JP2002082349A - Liquid crystal display element, liquid crystal display, and driving method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element and a liquid crystal display device permitting interlaced scanning with resolution increased and without impairing display quality, and a driving method therefor. SOLUTION: The liquid crystal display element is provided with plural pixels LR1-C1, LR2-C1-LRm-Cn which are arranged in a matrix form, plural scanning electrodes arranged along the long side directions of the pixels and signal electrodes arranged along the directions orthogonal to the long side directions of the pixels. The dot pitch in the vertical direction is set to be 1/n times (for example, 1/1.5 times) longer than that in the horizontal direction. In the case of a factor of 1/1.5, pixels T1', V2' of an original data are displayed, by allocating them to three pixels Y1, Y2, Y3. Moreover, a picture is written in this liquid crystal display element, by the interlaced scanning which divides one frame into plural fields, and using a driving pulse for performing wiring after once resetting the liquid crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, a liquid crystal display device and a method of driving the same, and more particularly, to a liquid crystal display device in which a plurality of pixels arranged in a matrix are composed of liquid crystal.
The present invention relates to a liquid crystal display device including the element and a method for driving the element.

[0002]

2. Description of the Related Art In recent years, a liquid crystal display device using a chiral nematic liquid crystal exhibiting a cholesteric phase at room temperature has attracted attention because it has a memory property of maintaining a display state even when power supply is stopped. I have.

However, in this type of liquid crystal display device, it is necessary to reset the liquid crystal and then write an image, and it takes time until the display is completed. Until such display is completed, the portion to be rewritten has a problem that the light absorption layer, which is the background of the element, is observed as a black line (blackout), making the screen difficult to see.

An object of the present invention is to provide a liquid crystal display device, a liquid crystal display device, and a method of driving the same, which are capable of increasing the resolution and performing interlaced scanning without deteriorating the display quality.

[0005]

In order to achieve the above object, a liquid crystal display device according to a first aspect of the present invention is a liquid crystal display device having a plurality of pixels arranged in a matrix, and One of the dot pitches was 1 / n times the other (1 <n <2).

In the liquid crystal display device according to the first aspect of the invention, the resolution in one of the vertical direction and the horizontal direction is higher than that of the other, and in particular, a pixel row having a higher resolution is driven by a scanning electrode. For example, the blackout becomes inconspicuous, and interlaced scanning can be performed in a state where display quality is enhanced. For example, if n = 1.5, two pixels of the original image data can be displayed by three pixels by performing pixel interpolation, and the resolution and capacity of the image memory may be the same as before. Further, the value of n is less than 2, and the deviation in resolution between the horizontal direction and the vertical direction of the pixel is not so large, so that manufacturing is easy.

In the liquid crystal display device according to the first aspect of the present invention, it is preferable that the liquid crystal constituting the pixel has a memory property, particularly, a chiral nematic liquid crystal exhibiting a cholesteric phase. Since a relatively large screen can be manufactured at low cost and the display is maintained even if the power supply is stopped,
Energy saving can be achieved.

Further, a liquid crystal display device according to a second aspect of the present invention is a liquid crystal display device wherein the dot pitch in either the vertical direction or the horizontal direction is 1 / n times (where 1 <n <2) the other. And control means for displaying image data of a plurality of pixels by a plurality of pixels larger than the plurality of pixels in a direction in which the dot pitch is short.

In the liquid crystal display device according to the second aspect of the invention, the resolution in one of the vertical direction and the horizontal direction is higher than that of the other, and in particular, a pixel row having a higher resolution is driven by a scanning electrode. For example, the blackout becomes inconspicuous, and interlaced scanning can be performed in a state where display quality is enhanced. Further, it is the same as the liquid crystal display element according to the first aspect that it is not necessary to increase the resolution and capacity of the image memory.

In particular, image data for two pixels is continuously
In the case of displaying by pixels, of the three pixels to be displayed, the original image data can be displayed in each of the pixels on both sides, and the central pixel can be displayed with the average density of both pixels. In this case, if the control means does not store the averaged data for the center pixel in the image memory in advance and creates the averaged data when writing to the liquid crystal display element, the capacity of the image memory is increased. No need. Such control includes a shift circuit for two-line pixels, an averaging circuit for averaging the densities of the two-line pixels, and a selection for selecting whether to output data created by the averaging circuit. This is preferably realized by a control unit having a circuit.

