JP2005242384A - Display device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the power consumption of a display device such as a simple matrix type liquid crystal display device etc. <P>SOLUTION: Disclosed is a method for driving the display device equipped with N (N: an integer of ≥2) pieces of scanning lines Y1 to Y120, M (M: an integer of ≥2) pieces of data lines, a plurality of display elements (liquid crystal) whose display state is controlled with voltage applied to scanning lines and voltage applied to data lines, driving circuits 50 and 60 for the scanning lines, and driving circuits 10 to 40 for the data lines. A display control signal is inputted to the driving circuits for the scanning lines and with the display control signal, only (N-K=N/2) pieces of scanning lines are regarded as objects to be selected for display while K (e.g. K=N/2) pieces of successive scanning lines among the N pieces of scanning lines are excluded from objects to be selected, and then driven. In this case, a variable power source 510 makes the voltage level lower during the selection of the scanning line than driving of the N pieces of scanning lines. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  Simple matrix liquid crystal display devices are widely used in monitors for portable computers and portable electronic devices because they do not require expensive switching elements on the substrate and are inexpensive compared to active matrix liquid crystal display devices. ing.

  As a driving method of this simple matrix type liquid crystal display device, the following is known.

(1) APT method (IEEE TRANSACTIONS OF ELECTRON DEVICE, VOL, ED-21, No2, FEBRUARY 1974 P146-155 "SCANNING LIMITATIONS OF LIQUID-CRYSTAL DISPLAYS" P.ALT, P.PLESHKO, ALT & PLESHKO TECHNIC).
(2) Smart Addressing (LCD International '95, liquid crystal display seminar sponsored by Nikkei Business Publications, C-4 lecture number (1), Sanyo Tottori Electric, Mr. Matsushita).
(3) Multi-line driving method (for example, JP-A-5-46127 and JP-A-6-130910).
Japanese Patent Laid-Open No. 5-46127 JP-A-6-130910 JP-A-6-301010 JP 57-22289 A JP 57-38494 A JP-A-62-212431 JP-A-6-95621 JP 59-121391 A Japanese Patent Laid-Open No. 4-171481 JP-A-5-199482

  In recent years, in the field of portable electronic devices such as mobile phones and pagers, in addition to downsizing and weight reduction, there is an increasing demand for extending the time during which display can be performed without replacing the battery. Therefore, display devices mounted on portable electronic devices are strictly required to have low power consumption.

  The inventor has made 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 line and the signal line even in the display off state, and a voltage source for generating the AC waveform. It has been found that the power consumption in the circuit is large and the current flowing between the scanning line and the data line via the liquid crystal is large.

  The present invention has been made to solve such problems.

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

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

  According to this driving method, even if a driving method for displaying an image by periodically inverting the polarity of the selection voltage applied to the scanning line is employed, regardless of the polarity of the selection voltage of the scanning line, it is not selected. The voltage level is 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 line is set to the non-selection voltage and the data line is set to the same voltage, the voltage difference between the two disappears and the display is turned off (display off mode).

  Since there is only one non-selection voltage level, the configuration of the voltage source circuit that generates the non-selection voltage is simplified, and the power consumption in the voltage source circuit is reduced. Further, compared with the case where the non-selection voltage is periodically changed, it becomes easier to make the data line voltage coincide with the scanning line voltage, and the power consumption in the display panel due to the potential difference between the scanning line and the data line is also reduced. The Therefore, power consumption of the display device is reduced.

  Further, even when 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 by selecting a scanning line in the selection period, the threshold value of the liquid crystal is not exceeded and display is not performed.

  By utilizing this, by appropriately controlling the voltage applied to the data line, a part of the area can be set to the display off mode on one screen and a predetermined display such as an icon can be displayed on the other area. It becomes possible.

  In a preferred aspect of the present invention, a display control signal is input to each of the plurality of ICs for driving the data lines, and at least a part of the data line driving output of each IC is scanned by the display control signals. The voltage level when no is selected.

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

  According to a preferred aspect of the present invention, at least one of the display data or the clock for transferring display data is set in response to setting at least a part of the output for driving the data line to the voltage level when the scanning line is not selected. The supply to the two ICs is also stopped.

  Further reduction in power consumption can be promoted by stopping transmission of display data in an area that is in a display off state (area in display off mode) and a high-frequency clock used for transfer of the display data.

  In a preferred embodiment of the present invention, a display control signal is input to the data line driving circuit, and each of the data line driving outputs is individually controlled by the display control signal, so that a desired driving output is selectively scanned. The voltage level when no is selected.

  Thereby, it is possible to freely set an area in which the display is turned off.

  According to a preferred aspect of the present invention, the data line driving circuit is configured by a plurality of blocks, a display control signal is input to the data line driving circuit, and the data line driving output is output in block units by the display control signal. And the data line drive output of the corresponding block is set to the voltage level when the scanning line is not selected.

  Thereby, the area to be turned off can be freely set 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 scanning based on a predetermined selection voltage pattern is performed on each of the scanning lines. A voltage is applied, and a voltage determined based on a comparison between the selected voltage pattern and display data indicating the display state of the display element is applied to each of the data lines to perform a desired display, thereby displaying an image. When the state is not performed (screen in the image off mode), at least a part of the data line drive output is set to the voltage level when the scanning line is not selected by the display control signal input to the data line drive circuit. .

  The driving method for realizing the display off state (screen in the display off mode) is applied to a display device that employs so-called multiline driving.

  In this case, at the time of image display, the power consumption can be reduced by the effect of the multi-line driving method that the level of the selection voltage applied to the scanning line can be lowered, which is combined with the effect of reducing the power consumption when the display is off. Thus, power consumption can be further reduced.

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

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

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

  Increasing the number of scanning lines to be selected at the same time increases the scale of the circuit for realizing the driving, which is contrary to the demand for lower power consumption. Therefore, it is realistic that the number h of simultaneously selected scanning lines is 2, 4, 6, and 8.

  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 (an area that is in a display off mode). Set freely.

  Further, in a preferred aspect of the display device of the present invention, by designating each data line as a unit by decoding display control data and display data, or by specifying a combination of a plurality of display control signals, For example, an area in which the display is turned off is designated in a predetermined block unit.

  Further, in a preferable 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 state area (display off mode area), for example, unnecessary power consumption during standby is reduced. Try to suppress.

