Microbolometer and method of thermal sensing thereof

Abstract

The present application provides a microbolometer and a thermal sensing method thereof. Each switching circuit switches the first connection point or the second connection point of the corresponding thermal sensing pixel to be connected to different signal transmission lines or a shared connection line, to adjust the connection mode of the plurality of thermal sensing pixels, and change the sensing signals provided by the plurality of thermal sensing pixels.

Description

TECHNICAL FIELD

[0001] The present invention relates to a sensing device, and more particularly to a micro-bolometer and a thermal sensing method thereof. BACKGROUND

[0002] A micro-bolometer is a temperature sensor that can measure radiant energy and convert it into an electrical signal output. Generally, the connection mode between the micro-bolometer pixels of a micro-bolometer array is fixed after the micro-bolometer array is packaged, i.e., the characteristics of the micro-bolometer array are fixed and cannot be adjusted to match the characteristics of a subsequent circuit, such as adjusting the dynamic range of the subsequent circuit to match the sensing signal provided by the micro-bolometer array, which makes the micro-bolometer less flexible in use. SUMMARY

[0003] The present invention provides a micro-bolometer and a thermal sensing method thereof, which can greatly improve the flexibility of the micro-bolometer in use.

[0004] The micro-bolometer of the present invention includes a plurality of thermal sensing pixels and a plurality of switching circuits. Each thermal sensing pixel has a first connection point and a second connection point. The plurality of switching circuits are respectively coupled to a first signal transmission line, a second signal transmission line, at least one shared connection line, and the first connection point or the second connection point of the corresponding thermal sensing pixel, to switch the first connection point or the second connection point of the corresponding thermal sensing pixel to the first signal transmission line, the second signal transmission line, or the shared connection line, to adjust the connection mode of the plurality of thermal sensing pixels and change the sensing signal provided by the plurality of thermal sensing pixels, wherein the thermal sensing pixels and the switching circuits are formed together on a silicon substrate by a semiconductor process.

[0005] In an embodiment of the present invention, the micro-bolometer further includes a sensing circuit and a signal processing circuit. The sensing circuit is coupled to the first signal transmission line and the second signal transmission line to perform signal amplification processing on the sensing signal. The signal processing circuit is coupled to the sensing circuit to perform analog-to-digital conversion processing on the sensing signal provided by the sensing circuit.

[0006] In an embodiment of the present invention, the micro-bolometer further includes a control circuit coupled to the plurality of switching circuits to control the plurality of switching circuits to adjust the connection mode of the plurality of thermal sensing pixels according to the dynamic range of the signal processing circuit.

[0007] In an embodiment of the present invention, the connection mode of the plurality of thermal sensing pixels includes at least one of series connection, parallel connection, or open connection.

[0008] In an embodiment of the present application, the thermal sensing pixel further comprises a reference pixel.

[0009] The present application also provides a thermal sensing method of a microbolometer, the microbolometer comprising a plurality of thermal sensing pixels and a plurality of switching circuits, each thermal sensing pixel having a first connection point and a second connection point, the thermal sensing method of the microbolometer comprising the following steps. The plurality of switching circuits are provided, the switching circuits connecting a first signal transmission line, a second signal transmission line, at least one shared connection line and the first connection point or the second connection point of the corresponding thermal sensing pixel. The switching circuits are controlled to switch the first connection point or the second connection point of the corresponding thermal sensing pixel to be connected to the first signal transmission line, the second signal transmission line or the shared connection line, so as to adjust the connection mode of the plurality of thermal sensing pixels and change the sensing signals provided by the plurality of thermal sensing pixels, wherein the thermal sensing pixels and the switching circuits are formed on a silicon substrate by a semiconductor process.

[0010] In an embodiment of the present application, the sensing signals generated by the plurality of thermal sensing pixels are transmitted to the signal processing circuit for analog-digital conversion processing.

