF THE INVENTION U.S. Pat.
The simple matrix driving method disclosed in the specification No. 48 includes a plurality of scanning electrodes and signal (segment) electrodes,
A scan electrode to be written is selected by applying a voltage to only one of the scan electrodes, a voltage corresponding to the data to be displayed is applied to the signal electrode, and the difference between the voltage of the scan electrode and the voltage of the signal electrode is applied to the planar electrode. An image is written as a state or a focal conic state. At this time, in order to bring the liquid crystal into the planar state, a voltage that is different from the voltage of the scanning electrode is applied to the signal electrode and is sufficient to bring the liquid crystal into the planar state. Further, in order to bring the liquid crystal into the focal conic state, a voltage having a difference from the voltage of the scanning electrode lower than the voltage for bringing the liquid crystal into the planar state is applied to the signal electrode. However, in any case, the voltage applied to the signal electrode must be sufficiently low so as not to disturb the state of the liquid crystal of another pixel already written. In the present specification, the influence of the signal voltage on the pixel once written is hereinafter referred to as crosstalk.

However, even if it is intended to set a sufficiently low voltage as the signal electrode voltage, in a display element having a large number of pixels,
The effect of crosstalk due to signal electrode voltage cannot be ignored,
A density difference occurs between a pixel at the beginning of scanning of the display panel and a pixel at the end of scanning. That is, in such a liquid crystal display element, since the display memory property is used, after the writing operation is performed once, the next writing is not performed until the display data changes. Thus, the pixels corresponding to the first scan line of the display element are affected by the crosstalk of many pixels written thereafter, while the pixels corresponding to the last scan line are written later. Since the number of pixels is small, the amount of crosstalk is small. For example, assuming that the planar state is written to all the pixels of the display element, the pixel of the first scan line, after the planar state is written, all the signal electrode voltages applied when writing the subsequent scan lines cause crosstalk. . However, the pixels on the last scan line have no crosstalk since no voltage is applied after the data is written until the next scan is started.

It is an object of the present invention to provide a method of driving a liquid crystal display element capable of eliminating the influence of crosstalk and displaying an image at a uniform density.

[0009]

In order to achieve the above object, the present invention provides a method of driving a liquid crystal display element which switches a display state by applying a pulse voltage to a liquid crystal exhibiting a memory property through a matrix electrode. After the voltage corresponding to the predetermined density is applied to the pixel, the amount of reduction in density due to crosstalk of the voltage subsequently applied is calculated in advance, and a voltage corrected for the amount of reduction is applied to each pixel.

[0010]

In the present invention, the amount of crosstalk received by each pixel is calculated in advance from display data, and
The signal electrode voltage in which the amount of crosstalk is corrected is calculated, and the liquid crystal is driven so that the display state after receiving the crosstalk becomes uniform.

That is, according to the present invention, as a signal electrode voltage for writing to each pixel, a voltage in which the amount of crosstalk applied subsequently to each pixel after application of the display voltage is corrected in advance. Since the driving is performed using such a method, uniform display without image deterioration due to crosstalk can be performed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the method for driving a liquid crystal display device according to the present invention will be described with reference to the accompanying drawings.

(Configuration of Liquid Crystal Display Element) FIG. 1 shows a liquid crystal display element 10 to which the present invention is applied, and FIG. 2 shows a driving circuit thereof. As shown in FIG. 2, the liquid crystal display element 10
It is configured as a simple matrix drive display panel having M × N pixels composed of M columns and N rows.

Reference numerals 11 and 12 denote film substrates made of polycarbonate having a thickness of 120 μm.
TO (Indium Tin Oxide) transparent electrodes 13 and 14 are deposited in a predetermined pattern. The electrode 13 is a scanning electrode, and the electrode 14 is a signal electrode. Reference numeral 15 denotes a resin spacer having a diameter of 10 μm. 16 is a resin and 17 is a liquid crystal droplet, both of which form a liquid crystal / resin composite film 18. 1
9 is a visible light absorbing layer of black paint.

