CN102376277B - Active light-sensing pixel, active light-sensing array and light-sensing method - Google Patents

Abstract

The present invention provides an active light sensing pixel, an active light sensing array and a light sensing method, wherein the active light sensing pixel comprises: a two-terminal light sensing transistor, a driving transistor and a reset capacitor. The two-terminal light sensing transistor has a first terminal coupled to a first node, a second terminal coupled to a selection signal line, and a control terminal connected to the second terminal. The driving transistor has a first terminal coupled to a first reference voltage, a second terminal coupled to an output signal line, and a control terminal connected to the first node. The reset capacitor has a first terminal connected to the control terminal of the two-terminal light sensing transistor, and a second terminal connected to the first node.

Description

Active light sensing pixel, active light sensing array and light sensing method

Technical field

The invention relates to display, particularly relevant for the display that uses active light sensing pixel, wherein active light sensing pixel is carried out simultaneously exposure and is read when selecting signal wire to be selected.

Background technology

In recent years, e-book (E-books) is gradually by development and commercialization.A kind of feasible display framework of e-book is the display framework that uses Thin Film Transistor-LCD (TFT-LCD).In other words, e-book can be by electronic package (for example TFT or optical sensor) be set in lower plate (backplane) show image.In order to mark at the display screen of e-book, e-book is necessary can sensor light.Take e-book with light sensing function as example, because optical sensor is arranged on lower plate, so penetrability is not good.Therefore, the shortcoming of the known electric philosophical works be need to be very long time shutter could mark at the display screen (display screen) of e-book.

Therefore, need a kind of active light sensing pixel badly, so that e-book can be rapidly by ground mark.

Summary of the invention

Therefore, the object of the present invention is to provide a kind of active light sensing pixel, active light sensing array and light sensing method.

In one embodiment, provide a kind of active light sensing pixel, comprising: both-end point light sensing transistor, driving transistors and replacement electric capacity.Both-end point light sensing transistor has that the first end points is coupled to first node, the second end points is coupled to the selection signal wire, and the control end points is connected in the second end points.Driving transistors has that the first end points is coupled to the first reference voltage, the second end points is coupled to output signal line, and the control end points is connected in first node.Replacement electric capacity has the first end points and is connected in the transistorized control end points of both-end point light sensing, and the second end points is connected in first node.

In another embodiment, provide a kind of active light sensing array, having comprised: a plurality of signals are selected line, a plurality of output signal line and a plurality of active light sensing pixel.Each of active light sensing pixel comprises: both-end point light sensing transistor, driving transistors and replacement electric capacity.Both-end point light sensing transistor has that the first end points is coupled to first node, the second end points is coupled to corresponding selection signal wire, and the control end points is connected in the second end points.Driving transistors has that the first end points is coupled to the first reference voltage, the second end points is coupled to corresponding output signal line, and the control end points is connected in first node.Replacement electric capacity has the first end points and is connected in the transistorized control end points of both-end point light sensing, and the second end points is connected in first node.

A kind of light sensing method also is provided in addition, is applied to active light sensing pixel, active light sensing pixel comprises: both-end point light sensing transistor, driving transistors and replacement electric capacity.Both-end point light sensing transistor has that the first end points is coupled to first node, the second end points is coupled to the selection signal wire, and the control end points is connected in the second end points.Driving transistors has that the first end points is coupled to the first reference voltage, the second end points is coupled to output signal line, and the control end points is connected in first node.Replacement electric capacity has the first end points and is connected in the transistorized control end points of both-end point light sensing, and second end points be connected in first node, the light sensing method comprises the following steps: at exposure and readout interval, provide the first voltage quasi position to selecting signal wire, so that both-end point light sensing transistor is as diode; And when both-end point light sensing transistor receives incident light, produce diode current first node is charged, so that driving transistors is according to the voltage quasi position on the first node and conducting outputs current to output signal line in order to generation.

