Summary of the invention
The purpose of this invention is to provide a kind of optional screen that changes than low-light level of having showed along with the time.
Therefore, theme of the present invention is a kind of image display screen, comprising:
-optical transmitting set, the capable and optical transmitting set column distribution with optical transmitting set be so that form light emitter arrays,
-control device is used for the luminous of array of controls optical transmitting set, and described control device comprises:
A) be used for first circuit of address light transmitter, be associated with each optical transmitting set in the array and flow through its electric current with control, described circuit comprises:
-the first current modulator is used for to described optical transmitting set power supply, and described first modulator comprises gate electrode and two current-carrying electrodes,
-the first holding capacitor is used to be provided with the electromotive force at the gate electrode place of first current modulator,
B) at least one second circuit each optical transmitting set, that be used for the address light transmitter, described first is associated with identical optical transmitting set in parallel with described second addressing circuit, and described second circuit comprises:
-be used for second current modulator of described optical transmitting set, comprise gate electrode and two current-carrying electrodes,
-the second holding capacitor is used to store the electromotive force at the gate electrode place of second current modulator;
C) addressing control device, be used for applying addressing voltage at described first holding capacitor and the described second holding capacitor place, described addressing voltage presentation video data, and be used to activate first or second addressing circuit, so that provide electric current to optical transmitting set according to described view data
Described screen is characterised in that the addressing control device is provided with bias voltage at described first current modulator or the described second current modulator place, and described bias voltage has the opposite polarity polarity with described addressing voltage.
According to specific embodiment, described display screen comprises one or more in the following feature:
-addressing control device is used at first applying addressing voltage to described first current modulator, so that begin to be used to activate the stage of first addressing circuit, then, applies bias voltage, so that the stage of first addressing circuit that begins to be used to setover;
-addressing control device is used at first applying addressing voltage to described second current modulator, so that begin to be used to activate the stage of second addressing circuit, then, applies bias voltage, so that the stage of second addressing circuit that begins to be used to setover; The stage that is used to activate first addressing circuit is synchronous with the stage of second addressing circuit that is used to setover, and the stage that is used to activate second addressing circuit is synchronous with the stage of first addressing circuit that is used to setover;
-control device comprises device for selection controlling, and described device for selection controlling comprises:
-at first selector switch of each first addressing circuit of optical transmitting set, be used for according to selecting voltage, drive the described grid that described addressing voltage or described bias voltage send to described first holding capacitor and described first current modulator, so that select described optical transmitting set;
-at second selector switch of each second addressing circuit of same light transmitter, be used for according to described selection voltage, drive the described grid that described addressing voltage or described bias voltage send to described second holding capacitor and described second current modulator, so that select described optical transmitting set; And
-drive unit is used to drive first and second selector switch;
-drive unit also comprises: select electrode at first and second of each row optical transmitting set, described first and second select electrode to link to each other with first and second selector switch respectively, so that it is controlled; Select driver element, be used for alternately at first described selection voltage being sent to described first and select electrode, then described selection voltage is sent to described second and select electrode;
-addressing control device comprises: at the addressing electrode of each row optical transmitting set, first and second selector switch link to each other with described addressing electrode; And the addressing driver element, be used for alternately sending described addressing voltage and described bias voltage to described addressing electrode;
-drive unit also comprises: at the selection electrode of each row optical transmitting set, first and second selector switch link to each other so that it is controlled with described selection electrode; And the selection driver element, be used for sending described selection voltage to first and second selector switch concomitantly;
-addressing control device comprises: at first and second addressing electrodes of each row optical transmitting set, described first and second addressing electrodes link to each other with first and second selector switch respectively; And the addressing driver element, be used for sending described addressing voltage or described bias voltage to first addressing electrode and second addressing electrode concomitantly.
Another theme of the present invention is a kind of addressing method that is used for such display screen, in order to drive each optical transmitting set, it is characterized in that comprising:
-be used to activate the stage of first addressing circuit, so that provide electric current to optical transmitting set;
-be used to the stage of second addressing circuit of setovering, so that be offset the activation threshold value voltage of second modulator;
-be used to activate the stage of second addressing circuit, so that provide electric current to optical transmitting set;
-be used to the stage of first addressing circuit of setovering, so that be offset the activation threshold value voltage of first modulator, and
The stage that is used to activate first addressing circuit took place simultaneously with the stage of second addressing circuit that is used to setover, and the stage that is used to activate second addressing circuit took place simultaneously with the stage of first addressing circuit that is used to setover.