[0011] In an embodiment of the present application, the thermal sensing method of the microbolometer comprises adjusting the connection mode of the plurality of thermal sensing pixels by the plurality of switching circuits according to the dynamic range of the signal processing circuit.

[0012] In an embodiment of the present application, the connection mode of the plurality of thermal sensing pixels comprises at least one of series connection, parallel connection or disconnection.

[0013] In an embodiment of the present application, the thermal sensing pixel comprises a microbolometer pixel.

[0014] In an embodiment of the present application, the thermal sensing pixel further comprises a reference pixel.

[0015] Based on the above, the microbolometer of the embodiment of the present application can adjust the connection mode of the plurality of thermal sensing pixels by switching the first connection point or the second connection point of the thermal sensing pixel corresponding to each switching circuit to be connected to different signal transmission lines or shared connection lines, so as to change the sensing signals provided by the plurality of thermal sensing pixels, avoid the situation that the connection mode of the thermal sensing pixels cannot be adjusted after the microbolometer is packaged, and greatly improve the use flexibility of the microbolometer.

[0016] In order to make the above features and advantages of the present application more obvious and easy to understand, the following specific embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a top view schematic diagram of a microbolometer according to an embodiment of the present application;

[0018] Figure 2 is a schematic diagram of a microbolometer according to an embodiment of the present application;

[0019] Figure 3 is a schematic diagram of a microbolometer according to another embodiment of the present application;

[0020] Figure 4 is a schematic diagram of a microbolometer according to another embodiment of the present application;

[0021] Figure 5 is a schematic diagram of a microbolometer according to another embodiment of the present application;

[0022] Figure 6 is a schematic diagram of a microbolometer according to another embodiment of the present application;

[0023] Figure 7 is a flowchart of a thermal sensing method of a microbolometer according to an embodiment of the present application.

[0024] BRIEF DESCRIPTION OF DRAWINGS

[0025] 102: signal processing circuit

[0026] 104: control circuit

[0027] 115: silicon substrate

[0028] 120, 130: microbolometer pixels

[0029] 140: shield

[0030] 190: signal line arrangement region

[0031] 195: input / output pad

[0032] RP: reference pixel

[0033] P1-P4: thermal sensing pixels

[0034] SW1-SW8: switching circuits

[0035] S1: sensing signal

[0036] L1, L2: signal transmission lines

[0037] N1, N2: connection points

[0038] LC1-LC4: shared connection lines

[0039] S702-S704: thermal sensing method steps of a microbolometer DETAILED DESCRIPTION

[0040] Figure 1 is a top view schematic diagram of a microbolometer according to an embodiment of the present application. The microbolometer can include a plurality of thermal sensing pixels (including microbolometer pixels 120, reference pixels RP), a plurality of signal line setting regions 190, and a plurality of input / output pads 195. The microbolometer pixels 120 and the reference pixels RP are arranged in an array on a silicon substrate 115, and the plurality of signal line setting regions 190 and the plurality of input / output pads 195 are also disposed on the silicon substrate 115. The microbolometer pixels 120 are located between the reference pixels RP

[0041] The microbolometer pixels 120 and the reference pixels RP can both serve as thermal sensing pixels. One or more signal lines (such as signal transmission lines and shared connection lines, but not limited thereto) can be disposed in the signal line setting regions 190, where the signal line setting regions 190 are disposed on opposite sides of the array formed by the microbolometer pixels 120 and the reference pixels RP, and between the input / output pads 195 and the array formed by the microbolometer pixels 120 and the reference pixels RP. The reference pixels 150 have a similar structure to the microbolometer pixels 120, and the sensing signals provided by the reference pixels 150 only reflect the characteristics of the circuit substrate, such as the material characteristics and electrical signal characteristics of the circuit substrate, and the sensing signals provided by the reference pixels 150 can be used to provide the signal processing circuit in the back end with signal processing to remove the characteristics of the circuit substrate, so as to obtain more accurate sensing results.