Above-described embodiment provides active light sensing pixel and its light sensing method.Compared to known passive type light sensing pixel, the light sensing pixel of above-described embodiment has higher signal to noise ratio (S/N ratio) and driving force, therefore can satisfy the demand of large area display.In addition, the control end of above-described embodiment driving transistors is to be connected to its second end points, so display can not be activated the impact of transistor critical voltage change.The light sensing pixel of above-described embodiment and array can be arranged at the lower plate of display, and replace known Charged Coupled Device (charge coupled device, CCD) optical sensor and CMOS optical sensor.

Description of drawings

The present invention can follow appended accompanying drawing and is understood with embodiment, and appended accompanying drawing also is the part of embodiment.Known skill person should be able to know that the present patent application claim should be assert to include embodiments of the invention and modification thereof largo, wherein:

Figure 1A is the synoptic diagram of transistorized the first operator scheme of both-end point light sensing among the embodiment;

Figure 1B shows among the embodiment both-end point light sensing transistor under the first operator scheme, the voltage V of the first end points _N1With the light sensing electric current I _PhotoRelation;

Fig. 2 A is the diagram of transistorized the second operator scheme of both-end point light sensing among the embodiment;

Fig. 2 B shows both-end point light sensing transistor Q among the embodiment ₁Under the second operator scheme, double-pointed voltage V _N2Relation with diode current;

Fig. 3 is the synoptic diagram of active light sensing pixel among the embodiment;

Fig. 4 shows the sequential chart of selecting signal wire, and the voltage waveform of first node;

Fig. 5 is the synoptic diagram of the active light sensing pixel of an embodiment;

Fig. 6 is diagram and the corresponding sequential chart of signal wire of the active light sensing array of an embodiment;

Fig. 7 is diagram and the corresponding sequential chart of signal wire of the active light sensing of an embodiment and array of display.

[primary clustering symbol description]

Q ₁～both-end point light sensing transistor;

Q ₂～driving transistors;

Q ₃～switching transistor;

V _H～high voltage;

V _L～low-voltage;

Hv～incident light;

I _Photo, I ' _Photo～light sensing electric current;

I _Diode, I ' _Diode～diode current;

U ₁₁, U ₁₂, U ₁₃, U ₂₁, U ₂₂, U ₂₃, U ₃₁, U ₃₂, U ₃₃, U ₄₁, U ₄₂, U ₄₃～active light sensing and display pixel;

P ₁₁, P ₁₂, P ₁₃, P ₂₁, P ₂₂, P ₂₃, P ₃₁, P ₃₂, P ₃₃, P ₄₁, P ₄₂, P ₄₃～active light sensing pixel;

S ₂₂～display pixel;

Sel_1-Sel_4～selection signal wire;

Out_0-Out_3～output signal line;

Data_1-data_4～data signal line;

V _Ref1The～the first reference voltage;

V _Ref2The～the second reference voltage;

V _Ref3The～the three reference voltage;

X ₁～first node;

V _X1, V ' _X1, V _N1, V _N2～voltage;

V _GH～high levle driving voltage;

V _GL～low level driving voltage;

V _{Th_Q1}～critical voltage;

T ₁～the period 1;

T ₂～second round;

Creset～replacement electric capacity;

C _LC～liquid crystal capacitance;

C _Sensitivity～sensitivity adjustment electric capacity;

M _{Photo-sensing}～light sensing array;

M _{Sensing-display}～light sensing and array of display;

N ₁: the first end points;

N ₂: the second end points;

50～driving circuit;

51～sensing circuit;

52～data drive circuit.

