JP2001228835A - Drive method for display device, display device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive method which sets a screen into display conditions and nondisplay conditions which using a fixed power source without changing duty. SOLUTION: In the driving method for a display device provided with plural display elements (liquid crystals), a drive circuit for scanning lines and a drive circuit for data lines, the voltage level of the scanning lines during a nonselecting condition is only one. Display control signals are inputted to the drive circuit for the scanning lines, and an area served by continuous K pieces of lines from among N pieces lines (where K is an integer which is smaller than N and larger than >=2) is defined as an area of nondisplay conditions and an area served by other scanning lines is defined as an image displaying area. No selection voltage is applied to the K pieces of scanning lines, and the lines are held at a nonselecting voltage level. During the period when the K pieces of scanning lines are originally selected, the voltages to be applied for display is applied to the data lines. Since no duty is changed as compared to a full display, variable power source is dispensed with.

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 display device, a display device, and an electronic apparatus, and more particularly to a technique for reducing power consumption of the display device.

[0002]

2. Description of the Related Art A simple matrix type liquid crystal display device is inexpensive because it does not require expensive switching elements on a substrate as compared with an active matrix type liquid crystal display device. Therefore, a monitor of a portable computer, a portable electronic device, etc. Widely used for

The following is known as a method of driving this simple matrix type liquid crystal display device.

The APT method (IEEE TRANSACTIONS OF ELECT)
RON DEVICE, VOL, ED-21, No2, FEBRUARY 1974 P146-15
5 "SCANNING LIMITATIONS OF LIQUID-CRYSTAL DISPLAYS"
P.ALT, P.PLESHKO, ALT & PLESHKO TECHNIC).

[0005] Smart Addressing (LCD International '
95, LCD display seminar sponsored by Nikkei BP,
C-4 Lecture number (1), Sanyo Tottori Electric, Mr. Matsushita).

A multi-line driving method (for example, Japanese Patent Application No. 4-84007, Japanese Patent Application Laid-Open No. 5-46127),
JP-A-6-130910).

[0007]

In recent years, in the field of portable electronic devices such as cellular phones and pagers, there has been an increasing demand for not only a reduction in size and weight but also an extension of the display time without replacing batteries. I have. Therefore, a display device mounted on a portable electronic device is required to have low power consumption.

The present inventor has conducted various studies on a simple matrix type liquid crystal display device from the viewpoint of reducing power consumption.

As a result, in the conventional simple matrix type liquid crystal display device, an AC waveform having an amplitude of 20 V or more must be supplied to each of the scanning lines and the signal lines even in the display off state. It was found that the power consumption of the voltage source circuit was large, and the current flowing between the scanning line and the data line via the liquid crystal was large.

The present invention has been made in order to solve such problems.

[0011]

SUMMARY OF THE INVENTION One of the main objects of the present invention is to reduce the power consumption of a display device such as a simple matrix type liquid crystal display device.

In a preferred embodiment of the display device driving method according to the present invention, when the voltage level of the scanning line is only one at the time of non-selection, and when the display element is in the non-display state, it corresponds to the display element. The voltage level of the data line is the voltage level when the scanning line is not selected.

According to this driving method, even if a driving method of displaying an image by periodically inverting the polarity of the selection voltage applied to the scanning line is adopted, regardless of the polarity of the selection voltage of the scanning line. , Non-selection voltage levels are always the same (one). Therefore, the non-display state can be easily realized by setting the voltage level of the data line to the non-selection voltage level of the scanning line.

Here, the non-display state means a display off state. The screen in the display off state is a screen in the display off mode. The display-off mode is a mode for realizing extremely low power consumption. In the following description, the expressions “display-off state”, “display-off mode”, and “screen in display-off mode” are mainly used.

In the present invention, if the scanning lines are set to the non-selection voltage and the data lines are set to the same voltage, the voltage difference between the two lines disappears and the display is turned off (display off mode).

Since there is one non-selection voltage level, the configuration of the voltage source circuit for generating the non-selection voltage is simplified,
Power consumption in the voltage source circuit is reduced. Also,
Compared with the case where the non-selection voltage is periodically changed, it becomes easier to match the data line voltage with the scan line voltage, and power consumption in the display panel due to the potential difference between the scan line and the data line is reduced. Therefore, power consumption of the display device is reduced.

Further, even if a selection pulse is input to the scanning line while the voltage level of the data line is maintained at the non-selection voltage level of the scanning line, the display off state is maintained. This is because only the selection of the scanning line during the selection period does not exceed the threshold value of the liquid crystal, and no display is performed.

By utilizing this fact, by appropriately controlling the voltage applied to the data lines, one area of one screen is set to a display off mode, and a predetermined display such as an icon is displayed in another area. It is possible to do.

In a preferred embodiment of the present invention, a display control signal is input to each of a plurality of ICs for driving data lines, and at least a part of the data line driving output of each IC is input by the display control signal. , The voltage level when the scanning line is not selected.

A plurality of ICs are prepared as data line drivers, and the data line drive output is fixed to a voltage level when a scanning line is not selected in units of each IC. Therefore, the area assigned to the IC can be set to the display off state (display off mode).

In a preferred aspect of the present invention, at least a part of the output for driving the data line is set to a voltage level when the scanning line is not selected, and the display data or the transfer clock for the display data is selected. Of at least one of the ICs is also stopped.

By stopping the transmission of the display data in the display-off state area (the area in the display-off mode) and the high-frequency clock used for transferring the display data, it is possible to further reduce the power consumption.

In a preferred aspect of the present invention, a display control signal is input to a data line drive circuit, and each of the data line drive outputs is individually controlled by the display control signal.
A desired drive output is selectively set to a voltage level when a scanning line is not selected.

Thus, the area in which the display is turned off can be freely set.

In a preferred embodiment of the present invention, the data line drive circuit is constituted by a plurality of blocks, a display control signal is input to the data line drive circuit, and the data is supplied in block units by the display control signal. The line drive output is controlled to set the data line drive output of the corresponding block to the voltage level when the scanning line is not selected.

Thus, it is possible to freely set an area where the display is turned off in units of blocks.

In a preferred aspect of the present invention, h scanning lines (h is an integer of 2 or more) are simultaneously selected from a plurality of scanning lines, and a predetermined selection voltage pattern is applied to each of the scanning lines. And applying a voltage determined based on a comparison between the selected voltage pattern and display data indicating a display state of the display element to each of the data lines to perform a desired display. In the case where the image display is not performed (screen in the image off mode), at least a part of the data line driving output is changed to the voltage when the scanning line is not selected by the display control signal input to the data line driving circuit. Level.

The above-described driving method for realizing the display-off state (screen in the display-off mode) is applied to a display device employing so-called multi-line driving.

In this case, when displaying an image, the power consumption can be reduced by the effect of the multi-line driving method in which the level of the selection voltage applied to the scanning line can be reduced, and the power consumption can be reduced when the display is off. Together with the effect, the power consumption can be further reduced.

In a preferred embodiment of the present invention, the number h of the simultaneously selected scanning lines in the multi-line driving is an even number.

When the number of simultaneously selected scanning lines is "h", the number of voltage levels of the data lines is always "h + 1".
If h is an even number, “h + 1” is an odd number,
Therefore, as for the voltage level of the data line, an even number of voltage levels symmetrical on both the positive and negative sides with respect to the “predetermined reference voltage level” are always set. This “predetermined reference voltage level” can be made to coincide with the non-selected scanning voltage level. That is, when the number of simultaneously selected scanning lines is an even number, the voltage level located at the center among the voltage levels of the data lines can be made to match the voltage level when the scanning line is not selected. Therefore, in order to realize the display off state,
It is not necessary to newly set a voltage level when the scanning line is not selected as the voltage level of the data line. Therefore, the design is easy, the circuit is not complicated, and it is advantageous for low power consumption.

In a preferred embodiment of the present invention, the number h of simultaneously selected scanning lines in multi-line driving is
2, 4, 6, or 8.

When the number of simultaneously selected scanning lines is increased,
The scale of a circuit for realizing the driving is increased, which contradicts the demand for low power consumption. Therefore, the number h of the simultaneously selected scanning lines is 2, 4, 6, 8
Is realistic.

Further, in the display device of the present invention, the above-described driving method is adopted, a voltage at the time of non-selection is applied to a desired data line, and thereby an area to be in a display off state (display off mode is set). Area) can be set freely.

In a preferred embodiment of the display device of the present invention, the display control data and the display data are decoded to specify an area where the display is turned off in units of data lines, or to specify a plurality of display control signals. By the combination, for example, an area in which the display is turned off is specified in a predetermined block unit.