[0042]

[0043] The microbolometer pixels 120 and the reference pixels RP can both serve as thermal sensing pixels. One or more signal lines (such as signal transmission lines and shared connection lines, but not limited thereto) can be disposed in the signal line setting regions 190, where the signal line setting regions 190 are disposed on opposite sides of the array formed by the microbolometer pixels 120 and the reference pixels RP, and between the input / output pads 195 and the array formed by the microbolometer pixels 120 and the reference pixels RP. The reference pixels 150 have a similar structure to the microbolometer pixels 120, and the sensing signals provided by the reference pixels 150 only reflect the characteristics of the circuit substrate, such as the material characteristics and electrical signal characteristics of the circuit substrate, and the sensing signals provided by the reference pixels 150 can be used to provide the signal processing circuit in the back end with signal processing to remove the characteristics of the circuit substrate, so as to obtain more accurate sensing results.

[0044] Figure 2 is a schematic diagram of a microbolometer according to an embodiment of the present application. Further,

[0045] The microbolometer includes thermal sensing pixels P1, switching circuits SW1, SW2, a signal processing circuit 102, a control circuit 104, and a sensing circuit 106. The signal processing circuit 102 is coupled to the control circuit 104, and the sensing circuit 106 is coupled to the signal processing circuit 102 and coupled to the thermal sensing pixels P1 through signal transmission lines L1, L2 and the switching circuits SW1, SW2. The thermal sensing pixels P1 and the switching circuits SW1, SW2 are formed on a silicon substrate by a semiconductor process. Further, the silicon substrate, the signal processing circuit 102, the control circuit 104, and the sensing circuit 106 are mounted on a printed circuit board and packaged. In some embodiments, the signal processing circuit 102, the control circuit 104, and the sensing circuit 106 can also be independent groups

[0046]

[0047]

[0048] ​​​Alternatively, in some embodiments, the signal processing circuit 102, control circuit 104, and sensing circuit 106 may be fabricated on the semiconductor substrate of the microthermometer without being packaged together with the silicon substrate.

[0049] Furthermore, such as Figure 2 As shown, pixel P1 has connection point N1 and connection point N2, and the cut

[0050] Switching circuit SW1 is coupled to connection point N1, signal transmission lines L1 and L2, and shared connection line LC2. Switching circuit SW2 is coupled to connection point N2, signal transmission lines L1 and L2, and shared connection line LC1. Shared connection lines LC1 and LC2 can be used as bridging lines when connecting different thermal sensing pixels. Switching circuits SW1 and SW2 can be controlled by control circuit 104 to change the connection state, selectively connecting connection points N1 and N2 to signal transmission lines L1, L2, and shared connection line LC2.

[0051] By connecting LC1 or the shared connection line LC2, the connection state of the thermal sensing pixel P1 can be changed. In this embodiment, the switching circuits SW1 and SW2 are implemented with three switches respectively. By controlling the conduction state of the three switches, the connection points N1 and N2 can be connected to the signal transmission line L1, the signal transmission line L2, the shared connection line LC1, or the shared connection line LC2.

[0052] It is worth noting that, for ease of explanation, Figure 2 Only one thermal sensing pixel P1 is shown, but in practical applications, micro-thermal radiometers will include multiple thermal sensing pixels. When a micro-thermal radiometer includes multiple thermal sensing pixels, changing the coupling relationship between the thermal sensing pixels can correspondingly change the characteristics of the sensing signal output to the sensing circuit 106. For example, by connecting multiple thermal sensing pixels in series or in parallel, the signal characteristics (e.g., voltage magnitude) of the sensing signal provided to the sensing circuit 106 by the multiple thermal sensing pixels can be changed. The sensing circuit 106 can amplify the sensing signal, and the signal processing circuit 102 can, for example, perform analog-to-digital conversion on the sensing signal provided by the sensing circuit 106, but is not limited thereto.

