CN1322358C

CN1322358C - Display and its drive method

Info

Publication number: CN1322358C
Application number: CNB011331747A
Authority: CN
Inventors: 米田清; 横山良一
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2000-09-18
Filing date: 2001-09-18
Publication date: 2007-06-20
Anticipated expiration: 2021-09-18
Also published as: KR100481108B1; CN1345023A; TWI249632B; KR20020022036A; JP5004386B2; JP2002162948A

Abstract

The present invention provides a display device and its driving method to prevent the occurrence of erroneous writing of data into a holding circuit 110, to reduce power consumption and to provide highly integrated display pixels. In a display device which is provided with holding circuits to sustain digital video data for display pixels, the power supply voltage supplied to the holding circuits 110 is set to a minimum level that is an absolute minimum for sustaining the data. The power supply voltage to be supplied to the circuits 110 is boosted by a boosting circuit 95 after completion of the writing. In accordance with the signals inputted from gate signal lines 51, digital video signals from drain signal lines 61 are written into the circuits 110 and the circuits 110 sustain the signals. Displaying is conducted in accordance with the signal sustained in the circuits 110.

Description

Display device and driving method thereof

Technical field

The present invention relates to display device and driving method thereof, particularly be applicable to the display device and the driving method thereof of portability display device.

Background technology

In recent years, the portable display device of market demand is for example carried TV, portable phone etc.According to such needs, actively carrying out and the miniaturization of display device, in light weight, the low corresponding research and development of consumed power.

Fig. 7 represents the circuit diagram of a display pixel of the liquid crystal indicator of conventional example.On insulativity substrate (not shown), intersect to form signal line 51, drain signal line 61, the TFT65 that is connected with two

signal wires

51,61 is set near its cross part.The source electrode 11s of TFT65 is connected to the show electrode 80 of liquid crystal 21.

In addition, the auxiliary capacitor 85 that the voltage that makes show electrode 80 keeps 1 field interval is set, a terminal 86 of this auxiliary capacitor 85 is connected with the source electrode 11s of TFT65, and applies the public current potential of each display pixel on another electrode 87.

Here, when signal line 51 was applied sweep signal, TFT65 became conducting state, from drain signal line 61 analog picture signal was sent to show electrode 80, and was kept by auxiliary capacitor 85.The picture signal that applies on the show electrode 80 is applied on the liquid crystal 21, liquid crystal 21 is orientated, can obtain liquid crystal display by this voltage.

Therefore, can obtain to show and irrelevant with dynamic image, still image.Under situation about rest image being presented on such liquid crystal indicator, the battery parameter that the image that for example shows dry cell on the part of the liquid crystal display part of portable phone is used as being used to driving portable phone shows.

But, identical even under the situation that shows rest image in the liquid crystal indicator of above-mentioned formation with the situation that shows dynamic image, make TFT65 become conducting state with sweep signal, picture signal need be write each display pixel again.

Therefore, because being in, the outside LSI that produces the driving circuit of drive signals such as sweep signal and picture signal and produce the various signals of the work timing that is used for control Driver Circuit often works, so consume very large power.Therefore, in only being furnished with power-limited portable phone, there is short such shortcoming of its up time.

To this, open the liquid crystal indicator that has disclosed in the flat 8-194205 patented claim each display pixel configuring static type storer (Japan) spy.The part of quoting this communique below illustrates, as shown in Figure 8, this liquid crystal indicator by with 2 grades of phase inverter INV1, INV2 as the storer of positive feedback form, be about to the holding circuit of static type storer as data image signal, thereby reduce consumed power.

Here, according to the diadic data image signal that keeps in the static type storer, the resistance value between on-off element 24 control line of reference Vref and the show electrode 80, the bias state of adjustment liquid crystal 21.On the other hand, AC signal Vcom is input to common electrode.Ideally, come modified-image if resemble the rest image, this device does not need the renewal to storer.

As mentioned above,, be fit to show the rest image of low key tone degree, and reduce consumed power at the liquid crystal indicator of being furnished with the static type storer that is used for keeping data image signal.

