CN102376239A - Pixel circuit of display device - Google Patents
Pixel circuit of display device Download PDFInfo
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- CN102376239A CN102376239A CN201010264049XA CN201010264049A CN102376239A CN 102376239 A CN102376239 A CN 102376239A CN 201010264049X A CN201010264049X A CN 201010264049XA CN 201010264049 A CN201010264049 A CN 201010264049A CN 102376239 A CN102376239 A CN 102376239A
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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: LCD (Liquid Crystal Display; LCD) etc.; It has that high image quality, volume are little, in light weight, low driving voltage, with advantage such as low consumpting power, therefore be widely used in shoot with video-corder projector, personal digital assistant (Personal Digital Assistant, PDA), in consumer communication such as mobile phone, mobile computer, desktop PC display screen and slim DTV or the electronic product; And (Cathode Ray Tube CRT) becomes the mainstream technology of display to replace cathode-ray tube (CRT) gradually.
In general flat display apparatus framework, two-d display panel is made up of pel array, and pel array comprises a plurality of image element circuits.Image element circuit in the past mainly is made up of passive devices such as electric capacity, switches; Therefore when transmitting the image data signal, has charge redistribution (chargesharing) effect unavoidablely; Make the data signals that display element received in the image element circuit that a little drop arranged; Cause its pixel that shows to produce the situation beyond the expection, such as: desired pixel grey scale has a little deviation, distortion and inaccurate or the like on pixel gray-scale displayed and the data signals.The charge redistribution effect often betides on the DLC(digital logic circuit), because element internal has coupling capacitance, thereby can reduce the magnitude of voltage of desiring output voltage or signal in the circuit.
Summary of the invention
The present invention provides a kind of image element circuit of display device; Make the pixel voltage value of image element circuit approach the image data voltage that is received; Let image element circuit when transmission image data voltage verily transfer overvoltage to display element, to reduce the influence of coupling capacitance and electric current weight partition effect in the element.
The present invention proposes a kind of image element circuit of display device, comprises first write switch, first write storage unit, the first voltage follow module and a display element.First end of first write switch is coupled to a data line, and first write switch is controlled by one first switching voltage.First write storage unit is coupled to second end of first write switch, and wherein first write storage unit stores first data voltage via first write switch.The input end of the first voltage follow module is coupled to first write storage unit; Be stored in first data voltage of first write storage unit in order to detection; And according to output terminal generation corresponding first output end voltage of testing result in 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, to receive first output end voltage via the first voltage follow module.
In one embodiment of this invention, the first above-mentioned voltage follow module comprises first voltage follower and first display switch.The input end of first voltage follower becomes the input end of the first voltage follow module.First end of first display switch is coupled to the output terminal of first voltage follower, and its second end becomes the output terminal of the first voltage follow module, and first display switch then 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 first voltage follower, and the output terminal of operational amplifier is coupled to second input end of operational amplifier and becomes the output terminal of 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 first termination of the first transistor is received a system voltage, and its second end becomes the output terminal of source follower.The control end of transistor seconds receives a control voltage, and first termination of transistor seconds is received a common voltage, and second end of transistor seconds is coupled to second end of the first transistor.
In one embodiment of this invention, the first above-mentioned voltage follow module comprises first voltage follower and first power control switch.The input end of first voltage follower becomes the input end of the first voltage follow module, and the output terminal of first voltage follower becomes the output terminal of the first voltage follow module.First end of first power control switch is coupled to the power input of first voltage follower, and second termination of first power control switch is received system voltage, and first power control switch then is controlled by second switch voltage.
In one embodiment of this invention, comprise that also one shows 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 second termination of 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 first write storage unit, and second end of first actuating switch is coupled to display element, and first actuating switch is controlled by the first conducting signal.
In one embodiment of this invention, also comprise second write switch, second write storage unit and the second voltage follow module.First end of second write switch is coupled to data line, and second write switch is controlled by the 3rd switching voltage.Second write storage unit is coupled to second end of second write switch, and wherein second write storage unit stores one second data voltage via second write switch.The input end of the second voltage follow module is coupled to first end of second write storage unit; The output terminal of the second voltage follow module then is coupled to display element; Be stored in second data voltage of second write storage unit in order to detection, and produce one second corresponding output end voltage in the output terminal of the second voltage follow module according to testing result.Wherein, the output terminal of the second voltage follow module is controlled by the 4th switching voltage.