Embodiment

Figure 1A is the synoptic diagram that the both-end point light sensing transistor among the embodiment operates in one first operator scheme (first operation mode).In the present embodiment, both-end point light sensing transistor Q ₁Be N-type hydrogenation non crystal silicon film transistor (N-type a-Si:H TFT), but be not limited to this.Both-end point light sensing transistor Q ₁Has the first end points N ₁, the second end points N ₂, and the control end points.Be noted that both-end point light sensing transistor Q ₁The control end points be to be connected to the second end points N ₂, and form whereby both-end point light sensing transistor Q ₁Two end points, i.e. the first end points N ₁Be connected in the second end points N ₂The control end points.In the first operator scheme, both-end point light sensing transistor Q ₁The first end points N ₁Be applied in high voltage V _H, and the second end points N ₂Be applied in low-voltage V _LShine the both-end point light sensing transistor Q that operates in the first operator scheme as incident light hv ₁The time, both-end point light sensing transistor Q ₁Can produce the light sensing electric current I _PhotoFlow to the second end points by the first end points.Generally speaking, light sensing electric current I _PhotoSize be by both-end point light sensing transistor Q ₁Area and the material behavior of semiconductor layer determine.In addition, light sensing electric current I _PhotoSize also can be determined by the intensity of incident light hv; In other words, if the incident light intensity is stronger, light sensing electric current I then _PhotoAlso larger.Therefore, both-end point light sensing transistor Q ₁In the first operator scheme as a photoresistance (photosensitive resistor).In another embodiment, both-end point light sensing transistor Q ₁Also can be P type silicon thin film transistor (P-type Si TFT), but be not limited to this.In other embodiments, both-end point light sensing transistor Q ₁Also can 0 be two-carrier junction transistor (BJT) or other switch module.

Figure 1B shows both-end point light sensing transistor Q ₁When operating in the first operator scheme, the voltage V of the first end points _N1With the light sensing electric current I _PhotoRelation.As shown in Figure 1B, when not having incident light hv irradiation (rhombus dotted line), the light sensing electric current I ' _PhotoIt is zero (being called again cut-off region).On the contrary, when incident light hv when irradiation (square dotted line) is arranged, with known field-effect transistor (FET) similarly, the light sensing electric current I _PhotoPlay first meeting and present linear increasing, then increasing degree diminishes (being called again triode region) gradually, and levels off at last saturated (being called again the saturation region).In one embodiment, if both-end point light sensing transistor Q ₁Shone by incident light and the voltage V of the first end points _N1Be 16V, then the light sensing electric current I _PhotoBe about the 7.5E-09 ampere; If both-end point light sensing transistor Q ₁Do not shone by incident light and the voltage V of the first end points _N1Be 16V, then the light sensing electric current I ' _PhotoIt is 0 ampere.As both-end point light sensing transistor Q ₁When operating in the first operator scheme, by detected light current sensor Iphoto, just can judge both-end point light sensing transistor Q ₁Whether shone by incident light.

Fig. 2 A is the synoptic diagram that both-end point light sensing transistor operates in one second operator scheme (second operation mode).Be similar to Figure 1A, both-end point light sensing transistor Q ₁Control end also be connected to the second end points N ₂Compared to the first operator scheme, both-end point light sensing transistor Q ₁The first end points N ₁Be applied in low-voltage V _L, and the second end points is applied in high voltage V _HBecause both-end point light sensing transistor Q ₁Control end and the second end points be coupled to high voltage V _H(being commonly referred to " diode connection "), so in the second operator scheme, both-end point light sensing transistor Q ₁As a diode, and produce diode current I _Diode(namely forward On current) is by the second end points N ₂Flow to the first end points N ₁

