JP2000122619A - Driving method of liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce electric power consumption more than whole image screen display time by stopping operation for scanning of a scanning electrode driving circuit corresponding to the undisplayed part at partial display time. SOLUTION: In various driving techniques in a partial display, a frame period of a period N.τ is divided into a first period of the first half period n.τ and a second period of a residual period (N-n).τ. Selective electric potential of a period τ of the first period is impressed on scanning electrodes COM1 to COMn of the display part while successively making time different to always hold nonselective electric potential in an unimpressed period of the selective electric potential. Scanning electrodes COMn+1 to COMN of the undisplayed part always hold nonselective electric potential over the whole frame period. Electric potential decided similarly to whole image screen display time in the correspondence between display data of a picture element of an intersection of the signal electrode and the scanning electrodes COM1 to COMn and selective electric potential of the scanning electrodes, is impressed on signal electrodes SEG1 to SEGM in the first period. Predetermined prescribed electric potential is impressed in the second period.

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 device. More specifically, the present invention relates to a method for driving a simple matrix panel using an STN liquid crystal or the like. More specifically, the present invention relates to a driving method suitable for performing display on only a part of a display screen.

[0002]

2. Description of the Related Art A liquid crystal display panel has a structure in which liquid crystal is sandwiched between a glass substrate on which a plurality of scanning electrodes are formed and a glass substrate on which a plurality of signal electrodes are formed. FIG. 2 is a view showing an arrangement of electrodes of the liquid crystal display panel. N scanning electrodes are provided from COM 1 to COM N, and signal electrodes are provided as SE.
There are M lines from G1 to SEG M. The scanning electrodes and the signal electrodes are arranged in a matrix, and NM intersections between the N scanning electrodes and the M signal electrodes become display pixels.

As shown in FIG. 2, normally, a selection voltage is applied to a pixel whose display is to be turned on among the N · M pixels, and the selected pixel is selected, and a non-selection voltage is applied to a pixel whose display is to be turned off. Display is performed on the entire screen as a non-selected pixel by applying the voltage. This is hereinafter referred to as “full screen display”. Here, when the amount of information to be displayed is small, for example, when only time display or simple message display is performed, the display can be performed by using only a part of the screen. At this time, it is possible to apply a non-selection voltage to pixels in an area not used for display while maintaining the same drive as that for full screen display. It consumes the same power. In many cases, such as time display is always performed, so the power consumption at this time determines the continuous use time of the device, especially when the liquid crystal display element is mounted on a portable electronic device driven by a battery. One of the main factors.

Therefore, when display is possible by using only a part of the screen, the driving method may be changed from that for full screen display to reduce power consumption. This is hereinafter referred to as “partial display”. FIG. 3 shows an example of the partial display. As shown in FIG. 3, at the time of partial display, display is performed by applying a selection voltage or a non-selection voltage to pixels on the scan electrodes from COM1 to COMn (hereinafter referred to as a display unit), while the remaining COM (n
Only a voltage equal to or lower than the non-selection voltage is applied to pixels on the scanning electrodes from +1) to COMN (hereinafter referred to as a non-display portion), and display is not performed. Here, n is an integer satisfying 1 ≦ n <N. In FIG. 3, the non-display portion is located at the top of the screen, but the position of the non-display portion can be changed by changing the corresponding scanning electrode.

[0005] As a method of performing such partial display,
For example, there is a method of switching from 1 / N duty driving during full screen display to 1 / n duty driving during partial display. At this time, from COM 1 to COM
A selection voltage of 1 / n duty drive is applied to the scan electrodes up to n, and the remaining scan electrodes from COM (n + 1) to COM N always hold the non-selection potential. At this time, the voltage applied to the non-display portion can be made smaller than the non-selection voltage of the display portion by appropriately selecting the ratio between the scanning electrode selection potential during partial display and the potential applied to the signal electrode. Further, according to this method, the driving frequency and the scanning electrode selection potential are both reduced during partial display as compared with full screen display, and the scan electrode driving circuit corresponding to the non-display section is used for scanning during partial display. Since the operation can be stopped, the effect of reducing power consumption is great.

[0006]

However, this method has the following disadvantages. That is, as n becomes smaller than N, the difference between the scan electrode selection potentials of 1 / N duty drive and 1 / n duty drive increases. Therefore, in order to switch between full-screen display and partial display by one driver IC, the operating voltage range of the driver IC must be greatly expanded as compared with the case where only full-screen display is performed. Difficult to manufacture and IC
However, there are disadvantages such as an increase in chip area and an increase in cost. Also, every time you switch between full screen display and partial display,
There was also a trouble such that the scanning electrode selection potential had to be adjusted, and when n changed, the ratio between the scanning electrode selection potential and the potential applied to the signal electrode had to be changed.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a method of performing partial display at the same scan electrode selection potential as at full screen display or at scan electrode selection potential close to full screen display. It is another object of the present invention to reduce power consumption during partial display compared to full screen display. The following measures were taken in order to achieve this purpose.

Method 1 In a method for driving a matrix type liquid crystal display element comprising N scanning electrodes (N is an integer of 2 or more) and a plurality of signal electrodes, the method has a first mode and a second mode, In the mode, the selection potential in the period τ is applied L times (L is a natural number) per frame to all the scanning electrodes, and the non-selection potential is always held during the period in which the selection potential is not applied. The potential determined by the correspondence between the display data of the pixel at the intersection with the electrode and the selection potential of the scanning electrode is applied.
N scan electrodes (n is an integer such that n <N)
And a second scan electrode group consisting of the remaining (N-n) scan electrodes, and the frame period is divided into a first period and a second period. A selection potential in a period τ is applied L times per frame to each scanning electrode of one scanning electrode group during a first period, and a non-selection potential is always held during a period in which no selection potential is applied in the first period. , The second period always holds the non-selection potential, each scan electrode of the second scan electrode group always holds the non-selection potential over the entire frame period, and the signal electrode has the signal electrode during the first period. Applying a potential determined by the correspondence between the display data of the pixel at the intersection with each scanning electrode of the first scanning electrode group and the selection potential of the scanning electrode,
In the second period, a predetermined potential is applied.

Method 1 (1) In the method of driving a liquid crystal display element of method 1, when the selection potential of the scan electrode is set to the same value in the first mode and the second mode, the effective voltage applied to the selected pixel is set. In the second mode, the potential applied to the signal electrode in the second period is determined so that the voltage is equal between the first mode and the second mode.

Method 1 (2) In the liquid crystal display element driving method of method 1 or 2, the polarity of the potential applied to the signal electrode in the second mode in the second period is half or almost half of the signal polarity. It is inverted between the electrode and the remaining signal electrode. Method 1 (3) In the liquid crystal display element driving method of Method 1 or 2, the polarity of the potential applied to the signal electrodes in the second mode in the second mode is inverted for each adjacent signal electrode.