According to specific embodiment, described display packing comprises one or more in the following feature:
-to be used to activate after one or more stages of first addressing circuit be that at least one is used to the stage of first addressing circuit of setovering, and to be used to activate after one or more stages of second addressing circuit be the stage of at least one second addressing circuit that is used to setover;
-described method comprises:
-at the addressing programming step of described first holding capacitor, be applied to described capacitor by addressing voltage and realize the presentation video data;
-at the offset programming step of described first current modulator, realize that by bias voltage being applied to described modulator described bias voltage has the opposite polarity polarity of the electromotive force of storing with first holding capacitor;
-at the offset programming step of described second current modulator,, realizes described bias voltage by being applied to described modulator; And
-at the addressing programming step of described second holding capacitor,, realizes described addressing voltage by being applied to described capacitor;
-at after the offset programming step of described first current modulator being addressing programming step at second holding capacitor, and alternately, after the offset programming step at described second current modulator addressing programming step at first holding capacitor; And
-take place simultaneously at the described offset programming step of described second current modulator and described addressing programming step at described first holding capacitor, and take place simultaneously at the described offset programming step of described first current modulator and described addressing programming step at described second holding capacitor.
Embodiment
Display screen according to the present invention is a kind of active matrix screen, comprises with row and column distributing to form the optical transmitting set of light emitter arrays.
The optical transmitting set of display screen is an Organic Light Emitting Diode, is abbreviated as OLED.When screen was monochrome, each optical transmitting set was associated with a pixel, or when screen was polychrome, each optical transmitting set was associated with a sub-pixel.The luminous intensity that the optical transmitting set emission is directly proportional with the electric current that flows through it.
Fig. 1 has represented according to first embodiment of the invention, has been used for the device 2 of the emission of array of controls optical transmitting set 4.For the purpose of simplifying, only illustrate the device of the addressing that is used to control single optical transmitting set among the figure.
Control device 2 comprises: first addressing circuit 6 that links to each other with optical transmitting set in the array 4, be used to control the row addressing of optical transmitting set addressing control device 8, be used to control device for selection controlling 10, control system 11 that the row of optical transmitting set selects and second addressing circuit 12 that also links to each other with optical transmitting set 4.
First addressing circuit 6 comprises: current modulator 14, holding capacitor 16 and selector switch 18.
Modulator 14 and switch 18 are amorphous hydrogenated silicon thin film transistor (TFT)s.More specifically, these are n transistor npn npns.They comprise drain electrode, grid and source electrode, and in the time will being applied between its grid and the source electrode more than or equal to the voltage of its activation threshold value voltage, electric current flows through them from its drain-to-source.
Alternatively, also can use the p transistor npn npn.In this case, transistor 14 and 18 has the electric current that flows through them from its source electrode to drain electrode.
The drain electrode of modulator 14 links to each other with the negative electrode of optical transmitting set 14.The anode of optical transmitting set 4 with to the dc voltage V of its power supply
DdGenerator link to each other.The source electrode of modulator 14 links to each other with ground electrode or negative voltage.The grid of modulator 14 links to each other with the source electrode of switch 18 and the terminal of holding capacitor 16.The another terminal of capacitor 16 links to each other with ground electrode.The grid of switch 18 links to each other with device for selection controlling 10, and its drain electrode links to each other with addressing control device 8.
Addressing control device 8 at the optical transmitting set row comprises addressing electrode 20 and the addressing driver element 22 that is listed as at each optical transmitting set.For a row optical transmitting set, electrode 20 links to each other with the drain electrode of the switch 18 of the driver element 22 and first addressing circuit 6.
Device for selection controlling 10 comprises at the capable first selection electrode 24 and second of each optical transmitting set to be selected electrode 26 and selects driver element 28.For delegation's optical transmitting set, first selects electrode 24 to link to each other with the grid of the switch 18 of the driver element 28 and first addressing circuit 6.For delegation's optical transmitting set, second electrode 26 links to each other with the grid of the switch 38 of the driver element 28 and second addressing circuit 12.
Control system 11 is with addressing driver element 22 and select driver element 28 to link to each other.
Second addressing circuit 12 comprises the assembly identical with first addressing circuit 6, that is, and and current modulator 34, holding capacitor 36 and selector switch 38.These assemblies according to first addressing circuit 6 in same way as interconnection, be described no longer in detail.
Particularly, the current modulator 34 of second addressing circuit 12 links to each other with the negative electrode of optical transmitting set 4 at node 32 places.The drain electrode of switch 38 is connected to the identical addressing electrode 20 that is connected to switch 18, and its grid and second selects electrode 26 to link to each other.
Control system 11 sends Digital Image Data and the data relevant with bias voltage to driver element 22, and periodically selects signal with preset frequency to driver element 28 transmissions.