In a preferred aspect of the display device of the present invention, the size of the displayable area is made smaller than the size of the display-off area (the area in the display-off mode), for example, to reduce unnecessary areas during standby. Try to reduce power consumption.

In a preferred aspect of the display device of the present invention, the display device has a portion that covers at least a part of the screen, and an area covered by the portion is an area where the display is turned off.

The area in the display-off state is intended to be invisible to the user. The portion covering at least a part of the screen can be constituted by one or a plurality of movable members, for example, a sliding cover. Further, all or a part of the screen may be stored in the main body according to the use state.

The electronic apparatus of the present invention is an electronic apparatus equipped with a display device capable of appropriately designating the above-mentioned display-off area.

In a preferred embodiment of the present invention, N (N
Is an integer of 2 or more), M (M is an integer of 2 or more) data lines, and a plurality of display states controlled by a voltage applied to the scanning lines and a voltage applied to the data lines. A display element, a scanning line driving circuit, and a data line driving circuit, a driving method of a display device, comprising: inputting a display control signal to the scanning line driving circuit, by the display control signal, Consecutive K of N scanning lines
(K is an integer of 2 or more smaller than N) is excluded from selection targets, and only (N−K) scan lines are displayed as selection targets, and (N−K) scan lines are displayed as selection targets. -K) When driving the scanning lines, the voltage level at the time of selecting the scanning lines is set lower than when driving the N scanning lines.

The boundary position of the area to be set to the display off state is
When appropriately determining the arrangement direction (Y direction) of the scanning lines, the K scanning lines that are in charge of the area where no display is performed are excluded from selection. As a result, the duty (the number of driving scanning lines) in driving the display device changes, and accordingly, the selection voltage level of the scanning lines capable of performing appropriate display decreases. Power consumption can be reduced by lowering the selection voltage level.

The change of the voltage level at the time of selecting the scanning line can be performed by changing the level of the voltage supplied from the variable voltage source to the scanning line driving circuit by the display control signal. The variable voltage source can be configured using a bootstrap circuit.

In a preferred embodiment of the present invention, when displaying an image using the multi-line driving method, the resolution of the displayed image is converted.

In the resolution conversion, when the resolution 1 / Q (Q is an integer of 2 or more) is specified by the resolution conversion signal,
This is performed by applying the same scanning voltage to consecutive Q scanning lines, thereby simultaneously selecting (Q × h) scanning lines. The resolution 1 / Q means that the image size is increased by a factor of Q without changing the duty in driving the display device. In this case, although the power consumption is almost the same, there is an effect that the power of appealing to the user's vision increases because the image is enlarged.

In a preferred embodiment of the present invention, N (N is an integer of 2 or more) scanning lines, M (M is an integer of 2 or more) data lines, a voltage applied to the scanning lines, When driving a display device including a plurality of display elements whose display state is controlled by a voltage applied to a data line, a driving circuit for a scanning line, and a driving circuit for a data line, the scanning at the time of non-selection is performed. The line voltage level is only one, and a display control signal is input to the scan line drive circuit,
According to the display control signal, an area in which continuous K lines (K is an integer of 2 or more smaller than N) of the N scanning lines is an area where no display is performed, and an area in which other scanning lines are in charge. Is a displayable area, the K scanning lines are kept at the non-selected voltage level without applying the selection voltage, and the K scanning lines are to be originally selected during the period to be selected. Applies a voltage to be applied to the data line when performing display.

The boundary position of the area to be set to the display off state is
When appropriately determining the arrangement direction (Y direction) of the scanning lines, the driving duty is not changed for the K scanning lines that are in charge of the area to be in the display-off state. During the period corresponding to the area where the display is in the off state, the voltage is supplied not for the voltage when the scanning line is not selected but for the voltage level for displaying. In order not to change the drive duty,
There is no need to change the selection voltage level of the scanning line. Therefore, the configuration of the voltage source circuit does not become complicated. The present driving method can be applied to a case where a driving method for simultaneously selecting a plurality of scanning lines is adopted.

In a preferred embodiment of the display device of the present invention, the above-described various driving methods are employed, for example, in a standby state, an area other than the minimum necessary display area is displayed in an area in a display off state (display area). Off mode screen) to reduce power consumption.

In a preferred embodiment of the display device of the present invention, a plurality of switch means are provided in a voltage application path to the scanning line or the data line, and when no image is displayed, the switch means is opened to perform scanning. The line or the data line is set in a floating state in terms of potential.

In this case, the path connecting the scanning line, the electro-optical element such as liquid crystal between the scanning line and the data line, and the data line is completely disconnected from the voltage source. Therefore,
There is no danger of unnecessary current flowing through the electro-optical element. However, the scanning line and the data line are unstable in terms of potential,
Since an undesired screen may be formed due to static electricity or the like, it is desirable to cover the entire surface of the display panel with a cover or the like so that the user does not feel uncomfortable.

In a preferred embodiment of the display device of the present invention, at least two display panels are provided, and the driving duty of one panel is appropriately set to select a scanning line and apply a voltage to a data line. The voltage level to be applied. This simplifies the configuration of the voltage source circuit.

In a preferred embodiment of the display device of the present invention, the drive circuit for driving the display matrix has both a function for driving the scanning lines and a function for driving the data lines. .

In this case, by appropriately switching the function according to the shape and size of the image display area and changing the drive duty, the voltage at the time of selecting a scanning line can be reduced, and the power consumption during image display can be reduced. Can be reduced.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments of the present invention, the contents of a study of the prior art made by the present inventors before the present invention will be described.

(1) Investigation Made by the Inventor As shown in FIG. 44, the simple matrix type liquid crystal display device has a first substrate having a plurality of scanning lines Y1 to Yn and a plurality of data lines X1 to Xm. A liquid crystal is sealed between the substrate and a second substrate, and a Y driver (scanning line driving circuit) 4000 and an X driver
A driver (data line driving circuit) 5000 drives each scanning line and each data line, and controls a display state of a pixel (display element) located at an intersection of the scanning line and the data line to perform a desired display.

FIG. 45 shows voltage levels of scanning lines and data lines of a conventional liquid crystal display device.

The left side of FIG. 45 shows the voltage level of the scanning line, and the right side shows the voltage level of the data line.

When the scanning line is selected, two positive and negative levels of V _A6 and V _A1 are prepared, and when the scanning line is not selected, two positive and negative levels of V _A5 and V _A2 are also prepared. . On the other hand, with respect to the voltage level of the data line, and two voltage levels V _A4, V _A6 of positive, two voltage levels of the negative side V _A1, V _A3 are prepared. The voltage levels of the positive side and the negative side are prepared. In a liquid crystal display device, in order to prevent deterioration of the liquid crystal due to application of a DC voltage, etc.
This is because it is necessary to periodically invert the polarity of the voltage applied to the scanning line or the data line.

FIG. 46 shows driving waveforms of the simple matrix type liquid crystal display device. The upper side is the driving waveform of the scanning line, and the lower side is the driving waveform of the data line. The period from the time t1 to the time t2 and the period from the time t4 to the time t5 are the ON period of the pixel, and the period from the time t2 to the time t3 and the period after the time t5 are the OFF period of the pixel.

Focusing on the off period of the pixel, in order to realize a state in which no image is displayed, it is necessary to periodically invert the driving voltages of the scanning lines and the signal lines, and the amplitude thereof is as high as 20 V or more. is there.

For example, a driving method in which the polarity of the driving voltage is inverted for each scanning line is adopted, and as shown in FIG. 47, an area "A" specified by the data line Y1 and the scanning lines X1, X2, X3, and X4. , An area "B" specified by the data lines Y2, Y3, and Y4 and the scanning lines X1, X2, X3, and X4 is set to a state in which no image is displayed. In FIG.
“+” And “−” indicate the polarity of the drive pulse.

In order to turn off the display of the area "B", the data lines Y2 and Y2 are set in accordance with the polarity of the driving pulse of the scanning line.
It can be seen that the polarities of the driving pulses Y3 and Y4 must be inverted for each scanning line. Therefore, the configuration of the voltage source circuit for generating the driving waveform is complicated, and the power consumption is large. In addition, since the data line voltage and the scanning line voltage are constantly fluctuating, the potential difference between the scanning line and the data line is caused. The current flowing through the liquid crystal cannot be ignored, and the power consumption in the display panel is large.

(2) First Embodiment In order to solve the above-mentioned problems, the driving method of the present invention employs:
When the drive voltage levels of the scanning lines and the data lines as shown in FIGS. 1A and 1B are prepared, and as shown in FIG. The voltage levels of both lines are fixed at Vc.