Method 1 (4) In the liquid crystal display element driving method of Method 1, the potential applied to the signal electrode in the second mode in the second period is set as the non-selection potential of the scanning electrode. Method 2 A method for driving a matrix-type liquid crystal display element including N scanning electrodes (N is an integer of 2 or more) and a plurality of signal electrodes has a first mode and a second mode. The selection potential in the period τ is applied L times (L is a natural number) per frame to all the scanning electrodes, and is kept at the non-selection potential during the period in which the selection potential is not applied. A potential determined by the correspondence between the display data of the pixel at the intersection and the selection potential of the scanning electrode is applied.
N scan electrodes (n is an integer such that n <N)
And a second scan electrode group consisting of the remaining (N-n) scan electrodes, and the frame period is divided into a first period and a second period. A selection potential of a period τ is applied to each scanning electrode of one scanning electrode group L times in each frame during a first period, and a non-selection potential is always held during a period when no selection potential is applied in the first period. In the second period, the selection potential in the period of ατ (0 <α ≦ 1) is applied L times for each frame, and in the second period, the non-selection potential is always held during the period in which the selection potential is not applied. Each scan electrode of the two scan electrode groups always holds a non-selection potential over the entire frame period, and the signal electrode has a pixel at the intersection of the signal electrode and each scan electrode of the first scan electrode group during the first period. And the potential determined by the correspondence between the display data and the selection potential of the scanning electrode. Applying a non-selection potential of the scan electrodes.

Method 2 (1) In the method of driving a liquid crystal display element of method 2, when the selection potential of the scanning electrode is set to the same value in the first mode and the second mode, the effective voltage applied to the selected pixel is set. The value of α is selected so that the voltage is equal in the first mode and the second mode. Method 2 (2) In the method of driving the liquid crystal display element of method 2, α = 1.

Method 3 In a method for driving a matrix type liquid crystal display element comprising N scanning electrodes (N is an integer of 2 or more) and a plurality of signal electrodes, the method has a first mode and a second mode, In the mode, the selection potential in the period τ is applied L times (L is a natural number) per frame to all the scanning electrodes, and the non-selection potential is always held during the period in which the selection potential is not applied. A potential determined according to the display data of the pixel at the intersection with the electrode is applied, and in the second mode, N scan electrodes are replaced with a first scan composed of n scan electrodes (n is an integer of n <N). The first scan electrode group is divided into a first scan electrode group and a second scan electrode group including a second scan electrode group including the electrode group and the remaining (N−n) scan electrodes. Each scanning electrode has a selection potential (1 <β ≦ 2, n <
N / β) is applied L times for each frame. In the first period, the non-selection potential is always held during the period when the selection potential is not applied, and the second period is always held at the non-selection potential. Each scan electrode of the scan electrode group always holds a non-selection potential over the entire frame period, and the signal electrode displays a pixel at the intersection of the signal electrode and each scan electrode of the first scan electrode group during the first period. A potential determined by the correspondence between the data and the selection potential of the scan electrode is applied, and a non-selection potential of the scan electrode is applied in the second period.

Method 3 (1) In the method of driving a liquid crystal display element of method 3, when the selection potential of the scanning electrode is set to the same value in the first mode and the second mode, the effective voltage applied to the selected pixel is set. A method of driving a liquid crystal display element, wherein a value of β is selected so that a voltage is equal between a first mode and a second mode.

Method 3 (2) In the method of driving a liquid crystal display element of method 3, β = 2. According to the liquid crystal display element driving method of the present invention, full-screen display can be performed in the first mode, and partial display can be performed in the second mode. Further, in the partial display method of the present invention, the scan electrode driving circuit corresponding to the non-display portion can stop the operation for scanning at the time of partial display, and the signal electrode drive circuit is turned on during the second period at the time of partial display. This eliminates the need for transfer of display data and the conversion of display data to drive output in the signal electrode drive circuit, and the voltage applied to the non-display section can be made lower than the non-selection voltage for full-screen display. The power consumption of the display element driver circuit can be reduced.

Further, in the partial display method of the present invention, partial display can be performed at the same scan electrode selection potential as in full screen display or at scan electrode selection potential close to full screen display.
Therefore, even when switching between full screen display and partial display is performed by one driver IC, the operating voltage range of the driver IC may be substantially the same as in the case where only full screen display is performed, and the chip area of the IC increases. The problem does not occur. Also, even if you switch between full screen display and partial display,
Adjustment of the scanning electrode selection potential is hardly necessary. Further, even if the number n of the common electrodes in the partial display section changes, it is almost unnecessary to change the ratio of the scanning electrode selection potential to the potential applied to the signal electrode or the scanning electrode selection potential.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. (Embodiment 1) A driving method in full-screen display will be described with reference to FIGS. FIG. 4 shows an example of scan electrode drive waveforms and signal electrode drive waveforms when full-screen display is performed by line-sequential driving (one-line selection driving). The selection potential of the scanning electrode is + VC or -VC, and the non-selection potential of the scanning electrode is 0 potential. COM 1, COM 2, COM 3, ...
The scan electrode selection potential for the period τ is applied while shifting the time in the order of, and when the application to COM N is completed, one scan is completed. A period required for one scan is called a frame period, and has a length of N · τ.

On the other hand, the signal electrode has a signal electrode selection potential when a pixel on the scanning electrode to which the scanning electrode selection voltage is applied is selected (display ON), and a signal electrode is selected when the pixel is not selected (display OFF). Apply a non-selection potential. Here, when the scanning electrode selection potential is + VC, the signal electrode non-selection potential is + V
S, when the signal electrode selection potential is -VS, and when the scanning electrode selection potential is -VC, the signal electrode non-selection potential is -VS and the signal electrode selection potential is + VS. The polarity of each drive waveform is inverted every frame to prevent deterioration of the liquid crystal display panel.

FIG. 5 shows the difference between the potentials applied to the scanning electrodes and the signal electrodes at this time, that is, the voltages applied to the display pixels. When the effective value of the voltage applied to the display pixel is expressed by an equation, the non-selection voltage VOFF and the selection voltage VON are respectively VOFF = {(VC−VS) ² / N + (N−1) · VS ² / N} ^{1 / 2} (Equation 1) VON = {(VC + VS) ² / N + (N−1) · VS ² / N} ^1/2 (Equation 2) Next, various driving methods in partial display will be described.

Method 1 As shown in FIG. 6, the frame period of the period N · τ is divided into a first period of the first half period n · τ and a second period of the remaining period (N−n) · τ. . In the first period, the selection potential in the period τ is applied to the scan electrodes (COM 1 to COM n) of the display unit while sequentially shifting the time. The non-selection potential is always maintained during the period when the selection potential is not applied.

Scanning electrodes (COM n + 1 to COM n + 1)
COM N) always holds the non-selection potential throughout the frame period.・ In addition, signal electrodes (SEG1-SEG)
EGM) includes, in the first period, the correspondence between the display data of the pixel at the intersection of the signal electrode and the scanning electrode (COM1 to COMn) and the selection potential of the scanning electrode in the same manner as in full-screen display. Is applied. In addition, a predetermined potential is applied in the second period.