[0011] Further, the image data of two pixels is continuously
In the case of displaying by pixels, of the three pixels to be displayed, the original image data may be displayed on each of the pixels on both sides, and the darker data of the pixels on both sides may be displayed on the center pixel. Such display is effective for displaying text data.

Further, in the liquid crystal display device according to the third invention, the dot pitch in either the vertical direction or the horizontal direction is set to 1 / n times (where 1 <n <2) the other, and the dot pitch is arranged in a matrix. A plurality of pixels, and a plurality of scanning electrodes provided along the long direction of the dot pitch of the pixels,
One frame is divided into a plurality of fields by using a plurality of signal electrodes provided along a direction in which the dot pitch of the pixel is short, and a drive pulse for resetting the liquid crystal once and writing the pixel with respect to the pixel. Driving means for writing an image by interlaced scanning.

In the liquid crystal display device according to the third aspect of the present invention, the lines along the scan electrodes during display update by interlaced scanning are finely dispersed over the entire screen, so that blackout is not noticeable and display quality is improved. .
Further, since the resolution in the arrangement direction of the signal electrodes may be lower than the resolution in the arrangement direction of the scan electrodes, it is not necessary to unnecessarily increase the number of expensive drive ICs.

Further, in a driving method according to a fourth aspect of the present invention, in the interlaced scanning, one frame is divided into a plurality of fields by using a driving pulse for resetting the liquid crystal once and writing the liquid crystal display element. To write the image. Therefore, similar to the liquid crystal display device according to the third aspect, the display quality is improved without noticeable blackout, and an inexpensive drive IC for the signal electrode can be used.

[0015]

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

(Liquid Crystal Display Device, See FIG. 1) First, a liquid crystal display device including a liquid crystal exhibiting a cholesteric phase according to an embodiment of the present invention will be described.

FIG. 1 shows a reflection type full-color liquid crystal display device using a simple matrix drive system. In the liquid crystal display element 100, a red display layer 111R for performing display by switching between red selective reflection and a transparent state is disposed on the light absorbing layer 121, and display is performed thereon by switching between green selective reflection and a transparent state. And a blue display layer 111B for performing display by selectively reflecting blue light and switching between transparent states.

Each display layer 111R, 111G, 111B
Has a structure in which a resin columnar structure 115, a liquid crystal 116 and a spacer 117 are sandwiched between transparent substrates 112 on which transparent electrodes 113 and 114 are formed, respectively. Transparent electrode 11
An insulating film 118 and an orientation control film 119 are provided on the 3, 114 as needed. Further, a sealing material 1 for sealing the liquid crystal 116 is provided on an outer peripheral portion (outside the display area) of the substrate 112.
20 are provided.

The transparent electrodes 113 and 114 are driven
C131 and 132 (see FIG. 2), and a predetermined pulse voltage is applied between the transparent electrodes 113 and 114, respectively. In response to the applied voltage, the display is switched between a transparent state in which the liquid crystal 116 transmits visible light and a selective reflection state in which visible light of a specific wavelength is selectively reflected.

The transparent electrodes 113 and 114 provided on each of the display layers 111R, 111G and 111B are composed of a plurality of strip electrodes arranged in parallel at a fine interval, and the directions of the strip electrodes are mutually different. They are opposed so as to be at right angles. Current is sequentially applied to these upper and lower strip electrodes. That is, display is performed by sequentially applying a voltage to each liquid crystal 116 in a matrix. This is referred to as matrix driving, and a portion where the electrodes 113 and 114 intersect constitutes each pixel. By performing such matrix driving for each display layer, the liquid crystal display element 10
A full color image is displayed at 0.

More specifically, in a liquid crystal display device in which a liquid crystal exhibiting a cholesteric phase is sandwiched between two substrates, display is performed by switching the state of the liquid crystal between a planar state and a focal conic state. When the liquid crystal is in the planar state, assuming that the helical pitch of the cholesteric liquid crystal is P and the average refractive index of the liquid crystal is n, light of wavelength λ = P · n is selectively reflected. Also,
In the focal conic state, the light is scattered when the selective reflection wavelength of the cholesteric liquid crystal is in the infrared light range, and transmits visible light when the wavelength is shorter than that. Therefore, by setting the selective reflection wavelength in the visible light range and providing the light absorbing layer on the side opposite to the observation side of the element, it is possible to display the selective reflection color in the planar state and display black in the focal conic state. In addition, by setting the selective reflection wavelength in the infrared light range and providing a light absorption layer on the side opposite to the observation side of the element, light in the infrared light range is reflected in the planar state, but the wavelength in the visible light range is reflected. Is transmitted, so that a black display and a white display due to scattering in the focal conic state are possible.

