CN102376239B - Pixel circuit of display device - Google Patents
Pixel circuit of display device Download PDFInfo
- Publication number
- CN102376239B CN102376239B CN 201010264049 CN201010264049A CN102376239B CN 102376239 B CN102376239 B CN 102376239B CN 201010264049 CN201010264049 CN 201010264049 CN 201010264049 A CN201010264049 A CN 201010264049A CN 102376239 B CN102376239 B CN 102376239B
- Authority
- CN
- China
- Prior art keywords
- voltage
- switch
- coupled
- output terminal
- write
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Abstract
The invention provides a pixel circuit of a display device, which enables the value of voltage transmitted to a display element to be approximate to the value of received data voltage so that the pixel circuit can trustily transmit the data voltage to the display element. The pixel circuit of the display device comprises a first write-in switch, a first write-in storing unit, a first voltage following module and the display element. The first voltage following module is used for detecting a first data voltage which is stored in the first write-in storing unit and generating a corresponding first output end voltage on the display element according to the detection result; and the output end of the first voltage following module is controlled by a switch voltage.
Description
Technical field
The present invention relates to a kind of image element circuit, particularly relate to a kind of image element circuit of display device.
Background technology
Flat-panel screens, as: liquid crystal display (Liquid Crystal Display, LCD) etc., it has that high image quality, volume are little, lightweight, low driving voltage, with the advantage such as low consumpting power, therefore be widely used in and shoot with video-corder projector, personal digital assistant (Personal Digital Assistant, PDA), in the consumer communication such as mobile phone, mobile computer, desktop PC display screen and slim Digital Television or electronic product, and replace gradually cathode-ray tube (CRT) (Cathode Ray Tube, CRT) and become the mainstream technology of display.
In general flat display apparatus framework, two-d display panel is comprised of pel array, and pel array comprises a plurality of image element circuits.Image element circuit in the past mainly is comprised of passive devices such as electric capacity, switches, therefore there is charge redistribution (chargesharing) effect when transmitting the image data signal unavoidablely, make in image element circuit the data signals that display element receives that a little drop is arranged, cause its shown pixel to produce the situation beyond expection, such as: on the gray scale that pixel shows and data signals, desired pixel grey scale has a little deviation, distortion and inaccurate etc.The charge redistribution effect often betides on DLC (digital logic circuit), because element internal has coupling capacitance, thereby can reduce the magnitude of voltage of wanting output voltage or signal in circuit.
Summary of the invention
The invention provides a kind of image element circuit of display device, make the pixel voltage value of image element circuit close to received image data voltage, allow image element circuit when transmission image data voltage verily transfer overvoltage to display element, to reduce the impact of coupling capacitance and electric current weight partition effect in element.
The present invention proposes a kind of image element circuit of display device, comprises the first write switch, the first write storage unit, the first voltage follow module and a display element.The first end of the first write switch is coupled to a data line, and the first write switch is controlled by one first switching voltage.The first write storage unit is coupled to the second end of the first write switch, and wherein the first write storage unit stores the first data voltage via the first write switch.The input end of the first voltage follow module is coupled to the first write storage unit, be stored in the first data voltage of the first write storage unit in order to detection, and produce the first corresponding output end voltage according to testing result in the output terminal of the first voltage follow module, wherein the output terminal of the first voltage follow module is controlled by a second switch voltage.Display element couples the output terminal of the first voltage follow module, in order to during a picture, via the first voltage follow module, to receive the first output end voltage.
In one embodiment of this invention, the first above-mentioned voltage follow module comprises the first voltage follower and the first display switch.The input end of the first voltage follower becomes the input end of the first voltage follow module.The first end of the first display switch is coupled to the output terminal of the first voltage follower, and its second end becomes the output terminal of the first voltage follow module, and the first display switch is controlled by second switch voltage.
In one embodiment of this invention, the first above-mentioned voltage follower comprises an operational amplifier, its first input end becomes the input end of the first voltage follower, and the output terminal of operational amplifier is coupled to the second input end of operational amplifier and becomes the output terminal of the first voltage follower.
In one embodiment of this invention, the first above-mentioned voltage follower comprises the one source pole follower, and this source follower comprises the first transistor and transistor seconds.The control end of the first transistor becomes the input end of source follower, and the first end of the first transistor receives a system voltage, and its second end becomes the output terminal of source follower.The control end of transistor seconds receives one and controls voltage, and the first end of transistor seconds receives a common voltage, and the second end of transistor seconds is coupled to the second end of the first transistor.
In one embodiment of this invention, the first above-mentioned voltage follow module comprises the first voltage follower and the first power control switch.The input end of the first voltage follower becomes the input end of the first voltage follow module, and the output terminal of the first voltage follower becomes the output terminal of the first voltage follow module.The first end of the first power control switch is coupled to the power input of the first voltage follower, and the second termination of the first power control switch is received system voltage, and the first power control switch is controlled by second switch voltage.
In one embodiment of this invention, also comprise a demonstration storage unit, it is coupled to the output terminal of voltage follow module.Wherein, show that storage unit comprises one second electric capacity, its first end is coupled to the output terminal of voltage follow module, and the second termination of the second electric capacity is received one second reference voltage.
In one embodiment of this invention, also comprise one first actuating switch, its first end is coupled to the first write storage unit, and the second end of the first actuating switch is coupled to display element, and the first actuating switch is controlled by the first conducting signal.