As in the case of full-screen display, the polarity of each drive waveform is inverted for each frame to prevent deterioration of the liquid crystal display panel. Method 1 (1) When the selection potential of the scan electrode is set to the same value in the full screen display and the partial display in the method 1, the effective voltage applied to the selected pixel changes between the full screen display and the partial display. The potential to be applied to the signal electrode during the second period during partial display is determined so as to be equal. For this purpose, the potential applied to the signal electrode during the second period during the partial display may be the same as that during the full-screen display, and the display data assumed in the non-display portion at that time is arbitrary. Therefore, for low power,
It is desirable to select the signal electrode selection potential or the signal electrode non-selection potential so that the potential change during the second period is as small as possible. As an example, FIG. 6 shows a signal electrode drive waveform when a signal electrode non-selection potential is applied over the entire period during the second period.

At this time, the difference between the potentials applied to the scanning electrodes and the signal electrodes, that is, the voltage applied to the display pixels is shown in FIG.
Shown in At this time, the non-selection voltage of the display unit, the selection voltage, and the effective value of the applied voltage of the non-display unit are set to VOFF, respectively.
1, VON1, and When VN1, VOFF1 = {(VC- VS) 2 / N + (N-1) · VS 2 / N} 1/2 ( number 3) VON1 = {(VC + VS) 2 / N + ( N-1) · VS ² / N} ^1/2 (Equation 4) VN1 = VS (Equation 5) Method 1 (2) Applying to a plurality of signal electrodes during partial display in method 1 (1) during the second period The polarity of the potential is inverted between half or almost half of the signal electrodes and the remaining signal electrodes. For example, a signal electrode non-selection potential is applied to all or a half of the entire signal electrodes during the second period, and a signal electrode selection potential is applied to all of the remaining signal electrodes during the second period. I do. As a result, the charge and discharge currents of the liquid crystal display element cancel each other, so that the power consumption of the drive circuit can be reduced. At this time, the non-selection voltage of the display unit, the selection voltage, and the effective value of the applied voltage of the non-display unit are the same as those in the method 1 (1).

Method 1 (3) In the method 1 (1), the polarity of the potential applied to the plurality of signal electrodes in the second period is inverted for each adjacent signal electrode during partial display. For example, a signal electrode non-selection potential is applied to the odd-numbered signal electrodes throughout the second period,
A signal electrode selection potential is applied to the even-numbered signal electrodes throughout the second period. As a result, the charge and discharge currents of the liquid crystal display element cancel each other, so that the power consumption of the drive circuit can be reduced. At this time, the non-selection voltage, selection voltage,
The effective value of the applied voltage of the non-display part is calculated by the method 1 (1)
Is the same as

Method 1 (4) The potential applied to the signal electrode during the second period in the partial display in the method 1 is defined as a scanning electrode non-selection potential. FIG. 8 shows the scan electrode drive waveform and the signal electrode drive waveform at this time. FIG. 9 shows the difference between the potentials applied to the scanning electrodes and the signal electrodes at this time, that is, the voltages applied to the display pixels.
At this time, the effective values of the non-selection voltage of the display unit, the selection voltage, and the applied voltage of the non-display unit are VOFF2 and VO, respectively.
N2, and if the VN2, VOFF2 = {(VC- VS) 2 / N + (n-1) · VS 2 / N} 1/2 ( number 6) VON2 = {(VC + VS) 2 / N + (n- 1) · VS ² / N} ^1/2 (Equation 7) VN2 = VS · (n / N) ^1/2 (Equation 8) When N = 240, VC is common during full screen display and partial display.
= 18.12 (V), VS = 1.17 (V),
Computing each voltage when n = 8, 16, 32, 64, and 120, and comparing full screen display, method 1 (1), and method 1 (4),

[0026]

[Table 1]

In the method 1 (1), the non-selection voltage and the selection voltage in the partial display are the same as those in the full-screen display regardless of n.
The non-display portion applied voltage is about 68% of the non-selection voltage. Therefore, the display can be performed with the same contrast ratio as in the full-screen display even in the partial display, and the voltage applied to the non-display portion is reduced as compared with the full-screen display. In the method 1 (4), the non-display portion applied voltage is lower than in the method 1 (1), but the non-selection voltage and the selection voltage in the partial display are lower than in the full screen display. Further, as n becomes smaller, each voltage at the time of partial display also becomes smaller. Therefore, VC,
If the VS is kept constant, the voltage of the partial display becomes insufficient,
Since the display is not performed, it is necessary to make VC and VS larger in partial display than in full screen display.

As described above, although the method 1 (4) has an advantage that the non-display portion applied voltage can be made smaller than that of the method 1 (1), VC and VS are required for displaying on the partial display portion.
Has to be made larger than in full-screen display. Therefore, the following methods 2 and 3 have attempted to improve the disadvantage. Method 2 As shown in FIG. 1, the frame period of the period N · τ is divided into the first period of the first half period n · τ and the second period of the remaining period (N−n) · τ.

Scanning electrodes of the display section (COM 1 to COM
In n), the selection potential of the period τ is applied while sequentially shifting the time during the first period, and the selection potential (0 <α ≦ 1) of the period α · τ is applied during the second period. The non-selection potential is always maintained during the period when the selection potential is not applied. -Scan electrode of non-display part (COM n + 1 to COM N)
Keeps the non-selection potential at all times during the entire frame period.

The signal electrodes (SEG1-SEG)
M) has its signal electrode and scan electrode (CO
A potential determined in the same manner as in the case of full-screen display is applied by the correspondence between the display data of the pixel at the intersection with M 1 to COM n) and the selection potential of the scanning electrode. In addition, a scanning electrode non-selection potential is applied in the second period. As in the case of full screen display, the polarity of each drive waveform is inverted for each frame to prevent deterioration of the liquid crystal display panel.

At this time, the difference between the potentials applied to the scanning electrodes and the signal electrodes, that is, the voltage applied to the display pixels is shown in FIG.
0 is shown. The effective values of the non-selection voltage of the display unit, the selection voltage, and the applied voltage of the non-display unit are VOFF3 and VO, respectively.
N3, and when the VN3, VOFF3 = {(VC- VS) 2 / N + (n-1) · VS 2 / N + α · VC 2 / N} 1/2 ( number 9) VON3 = {(VC + VS ) ² / N + (n−1) · VS ² / N + α · VC ² / N} ^1/2 (Equation 10) VN3 = VS · (n / N) ^1/2 (Equation 11) Method 2 (1) When the selection potential of the scanning electrode is set to the same value in the full screen display and the partial display in the method 2, α is set so that the effective voltage applied to the selected pixel is equal between the full screen display and the partial display. Determine the value of VC at partial display and V at full screen display
When C is set to the same value and VS at the time of partial display and VS at the time of full screen display are set to the same value, the condition for equalizing the selected voltage is as follows: VON3 = VON, α = (Nn) · (VS / VC) ² (Equation 12) When N = 240, VC is common to both full screen display and partial display.
= 18.12 (V), VS = 1.17 (V),
Computing each voltage when n = 8, 16, 32, 64, and 120, and comparing full screen display, method 1 (1), and method 2 (1),

[0032]

[Table 2]

According to the method 2 (1), the non-display portion applied voltage can be reduced as compared with the method 1 (1) while maintaining the same non-selection voltage and the same selection voltage as in full-screen display. The smaller the value of n, the greater the effect of reducing the non-display portion applied voltage. For example, when n = 8, the non-display portion applied voltage in the method 2 (1) is about 13% of the non-selection voltage during full screen display. When n = 8, the applied voltage of the non-display portion in the method 2 (1) is about 18% of the applied voltage of the non-display portion in the method 1 (1).