In the liquid crystal display element 100 in which the display layers 111R, 111G, and 111B are stacked, the blue display layer 111B and the green display layer 111G are in a transparent state in which liquid crystals are in a focal conic arrangement, and the red display layer 111R is formed of a liquid crystal. A red display can be performed by setting the array in the selective reflection state. Also, the blue display layer 111B
Is set in a transparent state in which liquid crystals are in a focal conic arrangement, and the green display layer 111G and the red display layer 111R are in a selective reflection state in which liquid crystals are in a planar arrangement, whereby yellow display can be performed. Similarly, red, green, blue, white, cyan, magenta, yellow, and black can be displayed by appropriately selecting the state of each display layer between a transparent state and a selective reflection state. Further, by selecting an intermediate selective reflection state as the state of each of the display layers 111R, 111G, and 111B, an intermediate color can be displayed, and the display layer can be used as a full-color display element.

As the liquid crystal 116, a liquid crystal exhibiting a cholesteric phase at room temperature is preferable, and a chiral nematic liquid crystal obtained by adding a chiral material to a nematic liquid crystal is particularly preferable.

The chiral material is an additive having a function of twisting the molecules of the nematic liquid crystal when added to the nematic liquid crystal. By adding a chiral material to a nematic liquid crystal, a helical structure of liquid crystal molecules having a predetermined twist interval is generated, thereby exhibiting a cholesteric phase.

Note that the memory liquid crystal itself is not necessarily limited to this configuration, and the liquid crystal is dispersed in a conventionally known polymer three-dimensional network structure, or the polymer three-dimensional structure is contained in the liquid crystal. The liquid crystal display layer can be formed as a so-called polymer dispersed liquid crystal composite film having a network structure.

(Driving circuit, see FIG. 2) As shown in FIG. 2, the pixel configuration of the liquid crystal display element 100 includes a plurality of scanning electrodes R1, R2 to Rm and signal electrodes C1, C2 to Rm.
It is represented by a matrix with Cn (m and n are natural numbers). The scan electrodes R1, R2 to Rm are connected to the output terminal of the scan drive IC 131, and the signal electrodes C1, C2 to Cn are connected to the signal drive IC.
It is connected to the output terminal of C132.

The scan drive IC 131 includes scan electrodes R1, R
A selection signal is output to a predetermined one of 2 to Rm to be in a selected state, and a non-selection signal is output to other electrodes to be in a non-selected state. The scan driving IC 131 sequentially switches the scan electrodes R1 and R2 while switching the electrodes at predetermined time intervals.
To Rm. On the other hand, signal drive IC
132 simultaneously outputs a signal corresponding to image data to each of the signal electrodes C1, C2 to Cn in order to rewrite each pixel on the scanning electrodes R1, R2 to Rm in the selected state. For example, when the scanning electrode Ra is selected (a is a natural number satisfying a ≦ m), the scanning electrode Ra and each signal electrode C1, C2
Pixels LRa-C1 to LRa-Cn at the intersection with Cn are simultaneously rewritten. Thereby, the voltage difference between the scanning electrode and the signal electrode in each pixel becomes the rewrite voltage of the pixel, and each pixel is rewritten according to this rewrite voltage.

The driving circuit includes a central processing unit 135, an image processing unit 136, an image memory 137, and an LCD controller 1.
38 and drive ICs (drivers) 131 and 132. The LCD controller 138 controls the driving IC 13 based on the image data stored in the image memory 137.
1 and 132, a voltage is sequentially applied between each scanning electrode and the signal electrode of the liquid crystal display element 100, and the liquid crystal display element 10
Write the image to 0.

Here, assuming that the first threshold voltage for untwisting the liquid crystal exhibiting the cholesteric phase is Vth1, after applying the voltage Vth1 for a sufficient time, the second threshold voltage is smaller than the first threshold voltage Vth1. When the voltage is lowered to the threshold voltage Vth2 or less, a planar state is set. When a voltage of Vth2 or more and Vth1 or less is applied for a sufficient time, a focal conic state is established. These two states are stably maintained even after the voltage application is stopped. By applying a voltage between Vth1 and Vth2, halftone display, that is, gradation display is possible.

When partial rewriting is performed, only a specific scanning line may be sequentially selected so as to include a portion to be rewritten. As a result, only necessary parts can be rewritten in a short time.