In one embodiment of this invention, also comprise that the second write switch, the second write storage unit and second voltage follow module.The first end of the second write switch is coupled to data line, and the second write switch is controlled by the 3rd switching voltage.The second write storage unit is coupled to the second end of the second write switch, and wherein the second write storage unit stores one second data voltage via the second write switch.The input end that second voltage is followed module is coupled to the first end of the second write storage unit, the output terminal that second voltage is followed module is coupled to display element, be stored in the second data voltage of the second write storage unit in order to detection, and the output terminal of according to testing result, in second voltage, following module produces one second corresponding output end voltage.Wherein, the output terminal that second voltage is followed module is controlled by the 4th switching voltage.
In one embodiment of this invention, above-mentioned second voltage is followed module and is comprised second voltage follower and the second display switch.The input end of second voltage follower becomes the input end that second voltage is followed module.The first end of the second display switch is coupled to the output terminal of second voltage follower, and the second end of the second display switch becomes the output terminal that second voltage is followed module, and the second display switch is controlled by the 4th switching voltage.
Based on above-mentioned, the voltage follower that embodiments of the invention utilization is comprised of active member (as: operational amplifier, source follower etc.), make image element circuit allow in transmission the voltage of display element is rough equals image data voltage during data voltage, and can not be subject to the impact of coupling capacitance and electric current weight partition effect element in.
For above-mentioned feature and advantage of the present invention can be become apparent, special embodiment below, and be described with reference to the accompanying drawings as follows.
The accompanying drawing explanation
Fig. 1 illustrates a kind of schematic diagram of image element circuit of display device according to the first embodiment of image element circuit.
Fig. 2 illustrates a kind of driving sequential chart of image element circuit of display device according to the first embodiment of image element circuit.
Fig. 3 illustrates a kind of schematic diagram of image element circuit of display device according to second embodiment of the invention.
Fig. 4 illustrates a kind of driving sequential chart of image element circuit of display device according to second embodiment of the invention.
Fig. 5 illustrates a kind of schematic diagram of image element circuit of display device according to third embodiment of the invention.
Fig. 6 illustrates a kind of driving sequential chart of image element circuit of display device according to third embodiment of the invention.
Fig. 7 illustrates a kind of circuit diagram of image element circuit of display device according to fourth embodiment of the invention.
Fig. 8 illustrates the circuit diagram of the first voltage follower according to fourth embodiment of the invention.
Fig. 9 illustrates the circuit diagram of the second display switch according to fourth embodiment of the invention.
Figure 10 illustrates a kind of circuit diagram of image element circuit of display device according to fifth embodiment of the invention.
Figure 11 illustrates a kind of circuit diagram of image element circuit of display device according to sixth embodiment of the invention.
Figure 12 illustrates the schematic diagram of the image element circuit of another kind of display device according to the 7th embodiment of image element circuit.
Figure 13 illustrates the driving sequential chart of the image element circuit of another kind of display device according to the 7th embodiment of image element circuit.
Figure 14 illustrates the schematic diagram of the image element circuit of another kind of display device according to eighth embodiment of the invention.
Figure 15 illustrates the schematic diagram of the image element circuit of another kind of display device according to ninth embodiment of the invention.
The reference numeral explanation
100,300,500,700,1000,1100,1200,1400,1500: image element circuit
110: the first write switch T2: wait to be shown during
120: the first write storage unit T3: during demonstration
130: the first display switch T4: wait for during writing
140: show storage unit T5: conduction period
During 150: display element T6: first write/the second demonstration
330: the first display switch T7: first latch during
360: the first voltage follow module T8: first shows that/the second writes period
370: the first voltage follower T9: second latch during
580: the first actuating switch Vcom: common voltage
1110,1120: the first power control switch Vlc: pixel voltage
1210: the second write switch Vn, Vn1, Vn2: end-point voltage
1220: the second write storage unit Vt: pressure drop voltage
1230: the second display switch Vto1: the first forward voltage
1430: the second display switch Vto2: the second forward voltage
1460: second voltage is followed module Vsw1: the first switching voltage
1470: second voltage follower Vsw2: the second reference voltage
1580: the second actuating switch Vref1: the first reference voltage
A, B, C: the first input end of operational amplifier, the second input end and output terminal
Cs1: the first electric capacity Vref2: the second reference voltage
Cs2: the second electric capacity Vss: system voltage
Cs3: the 3rd electric capacity MN, MN1, MN2:NOMS transistor
DataLine: data line MP:PMOS transistor
OP: operational amplifier M1～M4: computing transistor
Δ V, Δ V1, Δ V2: voltage difference
Embodiment
Meet the first embodiment of the image element circuit 100 of display device in this proposition, please refer to Fig. 1.Fig. 1 illustrates a kind of schematic diagram of image element circuit 100 of display device according to the first embodiment of image element circuit 100.The image element circuit 100 of display device comprises the first write switch 110, the first write storage unit 120, the first display switch 130 and display element 150.The first end of the first write switch 110 is coupled to a data line DataLine, and the first 110 of write switches are controlled by one first switching voltage Vsw1.The first end of the first write storage unit 120 is coupled to the second end of the first write switch 110, and its second end receives one first reference voltage Vref 1.Wherein, the first write storage unit 120 stores one first data voltage via the first write switch 110.The first end of the first display switch 130 is coupled to the first write storage unit 120, and wherein the first display switch 130 is controlled by a second switch voltage Vsw2.Display element 150 is coupled to the second end of the first display switch 130, and the other end of display element 150 receives common voltage Vcom.Display element 150 receives via second switch voltage Vsw2 the first data voltage stored by the first write storage unit 120 during a picture.
In the present embodiment, image element circuit 100 also comprises demonstration storage unit 140, and its first end is coupled to the second end of the first display switch 130, shows that the second end of storage unit 140 receives the second reference voltage Vref 2.In the present embodiment, display element 150 is for example liquid crystal capacitance 150.This liquid crystal capacitance 150 drives and the liquid crystal angle changed in liquid crystal capacitance 150 with the potential difference (PD) of common voltage Vcom by pixel voltage Vlc.