In the display-off state (display-off mode), the voltage levels of the scanning lines and the data lines are always fixed to Vc regardless of the polarity of the driving voltage of the scanning lines and the data lines. It is simplified and power consumption can be reduced. Further, theoretically, since there is no potential difference between the scanning line and the data line, no useless current flows in the display panel.

The voltage levels in FIGS. 1A and 1B will be described more specifically.

FIG. 1A shows a driving voltage level when the present invention is applied to a normal driving method (ATP method) for selecting one scanning line at a time, and the left side shows the scanning line voltage level. The right side is the voltage level of the data line.

The voltage level when the scanning line is selected is V _MX1 ,-
V _MX1 , and the voltage level when not selected is only Vc. On the other hand, the voltage levels of the data lines are V _MY1 , V _MY2 and Vc. Vc is, for example, a ground level.

FIG. 1B shows a driving voltage level of a so-called multi-line driving method for simultaneously selecting a plurality of scanning lines (in FIG. 1B, selecting four lines simultaneously), and the left side shows the scanning line voltage level. The right side is the voltage level of the data line. The voltage level when the scanning line is selected is V _X1 , −V _X1
And the voltage level of the scanning line at the time of non-selection is only Vc. On the other hand, the voltage level of the data line is V _Y1 ,
_VY2 , Vc, _VY4 , and _VY5 .

Next, the configuration of FIG. 2 will be specifically described.

In FIG. 2, X driver 2 is connected to data line D
1, D2, D3, and D4, and the Y driver 4 drives the scanning lines S1, S2, and S3. The pixels are arranged at the intersections of the scanning lines and the data lines to form the liquid crystal panel 6.

For example, suppose that the liquid crystal panel 6 is used for a mobile phone, and an image is displayed on the liquid crystal panel 6 only during a call, and no display is performed during standby. When the mobile phone is in the standby mode, by setting the level of the display control signal DOFF to active (for example, L), the X driver 2
And all the drive outputs of the Y driver 4 are fixed to Vc. Thus, a display-off state with extremely low power consumption is realized.

It should be noted that, even if the Y driver 4 selects a scanning line by applying a driving pulse to each scanning line or a plurality of scanning lines as usual, all outputs of the Y driver are fixed to Vc. As described above, the display off state is maintained. That is, the liquid crystal has a predetermined threshold voltage (V
th) does not cause a change in transmittance unless it exceeds
This is because, simply by inputting a selection pulse to the scanning line at the time of selection, the threshold voltage is not exceeded as long as the data line voltage is at Vc.

By utilizing this fact, by appropriately controlling the voltage applied to each data line, not only the entire liquid crystal panel 6 is turned off as shown in FIG. Can be turned off (partial display off). The implementation of the partial display-off state will be described in detail in the following embodiment.

(3) Second Embodiment FIG. 3A shows a configuration of a liquid crystal display device according to a second embodiment of the present invention, and FIG. 3B shows a mode of display control in the device of FIG. 3A.

This embodiment is characterized in that the data line X160
The screen is divided vertically with a boundary as shown in FIG. 3B,
The area 80 is used as an image display area, and the area 90 is used as an area not used for image display (display-off area), and the screen is divided by controlling the output of a plurality of data line driving ICs. It is.

In FIG. 2, the entire display panel is in a display-off state (display-off screen). However, for example, even when the mobile phone is in a standby state, a display indicating how long a call can be made and a minimum indicating the volume of a speaker or the like are displayed. You may want to display the limit. In this case, if only the area for performing the minimum display is secured and the other areas are set to the display-off mode (display-off state), the power consumption can be minimized.

In FIG. 3A, reference numerals 10, 20, 3
Reference numerals 0 and 40 denote data line driving ICs, each of which has 160
Responsible for driving the data lines. D as a display control signal
OFF (Display Off) 1 and DOFF 2 are prepared, and DOFF 1 is input to the data line driving IC 10,
DOFF2 is commonly input to the data line driving ICs 20, 30, and 40.

Both the display control signals DOFF1 and DOFF2 are active at the low level. At this time, the driving outputs of the data line driving IC are all shown in FIGS. 1A and 1B.
(The voltage level when the scanning line is not selected). Reference numerals 50 and 60 are scanning line driving ICs, each of which is responsible for driving 120 scanning lines.

DOFF1 is “H”, DOFF2 is “L”
Then, the driving output of the data line driving ICs 20, 30, and 40 (the driving output of the data lines X160 to X640) is Vc
Fixed to Thus, as shown in FIG. 3B, the area 90 of the screen of the liquid crystal panel 70 is in a display off state (display off mode).

On the other hand, the data line driving IC 10 sends a driving output for displaying a desired image to the data lines X1 to X160. Further, the scanning line driving ICs 50, 6
A value of 0, for example, sequentially selects scanning lines one by one.
Thereby, as shown in FIG. 3B, a predetermined display is made in area 80 of liquid crystal panel 70.

On the other hand, the area 90 is always in the display-off state. When the scanning line is selected, the selection voltage is applied, but when the scanning line is not selected, both the scanning line and the data line are maintained at Vc. Therefore, useless current does not flow through the liquid crystal, and the power consumption of the liquid crystal panel 70 itself is reduced.

As in the first embodiment, it is not necessary to switch the polarity of the control voltage for turning off the display in accordance with the polarity of the liquid crystal drive. The configuration is also simplified, and the power consumption in the voltage source circuit is significantly reduced.

Note that only a part of the output of one IC may be controlled by the display control signal DOFF.

(4) Third Embodiment In the liquid crystal display device shown in FIG. 4A, two drivers 100 and 110 are provided as data line drivers (X drivers) of the liquid crystal panel 70. The scanning line driver (Y driver) 20 is, for example, a type of driver that selects one scanning line at a time. Note that reference numeral 13 in FIG.
0 is an OR gate.

In this embodiment, four display control signals D
By preparing OFF0, DOFF1, DOFF2, and DOFF3 and controlling the voltage level of each control signal, FIG.
As shown in (5), the area to be set to the display off state can be appropriately selected.

That is, as shown in FIG.
When all the display areas of 0 are “A”, when only DOFF0 is “L”, only the area “B” is in the display off state. When two of DOFF0 and DOFF1 become “L”, the area “B” and the area “C” are turned off, and when DOFF0 to DOFF3 become “L”, the areas “B”, “C” and “ D ”is in the display off state, and when DOFF0 to DOFF3 are all“ L ”, the entire screen of the liquid crystal panel 70 including the area“ E ”is in the display off state.

(5) Fourth Embodiment In response to setting a partial area of the display panel to the display-off mode, display data (image data indicating display-off) relating to the area and transfer of the image data are performed. By stopping the clock for use, the power consumption of the display device can be further reduced. Hereinafter, a circuit configuration for realizing such an operation will be described.

FIG. 7A shows a main configuration of a data line driving circuit of a liquid crystal panel. This data line driving circuit is used for a driving method of selecting one scanning line at a time, and has three voltage levels (V _MY1 , Vc) as shown on the right side of FIG. 5 (FIG. 1A). , V _MY2 ) to the data line.

The circuit shown in FIG. 7A includes an operation timing controller 200, a data shift register 210 for temporarily storing data for driving a data line, a latch 220, a level shifter 230, and three voltage levels (V _MY1 , V _MY) .
c, V _MY2 )
40. Reference numeral 250 is a liquid crystal panel.

In FIG. 7A, XSCL indicates a clock for transferring data for driving the data line, LP indicates a pulse corresponding to a selection pulse, YD indicates a signal indicating the start of one frame period, and DATA indicates a data. Line driving data, and DOFF is a display control signal.

As shown in FIG. 7B, when the display control signal DOFF becomes "L" at time t1, the output of the voltage selector 240 is fixed to Vc, and the corresponding area of the liquid crystal panel 250 is in the display off mode.

At this time, if the data line driving data (DATA) and the transfer clock (XSCL) supplied to the operation timing controller 200 shown in FIG. Can be prevented. Note that stopping only one of the data and the clock has the effect of reducing power consumption. In particular, the transfer clock is a high-frequency signal, and stopping this clock has a great effect.

The stop of the data and the transfer clock is performed, for example, under the control of a microcomputer that controls the operation of the liquid crystal display device in a comprehensive manner.

FIG. 8A is a timing chart showing an operation when both data and clock are stopped in correspondence with the start of the display off mode. In FIG. 8A, FIG.
A, two control signals (DOFF1, DOF
By F2), it is assumed that a part of the area of the liquid crystal panel is partially set to the display off mode.

As shown in FIG. 8A, DOFF1 is "H", DO
When the FF2 is "L", data for 40 transfer clocks is supplied, but the subsequent data transfer (and clock supply) is stopped.