On the other hand, the image processing device 136 includes a dedicated character font storage unit 150 for storing a dedicated character font prepared in consideration of a pixel configuration in advance, and a data type determination circuit for determining the type of display data. 151 are connected.

(Pixel Configuration, See FIG. 3) FIG. 3 shows a pixel configuration in the liquid crystal display element. In this pixel configuration, as shown in FIG. 3A, the scan electrodes R1 to Rm
Of each pixel LR1-C1, LR2-C1-LRm-C by making the width of each pixel smaller than the width of the signal electrodes C1-Cn.
1 to LRm-Cn are rectangular, the scanning electrodes are provided along the long side direction of each pixel, and the signal electrodes are provided along the direction orthogonal to the long side of each pixel.

The basic pixel configuration is that the number of pixels in the vertical direction is n times the number of pixels in the horizontal direction (where 1 <n <2), and the dot pitch is 1 / n times. In other words, in this pixel configuration, it can be said that the dot pitch in the horizontal direction is n times that of the vertical method. The pixel configuration in this embodiment is n
= 1.5. Therefore, assuming that the pixel density in the horizontal direction along the arrangement direction of the signal electrodes is 100 dpi, the pixel density in the vertical direction along the arrangement direction of the scan electrodes is 150 dpi.
pi.

In such a pixel configuration, three pixels vertically arranged as shown by a dotted line in FIG.
It is displayed as a unit Y. This pixel unit Y
Indicates that the upper pixel is Y1, the middle pixel is Y2, the lower pixel is Y3 (see FIG. 3C), and the two pixels Y1 ′,
This corresponds to a pixel unit Y ′ composed of Y2 ′ (see FIG. 3B).

The aspect ratio of each pixel can be basically determined based on how many pixels of the original image data are to be displayed. In the present embodiment, two original image data are displayed by three pixels, and the aspect ratio is 1: 1.5.
It is. In other words, the vertical length of the display pixel is 2 / 3L with respect to the vertical length L of one pixel of the original image, and the display data has 1.5 times the number of pixels as compared to the original image data. The pixel pitch is set to 2/3 times.

As will be described later, it is most practical to set n = 1.5 in consideration of easy pixel complementation. However, the relationship between the ratio of the number of pixels and the dot pitch is not limited to this, and can be variously changed. For example, a configuration in which data of three pixels is displayed by four pixels may be employed.

(Display data, see FIGS. 4 and 5) Here, a display method, that is, how to allocate image data to the pixel unit Y will be described. The first display method is
This is applied when displaying an image as shown in FIG. FIG. 4B shows image data obtained by enlarging an arrow A portion of FIG. 4A, and this image data is assigned to each pixel and displayed as shown in FIG. 4C. In this case, in each pixel unit Y, the upper and lower pixels Y1, Y3
Displays the data of the original pixels Y1 'and Y2',
For the pixel Y2 in the middle stage, new display data having a density obtained by averaging the pixels Y1 and Y3 is created and displayed. This first display method is effective when the original data is an image.

In the second display method, as shown in FIG. 5, the data of the original pixels Y1 'and Y2' are displayed on the pixels Y1 and Y3, and the pixels Y1 and Y3 of the middle stage display the data of the pixels Y1 and Y3. Displays darker data. FIG. 5A shows the original data, and FIG. 5B shows a state in which the original data is assigned to each pixel and displayed by the second display method. This second
Is effective when the original data is text data.

Further, a character font may be prepared for the text data. When the text data is displayed by the second display method as shown in FIG. 5B, there is a possibility that blackout may occur depending on the character. Therefore, if the text data is displayed using a character font, a smooth display can be achieved as shown in FIG.

In the display device of the present embodiment, when the data type determination circuit 151 determines that the data to be displayed is image data, the LCD controller 138
Controls the drive IC to be displayed by the first display method.

On the other hand, when the data type determination circuit 151 determines that the data to be displayed is text data,
The CD controller 138 controls (1) the drive IC so as to be displayed by the second display method, or (2) performs display using the special character font stored in the special character font storage unit 150. Control the drive IC. Which display method is adopted may be determined according to the user's preference or the like. The display method may be selectable by the user.

Of course, the first for all the display data
Or a mode for displaying in the second display method may be selectable.

(Operation and configuration of drive IC, see FIGS. 6 and 7)
FIG. 6 shows the operation principle of the driving IC 132 for driving the signal electrodes when the first display method is executed.