But there is following problem in the liquid crystal indicator of said structure.Below with reference to Fig. 9 this problem is described.Now, suppose that the source electrode 11s of pixel selection TFT65 is ' L (low) ' level, keep ' H (height) ' level on the output node of phase inverter INV1.

By external circuit ' H ' outputed to drain signal line 61 from this hold mode, ' H ' is written under the situation of static type storer, because the N channel-type TFT conducting of phase inverter INV2, so as shown in phantom in FIG., come streaming current along the path of drain signal line 61 → TFT65 → N channel-type TFT.That is, cause ' H ' level and ' extension of L ' level converges, and misses the danger that writes because of the decline of ' H ' produces.

Here, in order normally to write the data of ' H ', the source electrode 11s voltage of TFT65 need satisfy the high such condition of threshold voltage than phase inverter INV1, but owing to have above-mentioned current path, so the danger that the source electrode 11s voltage of TFT65 descends.

Therefore, in order to satisfy above-mentioned condition, following countermeasure is arranged.

1. improve from external circuit drain signal line 61 supplied with ' voltage of H ' level.

Voltage when 2. improving selection signal line 51 or the channel width of increase TFT65 are so that reduce the conducting resistance of pixel TFT 65.

But, 1. exist because of the supply voltage of the external circuit such shortcoming of power that increases consumption that rises.2. exist supply voltage rising, the TFT size of gate drivers to increase, be difficult to come the such shortcoming of Butut with the fine pitch of pixel.

Summary of the invention

The present invention is used for keeping providing the data mistake that prevents this static type storer to write in the display device of static type storer of data image signal at display pixel comprising, and can make consumed power low and carry out the display device of the fine Butut of pixel.

In the application's invention disclosed, following content is described mainly.

Promptly, the 1st formation of the present invention is: a kind of display device, comprise along a plurality of signal lines of a direction configuration on the substrate, with along and a plurality of drain signal line of disposing of the described signal line direction of intersecting, by selecting from the sweep signal of described signal line and being rectangular configuration from the display pixel that described drain signal line is supplied with picture signal, it is characterized in that, comprise: holding circuit, write data image signal according to signal, and keep this data image signal from described drain signal line from the input of described signal line; And booster circuit, after the writing of described data image signal, the supply voltage of supplying with described holding circuit is boosted, show according to the output of described holding circuit.

According to such formation, owing to reduce the degree that can keep data image signal that is set to writing the fashionable supply voltage of supplying with on can be with holding circuit, and can improve the degree that obtains good image that is set to during the demonstration after writing, so can prevent from the mistake of the data image signal of this holding circuit is write, and realize that consumed power is low.

In addition, according to said structure, owing to can reduce the pixel selection element, so can carry out the fine Butut of pixel.

In said structure, constitute by the two-stage inverter circuit of described holding circuit by positive feedback, can make the circuit component number reach Min..In addition, inverter circuit is CMOS type phase inverter preferably, so that consumed power is low.

In said structure, comprise according to the output of described holding circuit and select signal selecting circuit that this signal selecting circuit is made of a plurality of thin film transistor (TFT)s that will be applied to from the signal of described holding circuit on the grid to the show electrode signal supplied.This is because can carry out the demonstration corresponding with the output of holding circuit, and reduces the circuit elements number of packages of signal selecting circuit.

And in said structure, the supply voltage that is boosted by described booster circuit is added in the voltage of signals height of supplying with described show electrode than the threshold voltage with described thin film transistor (TFT).Thus, signal supplied descends on the show electrode owing to prevent to make, and shows so can obtain good, the second best in quality image of contrast.

The driving method of display device of the present invention, wherein said display device comprises: along a plurality of signal lines of a direction configuration on the substrate, the a plurality of drain signal line that dispose along the direction of intersecting with described signal line, by select and supply with the display pixel that is rectangular configuration of picture signal from the sweep signal of described signal line from described drain signal line, in described display pixel, write from the data image signal of described drain signal line and keep the holding circuit of this data image signal according to signal from the input of described signal line, and the booster circuit that boosts of the supply voltage that will supply with described holding circuit, wherein, this display device shows according to the output of described holding circuit, the driving method of described display device is characterised in that: according to the signal from described signal line input, after will writing described holding circuit from the data image signal of described drain signal line, the supply voltage that to be supplied with described holding circuit by described booster circuit boosts, and carries out the image corresponding with described data image signal and shows.