Here, in FIG. 1, the selection potential in the period α is CO
Although the same phase is applied to the scan electrodes from M1 to COMn, the phase can be arbitrarily selected within the second period. For example, a different phase may be set for each scanning electrode, and the applied voltage at that time is the same as that at the same phase. Method 2 (2) In method 2 (1), in order to make VC and VS the same voltage during partial display and full screen display, and to make the selection voltage the same, the value of α is an integer as shown in Table 2. Absent. Therefore,
The drawback is that the basic clock for creating the display timing must be higher than that for full-screen display, which increases the power in that part and complicates the configuration of the frequency divider circuit for creating the display timing. There is.

Therefore, in order to improve the above-mentioned disadvantage, in method 2 (2), α = 1 is fixed in method 2.
When α is fixed to 1, the period of the selection potential applied to the scanning electrode is equal to τ, so that the display timing of a higher frequency than in the full screen display is unnecessary. When N = 240, VC = 18.12 is common to both full screen display and partial display.
(V), VS = 1.17 (V), n = 8, 1
Computing each voltage at 6, 32, 64 and 120 and comparing full screen display, method 1 (1) and method 2 (2),

[0036]

[Table 3]

In the case of the method 2 (2), the non-display portion applied voltage is the same as that of the method 2 (1), and both the selection voltage and the non-selection voltage at the time of partial display are slightly higher than at the time of full screen display. However,
When n ≦ 8, both the selection voltage and the non-selection voltage at the time of partial display are substantially the same as those at the time of full-screen display.
S can be displayed on the display unit at the time of partial display even if it is at the time of full screen display.

As n increases, both the selection voltage and the non-selection voltage at the time of partial display become higher. If the display becomes too dark, it is necessary to adjust the voltage so as to lower VC and VS. However, since this voltage adjustment width is much smaller than the method of performing 1 / N duty drive during normal display, but switching to 1 / n duty drive during partial display, the drive voltage range of the driver IC is problematic. No.

Method 3 As shown in FIG. 11, the frame period of the period N · τ is divided into the first period (1 <β ≦ 2, n <N / β) of the first half period n · β · τ. The period is divided into a second period of (N−n · β) · τ. -To the scanning electrodes (COM1 to COMn) of the display unit, the selection potentials of the periods β and τ are applied while sequentially shifting the time during the first period. The non-selection potential is always maintained during the period when the selection potential is not applied.

Scanning electrodes in the non-display area (COM n + 1 to COM n + 1)
COM N) always holds the non-selection potential throughout the frame period. The signal electrodes (SEG1-SEGM) have their signal electrodes and scanning electrodes (COM1-COM) in the first period.
A potential determined in the same manner as in full-screen display is applied in correspondence with the display data of the pixel at the intersection with n) and the selection potential of the scanning electrode. In addition, a scanning electrode non-selection potential is applied in the second period.

As in the case of full-screen display, the polarity of each drive waveform is inverted for each frame to prevent deterioration of the liquid crystal display panel. At this time, the difference between the potentials applied to the scanning electrodes and the signal electrodes, that is, the voltage applied to the display pixels is shown in FIG.
It is shown in FIG. The effective values of the non-selection voltage of the display unit, the selection voltage, and the applied voltage of the non-display unit are VOFF4 and VO, respectively.
Assuming that N4 and VN4, VOFF4 = {β · (VC−VS) ² / N + β · (n−1) · VS ² / N} ^1/2 (Equation 13) VON4 = {β · (VC + VS ) ² / N + β · (n−1) · VS ² / N} ^1/2 (Equation 14) VN4 = VS · (β · n / N) ^1/2 (Equation 15) Method 3 (1) Method 3 When the selection potential of the scan electrode is set to the same value in full screen display and partial display, the value of β is set so that the effective voltage applied to the selected pixel is equal in full screen display and partial display. Decide. VC at partial display and V at full screen display
When C is set to the same value and VS at the time of partial display and VS at the time of full-screen display are set to the same value, the condition for making the selected voltages equal is as follows: VON4 = VON, β = {(VC + VS) ² + (N−1) · VS ² } / {(VC + VS) ² + (n−1) · VS ² } (Equation 16) When N = 240, VC is common in both full screen display and partial display.
= 18.12 (V), VS = 1.17 (V),
Computing each voltage when n = 8, 16, 32, 64, and 120 and comparing full screen display, method 1 (1), and method 3 (1),

[0042]

[Table 4]

According to the method 3 (1), while maintaining the same selection voltage as in full screen display, the non-selection voltage in partial display,
Further, the applied voltage to the non-display portion can be reduced as compared with the method 1 (1). The smaller the value of n, the greater the effect of reducing the applied voltage of the non-display section.
%, The non-selection voltage of the method 3 (1) is about 94% of the non-selection voltage at the time of full screen display. Further, the non-display portion applied voltage of the method 3 (1) is about 25% of the non-display portion applied voltage of the method 1 (1).
Becomes

Method 2 (1) and Method 3 for the same n
Comparing (1), the applied voltage of the non-display part is determined by the method 3
The method 2 (1) is lower than the method (1). On the other hand, the non-selection voltage of the display unit is lower in the method 3 (1) than in the method 2 (1).
That is, the driving margin of the display unit is larger in the method 3 (1) than in the method 2 (1). As described above, method 2 (1),
Alternatively, according to method 3 (1), the same selection voltage as in full screen display can be applied to the display unit even in partial display while VC and VS are kept constant, and the applied voltage in the non-display unit is the same as in method 1 (1).
(1) It can be smaller.

Method 3 (2) In method 3 (1), the values of β for making the same voltage VC and VS and the same selection voltage in partial display and full screen display are shown in Table 4. Is not an integer. Therefore,
The drawback is that the basic clock for creating the display timing must be higher than that for full-screen display, which increases the power in that part and complicates the configuration of the frequency divider circuit for creating the display timing. There is.