For describing the mode of operation of the present embodiment in detail, referring to Fig. 1 and Fig. 2.Fig. 2 illustrates a kind of driving sequential chart of image element circuit 100 of display device according to the first embodiment of image element circuit 100.Below voltage that the first write storage unit 120 is coupled on the first write switch 110 second ends be called end-point voltage Vn.Described according to the present embodiment, drive during each picture of sequential mainly be divided into four period: during writing T1, etc. to be shown during T2, show during T3 with wait for during writing T4.During writing T1 is the period that the first switching voltage Vsw1 is positioned at high level, and now second switch voltage Vsw2 is low level.Therefore, during writing T1 is also that the first write switch 110 is positioned at conducting state, and the first display switch 130 is positioned at the period of cut-off state.The first capacitor C s1 in the first write storage unit 120 receives the first data voltage V1 via the data line DataLine place of the first write switch 110, therefore the first capacitor C s1 is convenient to now store electric charge, and makes end-point voltage Vn equal the first data voltage V1.At this, pay special attention to, " end-point voltage Vn equals the first data voltage V1 " is the circuit analysis result be positioned under ideal state.And, in actual state, if while considering the circuits/devices of non-ideal characteristic, end-point voltage Vn can be less than the first data voltage V1.
Then enter etc. to be shown during T2.Etc. T2 during to be shown, being the first switching voltage Vsw1 and second switch voltage Vsw2 while all being positioned at low level, is also the period that the first write switch 110 and the first display switch 130 all are positioned at cut-off state.In now, the first capacitor C s1 in the first write storage unit 120 maintains the first data voltage V1 by the magnitude of voltage of end-point voltage Vn.
Afterwards, during demonstration, T3 is positioned at the period of high level for second switch voltage Vsw2, and the first switching voltage Vsw1 is low level.Accordingly, during demonstration T3 be also the first display switch 130 in conducting state, the first write switch 110 is the period in cut-off state.Ideally, the first stored data voltage V1 of the first capacitor C s1 should verily be transferred into display element 150.That is to say, after the first display switch 130 conductings, the pixel voltage Vlc of display element 150 should equal the first data voltage V1.Yet, because electric capacity heavily distributes (Charge sharing) effect, make in the stored charge-averaging of the first capacitor C s1 and be distributed in the first capacitor C s1, show in the second capacitor C s2 and liquid crystal capacitance 150 in storage unit 140, cause the pixel voltage Vlc of display element 150 to be not equal to the first data voltage V1.That is to say, produce a voltage difference delta V between pixel voltage Vlc and the first data voltage V1.For example, for the situation beyond expection reduce to occur the pixel that makes display circuit 100: the gray scale that pixel shows and the first data voltage V1 above desired pixel grey scale have a little deviation, distortion and inaccurate etc., and voltage difference delta V must be as best one can little.
Then enter and wait for during writing T4.Wait for during writing T4 with etc. to be shown during the state of T2 similar, the first switching voltage Vsw1 now and second switch voltage Vsw2 all are positioned at low level, and the first write switch 110 and the first display switch 130 all are positioned at cut-off state.Therefore, drive the required potential difference (PD) of liquid crystal capacitance 150 itself to be continued to provide by demonstration storage unit 140 and liquid crystal capacitance 150, and wait for that the during writing T1 of next picture arrives.In other embodiments, show that storage unit 140 can be omitted because of design requirement, and by the save data voltage of liquid crystal capacitance 150 own.
According to the present embodiment, image element circuit 100 will make to drive the pixel voltage Vlc of liquid crystal capacitance 150 and the first data voltage V1 to have voltage difference delta V, cause liquid crystal capacitance 150 can't correctly according to the first data voltage V1, change the angle of its liquid crystal.In order to reduce voltage difference delta V, can when design circuit, strengthen the capacitance of the first capacitor C s 1, and the first capacitor C s1 is designed to add much larger than the second capacitor C s2 the capacitance of liquid crystal capacitance 150, to reduce the fall of voltage difference delta V when the heavy partition effect of electric capacity occurs.But, due to the restriction of technique and volume-diminished now, the first capacitor C s1 and the second capacitor C s2 add that the capacitance of liquid crystal capacitance 150 is approaching all the more, so the amplitude of voltage difference delta V just increases to the stage that can't ignore gradually.
According to front described, the second embodiment according to the invention is proposed to reduce voltage difference delta V and to reduce the charge redistribution effect at this, please refer to Fig. 3.Fig. 3 illustrates a kind of schematic diagram of image element circuit 300 of display device according to second embodiment of the invention.Image element circuit 300 comprises the first write switch 110, the first write storage unit 120, the first voltage follow module 360 and display element 150.Wherein, the present embodiment is similar to the image element circuit 100 of above-mentioned the first embodiment, and therefore identical coupling mode and operation instructions do not repeat them here.In order to clearly state the present embodiment, input terminal voltage at this by the first voltage follow module 360 is called end-point voltage Vn1, and the output terminal of the first voltage follow module 360 is coupled to liquid crystal capacitance 150, therefore the first output end voltage of the first voltage follow module 360 equals pixel voltage Vlc.