As shown in FIG. 8B, DOFF1, DOF
When both F2 are set to "H", the partial display off mode is released, and the suspension of data and clock is also released.

(6) Fifth Embodiment In this embodiment, the start position of the area in the display-off mode is set freely.

FIG. 9 shows an example of a main configuration of a data line driver (X driver) for performing such display control. The circuit configuration is almost the same as that of FIG. 7A, except that a shift register having the same number of stages as the number of drive outputs for temporarily storing display control data (DOFF) for each drive output is provided. AD2 ... ADm
That is,

AND gates AD1, AD2... ADm
Are provided corresponding to the respective drive outputs, and have a function of performing an AND operation on the data line drive data (DATA) and the display control data (DOFF).

When the display control data (DOFF) is "L", the output of the AND gate is fixed to a predetermined value, and the data of the fixed value is stored in the latch 220. When there is the data of the fixed value, the voltage selector 240 fixes the drive output level corresponding to the data to Vc described above.
Thus, the start position of the area in the display-off mode can be freely set in units of each drive output.

FIGS. 10A and 10B show the display control signal DO.
A timing chart showing an example in which the level of the FF 2 is changed at an appropriate timing, data transfer and clock supply are stopped correspondingly, and the display-off mode area is freely set.

(7) Sixth Embodiment FIG. 1 shows another method of determining an area to be in a display-off mode.
1 to 15 are shown.

As shown in FIG. 11, by combining the voltage levels of the four display control signals DOFF1 to DOFF4,
As shown in FIG. 12A to FIG.
It is possible to set an area where the display-off mode is set during zero. 12A to 12C, the hatched area is the area in the display off mode.

FIG. 13 is a diagram showing an example of a specific configuration of the X driver 280 of FIG.

The four decoders 300, 310, 320,
330 are provided, and the display control signals DOFF1 to DOFF
4 is input to each decoder.

FIG. 14 is a diagram showing another example of the specific configuration of the X driver.

In this example, the decoder (DOFF POSITION DE
CORDER) 400, the display control signals DOFF1 to DO
The FF4 is decoded and each of the decoders 300, 310, 3
20, 330 control signals DX1 to DX4 are created.

A decoder (DOFF POSITION DECORDER) 40
0 indicates, for example, two OR circuits 4 as shown in FIG.
It has a circuit configuration using 10, 412.

(8) Seventh Embodiment When the method of creating a display-off mode screen described in the first embodiment is applied to a so-called multi-line driving method (MLS driving method), the characteristics of the MLS driving method are as follows. Combined with the effect of lowering the voltage level applied to a certain scanning line, the power consumption of the liquid crystal display device can be further reduced. Also, display quality is improved.

The method of creating the display-off mode screen described in the first embodiment is based on the so-called multi-line driving method (ML).
When the present invention is applied to the (S driving method), it is desirable that the number L of the simultaneously selected scanning lines is an even number, and it is more preferable that L is set to any one of 2, 4, 6, and 8. Good. Hereinafter, the reason will be described. The outline of the multi-line driving method will be described later.

As shown in FIG. 16B, when the number of simultaneously selected scanning lines is “L”, the number of voltage levels of the data lines is always “L + 1”. When "L" is an even number, "L + 1" is an odd number. Therefore, the voltage level of the data line is set to a voltage level symmetrical on both the positive and negative sides with respect to the "predetermined reference voltage level". Is done. This "predetermined reference voltage level" can be made to match the voltage level of the scanning line at the time of non-selection.

That is, when the number of simultaneously selected scanning lines is an even number, the center voltage level among the voltage levels of the data lines can be made to match the voltage level when the scanning line is not selected. . Therefore, in order to realize the display-off state, it is not necessary to newly add the same voltage level as the voltage level when the scanning line is not selected as the voltage level of the data line. Therefore, the design is simplified, the circuit is not complicated,
This is advantageous for low power consumption.

FIG. 16A (FIG. 1B) shows the voltage levels of the scanning lines and the data lines when the driving method of simultaneously selecting four scanning lines is adopted. In FIG. 16A, the left side is the voltage level of the scanning line, and the right side is the voltage level of the data line. Since L = 4, the five voltage levels of the data lines, V _Y1 , V _Y2 , Vc, V _Y4 , V _Y5 (L +
The voltage level of 1) is prepared. And V _Y1 , V
_Y2 , _VY4 , and _VY5 are levels set symmetrically with respect to Vc. Vc is nothing but the non-selection voltage level of the scanning line. Therefore, when setting the display-off mode area, the voltages of the scanning lines and the data lines are set to V
What is necessary is just to fix to c.

When the simultaneous selection number “L” of the scanning lines is odd, the number of voltage levels of the data lines is even, and there is no reference voltage at the center of each voltage level. Therefore, in this case, it is necessary to newly add a level corresponding to the above-described Vc to the voltage level of the data line as a voltage level for implementing the display-off mode.

As described above, the number L of the simultaneously selected scanning lines in the multi-line driving is desirably one of 2, 4, 6, and 8.

This is because, when the number of simultaneously selected scanning lines is increased, the scale of a circuit for realizing the driving is increased, which contradicts the demand for lower power consumption. Therefore, the number L of the simultaneously selected scanning lines
Is realistic for 2,4,6,8.

(9) Eighth Embodiment A. Device Configuration FIGS. 17 and 18 show configuration examples of a liquid crystal display device that employs a multi-line driving method and can appropriately set an area in a display-off mode.

First, the configuration of the liquid crystal display device shown in FIG. 17 will be described.

DM in module controller 2340
The A control circuit 2344 includes a microprocessor (MPU)
Upon receiving an instruction from the 2300, the video RAM (VRA)
M) 2320, read out one frame of image data via the system bus 2420, and send the image data (DATA) to the data line driving circuit together with the clock (XCLK).

The data line driving circuit (indicated by a dashed line in FIG. 17) includes a control circuit 2000, an input buffer 2011, a frame memory 252, an output shift register 2021, a decoder 258, and a voltage selector 2100.
Is provided.

Reference numeral 2400 denotes an input touch sensor, and reference numeral 2410 denotes a touch sensor control circuit. The input touch sensor 2400 and the touch sensor control circuit 2410 may be deleted when unnecessary.

Control signal generating circuit 2342 in module controller 2340 receives a command from MPU 2300 and outputs a first display control signal (OFF) to control circuit 2000 in the data line driving circuit. The control circuit 2000 changes the level of the second display control signal (DOFF) supplied to the voltage selector 2100 according to the level of the first display control signal (OFF). As a result, the drive output of the corresponding data line is fixed at the above-described voltage level Vc, and the screen is in the display-off mode.

A power supply circuit (voltage source circuit) 2420
Supplies a predetermined voltage to the data line driving circuit (X driver) and the scanning line driver (Y driver) 2200.

Next, the configuration of the liquid crystal display device shown in FIG. 18 will be described.

In the liquid crystal display device shown in FIG. 17, a multi-line drive (MLS
In the liquid crystal display device of FIG. 18, a data line drive circuit (indicated by a dashed line in the figure) is directly connected to a system bus 2420 of the microcomputer, and the MPU 2300 directly controls the MLS. It is configured to control driving. The data line driving circuit includes an interface circuit 2440, a control circuit 2450, and an oscillation circuit 24.
30 and the like. The display control signal (DOFF) is supplied to the control circuit 2450 via the interface circuit 2440. The display control signal (D
The area of the display-off mode can be appropriately set according to the level of (OFF) as in the case of FIG.

Next, an example of the configuration of the voltage selector 2100 shown in FIGS. 17 and 18 will be described with reference to FIG.

The voltage selector of FIG. 19 has a configuration similar to the configuration shown in FIG. That is, the shift register 25 that temporarily stores the display control data (DOFF)
6, the output of the MLS decoder 258 and the shift register 2
Logic gate 40 receiving 56 stored data as input
4, 406, 408, 410, 412 and the like. The switches SW1 to SW1 are output by the outputs of the logic gates.
The opening and closing of SW5 is controlled, and a desired voltage is applied to the liquid crystal panel 22.
It is applied to 50 data lines. Similarly to the display device of FIG. 9, the start position of the area to be set to the display off mode can be freely set in units of each output of the data line driver by the value of the display control data (DOFF).

B. Advantages and features of the MLS driving method Advantages and features of the MLS driving method will be described below. By applying the method of creating the display-off mode screen described in the first embodiment to the MLS driving method having the following features, it is possible to further reduce the power consumption of the liquid crystal display device. Further, the display quality can be improved.