In one embodiment of this invention, the second above-mentioned voltage follow module comprises second voltage follower and second display switch.The input end of second voltage follower becomes the input end of the second voltage follow module.First end of second display switch is coupled to the output terminal of second voltage follower, and second end of second display switch becomes the output terminal of the second voltage follow module, and second display switch is controlled by the 4th switching voltage.
Based on above-mentioned; Embodiments of the invention utilize the voltage follower of being made up of active member (as: operational amplifier, source follower etc.); Make image element circuit let in transmission the voltage of display element is rough to equal image data voltage during data voltage, and can not receive the influence of coupling capacitance and electric current weight partition effect element in.
For making the above-mentioned feature and advantage of the present invention can be more obviously understandable, hereinafter is special lifts embodiment, and is described with reference to the accompanying drawings as follows.
Description of drawings
Fig. 1 is the synoptic diagram that a kind of image element circuit of display device is described according to first embodiment of image element circuit.
Fig. 2 is the driving sequential chart that a kind of image element circuit of display device is described according to first embodiment of image element circuit.
Fig. 3 is the synoptic diagram that a kind of image element circuit of display device is described according to second embodiment of the invention.
Fig. 4 is the driving sequential chart that a kind of image element circuit of display device is described according to second embodiment of the invention.
Fig. 5 is the synoptic diagram that a kind of image element circuit of display device is described according to third embodiment of the invention.
Fig. 6 is the driving sequential chart that a kind of image element circuit of display device is described according to third embodiment of the invention.
Fig. 7 is the circuit diagram that a kind of image element circuit of display device is described according to fourth embodiment of the invention.
Fig. 8 is the circuit diagram that first voltage follower is described according to fourth embodiment of the invention.
Fig. 9 is the circuit diagram that second display switch is described according to fourth embodiment of the invention.
Figure 10 is the circuit diagram that a kind of image element circuit of display device is described according to fifth embodiment of the invention.
Figure 11 is the circuit diagram that a kind of image element circuit of display device is described according to sixth embodiment of the invention.
Figure 12 is the synoptic diagram that the image element circuit of another kind of display device is described according to the 7th embodiment of image element circuit.
Figure 13 is the driving sequential chart that the image element circuit of another kind of display device is described according to the 7th embodiment of image element circuit.
Figure 14 is the synoptic diagram that the image element circuit of another kind of display device is described according to eighth embodiment of the invention.
Figure 15 is the synoptic diagram that the image element circuit of another kind of display device is described according to nineth 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 the demonstration
130: the first display switch T4: wait to be written during
140: show storage unit T5: conduction period
Write at 150: display element T6: first/second show during
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: first forward voltage
1430: the second display switch Vto2: second forward voltage
1460: the second voltage follow module Vsw1: first switching voltage
1470: the second voltage follower Vsw2: second reference voltage
1580: the second actuating switch Vref1: first reference voltage
A, B, C: the first input end of operational amplifier, second input end and output terminal
Cs1: the first electric capacity Vref2: 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 first embodiment of the image element circuit 100 of display device in this proposition, please with reference to Fig. 1.Fig. 1 is the synoptic diagram that a kind of image element circuit 100 of display device is described according to first embodiment of image element circuit 100.The image element circuit 100 of display device comprises first write switch 110, first write storage unit 120, first display switch 130 and display element 150.First end of first write switch 110 is coupled to a data line DataLine, and 110 of first write switches are controlled by one first switching voltage Vsw1.First end of first write storage unit 120 is coupled to second end of first write switch 110, and its second end then receives one first reference voltage Vref 1.Wherein, first write storage unit 120 stores one first data voltage via first write switch 110.First end of first display switch 130 is coupled to first write storage unit 120, and wherein first display switch 130 is controlled by a second switch voltage Vsw2.Display element 150 is coupled to second end of first display switch 130, and the other end of display element 150 then receives common voltage Vcom.Display element 150 receives first data voltage that is stored by first write storage unit 120 via second switch voltage Vsw2 during a picture.
