[0029] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.
[0030] The technical solutions involved in the present invention will be described in detail below through specific embodiments. The present invention includes but is not limited to the following embodiments.
[0031] As shown in Figure 1(a), it is a schematic structural diagram of a photosensitive device provided by an embodiment of the present invention. The photosensitive device mainly includes: a first thin film transistor 11 as a control switch, and a first thin film transistor 11 connected to and used as a control switch. The second thin film transistor 12 of the photosensitive unit; wherein, the first thin film transistor 11 and the second thin film transistor 12 are both top-gate thin film transistors; the gate G of the second thin film transistor 12 is at least partially transparent, and the transparent area of the gate corresponds to Part of the active layer 121 in the second thin film transistor 12 is used to identify the intensity of light entering the second thin film transistor 12 when the first thin film transistor 11 and the second thin film transistor 12 are simultaneously turned on.
[0032] Through this technical solution, one thin film transistor is used as the photosensitive unit, and the other thin film transistor is used as the switching element to control the photosensitive unit. Moreover, the thin film transistor as the photosensitive unit is different from the existing thin film transistor, but the gate is designed to be at least Partially transparent, so that the active layer covered by the gate can be exposed to ambient light, thereby realizing the sensitivity to light intensity. In addition, adding a thin film transistor as a control switch can effectively distinguish the output under different light irradiation The reading of the current signal at the signal end improves the sensitivity of the photosensitive device. The most important thing is that the photosensitive device realizes the sensitivity of light intensity in the top-gate thin film transistor, which effectively expands the application range of photosensitive device identification; moreover, compared with the identification of diodes, its identification efficiency and speed Relatively high.
[0033] In addition, the first thin film transistor and the second thin film transistor involved in the present invention are low temperature polysilicon thin film transistors; because low temperature polysilicon is used, its inherent fast response speed can improve the sensitivity of the photosensitive device.
[0034] It should be noted that the principle of inductive recognition of the photosensitive device in the present invention can be briefly described based on Figure 1(b). If both thin film transistors are turned on at this time, a signal is input from the input signal terminal of the second thin film transistor, and after flowing through the second thin film transistor and the first thin film transistor, the signal is output from the output signal terminal of the first thin film transistor. Taking fingerprint pressing as an example, when the photosensitive cell 12 (second thin film transistor) in the photosensitive device is pressed by the fingerprint, the light intensity received by the active layer of the photosensitive cell 12 changes (in the prior art, the top gate The active layer of the thin film transistor of the structure is blocked by the gate to ensure the effectiveness of the active layer), in turn, will change the resistance of the photosensitive unit 12, and eventually cause the control switch 11 (first thin film transistor) side The output current of the drain has a significant change, that is, there is a significant difference between the output current when it is not pressed by the fingerprint, and further, the recognition of the fingerprint at the position is realized. The fingerprint pressing here can be replaced with stylus pressing or X-ray irradiation. The present invention does not specifically limit the way of acting on the photosensitive device, as long as it can cause the light intensity received by the active layer of the photosensitive unit to change. can.
[0035] It should be noted that in the present invention, the signal line connected to the input signal end of the photosensitive device and the signal line connected to the output signal end of the photosensitive device (the signal line filled with horizontal stripes in the figures involved in the present invention) may be a data line Or other signal lines.
[0036] In the embodiment of the present invention, the input signal terminal of the photosensitive device is located on the side of the second thin film transistor, and the output signal terminal is located on the side of the first thin film transistor. Specifically: reference image 3 As shown, the source S1 of the first thin film transistor 11 is the output signal terminal of the photosensitive device, as shown in the direction of the arrow; the drain D1 of the first thin film transistor 11 is connected to the source S2 of the second thin film transistor 12 to establish a The connection state of a thin film transistor 11 and the second thin film transistor 12; the drain D1 of the second thin film transistor 12 is the input signal terminal of the photosensitive device, as shown by the arrow direction.
[0037] Optionally, the control signals applied to the gate of the first thin film transistor and the gate of the second thin film transistor of the photosensitive device in the embodiment of the present invention may be the same or different. It can be divided into the following two situations:
[0038] In case 1, the gate of the first thin film transistor and the gate of the second thin film transistor are respectively connected to different control signal lines, that is, the gate of the first thin film transistor and the gate of the second thin film transistor are respectively applied with different control signals. Specifically referring to FIG. 2(a), the gate G1 of the first thin film transistor 11 and the gate G2 of the second thin film transistor 12 are independent of each other, and are respectively connected to different control signal lines that apply different control signals: the first thin film transistor 11 The gate G1 is connected to the first control signal line L1 to which the first control signal is applied, and the gate G2 of the second thin film transistor 12 is connected to the second control signal line L2 to which the second control signal is applied.