As a liquid crystal material, a nematic liquid crystal MN is used.
In order to make 1000XX (manufactured by Chisso) exhibit a cholesteric phase at room temperature, a material containing 43 wt% of a chiral dopant S-811 (manufactured by Merck) is used. As a resin material, a photopolymerization initiator DAROCUR 1173
A bifunctional acrylate R712 (manufactured by Nippon Kayaku) to which 3 wt% (manufactured by Ciba Geigy) is added is used. The liquid crystal material and the resin material were mixed at a weight ratio of 80:20. The liquid crystal / resin composite film 18 is obtained by mixing a liquid crystal material and a resin material well, then dropping the liquid crystal material and the resin material onto the substrate 12 coated with the spacer 15, covering the substrate 11 from above and bringing it into close contact, and then irradiating the resin material with ultraviolet rays. Is polymerized.

(Drive Voltage) FIG. 3 shows a basic drive waveform used in the present embodiment, in which the horizontal axis represents time and the vertical axis represents voltage. The pulse voltage 80 is referred to as an initialization pulse, and 8
1 and 82 are respectively referred to as a first write pulse and a second write pulse, and both are collectively referred to as a write pulse. The voltage Vth of the initialization pulse 80 is a voltage sufficient to bring the liquid crystal into a homeotropic state. When an initializing pulse 80 is applied to a certain pixel of the liquid crystal display element 10, the liquid crystal enters a homeotropic state at a high voltage portion. Changing towards. When the write pulses 81 and 82 are applied before the state has completely settled down to the planar state, depending on the magnitude of the pulse voltage, the state becomes stable in the planar state when the voltage is large and in the focal conic state when the voltage is small. . In the planar state, the liquid crystal selectively reflects light of a specific wavelength, and in the focal conic state, the liquid crystal is in a transmission state and exhibits a low reflectance.

FIG. 4 shows the relationship between the driving voltage and the reflectance when a pixel of the liquid crystal display element 10 is driven with the waveform shown in FIG. The horizontal axis represents the write pulse voltage and the voltages of the write pulses 81 and 82, and the vertical axis represents the write pulse 8
The reflectance of the liquid crystal after applying 1,82 is shown. When the write pulse voltage is Vth, the reflectivity reaches the maximum value at T1, and the reflectivity is saturated even if the voltage is further increased. When the write pulse voltage is Vfc, the reflectance becomes lowest at T2. By setting the write pulse voltage to a value between Vth and Vfc, the reflectance can be set to any value between T1 and T2.

FIG. 5 shows voltage waveforms applied to the electrodes 13 and 14 and the liquid crystal. In FIG. 5, the scanning electrode voltage indicates a voltage waveform applied to a certain scanning electrode 13. The signal electrode voltage indicates a voltage applied to a certain signal electrode 14. The liquid crystal voltage is a voltage applied to the liquid crystal, and a voltage of a difference between the scanning electrode voltage and the signal electrode voltage is applied. The scanning electrode voltage is a pulse voltage of the voltage Vth, and is applied to only one of the N scanning electrodes 13 corresponding to a pixel to be written. The signal electrode voltage is a pulse voltage synchronized with the second and third pulses of the scan electrode voltage, and the voltage Vc ranges from 0 to Vth-Vfc according to the reflectance of the liquid crystal to be written. Accordingly, a pulse voltage of Vth is applied to the liquid crystal as an initialization pulse and a pulse voltage of Vw is applied to a liquid crystal as a write voltage, as shown in the lowermost row of FIG. Here, the pulse voltage Vw takes a value between Vth and Vfc.

In the driving circuit shown in FIG. 2, only the electrode portion of the liquid crystal display element 10 is shown for explanation. The liquid crystal display element 10 is configured as a liquid crystal panel having N pixels vertically and M pixels horizontally, a total of N × M pixels. The electrodes 13 ₁ , 13 ₂ , ...,
13 _j, ... 13 _N scanning electrodes, 14 _1, 14 _2, ..., 1
3 _i, ..., 14 _M are signal electrodes.