Therefore, in order to improve the above-mentioned disadvantage, in method 3 (2), β is fixed to 2 in method 3.
When β is fixed to 2, the period of the selection potential applied to the scanning electrodes is all equal to 2 · τ, so that the frequency of the display timing can be reduced to の of that in full-screen display. N = 240
Thus, VC = 18.1 is common to the full screen display and the partial display.
2 (V), VS = 1.17 (V), n = 8,
Computing each voltage at 16, 32, 64, and 120, and comparing full screen display, method 1 (1), and method 3 (2),

[0047]

[Table 5]

In the case of the method 3 (2), the selection voltage, the non-selection voltage, and the non-display portion applied voltage at the time of partial display are all higher than the method 3 (1). However, when n ≦ 16,
Since the non-selection voltage is lower than in the full-screen display and the selection voltage is higher than in the full-screen display, the display section can be displayed even when VC and VS remain in the full-screen display. Also, for example, n =
In the case of No. 8, the non-display part applied voltage of the method 3 (2) is about 19% of the non-selection voltage in full screen display, and the non-display part applied voltage of the method 3 (2) is the non-display part of the method 1 (1). About 26% of applied voltage
Becomes As n increases, both the selection voltage and the non-selection voltage at the time of partial display increase, so when the display becomes too dark, it is necessary to adjust the voltage so as to lower VC and VS. However, since this voltage adjustment width is much smaller than the method of performing 1 / N duty drive during normal display, but switching to 1 / n duty drive during partial display, the drive voltage range of the driver IC is problematic. No.

(Embodiment 2) In the first embodiment, an example in which the present invention is applied to a case where the full-screen display is line-sequential driving has been described. However, the present invention is not limited to line-sequential driving. The present invention is also applicable to a case where the screen display is a multiple line simultaneous selection drive (MLA drive). The driving method in the partial display is similar to the various methods of the first embodiment even when the full screen display is the MLA drive. Only corresponding examples will be described.

FIG. 13 shows an example of scan electrode drive waveforms and signal electrode drive waveforms when full-screen display is performed by two-line MLA driving. The selection potential of the scanning electrode is + VC or -V
C, the non-selection potential of the scanning electrode is 0 potential. COM 1
, COM2, COM3 and COM4,..., While applying a scan electrode selection potential set in a period τ twice while shifting the time for each set of two scan lines, COM N−1
One scan is completed when the application of up to the set of COMN is completed. The period required for one scan is called a frame period,
N · τ. The polarity of each drive waveform is inverted every frame to prevent deterioration of the liquid crystal display panel. Here, it is generally known that the two applications of the set of the scanning electrode selection potentials in the period τ need not be continuous, and the set of the scanning electrode selection potentials in the period τ may be dispersed in the frame period. ing. In the following, only the case of not dispersing will be described for simplification.

A potential determined as shown in Table 6 is applied to the signal electrode from the correspondence between the display data of the pixel on the scanning electrode to which the scanning electrode selection voltage is applied and the scanning electrode selection potential.
In Table 6, the set of the selection potentials of the two scanning electrodes to which the selection potential is applied simultaneously is (C0, C1), and +1 is + V
C and -1 correspond to -VC. Further, the display data of the pixel on the scanning electrode is (D0, D1),
It is assumed that +1 corresponds to display off and -1 corresponds to display on. Also, let S be the potential applied to the signal electrode at that time,
+1 corresponds to + VS, 0 corresponds to 0 potential, and -1 corresponds to -VS.

[0052]

[Table 6]

In order to prevent the deterioration of the liquid crystal display panel, the polarity of each drive waveform is inverted every frame. FIG. 14 shows the difference between the potentials applied to the scanning electrodes and the signal electrodes at this time, that is, the voltages applied to the display pixels. When the effective value of the voltage applied to the display pixel is expressed by an equation, the non-selection voltage VOF
F * and select voltage VON * each, VOFF * = {(VC- VS) 2 / N + (N / 2-1) · VS 2 / N + VC 2 / N} 1/2 ( number 17) VON * = ^{{(VC + VS) 2 /} N + (N / 2-1) · VS 2 / N + VC 2 / N} 1/2 ( number 18) will now be described various drive method in the partial display.

Method 1 * As shown in FIG. 15, the frame period of the period N · τ is divided into the first period of the first half period n · τ and the second period of the remaining period (N−n) · τ. Separate. The selection potential in the period τ is applied twice to the scan electrodes (COM 1 to COM n) of the display unit while shifting the time for each pair of two scan lines in the first period. The non-selection potential is always maintained during the period when the selection potential is not applied.

Scanning electrode (COM n + 1 to COM n + 1)
COM N) always holds the non-selection potential throughout the frame period. The signal electrodes (SEG1-SEGM) have their signal electrodes and scanning electrodes (COM1-COM) in the first period.
A potential determined in the same manner as in full-screen display is applied in correspondence with the display data of the pixel at the intersection with n) and the selection potential of the scanning electrode. In addition, a predetermined potential is applied in the second period.

As in the case of full-screen display, the polarity of each drive waveform is inverted every frame to prevent deterioration of the liquid crystal display panel. Method 1 * (1) When the selection potential of the scanning electrode is set to the same value in the full screen display and the partial display in the method 1 *, the effective voltage applied to the selected pixel is in the full screen display and the partial display. The potential to be applied to the signal electrode during the second period at the time of partial display is determined so that For this purpose, the potential applied to the signal electrode during the second period during the partial display may be the same as that during the full-screen display, and the display data assumed in the non-display portion at that time is arbitrary. FIG. 15 shows a signal electrode drive waveform in the case where the potential applied during the second period is determined on the assumption that the non-display portion is fully turned off. FIG. 16 shows the difference between the potentials applied to the scanning electrodes and the signal electrodes at this time, that is, the voltages applied to the display pixels.

Here, the potential applied to the signal electrode during the second period during the partial display can be freely determined unless the effective voltage is changed. Therefore, to reduce the power, the potential applied to the signal electrode during the partial display is reduced. It is desirable to select the potential applied in the second period so that the change in potential is as small as possible. As an example, FIG. 17 shows a signal electrode drive waveform when + VC is applied in the first half of the second period and 0 potential is applied in the second half of the second period. Alternatively, the potential may be set as shown in FIG. 18 so that the applied potential becomes 0 at the start and end of the second period. Since the potential difference at the boundary with the first period is suppressed to the maximum VC, the influence of display data on the display unit can be reduced.

At this time, the non-selection voltage of the display unit, the selection voltage, and the effective value of the applied voltage of the non-display unit are represented by V, respectively.
OFF1 *, VON1 *, and when the VN1 *, VOFF1 * = {( VC-VS) 2 / N + (N / 2-1) · VS 2 / N + VC 2 / N} 1/2 ( number 19) VON1 * = {(VC + VS) ² / N + (N / 2-1) ・ VS ² / N + VC ² / N} ^1/2 (Equation 20) VN1 * = VS / 2 ^1/2 (Equation 21) In the 1 * (2) method 1 * (1), during partial display, the polarity of the potential applied to the plurality of signal electrodes in the second period is inverted between half or almost half of the entire signal electrodes and the remaining signal electrodes. . As a result, the charge and discharge currents of the liquid crystal display element cancel each other, so that the power consumption of the drive circuit can be reduced. At this time, the non-selection voltage of the display unit, the selection voltage, and the effective value of the applied voltage of the non-display unit are the same as those in the method 1 * (1).

Method 1 * (3) In method 1 * (1), during partial display, the polarity of the potential applied to the plurality of signal electrodes in the second period is inverted for each adjacent signal electrode. As a result, the charge and discharge currents of the liquid crystal display element cancel each other, so that the power consumption of the drive circuit can be reduced. At this time, the non-selection voltage of the display unit, the selection voltage, and the effective value of the applied voltage of the non-display unit are the same as those in the method 1 * (1).