When driving the upper pixel, as shown in FIG. 6A, the shift register 14 in the signal driving IC 132 is used.
The data RN to R1 of the upper pixel are input while being sequentially shifted with respect to 0. When the input of all data is completed, a voltage is applied to each signal electrode based on each data.

When driving the middle pixel, as shown in FIG. 6B, the data TN to T1 of the lower pixel are sequentially input to the shift register 140 while being shifted. At this time, the previously input data is defined as SN to S1 and the data TN
Input while taking the average of .about.T1. FIG. 6D shows the configuration of the averaging circuit 141. An average can be obtained by shifting the sum of the two inputs by one stage.

When driving the lower pixel, as shown in FIG. 6C, the data TN to T1 of the lower pixel are input to the shift register 140 while being sequentially shifted.

FIG. 7A shows the configuration of a driving IC 132 for executing the above operation. In addition to the shift register 140 and the averaging circuit 141, a selector circuit 142 for turning on and off the averaging circuit 141 is shown. Is provided.
As shown in FIG. 7B, in the case where a plurality of drive ICs 132 are cascaded to function as one IC, by turning off the averaging circuit in all the drive ICs 132,
The upper and lower pixels can be driven. Further, only the first driving IC 132 turns on the averaging circuit by the selector circuit 142 and turns off all the other averaging circuits, whereby the middle pixel can be driven.

(Driving Example 1, see FIG. 8) Next, a first example of the driving method will be described. In FIG. 8 (same in FIG. 9), rows 1 to 3 mean three scanning electrodes selected in order, and columns mean one signal electrode crossing each of the scanning electrodes. LCDs 1 to 3 mean liquid crystal layers corresponding to three pixels formed at intersections of rows 1 to 3 and columns.

The driving example 1 includes a reset period, a selection period, a sustain period, and a crosstalk (display) period. In the reset period, first, a predetermined voltage is applied to the pixel on the scan electrode to be written,
Reset the liquid crystal to homeotropic state.

The selection period is further composed of three periods (pre-selection period, selection pulse application period, and post-selection period). Part of the selection period (selection pulse application period)
Only during the pre-selection period and the post-selection period, the voltage applied to the liquid crystal is substantially zero. The selection pulse has a different voltage or pulse shape between a pixel whose planar state is to be finally selected and a pixel whose focal conic state is to be selected. When selecting the planar state, a selection pulse of a predetermined voltage is applied during the selection pulse application period.

In the subsequent sustain period, a predetermined pulse voltage is applied to the pixels on the scanning electrodes to be written. Then, the planar state is selected by setting the voltage applied to the liquid crystal to zero during the crosstalk period.

On the other hand, when it is desired to finally select the focal conic state, the voltage applied to the liquid crystal is made substantially zero during the selection pulse application period.

In the subsequent sustain period, as in the case of selecting the planar state, the liquid crystal is caused to transition to the focal conic state by applying a predetermined pulse voltage to the pixels on the scanning line to be written. In the crosstalk period, the voltage applied to the liquid crystal is set to zero as in the case where the planar state is selected. The liquid crystal in the focal conic state is fixed in the focal conic state even when the voltage is zero.

The final display state of the liquid crystal can be selected by the selection pulse applied in the middle short period of the selection period, that is, the selection pulse application period. Further, by adjusting the pulse width of the selection pulse, specifically, by changing the shape of the pulse applied to the signal electrode according to the image data, it is possible to display a halftone.

The shape of the selection pulse needs to be changed according to the image data to be displayed on the pixel to be written, and a selection pulse having a different shape must be applied to the column according to the image data. On the other hand, in the pre-selection period and the post-selection period, since a voltage of zero is always applied to the liquid crystal in the pixel, a fixed combination of pulse waveforms can be used for both the row and the column so as to obtain the voltage of zero. In the driving example 1 shown in FIG. 8, utilizing this, reset, maintenance, and display are simultaneously performed on pixels on a plurality of scan electrodes.

For example, when the LCD 2 is in the previous selection period, a pulse voltage + V1 having a different phase is applied to rows 2 and 3, and a voltage of + V1 / 2 is applied to row 1. At this time, if a pulse voltage + V1 having a phase different from that of the row 3 is applied to the column, the voltage ± VR = ±
V1 reset pulse, LCD2 voltage zero, L
A sustain pulse of voltage ± Ve = ± V1 / 2 is applied to CD1.