In order to cause those skilled in the art can more understand the present invention, below for the difference of mode of operation in the image element circuit 300 of the image element circuit 100 of Fig. 1 and Fig. 3, be illustrated, therefore identical mode of operation does not repeat them here.Please refer to Fig. 4, Fig. 4 illustrates a kind of driving sequential chart of image element circuit 300 of display device according to second embodiment of the invention.During demonstration during each picture, in T3, now second switch voltage Vsw2 is positioned at high level, and the first switching voltage Vsw1 is low level.Accordingly, during showing, the first display switch 130 is also in conducting state during T3, and the first write switch 330 in the first voltage follow module 360 is in cut-off state.Known in previous narration, the input terminal voltage of the first voltage follow module 360 (that is end-point voltage Vn1) utilizes the first interior capacitor C s1 of the first writing memory element 120 to maintain magnitude of voltage, and now the magnitude of voltage of end-point voltage Vn1 equals the first data voltage V1.At this, pay special attention to, " end-point voltage Vn1 equals the first data voltage V1 " is the circuit analysis result be positioned under ideal state.In actual state, for example, if, while considering the circuits/devices of non-ideal characteristic (considering the pressure drop of the first write switch 110), end-point voltage Vn1 can be less than the first data voltage V1.
Under ideal state, the first voltage follower 370 in the first voltage follow module 360 can produce corresponding the first output end voltage (it is also the first data voltage V1) according to end-point voltage Vn1 (its magnitude of voltage is the first data voltage V1).Yet if, while considering the first voltage follower 370 of non-ideal characteristic, the magnitude of voltage of the magnitude of voltage of the first output end voltage and the first data voltage V1 may be different.Therefore, when the first display switch 330 during in conducting state, the output terminal of the first voltage follower 370 can be coupled to display element 150, makes rough the first output end voltage (that is first data voltage V1) that equals the first voltage follower 370 of pixel voltage Vlc.Show that memory element 140 also stores electric charge to maintain the first data voltage V1 during showing in T3.
Then, when waiting for during writing T4, the first write switch 110 and the first display switch 330 all are positioned at cut-off state.Show that storage unit 140 is convenient for the stored electric charge of the second capacitor C s2, by on the rough magnitude of voltage that maintains the first data voltage V1 of pixel voltage Vlc, drive the required potential difference (PD) of liquid crystal capacitance 150 to continue to provide, and wait for that the during writing T1 during next picture arrives.
In the present embodiment, utilize the first voltage follow module 360 to come verily the first data voltage V1 to be transferred to display element 150 from the input end of the first voltage follow module 360, reduce by this voltage difference delta V.Ideally, the output end voltage of the first voltage follower 370 can be set as equaling end-point voltage Vn1 (i.e. the first data voltage V1).Yet the first actual voltage follower 370 may have a little output error (or skew).Can carry out the aforementioned two-end-point of conducting by increasing a transmitting switch in other embodiment, to improve aforementioned output error (or skew), make pixel voltage Vlc more approach target voltage (i.e. the first data voltage V1), namely further reduce voltage difference delta V.Please refer to Fig. 5 and Fig. 6.Fig. 5 illustrates that according to third embodiment of the invention a kind of schematic diagram of image element circuit 500 of display device, Fig. 6 are that a kind of driving sequential chart of image element circuit 500 of display device is described according to third embodiment of the invention.Wherein, the present embodiment is similar to the image element circuit 300 of aforementioned the second embodiment, and therefore identical coupling mode and operation instructions do not repeat them here.
The difference of the second embodiment of the present embodiment and Fig. 3 is, image element circuit 500 also comprises one first actuating switch 580, its first end is coupled to the first write storage unit 120, the second end of the first actuating switch 580 is coupled to display element 150, the first actuating switchs 580 and is controlled by the first forward voltage Vto1.In the present embodiment, the output terminal of the first voltage follow module 360 and its input end have an offset voltage Vt.For example, during showing during T3, the first output end voltage of the first voltage follow module 360 (being pixel voltage Vlc), in equaling ideally first input end voltage Vn1 (i.e. the first data voltage V1), deducts but actual pixel voltage Vlc equals the first data voltage V1 the offset voltage Vt that the first voltage follow module 360 includes.If the voltage difference delta V of the first data voltage V1 and pixel voltage Vlc when T3 (during showing Δ V=Vt) is excessive to ignoring its impact, the present embodiment is convenient more to be dwindled voltage difference delta V with the first actuating switch 580, below detailed description.
According to the above, the present embodiment increases conduction period T5 in the wait during writing T4 that drives sequential, and now the first forward voltage Vto1 is positioned at noble potential.By this, the first actuating switch 580 is just in conducting state, and the first write switch 110 and the first display switch 330 all are positioned at cut-off state.In now, the two ends of the first actuating switch 580 are connected and cause the charge redistribution effect, make pixel voltage Vlc more approach the first data voltage V1, and allow voltage difference delta V more dwindle.
Below, for being described in more detail embodiments of the invention, the circuit framework in this describes the first voltage follow module 360 in detail, please refer to Fig. 7.Fig. 7 illustrates a kind of circuit diagram of image element circuit 700 of display device according to fourth embodiment of the invention.The present embodiment is similar to the image element circuit 500 of aforementioned the 3rd embodiment, and therefore identical coupling mode and operation instructions do not repeat them here.
Difference is, the first voltage follower 370 comprises operational amplifier OP, its first input end A (for example non-inverting input) becomes the input end of voltage follower 370, and the output terminal C of operational amplifier OP is coupled to the second input end B (for example inverting input) of operational amplifier OP and becomes the output terminal of the first voltage follower 370.By this, operational amplifier OP detects the magnitude of voltage (that is end-point voltage Vn1) on first input end A, and produces corresponding magnitude of voltage in output terminal C, to realize the purpose of the present embodiment.Application the present embodiment person can realize that the circuit design of this operational amplifier OP is to realize aforesaid identical function according to its demand.
