TWI863249B - Light sensing circuit - Google Patents

Abstract

The present invention relates to a light sensing circuit, which is applied to a display panel having a plurality of pixel structures. Each of pixel structures comprises a transistor coupled to a gate line and a source line of the display panel, controlled by a gate signal of the gate line, and receiving a source signal of the source line. The light sensing circuit according to the present invention comprises a detecting circuit, which detects an electrical state of the pixel structures for sensing light.

Description

Light sensing circuit

The present invention relates to a sensing circuit, and in particular to a light sensing circuit.

Light sensing technology has been widely used in many electronic devices, especially in electronic products with display functions, such as mobile phones, tablet computers, etc. Light sensing technology is generally used to sense the intensity (brightness) of ambient light to adjust the brightness of the display panel accordingly. Most current technologies install a light sensor in electronic devices, which increases the number of components in the electronic devices. Currently, relevant industry players have proposed installing a light sensing circuit in the display panel, so that there is no need to install additional light sensors in the electronic device. However, installing a light sensing circuit in the display panel may reduce the pixel resolution of the display panel, or even the aperture ratio, which may affect the display quality.

Therefore, the present invention proposes a light sensing circuit that can utilize the pixel structure of a display panel to sense light to solve the above-mentioned problems of conventional technology.

The purpose of the present invention is to provide a light sensing circuit that detects the electrical state of the pixel structure of a display panel to sense the intensity of light, thereby avoiding the need to additionally set up a light sensing circuit on the display panel or an additional light sensor on the electronic device, thereby saving costs.

The present invention discloses a light sensing circuit, which is applied to a display panel having a plurality of pixel structures. Each pixel structure includes a transistor, which is coupled to a gate line and a source line of the display panel and is controlled by a gate signal of the gate line and receives a source signal of the source line. The light sensing circuit includes a detection circuit, which detects an electrical state of the pixel structures to sense light.

Certain terms are used in the specification and claims to refer to specific components. However, those with ordinary knowledge in the art of the present invention should understand that manufacturers may use different terms to refer to the same component. Moreover, the specification and claims do not use the difference in name as a way to distinguish components, but use the difference in the overall technology of the components as the criterion for distinction. The term "including" mentioned throughout the specification and claims is an open term and should be interpreted as "including but not limited to". Furthermore, the term "coupled" includes any direct and indirect means of connection. Therefore, if the text describes a first device coupled to a second device, it means that the first device can be directly connected to the second device, or can be indirectly connected to the second device through other devices or other means of connection.

Please refer to the first figure, which is a schematic diagram of an embodiment of the light sensing circuit of the present invention applied to a display module. As shown in the figure, the display module of the present invention includes a panel 10, a gate drive circuit 20, and a source drive circuit 30. The panel 10 includes a plurality of gate lines 11 (G0 ~ GN-1), a plurality of source lines 13 (S0 ~ SN-1) and a plurality of pixel structures 15. The gate lines 11 and the source lines 13 are interlaced with each other. The pixel structures 15 are located at the intersections. Each pixel structure 15 may include a transistor 17, a liquid crystal capacitor CL and a storage capacitor CS. The gate and source of transistor 17 are coupled to gate line 11 and source line 13 respectively, the drain of transistor 17 is coupled to a second end of liquid crystal capacitor CL and a second end of storage capacitor CS, a first end of liquid crystal capacitor CL is coupled to a common electrode COM, and a first end of storage capacitor CS is coupled to common electrode COM or a ground end. Transistor 17 can be a thin film transistor (TFT). The gate driving circuit 20 is coupled to the gate lines 11 and outputs a plurality of gate signals VG0, VG1-VGN-1 to the gate lines 11. The gate lines 11 transmit the gate signals VG0, VG1-VGN-1 to the gates of the transistors 17 of each row of the pixel structure 15 to control the transistors 17 of the pixel structures 15. The source driving circuit 30 is coupled to the source lines 13 and outputs a plurality of source signals VS0, VS1 to VSN-1 to the sources of the transistors 17 of each row of the pixel structures 15 to charge the liquid crystal capacitors CL of the pixel structures 15 to drive the pixel structures 15 to display images.

The light sensing circuit of the present invention includes a detection circuit 40, which is coupled to the source lines 13 to detect a current or a voltage of the source lines 13, and can detect the electrical state of the pixel structures 15 to generate a plurality of light detection signals, which can represent the intensity (brightness) of light. The light sensing circuit of the present invention is used in the display panel 10 in detail as follows. The light detection signals can be provided to a host, such as a microprocessor of an electronic device, so that the electronic device can know the intensity of light.