In present embodiment, image element circuit 100 also comprises demonstration storage unit 140, and its first end is coupled to second end of first display switch 130, shows that second end of storage unit 140 then receives second reference voltage Vref 2.In present embodiment, display element 150 for example is a liquid crystal capacitance 150.This liquid crystal capacitance 150 drives and changes the liquid crystal angle in the liquid crystal capacitance 150 by the potential difference (PD) of pixel voltage Vlc and common voltage Vcom.
For specifying the mode of operation of present embodiment, please be simultaneously with reference to Fig. 1 and Fig. 2.Fig. 2 is the driving sequential chart that a kind of image element circuit 100 of display device is described according to first embodiment of image element circuit 100.Below voltage that first write storage unit 120 is coupled on first write switch, 110 second ends be called end-point voltage Vn.Said according to present embodiment, mainly be divided into four periods during driving each picture of sequential: T1 during writing, etc. to be shown during T2, show during T3 with etc. to be written during T4.T1 is the period that the first switching voltage Vsw1 is positioned at high level during writing, and this moment, second switch voltage Vsw2 was a low level.Therefore, T1 also is that first write switch 110 is positioned at conducting state during writing, and first display switch 130 then is positioned at the period of cut-off state.The first capacitor C s1 in first write storage unit 120 receives the first data voltage V1 via the data line DataLine place of first write switch 110; Therefore the first capacitor C s1 is convenient to store charge this moment, and makes end-point voltage Vn equal the first data voltage V1.Be that " end-point voltage Vn equals the first data voltage V1 " is the circuit analysis result who is positioned under the ideal state what this paid special attention to.And in actual state, if when considering the circuits/devices of non-ideal characteristic, end-point voltage Vn can be less than the first data voltage V1.
Then get into etc. to be shown during T2.Etc. T2 during to be shown is the first switching voltage Vsw1 and second switch voltage Vsw2 when all being positioned at low level, also is the period that first write switch 110 and first display switch 130 all are positioned at cut-off state.This moment, the first capacitor C s1 in first write storage unit 120 maintains the first data voltage V1 with the magnitude of voltage of end-point voltage Vn.
Afterwards, T3 then is positioned at the period of high level during the demonstration for second switch voltage Vsw2, and the first switching voltage Vsw1 then is a low level.In view of the above, T3 also is that first display switch 130 is in conducting state during the demonstration, and first write switch 110 then is in the period of cut-off state.On the ideal, the first stored data voltage V1 of the first capacitor C s1 should verily be transferred into display element 150.That is to say that after 130 conductings of first display switch, 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 to be evenly distributed in the first capacitor C s1, to show among the second capacitor C s2 and liquid crystal capacitance 150 in the storage unit 140, cause the pixel voltage Vlc of display element 150 to be not equal to the first data voltage V1 in the stored electric charge of the first capacitor C s1.That is to say, produce a voltage difference delta V between the pixel voltage Vlc and the first data voltage V1.For the situation beyond the expection reduce to take place the pixel that makes display circuit 100, for example: pixel gray-scale displayed and the first data voltage V1 upward desired pixel grey scale have a little deviation, distortion and inaccurate or the like, and voltage difference delta V must be as best one can little.
Then get into etc. to be written during T4.Etc. T4 during to be written with etc. to be shown during the state of T2 similar, the first switching voltage Vsw1 and the second switch voltage Vsw2 of this moment all are positioned at low level, and first write switch 110 and first display switch 130 all are positioned at cut-off state.Therefore, driving the required potential difference (PD) of liquid crystal capacitance 150 will be by showing that storage unit 140 and liquid crystal capacitance 150 itself continue to provide, and T1 arrives during waiting for the writing of next picture.In other embodiments, show that storage unit 140 can be omitted because of design requirement, and itself preserve data voltage by liquid crystal capacitance 150.
According to present embodiment, image element circuit 100 will make the pixel voltage Vlc and the first data voltage V1 that drive liquid crystal capacitance 150 have voltage difference delta V, cause liquid crystal capacitance 150 can't correctly change the angle of its liquid crystal according to the first data voltage V1.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 capacitance of liquid crystal capacitance 150, when the heavy partition effect of electric capacity takes place, to reduce the fall of voltage difference delta V.But owing to the restriction of technology and volume-diminishedization 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.