In the MLS driving method, STN (Super T)
This is a technique for simultaneously selecting a plurality of scanning lines in a simple matrix type liquid crystal panel such as a liquid crystal panel. Thereby, the driving voltage of the scanning line can be reduced.

Further, as shown in the upper part of FIG. 20, in the conventional line-sequential driving method, the interval between the selection pulses is wide and the transmittance of the liquid crystal panel decreases with time. The luminance (transmittance) in the transmission state is reduced. On the other hand, as shown in the lower part of FIG. 20, according to the MLS driving method, the interval between the selection pulses can be narrowed, so that the transmittance (luminance) of the liquid crystal panel does not decrease much and the average transmittance increases. Therefore, the contrast is also improved.

C. Principle of MLS Drive Method As shown in FIG. 21, consider a case where two scanning lines X1 and X2 are simultaneously driven to turn on / off a pixel at a position where the scanning line and the data line Y1 intersect.

The ON pixel is set to “−1” and the OFF pixel is set to “+”
1 ". The data indicating this ON / OFF is stored in the frame memory. The selection pulse is represented by two values of "+1" and "-1". The data line Y
The drive voltage of 1 has three values of “−V2”, “+ V2”, and “V1”.

"-V2" and "+ V" are applied to the data line Y1.
2 or V1 is determined by the product of the display data vector d and the selection matrix β.

In the case of FIG. 21A, d · β = −2, and in the case of FIG. 21B, d · β = + 2.
In the case of FIG. 21C, d · β = + 2, and FIG.
In the case of (d), d · β = 0.

When the product of the display data vector d and the selection matrix β is "-2", "-V2" is selected as the data line driving voltage, and when "+2", "+ V2" is selected. , “0”, “V1” is selected.

When the calculation of the product of the display data vector d and the selection matrix β is performed by an electronic circuit, a circuit for determining the number of mismatches between the corresponding data of the display data vector d and the selection matrix β may be provided. .

That is, when the number of mismatches is "2", "-V2" is selected as the data line drive voltage. When the number of mismatches is “0”, the data line driving voltage is “+ V
Select "2". When the number of mismatches is “1”,
“V1” is selected as the data line drive voltage. In the MLS drive for simultaneously selecting two lines, the data line drive voltage is determined as described above, and the selection of the pixel is performed twice within one frame period, thereby displaying the on / off state of the pixel.
Since the selection period is provided a plurality of times, a decrease in transmittance in a non-selection period is reduced, and the average transmittance (luminance) of the liquid crystal panel is improved. Therefore, the contrast of the liquid crystal panel is also improved.

D. Specific Example of MLS Driving Hereinafter, an operation in a case where four scanning lines are simultaneously selected to drive a simple matrix type liquid crystal display device will be specifically described with reference to FIG.

For the scanning line, three (+ V1, 0, -V1) voltage levels are appropriately selected in accordance with a scanning voltage pattern defined by a preselected orthogonal function system.
This is applied to each of the scanning lines. Examples of the scanning voltage pattern are shown in FIGS. 23A and 23B.

For example, as shown in FIG. 22A, four scanning lines X1 to X4 are simultaneously selected.

At this time, the scanning voltage pattern is compared with the display data pattern, and the voltage level determined by the number of mismatches (any one of five voltage levels of -V3, -V2, 0, + V2, + V3) Is applied to each data line by the data line drive circuit. Hereinafter, a procedure for determining the voltage level applied to the data line will be described.

The scanning voltage pattern is when the selection voltage is + V1 (+), when the selection voltage is -V1 (-), and when the display pattern is ON display data (+) and OFF display data ( −). In the non-selection period, the number of mismatches is not considered.

In FIG. 22, the period required to display one screen is defined as one frame period (F), and all the scanning lines are set to one frame.
The period required for selecting one scan line is defined as one field period (f), and the period required for selecting one scan line is defined as one selection period (H).

Here, “H _1st ” in FIG. 22 is the first selection period, and “H _2nd ” is the second selection period.

Also, f _1st is the first field period, and f _2nd is the second field period. Also, F
_1st is the first frame period, and F _2nd is the second frame period.

In the case of FIG. 22, the first field period f
The first selection period in _1st (H _1st) 4 chosen in
The scanning patterns of the lines (X1 to X4) are set in advance in FIG.
2 (a), the value is always (++-+) regardless of the state of the display screen.

Here, considering the case where full-screen display is performed, (pixel (X1, Y1), pixel (X2, Y1), pixel (X
The display pattern in the first column corresponding to (3, Y1) and the pixel (X4, Y1)) is (++++). When the two patterns are compared in order, the first, second, and fourth polarities match, and the third pattern differs. That is, the number of mismatches is “1”. If the number of mismatches is “1”, 5 levels (+
(V3, + V2, 0, -V2, -V3) -V2 is selected from a certain voltage level. Thus, in the case of the scanning lines X1, X2 and X4 for which + V1 is selected, the voltage applied to the liquid crystal element is increased by the selection of -V2, while the case of the scanning line X3 for which -V1 is selected. In this case, the voltage applied to the liquid crystal element is reduced by selecting -V2.

The voltage applied to the data line in this manner corresponds to the "vector weight" at the time of the orthogonal transformation, and a true display pattern is reproduced when all the weights are added to the four scanning patterns. Voltage levels are set so that

Similarly, when the number of mismatches is "0", -V
3, 0 level when the number of mismatches is "2", + V2 when the number of mismatches is "3", and + V3 when the number of mismatches is "4"
Select V2 and V3 have a voltage ratio (V2: V3 = 1: 1).
2).

In the same manner, for the four scanning lines X1 to X4, the number of inconsistencies in the columns of the data lines from Y2 to Ym is determined, and the obtained data of the selected voltage is transferred to the data line driving circuit. During the first selection period, the voltage determined by the above procedure is applied.

Similarly, when the above procedure is repeated for all the scanning lines (X1 to Xn), the operation in the first field period (f _1st ) is completed.

Similarly, in the second and subsequent field periods, when the above procedure is repeated for all the scanning lines, 1
One frame (F _1st ) is completed, and one screen is displayed.

When the voltage waveform applied to the data line (Y1) when the entire surface is turned on is obtained in accordance with the above procedure, the result is as shown in FIG. 22B, and the voltage waveform applied to the pixel (X1, Y1) is obtained. Is as shown in FIG.

The above is a description of a specific example of the MLS driving method.

(10) Ninth Embodiment In this embodiment, the boundary position between a screen not used for image display and a screen to be displayed is controlled on the Y side (scanning line side) of the display panel. Will be described.

That is, as shown in FIG. 24A, the display control signals DOFF3 and DOFF4 are transmitted to the scanning line driving circuits 50 and 6.
0, for example, as shown in FIG. 24B, the screen of the liquid crystal panel 70 is
It is divided into an area 84 not used for image display.

Such display control can be realized, for example, by performing driving as shown in FIG. That is,
In the driving method shown in FIG. 25, only the scanning lines in charge of the area 502 used for image display are selected, and the scanning lines in the other area 504 are excluded from the selection.

As a result, the size of the display panel is substantially changed, and the driving duty is reduced.
It changes from "N" to "N / 2". Therefore, the voltage supplied from the variable voltage source 510 to the scanning line driving circuit is changed by the control signal V _CON in accordance with the change in the duty.

In the example of FIG. 25, the drive duty is 1
Therefore, the voltage supplied from the variable voltage source 510 to the scanning line driving circuit can be reduced to about half.

On the other hand, area 504 not used for image display
Is an area that does not function as a display screen at all.

The variable voltage source 26 can be configured using, for example, a bootstrap circuit as shown in FIG.

The bootstrap circuit of FIG. 26 operates as follows.

When the gate voltage Vg of the transistor Q2 becomes "H" and the transistor Q2 is turned on, the current i
1 flows to charge the capacitor C _O. by this,
The voltage across the capacitor C _O is V1.

Next, when the transistor Q2 is turned off,
The current i2 flows to turn on the transistor Q1, and the potential at the point A1 becomes equal to Vs.

At this time, the potential at point B1 is boosted to Vs + V1. Therefore, various voltages can be generated by appropriately setting V1 and Vs.

FIG. 5 shows a configuration of a liquid crystal display device adopting the MLS driving method for realizing the driving method of the present embodiment.
It is shown in FIG. The MLS controller 2340 changes the output voltage of the variable voltage source 510 according to the control signal V _CON in response to the display control by the display control signals DOFF3 and DOFF4.

(11) Tenth Embodiment In this embodiment, the size of an image is enlarged without changing the driving duty. That is, a process of converting the resolution of the image is performed. Hereinafter, this processing will be described with reference to FIG.
This will be described with reference to FIGS.