  Moreover, in the preferable aspect of the display apparatus of this invention, a display apparatus has a part which covers at least one part of a screen, and the area covered with the part turns into an area where a display is turned off.

  The display off area is hidden from the user. The portion covering at least a part of the screen can be composed of one or more movable members, for example, a sliding cover. Further, all or a part of the screen can be accommodated in the main body according to the use state.

  An electronic apparatus according to the present invention is an electronic apparatus equipped with a display device capable of appropriately designating the above-described display off state area.

Further, according to a preferred aspect 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, and the data lines A display device driving method comprising: a plurality of display elements whose display states are controlled by a voltage applied to a scanning line; a scanning line driving circuit; and a data line driving circuit.
A display control signal is input to the scanning line driving circuit, and K scanning lines (K is an integer of 2 or more smaller than N) among the N scanning lines are selected by the display control signal. In the case where display is performed by selecting only (NK) scanning lines, and driving of the (NK) scanning lines is executed, N scanning is performed. The voltage level at the time of selecting a scanning line is lowered as compared with the case of driving the line.

  When the boundary position of the area to be turned off is appropriately determined in the scanning line arrangement direction (Y direction), the K scanning lines in charge of the area not to be displayed are excluded from selection. is there. As a result, the duty (the number of drive scanning lines) in driving the display device changes, and accordingly, the selection voltage level of the scanning lines that can perform appropriate display also decreases. Power consumption can be reduced by lowering the selection voltage level.

  Further, the voltage level at the time of selecting the scanning line can be changed 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 aspect of the present invention, resolution conversion of a display image is performed when an image is displayed using a multiline driving method.

  In the resolution conversion, when the resolution 1 / Q (Q is an integer of 2 or more) is designated by the resolution conversion signal, the same scanning voltage is applied to consecutive Q scanning lines, thereby simultaneously (Q × h). ) This is done by selecting a scanning line. Resolution 1 / Q means that the image size is multiplied by Q without changing the duty in driving the display device. In this case, although the power consumption is substantially the same, the image is enlarged, so that the power of appealing to the user's vision increases.

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, and data lines In driving a display device including a plurality of display elements whose display states are controlled by an applied voltage, a scanning line driving circuit, and a data line driving circuit,
The voltage level of the scanning line at the time of non-selection is only one;
A display control signal is input to the scanning line drive circuit, and the display control signal displays an area in which K consecutive K out of N scanning lines (K is an integer of 2 or more smaller than N) is assigned. The other scanning lines are in charge of the display area, the K scanning lines are kept at the non-selected voltage level without applying the selection voltage, and K During the period in which the scanning line is to be originally selected, a voltage to be applied when displaying is applied to the data line.

  When the boundary position of the area to be in the display off state is appropriately determined in the arrangement direction (Y direction) of the scanning lines, the driving duty is selected as the selection target for the K scanning lines in charge of the area in the display off state. On the other hand, during the period corresponding to the area in which the display is turned off, the data line is supplied with a voltage level for display instead of the voltage when the scanning line is not selected. It is. Since the driving duty is not changed, there is no need to change the selection voltage level of the scanning line. Therefore, the configuration of the voltage source circuit is not complicated. The present driving method can also be applied when a driving method for simultaneously selecting a plurality of scanning lines is employed.

  Further, in a preferable aspect of the display device of the present invention, the above-described various driving methods are adopted, for example, in the standby state, areas other than the minimum display area are displayed in the display off state (display off mode). Screen) and reduce power consumption.

  In a preferred embodiment of the display device of the present invention, a plurality of switch means are provided in the voltage application path to the scan line or data line, and when the image is not displayed, the switch means is opened to scan line or data. The line is floated in terms of potential.

  In this case, the path connecting the data line with the scanning line and the electro-optical element such as liquid crystal existing between the scanning line and the data line is completely separated from the voltage source. Therefore, there is no possibility of unnecessary current flowing through the electro-optic element. However, since the scanning line and the data line may be unstable in potential and an undesired screen may be formed due to static electricity or the like, it is difficult for the user to cover the entire surface of the display panel with a cover or the like. It is desirable not to give pleasure.

  In a preferred embodiment of the display device of the present invention, the display device has at least two display panels, and the driving duty of one panel is appropriately set to select the scanning line selection voltage level and the voltage applied to the data line. Match the level. Thereby, the configuration of the voltage source circuit is simplified.

  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 switching the function appropriately according to the shape and size of the image display area and changing the drive duty, the voltage at the time of selecting the scanning line can be reduced, and the power consumption at the time of image display can be reduced. be able to.

  Prior to the description of the embodiments of the present invention, the contents of examination of the prior art made by the present inventors before the present invention will be described.

(1) Study made by the present inventor As shown in FIG. 44, the simple matrix type liquid crystal display device includes a first substrate having a plurality of scanning lines Y1 to Yn and a second substrate having a plurality of data lines X1 to Xm. The liquid crystal is sealed between the substrate and the Y driver (scanning line driving circuit) 4000 and the X driver (data line driving circuit) 5000 to drive each scanning line and each data line, and is positioned at the intersection of the scanning line and the data line. The display state of the pixel (display element) to be controlled is controlled 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 is the voltage level of the scanning line, and the right side is the voltage level of the data line.

Two voltage levels, V _A6 and V _A1 , are prepared as voltage levels when the scanning line is selected, and two voltage levels, V _A5 and V _A2 , are also prepared when the scanning line is not selected. On the other hand, regarding the voltage level of the data line, two positive voltage levels V _A4 and V _A6 and two negative voltage levels V _A1 and V _A3 are prepared. The positive and negative voltage levels are provided in liquid crystal display devices, where the polarity of the voltage applied to the scan line or data line is periodically inverted to prevent deterioration of the liquid crystal due to the application of DC voltage. It is necessary to make it.

  A driving waveform of the simple matrix type liquid crystal display device is shown in FIG. The upper side is the driving waveform of the scanning line, and the lower side is the driving waveform of the data line. From time t1 to time t2 and from time t4 to time t5 are pixel on periods, from time t2 to time t3, and after time t5 are pixel off periods.

  Focusing on the off-period of the pixels, in order to realize a state in which no image is displayed, the driving voltages of the scanning lines and the signal lines must be periodically inverted, and the amplitude thereof is 20 V or more.