Addressing driver element 22 sends the addressing voltage V of presentation video data by electrode 20 all optical transmitting sets in row
DAddressing driver element 22 also applies to electrode 20 and is known as bias voltage V
p, the voltage that has opposite polarity with respect to the polarity of addressing voltage.This voltage is the predefine negative voltage with predetermined lasting time.Preferably, bias voltage V
pBe between-2 volts to-25 volts.Usually, oppositely or negative bias voltage be meant between the grid of modulator and the source electrode electric potential difference V less than 0 volt
Gs: V
Gs<0V.
Capable at optical transmitting set, driver element 28 will periodically be selected voltage V
S1, V
S2Be applied to the grid of the switch 18 of first addressing circuit 6, or at the same delegation of optical transmitting set, be applied to the grid of the switch 38 of second addressing circuit 12, so that can apply addressing voltage V to the grid of the modulator 14 of first addressing circuit 6 or to the grid of the modulator 34 of second addressing circuit 12
DOr bias voltage V
p
Fig. 2 A illustrates addressing method according to the display screen of first embodiment of the invention to 2F.
This method comprises the offset programming steps A at the modulator 34 of second addressing circuit 12.Select driver element 28 to send and select voltage V to second electrode 26
S2, shown in Fig. 2 B.By selecting voltage V
S2The grid that is applied to selector switch 38 comes conducting selector switch 38.
Simultaneously, addressing driver element 22 is with the bias voltage V of negative polarity
p(V
Gs<0) is applied to addressing electrode 20.Apply bias voltage V at the grid place of current modulator 34 and the terminal place of holding capacitor 36
pShown in the curve among Fig. 2 E, during former frame, flow through modulator 34 with drain current I to optical transmitting set 4 power supplies
D2Trend towards 0 in this new image duration.
Simultaneously, shown in Fig. 2 D, with bias voltage V
pThe voltage V that polarization has stored during former frame to be applied in advance
DHolding capacitor 36; Shown in the curve among this figure, during the biasing stage at second addressing circuit 12, holding capacitor 36 keeps this bias voltage at the grid place of modulator 34, till the next programming step at modulator 34 finishes.Step B, C and D have formed the stage of second addressing circuit 12 that is used to setover jointly.
The activation threshold value voltage of modulator 34 has experienced skew in previous image image duration owing to apply addressing voltage, in this biasing stage and whole new image duration, owing to apply bias voltage V
p, skew once more, but opposite with a preceding offset direction.
The bias voltage that apply at the grid place of modulator 34 new image duration has its activation threshold value variation of counter-rotating and activation threshold value voltage is reverted to the effect of initial value, that is, return to during the former frame owing to apply the numerical value of addressing voltage before being offset at its grid place.
During addressing programming step B, select driver element 28 to produce and select voltage V at the modulator 14 of first addressing circuit 6
S1, and it is applied to first electrode 24.
Simultaneously, addressing driver element 22 is with the addressing voltage V of presentation video data
DaSend to addressing electrode 20.At the intersection point place of the addressing electrode 20 and the first selection electrode 24, selector switch 18 conductings, and with addressing voltage V
DaSend to the modulator 14 and the holding capacitor 16 of first addressing circuit 6.Because addressing voltage V
DaGreater than the activation threshold value voltage of modulator 14, between the drain electrode of modulator 14 and source electrode, produced drain current I
D1And therefore flow through optical transmitting set 4, shown in Fig. 2 F.The capacitor 16 storage representation modulators 14 addressing voltage V of grid place
DaElectromotive force so that with the duration of picture frame in the corresponding time interval in keep optical transmitting set 4 brightness.Therefore, optical transmitting set 4 is luminous during step C, till picture frame finishes.
Therefore, during step B, C and D, can see by first addressing circuit 6 providing electric current to optical transmitting set 4.Therefore, step B, C and D have formed the stage that is used to activate first addressing circuit 6 jointly.
During offset programming step D, select driver element 28 to send and select voltage V to first electrode 24 at the modulator 14 of first addressing circuit 6
S1Applying selection voltage simultaneously, addressing driver element 22 is with bias voltage V
pBe applied to electrode 20.
At the intersection point place of first electrode 24 and addressing electrode 20, selector switch 18 conductings, and send bias voltage V to modulator 14 and holding capacitor 16 at this moment
pShown in Fig. 2 D, during at the biasing stage E of first addressing circuit 6, F, holding capacitor 18 discharges are the electric charge that sent by this bias voltage of storage also.The drain current I of former frame
D1Stop to flow through modulator 14.The activation threshold value voltage of the modulator 14 that has been offset during this picture frame and has increased will reduce in new image duration (specifically during step F).