Please refer to the second figure, which is a schematic diagram of a pixel structure of the display panel of the present invention. The following description is based on the pixel structure 15 located at the intersection of the gate line G1 and the source line S1, and the other pixel structures 15 are the same. When the transistor 17 of the pixel structure 15 is controlled by the gate signal VG1 of the gate line G1 and is turned off, for example, the voltage level of the gate signal VG1 is a low voltage level, so that the voltage difference between the gate and the source of the transistor 17 is less than the threshold voltage of the transistor 17, and there is still a current _IL between the source and the drain of the transistor 17. The current _IL flows through the source and the drain of the transistor 17. The current _IL is the leakage current of the transistor 17. The magnitude of the current _IL is proportional to the intensity of the light. The higher the intensity of the light, the greater the current _IL , so the current _IL can be called a photocurrent. Therefore, the electrical characteristics of the transistor 17 of the pixel structure 15 can be used to sense the intensity of the light. Since the current _IL passes through the source of the transistor 17, it will also flow in the source line S1. In this way, the detection circuit 40 detects the current of the source line S1, which is equivalent to the detection current _IL and can generate a detection signal to sense the intensity of the light Light. In addition, since the voltage of the source line S1 is proportional to the current, the detection circuit 40 detects the voltage of the source line S1, which is equivalent to the detection current _IL and can also sense the intensity of the light Light. In addition, the detection circuit 40 can also be coupled to the transistor 17 of the pixel structure 15 to directly detect the current _IL and generate a detection signal to sense the intensity of the light Light.

Continuing from the above, the flow direction of the current _IL is determined by the voltage of the source and the voltage of the drain of the transistor 17. When the voltage of the source of the transistor 17 is greater than the voltage of the drain, the current _IL flows from the source to the drain of the transistor 17, and charges the liquid crystal capacitor CL; when the voltage of the source of the transistor 17 is less than the voltage of the drain, the current _IL flows from the drain to the source of the transistor 17, that is, the liquid crystal capacitor CL discharges, and the size of the current _IL will affect the speed of charging and discharging the liquid crystal capacitor CL. Therefore, in another embodiment of the present invention, the detection circuit 40 can be coupled to the transistor 17 and detect the storage voltage of the liquid crystal capacitor CL to generate a detection signal to sense the intensity of the light Light.

Please refer to the third figure, which is a curve diagram of the capacitance of the liquid crystal capacitor of the pixel structure of the present invention versus the storage voltage. As shown in the figure, curve CUR1 represents the relative relationship between the storage voltage of the liquid crystal capacitor CL and the relative transmittance of the light Light passing through the display panel 10. From curve CUR1, it can be seen that the storage voltage will affect the relative transmittance. The higher the storage voltage, the lower the relative transmittance, which means that the brightness of the display panel 10 is lower. Curve CUR2 is the relative relationship between the capacitance of the liquid crystal capacitor CL and the storage voltage. From curve CUR2, it can be seen that the storage voltage of the liquid crystal capacitor CL will affect the capacitance of the liquid crystal capacitor CL. When the storage voltage is approximately between 1 volt and 5 volts, the capacitance is directly proportional to the storage voltage. Based on this characteristic, in another embodiment of the present invention, the detection circuit 40 can be coupled to the transistor 17 and detect the capacitance of the liquid crystal capacitor CL to generate a detection signal to sense the intensity of the light Light. The curves CUR1 and CUR2 in the third figure are only characteristic curves of one embodiment of the display panel 10 of the present invention. Different display panels 10 will have different characteristic curves. The curves CUR1 and CUR2 in the third figure are only for illustration and are not limited to this.

Based on the characteristic that the capacitance of the liquid crystal capacitor CL changes with the storage voltage, by providing a sensing drive signal VCOM_TX (as shown in the fourth to seventh figures) to the common electrode COM (as shown in the first figure) coupled to the first end of the liquid crystal capacitor CL, it is equivalent to providing the sensing drive signal VCOM_TX to the first end of the liquid crystal capacitor CL, so that the voltage level of the second end of the liquid crystal capacitor CL will change, and its change is proportional to the capacitance of the liquid crystal capacitor CL. Therefore, the voltage level of the second end of the liquid crystal capacitor CL is related to the intensity of the light Light. In one embodiment of the present invention, the detection circuit 40 can detect the voltage level of the second end of the liquid crystal capacitor CL and generate a light detection signal to sense the intensity of the light Light. In addition, the voltage level of the drain of the transistor 17 is equal to the voltage level of the second end of the liquid crystal capacitor CL, and there is a parasitic capacitor C _SD between the source and the drain of the transistor 17, so the voltage level of the second end of the liquid crystal capacitor CL will affect the voltage level of the signal of the source line S1. The signal of the source line S1 is a source sensing signal, which is generated by corresponding to the sensing drive signal VCOM_TX. In this way, the voltage level of the source sensing signal of the source line S1 can be detected, which is equivalent to the voltage level of the second end of the liquid crystal capacitor CL, and the intensity of the light Light can be sensed. There is a parasitic capacitor C _ITO between the source of the transistor 17 and the first end of the liquid crystal capacitor CL. The parasitic capacitor C _ITO is a parasitic capacitor between the source line S1 and the conductor of the common electrode COM. Its capacitance is small, so the voltage level of the source sensing signal of the source line S1 is limited. In one embodiment of the present invention, the sensing drive signal VCOM_TX can include at least one pulse, and the level of this pulse includes a high level and a low level.