  For example, a driving method in which the polarity of the driving voltage is inverted for each scanning line is adopted, and an image is displayed in the region “A” specified by the data line Y1 and the scanning lines X1, X2, X3, and X4 as shown in FIG. Is displayed, and the region “B” specified by the data lines Y2, Y3, Y4 and the scanning lines X1, X2, X3, X4 is not displayed. In FIG. 47, “+” and “−” indicate the polarity of the drive pulse.

  In order to bring the region “B” into the display-off state, the polarity of the drive pulse of the data lines Y2, Y3, and Y4 must be inverted for each scan line in accordance with the polarity of the drive pulse of the scan line. Understand. Therefore, the configuration of the voltage source circuit that generates the drive waveform is complicated and the power consumption is large, and the data line voltage and the scanning line voltage are constantly fluctuating, which is caused by the potential difference between the scanning line and the data line. 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-described problems, the driving method of the present invention prepares driving voltage levels for scanning lines and data lines as shown in FIGS. 1A and 1B, and FIG. As shown in FIG. 5, when the display is turned off (display off mode screen), the voltage levels of the scanning lines and the data lines are both fixed to Vc.

  Regardless of the polarity of the driving voltage of the scanning line and the data line, in the display off state (display off mode), the voltage level of the scanning line and the data line is always fixed to Vc, so that the configuration of the voltage source circuit is simplified. Power consumption can be reduced. Theoretically, since there is no potential difference between the scanning line and the data line, no unnecessary 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) in which one scanning line is selected one by one, the left side is a scanning line voltage level, and the right side is data. The voltage level of the line.

The voltage level when the scanning line is selected is V _MX1 and −V _MX1 , and the voltage level when not selected is only one 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 (in the case of FIG. 1B, four are simultaneously selected) in which a plurality of scanning lines are selected at the same time. Is the voltage level of the data line. There are two voltage levels V _X1 and −V _X1 when the scanning line is selected, and the voltage level of the scanning line when not selected is only Vc. On the other hand, there are five voltage levels of the data line: V _Y1 , V _Y2 , Vc, V _Y4 , and V _Y5 .

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

  In FIG. 2, the X driver 2 drives data lines D1, D2, D3, and D4, and the Y driver 4 drives scanning lines S1, S2, and S3. Pixels are arranged at the intersections of the scanning lines and the data lines to constitute the liquid crystal panel 6.

  For example, assuming that the liquid crystal panel 6 is used for a mobile phone, 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, the drive output of the X driver 2 and the Y driver 4 is fixed to Vc by setting the level of the display control signal DOFF to active (for example, L). Thereby, a display-off state with extremely low power consumption is realized.

  It should be noted that the Y driver 4 may display a display as long as all outputs of the Y driver are fixed to Vc even if a scanning pulse is selected for each scanning line or every plurality of scanning lines as usual. The off state is maintained. That is, as shown in FIG. 6, the liquid crystal does not change the transmittance unless it exceeds a predetermined threshold voltage (Vth), and the data line can be obtained only by inputting a selection pulse to the scanning line at the time of selection. This is because the threshold voltage is not exceeded as long as the voltage is Vc.

  By utilizing this fact, by appropriately controlling the voltage applied to each data line, not only the display of the entire surface of the liquid crystal panel 6 is turned off as shown in FIG. It is also possible to set the display off state (partial display off). The realization of the partial display off state will be described in detail in the following embodiments.

(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 display control mode in the device of FIG. 3A.

  The feature of the present embodiment is that the screen is vertically divided with the data line X160 as a boundary. As shown in FIG. 3B, the area 80 is used as an image display area, and the area 90 is not used for image display (display off state). Area) and dividing the screen by output control of a plurality of ICs for driving data lines.

  In FIG. 2, the entire display panel is in a display-off state (display-off screen), but for example, a display indicating how much a call can be made and a minimum display indicating the volume of the speaker, etc. even when the mobile phone is on standby. You may want to In this case, it is possible to minimize power consumption by securing only an area for performing minimum display and setting other areas in the display off mode (display off state).

  In FIG. 3A, reference numerals 10, 20, 30, and 40 are data line driving ICs, each responsible for driving 160 data lines. Two display control signals, DOFF (Display Off) 1 and DOFF2, are prepared. DOFF1 is input to the data line driving IC 10, and DOFF2 is input to the data line driving ICs 20, 30, and 40 in common.

  The display control signals DOFF1 and DOFF2 are both active at the low level. At this time, all of the drive outputs of the data line driving IC are the voltage level Vc 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 responsible for driving 120 scanning lines.

  When DOFF1 is set to “H” and DOFF2 is set to “L”, the drive outputs of the data line drive ICs 20, 30, and 40 (drive outputs of the data lines X160 to X640) are fixed to Vc. As a result, as shown in FIG. 3B, the area 90 in 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 performing a desired image display to the data lines X1 to X160. Further, the scanning line driving ICs 50 and 60, for example, sequentially select the scanning lines one by one. As a result, as shown in FIG. 3B, a predetermined display is made in the area 80 of the liquid crystal panel 70.

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

  Similarly to the first embodiment, since 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 of the voltage source circuit for creating the control voltage is also simple. Power consumption in the voltage source circuit is greatly 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 driver that selects a scanning line one by one. Note that reference numeral 130 in FIG. 4A is an OR gate.

  In the present embodiment, four display control signals DOFF0, DOFF1, DOFF2, and DOFF3 are prepared, and by controlling the voltage level of each control signal, as shown in FIG. You can choose.

  That is, when all display areas of the liquid crystal panel 70 are “A” as shown in FIG. 4B, when only DOFF0 is “L”, only the area “B” is in the display-off state. When both of DOFF0 and DOFF1 are “L”, the region “B” and the region “C” are in the display off state, and when DOFF0 to DOFF3 are “L”, the regions “B”, “C”, and “region” When “D” is in the display off state and all of DOFF0 to DOFF3 are “L”, the entire screen of the liquid crystal panel 70 including the region “E” is in the display off state.

(5) Fourth Embodiment Corresponding to setting a part of the area of the display panel to the display off mode, display data related to the area (image data indicating display off) and a clock for transferring the image data Also, the power consumption of the display device can be further reduced by stopping the operation. 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 the liquid crystal panel. This data line driving circuit is used in a driving method in which scanning lines are selected one by one, and has three voltage levels (V _MY1 , Vc as shown on the right side of FIG. 5 (FIG. 1A). , V _MY2 ) is output to the data line.