Next picture frame starts from the addressing programming step E at the modulator 34 of second addressing circuit 12.During this step, select driver element 28 will select voltage V
S2Be applied to electrode 26.Simultaneously, addressing driver element 22 is with addressing voltage V
DbBe applied to electrode 20.
Switch 38 conductings of second addressing circuit 12, and at the grid place of modulator 34 and the addressing voltage V that applies the presentation video data at the terminal place of holding capacitor 36
DbBetween the drain electrode of modulator 34 and source electrode, produce drain current I
D2This electric current has the proportional amplitude of numerical value with the view data that will send during this picture frame.During step F, this electric current flows through optical transmitting set 4, till this picture frame finishes.
Therefore, during step e and F, can see by second addressing circuit 12 providing electric current to optical transmitting set 4.Therefore, step e and F have formed the stage that is used to activate second addressing circuit 12 jointly.
As a result, the addressing of voltage, addressing voltage and bias voltage is selected in control system 11 and driver element 22 and 28 controls, so that:
-addressing voltage of positive polarity is applied to the grid of the modulator 14 of first addressing circuit 6, so that to optical transmitting set 4 power supplies, afterwards, the bias voltage of negative polarity is applied to the grid of the modulator 34 of second addressing circuit 12, so that compensate the skew of its activation threshold value voltage;
-then, according to opposite mode, the addressing voltage of positive polarity is applied to the grid of the modulator 34 of second addressing circuit 12, so that to optical transmitting set 4 power supplies, afterwards, the bias voltage of negative polarity is applied to the grid of the modulator 14 of first addressing circuit 6, so that compensate the skew of its activation threshold value voltage.
From a picture frame to another picture frame, during being used to activate the stage of first addressing circuit, provide electric current by first modulator 14 successively to optical transmitting set 4, then, during being used to activate the stage of second addressing circuit, provide electric current by second modulator 34 to optical transmitting set 4.
At each picture frame, the activation threshold value voltage of the modulator 14 of first addressing circuit and the modulator 34 of second addressing circuit increases, and reduces again then.Therefore, the advantage of this device has been to compensate the activation threshold value variation of the modulator of panel.
Fig. 3 has represented according to the optical transmitting set 4 of second embodiment of the invention and launch control unit 40 thereof.
In the present embodiment, control device 40 comprises: first addressing circuit 6 that each links to each other with optical transmitting set 4 in the array and second addressing circuit 12, at the addressing control device 42 of optical transmitting set row, at optical transmitting set capable device for selection controlling 44 and control system 56.
First addressing circuit 6 and second addressing circuit 12 comprise with reference to the identical assembly of figure 1 described addressing circuit, connect according to identical mode.According to Fig. 1 in identical label identify them, will no longer be described below.
Addressing control device 42 comprises: addressing driver element 46, first addressing electrode 48 and at second addressing electrode 50 of each row optical transmitting set.First addressing electrode 48 links to each other with the drain electrode of the switch 18 of all first addressing circuits 6 of driver element 46 and optical transmitting set row.Second addressing electrode 50 links to each other with the drain electrode of the switch 38 of all second addressing circuits 12 of driver element 46 and optical transmitting set row.
The addressing voltage V that addressing driver element 46 sends on first electrode 48
D1, and, send the addressing voltage V on second electrode 50 according to concurrent mode
D2
Device for selection controlling 44 comprises selects driver element 54 and at the single selection electrode 52 of each row optical transmitting set.Select the grid of the switch 38 of the second capable addressing circuit 12 of the grid of electrode 52 and the switch 18 of driver element 54, first addressing circuit 6 and optical transmitting set to link to each other.
Control system 56 links to each other with driver element 54 and driver element 46.This control system 56 sends Digital Image Data and the data relevant with bias voltage to driver element 46.Also send and periodically select signal to driver element 54.
Fig. 4 A illustrates display screen addressing method according to second embodiment of the invention to 4F.
The method comprising the steps of G, the addressing of capacitor 16 and the biasing of the modulator 34 of programming simultaneously are used to programme.Driver element 46 is with the addressing voltage V of presentation video data
DaSend to first electrode 48, and with bias voltage V
pSend to second electrode 50.