Fig. 2 B shows both-end point light sensing transistor Q ₁When operating in the second operator scheme, double-pointed voltage V _N2Relation with diode current.Be similar to known diode, both-end point light sensing transistor Q ₁Diode current I _DiodeOriginally be zero, then after conducting, present the increase of index pattern.At both-end point light sensing transistor Q ₁(V after the conducting _N2＞10V), no matter whether incident light hv irradiation is arranged, all exist diode current by the second end points N ₂Flow to the first end points N ₁Be noted that the diode current I of incident light hv irradiation (square dotted line) _DiodeGreater than the diode current I ' that does not have incident light hv irradiation (rhombus dotted line) _DiodeIn one embodiment, if both-end point light sensing transistor Q ₁Shone and double-pointed voltage V by incident light _N2Be 15V, then diode current I _DiodeBe about the 1.0E-09 ampere.On the contrary, if both-end point light sensing transistor Q ₁Do not shone and double-pointed voltage V by incident light _N2Be 15V, then diode current I ' _DiodeBe about the 0.5E-09 ampere.Therefore, the second operator scheme has two kinds of purposes, and the first is by the numerical value/size of detecting/judgement diode current, just can judge both-end point light sensing transistor Q ₁Whether shone by incident light.The second is to utilize diode current allow the second end points N ₂To the first end points N ₁Discharge.In general, because diode current I _DiodeNumerical value much larger than the light sensing electric current I _PhotoNumerical value (large approximately 1.0E+03～1.0E+04 the order of magnitude), so with respect in the first operator scheme, the light sensing electric current I _PhotoTo the first end points N ₁Charging process, in the second operator scheme, diode current I _DiodeTo the second end points N ₂Discharge process be faster.

Fig. 3 is the synoptic diagram of active light sensing pixel.In the present embodiment, active light sensing pixel P ₂₂Comprise both-end point light sensing transistor Q ₁, driving transistors Q ₂And replacement capacitor C _ResetActive light sensing pixel P ₂₂Be coupled to and select signal wire Sel_2, and perpendicular between the output signal line Out_2 that selects signal wire Sel_2.

In Fig. 3, both-end point light sensing transistor Q ₁Has the first end points N ₁Be coupled to first node X ₁, the second end points N ₂Be coupled to and select signal wire Sel_2, and the control end points is connected in the second end points N ₂Driving transistors Q ₂Have the first end points and be coupled to the first reference voltage V _Ref1, the second end points is coupled to output signal line Out_2, and the control end points is connected in first node X ₁The replacement capacitor C _ResetHave the first end points and be connected in both-end point light sensing transistor Q ₁The control end points, and the second end points is connected in first node X ₁

The light sensing method of light sensing pixel will be such as the explanation of following examples.Fig. 4 shows the sequential chart of selecting signal wire, and first node X ₁Voltage waveform, first node X wherein ₁Voltage waveform comprise light sensing pixel P ₂₂By incident light hv irradiation and by two kinds of situations of incident light hv irradiation.In Fig. 4, solid line represents respectively to select the sequential chart of signal wire Sel_2 and Sel_3, and dotted line represents as light sensing pixel P ₂₂When being shone by incident light hv, first node X ₁Voltage V _X1Waveform, dotted line represents as light sensing pixel P ₂₂When not shone by incident light hv, first node X ₁Voltage V ' _X1Waveform.

The transistorized operator scheme of both-end point light sensing below is discussed.At period 1 T ₁(being commonly referred to exposure and readout interval), the voltage quasi position of selection signal wire Sel_2 is pulled to and is higher than first node X ₁Voltage quasi position (such as high levle driving voltage V _GH), both-end point light sensing transistor Q ₁Produce diode current to first node X as diode and according to incident light hv ₁Charging.For example, if this moment light sensing pixel P ₂₂Shone both-end point light sensing transistor Q by incident light ₁Can produce diode current I according to incident light hv _Diode, with first node X ₁Charge to the voltage V of high levle _X1As voltage V _X1Be higher than driving transistors Q ₂Critical voltage the time, driving transistors Q ₂Be switched on and produce and output current to output signal line Out_2, so period 1 T ₁It also is readout interval.On the other hand, at period 1 T ₁If the voltage quasi position of selection signal wire Sel_2 is pulled to and is higher than first node X ₁Voltage quasi position (such as high levle driving voltage V _GH), and light sensing pixel P ₂₂When not shone by incident light, both-end point light sensing transistor Q ₁Then produce diode current I ' _DiodeWith first node X ₁Charge to the voltage V ' of high levle _X1That used here as can be known by above discussion is both-end point light sensing transistor Q ₁The second operator scheme.Be noted that as both-end point light sensing transistor Q ₁During as diode, the diode current I of incident light hv irradiation is arranged _DiodeGreater than the diode current I ' that does not have incident light hv irradiation _DiodeTherefore, with driving transistors Q ₂Critical voltage design between the diode current I that is shone by incident light hv _DiodeCorresponding voltage V _X1With the diode current I ' that is not shone by incident light hv _DiodeCorresponding voltage V ' _X1Between, so that driving transistors Q ₂Can be by diode current I _Diode(being shone by incident light) conducting, and not by diode current I ' _Diode(not shone by incident light) conducting just can be judged active light sensing pixel P ₂₂Whether shone by incident light hv.In other words, first node X ₁On voltage be V _X1The time, driving transistors Q ₂Meeting conducting, and first node X ₁On voltage be V ' _X1The time, driving transistors Q ₂Then can conducting.