An image data memory 57 stores image display data to be displayed on the liquid crystal display element 10 as 8-bit data per pixel. Image data memory 5
The method of writing data to 7 is well known, and a description thereof will be omitted. For example, when the present liquid crystal display element 10 is used as a display device of a computer, the image data memory 57 corresponds to a VRAM of the computer.

Reference numeral 58 denotes a drive circuit control unit which performs data conversion from display data of the image data memory 57 to data of the signal electrode drive circuit 66 and controls the scan electrode drive circuit 65 and the signal electrode drive circuit 66. 75 is a display data correction unit,
The crosstalk is corrected, that is, the amount of the crosstalk is calculated in advance based on the display data in the image data memory 57, and the corrected display data is created.

Reference numeral 76 denotes a bus which stores an image data memory 57 and a drive.
Display data between the motion circuit control unit 58 and the data correction unit 75
And a control signal and the like to the control unit 58 are sent. 59 is
The signal line is used to drive the scan electrode drive circuit 6 from the drive circuit control unit 58.
The scan electrode data is sent to 5. 60 sends a strobe signal
61 is a signal line for sending a clock.
is there. Signal line 67₁, 67_Two, ..., 67_j, ..., 67_NIs
Scanning electrode 13 ₁, 13_Two, ..., 13_j, ..., 13_N
And a signal line for supplying a scan electrode voltage to the scan line.

The scan electrode drive circuit 65 is provided with a shift register 6
5a and a driver 65b. The scan electrode shift register 65a is configured in N stages of 1 bit, and shifts data transferred from the signal line 59 in synchronization with a clock transferred from the signal line 61. The scan electrode driver 65b converts the data in the shift register 65a into the voltage Vth in synchronization with the strobe signal transferred from the signal line 60.
And level conversion, the signal lines _{67 1, 67 2, ...,} 67 j, 6
7 Output to _N.

A signal line 64 sends signal electrode data from the drive circuit control section 58 to the signal electrode drive circuit 66. 63 is a signal line for transmitting a strobe signal, and 62 is a signal line for transmitting a clock. Signal lines 68 _1, 68 _2, ..., 6
8 _i, ..., 68 _M are each the signal electrodes 14 _1, 14 _2,
, 14 _i ,..., 14 _M are signal lines for supplying signal electrode voltages.

The signal electrode drive circuit 66 includes the shift register 6
6a and a driver 66b. The signal electrode shift register 66a is configured in 8 bits and M stages, and shifts data transferred from the signal line 62 in synchronization with a clock transferred from the signal line 64. The signal electrode driver 66b changes the level of the data of the shift register 66a from the voltage 0 (V) to the range of Vth-Vfc (V) according to the data in synchronization with the strobe signal transferred from the signal line 63, and Lines 68 ₁ , 68 ₂ ,..., 68 _{i ,.}
Output to

(Driving Operation) FIG. 6 shows a scanning electrode driving circuit 65.
3 shows the signal waveforms of FIG. In FIG. 6, data, clock, and strobe are signals sent from the drive circuit control unit 58 through signal lines 59, 61, and 60, respectively. The scanning electrode outputs ₁ , ₂ , ₃ , 4 are signal lines 67 ₁ , 67 ₂ , 67 ₃ , 67 ₄
Is the voltage output to Data sent from the drive circuit control unit 58 through the signal line 59 is stored in the shift register 65.
a is shifted and sent to the scanning electrodes 13 in order in synchronization with the strobe signal. Scan electrode outputs 1, 2,
Are level-shifted to Vth by the driver 65b.

FIG. 7 shows a signal waveform of the signal electrode drive circuit 66. FIG. 7 shows a waveform near the timing when the scanning electrodes 13 _j and 13 _{j + 1} are selected, and the timing of the scanning electrodes 13 _j and 13 _{j + 1} is clearly shown so that the timing with the voltage waveform of the signal electrode 14 can be easily understood. Voltage waveforms are also shown for reference.