In the present embodiment, the detailed circuit diagram of operational amplifier OP is illustrated in Fig. 8.Fig. 8 illustrates the circuit diagram of the first voltage follower 370 according to fourth embodiment of the invention.Operational amplifier OP comprises the first computing transistor M1, the second computing transistor M2, the 3rd computing transistor M3 and the 4th computing transistor M4.Wherein, the first computing transistor M1 and the second computing transistor M2 are P-channel metal-oxide-semiconductor (P-channel metal oxide semiconductor in the present embodiment, PMOS) transistor, the 3rd computing transistor M3 and the 4th computing transistor M4 are N NMOS N-channel MOS N (N-channel metal oxide semiconductor, NMOS) transistor.
The first end of the first computing transistor M1 (for example source terminal) receiving system voltage Vss, and its second end (for example drain electrode end) is coupled to the control end (for example gate terminal) of the first computing transistor M1.The first end of the second computing transistor M2 (for example source terminal) receiving system voltage Vss, and its control end (for example gate terminal) is coupled to the control end of the first computing transistor M1.The first end of the 3rd computing transistor M3 (for example drain electrode end) is coupled to the transistorized control end of the first computing (for example gate terminal), and its second end (for example source terminal) receives a common voltage Vcom.The control end of the 3rd computing transistor M3 (for example gate terminal) becomes the input end of operational amplifier OP.The first end of the 4th computing transistor M4 (for example drain electrode end) is coupled to the control end (for example gate terminal) of the 4th computing transistor M4 and the second end (for example drain electrode end) of the second computing transistor M2, to become the output terminal of operational amplifier OP, the second end of the 4th computing transistor M4 (for example source terminal) receives common voltage Vcom.Other unaccounted modes of operation of this operational amplifier OP can be understood easily and implement for those skilled in the art, at this, do not add to repeat.Visual its demand of application the present embodiment person is replaced aforementioned operational amplifier OP with the operational amplification circuit of identical function, to realize by this purpose of the present embodiment.
In addition, application the present embodiment person also can design the first write switch 110, the first display switch 330 and the first actuating switch 580 according to its demand, to realize above-mentioned functions.Take the first display switch 330 at this is example, please refer to Fig. 9, and Fig. 9 illustrates the circuit diagram of the first display switch 330 according to fourth embodiment of the invention.The first display switch 330 for example is comprised of a nmos pass transistor MN and a PMOS transistor MP in the present embodiment, and it is controlled by the first forward voltage Vsw2.First display switch 330 other unaccounted modes of operation can be understood easily and implement for those skilled in the art, and can also realize the first display switch 330 by single transistor in other embodiment, at this, do not add to repeat.
In other embodiment, the first voltage follower 370 can also utilize source follower (sourcefollower) to realize, please refer to Figure 10.Figure 10 illustrates the circuit diagram of the image element circuit of another kind of display device according to fifth embodiment of the invention.The present embodiment is similar to aforementioned the 3rd embodiment, and therefore identical coupling mode and operation instructions do not repeat them here.In image element circuit 1000, the source follower of the first voltage follower 370 comprises the first transistor MN1 and transistor seconds MN2.
In the present embodiment, the first transistor MN1 and transistor seconds MN2 are for example the NOMS transistors.The control end of the first transistor MN1 becomes the input end of source follower 370, and the first end of the first transistor MN1 receives a system voltage Vss, and the second end of the first transistor MN1 becomes the output terminal of source follower 370.The control end of transistor seconds MN2 receives one and controls voltage VB, and its first end receives common voltage Vcom, and the second end of transistor seconds MN2 is coupled to the second end of the first transistor MN1.By this, output terminal and its input end of the source follower in the first voltage follow module 360 have offset voltage Vth, therefore it drives sequential just as Fig. 6, can utilize the first conducting signal Vto1 to control the first actuating switch 580, to dwindle the voltage difference delta V of the first data voltage V1 and pixel voltage Vlc, and realize the purpose of the present embodiment.
In addition, the output terminal of the first voltage follow module 360 is controlled by the implementation method of second switch voltage Vsw2 except aforementioned implementation, also can utilize second switch voltage Vsw2 to come the power supply of control algorithm amplifier OP to supply to realize above-mentioned purpose, please refer to Figure 11.Figure 11 illustrates a kind of circuit diagram of image element circuit of display device according to sixth embodiment of the invention.
The first voltage follow module 360 of image element circuit 1100 comprises the first voltage follower 370, the first power control switch 1110 and the first power control switch 1120.The input end of the first voltage follower 370 becomes the input end of the first voltage follow module 360, and the output terminal of the first voltage follower 370 becomes the output terminal of the first voltage follow module 360.The first end of the first power control switch 1110 is coupled to the power input of the first voltage follower 370, and the second termination of the first power control switch 1110 is received system voltage Vss.And the first end of the first power control switch 1120 is coupled to the ground connection input end of the first voltage follower 370, the second end of the first power control switch 1110 receives common voltage Vcom.
Wherein, the first power control switch 1110 and the first power control switch 1120 all are controlled by second switch voltage Vsw2.Because the first voltage follower 370 is comprised of active member (as: operational amplifier OP, source follower etc.) in the present embodiment, therefore can rely on the power supply of controlling active member and the first output end voltage of controlling by this first voltage follower 370.Therefore, as second switch voltage Vsw2, during in low level, the first power control switch 1110 and the first power control switch 1120 become cut-off state, and the first voltage follower 370 just can't produce the first output end voltage.Relatively, as second switch voltage Vsw2 during in high level, the first power control switch 1110 and the first power control switch 1120 become conducting state by this, the first voltage follower 370 could come into operation by power supply, realizes the function of the present embodiment to control further the pixel voltage Vlc on display element 150.