Said before the certificate, second embodiment according to the invention is proposed to reduce voltage difference delta V and to reduce the charge redistribution effect, please with reference to Fig. 3 at this.Fig. 3 is the synoptic diagram that a kind of image element circuit 300 of display device is described according to second embodiment of the invention.Image element circuit 300 comprises first write switch 110, first write storage unit 120, the first voltage follow module 360 and display element 150.Wherein, present embodiment is similar with the image element circuit 100 of above-mentioned first embodiment, and therefore identical coupling mode and operation instructions repeats no more at this.In order to offer some clarification on present embodiment; Be called end-point voltage Vn1 at this input terminal voltage with the first voltage follow module 360; And the output terminal of the first voltage follow module 360 is coupled to liquid crystal capacitance 150, and therefore 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 understand the present invention more, below explain, so the identical operations mode repeats no more at this to the difference of mode of operation in the image element circuit 300 of the image element circuit of Fig. 1 100 and Fig. 3.Please with reference to Fig. 4, Fig. 4 is the driving sequential chart that a kind of image element circuit 300 of display device is described according to second embodiment of the invention.Among the T3, this moment, second switch voltage Vsw2 was positioned at high level during the demonstration during each picture, and the first switching voltage Vsw1 then is a low level.In view of the above, first display switch 130 also is in conducting state during T3 during showing, and first write switch 330 in the first voltage follow module 360 is in cut-off state.By knowing in the previous narration; The input terminal voltage of the first voltage follow module 360 (that is end-point voltage Vn1) utilizes the first capacitor C s1 in first writing memory element 120 keeping magnitude of voltage, and this moment end-point voltage Vn1 magnitude of voltage equal the first data voltage V1.Be that " end-point voltage Vn1 equals the first data voltage V1 " is the circuit analysis result who is positioned under the ideal state what this paid special attention to.In actual state, if when considering the circuits/devices of non-ideal characteristic (for example considering the pressure drop of first write switch 110), end-point voltage Vn1 can be less than the first data voltage V1.
Under ideal state, first voltage follower 370 in the first voltage follow module 360 can produce corresponding first output end voltage (it also is the first data voltage V1) according to end-point voltage Vn1 (its magnitude of voltage is the first data voltage V1).Yet if when considering first voltage follower 370 of non-ideal characteristic, the magnitude of voltage of the magnitude of voltage of first output end voltage and the first data voltage V1 is possible different.Therefore; When first display switch 330 is in conducting state; The output terminal of first voltage follower 370 can be coupled to display element 150, makes rough first output end voltage (that is first data voltage V1) that equals first voltage follower 370 of pixel voltage Vlc.Show memory element 140 also during showing among the T3 store charge to keep the first data voltage V1.
Then, in etc. to be written during during T4, first write switch 110 and 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; 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 T1 arrives during waiting for writing during the next picture.
Utilize the first voltage follow module 360 to come verily to transfer to display element 150 to the first data voltage V1 from the input end of the first voltage follow module 360 in the present embodiment, reduce voltage difference delta V by this.On the ideal, the output end voltage of first voltage follower 370 can be set at and equal 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).In other embodiment, can come the aforementioned two-end-point of conducting,, make pixel voltage Vlc, just further reduce voltage difference delta V more near target voltage (i.e. the first data voltage V1) to improve aforementioned output error (or skew) by increasing a transmitting switch.Please with reference to Fig. 5 and Fig. 6.Fig. 5 is the synoptic diagram that a kind of image element circuit 500 of display device is described according to third embodiment of the invention, and Fig. 6 is the driving sequential chart that a kind of image element circuit 500 of display device is described according to third embodiment of the invention.Wherein, present embodiment is similar with the image element circuit 300 of aforementioned second embodiment, and therefore identical coupling mode and operation instructions repeats no more at this.