Constitute according to this, can prevent from the mistake of the data image signal of this holding circuit is write, and realize that consumed power is low.

Description of drawings

Fig. 1 is the circuit structure diagram of the liquid crystal indicator of the present invention the 1st embodiment.

Fig. 2 is the circuit structure diagram of the booster circuit of the present invention the 1st embodiment.

Fig. 3 is the circuit structure diagram of the picture signal commutation circuit of the present invention the 1st embodiment.

Fig. 4 is the sequential chart of the liquid crystal indicator of the present invention the 1st embodiment.

Fig. 5 is the sectional view of reflection-type liquid-crystal display device.

Fig. 6 is the circuit structure diagram of the EL display device of the present invention the 2nd embodiment.

Fig. 7 is the circuit structure diagram of the liquid crystal indicator of conventional example.

Fig. 8 is another circuit structure diagram of the liquid crystal indicator of conventional example.

Fig. 9 is the circuit diagram of problem points of the liquid crystal indicator of explanation conventional example.

Embodiment

The following describes embodiments of the invention.Fig. 1 represents the circuit structure diagram of the liquid crystal indicator of the 1st embodiment.

A plurality of signal lines 51 that the direction configuration is connected with the gate drivers 50 of supplying with sweep signal in insulated substrate 10 upper edges, the edge disposes a plurality of drain signal line 61 with the direction that these signal lines 51 intersect.

According to timing from the sampling pulse of drain driver 60 output, sampling transistor SP1, SP2 ..., the SPn conducting, the data-signal (analog picture signal or data image signal) of data signal line 62 is supplied with drain signal line 61.

Liquid crystal display panel 100 is by constituting according to a plurality of display pixels 200 rectangular configurations of selecting and supply with from the data-signal of drain signal line 61 from the sweep signal of signal line 51.

Below, the detailed structure of display pixel 200 is described.Near the cross part of signal line 51 and drain signal line 61, the circuit selection circuit 40 that P channel-type TFT41 and N channel-type 42 constitute is set.TFT41, two drain electrodes of 42 are connected to drain signal line 61, and their two grids are connected to circuit selection signal line 88.TFT41,42 makes wherein some conductings according to the circuit selection signal from circuit selection signal line 8.In addition, the circuit selection circuit 43 of selecting circuit 40 to form in pairs, be made of P channel-type TFT44 and N channel TFT 45 with circuit described later is set.

Thus, can select to switch simulation display mode described later (corresponding full color dynamic image) and digital display mode (consumed power is low, corresponding rest image).In addition, select the circuit 40 adjacent pixel selection circuit 70 that dispose N channel-type TFT71 and N channel-type TFT72 formation with circuit.TFT71,72 selects the TFT41,42 of circuit 40 to be connected in parallel with circuit respectively, and their two grids connect signal line 51.TFT71,72 makes both conductings simultaneously according to the sweep signal from signal line 51.

In addition, be provided for keeping the auxiliary capacitor 85 of analog picture signal.An electrode 86 of auxiliary capacitor 85 is connected to the source electrode 11s of TFT71.Another electrode 87 is connected to public auxiliary capacitance line 81, supplies with bias voltage V _SCThe grid of TFT71 is opened, and when being applied to analog picture signal on the liquid crystal 21, this signal demand keeps 1 field interval, but only this voltage of signals can the decline gradually along with the time on liquid crystal 21.So, may present and show irregular and can not obtain good demonstration.Therefore, be provided for this voltage is kept the auxiliary capacitor 85 of 1 field interval.

Between this auxiliary capacitor 85 and liquid crystal 21, the P channel-type TFT44 that circuit is selected circuit 43 is set, have the structure of selecting the TFT41 conducting simultaneously of circuit 40 to end with circuit.In addition, between the show electrode 80 of the TFT72 of pixel selection circuit 70 and liquid crystal 21, holding circuit 110, signal selecting circuit 120 are set.

Holding circuit 110 is made of 2 inverter circuits of positive feedback, constitutes the static type storer that keeps the diadic numeral.Here, for consumed power is low, the CMOS type inverter circuit that the preferably quiet current sinking of inverter circuit is little.