[0053] For example, in Figure 3 and Figure 4 In this embodiment, the micro-thermal radiometer includes two thermal sensing pixels, P1 and P2. For example... Figure 3 and Figure 4 As shown, Figure 3 and Figure 4 The left side shows a schematic diagram of the connection between thermal sensing pixels P1 and P2, and the right side shows a schematic diagram of the circuit architecture of thermal sensing pixels P1, P2, switching circuits SW1 to SW4, signal transmission lines L1 and L2, and shared connection lines LC1 and LC2.

[0054] In Figure 3 In an embodiment, the control circuit 104 controls the switching circuit SW1 to connect the connection point N1 of the thermal sensing pixel P1 to the signal transmission line L2, controls the switching circuit SW2 to connect the connection point N2 of the thermal sensing pixel P2 to the signal transmission line L1, controls the switching circuit SW3 to connect the connection point N1 of the thermal sensing pixel P1 to the signal transmission line L2, and controls the switching circuit SW4 to connect the connection point N2 of the thermal sensing pixel P2 to the signal transmission line L1, so that the thermal sensing pixels P1 and P2 are connected in parallel.

[0055] In Figure 4 In an embodiment, the control circuit 104 controls the switching circuit SW1 to connect the connection point N1 of the thermal sensing pixel P1 to the shared connection line LC2, controls the switching circuit SW2 to connect the connection point N2 of the thermal sensing pixel P2 to the signal transmission line L1, controls the switching circuit SW3 to connect the connection point N1 of the thermal sensing pixel P1 to the shared connection line LC2, and controls the switching circuit SW4 to connect the connection point N2 of the thermal sensing pixel P2 to the signal transmission line L2, so that the thermal sensing pixels P1 and P2 are connected in series.

[0056] In some embodiments, the control circuit 104 can also control the switching circuits to make some of the thermal sensing pixels not participate in providing the sensing signal to the sensing circuit 106, for example, in Figure 3 In an embodiment, the control circuit 104 controls the switching circuit SW1 to connect the connection point N1 of the thermal sensing pixel P1 to the shared connection line LC2, controls the switching circuit SW2 to connect the connection point N2 of the thermal sensing pixel P2 to the signal transmission line L1, controls the switching circuit SW3 to connect the connection point N1 of the thermal sensing pixel P1 to the shared connection line LC2, and controls the switching circuit SW4 to connect the connection point N2 of the thermal sensing pixel P2 to the signal transmission line L2, so that the thermal sensing pixels P1 and P2 are connected in series.

[0057] In this way, by making the thermal sensing pixels P1 and P2 connected in series, in parallel, or disconnected from the sensing circuit 106, the signal characteristics of the sensing signal provided by the thermal sensing pixels P1 and P2 to the sensing circuit 106 can be changed, so that the sensing signal S1 provided by the thermal sensing pixels P1 and P2 is more suitable for signal processing by the signal processing circuit 102, for example, the sensing signal S1 provided by the thermal sensing pixels P1 and P2 can fall within the dynamic range of the signal processing circuit 102, but not limited thereto. In addition, in other embodiments, when a faulty or damaged thermal sensing pixel occurs, the control circuit 104 can control the switching circuit corresponding to the faulty or damaged thermal sensing pixel to disconnect the faulty or damaged thermal sensing pixel from the sensing circuit 106, so that the normally working thermal sensing pixels are connected to each other and bypass the faulty or damaged thermal sensing pixel, so that the faulty or damaged thermal sensing pixel does not affect the sensing quality of the microbolometer.