[0039] In addition, it should be noted that in a specific application scenario that can be realized, if multiple photosensitive devices are included, the gate of the first thin film transistor in each photosensitive device can be connected to the same control signal line, for example, to the first For the control signal line L1, the gate of the second thin film transistor in each photosensitive device can be connected to another same control signal line, for example, to the second control signal line L2. Wherein, in order to avoid blocking or crossing between the gate lines and the control signal lines, the connection can be realized by setting via holes.
[0040] Through this technical solution, the gate of the first thin film transistor and the gate of the second thin film transistor are respectively connected to different control signal lines, which can realize the separate control of the two thin film transistors more flexibly. However, the two thin film transistors must The photosensitive device can only work when it is turned on at the same time, that is, to realize the identification of different light intensity.
[0041] In case 2, the gate of the first thin film transistor and the gate of the second thin film transistor are connected to the same control signal line, that is, the gate of the first thin film transistor and the gate of the second thin film transistor are applied with the same control signal. 2(b) specifically, the gate G1 of the first thin film transistor 11 and the gate G2 of the second thin film transistor 12 are connected to each other, and the same control signal line L3 is connected via one end.
[0042] Or, as shown in FIG. 2(c), the gate G1 of the first thin film transistor 11 and the gate G2 of the second thin film transistor 12 are independent of each other, and are connected to the same control signal line L3.
[0043] Through this technical solution, the gate of the first thin film transistor and the gate of the second thin film transistor are connected to the same control signal line. For the structure shown in Figure 2(b), it can only be connected to the same control signal line; The structure of 2(c) can choose to connect different signal lines or connect the same signal line. Considering that the distance between two thin film transistors is relatively short, in order to avoid the mutual interference between the signal lines caused by connecting different signal lines, you can Two mutually independent gates are connected to the same control signal line. This wiring method not only avoids interference, but also simplifies the wiring structure.
[0044] It should be noted that the present invention does not limit the specific wiring method in the photosensitive device. Because it is a top-gate structure, the source drain and the active layer can be connected through vias or other achievable methods, without affecting the film In the case of transistor performance, the photosensitive device can be wired in a more flexible way.
[0045] Optionally, in the embodiment of the present invention, the thin film transistor in the photosensitive device may be a single gate structure thin film transistor dG, as shown in FIG. 4(a), in the single gate structure thin film transistor dG, the diagonal stripe region is active The gate G is located on the active layer, and the source S and the drain D are electrically connected to the active layer through via holes, etc.; it can also be a double-gate structure thin film transistor sG, as shown in Figure 4(b) In the double-gate structure thin film transistor sG, the diagonal stripe region is the active layer, and the gate G is located on the active layer. Since the active layer has a U-shaped structure, the gate line straddling the active layer Two gates are formed with the active layer, thereby forming a double gate structure, and the source S and the drain D are electrically connected to the active layer through vias or the like.
[0046] In the embodiment of the present invention, the first thin film transistor and the second thin film transistor are both single-gate thin film transistors; as shown in FIG. 4(c), the first thin film transistor 11 and the second thin film transistor 12 are both single-gate thin film transistors. A simple schematic diagram of the transistor dG. In this structure, the gate of the second thin film transistor 12 is a transparent conductive film layer, thereby exposing the active layer in the second thin film transistor 12, so that the second thin film transistor 12 functions as a photosensitive element The function is to realize the induction of light of different strengths from the outside, and finally convert it into output current. When the first thin film transistor 11 on the control switch side is also in the on state, if the output current of the output signal terminal changes, it means X-rays or other objects act on the photosensitive unit to achieve final recognition; otherwise, it means that no X-rays or other objects act on the photosensitive unit.
[0047] As shown in Figure 4(d), it is a simple schematic diagram that the first thin film transistor 11 and the second thin film transistor 12 are both double gate structure thin film transistors sG. In this structure, the gate of the second thin film transistor 12 (two conductive The film layer) is transparent, thereby exposing the active layer in the second thin film transistor 12, so that the second thin film transistor 12 functions as a photosensitive element, and realizes the sensing of light of different intensity entering from the outside. Among them, since there are two gates in the double-gate structure, the area exposed to the active layer can be relatively large, so that the degree of changing the output current is relatively high, that is, more active layers are exposed. The layer is affected by the light, and in turn, can change the output current to a large extent.