When the LCD 2 is in the selection pulse application period, since a data pulse (voltage + V1) of a different shape is applied from the column depending on the image data, a pulse of voltage + V1 / 2 is applied to both row 1 and row 3. LCD
1. A voltage of ± V1 / 2 is applied to the LCD 3. A pulse of voltage + V1 is applied to row 2 and a voltage difference from the data pulse applied to the column (± V1 or zero)
Is applied to the LCD 2 as a selection pulse of the voltage ± Vsel. By changing the shape of the data pulse applied to the column, the pulse width of the selection pulse can be changed.

In the subsequent selection period, the same operation as in the previous selection period is performed. That is, a pulse voltage + V1 having a different phase is applied to rows 2 and 3, and a voltage of + V1 / 2 is applied to row 1. By applying a pulse voltage + V1 having a phase different from that of the row 3 to the column, a reset pulse of voltage ± VR = ± V1 is applied to the LCD 3, a voltage of zero is applied to the LCD 2, and a sustain pulse of voltage ± Ve = ± V 1/2 is applied to the LCD 1. Apply.

During the periods other than the reset period, the selection period, and the sustain period, a waveform having the same phase as the data pulse applied from the signal electrode during the pre-selection period and the post-selection period of the other scan electrodes is applied to each scan electrode. And a pulse of voltage + V1 / 2 is applied during the selection pulse application period of the other scan electrodes. Thus, a crosstalk voltage of ± V1 / 2 is applied to the liquid crystal in this portion with the same pulse width as the selection pulse in accordance with the image data. This crosstalk voltage does not affect the display state of the liquid crystal because the pulse width is narrow.

An image can be displayed by repeatedly applying the above-described pulse voltage to each scanning electrode sequentially. Further, since the reset pulse, the selection pulse, and the sustain pulse can be applied to an arbitrary scanning electrode, partial rewriting can be performed.

Next, a second example of the driving method will be described. Here, a signal voltage that sequentially selects transmission, halftone, and total reflection is input to the signal electrode.

In order to facilitate understanding, FIG.
Although the reset period and the sustain period are shown as twice the selection time, in practice, it is desirable to secure a sufficiently long time so that the state selected in the reset or the selection period is correctly established. The time is set to be sufficiently long (for example, several tens of times) as compared with the period and the selected pulse width.

In the driving example 2, similarly to the driving example 1, the selection period is divided into a selection pulse application time and a pre-selection time and a post-selection time before and after the selection pulse application time. The length of the pre-selection time and the post-selection time is the selection pulse width (selection pulse application time)
(1 in FIG. 9).

In this case, each scanning electrode (rows 1, 2, 3)
Include a reset voltage ± V1, a select voltage ± V2, and a sustain voltage ±
V3 is applied, and the lengths of the reset period and the sustain period are as follows:
Each is an integral multiple of the selection pulse application time (two times in FIG. 9)
To The voltage is set to 0 V during the display (crosstalk) period. On the other hand, a pulse waveform of voltage ± V4, the phase of which is shifted according to the image data, is applied to the signal electrode (column).

In driving example 2, the voltage applied to the column ±
The waveform of the selection pulse is determined based on the phase and voltage value of V4 and the selection voltage ± V2. When the phase of the voltage ± V4 is the same as the selection voltage ± V2, the selection pulse becomes ± (V2−V4) and is transmitted ( Focal conic state) is selected, and in the case of the opposite phase, a selection pulse of ± (V2 + V4) results and the selective reflection (planar state) is selected. The values of the electrodes V2 and V4 are appropriate values for selecting transmission and reflection.
In addition, the value of the voltage V4 that causes crosstalk is a value within a predetermined threshold value that changes the state of the liquid crystal.

In the driving example 2, scanning is performed with a shift by the selection pulse application time (that is, the selection pulse application time is equal to the scanning time). Therefore, the time required for scanning one screen is shorter than that in driving example 1 (ie,
Scanning speed is fast).

(Interlaced Scanning) Hereinafter, a driving method by interlaced scanning will be described with reference to scanning examples 1 and 2. Interlaced scanning is opposed to line-sequential scanning, and refers to a form in which one or more scanning lines are skipped and scanned to write one screen (frame).

(Scanning Example 1, see FIGS. 10 to 12) In this scanning example 1, one frame is divided into three fields.
Writing is sequentially performed on each scanning line in the order of the second and third frames, and an image of one frame is displayed. As shown in FIG. 11, the writing in each scanning line is composed of a reset period, a selection period, and a sustain period. In these three periods, the liquid crystal display element is a blackout in which the light absorption layer on the back surface is visually observed. State. Thereafter, the liquid crystal maintains the display state.