In FIG. 7, data, clock, and strobe are signals sent from the drive circuit control unit 58 through signal lines 62, 64, and 63, respectively. Signal electrode output i is the voltage outputted to the signal line 68 _i. The data sent from the drive circuit control unit 58 via the signal line 62 is shifted through the shift register 66a and sent to the signal electrode 14 in synchronization with the strobe signal. Drive circuit control unit 5
8 is 8-bit data per pixel, the data amount is M × 8 bits per scan of the signal electrode 14, and the number of clock pulses for shifting the data is M × 8. It is individual. The voltage of the signal electrode output i is changed from 0 (V) to Vth-Vfc (V) in the shift register 66a by the driver 66b according to the 8-bit data.
Has been converted to.

The signals shown in FIG. 6 and FIG.
, A pulse voltage is applied to the scan electrode 13 of the pixels of the liquid crystal display element 10 and a selected pixel is applied with the voltage of the difference between the scan electrode output and the signal electrode output described above. Writing is performed. Only the voltage of the signal electrode 14 is applied to the pixel to which the pulse voltage is not applied to the scanning electrode 13, resulting in crosstalk.

(Crosstalk) Next, crosstalk will be described. FIG. 8 shows the j-th scanning electrode 13 _j and the i-th signal electrode 1 at the time of writing for one screen of the liquid crystal display element 10.
4 _i and the voltage applied to pixel (i, j). In FIG. 8, the scanning electrode 13 _j voltage is the voltage applied to the j-th scanning electrode 13 _j , the signal electrode 14 _i voltage is the voltage applied to the i-th signal electrode 14 _i , and the pixel (i, j) voltage is The voltage applied to the pixel (i, j) is shown. Scan electrode 1
The numbers 1, 2, ..., N attached to the voltage waveforms of the _3j voltage and the pixel (i, j) voltage indicate the numbers of the scan electrodes 13,
It shows which scanning electrode 13 the pulse is applied at the time of writing. The pixel (i, j) voltage indicates all voltages applied to the pixel (i, j) during one screen display period. Of these voltages, j is used for writing.
And the other pulses 1 to j−1 and j + 1 to N are irrelevant to writing. Since the pulses 1 to j-1 are applied before writing to the pixel (i, j), they do not affect the display data after writing. Therefore, the writing pulses from j + 1 to N are crossed. Treat as a talk.

The number of crosstalk pulses received by a pixel after writing to the pixel is counted as two pulses to the signal electrode 14 used for writing one line, and is counted as one for the pixel on the j-th row of the display panel. Number of crosstalks received is N
−j times. The voltage of the pulse applied to the signal electrode 14 changes from 0 to Vfc according to the data to be displayed. As described above, the number of times of crosstalk received by each pixel varies depending on the position of the pixel, and the voltage varies depending on the display data.

In the present embodiment, in order to make the display density of each pixel uniform, the effect of crosstalk after writing data is estimated in advance, and the corrected data is adjusted so that the display density after receiving crosstalk becomes uniform. To realize a uniform display density. The calculation of the corrected data is performed by the display data correction unit 75 (see FIG. 2).

(Correction Calculation) A method of calculating a correction value for correcting deterioration of a displayed image due to crosstalk will be described below. The number of crosstalks is counted as one with two pulses applied to the signal electrode 14 when one scanning electrode 13 is selected. In FIG. 8, the pixels (i, j) are written with the j-th pulse of the liquid crystal voltage, so
The -1st pulse group does not cause crosstalk for the pixel (i, j). Crosstalk is from j + 1 to N
The second pulse. The rate of decrease in the reflectivity of the liquid crystal due to the crosstalk pulse differs depending on the crosstalk voltage and the reflectivity of the liquid crystal. The decrease rate of the reflectance of the liquid crystal when a crosstalk voltage of voltage v is applied to the pixel of reflectance t is represented by a
(T, v). Now, the reflectance Ts is applied to the pixel (i, j).
After writing (i, j), the reflectance Tc (i, j) of the pixel (i, j) when receiving the Nth crosstalk voltage from j + 1 is the Nth crosstalk pulse from j + 1. From v (i + 1) to v (N), and the reflectance immediately after receiving each crosstalk voltage is T (j + 1).
And T (N) can be calculated by the following equation (1).