The first voltage follower 370 comprises operational amplifier OP in the present embodiment, its first input end A (being for example non-inverting input) becomes the input end of the first voltage follower 370, and the output terminal C of operational amplifier OP is coupled to the second input end B (being for example reverse input end) of operational amplifier OP and becomes the output terminal of the first voltage follower 370.Other detailed process of the present embodiment are included in the various embodiments described above, therefore do not repeat them here.
With another viewpoint, at this, another kind of the 7th embodiment that meets the image element circuit 1200 of display device is proposed, please refer to Figure 12 and Figure 13.Figure 12 illustrates the schematic diagram of the image element circuit 1200 of another kind of display device according to the 7th embodiment of image element circuit 1200.Figure 13 illustrates the driving sequential chart of the image element circuit 1200 of another kind of display device according to the 7th embodiment of image element circuit 1200.Image element circuit 1200, except having the first write switch 110, the first write storage unit 120, the first display switch 130 and display element 150, also comprises the second write switch 1210, the second write storage unit 1220 and the second display switch 1230.
The first end of the second write switch 1210 is coupled to data line DataLine, and the second write switch 1210 is controlled by the 3rd switching voltage, and in the present embodiment, the 3rd switching voltage equals second switch voltage Vsw2.The second write storage unit 1220 is coupled to the second end of the second write switch 1210, and wherein the second write storage unit 122 stores the second data voltage via the second write switch 1210.The first end of the second display switch 1230 is coupled to the second write storage unit 1220, and wherein the first display switch 1230 is controlled by the 4th switching voltage, and in the present embodiment, the 4th switching voltage equals the first switching voltage Vsw1.In addition, image element circuit 1200 also comprises demonstration storage unit 140, comprises one second capacitor C s2 in it, and other thin sections explanations of the present embodiment have been included in the various embodiments described above, therefore do not repeat them here.
Mode of operation and flow process at this pixels illustrated circuit 1200.For clearly stating the present embodiment, the voltage at this by the first write storage unit 120 first ends is called first end point voltage Vn1, and the voltage of the second write storage unit 1220 first ends is called to the second end-point voltage Vn2.In the described driving sequential of the present embodiment, every two pictures are a cycle period, so each cycle period has four periods: first write/second show during T6, first latch during T7, first show/the second write period T8 and second latch during T9.
In first writing/second show during during T6, the first switching voltage Vsw1 is positioned at high level, and second switch voltage Vsw2 is positioned at low level.Therefore, the first write switch 110 and the second display switch 1230 are positioned at conducting state, and the first display switch 130 and the first write switch 1210 are positioned at cut-off state.The first capacitor C s1 in the first write storage unit 120 receives the first data voltage V1 via the data line DataLine place of the first write switch 110, makes first end point voltage Vn1 equal the first data voltage V1.
The 3rd capacitor C s3 in the second write storage unit 1220 will write stored the second data voltage V2 (i.e. the second end-point voltage Vn2) of T8 in period in previous the first demonstration/the second and be sent to liquid crystal capacitance 150.Ideally, the first stored data voltage V1 of the first capacitor C s1 should verily be transferred into display element 150.Yet, due to the charge redistribution effect, make and in fact between the pixel voltage Vlc of display element 150 (or second end-point voltage Vn2) and the second data voltage V2, produce a voltage difference delta V2.Now liquid crystal capacitance 150 shows the pixel of first picture by pixel voltage Vlc.
Then enter first latch during T7, now the first switching voltage Vsw1 and second switch voltage Vsw2 all are positioned at low level.Therefore, the first write switch 110, the second write switch 1210, the first display switch 130 and the second display switch 1230 all are positioned at cut-off state.In now, the first capacitor C s1 in the first write storage unit 120 maintains the first data voltage V1 by the magnitude of voltage of first end point voltage Vn1.Show that storage unit 140 and the coupling capacitance in liquid crystal capacitance 150 continue to maintain the potential difference (PD) that drives liquid crystal capacitance 150 required, allow liquid crystal capacitance 150 continue to show the pixel of first picture.In other embodiments, show that storage unit 140 can be omitted because of design requirement, and by the save data voltage of liquid crystal capacitance 150 own.
Afterwards, enter the first demonstration/second and write T8 in period.Now second switch voltage Vsw2 is positioned at high level, and the first switching voltage Vsw1 is low level.Accordingly, in the first demonstration/second, write period during T8, the first display switch 130 and the second write switch 1210 are in conducting state, and the first write switch 110 and the second display switch 1230 are in cut-off state.Now, due to the heavy partition effect of electric capacity, make the pixel voltage Vlc (being first end point voltage Vn1) of display element 150 and the first data voltage V1 produce a voltage difference delta V1.Now liquid crystal capacitance 150 shows the pixel of second picture by pixel voltage Vlc.
Then enter second latch during T9.Second latch during T9 and first latch during the state of T7 similar, the first write switch 110, the second write switch 1210, the first display switch 130 and the second display switch 1230 all are positioned at cut-off state.Therefore, the 3rd capacitor C s3 in the second write storage unit 1220 maintains the second data voltage V2 by the magnitude of voltage of end-point voltage Vn2.Coupling capacitances in demonstration storage unit 140 and liquid crystal capacitance 150 continue to maintain the required potential difference (PD) of driving liquid crystal capacitance 150, make liquid crystal capacitance 150 continue to show the pixel of second picture, and during waiting for next first write/the second demonstration, T6 arrives.