The difference of second embodiment of present embodiment and Fig. 3 is; Image element circuit 500 also comprises one first actuating switch 580; Its first end is coupled to first write storage unit 120; Second end of 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 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; First output end voltage of the first voltage follow module 360 (being pixel voltage Vlc) should equal first input end voltage Vn1 (i.e. the first data voltage V1) on ideal, deduct the offset voltage Vt that the first voltage follow module 360 includes but actual pixel voltage Vlc equals the first data voltage V1.If the voltage difference delta V of the first data voltage V1 and pixel voltage Vlc when T3 (during showing Δ V=Vt) excessive to ignoring its influence, present embodiment is convenient more to be dwindled voltage difference delta V with first actuating switch 580, below detailed description.
According to the above, present embodiment in drive sequential etc. increase conduction period T5 among the T4 during to be written, this moment, the first forward voltage Vto1 was positioned at noble potential.By this, first actuating switch 580 just is in conducting state, and first write switch 110 and first display switch 330 all are positioned at cut-off state.This moment, the two ends of first actuating switch 580 link to each other and cause the charge redistribution effect, make pixel voltage Vlc more near the first data voltage V1, and let voltage difference delta V more dwindle.
Below for more specifying embodiments of the invention, the circuit framework in this details the first voltage follow module 360 is please with reference to Fig. 7.Fig. 7 is the circuit diagram that a kind of image element circuit 700 of display device is described according to fourth embodiment of the invention.Present embodiment is similar with the image element circuit 500 of aforementioned the 3rd embodiment, and therefore identical coupling mode and operation instructions repeats no more at this.
Difference is; 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 first voltage follower 370.By this, operational amplifier OP detects the magnitude of voltage (that is end-point voltage Vn1) on the first input end A, and produces the correspondent voltage value in output terminal C, to realize the purpose of present embodiment.Use circuit design that the present embodiment person can realize this operational amplifier OP according to its demand to realize aforesaid identical function.
In present embodiment, the detailed circuit diagram of operational amplifier OP is illustrated in Fig. 8.Fig. 8 is the circuit diagram that first voltage follower 370 is described 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 present embodiment; PMOS) transistor; The 3rd computing transistor M3 and the 4th computing transistor M4 then are N NMOS N-channel MOS N (N-channel metal oxide semiconductor, NMOS) transistor.
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.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.First end of the 3rd computing transistor M3 (for example drain electrode end) is coupled to the transistorized control end of first computing (for example gate terminal), and its second end (for example source terminal) then 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.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 second end (for example drain electrode end) of the second computing transistor M2; To become the output terminal of operational amplifier OP, 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 and implemented for those skilled in the art easily, do not add to give unnecessary details at this.Use visual its demand of present embodiment person and replace aforementioned operational amplifier OP, to realize the purpose of present embodiment by this with the operational amplification circuit of identical function.
In addition, use the present embodiment person and also can design first write switch 110, first display switch 330 and first actuating switch 580, with the realization above-mentioned functions according to its demand.Is example at this with first display switch 330, and please with reference to Fig. 9, Fig. 9 is the circuit diagram that first display switch 330 is described according to fourth embodiment of the invention.First display switch 330 for example is made up 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 and implemented for those skilled in the art easily, and in other embodiment, can also realize first display switch 330 by single transistor, do not add to give unnecessary details at this.
In other embodiment, first voltage follower 370 can also utilize source follower (sourcefollower) to realize, please with reference to Figure 10.Figure 10 is the circuit diagram that the image element circuit of another kind of display device is described according to fifth embodiment of the invention.Present embodiment is similar with aforementioned the 3rd embodiment, and therefore identical coupling mode and operation instructions repeats no more at this.The source follower of first voltage follower 370 comprises the first transistor MN1 and transistor seconds MN2 in the image element circuit 1000.
In present embodiment, the first transistor MN1 and transistor seconds MN2 for example are the NOMS transistors.The control end of the first transistor MN1 becomes the input end of source follower 370, and first termination of the first transistor MN1 is received a system voltage Vss, and second end of the first transistor MN1 becomes the output terminal of source follower 370.The control end of transistor seconds MN2 receives a control voltage VB, and its first termination is received common voltage Vcom, and second end of transistor seconds MN2 is coupled to 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 and just controls first actuating switch 580 as the first conducting signal Vto1 capable of using as Fig. 6; Dwindling the voltage difference delta V of the first data voltage V1 and pixel voltage Vlc, and realize the purpose of 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; Second switch voltage Vsw2 also capable of using controls the power supply supply of operational amplifier OP to realize above-mentioned purpose, please with reference to Figure 11.Figure 11 is the circuit diagram that a kind of image element circuit of display device is described according to sixth embodiment of the invention.