T (j + 1) = Ts (i, j) · [1-a {Ts, v (j + 1)}] T (j + 2) = T (j + 1) · [1-a ｛T (j + 1), v ( j + 2)｝]... Tc (i, J) = T (N) = T (N−1) · [1-a {T (N−1), v (N)}]) (1)

Therefore, the pixel (i, j) is

T = Ts (i, j) ｛Ts (i, j) / T
c (i, j)｝

If the reflectance is written, the reflectance of the pixel becomes Ts after receiving the crosstalk. So T
s (i, j) / Tc (i, j) is referred to as a crosstalk correction value CMP (i, j) of the pixel (i, j), and the following equation (2)
It is represented by

CMP (i, j) = Ts (i, j) / Tc (i, j) (2)

Next, a method of calculating the correction value will be described. FIG.
2 shows a block diagram of the display data correction unit 75. A CPU 90 calculates a correction value and inputs and outputs signals to and from the image data memory 57 and the drive circuit control unit 58.
Reference numeral 92 denotes a memory which stores a calculation program of the CPU 90 and a reflectance reduction rate a (t, v) due to crosstalk. A bus 91 connects the CPU 90 and the memory 92. The decrease rate a (t, v) is determined by the reflectance t as described above.
And a function of the crosstalk voltage v, and is stored in the memory 92 as a table for each value of the reflectance t and the crosstalk voltage v.

FIG. 10 shows how the reflectivity of the liquid crystal decreases due to crosstalk. The vertical axis is the reflectivity of the liquid crystal, and the horizontal axis is the number of crosstalks. T1 and T2 are the maximum and minimum values of the reflectance in FIG. Crosstalk voltage is 10
The data for V and 20V are shown. As is clear from FIG. 10, the curves in the graph all fall to the right, and it can be seen that the reflectance decreases as the number of crosstalks increases. Looking at the magnitude of the crosstalk voltage, it can be seen that the drop in reflectivity is greater at a voltage of 20 V than at 10 V. When the reflectance is T2, the reflectance does not change even if crosstalk is received.

The display data in the image data memory 57 is
(I, j). Assuming that the data length of the image data memory 57 is 1 byte, T (i, j) takes an integer value from 0 to 255. The display data correction unit 75 first calculates the correction value CMP for all pixels by using Expressions (1) and (2).
Calculate (i, j). Using this, all display data T
(I, j) is multiplied by CMP (i, j) to obtain display data T
Recreate (i, j). However, the display data T (i,
Some of j) may exceed the maximum value 255 that can be represented by 1 byte. In that case, T (i,
The maximum value Tmax in j) is compared with the maximum value 255 that can be represented by 1 byte. Here, if Tmax ≦ 255, display is performed on the display panel based on the corrected display data T (i, j). When Tmax> T1, all display data T (i,
j), the following equation (3) is calculated, and the data is corrected so that all the display data falls within the display range of 0 to 255.

T (i, j) = T (i, j) / Tmax × 255 (3)

In the present embodiment, the liquid crystal display element 10 is driven by using the display data T (i, j) obtained as described above, but the display data T (i, j) is corrected. As a result, the writing voltage to the liquid crystal changes, so that the amount of crosstalk also changes. Therefore, by repeating the correction calculation using the corrected display data T (i, j), a display with higher accuracy can be performed. However, in practice, a single correction calculation can sufficiently improve the image quality, and extra time is required to repeat the correction calculation. Therefore, in this embodiment, the correction calculation is not repeated.
When the repetition of the correction calculation is terminated, the display data exceeding 255 is cut at 255.

The correction method described above will be described using a specific example. FIG. 11 shows the writing characteristics of the liquid crystal used in this embodiment. The reflectance T takes a value from T1 to T2. Assuming that the display data a is 8-bit data that takes an integer value from 0 to 255, the relationship between the reflectance T and the display data a is expressed by the following equation (4).