According to front described, in order to dwindle as best one can voltage difference delta V1 and voltage difference delta V2, and reduce the impact that the charge redistribution effect is brought, at this, the 8th embodiment according to the invention is proposed, so that image element circuit in transmission during data voltage verily transfer overvoltage to liquid crystal capacitance 150, please refer to Figure 14 and Figure 15.Figure 14 illustrates the schematic diagram of the image element circuit of another kind of display device according to eighth embodiment of the invention.Figure 15 illustrates the schematic diagram of the image element circuit of another kind of display device according to ninth embodiment of the invention.
The 8th embodiment, the 9th embodiment and the 7th embodiment difference are, the 8th embodiment and the 9th embodiment utilize the first voltage follow module 360 to follow module 1430 with second voltage and verily transmit data voltage to liquid crystal capacitance 150, make the pixel voltage value of image element circuit close to received data voltage.The input end of the first voltage follow module 360 is coupled to the first write storage unit 120, and its output terminal is coupled to display element 150.The input end that second voltage is followed module 1460 is coupled to the second write storage unit 1220, and its output terminal also is coupled to display element 150.
In addition, follow interior the had output error of module 1430 or offset voltage for solving in fact the first voltage follow module 360 with second voltage, more add the first actuating switch 580 and the second actuating switch 1580 in the 9th embodiment, to improve aforementioned output error (or offset voltage), make pixel voltage Vlc more approach target voltage (i.e. the first data voltage V1 or the second data voltage V2), namely further reduce voltage difference delta V1 and voltage difference delta V2.The second end that wherein first end of the second actuating switch 1580 is coupled to the second write storage unit 1220, the second actuating switchs 1580 is coupled to display element 150, the second actuating switchs 1580 and is controlled by the second conducting signal.Wherein, other same or similar thin section flow processs of the 8th embodiment and the 9th embodiment are included in the various embodiments described above, therefore do not repeat them here.
In sum, the voltage follow module that embodiments of the invention utilization is comprised of active member (as: operational amplifier, source follower etc.), make image element circuit can not be subject to the impact of coupling capacitance and electric current weight partition effect in element during data voltage in transmission, and allow the rough image data voltage that equals of voltage of display element.If the voltage follow module can slightly reduce the pixel voltage value because of the pressure drop voltage of itself in transmitting procedure, also can increase an actuating switch, make pixel voltage more approach the data voltage value.
Although the present invention discloses as above with embodiment; so it is not in order to limit the present invention, those skilled in the art, under the premise without departing from the spirit and scope of the present invention; can do some changes and retouching, therefore protection scope of the present invention is as the criterion with claim of the present invention.
Claims (14)
1. the image element circuit of a display device comprises:
One first write switch, its first end is coupled to a data line, and this first write switch is controlled by one first switching voltage;
One first write storage unit, it is coupled to the second end of this first write switch, and wherein this first write storage unit stores one first data voltage via this first write switch;
One first voltage follow module, its input end is coupled to this first write storage unit, be stored in this first data voltage of this first write storage unit in order to detection, and produce one first corresponding output end voltage according to testing result in the output terminal of this first voltage follow module, wherein the output terminal of this first voltage follow module is controlled by a second switch voltage, and this first switching voltage is high level from this second switch voltage during different sequential; And
One display element, couple the output terminal of this first voltage follow module, in order to during a picture, via this first voltage follow module, to receive this first output end voltage.
2. the image element circuit of display device as claimed in claim 1, wherein this first voltage follow module comprises:
One first voltage follower, its input end becomes the input end of this first voltage follow module; And
One first display switch, its first end is coupled to the output terminal of this first voltage follower, and the second end of this first display switch becomes the output terminal of this first voltage follow module, and this first display switch is controlled by this second switch voltage.
3. the image element circuit of display device as claimed in claim 2, wherein this first voltage follower comprises an operational amplifier, its first input end becomes the input end of this first voltage follower, and the output terminal of this operational amplifier is coupled to the second input end of this operational amplifier and becomes the output terminal of this first voltage follower.
4. the image element circuit of display device as claimed in claim 2, wherein this first voltage follower comprises the one source pole follower.
5. the image element circuit of display device as claimed in claim 1, wherein this first voltage follow module comprises:
One first voltage follower, its input end becomes the input end of this first voltage follow module, and the output terminal of this first voltage follower becomes the output terminal of this first voltage follow module; And
One first power control switch, its first end is coupled to the power input of this first voltage follower, and the second termination of this first power control switch is received a system voltage, and this first power control switch is controlled by this second switch voltage.
6. the image element circuit of display device as claimed in claim 5, wherein this first voltage follower comprises an operational amplifier, its first input end becomes the input end of this first voltage follower, and the output terminal of this operational amplifier is coupled to the second input end of this operational amplifier and becomes the output terminal of this first voltage follower.
7. the image element circuit of display device as claimed in claim 1, wherein this first write storage unit comprises one first electric capacity, and its first end is coupled to the second end of this first write switch, and the second termination of this first electric capacity is received one first reference voltage.
8. the image element circuit of display device as claimed in claim 1, also comprise a demonstration storage unit, and it is coupled to the output terminal of this first voltage follow module.
9. the image element circuit of display device as claimed in claim 8, wherein this demonstration storage unit comprises one second electric capacity, and its first end is coupled to the output terminal of this voltage follow module, and the second termination of this second electric capacity is received one second reference voltage.
10. the image element circuit of display device as claimed in claim 1, also comprise one first actuating switch, its first end is coupled to this first write storage unit, and the second end of this first actuating switch is coupled to this display element, and this first actuating switch is controlled by one first forward voltage.