The first voltage follow module 360 of image element circuit 1100 comprises first voltage follower 370, first power control switch 1110 and first power control switch 1120.The input end of first voltage follower 370 becomes the input end of the first voltage follow module 360, and the output terminal of first voltage follower 370 becomes the output terminal of the first voltage follow module 360.First end of first power control switch 1110 is coupled to the power input of first voltage follower 370, and second termination of first power control switch 1110 is received system voltage Vss.And first end of first power control switch 1120 is coupled to the ground connection input end of first voltage follower 370, and second end of first power control switch 1110 then receives common voltage Vcom.
Wherein, first power control switch 1110 and first power control switch 1120 all are controlled by second switch voltage Vsw2.Because first voltage follower 370 is made up of active member (as: operational amplifier OP, source follower etc.), therefore can rely on the power supply of controlling active member and first output end voltage of controlling first voltage follower 370 by this in present embodiment.Therefore, as second switch voltage Vsw2 during in low level, first power control switch 1110 and first power control switch 1120 become cut-off state, and first voltage follower 370 just can't produce first output end voltage.Relatively; As second switch voltage Vsw2 during in high level; First power control switch 1110 and first power control switch 1120 become conducting state by this; First voltage follower 370 could come into operation by power supply, realizes the function of present embodiment to control the pixel voltage Vlc on the display element 150 further.
With another viewpoint, at this another kind of the 7th embodiment that meets the image element circuit 1200 of display device is proposed, please with reference to Figure 12 and Figure 13.Figure 12 is the synoptic diagram that the image element circuit 1200 of another kind of display device is described according to the 7th embodiment of image element circuit 1200.Figure 13 is the driving sequential chart that the image element circuit 1200 of another kind of display device is described according to the 7th embodiment of image element circuit 1200.Image element circuit 1200 also comprises second write switch 1210, second write storage unit 1220 and second display switch 1230 except having first write switch 110, first write storage unit 120, first display switch 130 and display element 150.
First end of second write switch 1210 is coupled to data line DataLine, and second write switch 1210 is controlled by the 3rd switching voltage, and the 3rd switching voltage equals second switch voltage Vsw2 in present embodiment.Second write storage unit 1220 is coupled to second end of second write switch 1210, and wherein second write storage unit 122 stores second data voltage via second write switch 1210.First end of second display switch 1230 is coupled to second write storage unit 1220, and wherein first display switch 1230 is controlled by the 4th switching voltage, and the 4th switching voltage equals the first switching voltage Vsw1 in present embodiment.In addition, image element circuit 1200 also comprises demonstration storage unit 140, comprises one second capacitor C s2 in it, and other thin portions explanations of present embodiment have been included among above-mentioned each embodiment, so do not repeat them here.
Mode of operation and flow process at this pixels illustrated circuit 1200.For offering some clarification on present embodiment, be called the first end-point voltage Vn1 at this voltage, and the voltage of second write storage unit, 1,220 first ends is called the second end-point voltage Vn2 first write storage unit, 120 first ends.In the described driving sequential of present embodiment; Per 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 write/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, first write switch 110 and second display switch 1230 are positioned at conducting state, and first display switch 130 and first write switch 1210 then are positioned at cut-off state.The first capacitor C s1 in first write storage unit 120 receives the first data voltage V1 via the data line DataLine place of first write switch 110, makes the end-point voltage Vn1 that wins equal the first data voltage V1.
The 3rd capacitor C s3 in second write storage unit 1220 will write the stored second data voltage V2 (i.e. the second end-point voltage Vn2) of T8 in period in previous first demonstration/the second and be sent to liquid crystal capacitance 150.On the ideal, the first stored data voltage V1 of the first capacitor C s1 should verily be transferred into display element 150.Yet, because the charge redistribution effect produces a voltage difference delta V2 between the feasible in fact pixel voltage Vlc of display element 150 (or second end-point voltage Vn2) and the second data voltage V2.This moment, liquid crystal capacitance 150 showed the pixel of first picture by pixel voltage Vlc.