Signal selecting circuit 120 is circuit of selecting signal according to the signal that comes self-hold circuit 110, is made of 2 N channel-type TFT121,122.Because in the future the output signal of the complementation of self-hold circuit 110 is applied to respectively on TFT121,122 the grid, so TFT121,122 conducting complementally ends.

Here, select AC driving signal (signal B) during the TFT122 conducting, and select opposite electrode signal VCOM (signal A) during the TFT121 conducting, select circuit 43 to supply with by circuit voltage is applied to show electrode 80 on the liquid crystal 21.

When digital display mode, one vertical during between carry out full spot scan, will write holding circuit 110 from the data image signal of drain electrode signal wire 61.Here, during writing, data are set at the required minimum voltage (for example 3V) of holding circuit 110 maintenance data with constituting the supply voltage VDD that supplies with on 2 inverter circuits of holding circuit 110, and after data write end, the data that keep in based on holding circuit 110 show during (demonstration of rest image), boost to more high voltage.

At this moment, supply voltage VDD preferably boosts to than the high voltage of voltage that adds TFT121,122 threshold voltage (Vt) gained on the ceiling voltage of signal A, B.That is, satisfy the such relation of VDD＞Vt+max (signal A, signal B).As this VDD, more suitable about 8V.Do not satisfying under the situation of this relation, signal A, B level can not supplied with show electrode 80 by TFT121,122 with descending and charge the contrast deterioration of liquid crystal display.

Below, the peripheral circuit of liquid crystal screen 100 is described, on the tyre circuit substrate 90 different, screen board is set drives and use LS191 with the insulativity substrate 10 of liquid crystal screen 100.With LSI91 vertical enabling signal STV is input to gate drivers 50 from the screen board driving of this tyre circuit substrate 90, horizontal enabling signal STH is input to drain driver 60.In addition, picture signal is input to data line 62.

In addition, be provided on the charged outside base board 90 and will constitute the booster circuit 95 that the supply voltage VDD that supplies with on 2 inverter circuits of above-mentioned holding circuit 110 boosts.Booster circuit 95 begins to boost according to the end signal Vend during writing from timing controller (not shown).

Form this signal Vend according to vertical synchronizing signal Vsync, but also can use vertical synchronizing signal Vsync itself from external definition controller (not shown).As booster circuit 95, can suitably select, for example can use the circuit of charge-pump type.

Fig. 2 represents the circuit structure of booster circuit 95.In Fig. 2, the 160th, come the ring oscillator (RingOscillator) of starting oscillation action according to the end signal Vend during writing.The running clock of this ring oscillator 160 is applied on the end of capacitor C 1, C2 by phase inverter.Here, determine the progression of above-mentioned phase inverter, make the clock PCLK1 that applies on the clock PCLK2 that applies on the capacitor C 1 and the capacitor C 2 have phases opposite.

The supply voltage of ring oscillator 160 and phase inverter is Vdd.Therefore, the amplitude of clock PCLK1 and clock PCLK2 also is Vdd.The tie point N1 coupling of the other end of capacitor C 1 and TFT161 and TFT162.

In addition, the tie point N2 of the other end of capacitor C 2 and TFT163 and TFT164 coupling.Here, TFT161 and TFT163 are the N channel-types, and supply voltage Vdd (for example, 3V) is supplied to their source electrode.TFT162 and TFT164 are the P channel-types, and their source electrode is interconnected.Obtain the voltage VPP that boosts from this public source electrode.

In original state, be provided for the voltage of tie point N1 is set at the initial setting TFT165 of supply voltage Vdd.Equally, in original state, be provided for the voltage of tie point N2 is set at the initial setting TFT166 of supply voltage Vdd.TFT165 and TFT166 are the N channel-types, supply voltage Vdd are supplied with their grid and source electrode.