[0058] In addition, the number of thermal sensing pixels included in the microbolometer is not limited to the above embodiments, and in other embodiments, the microbolometer can include more thermal sensing pixels. For example Figure 5With Figure 6 As shown in the embodiments, the microbolometer can include thermal sensing pixels P1-P4, and similarly, the thermal sensing pixels P1-P4 are connected with corresponding switching circuits SW1-SW8. Since the thermal sensing pixels P1-P4 and the switching circuits SW1-SW8 are similar to those in the above embodiments, the coupling relationship thereof will not be described herein. The switching circuits SW1-SW8 can be controlled by the control circuit 104 to switch the connection points N1, N2 of the thermal sensing pixels P1-P4 to be connected to the signal transmission lines L1, L2, the shared connection lines LC1, LC2, or LC3. For example, in the embodiment, the parallelly connected thermal sensing pixels P1 and P2 and the parallelly connected thermal sensing pixels P3 and P4 can be connected in series, and in the embodiment, the seriesly connected thermal sensing pixels P1 and P2 and the seriesly connected thermal sensing pixels P3 and P4 can be connected in parallel. Figure 5 As shown in the embodiments, the microbolometer can include thermal sensing pixels P1-P4, and similarly, the thermal sensing pixels P1-P4 are connected with corresponding switching circuits SW1-SW8. Since the thermal sensing pixels P1-P4 and the switching circuits SW1-SW8 are similar to those in the above embodiments, the coupling relationship thereof will not be described herein. The switching circuits SW1-SW8 can be controlled by the control circuit 104 to switch the connection points N1, N2 of the thermal sensing pixels P1-P4 to be connected to the signal transmission lines L1, L2, the shared connection lines LC1, LC2, or LC3. For example, in the embodiment, the parallelly connected thermal sensing pixels P1 and P2 and the parallelly connected thermal sensing pixels P3 and P4 can be connected in series, and in the embodiment, the seriesly connected thermal sensing pixels P1 and P2 and the seriesly connected thermal sensing pixels P3 and P4 can be connected in parallel. Figure 6 As shown in the embodiments, the microbolometer can include thermal sensing pixels P1-P4, and similarly, the thermal sensing pixels P1-P4 are connected with corresponding switching circuits SW1-SW8. Since the thermal sensing pixels P1-P4 and the switching circuits SW1-SW8 are similar to those in the above embodiments, the coupling relationship thereof will not be described herein. The switching circuits SW1-SW8 can be controlled by the control circuit 104 to switch the connection points N1, N2 of the thermal sensing pixels P1-P4 to be connected to the signal transmission lines L1, L2, the shared connection lines LC1, LC2, or LC3. For example, in the embodiment, the parallelly connected thermal sensing pixels P1 and P2 and the parallelly connected thermal sensing pixels P3 and P4 can be connected in series, and in the embodiment, the seriesly connected thermal sensing pixels P1 and P2 and the seriesly connected thermal sensing pixels P3 and P4 can be connected in parallel.

[0059] Figure 7 is a flowchart of a thermal sensing method of a microbolometer according to an embodiment of the present application. The microbolometer includes a plurality of thermal sensing pixels and a plurality of switching circuits, each thermal sensing pixel has a first connection point and a second connection point, and the thermal sensing pixels and the switching circuits are formed on a silicon substrate by a semiconductor process. As shown in the above embodiments, the thermal sensing method of the microbolometer can include at least the following steps. First, a plurality of switching circuits are provided, the plurality of switching circuits are connected with a first signal transmission line, a second signal transmission line, at least one shared connection line, and a first connection point or a second connection point of a corresponding thermal sensing pixel (step S702). A sensing signal generated by the thermal sensing pixel is transmitted to a signal processing circuit through the first signal transmission line. The thermal sensing pixel can be, for example, a microbolometer pixel, but is not limited thereto. Then, the plurality of switching circuits are controlled to switch the first connection point or the second connection point of the corresponding thermal sensing pixel to be connected to the first signal transmission line, the second signal transmission line, or the shared connection line, so as to adjust the connection mode of the plurality of thermal sensing pixels and change the sensing signal provided by the plurality of thermal sensing pixels (step S704). For example, the connection mode of the plurality of thermal sensing pixels can be adjusted by the plurality of switching circuits according to the dynamic range of the signal processing circuit, and the connection mode of the plurality of thermal sensing pixels can include at least one of series connection, parallel connection, or disconnection.