T = {(T 1 −T 2) / 255} × a + T 2 (4)

The number of pixels of the liquid crystal display element 10 is 480 pixels vertically and 640 pixels horizontally. FIG. 15 shows a display screen of the liquid crystal display element 10. The pixel at the upper left corner is pixel (1,1), the pixel at the lower left corner is pixel (1,480), and the pixel at the upper right corner is pixel (640,
1) The lower right corner is a pixel (640, 480).

The reflectance of the pixel (1, 1) is defined as Tm = (T1−T
2) / 2, the reflectance from pixel (1,2) to pixel (1,480) is T2, and the reflectance of pixel (2,1) is Tm = (T1
−T2) / 2, the reflectance of the pixel (2,480) is T1, and the reflectance of the other pixels is T2.

From FIG. 11, the voltage Vth of the initialization pulse of the liquid crystal is 70 (V), and the voltage of the pulse when writing the display data 255 (reflectance T1) is 70 (V).
The write pulse voltage for display data 0 (reflectance T2) is 5
0 (V) and the write voltage of the display data 128 (reflectance Tm) is 60 (V).

FIGS. 12A and 12B show, for comparison, the voltage applied to each pixel by the conventional driving method. FIG.
(A) shows the waveform of the voltage applied to the pixel (1, 1). Pulse 104 is an initialization pulse, and pulse 1
05 is a write pulse. Only these three pulses are necessary for writing, and the pulses 106 applied thereafter are crosstalk. The number of crosstalks is 479 since the number of crosstalks is from pixel (1,2) to pixel (1,480).

FIG. 12B shows the waveform of the voltage applied to the pixel (2, 1). The pulse 104 is an initialization pulse, and the pulse 105 is a write pulse. This 3
These pulses are exactly the same as the write pulses for the pixel (1, 1). However, there are no crosstalk pulses thereafter. It is from pixel (2,2) to pixel (2,48
This is because the value of the display data of 0) is 255 (reflectance T1).

FIG. 16 shows a display screen of the liquid crystal display element 10 driven by the conventional method. Pixels (1, 1), (2,
1) originally wants to display data of the same reflectance Tm. However, as described above, the pixel (1, 1) receives crosstalk and the reflectance decreases, and the pixel (1, 1) and the pixel (1, 1) The reflectances of (2) and (1) are different. Pixel (1, 1)
According to FIG. 13, the reflectance of pixel (1, 1) is 20
Since the crosstalk of (V) is received 479 times, the reflectance is T
You can see that it becomes m '. FIG. 13 shows a decrease in reflectance due to crosstalk of the liquid crystal used in this example.

In the present embodiment, the amount of decrease in the reflectance due to the crosstalk is predicted in advance, and the write data is corrected so that the reflectance to be displayed becomes the reflectance to be displayed after receiving the crosstalk.

(Specific Example of Writing) Hereinafter, an example of writing by the driving method of this embodiment will be described. First, the display data is corrected by the method already described. In this example, since the pixel that receives the crosstalk is only the pixel (1, 1), only the data is to be corrected. Pixel (1,
The display data of 1) is 128, and the corresponding reflectance is Tm when there is no crosstalk. Since this decreases to the reflectivity Tm 'due to the crosstalk, the data to be written to the pixel (1, 1) is 128 × in advance.
(Tm / Tm '). From FIG. 13, Tm / Tm '
Is 1.6, the display data 128 of the pixel (1, 1)
Is corrected to 128 × 1.6 = 205.

The reflectance corresponding to the display data 205 is represented by T
FIG. 13 shows c = (T1−T2) / 255 × 205 + T2. The write voltage corresponding to the display data 205 (reflectance Tc) is 63 (V) from FIG. FIG. 14 (A),
(B) shows the voltage applied to the pixel by the driving method according to the present embodiment.

FIG. 14A shows a waveform of a voltage applied to the pixel (1, 1). The pulse 104 is an initialization pulse, and the pulse 105 is a write pulse. In the conventional method (see FIG. 12A), the write pulse voltage is 6
Although it was 0 (V), in the present embodiment, it is 63 (V). Only these three pulses are necessary for writing the pixel, and the pulse 106 applied thereafter is a crosstalk. The number of crosstalks is pixel (1,2)
479 times, because it is from the pixel to the pixel (1,480).