As shown in FIG. 28A, the display panel
It has two display areas “A” and “B”, and the Y driver 520 is responsible for driving the scanning lines in the display area “A”, and the Y driver 530 is responsible for driving the scanning lines in the display area “B”. And

Using the method described with reference to FIG. 25, an image is displayed only in area "A" as shown in FIG. 28B. At this time, the area “B” is an area that does not contribute to any display. In this state, only the upper half of the display panel is used for image display, and the impact on the viewer of the image is weak.

Therefore, as shown in FIG. 28C, the same image is displayed on two pixels adjacent in the vertical direction, and thereby the image size is doubled in the vertical direction. In this case, although the image size is doubled, the driving duty is the same as in FIG. 28B because the same image is only displayed on two pixels. Therefore, power consumption does not change so much. However, the resolution of the image is halved and the quality of the displayed image is reduced. However, by doubling the size of the image, the impact on the viewer is increased, and the display function is enhanced accordingly.

The scanning line driving circuit in the liquid crystal display device using the MLS driving for realizing the above-described process of doubling the image size (resolution is １ ／) without changing the driving duty. Figure 2 shows an example of the main part configuration
It is shown in FIG. FIGS. 30A and 30B specifically show the conditions of each part when performing the display as shown in FIG. 28B and when performing the double-width display as shown in FIG. 28C, respectively.

The circuit 600 shown in FIG.
8A and input terminals 1B, 2B,... 8B. Then, any of the data D0, D1, D2, and D3 is input to each input terminal as illustrated. The data D0, D1, D2, and D3 are data for determining the voltage applied to the scanning line.

When the control signal B0 is "L",
8A is output to output terminals 1Y, 2Y... 8Y. On the other hand, when the control signal B0 is "H", the data input to each terminal of 1B, 2B... 8B is output to the output terminals 1Y, 2Y.
..Output to 8Y.

On the other hand, each output terminal 1Y, 2Y of the circuit 600
.. Is connected to one input terminal of a two-input AND gate 610-617. The enable control signal EN1 is input to the other input terminal of the two-input AND gates 610 to 613, and the two-input AND gate 614 is input.
The enable control signal EN is provided to the other input terminals
2 has been entered.

In order to perform the display as shown in FIG. 28B, as shown in FIG. 30A, the control signal B0 is set to "L", the enable control signal EN1 is set to "H", and the enable control signal EN2 is set to "L". I do. Thereby, the output terminals OUT1-OUT of the two-input AND gates 610-614 in FIG.
Data D0, D1, D2, and D3 are output to T4, and the voltages of the four scanning lines are determined based on each data.

On the other hand, when performing double-width display as shown in FIG. 28C, as shown in FIG. 30B, the control signal B0 is set to "H".
The enable control signal EN1 is set to “H”, and the enable control signal EN2 is also set to “H”. As a result, FIG.
9 two-input AND gates 610 to 617 and output terminals OU
Data T0, D0, D
1, D1, D2, D2, D3, and D3 are output, and voltages of eight scanning lines are determined based on each data. That is,
The same scanning line driving voltage is applied to adjacent scanning lines. This doubles the image size.

In the above example, the image size was doubled.
If a similar technique is used, the image size can be increased four times, eight times, or the like. In any case, display is performed by increasing the impact of icon display and the like on the user of the liquid crystal panel with the same low power consumption as when a part of one screen is partially turned off. Has the effect of impressing

(12) Eleventh Embodiment In the ninth embodiment, referring to FIG. 24 and FIG. 25, the boundary position between the screen not used for image display and the screen to be displayed is determined by the Y position on the display panel. The display control method when the control is performed on the scanning side (scanning line side) has been described. However, this method requires a variable voltage source because the driving duty changes.

In the present embodiment, similar display control is performed without changing the drive duty.

As shown in FIG. 31, in the present embodiment,
Without changing the driving duty “N”, the scanning line S1
To S6 are all selected.

In the screen of display panel 500, area 502 assigned to scanning lines S1 to S3 is an area used for image display, and area 504 assigned to scanning lines S4 to S6 is not used for image display. Area.

Now, six pixels M along the data line L1
Considering 1 to M6, the pixels M1 to M3 are turned on, and the pixel M4
Consider turning off M6. If the pixels M4 to M6 are simply turned off, when the scanning lines S4 to S6 are selected,
What is necessary is just to fix the voltage level of the data line L1 to the above-mentioned Vc (voltage when the scanning line is not selected).
The display of M3 becomes extremely dark, and an appropriate display cannot be performed. This is because the circuit is designed in the display device on the assumption that a voltage for performing a predetermined display (a voltage for performing on / off display) is always applied to the data line L1. That is, it is a nonstandard driving method to continuously apply the voltage level Vc when the scanning line is not selected to the data line L1.

Therefore, in this embodiment, the scanning lines S4 and S4
At the timing when S5 and S6 are to be selected, the non-selected voltage Vc is applied to the scanning line, and one of the voltages to be applied when performing normal on / off display is applied to the data line L1. Apply one. Thereby, the pixels M1, M
2, M3 while maintaining the display properly.
5 and M6 can be turned off. At this time, the area 504 in the display off state is set.
In the case of, since the voltage level of the scanning line is fixed at Vc and the polarity is not inverted, the power consumption is reduced even if a voltage for displaying on the data line is applied.

Further, in this embodiment, it is not necessary to use a variable voltage source because the driving duty does not change, so that the configuration of the voltage source circuit is simple, and the power consumption can be reduced.

FIG. 32 is a timing chart showing the operation when the driving method of the present embodiment is applied to the MLS driving method of simultaneously selecting four lines. FIG. 32 shows signal waveforms in the first and second field periods for convenience.

In FIG. 32, a period from time t1 to t2 and a period from time t3 to t4 are periods during which an image is properly displayed, and a period from time t2 to t3 is a period during which display is turned off. During the period from time t2 to time t3, the corresponding scanning lines Y101 to Y200 are maintained at the non-selection voltage level Vc, while “V _Y4 ” is applied to the data line instead of “Vc”. Understand.

FIG. 33 shows a configuration of a liquid crystal display device employing the MLS driving method and performing the operation shown in FIG. FIG.
7, a fixed voltage source 512 is provided. Further, MLS controller 2340, and sends a display control signal DOFF3, DOFF4, the scanning line drive output causes fixed to Vc, In accordance with this, sends out a control signal V _XC, the output of the X driver 520, 530 _Is fixed to a predetermined voltage (for example, V _Y4 shown in FIG. 32).

(13) Twelfth Embodiment FIGS. 34A and 34B show a configuration of a main part of a liquid crystal display device of the present embodiment. A feature of this embodiment mode is that at least one of the scanning lines and the data lines is set to a floating state (high impedance state) in terms of potential when the screen is in the display off state. Thereby, useless power consumption in the liquid crystal panel can be reduced.

As shown in FIG. 34B, the liquid crystal panel encloses the liquid crystal 810 between the conductor layers 800 and 820, generates a predetermined voltage from the voltage source 700, drives the liquid crystal, and performs a predetermined display. Note that the conductor layers 800 and 820 are constituent materials of the scanning lines and the data lines.

Even when the same voltage is applied to the conductor layers 800 and 820 to turn off the display, a slight difference occurs in the potential of each conductor layer due to various factors. When a path connecting the liquid crystal 810 and the voltage source 700 is formed, the conductor layer 80
0 and the conductor layer 800 due to the potential difference between
Alternatively, charge is injected from the conductor layer 820 to the liquid crystal 810, and current flows. This current is useless current.

Therefore, as shown in FIG.
Switches 711 and 72 in the voltage application path to 00 and 820
6 to open at least one of the switches 711 and 726 in the high impedance mode. Thus, the current path is cut off, and no useless current flows. Thereby, power consumption can be reduced.

However, since the scanning line or the data line is in a floating state in terms of potential and is unstable, an undesirable pattern or the like may appear on the screen due to static electricity or the like. Therefore, when at least one of the scanning line and the data line is set to a floating state in terms of potential, it is desirable to cover the screen with a cover so as not to give a discomfort to the user of the liquid crystal panel.

In the liquid crystal panel of FIG. 34A, switches 711 to 716 in switch means 710 and switches 721 to 726 in switch means 720 are all open. Therefore, the scanning lines L1 to L6 and the data lines S1 to S6 are all in a floating state in terms of potential. Then, the cover 750 covers the screen.

FIGS. 35 and 36 show a configuration for realizing a mode (high impedance mode) in which the potential of a data line is set to a floating state and display is prohibited in a liquid crystal display device employing the MLS driving method.