Simultaneously, driver element 54 sends the selection voltage V that selects on the electrode 52
S Switch 38 conductings of the switch 18 of first addressing circuit and second addressing circuit, thus bias voltage V applied at the grid place of modulator 34 and the terminal place of capacitor 36
p, and apply addressing voltage V at the grid place of modulator 14 and the terminal place of holding capacitor 16
Da
Holding capacitor 36 discharges are charged to and bias voltage V then
pThe negative potential that equates.Keep the purpose of this voltage to be by holding capacitor 36 at the grid place of modulator 34, little by little reduce the activation threshold value voltage of modulator 34, specifically during step H.Shown in the dotted line among Fig. 4 E, drain current I
D2Vanishing, and during step H, remain zero.
Capacitor 16 is charged to electromotive force V
Da, and between the drain electrode of modulator 14 and source electrode, produce drain current I
D1During step H by electric current I
D1To optical transmitting set 4 power supplies, till this picture frame finishes.
Therefore, during step G and H, provide electric current to optical transmitting set 4 by first addressing circuit 6; Therefore, step G and H have formed the stage that is used to activate first addressing circuit jointly.In addition, during step G and H, apply bias voltage at the grid of modulator 34, so that compensate the skew of its activation threshold value voltage.Therefore, step G and H have also formed the stage of second addressing circuit that is used to setover jointly.
In the addressing that is used for program storage capacitor 36 and during the step I of the biasing of the modulator 14 that is used for programming simultaneously, driver element 46 sends bias voltage V to first electrode 48
p, and send the addressing voltage V of presentation video data to second electrode 50
Db
Select voltage V by applying to electrode 52
S, open switch 18 and 38 simultaneously.Bias voltage V
pBe sent to the grid of modulator 14 and the terminal of capacitor 16.Capacitor 16 discharges, negative sense charging then.Shown in the solid line among Fig. 4 E, drain current I
D1Vanishing, and during step J, remain zero.
During step I and J, apply bias voltage V at the grid place of modulator 14
pTherefore, step I and J have formed the stage of first addressing circuit 6 that is used to setover jointly.
Simultaneously, apply addressing voltage V at the grid place of modulator 34 and at the terminal place of capacitor 36
DbThis voltage that is kept at the grid place of modulator 34 by capacitor 36 has produced the drain current I that powers to optical transmitting set 4 during step J
D2, till next programming step at new image data.
During step I and J, provide electric current to optical transmitting set 4 by second addressing circuit 12; Therefore, these steps have formed the stage that is used to activate second addressing circuit jointly.
As a result, the addressing of voltage, addressing voltage and bias voltage is selected in control system 56 and driver element 46 and 54 controls, so that:
-addressing voltage of positive polarity is applied to the grid of the modulator 14 of first addressing circuit 6, so that to optical transmitting set 4 power supplies, simultaneously the bias voltage of negative polarity is applied to the grid of the modulator 34 of second addressing circuit 12, so that compensate the skew of its activation threshold value voltage;
-then, according to opposite mode, the addressing voltage of positive polarity is applied to the grid of the modulator 34 of second addressing circuit 12, so that to optical transmitting set 4 power supplies, simultaneously, the bias voltage of negative polarity is applied to the grid of the modulator 14 of first addressing circuit 6, so that compensate the skew of its activation threshold value voltage.
Therefore, by modulator 14, be that modulator 34 provides modulating current to optical transmitting set 4 successively then.
Alternately activate first addressing circuit 6 and second addressing circuit 12, so that provide electric current to optical transmitting set 4.
When modulator 14 during, apply with the corresponding bias voltage of high negative voltage by grid and to come bias modulator 34, so that the activation threshold value voltage of the modulator 34 that is offset during the previous stage returns its initial value at modulator 34 to optical transmitting set 4 power supply.
On the contrary,, utilize this identical negative bias voltage to come bias modulator 14 when modulator 34 during to optical transmitting set 4 power supply, so as before along the activation threshold value voltage of the modulator 14 of a direction skew along opposite direction skew.Therefore, comprise that two addressing circuits that are associated with each optical transmitting set can compensate the activation threshold value variation of the modulator of display screen.
In the above-described embodiments, at each picture frame, carry out the switching of the activation of the activation of an addressing circuit and another addressing circuit according to screen of the present invention; Under the premise of not departing from the present invention, can be not at each picture frame but carry out this over-over mode between the sequence at picture frame.
In described embodiment, carry out biasing and activation stage simultaneously, and have the equal duration.As variant, control device can also be controlled modulator 14 and 34, so that have the different duration with the activation stage (although carrying out simultaneously) at the biasing of first and second circuit.
According to preferred embodiment, to one of optical transmitting set or bias voltage that another modulator applied one by one picture frame change, this change is to the function of the addressing voltage that this modulator applied during the former frame; Preferably, this bias voltage equals the described addressing voltage of former frame, but opposite in sign.