FIG. 14B shows the waveform of the voltage applied to the pixel (2, 1). The pulse 104 is an initialization pulse, and the pulse 105 is a write pulse. This 3
These pulses are exactly the same as the write pulses for the pixel (1, 1). However, there are no crosstalk pulses thereafter. It is from pixel (2,2) to pixel (2,48
This is because the display data of 0) is 255 (reflectance T1).

At this time, looking at the crosstalk received by the pixel (1, 1), the number of crosstalk at a voltage of 20 V is 479 times. Therefore, it can be seen from FIG. 13 that the reflectance of the pixel (1, 1) decreases to Tc '. Here, the pixel (1,
Comparing the reflectances of (1) and (2,1), T
c ′ and Tm, which are very close values as apparent from FIG. FIG. 17 shows a display screen of the liquid crystal display element 10 driven according to the present embodiment. Pixel (1,1),
The reflectances of (2, 1) are almost the same.

(Manufacturing method of liquid crystal display element) Here, examples of manufacturing method of the liquid crystal display element other than those described above will be described. The substrate with electrodes 11 and 12 used in the above embodiment is not subjected to any processing for improving the adhesiveness between the substrate and the resin, but the following processing steps for improving the adhesiveness are performed. A method for manufacturing a liquid crystal display device including the same can be adopted.

First, a polycarbonate substrate with electrodes for sandwiching the composite film is prepared, and the electrodes are patterned into a predetermined shape. Subsequently, the surface of the patterned substrate is
Treat with r plasma for about 30 minutes. Plasma treated 2
As shown in the cholesteric phase between the substrates at room temperature,
The chiral material S- is added to the liquid crystal material MN1000XX.
811 and a mixture containing a monomer material, acrylate, and a photopolymerization initiator are quickly sandwiched together with a resin spacer. The composite film is formed by irradiating this with infrared rays to cause phase separation.

The liquid crystal display device produced by this method is:
The adhesion between the composite film and the substrate is better than that of the liquid crystal display device of the above embodiment. It is considered that the polar groups such as oxygen and nitrogen in the air were bonded to the surface of the substrate struck by the Ar plasma, particularly to the portion without the electrodes, so that the wettability of the surface was increased and the adhesion was improved. Similar effects can be obtained by using glass, PET or the like other than polycarbonate as the substrate. Further, in this manufacturing method, Ar is used as a gas used for the plasma processing, but other gases used for the plasma processing, such as oxygen, hydrogen, and nitrogen, can be used.

The following method may be used as a method for manufacturing a liquid crystal display element including a method for improving the adhesion between a substrate and a resin.
First, a polycarbonate substrate with electrodes for sandwiching the composite film is prepared, and the electrodes are patterned into a predetermined shape.
Subsequently, the surface of the patterned substrate is irradiated with an excimer laser for about 30 minutes. The chiral material S-811 is applied to the liquid crystal material MN1000XX so as to exhibit a cholesteric phase at room temperature between the two substrates subjected to excimer treatment.
And a mixture containing a monomer material, acrylate, and a photopolymerization initiator are quickly sandwiched together with a resin spacer. The composite film is formed by irradiating this with ultraviolet rays to cause phase separation.

The liquid crystal display device produced by this method is
The adhesiveness between the composite film and the substrate is better than that of the liquid crystal display device of the embodiment. This is because a polar group such as oxygen or nitrogen in the air is bonded to the surface of the substrate subjected to the excimer treatment, particularly to a portion where no electrode is provided, so that the wettability of the surface is increased and the adhesiveness is improved. Similar effects can be obtained by using glass, PET or the like other than polycarbonate as the substrate.

