CN102376277A - Active light sensing pixel, active light sensing array and light sensing method - Google Patents

Abstract

The 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 double-endpoint light sensing transistor, a driving transistor and a reset capacitor. The double-endpoint light sensing transistor comprises a first endpoint which is coupled with a first node, a second endpoint which is coupled with a selection signal wire and a control endpoint which is connected with the second endpoint. The driving transistor comprises a first endpoint which is coupled with first reference voltage, a second endpoint which is coupled with an output signal wire and a control endpoint which is connected with the first node. The reset capacitor comprises a first endpoint which is connected with the control endpoint of the double-endpoint light sensing transistor and a second endpoint which is connected with 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 exposure simultaneously 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 to use the display framework of Thin Film Transistor-LCD (TFT-LCD).In other words, e-book can be through electronic package (for example TFT or optical sensor) be set in lower plate (backplane) show image.In order will on the display screen of e-book, to mark, e-book is necessary can sensor light.With the e-book with light sensing function is example, because optical sensor is set at lower plate, so penetrability is not good.Therefore, the shortcoming of the known electric philosophical works be need be very long time shutter could on the display screen (display screen) of e-book, mark.

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

In another embodiment, a kind of active light sensing array is provided, has comprised: a plurality of signal selection wires, 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 first end points is coupled to first node, second end points is coupled to corresponding selection signal wire, and the control end points is connected in second end points.Driving transistors has that first end points is coupled to first reference voltage, second end points is coupled to the corresponding output signal line, and the control end points is connected in first node.Replacement electric capacity has first end points and is connected in the transistorized control end points of both-end point light sensing, and 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 first end points is coupled to first node, second end points is coupled to the selection signal wire, and the control end points is connected in second end points.Driving transistors has that first end points is coupled to first reference voltage, second end points is coupled to output signal line, and the control end points is connected in first node.Replacement electric capacity has 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 first voltage quasi position to selecting signal wire, make both-end point light sensing transistor as diode; And when both-end point light sensing transistor receives incident light, produce diode current first node is charged, make driving transistors according to the voltage quasi position on the first node and conducting outputs current to output signal line in order to generation.

The foregoing description provides active light sensing pixel and its light sensing method.Compared to known passive type light sensing pixel, the light sensing pixel of the foregoing description 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 the foregoing description driving transistors is to be connected to its second end points, so display can not be activated the influence of transistor critical voltage change.Light sensing pixel of the foregoing description 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 by being understood, appended accompanying drawing also is the part of embodiment with embodiment.Known art should be able to know that claim of the present invention should be assert to include embodiments of the invention and modification thereof, wherein largo:

Figure 1A is the synoptic diagram of transistorized 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 first operator scheme, the voltage V of first end points _N1With the light sensing electric current I _PhotoRelation;

Fig. 2 A is the diagram of transistorized 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 second operator scheme, the voltage V of second end points _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 the diagram and the corresponding sequential chart of signal wire of the active light sensing array of an embodiment;

Fig. 7 is the diagram and the corresponding sequential chart of signal wire of 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 _Ref1～the first reference voltage;

V _Ref2～the second reference voltage;

V _Ref3～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: first end points;