At T second round ₂(usually weighing accommodation cycle) selected the voltage quasi position of signal wire Sel_2 to become and is lower than first node X ₁Voltage quasi position (such as low level driving voltage V _GL), the replacement capacitor C _ResetBy capacity coupled effect with first node X ₁Voltage V _X1Reset, so that driving transistors Q ₂Be cut off.

At T second round ₂, because driving transistors Q ₂End, so even incident light hv irradiation this moment light sensing transistor Q ₁, light sensing transistor Q ₁Can not produce diode current yet.Be noted that first node X ₁Voltage V _X1Replacement mainly be by the replacement capacitor C _ResetAnd finish.In the present embodiment, select the high levle driving voltage V of signal wire _GHBe 10V, select the low level driving voltage V of signal wire _GLBe 0V, the voltage V of the high levle on the first node and low level _X1And V ' _X1Between V _GHAnd V _GLBetween, V wherein _X1Greater than V ' _X1First node X ₁Voltage waveform V _X1Than low level driving voltage V _GLAt least high V _{Th_Q1}, V wherein _{Th_Q1}Be both-end point light sensing transistor Q ₁Critical voltage.

Fig. 5 is the synoptic diagram of active light sensing pixel.Present embodiment is similar to the embodiment of Fig. 3 substantially, and for the purpose of simplifying the description, the sequential chart of its circuit connecting mode and selection signal wire repeats no more.Be noted that active light sensing pixel P ₂₂Also comprise the sensitivity adjustment capacitor C _Sensitivity, have the first end points and be connected in first node X ₁, and the second end points is connected in the second reference voltage V _Ref2

The sensitivity adjustment capacitor C then is described _SensitivityEffect.As mentioned above, by adjusting driving transistors Q ₂Grid voltage (be first node X ₁Voltage V _X1), just can judge active light sensing pixel P ₂₂Whether shone by incident light.In the present embodiment, first node X ₁Change in voltage Δ V _X1With the change in voltage Δ V that selects signal wire Sel_2 _{Sel_2}Have following relation:

$\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="V\; X"\; filenames="HSA00000226424200021.png,HSA00000226424200051.png"\; state="\{\{state\}\}">V</figure-callout>}}_X=\frac{C_{\mathrm{sensitivity}}}{C_{\mathrm{reset}}+C_{\mathrm{sensitivity}}}\mathrm{\&Delta;}{V}_{\mathrm{Sel}\_2}$

As diode current I _Diode(Δ V when very large _X1Very large), use to have the sensitivity adjustment capacitor C of larger capacitance _SensitivityAs diode current I _Diode(Δ V when very little _X1Very little), use the sensitivity adjustment capacitor C with smaller capacitive value _SensitivityParticularly, suppose Δ V _{Sel_2}Be definite value, if demand motive transistor Q ₂Higher sensitivity (be Δ V _X1Less), then can select the less sensitivity adjustment capacitor C of capacitance _SensitivityTherefore, make diode current I even incident light is very faint _DiodeIt is very little to become, by using the less sensitivity adjustment capacitor C of capacitance _Sensitivity, still can the faint incident light hv of sensing.Whereby, to have higher signal to noise ratio (S/N ratio).