Then get into first latch during T7, this moment, the first switching voltage Vsw1 and second switch voltage Vsw2 all were positioned at low level.Therefore, first write switch 110, second write switch 1210, first display switch 130 and second display switch 1230 all are positioned at cut-off state.This moment, the first capacitor C s1 in first write storage unit 120 maintains the first data voltage V1 with the magnitude of voltage of the first end-point voltage Vn1.Showing that storage unit 140 and coupling capacitances in the liquid crystal capacitance 150 continue to keep drives the required potential difference (PD) of liquid crystal capacitance 150, lets liquid crystal capacitance 150 continue to show the pixels of first pictures.In other embodiments, show that storage unit 140 can be omitted because of design requirement, and itself preserve data voltage by liquid crystal capacitance 150.
Afterwards, get into first and show that/the second writes T8 in period.This moment, second switch voltage Vsw2 was positioned at high level, and the first switching voltage Vsw1 then is a low level.In view of the above, show that in first/the second writes period during T8, first display switch 130 and second write switch 1210 are in conducting state, and first write switch 110 and second display switch 1230 then are in cut-off state.This moment is because the heavy partition effect of electric capacity makes the pixel voltage Vlc (i.e. the first end-point voltage Vn1) of display element 150 and the first data voltage V1 produce a voltage difference delta V1.This moment, liquid crystal capacitance 150 showed the pixel of second picture by pixel voltage Vlc.
Then get into second latch during T9.Second latch during T9 and first latch during the state of T7 similar, first write switch 110, second write switch 1210, first display switch 130 and second display switch 1230 all are positioned at cut-off state.Therefore, the 3rd capacitor C s3 in second write storage unit 1220 maintains the second data voltage V2 with the magnitude of voltage of end-point voltage Vn2.Showing that coupling capacitances in storage unit 140 and the liquid crystal capacitance 150 then continue to keep drives the required potential difference (PD) of liquid crystal capacitance 150, makes liquid crystal capacitance 150 continue to show the pixels of second picture, and wait for next first write/second show during T6 arrive.
Said before the certificate; In order to dwindle voltage difference delta V1 and voltage difference delta V2 as best one can; And reduce the influence that the charge redistribution effect is brought; At this 8th embodiment according to the invention is proposed, so that image element circuit is in transmission transfer overvoltage to liquid crystal capacitance 150 verily during data voltage, please with reference to Figure 14 and Figure 15.Figure 14 is the synoptic diagram that the image element circuit of another kind of display device is described according to eighth embodiment of the invention.Figure 15 is the synoptic diagram that the image element circuit of another kind of display device is described according to nineth 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 and the second voltage follow module 1430 to come Data transmission voltage to liquid crystal capacitance 150 verily, make the pixel voltage value of image element circuit approach the data voltage that is received.The input end of the first voltage follow module 360 is coupled to first write storage unit 120, and its output terminal is coupled to display element 150.The input end of the second voltage follow module 1460 then is coupled to second write storage unit 1220, and its output terminal also is coupled to display element 150.
In addition; For solving the in fact first voltage follow module 360 and the second voltage follow module, 1430 interior output error or the offset voltages that had; More add first actuating switch 580 and second actuating switch 1580 among the 9th embodiment; To improve aforementioned output error (or offset voltage), make pixel voltage Vlc more near target voltage (i.e. the first data voltage V1 or the second data voltage V2), just further reduce voltage difference delta V1 and voltage difference delta V2.Wherein first end of second actuating switch 1,580 second end that is coupled to 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, the 8th embodiment has been included among above-mentioned each embodiment, so do not repeat them here with other identical or similar thin portion flow processs of the 9th embodiment.
In sum; Embodiments of the invention utilize the voltage follow module of being made up of active member (as: operational amplifier, source follower etc.); Make image element circuit can not receive the influence of coupling capacitance and electric current weight partition effect in the element during data voltage, and let the rough image data voltage that equals of voltage of display element in transmission.If the voltage follow module can slightly reduce the pixel voltage value because of the pressure drop voltage of itself in transmission course, also can increase an actuating switch, make pixel voltage more near the data voltage value.