The following describes the work of the booster circuit of said structure.According to end signal Vend, after the ring oscillator 160 starting oscillations actions, clock PCLK2 is applied on the capacitor C 1, the clock PCLK1 of opposite phase is applied on the capacitor C 2.When clock PCLK2 is high level, the voltage of tie point N1 is risen by capacitive coupling.If the capacitance of capacitor C 1 is fully gone up the capacitance of subsidiary stray capacitance greater than tie point N1, then the voltage of tie point N1 is 2Vdd.For example, if Vdd is 3V, then the voltage of tie point N1 is 6V.At this moment, because TFT162 and 163 conductings, so the voltage 6V that boosts is exported as voltage VPP by TFT162.

Then, clock PCLK2 drops to low level, when clock PCLK1 rises to high level, by capacitive coupling the voltage of tie point N2 is risen.If the capacitance of capacitor C 2 is fully gone up the capacitance of subsidiary stray capacitance greater than tie point N2, then the voltage of tie point N2 is 2Vdd.For example, if Vdd is 3V, then the voltage of tie point N2 is 6V.Thus, TFT162 and 163 ends, and TFT161 and 165 conductings.So the voltage of tie point N1 turns back to Vdd (3V) once more.Simultaneously, the 6V voltage that boosts by TFT164 is exported as voltage VPP.By repeating above-mentioned action, Vdd boosts with supply voltage, exports as voltage VPP.

Fig. 3 is the circuit structure diagram of the commutation circuit of picture signal.When switch SW 1 is connected with terminals P 2 sides, be transformed to analog picture signal from the data image signal of the n position of input terminal Din input by DA transducer 130 after, output to data line 62.

On the other hand, when switch SW 1 switches to terminals P 1, for example most significant digit of the data image signal of n position is outputed to data line 62.The switching of switch SW 1 is carried out according to the mode switching signal MD of the digital display mode switching of control simulation display mode and the low correspondence of consumed power.

Below, the driving method of the display device of said structure is described referring to figs. 1 through Fig. 4.

Fig. 4 is that liquid crystal indicator is selected the timing diagram under the digital display mode situation.

(1) situation of simulation display mode

According to mode select signal MD, when selecting the simulation display mode, data signal line 62 is set to the state of output analog picture signal, and circuit selection signal line 88 becomes ' L ', TFT41,44 conductings of

circuit selection circuit

40,43.

According to come conducting sampling transistor SP based on the sampled signal of horizontal enabling signal STH, the analog picture signal of data signal line 62 is supplied with drain signal line 61.

In addition, according to vertical enabling signal STV, sweep signal is supplied with signal line 51.According to sweep signal, during the TFT71 conducting, analog picture signal Sig is delivered to show electrode 80 from drain signal line 61, remain on simultaneously in the auxiliary capacitor 85.The image signal voltage that applies on the show electrode 80 is applied on the liquid crystal 21,, can obtains liquid crystal display by liquid crystal is orientated according to this voltage.

In this simulation display mode, be fit to show full-color image.Wherein, in order to drive in addition LSI91, each

driver

50,60 of circuit substrate 90, thereby constantly consume electric power.

(2) digital display mode

According to mode switching signal MD, when selecting digital display mode, be set to the state of output digital image signal on the data signal line 62, and the current potential of circuit selection signal line 88 becomes ' H ', holding circuit 110 becomes the state that can work.In addition, circuit selects the TFT41,44 of

circuit

40,43 to end TFT42,45 conductings.

With LSI91 enabling signal STV, STH are input to gate drivers 50 and drain driver 60 from the screen board driving of tyre circuit substrate 90.Produce sampled signal successively according to enabling signal, according to each sampled signal come successively conducting sampling transistor SP1, SP2 ..., SPn, Sig samples to data image signal, supplies with each drain signal line 61.

Here, illustrate that the 1st goes, promptly applies the signal line 51 of sweep signal G1.At first, by sweep signal G1 make on the signal line 51 each display pixel that connects each pixel P11, P12 ..., P1n each TFT conducting 1 horizontal scan period.

If pay close attention to the display pixel P11 of the 1st row the 1st row, then the data image signal S11 that samples be input to drain signal line 61 by sampled signal SP1.Then, after TFT72 became conducting state by sweep signal G1, this drain signal D1 was written to the holding circuit 110 of display pixel P11.