The circuit of FIG. 7A includes an operation timing controller 200, a data shift register 210 that temporarily stores data for driving data lines, a latch 220, a level shifter 230, and three voltage levels (V _MY1 , Vc, V _MY2 ). And a voltage selector 240 for selecting one of them. Reference numeral 250 is a liquid crystal panel.

  In FIG. 7A, XSCL indicates a clock for transferring data for driving the data line, LP is a pulse corresponding to the selection pulse, YD is a signal indicating the start of one frame period, and DATA is for driving the data line 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, wasteful power consumption can be prevented by stopping the data line drive data (DATA) and the transfer clock (XSCL) supplied to the operation timing controller 200 of FIG. 7A in correspondence with the start of the display off mode. . Note that even if only one of the data and the clock is stopped, the power consumption can be reduced. In particular, the transfer clock is a high-frequency signal, and the effect of stopping this clock is great.

  The data and the transfer clock are stopped, for example, under the control of a microcomputer that comprehensively controls the operation of the liquid crystal display device.

  FIG. 8A is a timing chart showing an operation when both the data and the clock are stopped corresponding to the start of the display off mode. In FIG. 8A, it is assumed that a part of the area of the liquid crystal panel is partially in the display off mode by two control signals (DOFF1, DOFF2) as in the example of FIG. 3A.

  When DOFF1 is “H” and DOFF2 is “L” as shown in FIG. 8A, data for 40 transfer clocks are supplied, but subsequent data transfer (and clock supply) is stopped.

  As shown in FIG. 8B, when both DOFF1 and DOFF2 become “H”, the partial display off mode is canceled, and accordingly, the stop of data and clocks is also released.

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

  FIG. 9 shows an example of a main configuration of a data line driver (X driver) for performing such display control. Although the circuit configuration is almost the same as that in FIG. 7A, a shift register having the same number of stages as the number of drive outputs, which temporarily stores display control data (DOFF) for each drive output, and an AND gate AD1, AD2 ... ADm is provided.

  The AND gates AD1, AD2,... ADm are provided corresponding to each drive output, and have a function of taking and outputting data line drive data (DATA) and 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 fixed value data is stored in the latch 220. When there is the fixed value data, the voltage selector 240 fixes the drive output level corresponding to the data to the above-described Vc. Thereby, the start position of the area to be in the display off mode can be freely set in units of drive outputs.

  10A and 10B are timing charts of an example in which the level of the display control signal DOFF2 is changed at an appropriate timing, the data transfer and the clock supply are stopped correspondingly, and the display off mode area is freely set. Indicates.

(7) Sixth Embodiment FIGS. 11 to 15 show other methods for determining an area to be in the display off mode.

  As shown in FIG. 11, various areas for the display off mode can be set in the display screen 270 by various combinations of the voltage levels of the four display control signals DOFF1 to DOFF4 as shown in FIGS. 12A to 12C. it can. In FIGS. 12A to 12C, the hatched area is the display off mode.

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

  Four decoders 300, 310, 320, and 330 are provided, and each of the display control signals DOFF1 to DOFF4 is input to each decoder.

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

  In this example, display control signals DOFF1 to DOFF4 are decoded by a decoder (DOFF POSITION DECORDER) 400, and control signals DX1 to DX4 of the decoders 300, 310, 320, and 330 are created.

  The decoder (DOFF POSITION DECORDER) 400 has a circuit configuration using two OR circuits 410 and 412 as shown in FIG.

(8) Seventh Embodiment When the display off-mode screen creation method described in the first embodiment is applied to a so-called multiline driving method (MLS driving method), a scanning line that is a feature of the MLS driving method is used. Combined with the effect of lowering the voltage level applied to the liquid crystal display, it is possible to further reduce the power consumption of the liquid crystal display device. Also, the display quality is improved.

  When the method for creating a display off mode screen described in the first embodiment is applied to a so-called multiline driving method (MLS driving method), the number L of simultaneously selected scanning lines may be an even number. Desirably, and more preferably, L is set to any one of 2, 4, 6, and 8. The reason will be described below. The outline of the multiline driving method will be described later.

  As shown in FIG. 16B, when the number of scanning lines simultaneously selected 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 always set to a symmetric voltage level on both the positive and negative sides with the “predetermined reference voltage level” as the center. Is done. This “predetermined reference voltage level” can be made to coincide with the voltage level of the scanning line when not selected.

  That is, when the number of scanning lines simultaneously selected is an even number, the voltage level at the center of the voltage levels of the data lines can be matched with the voltage level when the scanning lines are 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 facilitated, the circuit is not complicated, and it 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 employed. 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, five (L + 1) voltage levels of V _Y1 , V _Y2 , Vc, V _Y4 , and V _Y5 are prepared as voltage levels of the data line. V _Y1 and V _Y2 and V _Y4 and V _Y5 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 voltage of the scanning line and the data line may be fixed to Vc.

  When the scanning line simultaneous selection number “L” is an odd number, the number of voltage levels of the data line is an even number, 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 realizing the display off mode.

  As described above, it is desirable that the number L of simultaneously selected scanning lines in multi-line driving is 2, 4, 6 or 8.

  This is because if the number of scanning lines to be simultaneously selected is increased, the scale of the circuit for realizing the driving increases, which is contrary to the demand for lower power consumption. Therefore, it is realistic that the number L of scanning lines to be simultaneously selected is 2, 4, 6, and 8.

(9) Eighth Embodiment A. First Embodiment Device Configuration FIGS. 17 and 18 show a configuration example of a liquid crystal display device that employs the multiline driving method and can appropriately set an area to be in a display off mode.

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

  Upon receiving an instruction from the microprocessor (MPU) 2300, the DMA control circuit 2344 in the module controller 2340 accesses the video RAM (VRAM) 2320, reads out image data for one frame via the system bus 2420, The image data (DATA) is sent 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.

  Reference numeral 2400 is an input touch sensor, and reference numeral 2410 is a touch sensor control circuit. The input touch sensor 2400 and the touch sensor control circuit 2410 may be deleted when not necessary.

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

  The 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 of FIG. 18 will be described.

  In the liquid crystal display device of FIG. 17, multiline drive (MLS drive) control is performed using the module controller 2340, but in the liquid crystal display device of FIG. 18, a data line drive circuit (enclosed by a one-dot chain line in the figure). Is directly connected to the system bus 2420 of the microcomputer, and the MPU 2300 directly controls the MLS drive. The data line driver circuit includes an interface circuit 2440, a control circuit 2450, an oscillation circuit 2430, and the like. The display control signal (DOFF) is supplied to the control circuit 2450 via the interface circuit 2440. The display off mode area can be appropriately set according to the level of the display control signal (DOFF) as in the case of FIG.