Though the present invention discloses as above with embodiment; Right its is not in order to qualification 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, so 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 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 according to output terminal generation corresponding one first output end voltage of testing result in this first voltage follow module, wherein the output terminal of this first voltage follow module is controlled by a second switch voltage; And
One display element couples the output terminal of this first voltage follow module, in order to during a picture, to receive this first output end voltage via this first voltage follow module.
2. the image element circuit of display device according to claim 1, wherein this first voltage follow module comprises:
One first voltage follower, its input end become 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 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. like the image element circuit of the said display device of 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 second input end of this operational amplifier and becomes the output terminal of this first voltage follower.
4. like the image element circuit of the said display device of claim 2, wherein this first voltage follower comprises the one source pole follower.
5. the image element circuit of display device according to claim 1, wherein this first voltage follow module comprises:
One first voltage follower, its input end become 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 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. like the image element circuit of the said display device of 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 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 according to claim 1, wherein this first write storage unit comprises one first electric capacity, and its first end is coupled to second end of this first write switch, and second termination of this first electric capacity is received one first reference voltage.
8. the image element circuit of display device according to claim 1 comprises that also one shows storage unit, and it is coupled to the output terminal of this first voltage follow module.
9. like the image element circuit of the said display device of 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 second termination of this second electric capacity is received one second reference voltage.
10. the image element circuit of display device according to claim 1; Also comprise one first actuating switch; Its first end is coupled to this first write storage unit, and 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 according to 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 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 follow module; Its input end is coupled to this second write storage unit; The output terminal of this second voltage follow 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 produce one second corresponding output end voltage according to testing result in the output terminal of this second voltage follow module, wherein the output terminal of this second voltage follow module is controlled by one the 4th switching voltage.
12. like the image element circuit of the said display device of claim 11, wherein this second voltage follow module comprises:
One second voltage follower, its input end become the input end of this second voltage follow module; And
One second display switch, its first end is coupled to the output terminal of this second voltage follower, and second end of this second display switch becomes the output terminal of this second voltage follow module, and this second display switch is controlled by the 4th switching voltage.
13. like the image element circuit of the said display device of claim 11, wherein this second voltage follow module comprises:
One second voltage follower, its input end become the input end of this second voltage follow module, and the output terminal of this second voltage follower becomes the output terminal of this second voltage follow module; And
One second source CS, its first end is coupled to the power input of this second voltage follower, and second termination of this second source CS is received a system voltage, and this second source CS is controlled by the 4th switching voltage.
14. image element circuit like the said display device of claim 11; Also comprise one second actuating switch; Its first end is coupled to this second write storage unit, and 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.
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| CN 201010264049 CN102376239B (en) | 2010-08-25 | 2010-08-25 | Pixel circuit of display device |
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| CN 201010264049 CN102376239B (en) | 2010-08-25 | 2010-08-25 | Pixel circuit of display device |
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| 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 |
| CN111627394A (en) * | 2020-06-30 | 2020-09-04 | 京东方科技集团股份有限公司 | Control circuit, driving method thereof and display device |
| WO2020211542A1 (en) * | 2019-04-15 | 2020-10-22 | 京东方科技集团股份有限公司 | Pixel circuit and driving method therefor, and array substrate and display device |
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| 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 |
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| TW548625B (en) * | 2000-11-30 | 2003-08-21 | Toshiba Corp | Display apparatus and its driving method |
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| WO2020211542A1 (en) * | 2019-04-15 | 2020-10-22 | 京东方科技集团股份有限公司 | Pixel circuit and driving method therefor, and array substrate and display device |
| CN111627394A (en) * | 2020-06-30 | 2020-09-04 | 京东方科技集团股份有限公司 | Control circuit, driving method thereof 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 |
| US11514865B2 (en) | 2020-06-30 | 2022-11-29 | Chengdu Boe Optoelectronics Technology Co., Ltd. | Driving circuit and driving method thereof, display panel, and display device |
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| CN102376239B (en) | 2013-12-18 |
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