Write fashionablely at this, the supply voltage VDD that supplies with on two inverter circuits with holding circuit l10 is set at holding circuit 110 and keeps the required minimum voltage (for example 3V) of data.Therefore, because the conducting resistance of the N channel-type TFT of phase inverter INV2 shown in Figure 1 raises, the threshold value of phase inverter INV1 descends simultaneously, so the output node at phase inverter INV1 is ' during H ' level, writing drain signal D1's (=data image signal S11) ' under the situation of H ' level, the nargin that writes improves.

That is, owing to can reduce drain signal D1's (=data image signal S11) ' voltage of H ' level, so can reduce the supply voltage of drain driver 60 driving circuits such as grade.In addition, can also reduce to constitute the size of the TFT72 of pixel selection circuit 70.

The signal that keeps in this holding circuit 110 is imported into signal selecting circuit 120, and this signal selecting circuit 120 is selected signal A or signal B, and the signal of selecting is applied on the show electrode 80, and this voltage is applied on the liquid crystal 21.Like this, by carrying out the scanning of signal line 51, finish writing of 1 picture (1 field interval) from signal line 51 to last row.

Then, carry out demonstration (demonstration of rest image) based on the data that keep in the holding circuit 110.Then,, make booster circuit 95 actions, the supply voltage VDD that supplies with on the holding circuit 110 is boosted according to the end signal Vend during writing.At this moment, supply voltage VDD preferably boosts to than the high voltage of voltage that adds TFT121,122 threshold voltage (Vt) gained on the ceiling voltage of signal A, B.

Thus, by TFT121,122 signal A, B are not supplied with show electrode 80 in decreased level ground, so can obtain the demonstration of good image quality.

When this numeral display mode, stop the voltage of gate drivers 50 and drain driver 60 and tyre screen board driving usefulness LSI91 is supplied with, their driving is stopped.110 frequent service voltage VDD, VSS drive to holding circuit, in addition, opposed electrode voltage are supplied with opposite electrode 32, and each signal A and B are supplied with selection circuit 120.

Promptly, supply with holding circuit 110 at the VDD that will be used to drive this holding circuit, VSS, opposed electrode voltage VCOM (signal A) is applied on the opposite electrode, liquid crystal display panel 100 is under the situation of normal white (NW), to be applied to the voltage of opposite electrode 32 same potential on the signal A, the alternating voltage (for example 60Hz) that only will be used to drive liquid crystal is applied to signal B.Thus, can keep 1 picture to be used as rest image shows.In addition, be in the state that voltage is not applied on other gate drivers 50, drain driver 60 and the tyre LSI91.

At this moment, data image signal in drain signal line 61 ' H (height) ' is input under the situation of holding circuit 110, in signal selecting circuit 120, be input to 1TFT121 owing to ' L ', so 1TFT121 ends, owing to ' H ' is input to another 2TFT122, so the 2TFT conducting.

So, select signal B, the voltage of signal B is applied on the liquid crystal.That is, owing to apply the alternating voltage of signal B, liquid crystal is upright because of electric field, so can be observed black display as demonstration when the display panel of NW.

Data image signal in drain signal line 61 ' L ' is input under the situation of holding circuit 110, owing in signal selecting circuit 120, ' H ' is input to 1TFT121, so the 1TFT121 conducting, because ' L ' is input to 2TFT122, so 2TFT122 ends.

So, select signal A, the voltage of signal A is applied on the liquid crystal.That is, owing to apply the voltage identical with opposite electrode 32, liquid crystal is not upright so do not produce electric field, when the display panel of NW as showing that can be observed white shows.

Like this, can be used as the rest image demonstration by keeping writing 1 picture, but in this case, owing to stop the driving of each

driver

50,60 and LSI91, so can make this part consumed power low.

As described above, according to embodiments of the invention, can tackle dynamic image demonstration (situation of simulation display mode) and digital tone demonstration (situation of digital display mode) these two kinds of demonstrations of full color with 1 liquid crystal display panel 100.In addition, can prevent that holding circuit 110 from writing fashionable misoperation, and can make consumed power low and carry out the fine Butut of pixel.

The display device that can select to simulate display mode and digital display mode has been described in the above-described embodiments, but the present invention also can be widely used in comprising the holding circuit 110 that writes, keep data image signal, carry out the display device that image shows according to this holding signal.