The following method may be used as a method of manufacturing a liquid crystal display element including a method of improving the adhesiveness between the substrate and the resin. First, a polycarbonate substrate with electrodes for sandwiching the composite film is prepared, and the electrodes are patterned into a predetermined shape. Subsequently, the surface of the patterned substrate is irradiated with ultraviolet rays for about 30 minutes. The liquid crystal material MN1000XX is applied to the chiral material S-811 so as to exhibit a cholesteric phase at room temperature between the two substrates subjected to the ultraviolet irradiation treatment.
And a mixture containing a monomer material, acrylate, and a photopolymerization initiator are quickly sandwiched together with a resin spacer. The composite film is formed by irradiating this with ultraviolet rays to cause phase separation.

The liquid crystal display device produced by this method is:
The adhesion between the composite film and the substrate is better than that of the liquid crystal display device of the above embodiment. UV-irradiated substrate surface,
In particular, since a polar group such as oxygen or nitrogen in the air is bonded to a portion having no electrode, the wettability of the surface is increased and the adhesiveness is improved. Similar effects can be obtained by using glass, PET or the like other than polycarbonate as the substrate.

(Other Embodiments) The driving method of the liquid crystal display element according to the present invention is not limited to the above embodiment, but can be variously changed within the scope of the invention.

For example, in the above embodiment, a dedicated CPU and memory are used for the data correction section. However, when the present liquid crystal display element is used as a display device such as a computer, the CPU and the memory of the computer body may be used. Good. In the above-described embodiment, two pulses of the same voltage are used as the write pulse following the initialize pulse. Writing can be performed with only one writing pulse, but writing with two pulses reduces the reflectance of the written focal conic state, so that high contrast display can be performed. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a liquid crystal display element to which a driving method according to the present invention is applied.

FIG. 2 is a block diagram showing a driving circuit for implementing a driving method according to the present invention.

FIG. 3 is a chart showing basic driving waveforms.

FIG. 4 is a graph showing a relationship between a driving voltage and a reflectance.

FIG. 5 is a chart showing voltage waveforms applied to electrodes and liquid crystal.

FIG. 6 is a chart showing signal waveforms of a scan electrode driving circuit.

FIG. 7 is a chart showing signal waveforms of a signal electrode driving circuit.

FIG. 8 is a chart showing a voltage waveform applied to a certain pixel during writing for one screen.

FIG. 9 is a block diagram illustrating a data correction unit.

FIG. 10 is a graph showing a decrease in reflectance of a liquid crystal due to crosstalk.

FIG. 11 is a graph showing writing characteristics of a liquid crystal.

12A and 12B are chart diagrams showing applied voltages when driven by a conventional method, FIG. 12A shows an applied voltage to a pixel (1, 1), and FIG. 12B shows an applied voltage to a pixel (2, 1); Is shown.

FIG. 13 is a graph showing characteristics of a liquid crystal with respect to crosstalk.

14A and 14B are chart diagrams showing applied voltages when driven by the method of the present invention, FIG. 14A shows an applied voltage to a pixel (1, 1), and FIG. 14B shows an applied voltage to a pixel (2, 1); Indicates voltage.

FIG. 15 is an explanatory diagram showing a display screen of a liquid crystal display element.

FIG. 16 is an explanatory view showing a display screen of a liquid crystal display element when driven by a conventional method.

FIG. 17 is an explanatory diagram showing a display screen of a liquid crystal display element when driven by the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display element 13 ... Scan electrode 14 ... Signal electrode 58 ... Drive circuit control part 75 ... Display data correction part 65 (65a, 65b) ... Scan electrode drive circuit 66 (66a, 66b) ... Signal electrode drive circuit

Claims (2)

[Claims] 1. A method for driving a liquid crystal display element in which a display state is switched by applying a pulse voltage to a liquid crystal exhibiting a memory property through a matrix electrode, wherein a voltage corresponding to a predetermined density is applied to each pixel and then applied. A method of driving a liquid crystal display device, comprising: calculating in advance a decrease in density due to crosstalk of a voltage, and applying a voltage corrected for the decrease to each pixel. 2. The method according to claim 1, wherein the voltage corresponding to the predetermined density is a plurality of pulses.