When N = 240, VC = 12.81 (V) and VS = 1.65 are common to the full screen display and the partial display.
Under the condition of (V), each voltage when n = 8, 16, 32, 64, and 120 is calculated, and full screen display and method 1 *
Comparing (1),

[0061]

[Table 7]

In the method 1 * (1), the non-selection voltage and the selection voltage at the time of partial display are the same as those at the time of full-screen display regardless of n, and the voltage applied to the non-display portion is about 68% of the non-selection voltage. .
Therefore, the display can be performed with the same contrast ratio as in the full-screen display even in the partial display, and the voltage applied to the non-display portion is reduced as compared with the full-screen display. Method 3 * As shown in FIG. 19, the frame period of the period N · τ is divided into the first period (1 <β ≦ 2, n <N / β) of the first half period n · β · τ and the remaining period ( N−n · β) · τ.

Scanning electrodes of the display section (COM 1 to COM
In n), the selection potential of the period β · τ is applied twice while shifting the time for each pair of two scanning lines in the first period. The non-selection potential is always maintained during the period when the selection potential is not applied. -Scan electrode of non-display part (COM n + 1 to COM N)
Keeps the non-selection potential at all times during the entire frame period.

Also, signal electrodes (SEG1-SEG)
M) has its signal electrode and scan electrode (CO
A potential determined as shown in Table 6 is applied from the correspondence between the display data of the pixel at the intersection with M1 to COM n) and the selection potential of the scanning electrode. In addition, a scanning electrode non-selection potential is applied in the second period. As in the case of full screen display, the polarity of each drive waveform is inverted for each frame to prevent deterioration of the liquid crystal display panel.

At this time, the difference between the potentials applied to the scanning electrodes and the signal electrodes, that is, the voltage applied to the display pixels is shown in FIG.
0 is shown. The effective values of the non-selection voltage of the display unit, the selection voltage, and the applied voltage of the non-display unit are represented by VOFF4 * and VOFF4, respectively.
ON4 *, and when the VN4 *, VOFF4 * = {β · (VC-VS) 2 / N + β · (n / 2-1) · VS 2 / N + β · VC 2 / N} 1/2 ( Equation 22) VON4 * = {β · (VC + VS) ² / N + β · (n / 2-1) · VS ² / N + β · VC ² / N} ^1/2 (Equation 23) VN4 * = VS · {β · n / (2N)} ^1/2 (Equation 24) Method 3 * (1) When the selected potential of the scan electrode is set to the same value in full screen display and partial display in method 3 * The value of β is determined so that the effective voltage applied to the selected pixel is equal between the full screen display and the partial display. When VC at the time of partial display and VC at the time of full screen display have the same value, and VS at the time of partial display and VS at the time of full screen display have the same value, the condition for equalizing the selected voltage is VON4 * = VON * β = {(VC + VS) ² + (N / 2-1) · VS ² + VC ² } / {(VC + VS) ² + (n / 2-1) · VS ² + VC ² } (Equation 25) When N = 240, the common VC is used for both full screen display and partial display.
= 12.81 (V), VS = 1.65 (V),
Computing each voltage when n = 8, 16, 32, 64, and 120, and comparing full screen display, method 1 * (1), and method 3 * (1),

[0066]

[Table 8]

As is clear from comparison between Table 8 and Table 4, the correspondence between n and various voltage values is exactly the same. Therefore, according to the method 3 * (1), as in the method 3 (1), when VC and VS are kept constant and the same selection voltage is maintained as in full-screen display, for example, when n = 8 ,
The non-display part applied voltage of method 3 * (1) is about 18% of the non-selection voltage at the time of full screen display, and the non-selection voltage of method 3 * (1) is about 94% of the non-selection voltage at the time of full screen display. Can be reduced. In addition, the non-display portion applied voltage in method 3 * (1) is
This is about 25% of the voltage applied to the non-display section in (1).

Method 3 * (2) In method 3 * (1), VC is used for partial display and full screen display.
And VS are the same voltage, and the value of β for making the selection voltage the same is not an integer as shown in Table 8. Therefore, the basic clock for generating the display timing must be higher in frequency than when displaying the full screen, and the power is increased in that part, and the configuration of the frequency dividing circuit for generating the display timing is slightly complicated. There is a disadvantage that.

Therefore, in order to improve the above-mentioned disadvantage, in method 3 * (2), β = 2 is fixed in method 3 *. When β is fixed to 2, the period of the selection potential applied to the scanning electrodes is all equal to 2 · τ, so that the frequency of the display timing can be reduced to の of that in full-screen display. N = 2
40, VC = 1 for both full screen display and partial display
Under the conditions of 2.81 (V) and VS = 1.65 (V), n
= 8, 16, 32, 64, and 120, and comparing the full screen display with the method 3 * (2),

[0070]

[Table 9]

As is clear from comparison between Table 9 and Table 5, the correspondence between n and various voltage values is exactly the same. Therefore, in the case of method 3 * (2) as in method 3 (2),
When n ≦ 16, the non-selection voltage is lower than that during full-screen display and the selection voltage is higher than during full-screen display.
S can be displayed on the display unit even during full screen display. Further, for example, when n = 8, the non-display portion applied voltage of the method 3 * (2) is about 19% of the non-selection voltage in full screen display,
The applied voltage of the non-display part in the method 3 * (2) is about 26% of the applied voltage of the non-display part in the method 1 * (1).

As n increases, both the selection voltage and the non-selection voltage at the time of partial display increase, so if the display becomes too dark, it is necessary to adjust the voltage so as to lower VC and VS. However, since this voltage adjustment width is much smaller than the method of performing 1 / N duty drive during normal display, but switching to 1 / n duty drive during partial display, the drive voltage range of the driver IC is problematic. No.

Although the two-line MLA drive has been described above, the present invention can be similarly applied to MLAs having more than two lines.

[0074]

As described above, according to the present invention,
At the time of partial display, the scan electrode drive circuit corresponding to the non-display portion can stop the operation for scanning, and during the second period at the time of partial display, transfer of display data to the signal electrode drive circuit and signal electrode drive circuit This eliminates the need to convert the display data to drive output in the LCD, and further reduces the voltage applied to the non-display area from the non-selection voltage during full-screen display, thus reducing the power consumption of the liquid crystal display element drive circuit. It has an excellent effect that it can be performed.

Further, in the partial display method of the present invention, the partial display can be performed at the same scan electrode selection potential as the full screen display or at the scan electrode selection potential close to the full screen display.
Therefore, even when switching between full screen display and partial display is performed by one driver IC, the operating voltage range of the driver IC may be substantially the same as in the case where only full screen display is performed, and the chip area of the IC increases. Does not accompany.
Also, even when switching between full screen display and partial display, there is almost no need to adjust the scanning electrode selection potential. In addition, even if n changes, there is an excellent effect that there is almost no need to change the ratio of the scanning electrode selection potential to the signal electrode potential or the scanning electrode selection potential.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a scan electrode drive waveform and a signal electrode drive waveform during partial display according to the present invention.