That is, as shown in FIG. 35, a control signal Hi-Z instructing the high impedance mode is input to the multi-line decoder 860. The multi-line decoder 860 is also supplied with the display control signal DOFF for instructing the above-mentioned display off state.

FIG. 36 shows an example of a specific configuration of multi-line decoder 860 and voltage selector 870.

The multi-line decoder 860 includes logic gates NA1 to NA5 for decoding image data (DATA) and a display control signal DOFF, and a control signal Hi-.
Z and AND gates NB1 to NB5 for decoding the outputs of the logic gates NA1 to NA5.

When the control signal Hi-Z becomes "L", the outputs of the AND gates NB1 to NB5 are forcibly fixed to "L". As a result, the switches SW1 to SW5 in the voltage selector 870 are all opened, and the data lines are in a floating state in terms of potential. As a result, the display screen enters the high impedance mode.

(14) Thirteenth Embodiment FIG. 37 shows a characteristic structure of a liquid crystal display device of the present embodiment.

[0199] The liquid crystal display device of this embodiment includes a first display panel 910 and a second display panel 920.

By appropriately setting the number of scanning lines (driving duty) of the first display panel 910, the voltage V _X1 supplied from the voltage source 930 to the scanning line driver (Y1) 960 and the data line driver (X1) The voltage V _Y5 supplied to the 940 is made equal. Therefore, the voltage source 930 only needs to generate a common voltage, and the configuration of the power supply circuit 930 is simplified, thereby reducing power consumption.

Both panels 910 and 920 are ML
An image is displayed by the S driving method. In FIG. 37, X driver (X1) 940, X driver (X2) 942, and Y driver (Y1) 960 are connected to first display panel 9
10 is provided for driving the motor. An X driver (X3) 944, an X driver (X4) 946, a Y driver (Y2) 962, and a Y driver (Y3) 964 are provided for driving the second display panel.

[0202] The first display panel 910 is, for example, a dedicated panel for displaying simple icons, and the second panel 920 is a general-purpose panel for performing other various displays. Then, the number of scanning lines of the first panel 910 is considerably smaller than the number of scanning lines of the second panel 920.

This is because the first display panel 910 only needs to display icons, and therefore, there is no problem even if the display area is elongated and small, and the driving duty of the first display panel 910 is reduced. Then, the level of the voltage supplied to the X driver 940 and the Y driver 9
This is because the level of the voltage supplied to 60 is designed to match.

That is, as shown on the right side of FIG.
When the S driving method is adopted, the selection voltage level of the scanning line
Bell V_X1(-V_X1) And the data line selection voltage level V_Y5
(V _Y1) Usually does not match. However,
For example, the number of simultaneously selected scanning lines h = 4, the threshold voltage V of the liquid crystal
When th = 2.0 V, the first display panel 910
Assuming that the number of inspection lines is 16, V_X1, V_Y5Each level
Is 3.27V, which is in agreement.

As described above, by appropriately adjusting the number of scanning lines (adjusting the driving duty), the selection voltage level of the scanning lines and the selection voltage level of the data lines can be matched. The display device of FIG. 37 utilizes this fact to simplify the configuration of the voltage source 930 to reduce power consumption. Thus, the icons can be displayed with low power consumption.

Further, using the second display panel 920,
Various versatile displays are also possible.

(15) Fourteenth Embodiment In this embodiment, a drive circuit for driving a display matrix has both a function for driving a scanning line and a function for driving a data line. Let me know.

The function is appropriately switched according to the shape and size of the image display area to change the drive duty, thereby reducing the voltage when selecting the scanning line and reducing the power consumption during image display. Reduce.

A specific description will be given with reference to FIG. FIG.
, An area 912 is an area used for image display (display area), and an area 922 is an area not used for image display (display-off mode area).

At present, the driver 941 functions as a data line driver (X driver), and the driver 961
And driver 963 are scanning line driver (Y driver)
Functioning as

Here, attention is paid to the shape of the display area 912. The display area 912 has a vertically elongated shape. That is, the height is long and the width is short. Therefore, in such a case, the driver 941 functions as a scanning line driver (Y driver), and the driver 961 and the driver 963 function as data line drivers (X driver). Then, the number of scanning lines (driving duty) is reduced, and the selected voltage level of the scanning lines can be reduced by the reduced duty. Thus, power consumption of the display device can be reduced.

(16) Fifteenth Embodiment Hereinafter, an electronic apparatus equipped with a display device of the present invention will be described.
This will be described with reference to FIGS.

[0213] Fig. 39A shows the appearance of a mobile phone in normal use, and Fig. 39B shows the appearance of a mobile phone used as a portable terminal.

The mobile phone has a screen 1000 and a screen 10
10, an antenna 1100, a touch key 1200,
A microphone 1300 and a panel 1400 are provided. Screen 1
000 and the screen 1010 constitute one liquid crystal display panel.

As is clear from FIGS. 39A and 39B,
During normal use, screen 1010 is hidden below panel 1400. Therefore, during normal use, the screen 1010 is in the display off mode or the high impedance mode.

When used as a portable terminal, panel 400 is folded down as shown in FIG. 39B, and screen 1010 appears. In this state, the display-off mode or the high-impedance mode of the screen 1010 has been released, so that various images can be displayed using the screen 100 and the screen 1010.

FIGS. 40A and 40B are diagrams showing the usage of the portable electronic dictionary.

The portable electronic dictionary 1500 is usually
0A, in which case the screen 151
A desired display is made using 0.

When the screen 1510 is not enough, the screen 1520 is pushed upward as shown in FIG. 40B, and the image display area is enlarged. FIG.
In the state of 0A, the screen 1520 is hidden inside the main body and cannot be seen, so that the display 1520 is in the display off mode or the high impedance mode.

FIGS. 41A and 41B are diagrams each showing an appearance of a portable electronic device.

A portable electronic device shown in FIG.
, A display panel 1620, and a cover 1610.
The cover 1610 can slide left and right, so that the size of the display area can be changed appropriately,
The display screen can be divided. An area of the display panel that is hidden under the cover 1610 and cannot be seen is in the display off mode or the high impedance mode.

In FIG. 41B, two covers 161 are provided.
2,1614. Each cover can be slid left and right, and the size of the display area can be changed appropriately. Areas of the display panel 1622 that are hidden behind the covers 1612 and 1614 and cannot be seen are in the display off mode or the high impedance mode.

FIGS. 42A and 42B are diagrams showing a usage form of the portable electronic translator.

Screen 1710 of Portable Electronic Translator 1700
FIG. 42A shows English words to be translated, as shown in FIG. 42A. Then, as shown in FIG. 42B, when the cover 1720 is slid, a Japanese translation of the English word is displayed on the screen 1730.

The cover 1612,1 of the display panel
The screen hidden under the area 614 and invisible is in the display off mode or the high impedance mode.

In the portable telephone shown in FIG.
The display screen of the display panel is divided into area "A" and area "B".
A simple image such as an icon is displayed in the area "A", and the area "B" is set to the display off mode or the high impedance mode.

In the above-described electronic apparatus, a desired image can be displayed with extremely low power consumption by partially setting the area not contributing to display to the display-off mode or the high-impedance mode.

[Brief description of the drawings]

FIG. 1A is a diagram showing an example of voltage levels of a scanning line and a data line in a method for driving a display device of the present invention, and FIG. 1B is another example of a voltage level of a scanning line and a data line. FIG.

FIG. 2 is a diagram for explaining the principle of a method for driving a display device of the present invention.

FIG. 3A is a diagram showing an example of a configuration of a simple matrix type liquid crystal display device employing a driving method of the present invention;
FIG. 3B is a diagram showing an example of a display screen of the device in FIG. 3A.

FIG. 4A is a diagram showing another example of the configuration of a simple matrix type liquid crystal display device employing the driving method of the present invention, and FIG. 4B is a diagram showing an example of a display screen of the device of FIG. 4A. It is.

FIG. 5 is a driving method for selecting scanning lines one by one (AT
FIG. 9 is a diagram showing voltage levels of scanning lines and data lines in the present invention when (P driving method) is adopted.

FIG. 6 is a diagram illustrating a relationship between an applied voltage and a light transmittance of a liquid crystal display device.

FIG. 7A is a diagram showing a configuration example of a simple matrix type liquid crystal display device employing the driving method of the present invention.
7B is a timing chart for explaining a characteristic operation in the device of FIG. 7A.

8A is a timing chart illustrating an example of an operation of the liquid crystal display device of FIG. 7A, and FIG. 8B is a timing chart illustrating another operation example.

FIG. 9 is a diagram showing a configuration example of a simple matrix type liquid crystal display device employing the driving method of the present invention.