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

  The voltage selector shown in FIG. 19 has the same configuration as that shown in FIG. That is, it has a shift register 256 that temporarily stores display control data (DOFF), and logic gates 404, 406, 408, 410, 412 and the like that receive the output of the MLS decoder 258 and the storage data of the shift register 256 as inputs. . Then, the opening and closing of the switches SW1 to SW5 is controlled by the output of each logic gate, and a desired voltage is applied to the data line of the liquid crystal panel 2250. Similar 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 MLS Driving Method Hereinafter, advantages and features of the MLS driving method will be described. By applying the display off mode screen creation method described in the first embodiment to the MLS driving method having the following features, the power consumption of the liquid crystal display device can be further reduced. In addition, display quality can be improved.

  The MLS driving method is a technique for simultaneously selecting a plurality of scanning lines in a simple matrix type liquid crystal panel such as an STN (Super Twisted Nematic) liquid crystal panel. Thereby, the drive voltage of the scanning line can be lowered.

  Further, as shown in the upper side 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. Luminance (transmittance) decreases. On the other hand, as shown in the lower side of FIG. 20, according to the MLS driving method, the interval between the selection pulses can be narrowed, so that the transmittance (brightness) of the liquid crystal panel is hardly decreased and the average transmittance is increased. Therefore, the contrast is also improved.

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

  The on pixel is “−1” and the off pixel is “+1”. Data indicating this on / off is stored in the frame memory. The selection pulse is represented by binary values “+1” and “−1”. Further, the driving voltage of the data line Y1 has three values “−V2”, “+ V2”, and “V1”.

  Which voltage of “−V2”, “+ V2”, and “V1” is applied to the data line Y1 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, in the case of FIG. 21B, d · β = + 2, and in the case of FIG. 21C, d · β. = + 2, and in the case of FIG. 21D, 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 drive voltage, and when “+2”, “+ V2” is selected, and “0” "V1" is selected.

  In the case where 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 corresponding data in 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”, “+ V2” is selected as the data line drive voltage. When the number of mismatches is “1”, “V1” is selected as the data line drive voltage. In the MLS drive that selects two lines simultaneously, the data line drive voltage is determined as described above, and the pixel is turned on / off by performing selection twice within one frame period. Since the selection period is provided a plurality of times, the decrease in the transmittance during the 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, with reference to FIG. 22, an operation in the case of driving a simple matrix liquid crystal display device by simultaneously selecting four scanning lines will be described in detail.

  Three (+ V1, 0, -V1) voltage levels are appropriately selected for the scanning lines in accordance with a scanning voltage pattern defined by a preselected orthogonal function system, and applied to the four scanning lines, respectively. It has become. An example of the scanning voltage pattern is 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 (one of the five voltage levels of -V3, -V2, 0, + V2, and + V3) determined by the number of mismatches is determined as data. It is applied to each data line by the line drive circuit. The procedure for determining the voltage level applied to the data line will be described below.

  The scanning voltage pattern is (+) when the selection voltage is + V1, (−) when the selection voltage is −V1 (−), the display pattern is data (+) when on display data, and (−) when data is off display. To do. The non-selection period does not consider the number of inconsistencies.

  In FIG. 22, a period necessary for displaying one screen is defined as one frame period (F), a period necessary for selecting all the scanning lines once is defined as one field period (f), and the scanning lines are defined as 1 A period necessary for selecting the number of times 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.

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

In the case of FIG. 22, the scanning pattern of 4 lines (X1 to X4) selected in the first selection period (H _1st ) in the first field period f _1st is set in advance as shown in FIG. Therefore, it is always (++-+) regardless of the state of the display screen.

  Here, considering the case of performing full-on display, the display in the first column corresponding to (pixel (X1, Y1), pixel (X2, Y1), pixel (X3, Y1), and pixel (X4, Y1)). The pattern is (++++). When both patterns are compared in order, the first, second and fourth have the same polarity, and the third has a different polarity. That is, the number of mismatches is “1”. When the number of mismatches is “1”, −V2 is selected from five voltage levels (+ V3, + V2, 0, −V2, −V3). Thus, in the case of the scanning lines X1, X2 and X4 in which + V1 is selected, the voltage applied to the liquid crystal element is increased by the selection of -V2, while in the case of the scanning line X3 in which -V1 is selected. In this case, the voltage applied to the liquid crystal element is lowered by the selection of -V2.

  The voltage applied to the data line in this way corresponds to the “vector weight” at the time of orthogonal transformation, and a true display pattern can be reproduced by adding all the weights to the four scan patterns. The voltage level is set as follows.

  Similarly, -V3 is selected when the number of mismatches is "0", 0 level is selected when the number of mismatches is "2", + V2 is selected when the number of mismatches is "3", and + V3 is selected when the number of mismatches is "4". To do. V2 and V3 are set so that the voltage ratio is (V2: V3 = 1: 2).

  In the same procedure, for the four scanning lines X1 to X4, the number of mismatches of the data line columns Y2 to Ym is determined, and the data of the obtained selection voltage is transferred to the data line driving circuit. The voltage determined by the above procedure is applied during the selection period.

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

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

  When the voltage waveform applied to the data line (Y1) when the entire surface is on is determined according to the above procedure, the voltage waveform applied to the pixel (X1, Y1) is as shown in FIG. It becomes like (c) of 22.

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

(10) Ninth Embodiment In the present embodiment, a case will be described in which the boundary position between a screen not used for image display and a screen on which display is performed is controlled on the Y side (scan line side) of the display panel. .

  That is, as shown in FIG. 24A, the display control signals DOFF3 and DOFF4 are also input to the scanning line drive circuits 50 and 60. For example, as shown in FIG. 24B, the screen of the liquid crystal panel 70 is used for image display. 82 and an area 84 not used for image display.

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

As a result, the size of the display panel is substantially changed, and the drive duty 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 duty change.

  In the example of FIG. 25, since the driving duty is ½, the voltage supplied from the variable voltage source 510 to the scanning line driving circuit may be about half.