N ₂: 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 thereto.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 both-end point light sensing transistor Q whereby ₁Two end points, i.e. the first end points N ₁Be connected in the second end points N ₂The control end points.In 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 first operator scheme as incident light hv ₁The time, both-end point light sensing transistor Q ₁Can produce the light sensing electric current I _PhotoBy first endpoint stream to second end points.Generally speaking, light sensing electric current I _PhotoSize be by both-end point light sensing transistor Q ₁The area and the material behavior of semiconductor layer determine.In addition, light sensing electric current I _PhotoSize also can determine by the intensity of incident light hv; In other words, if the incident light intensity is strong more, light sensing electric current I then _PhotoAlso big more.Therefore, both-end point light sensing transistor Q ₁In 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 first operator scheme, the voltage V of first end points _N1With the light sensing electric current I _PhotoRelation.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 cut-off region again).On the contrary, when incident light hv shines (square dotted line), with known field-effect transistor (FET) similarly, the light sensing electric current I _PhotoPlay first meeting and present linear increasing, increasing degree diminishes (being called triode region again) gradually then, and levels off at last saturated (being called the saturation region again).In one embodiment, if both-end point light sensing transistor Q ₁By the voltage V of the incident light irradiation and 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 ₁Not by the voltage V of the incident light irradiation and 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 first operator scheme,, just can judge both-end point light sensing transistor Q through detected light current sensor Iphoto 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 first operator scheme, both-end point light sensing transistor Q ₁The first end points N ₁Be applied in low-voltage V _L, and second end points is applied in high voltage V _HBecause both-end point light sensing transistor Q ₁The control end and second end points be coupled to high voltage V _H(being commonly referred to " diode connection "), so in second operator scheme, both-end point light sensing transistor Q ₁As a diode, and produce diode current I _Diode(promptly forward conducting electric 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 second operator scheme, the voltage V of second end points _N2Relation with diode current.Be similar to known diode, both-end point light sensing transistor Q ₁Diode current I _DiodeOriginally be zero, after conducting, present the increase of index pattern then.At both-end point light sensing transistor Q ₁(V after the conducting _N2＞10V),, all exist diode current by the second end points N no matter whether incident light hv irradiation is arranged 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 ₁By the voltage V of the incident light irradiation and second end points _N2Be 15V, then diode current I _DiodeBe about the 1.0E-09 ampere.On the contrary, if both-end point light sensing transistor Q ₁Not by the voltage V of the incident light irradiation and second end points _N2Be 15V, then diode current I ' _DiodeBe about the 0.5E-09 ampere.Therefore, second operator scheme has two kinds of purposes, and first kind is the numerical value/size through detecting/judgement diode current, just can judge both-end point light sensing transistor Q ₁Whether shone by incident light.Second kind is to utilize diode current let 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 (big approximately 1.0E+03～1.0E+04 one magnitude), so with respect in first operator scheme, the light sensing electric current I _PhotoTo the first end points N ₁Charging process, in 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 first end points and be coupled to the first reference voltage V _Ref1, 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 first end points and be connected in both-end point light sensing transistor Q ₁The control end points, and second end points is connected in first node X ₁

The light sensing method of light sensing pixel will be like 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 situation of incident light hv irradiation.In Fig. 4, solid line representes to select the sequential chart of signal wire Sel_2 and Sel_3 respectively, and dotted line is represented as light sensing pixel P ₂₂When being shone by incident light hv, first node X ₁Voltage V _X1Waveform, dotted line is represented 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 (like 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, as if light sensing pixel P this moment ₂₂By incident light irradiation, both-end point light sensing transistor Q 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 ₁, be higher than first node X if select the voltage quasi position of signal wire Sel_2 to be pulled to ₁Voltage quasi position (like 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 _X1Can know that by above discussion that use is both-end point light sensing transistor Q here ₁Second 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 by the diode current I of incident light hv irradiation _DiodePairing voltage V _X1With the diode current I ' that is not shone by incident light hv _DiodePairing voltage V ' _X1Between, make driving transistors Q ₂Can be by diode current I _Diode(by the incident light irradiation) conducting, and not by diode current I ' _Diode(not by the incident light irradiation) 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(weighing the cycle of putting usually) selected the voltage quasi position of signal wire Sel_2 to become and is lower than first node X ₁Voltage quasi position (like low level driving voltage V _GL), the replacement capacitor C _ResetThrough capacity coupled effect with first node X ₁Voltage V _X1Reset, make driving transistors Q ₂Ended.

At T second round ₂, because driving transistors Q ₂End, so even this moment incident light hv irradiates 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 through the replacement capacitor C _ResetAnd accomplish.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 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, its circuit connecting mode repeats no more with the sequential chart of selecting signal wire.Be noted that active light sensing pixel P ₂₂Also comprise the sensitivity adjustment capacitor C _Sensitivity, have first end points and be connected in first node X ₁, and second end points is connected in the second reference voltage V _Ref2

The sensitivity adjustment capacitor C then is described _SensitivityEffect.As stated, through adjustment 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:

$\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="V\; X"\; filenames="HSA00000226424200061.png"\; state="\{\{state\}\}">V</figure-callout>}}_X=\frac{C_{\mathrm{sensitivity}}}{C_{\mathrm{reset}}+C_{\mathrm{sensitivity}}}\mathrm{\&Delta;}{V}_{\mathrm{Sel}\_2}$