10A is a timing chart illustrating an example of the operation of the liquid crystal display device in FIG. 9, and FIG. 10B is a timing chart illustrating another operation example.

FIG. 11 is a diagram illustrating a configuration example of a liquid crystal display device of the present invention.

FIG. 12A, FIG. 12B, and FIG.
FIG. 12 is a diagram illustrating a mode of display control in the liquid crystal display device of FIG. 11.

FIG. 13 is a diagram showing an example of a configuration of a main part of the liquid crystal display device of the present invention.

FIG. 14 is a diagram showing another example of the configuration of the main part of the liquid crystal display device of the present invention.

15 shows a specific circuit configuration of the decoder in FIG.

FIG. 16A is a diagram showing voltage levels of scanning lines and data lines when four scanning lines are simultaneously selected and driven, and FIG. 16B is a diagram showing the number of simultaneous selections and the number of voltage levels of data lines; FIG.

FIG. 17 is a diagram illustrating an example of a configuration of a liquid crystal display device of the present invention employing a multi-line driving method.

FIG. 18 is a diagram showing another example of the configuration of the liquid crystal display device of the present invention employing the multi-line driving method.

FIG. 19 is a diagram showing an example of a configuration of a main part in the liquid crystal display device of FIG. 17 or FIG.

FIG. 20 is a diagram for explaining features of the multi-line driving method.

FIG. 21 is a diagram illustrating characteristics of the operation of the multi-line driving method.

FIG. 22 is a diagram illustrating an example of changes in voltages of a scanning line, a data line, and a pixel portion in a liquid crystal display device employing a multi-line driving method.

FIGS. 23A and 23B are diagrams illustrating examples of scanning voltage patterns in the multi-line driving method.

24A is a diagram illustrating an example of a configuration of a liquid crystal display device of the present invention (a configuration in a case where screen control is performed along the arrangement direction of scanning lines), and FIG. 24B is a diagram illustrating the liquid crystal display device of FIG. FIG. 4 is a diagram illustrating a mode of display control in the device.

FIG. 25 is a diagram showing a specific example of display control in the liquid crystal display device of the present invention.

26 is a diagram illustrating an example (bootstrap circuit) of a specific configuration of the variable voltage source illustrated in FIG. 25;

FIG. 27 is a diagram illustrating a configuration example of a liquid crystal display device that employs a multi-line driving method to realize the display control illustrated in FIG. 25;

28A shows a screen where no image is displayed, FIG. 28B shows a state where an image is displayed on a half screen, and FIG. 28C shows a state where the display image of FIG. (表示 display state).

FIG. 29 is a diagram showing a configuration of a circuit for performing the resolution conversion shown in FIGS. 28B and 28C.

30A and 30B are diagrams for explaining the operation of the circuit shown in FIG. 29;

FIG. 31 is a diagram showing a specific example of display control in the liquid crystal display device (device employing the multi-line driving method) of the present invention.

FIG. 32 is a timing chart for explaining the operation of the device in FIG. 31.

FIG. 33 is a diagram illustrating a configuration example of a liquid crystal display device that realizes the display control of FIG. 31;

FIG. 34A is a diagram illustrating an example of a main configuration of a liquid crystal display device according to the present invention, and FIG. 34B is a diagram illustrating features of the configuration in FIG. 34A.

FIG. 35 shows the display control shown in FIGS. 34A and 34B.
FIG. 9 is a diagram illustrating a main configuration when applied to a liquid crystal display device employing a multi-line driving method.

FIG. 36 is a diagram showing a more specific circuit configuration of the configuration of FIG. 35;

FIG. 37 is a diagram illustrating a configuration example of a liquid crystal display device of the present invention.

FIG. 38 is a diagram illustrating a configuration example of a liquid crystal display device of the present invention.

FIG. 39A is a front view of a mobile phone equipped with the display device of the present invention during normal use, and FIG. 39B is a front view of FIG.
It is a front view at the time of special use of the mobile phone of 9A.

40A and 40B are perspective views of a portable electronic dictionary equipped with the display device of the present invention.

41A and 41B are diagrams each illustrating an outer shape of an electronic device on which the display device of the present invention is mounted.

42A and 42B are perspective views of a portable electronic translator equipped with the display device of the present invention.

FIG. 43 is a diagram illustrating an outer shape of a mobile phone equipped with a display device.

FIG. 44 is a diagram showing a main configuration of a normal simple matrix type liquid crystal display device.

FIG. 45 is a diagram showing voltage levels of scanning lines and data lines in a conventional method of driving a liquid crystal display device.

FIG. 46 is a timing chart for explaining the operation of a normal simple matrix liquid crystal display device.

FIG. 47 is a diagram showing a problem of a conventional driving method of a liquid crystal display device.

[Explanation of symbols]

2,100,110,280,5000 X driver (signal line driving circuit) 4,20,520,530,4000 Y driver (scanning line driving circuit) 6,70 Liquid crystal panel 10-40 Data line driving IC 50,60 Scanning Line drive IC 80 Image display area 90 Display off area 130 OR gate 200 Operation timing controller 210 Data shift register 220 Latch 230 Level shifter 240 Voltage selector 250 Liquid crystal panel 252 Frame memory 256 Shift register 258 MLS decoder 270 Display screen 280 X driver 290 Y driver 300 to 330 Decoder 340 to 370 Voltage selector 400 Decoder 404 to 412 Logic gate 500 Liquid crystal panel 502, 504 Screen 510 Variable power supply 512 Fixed power supply 520,530 X driver 540,550 Y driver 600 circuit 610-617 input AND gate 700 voltage source 710,720 switch means 711-717,721-726 switch 750 cover 800,820 conductor layer 810 liquid crystal 860 multi-line decoder 870 voltage selector 900 Liquid crystal panel 910 First display panel 912, 922 Display area 920 Second display panel 930 Voltage source 940-946 Data line driver 960-964 Scanning line driver 1000, 1010 Screen 1100 Antenna 1200 Touch sensor 1300 Microphone 1400 Panel 1500 Mobile Electronic dictionary 1510, 1520 screen 1600 frame 1610, 1612, 1614 cover 1620 display panel 1700 portable electronic translator 17 10, 1730 screen 1720 cover 2000 control circuit 2011 input buffer 2021 output shift register 2100 voltage selector 2200 Y driver 2250 liquid crystal panel 2300 microprocessor (MPU) 2310 system memory 2320 video RAM 2330 auxiliary storage device 2340 MLS controller 2342 control signal generation circuit 2344 DMA control circuit 2400 Input touch sensor 2410 Touch sensor control circuit 2420 System bus 2430 Oscillator circuit 2440 Interface circuit 2450 Control circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shingo Isozaki 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (72) Inventor Makoto Katase 3-5-2-5 Yamato, Suwa-shi, Nagano Seiko-Epson Incorporated (72) Inventor Masuhide Ikeda 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation

Claims (7)

[Claims] 1. N scanning lines (N is an integer of 2 or more),
M (M is an integer of 2 or more) data lines, a plurality of display elements whose display state is controlled by a voltage applied to the scanning lines and a voltage applied to the data lines, and driving of the scanning lines A driving circuit for the display device, comprising: a driving circuit for driving the data line; and a driving circuit for driving the data line, the driving circuit for driving the scanning line having only one voltage level when the scanning line is not selected. Is input, and the display control signal causes the area assigned to the continuous K lines (K is an integer of 2 or more smaller than N) of the N scanning lines to be set as the non-display state area, and the other scanning lines An area assigned to the line is an area where an image can be displayed. The K scanning lines are held at the non-selected voltage level without applying a selection voltage, and the K scanning lines are not applied. Is originally selected During came period, said data line driving method of a display device and applying a voltage to be applied when performing display. 2. A scanning line according to claim 1, which is in charge of an area where an image can be displayed.
A method for driving a display device, wherein h (where h is an integer of 2 or more) scanning lines are simultaneously selected, and a scanning voltage based on a predetermined selection voltage pattern is applied to each of the scanning lines. 3. A display device employing the driving method according to claim 1. 4. The display according to claim 3, wherein the display device has a portion covering at least a part of a screen, and an area covered by the portion is the non-display state area. apparatus. 5. The display device according to claim 4, wherein the portion covering at least a part of the screen is one or a plurality of movable members. 6. The device according to claim 4, wherein a part of the screen is housed inside the main body, so that the part housed inside the main body becomes a non-display area, and the part housed inside the main body. The display device is characterized in that a portion of the display device becomes an area that can be displayed when the device goes out of the main body. 7. An electronic device equipped with the display device according to claim 3.