  On the other hand, an area 504 that is 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 i1 flows to charge the capacitor C _O. As a result, the voltage across the capacitor _CO becomes V1.

  Next, when the transistor Q2 is turned off, the current i2 flows, the transistor Q1 is turned on, 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. 510 shows a configuration of a liquid crystal display device adopting the MLS driving method for realizing the driving method of the present embodiment. The MLS controller 2340 changes the output voltage of the variable voltage source 510 according to the control signal V _CON in accordance with the display control by the display control signals DOFF3 and DOFF4.

(11) Tenth Embodiment In the present embodiment, the image size is increased without changing the drive duty. That is, processing for converting the resolution of the image is performed. Hereinafter, this process will be described with reference to FIGS. 28A to 28C.

  As shown in FIG. 28A, the display panel 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 in the display area “B”. It is assumed that the Y driver 530 is responsible for driving the scanning lines.

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

  The configuration of the main part of the scanning line driving circuit in the liquid crystal display device using MLS driving for realizing the processing for doubling the image size (resolution is ½) without changing the driving duty as described above An example is shown in FIG. Also, FIGS. 30A and 30B specifically show the conditions of the respective parts when performing the display as shown in FIG. 28B and when performing the double-angle display as shown in FIG. 28C.

  29 has input terminals 1A, 2A,... 8A and input terminals 1B, 2B,. Each input terminal receives data D0, D1, D2, or D3 as shown. Data D0, D1, D2, and D3 are data that determine voltages to be applied to the scanning lines.

  When the control signal B0 is “L”, the data input to the terminals 1A, 2A... 8A is output to the output terminals 1Y, 2Y. On the other hand, when the control signal B0 is “H”, the data input to the terminals 1B, 2B... 8B is output to the output terminals 1Y, 2Y.

  On the other hand, one input terminal of the two-input AND gates 610 to 617 is connected to each output terminal 1Y, 2Y,. The enable control signal EN1 is input to the other input terminals of the 2-input AND gates 610 to 613, and the enable control signal EN2 is input to the other input terminals of the 2-input AND gates 614 to 617.

  When performing 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”. Accordingly, data D0, D1, D2, and D3 are output to the output terminals OUT1 to OUT4 of the two-input AND gates 610 to 614 in FIG. 29, respectively, and the voltages of the four scanning lines are determined based on each data. .

  On the other hand, when the double-angle display as shown in FIG. 28C is performed, 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”. To do. Thereby, data D0, D0, D1, D1, D2, D2, D3, and D3 are output to the output terminals OUT1 to OUT8 of the two-input AND gates 610 to 617 in FIG. The scan line voltage is determined. 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 is doubled, but if a similar method is used, the image size can be increased by 4 times, 8 times, or the like. In either case, the display is increased in impact such as icon display on the liquid crystal panel user with low power consumption equivalent to the case where a part of the screen is partially turned off. There is an effect to impress.

(12) Eleventh Embodiment In the ninth embodiment, the boundary position between a screen not used for image display and a screen on which display is performed is displayed on the Y side (scanning) of the display panel with reference to FIGS. The display control method when controlling on the line side) has been described. However, in this method, since the driving duty changes, a variable voltage source is required.

  In the present embodiment, the same display control is performed without changing the driving duty.

  As shown in FIG. 31, in the present embodiment, all the scanning lines S1 to S6 are selected without changing the driving duty “N”.

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

  Now, consider the six pixels M1 to M6 along the data line L1, consider turning on the pixels M1 to M3, and turning off the pixels M4 to M6. If the pixels M4 to M6 are simply turned off, the voltage level of the data line L1 may be fixed to the above-described Vc (voltage when the scanning line is not selected) when the scanning lines S4 to S6 are selected. The display of the pixels M1 to M3 becomes extremely dark and proper display cannot be performed. This is because in the display device, the circuit is designed on the assumption that a voltage for performing a predetermined display (voltage for performing on / off display) is always applied to the data line L1. That is, continuously applying the voltage level Vc when the scanning line is not selected to the data line L1 is a nonstandard driving method.

  Therefore, in the present embodiment, at the timing when the scanning lines S4, S5, and S6 should be selected, the voltage Vc at the time of non-selection is applied to the scanning line, while the normal on / off display is performed on the data line L1. One of the voltages to be applied when performing the above is applied. As a result, the display of the pixels M1, M2, and M3 can be appropriately maintained, and the pixels M4, M5, and M6 can be brought into a display-off state. At this time, in the area 504 in the display-off state, the voltage level of the scanning line is fixed to Vc and polarity inversion is not performed, so that a voltage for displaying on the data line is applied. The power consumption is reduced.

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

  FIG. 32 is a timing chart showing an operation when the driving method of the present embodiment is applied to the MLS driving method for simultaneous selection of 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 image display is appropriately performed, and a period from time t2 to t3 is a period during which display is turned off. In 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 lines instead of “Vc”. Understand.

FIG. 33 shows the configuration of a liquid crystal display device that employs the MLS driving method and performs the operation shown in FIG. Unlike the display device of FIG. 27, a fixed voltage source 512 is provided. Further, the MLS controller 2340 sends display control signals DOFF3 and DOFF4 to fix the scanning line drive output to Vc, and sends a control signal V _XC in accordance with this to output the X drivers 520 and 530. _Is fixed to a predetermined voltage (for example, V _Y4 shown in FIG. 32).

(13) Twelfth Embodiment FIGS. 34A and 34B show the configuration of the main part of a liquid crystal display device of the present embodiment. A feature of this embodiment is that, when a screen is in a display-off state, at least one of the scanning lines and the data lines is in a potential floating state (high impedance 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. The conductor layers 800 and 820 are constituent materials for the scanning lines and 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, electric charge is injected from the conductor layer 800 or the conductor layer 820 to the liquid crystal 810 due to a potential difference between the conductor layer 800 and the conductor layer 820. Occurs and current flows. This current is a wasteful current.

  Therefore, as shown in FIG. 34B, switches 711 and 726 are provided in the voltage application path to the conductor layers 800 and 820, and at least one of the switches 711 and 726 is opened in the high impedance mode. is there. As a result, the current path is interrupted and no useless current flows. Thereby, power consumption can be reduced.

  However, since the scanning line or the data line is unstable due to a potential floating state, an undesired 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 or the data line is in a potential floating state, it is desirable to cover the screen with a cover so as not to cause discomfort to the user of the liquid crystal panel.