Fig. 6 is diagram and the corresponding sequential chart of signal wire of active light sensing array.Active light sensing array M _{Photo-sensing}Comprise a plurality of signals selection signal wire Sel_1-Sel_4, a plurality of output signal line Out_0-Out_3, a plurality of active light sensing pixel P ₁₁-P ₄₃, driving circuit 50, and sensing circuit 51.In the present embodiment, a plurality of active light sensing pixel P ₁₁-P ₄₃Each be similar to substantially the embodiment of Fig. 5.For the purpose of simplifying the description, the sequential chart of its circuit connecting mode and selection signal wire Sel_1-Sel_4 repeats no more.Sequentially activation of driving circuit 50 selects signal to a plurality of selection signal wire Sel_1-Sel_4.For example, at period 1 T ₁(exposure and readout interval), the voltage quasi position of selection signal wire Sel_2 is pulled to and is higher than first node X ₁Voltage quasi position (such as high levle driving voltage V _GH), both-end point light sensing transistor Q ₁As diode, and according to having or not incident light hv to produce diode current I _Diode/ I ' _Diode, with first node X ₁Charge to the voltage V of high levle _X1/ V ' _X1As first node X ₁On voltage be higher than driving transistors Q ₂Critical voltage, driving transistors Q ₂Be switched on and produce and output current to output signal line Out_2, then sensing circuit 51 is by detecting/judge that the numerical value/stool and urine of output current can determine active light sensing pixel P ₂₂Whether shone by incident light hv.Therefore, period 1 T ₁It also is readout interval.Because driving transistors Q ₂Critical voltage be the design between the diode current I that is shone by incident light hv _DiodeCorresponding voltage V _X1With the diode current I ' that is not shone by incident light _DiodeCorresponding voltage V ' _X1Between, so first node X ₁On voltage be V _X1The time, driving transistors Q ₂Meeting conducting, and first node X ₁On voltage be V ' _X1The time, driving transistors Q ₂Then can conducting.

Then, at T second round ₂, be lower than first node X when the voltage quasi position of selecting signal wire Sel_2 becomes ₁Voltage quasi position (such as low level driving voltage V _GL), driving transistors Q ₂By the replacement capacitor C _ResetVoltage V with first node _X1Reset, so that driving transistors Q ₂Be cut off.Be noted that when selecting signal wire Sel_2 be period 1 T ₁The time, selecting signal wire Sel_1, Sel_3 and Sel_4 is T second round ₂, in other words, select the corresponding scan columns of signal wire Sel_1, Sel_3 and Sel_4 to end, so select the adjacent selection signal wire Sel_1 of signal wire Sel_2 and Sel_3 can not cause interference to selecting signal wire Sel_2.In other embodiments, active light sensing array M _{Photo-sensing}Comprise selection signal wire, the scan signal line more than three more than four, and the light sensing pixel more than 12.The demand that known skill person works as according to product designs active light sensing array M _{Photo-sensing}

Fig. 7 is diagram and the corresponding sequential chart of signal wire of active light sensing and array of display.Active light sensing and array of display M _{Sensing-display}Comprise a plurality of selection signal wire Sel_1-Sel_4, a plurality of output signal line Out_0-Out_3, a plurality of data signal line data_1-data_4, a plurality of active light sensing and display pixel U ₁₁-U ₄₃, driving circuit 50, sensing circuit 51, and data drive circuit 52.In Fig. 7, active light sensing and display pixel U ₁₁-U ₄₃Each include an active light sensing pixel (P for example ₂₂) and a display pixel (S for example ₂₂), wherein each active light sensing pixel can be set up with the active light sensing pixel of previous embodiment of the present invention, does not repeat them here.With reference to display pixel S ₂₂, display pixel S ₂₂Comprise a switching transistor Q ₃An and liquid crystal capacitance C _LC, switching transistor Q wherein ₃Have one first end points and be coupled to the second data line data_2, one second end points, and a control end points is coupled to second and selects signal wire Sel_2, and liquid crystal capacitance C _LCHave one first end points and be connected in switching transistor Q ₃The second end points, and one second end points is coupled to the 3rd reference voltage V _Ref3