FIG. 2 is a diagram illustrating an example of an arrangement of electrodes of a liquid crystal display panel and a full screen display.

FIG. 3 is a diagram showing an example of a partial display according to the present invention.

FIG. 4 is a diagram showing an example of scan electrode drive waveforms and signal electrode drive waveforms when full-screen display is performed by line-sequential driving.

FIG. 5 is a diagram showing a voltage applied to a display pixel in FIG. 4;

FIG. 6 is a diagram showing an example of a scan electrode drive waveform and a signal electrode drive waveform during partial display according to the present invention.

FIG. 7 is a diagram showing a voltage applied to a display pixel in FIG. 6;

FIG. 8 is a diagram showing an example of a scan electrode drive waveform and a signal electrode drive waveform during partial display according to the present invention.

9 is a diagram illustrating a voltage applied to a display pixel in FIG.

FIG. 10 is a diagram showing a voltage applied to a display pixel in FIG.

FIG. 11 is a diagram showing an example of a scan electrode drive waveform and a signal electrode drive waveform during partial display according to the present invention.

12 is a diagram showing a voltage applied to a display pixel in FIG.

FIG. 13 is a diagram showing an example of a scan electrode drive waveform and a signal electrode drive waveform when performing full-screen display by two-line simultaneous selection drive.

FIG. 14 is a diagram showing a voltage applied to a display pixel in FIG.

FIG. 15 is a diagram showing an example of a scan electrode drive waveform and a signal electrode drive waveform during partial display according to the present invention.

16 is a diagram showing a voltage applied to a display pixel in FIG.

FIG. 17 is a diagram showing an example of a scan electrode drive waveform and a signal electrode drive waveform during partial display according to the present invention.

FIG. 18 is a diagram showing an example of a scan electrode drive waveform and a signal electrode drive waveform during partial display according to the present invention.

FIG. 19 is a diagram showing an example of a scan electrode drive waveform and a signal electrode drive waveform during partial display according to the present invention.

20 is a diagram showing a voltage applied to a display pixel in FIG. 19;

[Explanation of symbols]

 21 Non-selected pixel 22 Selected pixel 31 Display unit 32 Non-display unit 33 Non-selected pixel of display unit 34 Selected pixel of display unit 35 Pixel of non-display unit

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[Procedure amendment]

[Submission date] February 15, 1999 (1999.2.1
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

Method 1 (4) In the liquid crystal display element driving method of Method 1, the potential applied to the signal electrode in the second mode in the second period is set as the non-selection potential of the scanning electrode. Method 2 A method for driving a matrix-type liquid crystal display element including N scanning electrodes (N is an integer of 2 or more) and a plurality of signal electrodes has a first mode and a second mode. The selection potential in the period τ is applied L times (L is a natural number) per frame to all the scanning electrodes, and is kept at the non-selection potential during the period in which the selection potential is not applied. A potential determined by the correspondence between the display data of the pixel at the intersection and the selection potential of the scanning electrode is applied.
N scan electrodes (n is an integer such that n <N)
And a second scan electrode group consisting of the remaining (N-n) scan electrodes, and the frame period is divided into a first period and a second period. A selection potential of a period τ is applied to each scanning electrode of one scanning electrode group L times in each frame during a first period, and a non-selection potential is always held during a period when no selection potential is applied in the first period. In the second period, the selection potential in the period of ατ ( 0 <α <N−n ) is applied L times for each frame, and in the second period, the non-selection potential is always held during the period in which the selection potential is not applied. , Each scanning electrode of the second scanning electrode group always holds a non-selection potential over the entire frame period, and the signal electrode has an intersection between the signal electrode and each scanning electrode of the first scanning electrode group in the first period. A potential determined by the correspondence between the display data of the pixel and the selection potential of the scanning electrode, During that time, a non-selection potential of the scanning electrode is applied.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

Method 3 In a method for driving a matrix type liquid crystal display element comprising N scanning electrodes (N is an integer of 2 or more) and a plurality of signal electrodes, the method has a first mode and a second mode, In the mode, the selection potential in the period τ is applied L times (L is a natural number) per frame to all the scanning electrodes, and the non-selection potential is always held during the period in which the selection potential is not applied. A potential determined according to the display data of the pixel at the intersection with the electrode is applied, and in the second mode, N scan electrodes are replaced with a first scan composed of n scan electrodes (n is an integer of n <N). The first scan electrode group is divided into a first scan electrode group and a second scan electrode group including a second scan electrode group including the electrode group and the remaining (N−n) scan electrodes. each scan electrode selection potential period beta · tau in the first period (1 <β <n / n
Is applied L times for each frame, the non-selection potential is always held during the period in which the selection potential is not applied in the first period, the non-selection potential is always held in the second period, and the second scan electrode group Each scan electrode always holds a non-selection potential over the entire frame period, and the signal electrode has display data of the pixel at the intersection of the signal electrode and each scan electrode of the first scan electrode group with the scan electrode during the first period. And a non-selection potential of the scanning electrode is applied in the second period.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

Scanning electrodes of the display section (COM 1 to COM
In n), the selection potential in the period τ is applied while sequentially shifting the time in the first period, and the selection potential (0 <α < N−n ) in the period α · τ is applied in the second period. The non-selection potential is always maintained during the period when the selection potential is not applied.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction contents]

Method 3 As shown in FIG. 11, the frame period of the period N · τ is divided into a first period (1 <β <N / n ) of the first half period n · β · τ and a remaining period (N− n
β) · τ is divided into the second period. -To the scanning electrodes (COM1 to COMn) of the display unit, the selection potentials of the periods β and τ are applied while sequentially shifting the time during the first period. The non-selection potential is always maintained during the period when the selection potential is not applied. -Scan electrode of non-display part (COM n + 1 to COM N)
Keeps the non-selection potential at all times during the entire frame period.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0062

[Correction method] Change

[Correction contents]

In the method 1 * (1), the non-selection voltage and the selection voltage at the time of partial display are the same as those at the time of full-screen display regardless of n, and the voltage applied to the non-display portion is about 68% of the non-selection voltage. .
Therefore, the display can be performed with the same contrast ratio as in the full-screen display even in the partial display, and the voltage applied to the non-display portion is reduced as compared with the full-screen display. Method 3 * As shown in FIG. 19, the frame period of the period N · τ is divided into the first period (1 <β <N / n ) of the first half period n · β · τ and the remaining period (N−n ·
β) · τ is divided into the second period.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/20 622 G09G 3/20 622R 650 650A F-term (Reference) 2H093 NA10 NA20 NA26 NA33 NA79 NC90 ND39 ND49 ND60 NF13 5C006 AA01 AC02 AC23 AC24 AC28 AF34 AF44 AF52 AF71 BB12 BB14 BC03 BC12 EB05 FA05 FA16 FA47 FA51 5C080 AA10 BB05 DD25 DD26 EE32 FF12 JJ04

Claims (14)