  In the liquid crystal panel of FIG. 34A, the switches 711 to 716 in the switch unit 710 and the switches 721 to 726 in the switch unit 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. A cover 750 covers the screen.

  In a liquid crystal display device employing the MLS driving method, a configuration for realizing a mode (high impedance mode) in which display is prohibited by setting the potential of the data line to a floating state is shown in FIGS.

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

  An example of a specific configuration of the multiline decoder 860 and the voltage selector 870 is shown in FIG.

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

  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 open, and the data line is in a floating state in terms of potential. As a result, the display screen enters a high impedance mode.

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

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

Then, 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 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 the two panels 910 and 920 display images by the MLS driving method. In FIG. 37, an X driver (X1) 940, an X driver (X2) 942, and a Y driver (Y1) 960 are provided for driving the first display panel 910. An X driver (X3) 944, an X driver (X4) 946, a Y driver (Y2) 962, and a Y driver (Y3) 964 are provided to drive the second display panel.

  The first display panel 910 is, for example, a dedicated panel for performing simple icon display, and the second panel 920 is a general-purpose panel for performing various other displays. 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 an icon, and therefore paying attention to the fact that there is no problem even in a narrow and small display area, the duty of driving the first display panel 910 is reduced, This is because the voltage level supplied to the X driver 940 and the voltage level supplied to the Y driver 960 are designed to match.

That is, as shown on the right side of FIG. 1B, when the MLS driving method is employed, the scanning line selection voltage level V _X1 (−V _X1 ) and the data line selection voltage level V _Y5 (V _Y1 ) match. Usually not. However, for example, when the number of scanning lines simultaneously selected is h = 4 and the threshold voltage Vth of the liquid crystal is VV = 2.0 V, if the number of scanning lines of the first display panel 910 is 16, V _X1 and V _Y5 Each level of 3.27V matches.

  In this way, 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. In the display device of FIG. 37, this is utilized to simplify the configuration of the voltage source 930 and reduce power consumption. As a result, the icon can be displayed with low power consumption.

  In addition, various kinds of display can be performed using the second display panel 920.

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

  Then, 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 scanning line selection is reduced, and the power consumption at the time of image display is reduced.

  This will be specifically described with reference to FIG. In FIG. 38, an area 912 is an area (display area) used for image display, and an area 922 is an area not used for image display (area in display off mode).

  Currently, it is assumed that the driver 941 functions as a data line driver (X driver), and the driver 961 and the driver 963 function as scanning line drivers (Y drivers).

  Here, attention is focused on the shape of the display area 912. The display area 912 has a vertically elongated shape. That is, the length is long and the width is short. 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 drivers). As a result, the number of scanning lines (driving duty) decreases, and the selection voltage level of the scanning lines can be lowered by the amount that the duty is reduced. Thereby, the power consumption of the display device can be reduced.

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

  FIG. 39A shows an external appearance of the mobile phone during normal use, and FIG. 39B shows an external appearance when the mobile phone is used as a portable terminal.

  The mobile phone includes a screen 1000 and a screen 1010, an antenna 1100, a touch key 1200, a microphone 1300, and a panel 1400. Screen 1000 and screen 1010 constitute one liquid crystal display panel.

  As apparent from FIGS. 39A and 39B, the screen 1010 is hidden under the panel 1400 during normal use. Accordingly, during normal use, the screen 1010 is in a display off mode or a high impedance mode.

  And when using as a portable terminal, as shown to FIG. 39B, the panel 400 is turned down and the screen 1010 appears. In this state, the display off mode or the high-impedance mode for the screen 1010 is cancelled, and thus various image displays using the screen 100 and the screen 1010 are possible.

  40A and 40B are diagrams showing how the portable electronic dictionary is used.

  The portable electronic dictionary 1500 is normally used in a form as shown in FIG. 40A, and at this time, a desired display is made using the screen 1510.

  When the screen 1510 is insufficient, the screen 1520 is pushed upward as shown in FIG. 40B, and the image display area is enlarged. In the state of FIG. 40A, since the screen 1520 is hidden behind the main body and cannot be seen, the display off mode or the high impedance mode is set.

  41A and 41B are views each showing an external appearance of a portable electronic device.

  The portable electronic device in FIG. 41 includes a frame body 1600, a display panel 1620, and a cover 1610. The cover 1610 can be slid to the left and right, whereby the size of the display area can be appropriately changed and the display screen can be divided. The area of the display panel that is hidden under the cover 1610 and is not visible is in the display off mode or the high impedance mode.

  In FIG. 41B, two covers 1612 and 1614 are provided. Each cover can be slid left and right, and the size of the display area can be changed appropriately. An area of the display panel 1622 that is hidden under the covers 1612 and 1614 is in a display off mode or a high impedance mode.

  FIG. 42A and FIG. 42B are diagrams showing usage patterns of the portable electronic translator.

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

  Screens hidden behind the covers 1612 and 1614 in the display panel are in the display off mode or the high impedance mode.

  In the mobile phone of FIG. 43, the display screen of the display panel is divided into an area “A” and an area “B”, and a simple image such as an icon is displayed in the area “A”. Is set to display off mode or high impedance mode.

  In the above electronic apparatus, a desired image display can be performed with extremely low power consumption by partially setting an area that does not contribute to display to a display off mode or a high impedance mode.