[0048] For example: for the photosensitive device with a single gate structure shown in Figure 4(c), the output current when it is not affected is I1, and when it is affected, the output current becomes I2, and the current difference before and after the change is obtained accordingly △I; For the photosensitive device with double-gate structure shown in Figure 4(d), the output current when it is not affected is I3, and when it is affected, the output current becomes I4, and the current difference before and after the change is obtained accordingly It is △I'. And it is known that △I'> △I, then, it is obvious that the photosensitive device shown in Figure 4(d) has a strong sense of current change, so as a photosensitive device, its sensitivity is higher than that of the single-gate structure shown in Figure 4(c).
[0049] For another example, the photosensitive device involved in the present invention may also be a combination of a single-gate structure thin film transistor dG and a double-gate structure thin film transistor sG. 4(e) the first thin film transistor 11 is a single-gate structure thin film transistor dG, and the second thin film transistor 12 is a double-gate structure thin film transistor sG, or, referring to FIG. 4(f), the first thin film transistor 11 is The double-gate structure thin film transistor sG, and the second thin film transistor 12 are both single-gate structure thin film transistors dG. It should be noted that the two photosensitive devices of Figure 4(e) and Figure 4(f), no matter which structure, can achieve a good effect on different light, especially when the photosensitive unit is not affected. The recognition of the light at the time, it is better to realize the recognition of external X-ray light and fingerprint touch.
[0050] Optionally, in the embodiment of the present invention, in order to improve the sensitivity of the photosensitive device, all gates in the second thin film transistor may be set to be transparent, and the gate corresponds to all active layers in the second thin film transistor. Referring to Figure 5(a), for a thin film transistor with a single-gate structure, its gate corresponds to all the active layer (mesh area), so that the area where the light irradiates the active layer is large enough, so that the output signal end The change in current can be detected more accurately, and the sensitivity of the photosensitive device can be improved. In the same way, as shown in FIG. 5(b), in the thin film transistor of the double-gate structure, the gate connected between the two active layers corresponds to all the active layers (mesh area) covered by it.
[0051] Similarly, in the embodiment of the present invention, a photosensitive device is also provided, with reference to Image 6 As shown in the schematic structural diagram of the photosensitive device, the photosensitive device A mainly includes at least one photosensitive device B involved in any of the above embodiments.
[0052] Optionally, the photosensitive device may be a display panel A1. As shown in FIG. 7(a), a plurality of photosensitive devices B1 are arranged in the same array as the pixel unit B2 and are tiled on the display panel in a one-to-one correspondence with the pixel unit B2. In A1, or, as shown in FIG. 7(b), the photosensitive device B1 is respectively integrated in each pixel unit B2 of the display panel A1, wherein only some of the pixel units B2 are integrated with B1, and other unmarked ones are also It is integrated, but it is not identified.
[0053] For example, when a touch object (such as a finger or a stylus) touches the display panel A1, or X-ray-like light irradiates the surface of the display panel A1, the photosensitive device B1 in the display panel A1 will be affected The effect is actually that the active layer in the photosensitive device B1 is affected, thereby changing the resistance of the channel, and further, changing the output current of the output signal terminal. When the output signal terminal detects different output currents, the display can be determined This area of the panel is irradiated by touch or other light, so as to recognize fingerprints and other light stimuli.
[0054] Optionally, for the display panel shown in FIG. 7(a), the sensing layer composed of the photosensitive device B1 is tiled between any achievable film layers of the display panel A1 and does not affect the display effect, in order to ensure The signal lines will not interfere with each other and simplify the wiring complexity. The control signal in the photosensitive device B1 can be provided by an additional signal line; and for the display panel shown in Figure 7(b), each photosensitive device is separately Integrate in each pixel unit of the display panel. Similarly, in order to avoid mutual interference between signal lines and avoid complication caused by additional wiring, the control signal of the photosensitive device can be provided by the gate line that defines the pixel unit Further, in order to simplify the component composition of each pixel unit, the first thin film transistor as a control switch in the photosensitive device is also used to drive the corresponding pixel unit. Therefore, the photosensitive device and the pixel unit share a control switch, which avoids each pixel unit. There are two control switches to simplify the structure of each pixel unit to the greatest extent.
[0055] Optionally, in the embodiment of the present invention, the photosensitive device involved can also be integrated into medical equipment such as X-ray imaging, and its specific structure is not introduced here, and the principle of the photosensitive device can be combined with the specific application. The scene is designed and used flexibly.
[0056] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.
[0057] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. In this way, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.