As diode current I _Diode(Δ V when very big _X1Very big), use sensitivity adjustment capacitor C with big capacitance _SensitivityAs diode current I _Diode(Δ V when very little _X1Very little), use sensitivity adjustment capacitor C with smaller capacitive value _SensitivityParticularly, suppose Δ V _{Sel_2}Be definite value, if need driving transistors 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, through 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 the 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 the embodiment of Fig. 5 substantially.For the purpose of simplifying the description, its circuit connecting mode repeats no more with the sequential chart of selecting signal wire Sel_1-Sel_4.Driving circuit 50 activation in regular turn 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 (like 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, sensing circuit 51 can determine active light sensing pixel P through the numerical value/stool and urine of detecting/judgement output current then ₂₂Whether shone by incident light hv.Therefore, period 1 T ₁It also is readout interval.Because driving transistors Q ₂Critical voltage be design between by the diode current I of incident light hv irradiation _DiodePairing voltage V _X1With the diode current I ' that is not shone by incident light _DiodePairing 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 (like low level driving voltage V _GL), driving transistors Q ₂Through the replacement capacitor C _ResetVoltage V with first node _X1Reset, make driving transistors Q ₂Ended.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.Known art is when designing active light sensing array M according to product demand _{Photo-sensing}

Fig. 7 is the 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, repeats no more at this.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 ₃Second 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 (like 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, sensing circuit 51 can determine active light sensing pixel P through the numerical value/stool and urine of detecting/judgement output current then ₂₂Whether shone by incident light hv.Therefore, period 1 T ₁It also is readout interval.Because driving transistors Q ₂Critical voltage system design between by the diode current I of incident light hv irradiation _DiodePairing voltage V ' _X1With the diode current I ' that is not shone by incident light _DiodePairing 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 (like low level driving voltage V _GL), and through the replacement capacitor C _ResetCapacitance coupling effect with the voltage V of first node _X1Reset, so driving transistors Q ₂Can be ended.At this moment, because select signal wire Sel_2 also by driving circuit 50 activations, so display pixel S ₂₂Switching transistor Q ₄Conducting.Therefore, display pixel S ₂₂Data-signal according to being received by the second data signal line data_2 shows active light sensing and display pixel U ₂₂Whether shone by incident light.

The foregoing description provides active light sensing pixel and its light sensing method.Compared to known passive type light sensing pixel, the light sensing pixel of the foregoing description has higher signal to noise ratio (S/N ratio) and driving force, therefore can satisfy the demand of large area display.In addition, the foregoing description driving transistors Q ₁Control end be to be connected to its second end points, so display can not be activated transistor Q ₁The influence of critical voltage change.Light sensing pixel of the foregoing description 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.

Though the present invention discloses as above with preferred embodiment, be not in order to restriction the present invention.In addition, known art should be able to know that claim of the present invention should be assert to include all embodiment of the present invention and modification thereof largo.

Claims (15)

1. an active light sensing pixel is characterized in that, comprising:

A pair of end points light sensing transistor has one first end points and be coupled to a first node, one second end points and be coupled to one and select signal wire, and a control end points is connected in above-mentioned second end points;

One driving transistors has that one first end points is coupled to one first reference voltage, one second end points is coupled to an output signal line, and a control end points is connected in above-mentioned first node; And

One replacement electric capacity has one first end points and be connected in the transistorized control end points of above-mentioned both-end point light sensing, and one second end points is connected in above-mentioned first node.

2. active light sensing pixel according to claim 1 is characterized in that, also comprises a sensitivity adjustment electric capacity, have one first end points and be connected to above-mentioned first node, and one second end points is connected to one second reference voltage.

3. active light sensing pixel according to claim 1; It is characterized in that; At an exposure and a readout interval, the voltage quasi position on the above-mentioned selection signal wire is pulled to the voltage quasi position that is higher than on the above-mentioned first node, and above-mentioned both-end point light sensing transistor produces a diode current as a diode and according to an incident light; And above-mentioned diode current charges to above-mentioned first node, makes above-mentioned driving transistors be switched on and produce one and outputs current to above-mentioned output signal line.

4. active light sensing pixel according to claim 3; It is characterized in that; Be connected in a reset cycle of above-mentioned exposure and readout interval, when the voltage quasi position on the above-mentioned selection signal wire became the voltage quasi position that is lower than on the above-mentioned first node, above-mentioned replacement electric capacity passed through capacitance coupling effect; Above-mentioned first node is reset, make that above-mentioned driving transistors is ended.

5. active light sensing pixel according to claim 1 is characterized in that, above-mentioned both-end point light sensing transistor is a N type hydrogenation non crystal silicon film transistor.

6. an active light sensing array is characterized in that, comprising:

A plurality of signal selection wires;

A plurality of output signal lines; And

A plurality of active light sensing pixels, each of above-mentioned active light sensing pixel comprises:

A pair of end points light sensing transistor has one first end points and be coupled to a first node, one second end points and be coupled to one and select signal wire accordingly, and a control end points is connected in above-mentioned second end points;

One driving transistors has that one first end points is coupled to one first reference voltage, one second end points is coupled to a corresponding output signal line, and a control end points is connected in above-mentioned first node; And

One replacement electric capacity has one first end points and be connected in the transistorized control end points of above-mentioned both-end point light sensing, and one second end points is connected in above-mentioned first node.

7. active light sensing array according to claim 6; It is characterized in that; Each of above-mentioned active light sensing pixel also comprises a sensitivity adjustment electric capacity, have one first end points and be connected to above-mentioned first node, and one second end points is connected to one second reference voltage.

8. active light sensing array according to claim 6; It is characterized in that; At an exposure and a readout interval; Voltage quasi position on the above-mentioned corresponding selection signal wire is pulled to the voltage quasi position that is higher than on the above-mentioned first node; Above-mentioned both-end point light sensing transistor produces a diode current as a diode and according to an incident light, and above-mentioned diode current charges to above-mentioned first node, makes above-mentioned driving transistors be switched on and produce one and outputs current to above-mentioned corresponding output signal line.

9. active light sensing array according to claim 8; It is characterized in that; Be connected in a reset cycle of above-mentioned exposure and readout interval, the voltage quasi position on the above-mentioned corresponding selection signal wire becomes the voltage quasi position that is lower than on the above-mentioned first node, and above-mentioned replacement electric capacity passes through capacitance coupling effect; Above-mentioned first node is reset, make that above-mentioned driving transistors is ended.

10. active light sensing array according to claim 6 is characterized in that, above-mentioned both-end point light sensing transistor is a N type hydrogenation non crystal silicon film transistor.

11. light sensing method; It is characterized in that; Be applied to an active light sensing pixel; Above-mentioned active light sensing pixel comprises a pair of end points light sensing transistor, have one first end points and be coupled to a first node, one second end points and be coupled to one and select signal wire, and a control end points is connected in above-mentioned second end points; One driving transistors has that one first end points is coupled to one first reference voltage, one second end points is coupled to an output signal line, and a control end points is connected in above-mentioned first node; And a replacement electric capacity, have one first end points and be connected in the transistorized control end points of above-mentioned both-end point light sensing, and one second end points being connected in above-mentioned first node, above-mentioned light sensing method comprises the following steps:

At an exposure and a readout interval, one first voltage quasi position to above-mentioned selection signal wire is provided, make above-mentioned both-end point light sensing transistor as a diode; And

When above-mentioned both-end point light sensing transistor receives an incident light; Producing a diode current charges to above-mentioned first node; Make above-mentioned driving transistors according to the voltage quasi position on the above-mentioned first node and conducting outputs current to above-mentioned output signal line in order to produce one.

12. light sensing method according to claim 11; It is characterized in that; Also be included in a reset cycle that is connected in above-mentioned exposure and readout interval; One second voltage quasi position to above-mentioned selection signal wire is provided, makes above-mentioned replacement electric capacity that above-mentioned first node is reset, thereby let above-mentioned driving transistors ended.

13. light sensing method according to claim 11 is characterized in that, above-mentioned first voltage quasi position is higher than the voltage quasi position on the above-mentioned first node.

14. light sensing method according to claim 12 is characterized in that, above-mentioned second voltage quasi position is lower than the voltage quasi position on the above-mentioned first node.

15. light sensing method according to claim 11 is characterized in that, above-mentioned both-end point light sensing transistor is a N type hydrogenation non crystal silicon film transistor.

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