In the case of the matrix drive, since a crosstalk occurs due to a pulse of the previous selected line, FIG.
In the display period, crosstalk actually occurs during the rewriting of the screen.

In some cases, the display may not appear immediately after the end of the sustain period, depending on the type of liquid crystal, etc. In this case, the delay period from the end of the sustain period to the start of the display is measured in advance, and the actual driving is performed. In this case, the delay time may be reflected.

In this scanning example 1, writing (reset, selection, and maintenance) is started at fixed time intervals for each scanning line, and writing of the next field is performed based on the end timing of the reset period in the last line of the previous field. Start.

As shown in FIG. 10, when each scan line alternates between the blackout state and the display state at equal time intervals, an image display having the same brightness on average is approached.
Flicker can be reduced. For this purpose, if the number of scan lines included in the rewrite target area is not large with respect to the length of the blackout time of one scan line, the next field is set at the end of the blackout of the first line of the previous field. Scanning may be started. When the number of scan lines is longer than the length of the blackout time of one scan line, the length of the sustain period in the scan lines of the first field may be adjusted.

In the first scanning example, the rewriting of the second field is started at the same time when the blackout of the last line of the first field is completed by extending the sustain period.

FIGS. 12A and 12B show how the display shown in FIG. 4C is executed in the first scanning example. FIG. 12A shows the state where the first field is written, and FIG. 12B shows the state where the second field is written. (C) shows a state in which the third field is being written.

(Scanning Example 2, see FIGS. 13 and 14) In this scanning example 2, one frame is divided into two fields of an odd number and an even number. First, writing is performed on an odd number of scanning lines. And writing is performed on the scan line of the frame, and an image of one frame is displayed.

Also in this scanning example 2, writing (reset, selection, and maintenance) is performed at fixed time intervals for each scanning line.
Is started, and writing of the next field is started based on the end timing of the reset period in the last line of the previous field. In other words, under the condition that the selection period * A of the last line of the first field * A and the selection period * B of the first line of the second field are shifted, the rewriting of the odd field and the even field can be made close to each other. Fields are partially overlapped.

FIG. 14 shows the manner in which the display shown in FIG. 4C is executed in the second scanning example. FIG. 14A shows a state in which odd fields are written, and FIG. 14B shows a state in which even fields are written. Indicates the status.

(Other Embodiments) The liquid crystal display device, the liquid crystal display device and the method of driving the liquid crystal display device according to the present invention are not limited to the above embodiments, but may be variously modified within the scope of the invention. it can.

In particular, the configuration, material, manufacturing method, and configuration of the driving circuit of the liquid crystal display element are arbitrary. The shape of the pulse waveform and the application timing shown as the driving method are, of course, examples.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a liquid crystal display device according to the present invention.

FIG. 2 is a block diagram showing a driving circuit of the liquid crystal display element.

3A and 3B show a pixel configuration, FIG. 3A is a chart showing a pixel configuration in the present embodiment, FIG. 3B is a chart showing a pixel configuration of image data, and FIG. 3C is one unit in the present embodiment; FIG. 2 is a chart showing a pixel configuration of FIG.

FIGS. 4A and 4B show allocation of data to each pixel in a first display method, FIG. 4A is a diagram showing an original image, and FIG. 4B is a chart showing image data obtained by enlarging a part of the image in FIG. FIG. 3C is a chart showing a state in which the data of FIG.

5A and 5B show allocation of data to each pixel in the second display method, FIG. 5A is a chart showing original data, and FIG. 5B shows a state in which the data of FIG. FIG. 7C is a chart showing an allocation state when a character font is used.

FIGS. 6A, 6B, and 6C are block diagrams showing shift registers for explaining the operation principle of a driving IC;
(D) is a block diagram showing an averaging circuit.

FIG. 7A is a block diagram illustrating a configuration example of a driving IC.
(B) is a block diagram showing a state in which drive ICs are cascaded.

FIG. 8 is a chart showing driving waveforms in driving example 1.

FIG. 9 is a chart showing a driving waveform in Driving Example 2.

FIG. 10 is a chart showing an example 1 of interlaced scanning.

FIG. 11 is a chart showing a writing period to one pixel.

FIG. 12 is a chart showing a display state in scanning example 1.

FIG. 13 is a chart showing an example 2 of interlaced scanning.