In addition, as shown in the second figure, there is a parasitic capacitor C _GD between the gate and the drain of the transistor 17, so the voltage level of the second end of the liquid crystal capacitor CL will affect the voltage level of the gate line G1. The signal of the gate line G1 is a gate sensing signal, which is generated by the corresponding sensing drive signal VCOM_TX. In this way, the voltage level of the gate sensing signal of the gate line G1 can be equivalent to the voltage level of the second end of the liquid crystal capacitor, and the intensity of the light Light can be sensed. There is a parasitic capacitor C _ITO between the gate of the transistor 17 and the first end of the liquid crystal capacitor CL. The parasitic capacitor C _ITO is a parasitic capacitor between the gate line G1 and the wire of the common electrode COM. Its capacitance is small, so the voltage level affecting the gate sensing signal of the gate line G1 is limited. The detection circuit 40 can detect the current of the source line 13, the voltage of the source line 13, the current _IL of the transistor 17, the storage voltage of the liquid crystal capacitor CL, the capacitance of the liquid crystal capacitor CL, the gate sensing signal of the gate line 11 or the source sensing signal of the source line 13, that is, detect the electrical state of the pixel structure 15 to generate a light detection signal. Since the electrical state of the pixel structure 15 changes with the intensity of the light, by detecting the electrical state of the pixel structure 15, the intensity of the light can be sensed. The following example illustrates that a sensing driving signal VCOM_TX is provided to the common electrode VOM, and the gate sensing signals of the gate lines 11 and the source sensing signals of the source lines 13 are detected to sense the intensity of the light Light.

Please refer to FIG. 4, which is a circuit diagram of the second embodiment of the light sensing circuit of the present invention. As shown in the figure, the light sensing circuit includes a sensing driving circuit 41 and a detection circuit. The sensing driving circuit 41 is coupled to the common electrode COM of the display panel 10 and generates a sensing driving signal VCOM_TX to the common electrode COM. In one embodiment of the present invention, the display panel 10 only includes a single common electrode COM, corresponding to all pixel structures 15. In one embodiment of the present invention, the sensing driving circuit 41 can be a common voltage generating circuit, which generates a sensing driving signal VCOM_TX to the common electrode COM in a light sensing cycle, and generates a display common voltage VCOM_DSP to the common electrode COM in a display cycle, so as to drive the pixel structures 15 to display images in conjunction with the source signals VS0, VS1~VSN-1.

This embodiment is described by taking 6 gate lines G0 to G5 and 8 source lines S0 to S7 as an example, but is not limited thereto. The detection circuit includes a plurality of receiving circuits 43 and a plurality of disabling circuits 45, and the receiving circuits 43 and the disabling circuits 45 are respectively coupled to the gate lines G0 to G5 and the source lines S0 to S7. In one embodiment of the present invention, each gate line G0 to G5 and each source line S0 to S7 are respectively coupled to a receiving circuit 43 and a disabling circuit 45, that is, the detection circuit couples the gate lines G0 to G5 and the source lines S0 to S7. The receiving circuits 43 coupled to the gate lines G0 to G5 receive gate sensing signals via the gate lines G0 to G5, and the receiving circuits 43 coupled to the source lines S0 to S7 receive source sensing signals via the source lines S0 to S7.

Referring again to FIG. 4 , the disabling circuits 45 are used to disable the gate lines G0 to G5 and the source lines S0 to S7, driving at least one gate line G0 to G5 or/and at least one source line S0 to S7 to a disabling state without a gate sensing signal or/and a source sensing signal. In one embodiment of the present invention, the disabling circuit 45 provides a DC level to at least one gate line G0 to G5 or/and at least one source line S0 to S7, the DC level including a ground level, and driving the gate lines G0 to G5/source lines S0 to S7 without generating a gate sensing signal/source sensing signal. In addition, the disabling circuit 45 can drive the impedance of at least one gate line G0 ~ G5 or/and at least one source line S0 ~ S7 to be high impedance and in a floating state, so that the gate lines G0 ~ G5/source lines S0 ~ S7 will not generate gate sensing signals/source sensing signals. In one embodiment of the present invention, the disabling circuits 45 can also be integrated into a single disabling circuit, and can selectively disable at least one gate line G0 ~ G5 or/and at least one source line S0 ~ S7 from generating sensing signals. The detection circuit of the present invention can further include a control circuit 47, which couples the receiving circuits 43 and the disabling circuits 45 to control the operation of the receiving circuits 43 and the disabling circuits 45. In addition, a determination circuit 49 may be included, which is coupled to the receiving circuits 43 and receives the gate sensing signals and the source sensing signals, and generates a light detection signal according to the gate sensing signals and the source sensing signals to sense the intensity of the light. The sensing drive circuit 41, the determination circuit 49 and the detection circuit may be integrated into the same chip, but is not limited thereto. For example, the determination circuit 49 may be located in a host, such as a microprocessor of an electronic device.

Please refer to FIG. 5, which is a circuit diagram of the third embodiment of the light sensing circuit of the present invention. As shown in the figure, the difference between this embodiment and the embodiment of FIG. 4 is that the gate lines G0 to G5 are grouped into a plurality of gate line groups, which include a first gate line group and a second gate line group. The first gate line group includes gate lines G0 to G2, and the second gate line group includes gate lines G3 to G5. This embodiment uses three gate lines as one gate line group but is not limited thereto. In addition, the source lines S0 to S7 are grouped into a plurality of source line groups, including the first, second, third, and fourth source line groups. The first source line group includes source lines S0 to S1, the second source line group includes source lines S2 to S3, the third source line group includes source lines S4 to S5, and the fourth source line group includes source lines S6 to S7. In this embodiment, two source lines are used as a source line group but the present invention is not limited thereto. Each gate line group and each source line group are respectively coupled to a receiving circuit 43 and a disabling circuit 45, so that the number of receiving circuits 43 and disabling circuits 45 can be reduced, and the coupling area with the common electrode COM can be increased, thereby improving the strength of the sensing signal. In the embodiment of FIG. 4 , one gate line is used as a gate line group, and one source line is used as a source line group.

The fifth embodiment is used below to illustrate the detection method of the light sensing circuit. First, the sensing driving circuit 41 provides the sensing driving signal VCOM_TX to the common electrode COM. The control circuit 47 controls the receiving circuit 43 coupled to the first source line group (source lines S0 ~ S1) to receive the first source sensing signal through the first source line group and transmit the first source sensing signal to the judgment circuit 49. At the same time, the control circuit 47 controls the disable circuit 45 coupled to the second (source lines S2 ~ S3), the third (source lines S4 ~ S5), and the fourth (source lines S6 ~ S7) source line group to drive the second, third, and fourth source line groups to be in a disabled state. The control circuit 47 also controls the first (gate line G0 ~ S1) coupled to the gate line G0 ~ S1. The first and second gate line groups are in a disabled state by the disable circuit 45 of the second (gate line G2) and the second (gate line G3 ~ G5) gate line group; then, the sense drive circuit 41 provides the sense drive signal VCOM_TX to the common electrode COM, and the control circuit 47 controls the receiving circuit 43 coupled to the second source line group to receive the second source sensing signal through the second source line group, and transmits the second source sensing signal to the judgment circuit 49, and When the control circuit 47 controls the disable circuit 45 coupled to the first, third, and fourth source line groups to drive the first, third, and fourth source line groups to a disable state, while the first and second gate line groups remain in a disable state; then, the sensing drive circuit 41 provides a sensing drive signal VCOM_TX to the common electrode COM, and the control circuit 47 controls the receiving circuit 43 coupled to the third source line group to receive the sensing drive signal VCOM_TX via the sensing drive circuit 41. The third source line group receives the third source sensing signal and transmits it to the determination circuit 49. At the same time, the control circuit 47 controls the disable circuit 45 coupled to the first, second, and fourth source line groups to drive the first, second, and fourth source line groups to a disabled state, while the first and second gate line groups remain in a disabled state. Subsequently, the sensing drive circuit 41 provides a sensing drive signal VCOM_TX to the common circuit. The control circuit 47 controls the receiving circuit 43 coupled to the fourth source line group to receive the fourth source sensing signal through the fourth source line group and transmit it to the judgment circuit 49. At the same time, the control circuit 47 controls the disabling circuit 45 coupled to the first, second and third source line groups to drive the first, second and third source line groups to be in a disabled state, while the first and second gate line groups remain in a disabled state. In this way, the judgment circuit 49 can detect the intensity of the light Light irradiated on the source line group and locate the intensity of the light Light of the first directional dimension.

Next, the sensing drive circuit 41 provides the sensing drive signal VCOM_TX to the common electrode COM, and the control circuit 47 controls the receiving circuit 43 coupled to the first gate line group to receive the first gate sensing signal through the first gate line group and transmit it to the judgment circuit 49. At the same time, the control circuit 47 controls the disable circuit 45 coupled to the second gate line group to drive the second gate line group to a disabled state. The control circuit 47 also controls the disable circuit 45 coupled to the first to fourth source line groups to drive the first To the fourth source line group is in a disabled state; thereafter, the sensing drive circuit 41 provides a sensing drive signal VCOM_TX to the common electrode COM, and the control circuit 47 controls the receiving circuit 43 coupled to the second gate line group to receive the second gate sensing signal through the second gate line group and transmit it to the judgment circuit 49. At the same time, the control circuit 47 controls the disabling circuit 45 coupled to the first gate line group to drive the first gate line group to a disabled state, and the first to fourth source line groups remain in a disabled state. In this way, the judgment circuit 49 can detect the intensity of the light Light irradiated on the gate line group and locate the intensity of the light Light of the second directional dimension. In one embodiment, multiple source sensing signals may be received through multiple source line groups at the same time or multiple gate sensing signals may be received through multiple gate line groups at the same time.

In addition, if it is necessary to accurately locate the position of the light with stronger or weaker intensity, the following steps can be further performed according to the source line group and gate line group irradiated by the light with stronger or weaker intensity as determined above. Assume that the intensity of the light irradiated on the first source line group, the third source line group, the first gate line group, and the second gate line group is weaker. The sensing drive circuit 41 provides a sensing drive signal VCOM_TX to the common electrode COM. The control circuit 47 controls the receiving circuit 43 coupled to the first source line group to receive the first source sensing signal through the first source line group and transmit it to the determination circuit 49. At the same time, the control circuit 47 also controls the receiving circuit 43 coupled to the first gate line group to receive the first gate sensing signal through the first gate line group. The sensing signal is transmitted to the judgment circuit 49, and the remaining source line groups and the remaining gate line groups are in a disabled state. If the judgment circuit 49 judges that the voltage level of the first source sensing signal and the voltage level of the first gate sensing signal are relative to the light of weaker intensity Light, it means that the intersection area of the first source line group and the first gate line group is the real irradiation area of the light of weaker intensity Light. Afterwards, the control circuit 47 controls the receiving circuit 43 coupled to the first source line group to receive the first source sensing signal through the first source line group, and at the same time, the control circuit 47 also controls the receiving circuit 43 coupled to the second gate line group to receive the second gate sensing signal through the second gate line group, and the remaining source line groups and the remaining gate line groups are all in a disabled state; then, the control circuit 47 controls the receiving circuit 43 coupled to the third source line group to receive the third source sensing signal through the third source line group, and at the same time, the control circuit 47 also controls The receiving circuit 43 coupled to the first gate line group receives the first gate sensing signal through the first gate line group, and the remaining source line groups and the remaining gate line groups are all in a disabled state; finally, the control circuit 47 controls the receiving circuit 43 coupled to the third source line group to receive the third source sensing signal through the third source line group, and the control circuit 47 also controls the receiving circuit 43 coupled to the second gate line group to receive the second gate sensing signal through the second gate line group, and the remaining source line groups and the remaining gate line groups are all in a disabled state. In this way, the judgment circuit 49 can judge all the real irradiation areas of the weaker light Light.

The fifth embodiment is used below to illustrate another detection method of the light sensing circuit. The sensing drive circuit 41 provides the sensing drive signal VCOM_TX to the common electrode COM, and the control circuit 47 controls the receiving circuit 43 coupled to the first source line group to receive the first source sensing signal through the first source line group and transmit it to the judgment circuit 49. At the same time, the control circuit 47 also controls the receiving circuit 43 coupled to the first gate line group to receive the first gate sensing signal through the first gate line group and transmit it to the judgment circuit 49. The remaining source line groups and the remaining gate line groups are all in a disabled state; thereafter , the sensing drive circuit 41 provides the sensing drive signal VCOM_TX to the common electrode COM, the control circuit 47 controls the receiving circuit 43 coupled to the first source line group to receive the first source sensing signal through the first source line group and transmit it to the determination circuit 49, and the control circuit 47 also controls the receiving circuit 43 coupled to the second gate line group to receive the second gate sensing signal through the second gate line group and transmit it to the determination circuit 49, and the remaining source line groups and the remaining gate line groups are all in the disabled state; then After that, the sensing driving circuit 41 provides the sensing driving signal VCOM_TX to the common electrode COM, and the control circuit 47 controls the receiving circuit 43 coupled to the second source line group to receive the second source sensing signal through the second source line group and transmit it to the determination circuit 49. At the same time, the control circuit 47 also controls the receiving circuit 43 coupled to the first gate line group to receive the first gate sensing signal through the first gate line group and transmit it to the determination circuit 49. The remaining source line groups and the remaining gate line groups are all in a disabled state; Next, the sensing drive circuit 41 provides the sensing drive signal VCOM_TX to the common electrode COM, and the control circuit 47 controls the receiving circuit 43 coupled to the second source line group to receive the second source sensing signal through the second source line group and transmit it to the judgment circuit 49. At the same time, the control circuit 47 also controls the receiving circuit 43 coupled to the second gate line group to receive the second gate sensing signal through the second gate line group and transmit it to the judgment circuit 49. The remaining source line groups and the remaining gate line groups are all in a disabled state. Similarly, the third source sensing signal and the first gate sensing signal are received simultaneously through the third source line group and the first gate line group; then, the third source sensing signal and the second gate sensing signal are received simultaneously through the third source line group and the second gate line group; then, the fourth source sensing signal and the first gate sensing signal are received simultaneously through the fourth source line group and the first gate line group; finally, the fourth source sensing signal and the second gate sensing signal are received simultaneously through the fourth source line group and the second gate line group.

Please refer to FIG. 6, which is a circuit diagram of the fourth embodiment of the light sensing circuit of the present invention. As shown in the figure, this embodiment includes a plurality of common electrodes COM0 to COM5, which is different from the embodiment of FIG. 4 which only includes a single common electrode COM. The common electrodes COM0 to COM5 cross the source lines S0 to S7, and the sensing drive circuit 41 couples the common electrodes COM0 to COM5 to provide a sensing drive signal VCOM_TX to the common electrodes COM0 to COM5, or drive at least one common electrode COM0 to COM5 to be in a disabled state. The sensing driving circuit 41, like the disabling circuit 45, can provide a DC level to at least one common electrode COM0-COM5 or drive at least one common electrode COM0-COM5 to float, so as to drive the common electrodes COM0-COM5 to a disabled state. In addition, the gate lines G0-G5 of this embodiment are not coupled to the receiving circuit 43 and the disabling circuit 45. The number of common electrodes is determined according to the use requirements and is not limited to a specific number.

Please refer to FIG. 7, which is a circuit diagram of the fifth embodiment of the light sensing circuit of the present invention. As shown in the figure, this embodiment is different from the fifth embodiment in that this embodiment includes a plurality of common electrodes COM0 to COM5, and is different from the fifth embodiment which only includes a single common electrode COM. In addition, the gate lines G0 to G5 of this embodiment are not coupled to the receiving circuit 43 and the disabling circuit 45.

The following is another detection method of the light sensing circuit using the seventh embodiment. The sensing driving circuit 41 provides the sensing driving signal VCOM_TX to the first common electrode COM0, and drives the second to sixth common electrodes COM1 ~ COM5 to be in a disabled state. The control circuit 47 controls the receiving circuit 43 coupled to the first to fourth source line group to receive the first to fourth source sensing signals through the first to fourth source line group, and transmits them to the judgment circuit 49, so as to judge whether the actual irradiation area of the weaker or stronger light Light is the intersection area of the first common electrode COM0 and the first to fourth source line group. Next, the sensing driving circuit 41 provides the sensing driving signal VCOM_TX to the second common electrode COM1, and drives the first common electrode COM0 and the third to sixth common electrodes COM2 ~ COM5 to be in a disabled state. The control circuit 47 controls the receiving circuit 43 coupled to the first to fourth source line groups to receive the first to fourth source sensing signals through the first to fourth source line groups and transmit them to the determination circuit 49. Similarly, the sensing driving circuit 41 provides the sensing driving signal VCOM_TX to the third common electrode COM2, and drives the first to second common electrodes COM0 to COM1, and the fourth to sixth common electrodes COM3 to COM5 to be in a disabled state, and receives the first to fourth source sensing signals through the first to fourth source line groups; thereafter, the sensing driving circuit 41 provides the sensing driving signal VCOM_TX to the fourth common electrode COM3, and drives the first to third common electrodes COM0 to COM2, and the fifth to sixth common electrodes COM4 to COM5 to be in a disabled state. COM5 is in a disabled state, and receives the first to fourth source sensing signals through the first to fourth source line groups; then, the sensing driving circuit 41 provides the sensing driving signal VCOM_TX to the fifth common electrode COM4, and drives the first to fourth common electrodes COM0 ~ COM3 and the sixth common electrode COM5 to be in a disabled state, and receives the first to fourth source sensing signals through the first to fourth source line groups; finally, the sensing driving circuit 41 provides the sensing driving signal VCOM_TX to the sixth common electrode COM5, and drives the first to fifth common electrodes COM0 ~ COM4 to be in a disabled state, and receives the first to fourth source sensing signals through the first to fourth source line groups. The above sequence of providing the sensing driving signal VCOM_TX to the common electrodes COM0 to COM5 is only an embodiment of the present invention and is not limited thereto and can be determined according to requirements.

In addition, in another embodiment of the present invention, the common electrodes COM0 to COM5 can cross the gate lines, and the gate lines can be used as sensing lines, so that the above method can also be used to detect the real irradiation area of the light with weaker or stronger intensity. From the above description, it can be known that the light sensing circuit of the present invention can be applied to touch detection or fingerprint recognition in addition to sensing the intensity of ambient light.

Please refer to FIG. 8, which is a schematic diagram of the first embodiment of the light sensing circuit of the present invention for sensing the intensity of ambient light. The display panel 10 of this embodiment has three areas A1, A2, and A3. The backlight module (not shown) only provides backlight in area A3. BL in the figure represents the backlight area, so area A3 is the display area. Area A1 is a shielding area, which is not irradiated by ambient light, while areas A2 and A3 are both irradiated by ambient light. The light sensing circuit of the present invention can detect the electrical states of the pixel structures 15 located in the areas A1, A2, and A3 respectively. The electrical state of the pixel structure 15 in the area A1 can indicate that there is no ambient light and no backlight, the electrical state of the pixel structure 15 in the area A2 can indicate that there is ambient light and no backlight, and the electrical state of the pixel structure 15 in the area A3 can indicate that there is backlight and there is ambient light. In this way, by comparing the electrical state of the pixel structure 15 in the area A1 with the electrical state of the pixel structure 15 in the area A2, the intensity of the current ambient light can be known. For example, by subtracting the voltage of the source line 13 in the region A1 from the voltage of the source line 13 in the region A2, the resulting voltage difference can represent the intensity of the ambient light.

Please refer to Figure 9, which is a schematic diagram of the second embodiment of the light sensing circuit of the present invention for sensing the intensity of ambient light. The display panel 10 of this embodiment has two areas A1 and A3. The backlight module provides backlight in areas A1 and A3. BL in the figure represents the backlight area, and area A3 is the display area. Area A1 is a shielding area, which is not irradiated by ambient light, while area A3 is irradiated by ambient light. The light sensing circuit of the present invention can detect the electrical state of the pixel structure 15 located in areas A1 and A3 respectively. The electrical state of the pixel structure 15 in area A1 can indicate that there is backlight and no ambient light, and the electrical state of the pixel structure 15 in area A3 can indicate that there is backlight and ambient light. Thus, by comparing the electrical state of the pixel structure 15 in area A1 with the electrical state of the pixel structure 15 in area A3, the intensity of the current ambient light can be known. For example, by subtracting the voltage of the source line 13 in area A1 from the voltage of the source line 13 in area A3, the voltage difference obtained can represent the intensity of the ambient light.

Please refer to FIG. 10, which is a schematic diagram of the third embodiment of the light sensing circuit of the present invention for sensing the intensity of ambient light. The display panel 10 of this embodiment has an area A3, and the backlight module provides backlight in the area A3. BL in the figure represents the backlight area, and the area A3 is illuminated by the ambient light and is the display area. The light sensing circuit of the present invention can detect the electrical state of the pixel structure 15 in the area A3 in advance under known different intensities of backlight and known different intensities of ambient light.

Please refer to the lookup table shown in Table 1. Afterwards, since the intensity of the backlight is known, the light sensing circuit can obtain the intensity of the ambient light based on the electrical state of the pixel structure 15 obtained by detection and the lookup table. If the electrical state obtained by the light sensing circuit is not in the lookup table, the intensity of the ambient light can be estimated through interpolation or extrapolation. For example, if the intensity of the backlight is known to be intensity 2, and the voltage of the source line 13 obtained by the light sensing circuit is between VRX_B2_E1 and VRX_B2_E2, it can be known that the intensity of the ambient light is between intensity 1 and intensity 2. If the intensity is to be known more accurately, a more accurate intensity of the ambient light can be estimated through interpolation. The operations described in the above-mentioned embodiments of Figures 8 to 10 can be performed using the judgment circuit 49 of the above-mentioned embodiments, but are not limited thereto. Table 1:

In summary, the light sensing circuit of the present invention utilizes the existing pixel structure of the display panel to detect the electrical state of the pixel structure, that is, to sense the intensity of light. This can avoid the need to additionally set up a light sensing circuit on the display panel, and also eliminate the need to additionally set up a light sensor in the electronic device, thereby saving costs.

However, the above is only an example of the present invention and is not intended to limit the scope of the present invention. All equivalent changes and modifications based on the shape, structure, features and spirit described in the patent application scope of the present invention should be included in the patent application scope of the present invention.

10: Panel 11: Gate line 13: Source line 15: Pixel structure 17: Transistor 20: Gate drive circuit 30: Source drive circuit 40: Detection circuit 41: Sense drive circuit 43: Receiving circuit 45: Disable circuit 47: Control circuit 49: Decision circuit A1: Region A2: Region A3: Region BL: Backlight region C _GD : Parasitic capacitor C _ITO : Parasitic capacitor CL: Liquid crystal capacitor COM: Common electrode COM0: Common electrode COM1: Common electrode COM2: Common electrode COM3: Common electrode COM4: Common electrode COM5: Common electrode CS: Storage capacitor C _SD : Parasitic capacitance CUR1: Curve CUR2: Curve G0~GN-1: Gate line I _L current Light: Light S0~SN-1: Source line VCOM_TX: Sense drive signal VG0~VGN-1: Gate signal VS0~VSN-1: Source signal

Figure 1: It is a schematic diagram of an embodiment of the light sensing circuit of the present invention applied to a display module; Figure 2: It is a schematic diagram of a pixel structure of a display panel of the present invention; Figure 3: It is a curve diagram of the capacitance of the liquid crystal capacitor of the pixel structure of the present invention versus the storage voltage; Figure 4: It is a circuit diagram of the second embodiment of the light sensing circuit of the present invention; Figure 5: It is a circuit diagram of the third embodiment of the light sensing circuit of the present invention; Figure 6: It is a circuit diagram of the fourth embodiment of the light sensing circuit of the present invention; Figure 7: It is a circuit diagram of the fifth embodiment of the light sensing circuit of the present invention; Figure 8: It is a schematic diagram of the first embodiment of the light sensing circuit of the present invention sensing the intensity of ambient light; Figure 9: It is a schematic diagram of the second embodiment of the light sensing circuit of the present invention for sensing the intensity of ambient light; and Figure 10: It is a schematic diagram of the third embodiment of the light sensing circuit of the present invention for sensing the intensity of ambient light.

without

10: Panel

11: Gate line

13: Source line

15: Pixel structure

17: Transistor

20: Gate drive circuit

30: Source drive circuit

40: Detection circuit

CL: Liquid crystal capacitor

COM: common electrode

CS: Storage capacitor

G0~GN-1: Gate line

S0~SN-1: Source line

VG0~VGN-1: Gate signal

VS0~VSN-1: Source signal

Claims (3)

A light sensing circuit is used in a display panel having a plurality of pixel structures. The pixel structures include a transistor, which is coupled to a gate line and a source line of the display panel and is controlled by a gate signal of the gate line and receives a source signal of the source line. The light sensing circuit includes: A detection circuit, which detects a current of the pixel structures to sense light. A light sensing circuit is used in a display panel having a plurality of pixel structures. The pixel structures include a transistor, which is coupled to a gate line and a source line of the display panel and is controlled by a gate signal of the gate line and receives a source signal of the source line. The light sensing circuit includes: A detection circuit, which detects an electrical state of the pixel structures to sense light; Wherein, the detection circuit detects a current of the source lines to detect the electrical state of the pixel structures. A light sensing circuit is used in a display panel having a plurality of pixel structures. The pixel structures include a transistor, which is coupled to a gate line and a source line of the display panel and is controlled by a gate signal of the gate line and receives a source signal of the source line. The light sensing circuit includes: A detection circuit, which detects an electrical state of the pixel structures to sense light; Wherein, the detection circuit detects a voltage of the source lines to detect the electrical state of the pixel structures.