Display device of the present invention also is applied to reflection-type liquid-crystal display device especially in liquid crystal indicator.Therefore, the device architecture of this reflection-type liquid-crystal display device is described with reference to Fig. 5.

As shown in Figure 5, on an insulativity substrate 10, on the semiconductor layer 11 of the island that polysilicon constitutes, form gate insulating film 12, on the gate insulating film above the semiconductor layer 11 12, form gate electrode 13.

On the semiconductor layer 11 of the lower floor of 13 liang of side positions of gate electrode, form source electrode 11s and drain electrode 11d.On gate electrode 13 and gate insulating film 12, pile up interlayer dielectric 14, with this corresponding position of drain electrode 11d and with the corresponding position of source electrode 11s on form contact hole 15, by this contact hole 15, the 11d that will drain is connected to drain electrode 16, and source electrode 11s also is connected to show electrode 19 by the contact hole 18 that is provided with in the planarization insulating film 17 that is provided with on the interlayer dielectric 14.

Each pixel electrode 19 that forms on the planarization insulating film 17 is made of aluminium reflecting materials such as (Al).On each show electrode 19 and planarization insulating film 17, form the alignment films 20 that polyimide that liquid crystal 21 is orientated etc. is constituted.

On another insulativity substrate 30, formation presents red (R), green (G), blue (B) color filter 31, the opposite electrode 32 that ITO transparent and electrically conductive films such as (Indium Tin Oxide) constitutes and alignment films 33 that liquid crystal 21 is orientated of all kinds successively.Do not carrying out not needing color filter 31 under the colored situation about showing.

The periphery of a pair of

insulativity substrate

10,30 that forms is like this bondd with the cohesiveness encapsulant, and filling liquid crystal 21 in the space of formation is thus finished reflection-type liquid-crystal display device.

Shown in dotted arrow among the figure,, reflect from opposite electrode substrate 30 incident successively from the outer light of observer's 1 side incident by show electrode 19, inject to observer's 1 side, observer 1 can observe demonstration.

Like this because reflection-type liquid-crystal display device is the outer light of the reflection mode of observing demonstration, the liquid crystal indicator that does not need infiltration type like that with observer's opposite side use so-called backlight, so this power backlight that do not need to light a fire.Therefore, as display device of the present invention, preferably do not need reflection-type liquid-crystal display device backlight, as to be fit to the saving consumed power.

In the above-described embodiments, be illustrated in the voltage condition that applies opposed electrode voltage and signal A and signal B during the full spot scan of 1 picture, but the present invention is not limited to this, even also can not apply these voltage during this period.

In the above-described embodiments, illustrated in digital display mode, import the situation of 1 digital data signal, but the present invention has been not limited to this, also can be applied to the situation of the digital data signal of multidigit.

Like this, can carry out the demonstration of masstone.At this moment, need with the input corresponding number holding circuit and the signal selecting circuit of figure place.

In the above-described embodiments, illustrated rest image is presented at situation on the part of liquid crystal display panel, but the application is not limited to this, also can show still frame on all display pixels, has the distinctive effect of the present invention.

In the above-described embodiments, the situation of reflection-type liquid-crystal display device has been described, but, also can be used for transmission type liquid crystal display device by in 1 pixel, disposing transparency electrode in the zone except TFT, holding circuit, signal selecting circuit and signal routing.Be used under the situation of transmission type liquid crystal display device, after showing 1 picture,, can realizing reducing the consumed power of this part by stopping voltage supply to gate drivers 50 and drain driver 60 and the driving of screen board in addition LSI91.

The following describes the display device of the present invention the 2nd embodiment.Fig. 6 represents the circuit structure diagram of display device applications of the present invention under EL (electroluminescence) display device situation.Near the configuration pixel selection TFT72 cross part of signal line 51 and drain signal line 61 is connected to holding circuit 110 with the source electrode of TFT72.Holding circuit 110 is made of 2 inverter circuit INV1, INV2 of positive feedback.

And the output of holding circuit 110 is applied on the grid of EL drive TFT 125 of N channel-type.The source electrode of EL drive TFT is connected to voltage source V A, simultaneously drain electrode is connected to the anode of organic EL 22.The negative electrode 33 of organic EL 22 is biased to utility voltage VCOM.