11. the image element circuit of display device as claimed in claim 1 also comprises:
One second write switch, its first end is coupled to this data line, and this second write switch is controlled by one the 3rd switching voltage;
One second write storage unit, it is coupled to the second end of this second write switch, and wherein this second write storage unit stores one second data voltage via this second write switch;
One second voltage is followed module, its input end is coupled to this second write storage unit, the output terminal that this second voltage is followed module is coupled to this display element, be stored in this second data voltage of this second write storage unit in order to detection, and the output terminal of according to testing result, in this second voltage, following module produces one second corresponding output end voltage, the output terminal that wherein this second voltage is followed module is controlled by one the 4th switching voltage.
12. the image element circuit of display device as claimed in claim 11, wherein this second voltage is followed module and is comprised:
One second voltage follower, its input end becomes the input end that this second voltage is followed module; And
One second display switch, its first end is coupled to the output terminal of this second voltage follower, and the second end of this second display switch becomes the output terminal that this second voltage is followed module, and this second display switch is controlled by the 4th switching voltage.
13. the image element circuit of display device as claimed in claim 11, wherein this second voltage is followed module and is comprised:
One second voltage follower, its input end becomes the input end that this second voltage is followed module, and the output terminal of this second voltage follower becomes the output terminal that this second voltage is followed module; And
One second source gauge tap, its first end is coupled to the power input of this second voltage follower, and the second termination of this second source gauge tap is received a system voltage, and this second source gauge tap is controlled by the 4th switching voltage.
14. the image element circuit of display device as claimed in claim 11, also comprise one second actuating switch, its first end is coupled to this second write storage unit, and the second end of this second actuating switch is coupled to this display element, and this second actuating switch is controlled by one second forward voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010264049 CN102376239B (en) | 2010-08-25 | 2010-08-25 | Pixel circuit of display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201010264049 CN102376239B (en) | 2010-08-25 | 2010-08-25 | Pixel circuit of display device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102376239A CN102376239A (en) | 2012-03-14 |
| CN102376239B true CN102376239B (en) | 2013-12-18 |
Family
ID=45794776
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201010264049 Active CN102376239B (en) | 2010-08-25 | 2010-08-25 | Pixel circuit of display device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102376239B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108877655A (en) * | 2018-07-03 | 2018-11-23 | 深圳吉迪思电子科技有限公司 | A kind of pixel circuit, display screen and electronic equipment |
| CN109920361B (en) * | 2019-04-15 | 2021-02-02 | 京东方科技集团股份有限公司 | Pixel circuit, driving method thereof, array substrate and display device |
| CN111627394B (en) * | 2020-06-30 | 2021-10-22 | 京东方科技集团股份有限公司 | Control circuit, driving method thereof and display device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6331844B1 (en) * | 1996-06-11 | 2001-12-18 | Kabushiki Kaisha Toshiba | Liquid crystal display apparatus |
| TW548625B (en) * | 2000-11-30 | 2003-08-21 | Toshiba Corp | Display apparatus and its driving method |
| CN1479883A (en) * | 2002-02-06 | 2004-03-03 | ������������ʽ���� | Image display unit |
| TW582009B (en) * | 2002-06-28 | 2004-04-01 | Au Optronics Corp | Driving circuit of display device |
-
2010
- 2010-08-25 CN CN 201010264049 patent/CN102376239B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6331844B1 (en) * | 1996-06-11 | 2001-12-18 | Kabushiki Kaisha Toshiba | Liquid crystal display apparatus |
| TW548625B (en) * | 2000-11-30 | 2003-08-21 | Toshiba Corp | Display apparatus and its driving method |
| CN1479883A (en) * | 2002-02-06 | 2004-03-03 | ������������ʽ���� | Image display unit |
| TW582009B (en) * | 2002-06-28 | 2004-04-01 | Au Optronics Corp | Driving circuit of display device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102376239A (en) | 2012-03-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11328670B2 (en) | Pixel circuit, driving method thereof, and display apparatus | |
| US10262566B2 (en) | Shift register, gate driving circuit and display apparatus | |
| US8314764B2 (en) | Voltage amplifier and driving device of display device using the voltage amplifier | |
| CN101191923B (en) | Liquid crystal display system and relevant driving process capable of improving display quality | |
| US9898984B2 (en) | GOA circuit, display device and drive method of GOA circuit | |
| WO2017092514A1 (en) | Shift register unit and drive method therefor, and display apparatus | |
| US10311783B2 (en) | Pixel circuit, method for driving the same, display panel and display device | |
| CN103489425B (en) | Level shifting circuit, array base palte and display device | |
| US20100245298A1 (en) | Shift register capable of reducing coupling effect | |
| US8957842B2 (en) | Pixel circuitry of display device | |
| US8482502B2 (en) | Common voltage generator, display device including the same, and method thereof | |
| US20150170592A1 (en) | Display devices with enhanced driving capability and reduced circuit area of driving circuit | |
| US9978326B2 (en) | Liquid crystal display device and driving method thereof | |
| US10714046B2 (en) | Display driver, electro-optical device, and electronic apparatus | |
| US20110050665A1 (en) | Source driver and compensation method for offset voltage of output buffer thereof | |
| CN102087839B (en) | Device and method for driving liquid crystal display device | |
| CN102376239B (en) | Pixel circuit of display device | |
| US20220254291A1 (en) | Display panel and display device | |
| KR101782641B1 (en) | Liquid crystal display | |
| CN101311782B (en) | Gray scale voltage generation circuit and its operation method | |
| TWI415062B (en) | Driving device of flat panel display and driving method thereof | |
| US11211027B2 (en) | Driving circuit of display panel, driving method thereof, and display panel | |
| TWI431583B (en) | Pixel circuitry of display device | |
| CN108665837B (en) | Scanning driving circuit, driving method thereof and flat panel display device | |
| US8847872B2 (en) | Display for driving a pixel circuitry with positive and negative polarities during a frame period and pixel circuitry |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |