TWI475198B - Light sensing circuit - Google Patents

Description

Light sensing circuit

The invention relates to a light sensing circuit, in particular to a photoelectric crystal of a light sensing circuit and a control circuit thereof.

1 is a schematic diagram of a conventional light sensing circuit, wherein the light sensing circuit 100 includes a photo transistor 910, a capacitor 20, a readout transistor 30, and a read line 40. The first end of the photo-crystal 910 is electrically coupled to the capacitor 20, and the gate of the photo-crystal 910 is disposed to receive the first control signal G(n), thereby controlling the photo-crystal 910 to be turned on or off. The second end of the photo-electric crystal 910 receives the second control signal S(n), and one end of the read-out transistor 30 is electrically coupled to the capacitor 20, and the other end is electrically coupled to the read line 40.

Figure 2 is a diagram showing the operation waveform of the conventional light sensing circuit. The waveform in the figure is the voltage waveform of the terminal Va in Fig. 1, which includes the voltage waveform 60_1 under ambient light (weak light). And a voltage waveform 60_2 under the illumination of a light pen (glare). In one frame time, the operation of the light sensing circuit includes a reset period and a sensing period (sensing). In the reset period, the first control signal G(n) turns on the photo-crystal 910, and resets the voltage level of the terminal Va through the second control signal S(n).

In the sensing period, the first control signal G(n) and the second control signal S(n) are controlled to be turned off or the photo transistor 910 is operated in a state in which the conduction degree is low. However, due to the relationship of the drain current Id, the voltage level of the terminal Va is generated according to the degree to which the photo transistor 910 is exposed to light. Different sizes of leakage current Id, in turn, cause the voltage level of the terminal Va of the capacitor 20 to drop. Finally, after the end of the sensing period, the readout transistor 30 can be turned on, and the corresponding output signal Ro is supplied to the read line 40 according to the voltage level of the terminal Va. In general, the magnitude of the leakage current Id of the photo-crystal 910 is positively correlated with the degree of illumination it receives, so that at the end of the sensing period, the voltage waveform 60_1 under ambient light will be higher than the voltage waveform 60_2 under the illumination of the stylus.

In summary, through the terminal Va, different voltage characteristics are provided under different illumination levels, so that the light sensing circuit can be judged to be illuminated by the light pen based on the output signal Ro. Therefore, increasing the voltage difference between the voltage waveform 60_1 under the ambient light and the voltage waveform 60_2 under the illumination of the light pen at the end of the sensing period becomes an important issue for improving the sensitivity of the sensing.

The first technical solution of the embodiment of the present invention is a light sensing circuit, which comprises a capacitor, a double gate photoelectric crystal, a read transistor, and a control circuit. The double gate photo-electric crystal has a first end, a second end, a first gate and a second gate, and the first end of the double gate photo-electric crystal is electrically coupled to the capacitor. The read transistor is electrically coupled to the capacitor and the read line, and is configured to provide an output signal to the read line according to a voltage level stored by the capacitor. The control circuit is electrically coupled to the second gate of the dual gate photonic crystal, and is configured to control a voltage level of the second gate of the dual gate phototrans crystal according to the intensity of light irradiated to the control circuit.

A second technical solution of the embodiment of the present invention is a light sensing circuit including a capacitor, a dual gate photo transistor, a read transistor, and a control circuit. The dual gate photo transistor has a first end, a second end, a first gate and a second gate. The first end of the dual-gate photo-electric crystal is electrically coupled to the capacitor, and is disposed in response to a light intensity of the double-gate photoelectric crystal, a voltage difference between the first gate and the second end of the double-gate photoelectric crystal, and a double The second gate of the gate photodiode and the second end The voltage difference controls the leakage current flowing through the first end and the second end of the double gate phototransistor, thereby changing the potential stored in the capacitor. The readout transistor electrically couples the capacitor and the read line, and is configured to provide an output signal to the read line according to the voltage level stored by the capacitor. The control circuit is electrically coupled to the second gate of the dual gate photonic crystal, and is configured to control a voltage difference between the second gate and the second end of the dual gate phototrans crystal according to the intensity of the light irradiated to the control circuit.

A third technical solution of the embodiment of the present invention is a light sensing circuit including a capacitor, a double gate photoelectric crystal, a read transistor, and a control circuit. The dual gate photo transistor has a first end, a second end, a first gate and a second gate. The first end of the dual gate phototransistor is electrically coupled to the capacitor according to the intensity of the light irradiated to the double gate phototransistor, the voltage of the first gate of the double gate phototransistor, and the second of the double gate phototransistor The gate voltage controls the leakage current flowing through the first end and the second end of the double gate photo-electric crystal, thereby changing the voltage level of the capacitor storage. The readout transistor electrically couples the capacitor and the read line, and is configured to provide an output signal to the read line according to the voltage level stored by the capacitor. The control circuit is electrically coupled to the second gate of the double gate photoelectric crystal, and is configured to control the voltage of the second gate of the double gate photoelectric crystal according to the light intensity irradiated to the control circuit, and further, according to the light irradiated to the control circuit The intensity controls the amount of leakage current of the double gate phototransistor.

According to a specific embodiment of the first to third technical solutions of the present invention, wherein the control circuit comprises a photosensitive element, the first end of the photosensitive element is electrically coupled to the second gate of the double gate photoelectric crystal, and the photosensitive element The two ends are arranged to receive a turn-on voltage, and the photosensitive element is arranged to determine whether to provide a turn-on voltage to the second gate of the double gate transistor according to the intensity of the light irradiated to the photosensitive element.

According to a specific embodiment of the first to third technical solutions of the present invention, wherein the control circuit comprises a photosensitive element, the first end of the photosensitive element is electrically coupled to the double gate photoelectric crystal The second gate, the second end of the photosensitive element is arranged to receive a conduction voltage, and the photosensitive element is arranged to control the voltage level of the second gate of the double gate photoelectric crystal according to the intensity of the light irradiated to the photosensitive element.

According to a specific embodiment of the first to third technical solutions of the present invention, the control circuit includes a first transistor, and the first end of the first transistor is electrically coupled to the second gate of the double gate phototransistor, The second end of the first transistor is configured to receive a turn-on voltage, and the first transistor is configured to control a voltage level of the second gate of the dual gate photodiode according to the intensity of light that is incident on the first transistor.

In the above specific embodiment, the first gate of the first transistor is electrically coupled to the second gate of the dual gate photo transistor.

According to a particular embodiment of the first to third technical solutions of the present invention, the leakage current of the double gate photovoltaic crystal is positively correlated with the intensity of the light incident on the control circuit.

According to a particular embodiment of the first to third technical solutions of the present invention, wherein the voltage level of the second gate of the dual gate phototransistor is positively correlated with the intensity of the light incident on the control circuit.

According to a particular embodiment of the first to third technical solutions of the present invention, wherein the first gate of the dual gate phototransistor is configured to receive the first control signal, and the second end of the dual gate phototransistor is configured to receive The second control signal is further configured to be enabled according to the first control signal to reset the voltage level of the capacitor storage through the second control signal received by the second end of the dual gate phototransistor.

A specific embodiment of the first to third technical solutions of the present invention, wherein the gate terminal of the read transistor is configured to receive the third control signal to be based on the third control signal The readout transistor is turned on, and the output signal is supplied to the read line according to the voltage level stored in the capacitor.

The technical solution of each embodiment of the present invention transmits light according to illumination to the control circuit The second gate voltage of the double gate photo-electric crystal is controlled by the intensity, so that the leakage current of the double-gate photoelectric crystal is only slightly increased in the low-light environment, and in the environment of strong light, the double-gate photoelectric crystal is obviously The increase ultimately enables the light sensing circuits of the various embodiments of the present invention to provide output signals that differ greatly in both strong and low light environments.

10‧‧‧Photoelectric crystal

20‧‧‧ Capacitance

30‧‧‧Reading the transistor

40‧‧‧Reading line

50‧‧‧Control circuit

60_1, 60_2, 70_1, 70_2‧‧‧ voltage waveforms

100, 300, 500, 600, 800‧‧‧ optical sensing circuits

111‧‧‧Semiconductor layer

112‧‧‧ first end

113‧‧‧ second end

121‧‧‧First Gate

122‧‧‧second gate

510‧‧‧Photosensitive elements

520, 530‧‧‧Optoelectronics

531‧‧‧first gate

532‧‧‧second gate

910‧‧‧Photoelectric crystal

Dv1, dv2‧‧‧ voltage difference

Va‧‧ Endpoint

1 is a schematic diagram of a conventional light sensing circuit; FIG. 2 is a waveform diagram of a conventional light sensing circuit; FIG. 3 is a schematic view of a first embodiment of the light sensing circuit of the present invention; FIG. 5 is a schematic diagram of a second embodiment of the optical sensing circuit of the present invention; FIG. 6 is a third embodiment of the optical sensing circuit of the present invention; FIG. 7 is a schematic structural view of an embodiment of a dual gate photocrystal; FIG. 8 is a schematic view of a fourth embodiment of the photo sensing circuit of the present invention.

The terms used throughout the specification and patent application, unless otherwise noted, generally have the usual meaning of each term used in the art. The terms "substantially", "around", "about" or "approximately" as used herein shall generally mean within 20% of a given value or range, Preferably at 10% Within. In addition, the term "electrical coupling" or "electrical connection" is used herein to include both direct and indirect electrical connections. In the same way, the use of the terms "coupled" or "connected" is used in this context to include both direct and indirect connection or coupling means.

In addition, in the scope of the general specification and the patent application, if there is a description similar to "the influence of the result B according to the parameter A", the parameter A may only be a plurality of parameters affecting the result B unless otherwise specified. One or parameter A can be the only parameter that affects result B. In the context of the specification and the patent application, the use of "set to / to perform a function" to describe an element does not mean that the element has only the described function. In other words, the function may be only the element. One of several features.

The invention is described in detail below with reference to the accompanying drawings, which are not intended to limit the scope of the invention.

Figure 3 is a schematic view of a first embodiment of the light sensing circuit of the present invention. The light sensing circuit 300 includes a capacitor 20, a dual gate photo transistor 10, a readout transistor 30, and a control circuit 50. The dual gate phototransistor 10 has a first end 112, a second end 113, a first gate 121 and a second gate 122. The first end 112 of the dual gate photo-electric crystal 10 is electrically coupled to the capacitor 20, and is disposed according to the light intensity of the double-gate photo-crystal 10, the first gate 121 and the second end 113 of the double-gate photoelectric crystal. The voltage difference and the voltage difference between the second gate 122 and the second terminal 113 of the double gate phototransistor control the leakage current flowing through the first end 112 and the second end 113 of the double gate phototransistor 10, thereby changing the capacitance 20 to be stored. Voltage level.

The read transistor 30 is electrically coupled to the capacitor 20 and the read line 40, and is configured to provide an output signal Ro to the read line 40 according to the voltage level stored by the capacitor 20. The control circuit 50 is electrically coupled to the second gate 122 of the dual gate phototransistor 10, and is disposed to be based on the intensity of light that is incident on the control circuit 50. The voltage difference between the second gate 122 and the second terminal 113 of the dual gate phototransistor 10 is controlled. One end of the capacitor 20 is electrically coupled to the first end 112 of the dual gate phototransistor 10, and the other end can receive a certain voltage, for example, can be grounded.

For example, the control circuit 50 has a photosensitive element 510. One end of the photosensitive element 510 is electrically coupled to the second gate 122 of the dual gate phototransistor 10. The other end of the photosensitive element 510 is disposed to receive the turn-on voltage Von. The photosensitive member 510 is disposed to determine whether the photosensitive member 510 is turned on or off according to the intensity of light irradiated to the photosensitive member 510, or depending on the intensity of light irradiated to the photosensitive member 510, thereby determining the degree of conduction of the photosensitive member 510. More specifically, when the light intensity irradiated to the photosensitive member 510 is higher than a predetermined value, the photosensitive member 510 is turned on, and the on-voltage Von received at the other end of the photosensitive member 510 is supplied to the double gate photovoltaic crystal 10. The second gate 122, therefore, can increase the leakage current of the dual gate photo transistor 10.

In addition, the first gate 121 of the dual gate phototransistor 10 of the photo sensing circuit 300 is arranged to receive the first control signal G(n), thereby controlling the dual gate phototransistor 10 to be turned on or off. The second gate 122 of the dual gate photo transistor 10 is electrically coupled to the control circuit 50. The second terminal 113 of the dual gate photo transistor 10 receives the second control signal S(n); and the readout transistor 30 One end is electrically coupled to the capacitor 20 and the other end is electrically coupled to the read line 40.

4 is a comparison diagram of the operation waveforms of the conventional light sensing circuit and the light sensing circuit of the embodiment of the present invention. The voltage waveforms 60_1, 60_2, 70_1, and 70_2 are respectively voltage waveforms of the conventional light sensing circuit under ambient light, and the conventional light sensing circuit is The voltage waveform of the light pen illumination, the voltage waveform of the light sensing circuit of the embodiment of the present invention under ambient light, and the voltage waveform of the light sensing circuit of the embodiment of the present invention under the illumination of the light pen, and the waveforms of the above waveforms are the voltage waveform of the end point Va. .

The light sensing circuit 300 operates in a similar manner to the light sensing circuit 100, in one week. In the Frame Time, the operation of the light sensing circuit includes a reset period (rest) and a sensing period (sensing). In the reset period, the first control signal G(n) turns on the dual gate phototransistor 10, and resets the voltage level of the terminal Va through the second control signal S(n). In the sensing period, the first control signal G(n) and the second control signal S(n) are controlled to be turned off or the photo-crystal 10 is operated in a state in which the conduction degree is low. However, due to the leakage current, the voltage level of the terminal Va is different according to the degree of illumination of the double gate photo-electric crystal 10, and the voltage level of the terminal Va is lowered to generate different voltage levels. Bit. Finally, after the end of the sensing period, the readout transistor 30 can be turned on, and the corresponding output signal Ro is supplied to the read line 40 according to the voltage level of the terminal Va. In general, the magnitude of the leakage current of the photo-crystal 10 is positively correlated with the degree of illumination it receives, so that at the end of the sensing period, the voltage waveform 70_1 under ambient light will be higher than the voltage waveform 70_2 under the illumination of the stylus.

In Fig. 4, since the double gate photo-electric crystal 10 has a double gate, the control circuit 50 controls the voltage of the second gate 122 in response to the low light source under illumination of ambient light (low light source) during the sensing period. The lower the voltage level, or the second gate 122 is directly placed in the floating state, so the leakage current of the double gate photo-electric crystal 10 is only slightly larger than the leakage current of the light sensing circuit 100. Therefore, the output signal Ro provided by the light sensing circuit 300 under ambient light is only slightly lower than the output signal Ro provided by the light sensing circuit 100 under the illumination of ambient light.

However, in the case of strong light illumination (for example, light pen illumination), the control circuit 50 controls the voltage of the second gate 122 to a higher voltage level in response to a strong light source, or provides the on-voltage Von to the double gate photoelectric The second gate 122 of the crystal 10. Therefore, the leakage current of the double gate photo transistor 10 is far greater. Compared with the conventional light sensing circuit 100, in the case of strong light irradiation (for example, light pen irradiation), the leakage current of the light sensing circuit 300 is much larger than the leakage current of the light sensing circuit 100. The flow is such that the output signal Ro provided by the light sensing circuit 300 under intense light illumination (for example, light pen illumination) is much lower than that provided by the light sensing circuit 100 under illumination of strong light (for example, light pen illumination). Output signal Ro.

The voltage difference dv1 in FIG. 4 is the voltage difference of the terminal Va at the end of the sensing period of the conventional light sensing circuit 100 under the illumination of strong light (such as a light pen) and low light (such as ambient light), and the voltage difference dv2 is light. The sensing circuit 300 senses the voltage difference of the end point Va at the end of the sensing period under illumination of strong light (such as a light pen) and low light (such as ambient light). It can be clearly found that the voltage difference dv2 is greater than the voltage difference dv1, and since the output signal Ro is corresponding to the voltage of the terminal Va at the end of the sensing period, the output signal Ro provided by the light sensing circuit 300 is illuminated by strong light and low light. The difference will be greater than the conventional light sensing circuit 100. In summary, the light sensing circuit 300 is more capable of distinguishing the difference between strong light and low light illumination than the conventional light sensing circuit 100.

Figure 5 is a schematic view showing a second embodiment of the light sensing circuit of the present invention. The light sensing circuit 500 also includes a capacitor 20, a dual gate photo transistor 10, a readout transistor 30, and a control circuit 50. The double-gate photo-electric crystal 10 has a first end 112, a second end 113, a first gate 121 and a second gate 122. The first end 112 of the dual-gate photo-electric crystal 10 is electrically coupled to the capacitor 20, and is disposed. According to the light intensity irradiated to the double gate photo-electric crystal 10, the voltage difference between the first gate 121 and the second end 113 of the double gate photo-electric crystal, and the second gate 122 and the second end 113 of the double-gate photoelectric crystal The leakage current of the first terminal 112 and the second terminal 113 of the double gate phototransistor 10 is controlled by the voltage difference, thereby changing the voltage level stored by the capacitor 20.

The read transistor 30 is electrically coupled to the capacitor 20 and the read line 40, and is configured to provide an output signal Ro to the read line 40 according to the voltage level stored by the capacitor 20. The control circuit 50 is electrically coupled to the second gate 122 of the dual gate phototransistor 10, and is disposed to be based on the intensity of light that is incident on the control circuit 50. The voltage difference between the second gate 122 and the second terminal 113 of the dual gate phototransistor 10 is controlled. In addition, the operation of the light sensing circuit 500 is substantially the same as that of the light sensing circuit 300. For the waveform of the operation, please refer to FIG. 4 and FIG. 5 together, and no further details are provided herein.

The control circuit 50 of the light sensing circuit 500 includes a transistor 520. One end of the transistor 520 is electrically coupled to the second gate 122 of the dual gate photo transistor 10, The other end of the transistor 520 is disposed to receive the turn-on voltage Von. The transistor 520 is disposed to determine whether the transistor 520 is turned on or off according to the intensity of light applied to the transistor 520, or to determine the degree of conduction or leakage current of the transistor 520 according to the intensity of light applied to the transistor 520. More specifically, the higher the light intensity irradiated on the transistor 520, the larger the leakage current of the transistor 520, and the closer the voltage level of the second gate 122 of the double gate phototransistor 10 is to the turn-on voltage. Von, and the closer the second gate 122 of the double gate phototransistor 10 is to the turn-on voltage Von, the larger the leakage current of the double gate photo transistor 10.

Since the voltage level of the second gate 122 of the double gate phototransistor 10 changes with the illumination intensity, the leakage current of the double gate phototransistor 10 changes with a positive correlation as the illumination intensity is adjusted, and The change is more than the conventional light sensing circuit 100. As shown in FIG. 4, the light sensing circuit 500 is also like the light sensing circuit 300. The output signal Ro provided by the light sensing circuit 500 is greater than that of the conventional light sensing circuit 100 under the illumination of strong light and low light. In summary, the light sensing circuit 500 is more capable of distinguishing the difference between strong light and low light illumination than the conventional light sensing circuit 100.

Figure 6 is a schematic view showing a third embodiment of the light sensing circuit of the present invention. The light sensing circuit 600 also includes a capacitor 20, a dual gate photo transistor 10, a readout transistor 30, and a control circuit 50. The double-gate photo-electric crystal 10 has a first end 112, a second end 113, a first gate 121 and a second gate 122. The first end 112 of the dual-gate photo-electric crystal 10 is electrically coupled to the capacitor 20, and is disposed. According to the illumination The light intensity of the double gate phototransistor 10, the voltage difference between the first gate 121 and the second end 113 of the double gate phototransistor, and the voltage difference between the second gate 122 and the second terminal 113 of the dual gate photodiode The leakage current flowing through the first end 112 and the second end 113 of the double gate photo-electric crystal 10 is controlled to change the voltage level stored by the capacitor 20. The read transistor 30 is electrically coupled to the capacitor 20 and the read line 40 and is arranged to provide an output signal Ro to the read line 40 according to the voltage level stored by the capacitor 20.

The control circuit 50 is electrically coupled to the second gate 122 of the dual gate phototransistor 10, and is configured to control the second gate 122 and the second end 113 of the dual gate phototransistor 10 according to the intensity of the light irradiated to the control circuit 50. The voltage difference. In addition, the operation of the light sensing circuit 600 is substantially the same as that of the light sensing circuit 300 and the light sensing circuit 500. For the waveform of the operation, please refer to FIG. 4 and FIG. 6 together, and no further details are provided herein.

The control circuit 50 of the photo-sensing circuit 600 includes a transistor 530. One end of the transistor 530 is electrically coupled to the second gate 122 of the dual-gate photo-electric crystal 10, The other end of the transistor 530 is disposed to receive the turn-on voltage Von. In addition, the first gate 531 of the transistor 530 is electrically coupled to the second gate 122 of the dual gate phototransistor 10. The transistor 530 may further have a second gate 532. The second gate 532 may be grounded, for example. .

The transistor 530 is arranged to determine whether the transistor 530 is turned on or off according to the intensity of the light irradiated on the transistor 530, or depending on the intensity of the light irradiated on the transistor 530, thereby determining the degree of conduction of the transistor 530 or the magnitude of the leakage current. More specifically, the higher the light intensity irradiated on the transistor 530, the larger the leakage current of the transistor 530, and the closer the voltage level of the second gate 122 of the double gate phototransistor 10 is to the turn-on voltage. Von, the closer the second gate 122 of the double gate phototransistor 10 is to the turn-on voltage Von, the larger the leakage current of the double gate photo transistor 10.

In addition, when the voltage of the second gate 122 of the double gate phototransistor 10 is higher, As the first gate 531 of the transistor 530 is electrically coupled to the second gate 122 of the dual gate phototransistor 10, the second gate 122 of the dual gate phototransistor 10 is closer to the turn-on voltage Von. The voltage level of the first gate 531 of the transistor 530 is also closer to the turn-on voltage Von. As the voltage level of the first gate 531 of the transistor 530 approaches the on-voltage Von, the operating interval of the transistor 530 is changed, so that the leakage current of the transistor 530 is increased. In short, by electrically coupling the first gate 531 of the transistor 530 to the second gate 122 of the double gate phototransistor 10, the transistor 530 changes the forward leakage current according to the intensity of the light irradiation. This will be more pronounced than the transistor 520.

Since the voltage level of the second gate 122 of the double gate phototransistor 10 changes with the illumination intensity, the leakage current of the double gate phototransistor 10 changes with a positive correlation as the illumination intensity is adjusted, and The change is more than the conventional light sensing circuit 100. As shown in FIG. 4, the light sensing circuit 600 is also like the light sensing circuit 500. The output signal Ro provided by the light sensing circuit 600 is greater than that of the conventional light sensing circuit 100 under the illumination of strong light and low light. In summary, the light sensing circuit 500 is more capable of distinguishing the difference between strong light and low light illumination than the conventional light sensing circuit 100.

In addition, since the first gate 531 of the transistor 530 is electrically coupled to the second gate 122 of the double gate photo-electric crystal 10, the transistor 530 changes the forward leakage current according to the intensity of the light irradiation. It is more pronounced than the transistor 520. Therefore, the phenomenon that the voltage level of the second gate 122 of the double gate phototransistor 10 changes with the light intensity is more obvious than that of the light sensing circuit 500, so the light sensing circuit 600 is compared with the light sensing circuit. 500, can have a better sensing effect.

Figure 7 is a schematic view showing the structure of a double gate photovoltaic crystal embodiment. The dual gate photonic crystal 10 is suitable for the light sensing circuits 300, 500, 600, 800, but is also only a double gate photonic crystal 10 An example of implementation. Those skilled in the art will appreciate that there are other embodiments of the dual gate photovoltaic crystal 10, for example, fabricated by four reticle fabrication techniques or Advanced Hyper-Viewing Angle (AHVA). The dual gate phototransistor 10 includes a first gate (such as a gate) 121, a second gate (such as a gate) 122, a semiconductor layer 111, a first end 112, and a second end 113. The semiconductor layer 111 is sandwiched between the first gate 121 and the second gate 122. The first gate 121 and the second gate 122 can respectively control the channels formed by the semiconductor layer 111, thereby controlling the first end 112 and the second. The current path between terminals 113.

Figure 8 is a schematic view showing a fourth embodiment of the light sensing circuit of the present invention. Unlike the light sensing circuit 800 and the light sensing circuits 300, 500, 600, the second gate 122 of the dual gate photo transistor 10 directly receives the turn-on voltage Von. Therefore, the leakage current of the double gate photo-electric crystal 10 is much larger than that of the conventional photo-sensing circuit 100 regardless of whether it is illuminated by strong light or low light. Therefore, the light sensing circuits 300, 500, and 600 are compared with the light sensing circuit 800, and the output signal Ro provided by the light sensing circuits 300, 500, and 600 is greater than that of the light sensing circuit under the illumination of strong light and low light. 800.

In summary, embodiments of the present invention control the voltage of the second gate 122 of the dual gate phototransistor 10 through the control circuit 50 according to the intensity of the light that is incident on the control circuit 50, thus causing the dual gate photodiode 10 to be in a low light environment. Under the bright light environment, the double gate photo-electric crystal 10 is obviously increased, and finally the light sensing circuit of the embodiments of the present invention can be provided under the conditions of strong light and low light. Large difference output signal.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

10‧‧‧Photoelectric crystal

20‧‧‧ Capacitance

30‧‧‧Reading the transistor

40‧‧‧Reading line

50‧‧‧Control circuit

300‧‧‧Light sensing circuit

112‧‧‧ first end

113‧‧‧ second end

121‧‧‧First Gate

122‧‧‧second gate

510‧‧‧Photosensitive elements

Va‧‧ Endpoint

Claims (9)

An optical sensing circuit comprising: a capacitor; a dual gate phototransistor having a first end, a second end, a first gate and a second gate, the first of the double gate optoelectronic crystals The terminal is electrically coupled to the capacitor; a read transistor is electrically coupled to the capacitor and a read line, and is configured to provide an output signal to the read line according to the voltage level stored by the capacitor; and a control a circuit electrically coupled to the second gate, configured to control a voltage level of the second gate according to a light intensity irradiated to the control circuit; wherein the first gate of the dual gate photovoltaic crystal is configured to Receiving a first control signal, the second end of the dual gate phototransistor is configured to receive a second control signal, the dual gate photo transistor is further configured to be enabled according to the first control signal, and further The second control signal resets the voltage level stored by the capacitor. The light sensing circuit of claim 1, wherein the leakage current of the double gate photovoltaic crystal is positively correlated with the intensity of light incident on the control circuit. The optical sensing circuit of claim 2, wherein the voltage level of the second gate is positively correlated with the intensity of light incident on the control circuit. The light sensing circuit of any one of claims 1 to 3, wherein the control circuit comprises a photosensitive element, the first end of the photosensitive element being electrically coupled to the second gate, the photosensitive element The second end is configured to receive a turn-on voltage, and the photosensitive element is configured to determine whether to provide the turn-on voltage to the second gate according to the intensity of light irradiated to the photosensitive element. The optical sensing circuit according to any one of claims 1 to 3, wherein the control circuit package The first end of the photosensitive element is electrically coupled to the second gate, and the second end of the photosensitive element is disposed to receive a conduction voltage, and the photosensitive element is disposed according to the light intensity irradiated to the photosensitive element And controlling the voltage level of the second gate. The optical sensing circuit of any one of claims 1 to 3, wherein the control circuit comprises a first transistor, the first end of the first transistor is electrically coupled to the second gate, The second end of the first transistor is configured to receive a turn-on voltage, and the first transistor is configured to control a voltage level of the second gate according to a light intensity that is incident on the first transistor. The optical sensing circuit of claim 6, wherein a first gate of the first transistor is electrically coupled to the second gate. The photo sensing circuit of any one of claims 1 to 3, wherein the gate terminal of the read transistor is configured to receive a third control signal to turn on the readout according to the third control signal. The transistor further provides the output signal to the read line based on the voltage level stored by the capacitor. The optical sensing circuit of claim 1, wherein the voltage level of the second gate is positively correlated with the intensity of light incident on the control circuit.