The operation of active light sensing and array of display below is discussed.For example, at period 1 T ₁, the voltage quasi position of selection signal wire Sel_1 is pulled to and is higher than light sensing pixel P ₂₂First node X ₁Voltage quasi position (such as high levle driving voltage V _GH), both-end point light sensing transistor Q ₁Produce diode current I as diode and according to incident light hv _Diode, and diode current I _DiodeWith first node X ₁Charge to the voltage V of high levle _X1As first node X ₁On voltage be higher than driving transistors Q ₂Critical voltage, driving transistors Q ₂Be switched on and produce and output current to output signal line Out_2, then sensing circuit 51 is by detecting/judge that the numerical value/stool and urine of output current can determine active light sensing pixel P ₂₂Whether shone by incident light hv.Therefore, period 1 T ₁It also is readout interval.Because driving transistors Q ₂Critical voltage system design between the diode current I that is shone by incident light hv _DiodeCorresponding voltage V ' _X1With the diode current I ' that is not shone by incident light _DiodeCorresponding voltage V ' _X1Between, so first node X ₁On voltage be V _X1The time, driving transistors Q ₂Meeting conducting, and first node X ₁On voltage be V ' _X1The time, driving transistors Q ₂Then can conducting.

Then, at T second round ₂, select the voltage quasi position of signal wire Sel_1 to become and be lower than first node X ₁Voltage quasi position (such as low level driving voltage V _GL), and by the replacement capacitor C _ResetCapacitance coupling effect with the voltage V of first node _X1Reset, so driving transistors Q ₂Can be cut off.At this moment, because select also driven circuit 50 activations of signal wire Sel_2, so display pixel S ₂₂Switching transistor Q ₄Conducting.Therefore, display pixel S ₂₂Show active light sensing and display pixel U according to the data-signal that is received by the second data signal line data_2 ₂₂Whether shone by incident light.

Above-described embodiment provides active light sensing pixel and its light sensing method.Compared to known passive type light sensing pixel, the light sensing pixel of above-described embodiment has higher signal to noise ratio (S/N ratio) and driving force, therefore can satisfy the demand of large area display.In addition, above-described embodiment driving transistors Q ₁Control end be to be connected to its second end points, so display can not be activated transistor Q ₁The impact of critical voltage change.The light sensing pixel of above-described embodiment and array can be arranged at the lower plate of display, and replace known Charged Coupled Device (charge coupled device, CCD) optical sensor and CMOS optical sensor.

Although the present invention discloses as above with preferred embodiment, is not to limit the present invention.In addition, known skill person should be able to know that the present patent application claim should be assert to include all embodiment of the present invention and modification thereof largo.

Claims (15)