[Claims] 1. A method for driving a matrix-type liquid crystal display device comprising N scanning electrodes, where N is an integer of 2 or more, and a plurality of signal electrodes, comprising: a first mode and a second mode; In the first mode, the selection potential in the period τ is applied L times to all the scanning electrodes every frame, where L is a natural number, and
A period in which the selection potential is not applied is always maintained at a non-selection potential, and a potential obtained from display data of a pixel at an intersection of the signal electrode and the scanning electrode and a selection potential of the scanning electrode is applied to the signal electrode; In the second mode, N scan electrodes are replaced with n scan electrodes, where n is an integer satisfying n <N, and a second scan electrode group including the remaining (N−n) scan electrodes. And the frame period is divided into a first period and a second period, and each scan electrode of the first scan electrode group is supplied with a selection potential in a period τ during the first period. The voltage is applied L times per frame, and the non-selection potential is always held during a period when the selection potential is not applied in the first period, and the non-selection potential is always held during the second period. Each scan electrode in the group always has a non-selection potential throughout the frame period. Applying a potential determined from display data of a pixel at an intersection of the signal electrode and each scanning electrode of the first scanning electrode group and a selection potential of the scanning electrode to the signal electrode during a first period, A method for driving a liquid crystal display element, wherein a predetermined potential determined in advance is applied in a second period. 2. The method for driving a liquid crystal display element according to claim 1, wherein the selection potential of the scanning electrode is applied to the selected pixel when the same potential is set in the first mode and the second mode. Determining a potential applied to the signal electrode during the second period in the second mode so that an effective voltage to be applied is equal between the first mode and the second mode. A method for driving a display element. 3. The method of driving a liquid crystal display element according to claim 1, wherein the polarity of the potential applied to the plurality of signal electrodes in the second mode in the second period is half of the total. Alternatively, a method of driving a liquid crystal display element, wherein the inversion is performed by almost half of the signal electrodes and the remaining signal electrodes. 4. The method for driving a liquid crystal display element according to claim 1, wherein the polarity of a potential applied to the plurality of signal electrodes in the second mode in the second period is adjacent to the signal electrodes. A method for driving a liquid crystal display element, wherein the method is reversed for each electrode. 5. The method of driving a liquid crystal display element according to claim 1, wherein a potential applied to the signal electrode in the second period in the second mode is a non-selection potential of the scanning electrode. Driving method of the liquid crystal display element. 6. A method of driving a matrix-type liquid crystal display element comprising N scanning electrodes, where N is an integer of 2 or more, and a plurality of signal electrodes, wherein the driving method has a first mode and a second mode, In the first mode, the selection potential in the period τ is applied L times to all the scanning electrodes per frame, where L is a natural number, and is always kept at the non-selection potential during the period in which the selection potential is not applied. A display data of a pixel at an intersection of the signal electrode and the scanning electrode and a potential determined from a selection potential of the scanning electrode are applied. In the second mode, the N scanning electrodes are replaced with n scanning electrodes, where n is a scanning electrode. Is divided into a first scan electrode group consisting of n <N, and a second scan electrode group consisting of the remaining (N−n) scan electrodes, and the frame period is divided into a first period and a first period. Each scan of the first scan electrode group The electrode is applied with the selection potential for a period τ L times per frame during the first period, and during the period in which the selection potential is not applied in the first period, the non-selection potential is always held. Where a selection potential of 0 <α ≦ 1 is applied L times for each frame, and a non-selection potential is always held during a period in which the selection potential is not applied in the second period. Each scanning electrode of the second scanning electrode group always holds a non-selection potential over the entire frame period, and the signal electrode includes a signal electrode and a scanning electrode of the first scanning electrode group during the first period. A method for driving a liquid crystal display element, wherein a potential determined from display data of a pixel at an intersection and a selection potential of a scanning electrode is applied, and a non-selection potential of a scanning electrode is applied during the second period. 7. The method of driving a liquid crystal display element according to claim 6, wherein the selection potential of the scanning electrode is applied to the selected pixel when the same potential is set in the first mode and the second mode. A method of driving the liquid crystal display element, wherein the value of α is selected so that the effective voltage to be applied is equal between the first mode and the second mode. 8. The method for driving a liquid crystal display device according to claim 6, wherein α = 1. 9. A method for driving a matrix-type liquid crystal display device comprising N scanning electrodes, where N is an integer of 2 or more, and a plurality of signal electrodes, the method comprising: a first mode and a second mode; In the first mode, the selection potential in the period τ is applied to all the scanning electrodes L times per frame, where L is a natural number, and is always kept at the non-selection potential during the period in which the selection potential is not applied. Applying a potential determined from the display data of the pixel at the intersection of the signal electrode and the scan electrode; and in the second mode, the N scan electrodes are replaced by n scan electrodes,
n is divided into a first scan electrode group consisting of n <N and an second scan electrode group consisting of the remaining (N−n) scan electrodes, and the frame period is defined as a first period. Divided into a second period, each scanning electrode of the first scanning electrode group has a selection potential in a period β · τ during the first period, provided that 1 <β ≦ 2 and n <
N / β is applied L times for each frame, a non-selection potential is always held during a period in which the selection potential is not applied in the first period, and a non-selection potential is always held in the second period. Each scan electrode of the second scan electrode group always holds a non-selection potential over the entire frame period, and the signal electrode has an intersection of a signal electrode and each scan electrode of the first scan electrode group in a first period. A method for driving a liquid crystal display element, comprising applying a potential determined from display data of a pixel and a selection potential of a scanning electrode, and applying a non-selection potential of a scanning electrode during the second period. 10. The method of driving a liquid crystal display element according to claim 9, wherein the selection potential of the scanning electrode is set to the same value in the first mode and the second mode, and is applied to the selected pixel. Wherein the value of β is selected so that the effective voltage becomes equal in the first mode and the second mode. 11. The method of driving a liquid crystal display device according to claim 9, wherein β = 2. 12. The method of driving a liquid crystal display device according to claim 1, wherein the driving is performed for a plurality of lines simultaneously. 13. The display according to claim 1, wherein the first mode and the second mode are switched and displayed as needed.
13. A method for driving a liquid crystal display device according to claim 12. 14. A method for driving a matrix-type liquid crystal display element comprising N scan electrodes, where N is an integer of 2 or more, and a plurality of signal electrodes, wherein the N scan electrodes are n scan electrodes, Where n is n <
A first scan electrode group consisting of an integer N and the remaining (N−
n) dividing into a second scan electrode group consisting of scan electrodes;
Further, the frame period is divided into a first period and a second period, and a selection potential of a period τ is applied L times to each scan electrode of the first scan electrode group in each frame during the first period. In the first period, the non-selection potential is maintained during the period in which the selection potential is not applied, and the non-selection potential is maintained during the second period. Each scan electrode of the second scan electrode group is connected during a frame period. A non-selection potential is applied to the signal electrode, and a potential obtained from display data of a pixel at an intersection of the signal electrode and each scanning electrode of the first scanning electrode group and a selection potential of the scanning electrode is applied to the signal electrode during the first period. And applying a potential during the second period.