[0060] In summary, the microbolometer according to the embodiments of the present application can adjust the connection mode of the plurality of thermal sensing pixels by switching the first connection point or the second connection point of the thermal sensing pixel corresponding to each switching circuit to be connected to different signal transmission lines or shared connection lines, so as to change the sensing signal provided by the plurality of thermal sensing pixels. This avoids the situation that the connection mode between the thermal sensing pixels cannot be adjusted after the microbolometer is packaged, and greatly improves the use flexibility of the microbolometer.

Claims

1.A microbolometer, comprising: a plurality of thermal sensing pixels, each thermal sensing pixel having a first connection point and a second connection point; and a plurality of switching circuits, each coupled to a first signal transmission line, a second signal transmission line, at least one shared connection line, and the first connection point or the second connection point of a corresponding thermal sensing pixel, to switch the first connection point or the second connection point of the corresponding thermal sensing pixel to the first signal transmission line, the second signal transmission line, or the shared connection line, to adjust a connection manner of the plurality of thermal sensing pixels, and to change a sensing signal provided by the plurality of thermal sensing pixels, wherein the connection manner of the plurality of thermal sensing pixels comprises at least one of series connection, parallel connection, or disconnection, and the plurality of thermal sensing pixels and the plurality of switching circuits are formed on a same silicon substrate by a semiconductor process. 2.The microbolometer of claim 1, further comprising: a sensing circuit coupled to the first signal transmission line and the second signal transmission line, to perform signal amplification processing on the sensing signal; and a signal processing circuit coupled to the sensing circuit, to perform analog-to-digital conversion processing on the sensing signal provided by the sensing circuit. 3.The microbolometer of claim 2, further comprising: a control circuit coupled to the plurality of switching circuits, to control the plurality of switching circuits to adjust the connection manner of the plurality of thermal sensing pixels according to a dynamic range of the signal processing circuit. 4.The microbolometer of claim 1, wherein the plurality of thermal sensing pixels further comprises a reference pixel. 5.A thermal sensing method of a microbolometer, the microbolometer comprising a plurality of thermal sensing pixels and a plurality of switching circuits, each thermal sensing pixel having a first connection point and a second connection point, the thermal sensing method of the microbolometer comprising: providing a plurality of switching circuits, the plurality of switching circuits connecting a first signal transmission line, a second signal transmission line, at least one shared connection line, and the first connection point or the second connection point of a corresponding thermal sensing pixel; and controlling the plurality of switching circuits to switch the first connection point or the second connection point of the corresponding thermal sensing pixel to a first signal transmission line, a second signal transmission line, or a shared connection line, to adjust a connection manner of the plurality of thermal sensing pixels, and to change a sensing signal provided by the plurality of thermal sensing pixels, wherein the connection manner of the plurality of thermal sensing pixels comprises at least one of series connection, parallel connection, or disconnection, and the plurality of thermal sensing pixels and the plurality of switching circuits are formed on a same silicon substrate by a semiconductor process. 6.The thermal sensing method of the microbolometer of claim 5, wherein the sensing signal generated by the plurality of thermal sensing pixels is transmitted to a signal processing circuit for analog-to-digital conversion processing. 7.The thermal sensing method of the microbolometer of claim 6, comprising: controlling the plurality of switching circuits to adjust the connection manner of the plurality of thermal sensing pixels according to a dynamic range of the signal processing circuit. 8.The thermal sensing method of the microbolometer of claim 7, wherein the plurality of thermal sensing pixels comprises microbolometer pixels. ​ 9. The method of thermal sensing of a microbolometer according to claim 5, wherein the plurality of thermal sensing pixels further comprises a reference pixel.

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