FIG. 14 is a chart showing a display state in scanning example 2;

[Explanation of symbols]

 Reference Signs List 100 liquid crystal display elements 113, 114 electrodes 116 chiral nematic liquid crystal 131, 132 drive IC (driver) 135 central processing unit 141 averaging circuit LR1-C1 to LRm-Cn pixel Y pixel unit Y1, Y2 , Y3... Upper, middle, and lower pixels

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/20 622 G09G 3/20 622N 5C094 631 631P 641 641P 642 642A 642K 642L 650 650M 3/36 3/36 (72) Inventor Katsuhiko Asai 2-3-1, Azuchi-cho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka International Building Minolta Co., Ltd. (reference) 2H088 HA06 JA14 MA03 MA13 2H092 GA13 NA25 PA03 PA06 QA11 2H093 NA41 NA51 NB01 NC22 ND06 ND07 ND20 NF14 5C006 AA22 AC15 AC29 AF23 AF31 AF44 AF46 AF47 AF53 AF85 BA11 BB11 BF02 BF13 BF14 FA22 FA56 GA03 5C080 AA10 BB05 BB08 CC03 DD05 DD06 DD22 EE29 EE30 JJ01 JJ02 JJ06 5C09AAAAA19A48A08AA19A48A08AA19AA19 DB02 DB04 EA04 EA05 EB02 FA01 FA02 GA10 JA01

Claims (15)

[Claims] 1. A liquid crystal display device having a plurality of pixels arranged in a matrix, wherein a dot pitch in one of a vertical direction and a horizontal direction is 1 / n times the other (where 1 <n <2). A liquid crystal display device characterized by the following. 2. The liquid crystal display device according to claim 1, wherein n = 1.5. 3. The liquid crystal display device according to claim 1, wherein the liquid crystal forming the pixel has a memory property. 4. The liquid crystal display device according to claim 3, wherein the liquid crystal having a memory property is a chiral nematic liquid crystal exhibiting a cholesteric phase. 5. A liquid crystal display element in which the dot pitch in either the vertical direction or the horizontal direction is 1 / n times (where 1 <n <2) the other, and a plurality of pixels in the short dot pitch direction. And a control unit for displaying the image data of (a) on a plurality of pixels larger than the plurality of pixels. 6. The liquid crystal display device wherein n = 1.5,
6. The liquid crystal display device according to claim 5, wherein said control means displays image data of two pixels in three consecutive pixels in the direction of shorter dot pitch. 7. The control means displays the original image data in each of the pixels on both sides of the three consecutive pixels for displaying image data of two pixels, and displays the original image data in the center pixel. 7. The liquid crystal display device according to claim 6, wherein the image is displayed at an average density. 8. The liquid crystal display device according to claim 8, wherein the control unit does not store the averaged data for the center pixel in an image memory in advance, but creates the averaged data when writing to the liquid crystal display element. Item 8. A liquid crystal display device according to item 7. 9. The control means includes a shift circuit for pixels on two lines, an averaging circuit for averaging the densities of the pixels on the two lines, and whether to output data created by the averaging circuit. 8. The liquid crystal display device according to claim 7, further comprising: a selection circuit for selecting a selected one. 10. The control means displays the original image data in each of the pixels on both sides of the three consecutive pixels, and displays the data of the darker density of the pixels on both sides in the center pixel. 7. The liquid crystal display device according to claim 6, wherein: 11. A display apparatus further comprising: a determination unit configured to determine a type of display data, wherein when the display data is text data, the control unit performs control to display data of a high density on a central pixel. The liquid crystal display device according to claim 10. 12. A display device further comprising: a determination unit configured to determine a type of display data; and a storage unit configured to store a dedicated character font prepared in consideration of a pixel configuration in advance. 11. The liquid crystal display device according to claim 10, wherein the control means controls the display using the special character font. 13. The dot pitch in either the vertical direction or the horizontal direction is 1 / n times that of the other (1 <n <2).
A plurality of pixels arranged in a matrix, a plurality of scanning electrodes provided along a long dot pitch direction of the pixel, and a plurality of signals provided along a short dot pitch direction of the pixel An electrode; and driving means for writing an image by interlaced scanning that divides one frame into a plurality of fields by using a drive pulse for resetting liquid crystal once and writing the pixel. Liquid crystal display device. 14. An image is written in the liquid crystal display element according to claim 1 by interlaced scanning for dividing one frame into a plurality of fields by using a drive pulse for resetting the liquid crystal once and writing. Characteristic driving method. 15. The driving method according to claim 13, wherein, in the case of text data, display is performed using a dedicated font prepared in consideration of a pixel configuration in advance.