1. An active light sensing pixel, characterized in that it comprises: A double-terminal photo-sensing transistor, having a first terminal coupled to a first node, a second terminal coupled to a selection signal line, and a control terminal connected to the second terminal; a drive transistor, with a first terminal coupled to a first reference voltage, a second terminal coupled to an output signal line, and a control terminal connected to the first node; and a reset capacitor having a first terminal connected to the control terminal of the two-terminal photo-sensing transistor, and a second terminal connected to the first node, wherein the reset capacitor is based on the signal of the selection signal line, Reset the above first node. 2. The active photo-sensing pixel according to claim 1, further comprising a sensitivity adjustment capacitor having a first terminal connected to the first node, and a second terminal connected to a second reference voltage. 3. The active photo-sensing pixel according to claim 1, wherein during an exposure and readout period, the voltage level on the selection signal line is pulled to be higher than the voltage level on the first node , the above-mentioned two-terminal photo-sensing transistor is used as a diode and generates a diode current according to an incident light, and the above-mentioned diode current charges the above-mentioned first node, so that the above-mentioned driving transistor is turned on and generates an output current to the above-mentioned output signal line . 4. The active photo-sensing pixel according to claim 3, wherein in a reset period following the exposure and readout period, the voltage level on the selection signal line becomes lower than the first When the voltage level on a node is at a certain level, the reset capacitor resets the first node through a capacitive coupling effect, so that the driving transistor is turned off. 5. The active light-sensing pixel according to claim 1, wherein the double-terminal light-sensing transistor is an N-type hydrogenated amorphous silicon thin film transistor. 6. An active photosensor array, characterized in that it comprises: Multiple signal selection lines; a plurality of output signal lines; and A plurality of active light-sensing pixels, each of the above-mentioned active light-sensing pixels includes: A double-terminal photo-sensing transistor, having a first terminal coupled to a first node, a second terminal coupled to a corresponding selection signal line, and a control terminal connected to the second terminal; a drive transistor, having a first terminal coupled to a first reference voltage, a second terminal coupled to a corresponding output signal line, and a control terminal connected to the first node; and a reset capacitor having a first terminal connected to the control terminal of the two-terminal photo-sensing transistor, and a second terminal connected to the first node, wherein the reset capacitor is based on the signal of the selection signal line, Reset the above first node. 7. The active photo-sensing array according to claim 6, wherein each of the active photo-sensing pixels further comprises a sensitivity adjustment capacitor having a first terminal connected to the first node, and a second terminal connected to a second reference voltage. 8. The active photo-sensing array according to claim 6, wherein during an exposure and readout period, the voltage level on the corresponding selection signal line is pulled higher than the voltage on the first node level, the above-mentioned two-terminal photo-sensing transistor acts as a diode and generates a diode current according to an incident light, and the above-mentioned diode current charges the above-mentioned first node, so that the above-mentioned driving transistor is turned on and generates an output current to the above-mentioned corresponding output signal line. 9. The active photo-sensing array according to claim 8, wherein during a reset period following the exposure and readout period, the voltage level on the corresponding selection signal line becomes lower than For the voltage level on the first node, the reset capacitor resets the first node through a capacitive coupling effect, so that the driving transistor is turned off. 10. The active photo-sensing array according to claim 6, wherein the two-terminal photo-sensing transistor is an N-type hydrogenated amorphous silicon thin film transistor. 11. A photo-sensing method, characterized in that it is applied to an active photo-sensing pixel, and the above-mentioned active photo-sensing pixel includes a double-terminal photo-sensing transistor with a first terminal coupled to a first node, a second terminal coupled to a selection signal line, and a control terminal connected to the second terminal; a drive transistor, with a first terminal coupled to a first reference voltage, a second terminal coupled to In an output signal line, and a control terminal connected to the above-mentioned first node; and a reset capacitor, with a first terminal connected to the control terminal of the above-mentioned double-terminal photo-sensing transistor, and a second terminal connected to the above-mentioned The first node, the above light sensing method includes the following steps: providing a first voltage level to the selection signal line during an exposure and readout period, so that the above-mentioned two-terminal photo-sensing transistor acts as a diode; When the above-mentioned two-terminal photo-sensing transistor receives an incident light, a diode current is generated to charge the above-mentioned first node, so that the above-mentioned driving transistor is turned on according to the voltage level on the above-mentioned first node to generate an output current to the above output signal lines; and In a reset period following the exposure and readout period, the first node is reset through the reset capacitor according to the signal of the selection signal line. 12. The light sensing method according to claim 11, further comprising providing a second voltage level to the selection signal line during the reset period, so that the reset capacitor resets the first node set, thus allowing the aforementioned drive transistor to be turned off. 13. The light sensing method according to claim 11, wherein the first voltage level is higher than the voltage level on the first node. 14. The light sensing method according to claim 12, wherein the second voltage level is lower than the voltage level on the first node. 15. The photo-sensing method according to claim 11, wherein the double-terminal photo-sensing transistor is an N-type hydrogenated amorphous silicon thin film transistor.

Images