FIG. 1A is a diagram showing an example of voltage levels of scanning lines and data lines in the driving method of the display device of the present invention, and FIG. 1B is a diagram showing another example of voltage levels of scanning lines and data lines. . It is a figure for demonstrating the principle of the drive method of the display apparatus of this invention. FIG. 3A is a diagram showing an example of the configuration of a simple matrix type liquid crystal display device adopting the driving method of the present invention, and FIG. 3B is a diagram showing an example of the display screen of the device of FIG. 3A. 4A is a diagram showing another example of the configuration of a simple matrix type liquid crystal display device adopting the driving method of the present invention, and FIG. 4B is a diagram showing an example of the display screen of the device of FIG. 4A. It is a figure which shows the voltage level of the scanning line and data line in this invention at the time of employ | adopting the drive method (ATP drive method) which selects a scanning line one by one. It is a figure which shows the relationship between the applied voltage and 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 adopting the driving method of the present invention, and FIG. 7B is a timing chart for explaining characteristic operations in the device of FIG. 7A. FIG. 8A is a timing chart showing an example of the operation of the liquid crystal display device of FIG. 7A, and FIG. 8B is a timing chart showing another example of the operation. It is a figure which shows the structural example of the simple matrix type liquid crystal display device which employ | adopted the drive method of this invention. FIG. 10A is a timing chart showing an example of the operation of the liquid crystal display device of FIG. 9, and FIG. 10B is a timing chart showing another example of the operation. It is a figure which shows the structural example of the liquid crystal display device of this invention. FIG. 12A, FIG. 12B, and FIG. 12C are diagrams each showing a display control mode in the liquid crystal display device of FIG. It is a figure which shows an example of a structure of the principal part of the liquid crystal display device of this invention. It is a figure which shows the other example of a structure of the principal part of the liquid crystal display device of this invention. The concrete circuit structure of the decoder in FIG. 14 is shown. FIG. 16A is a diagram showing the voltage levels of the scanning lines and data lines when four scanning lines are simultaneously selected and driven, and FIG. 16B shows the relationship between the number of simultaneous selections and the number of voltage levels of the data lines. FIG. It is a figure which shows an example of a structure of the liquid crystal display device of this invention which employ | adopted the multi-line drive method. It is a figure which shows the other example of a structure of the liquid crystal display device of this invention which employ | adopted the multiline drive method. It is a figure which shows an example of a structure of the principal part in the liquid crystal display device of FIG. It is a figure for demonstrating the characteristic of the multi-line drive method. It is a figure for demonstrating the characteristic of operation | movement of a multiline drive method. It is a figure which shows the example of a change of the voltage of a scanning line, a data line, and a pixel part in the liquid crystal display device which employ | adopted the multiline drive method. FIG. 23A and FIG. 23B are diagrams showing examples of scanning voltage patterns in the multiline driving method. 24A is a diagram showing an example of the configuration of the liquid crystal display device of the present invention (configuration in the case where screen control is performed along the scanning line arrangement direction), and FIG. 24B is a display control in the liquid crystal display device of FIG. 24A. It is a figure which shows the aspect of. It is a figure which shows the specific example of the display control in the liquid crystal display device of this invention. FIG. 26 is a diagram showing an example (bootstrap circuit) of a specific configuration of the variable voltage source shown in FIG. 25. FIG. 27 is a diagram showing a configuration example of a liquid crystal display device adopting a multi-line driving method for realizing the display control shown in FIG. 28A shows a screen on which no image is displayed, FIG. 28B shows a state in which an image is displayed on a half screen, and FIG. 28C shows a state in which the display image in FIG. Display state). It is a figure which shows the structure of the circuit for performing the resolution conversion shown by FIG. 28B and FIG. 28C. 30A and 30B are diagrams for explaining the operation of the circuit shown in FIG. It is a figure which shows the specific example of the display control in the liquid crystal display device (apparatus which employ | adopts a multi-line drive method) of this invention. FIG. 32 is a timing chart for explaining the operation of the apparatus of FIG. 31. FIG. FIG. 32 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 showing an example of a main part configuration of the liquid crystal display device of the present invention, and FIG. 34B is a diagram for explaining the characteristics of the configuration of FIG. 34A. It is a figure which shows the principal part structure at the time of applying the display control shown by FIG. 34A and FIG. 34B to the liquid crystal display device which employ | adopts a multiline drive method. FIG. 36 is a diagram showing a more specific circuit configuration of the configuration of FIG. It is a figure which shows the structural example of the liquid crystal display device of this invention. It is a figure which shows the structural example of the liquid crystal display device of this invention. FIG. 39A is a front view of the mobile phone equipped with the display device of the present invention during normal use, and FIG. 39B is a front view of the mobile phone of FIG. 39A during special use. 40A and 40B are perspective views of a portable electronic dictionary on which the display device of the present invention is mounted. FIG. 41A and FIG. 41B are diagrams each showing an external shape of an electronic apparatus equipped with the display device of the present invention. 42A and 42B are perspective views of a portable electronic translator equipped with the display device of the present invention. It is a figure which shows the external shape of the mobile telephone carrying a display apparatus. It is a figure which shows the main structures of a normal simple matrix type liquid crystal display device. It is a figure which shows the voltage level of the scanning line and data line in the drive method of the conventional liquid crystal display device. 5 is a timing chart for explaining the operation of a normal simple matrix type liquid crystal display device. It is a figure which shows the problem of the drive method of the conventional liquid crystal display device.

Explanation of symbols

2,100,110,280,5000 X driver (signal line drive circuit),
4, 20, 520, 530, 4000 Y driver (scanning line drive circuit),
6,70 liquid crystal panel, 10-40 data line drive 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 LCD panel, 252 frame memory, 256 shift register,
258 MLS decoder, 270 display screen, 280 X driver,
290 Y driver, 300-330 decoder, 340-370 voltage selector,
400 decoder, 404-412 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 circuits,
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 scan line driver, 1000,1010 screen,
1100 antenna, 1200 touch sensor, 1300 microphone,
1400 panel, 1500 portable electronic dictionary, 1510, 1520 screen,
1600 frame, 1610, 1612, 1614 cover, 1620 display panel,
1700 portable electronic translator, 1710, 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,
2340 MLS controller, 2342 control signal generation circuit,
2344 DMA control circuit, 2400 touch sensor for input,
2410 touch sensor control circuit, 2420 system bus,
2430 oscillation circuit, 2440 interface circuit, 2450 control circuit

Claims (3)

A plurality of scanning lines; a plurality of data lines; a plurality of display elements arranged in accordance with intersections of the scanning lines and the data lines; a scanning line driving circuit for driving the plurality of scanning lines; A data line driving circuit for driving a plurality of data lines,
A plurality of voltage levels applied to the data line are prepared,
The data line driving circuit includes a decoder to which a control signal instructing prohibition of display and a display control signal instructing an off state of display are input, and a voltage output to each data line from the plurality of voltage levels A switch circuit for selecting
The decoder includes: a first logic gate for decoding image data and the display control signal; a second logic gate for decoding the control signal and outputs of the first logic gate; Have
A display device, wherein the switch circuit is opened by forcibly fixing the output of the second logic gate based on the control signal, and the potential of the data line is set in a floating state. In claim 1,
The scanning line driving circuit selects the plurality of scanning lines simultaneously, and applies a scanning voltage based on a predetermined selection voltage pattern to each of the scanning lines.   An electronic apparatus comprising the display device according to claim 1.

Images