Here, same with the foregoing description, will be written to holding circuit 110 from the Digital Image Data of drain electrode signal wire 61.Here, during writing, data are set at the required minimum voltage of holding circuit 110 maintenance data (for example, 3V) with constituting the supply voltage VDD that supplies with on 2 inverter circuits of holding circuit 110.

When consideration is exported the situation of ' H ' from holding circuit 110, on the grid of EL drive TFT 125, form lower voltage (for example 3V).Here, by adjusting the threshold value of EL drive TFT 125, organic EL 22 is cut-off state or high impedance status, forms the element that extinguishes.

Then, after finishing during data write, the data that keep in based on holding circuit 110 show that VDD is elevated to high voltage with supply voltage during (rest image demonstration).So the grid voltage of EL drive TFT 125 also uprises.Therefore, the bias voltage that applies more than the VF on the anode by organic EL 22 becomes conducting state, thereby lights.

Therefore, EL display device according to said structure, by during writing in data supply voltage VDD being reduced setting, same with the foregoing description, can realize that consumed power is low, and by supply voltage VDD is raise, thereby organic EL is lighted, obtained good luminous demonstration.

According to display device of the present invention, comprising the display device that is used on each display pixel, keeping the holding circuit of data image signal, because the supply voltage supplied with on holding circuit is fashionablely set lowly writing, set highly during demonstration after writing, so can prevent from the data mistake of this holding circuit is write, and realize that consumed power is low.

According to display device of the present invention, owing to can reduce the pixel selection element, so can carry out the fine Butut of pixel.

Claims

1. display device, comprise along a plurality of signal lines of the configuration of direction on the substrate and a plurality of drain signal line of disposing along the direction of intersecting with described signal line, by selecting from the sweep signal of described signal line and being rectangular configuration from the display pixel that described drain signal line is supplied with picture signal, it is characterized in that, comprising:

Holding circuit writes data image signal from described drain signal line according to the signal from the input of described signal line, and keeps this data image signal; And

Booster circuit after the writing of described data image signal, boosts the supply voltage of supplying with described holding circuit,

Output according to described holding circuit shows.

2. display device as claimed in claim 1 is characterized in that,

Described holding circuit is made of the two-stage inverter circuit of positive feedback.

3. display device as claimed in claim 2 is characterized in that,

Described inverter circuit is a CMOS type inverter circuit.

4. display device as claimed in claim 1 is characterized in that,

Comprise the signal selecting circuit of selecting to supply with the signal of show electrode according to the output of described holding circuit,

This signal selecting circuit is made of a plurality of thin film transistor (TFT)s that will be applied to from the signal of described holding circuit on the grid.

5. display device as claimed in claim 4 is characterized in that,

The supply voltage that is boosted by described booster circuit is added in the voltage of signals height of supplying with described show electrode than the threshold voltage with described thin film transistor (TFT).

6. the driving method of a display device, described display device comprises:

Along a plurality of signal lines of the configuration of direction on the substrate,

The a plurality of drain signal line that dispose along the direction of intersecting with described signal line,

By select from the sweep signal of described signal line and from described drain signal line supply with picture signal the display pixel that is rectangular configuration,

In described display pixel according to the signal from the input of described signal line write from the data image signal of described drain signal line and keep this data image signal holding circuit and

The booster circuit that the supply voltage of supplying with described holding circuit is boosted,

Wherein, described display device shows according to the output of described holding circuit,

The driving method of described display device is characterised in that:

According to signal from described signal line input, after will writing described holding circuit from the data image signal of described drain signal line, the supply voltage that to be supplied with described holding circuit by described booster circuit boosts, and carries out the image corresponding with described data image signal and shows.

7. the driving method of display device as claimed in claim 6 is characterized in that,

Described holding circuit is made of 2 grades of inverter circuits of positive feedback.

8. the driving method of display device as claimed in claim 7 is characterized in that,

Described inverter circuit is a CMOS type inverter circuit.

9. the driving method of display device as claimed in claim 6 is characterized in that,

10. the driving method of display device as claimed in claim 9 is characterized in that,