Infrared detection element

Abstract

The diode (11) is arranged on the substrate (1) and is thermally insulated from the substrate (1). The positive feedback circuit (18) provides a positive feedback loop in a manner such that when the current of the diode (11) decreases due to a temperature change of the diode (11), the current of the diode (11) is further reduced, and when the current of the diode (11) increases due to a temperature change of the diode (11), the current of the diode (11) is further increased.

Description

Technical Field

[0001] The present disclosure relates to a thermal infrared detection element that converts infrared rays into heat for detection. Background Art

[0002] Infrared detection elements are broadly categorized as quantum and thermal types. Quantum infrared detection elements are cooled and require cooling equipment. Thermal infrared detection elements, on the other hand, are uncooled and do not require cooling equipment, allowing for miniaturization. Thermal infrared detection elements convert infrared light absorbed by an infrared absorber into heat and convert the resulting temperature change into an electrical signal.

[0003] In recent years, infrared detection elements have been developed with a focus on lowering prices for consumer applications, resulting in improved detection capabilities. In temperature sensors that use diodes as infrared detection elements, the temperature change rate of each diode is small, so multiple diodes are connected in series to increase detection sensitivity.

[0004] It is required to connect as many diodes as possible in series and configure them within the limited area of ​​the temperature detection part of the infrared detection element. In response to this, an infrared detection element is proposed in which the adjacent first and second diodes are connected to each other using a metal film provided on the surface of a recess formed throughout the P-type layer of the first diode and the N-type layer of the second diode (for example, refer to patent document 1). As a result, the spacing between adjacent diodes is smaller than when the diodes are separated by an oxide film. Therefore, a plurality of diodes can be formed at a high density, so the detection sensitivity of the infrared detection element can be improved.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-265094 Summary of the Invention

[0008] In conventional infrared detection elements, to improve detection sensitivity, it is necessary to increase the number of diodes connected in series in the temperature detection unit. Increasing the number of diodes increases the size of the infrared detection element and requires a higher power supply voltage.

[0009] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide an infrared detection element capable of improving detection sensitivity without increasing the number of diodes.

[0010] The present disclosure provides an infrared detection element, characterized in that it comprises: a substrate; a diode, which is arranged on the substrate and is thermally insulated from the substrate; and a positive feedback circuit, which provides a positive feedback loop in a manner such that when the current of the diode decreases due to a temperature change of the diode, the current of the diode is further reduced, and when the current of the diode increases due to a temperature change of the diode, the current of the diode is further increased.

[0011] The infrared detection element of the present disclosure configured as described above can improve detection sensitivity without increasing the number of diodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a perspective view showing the infrared imaging device according to the first embodiment.

[0013] Figure 2 This is a plan view showing the infrared detection element according to the first embodiment.

[0014] Figure 3 It is along Figure 1 Cross-sectional view of I-II.

[0015] Figure 4 This is a circuit diagram showing the infrared detection element according to the first embodiment.

[0016] Figure 5 is a circuit diagram showing a current mirror circuit.

[0017] Figure 6 is a circuit diagram showing a current mirror circuit.

[0018] Figure 7 This is a diagram showing the voltage-current characteristics of the diode of the infrared detection element according to the first embodiment.

[0019] Figure 8 This is a circuit diagram showing an infrared detection element according to the second embodiment.

[0020] Figure 9 is a circuit diagram showing a current mirror circuit.

[0021] Figure 10 is a circuit diagram showing a current mirror circuit.

[0022] Figure 11 This is a circuit diagram showing an infrared detection element according to a third embodiment.

[0023] Figure 12 This is a circuit diagram showing a modified example of the infrared detection element of the third embodiment.

[0024] Figure 13 This is a circuit diagram showing an infrared detection element according to a fourth embodiment.

[0025] Figure 14 This is a circuit diagram showing a modified example of the infrared detection element of the fourth embodiment.

[0026] Figure 15 This is a circuit diagram showing an infrared detection element according to a fifth embodiment.

[0027] Figure 16 This is a circuit diagram showing an infrared detection element according to a sixth embodiment.

[0028] Figure 17 This is a circuit diagram showing a modified example of the infrared detection element of the sixth embodiment.

[0029] Figure 18 This is a circuit diagram showing an infrared detection element according to a seventh embodiment.

[0030] Figure 19 This is a circuit diagram showing an infrared detection element according to an eighth embodiment.

[0031] Figure 20 This is a circuit diagram showing an infrared detection element according to a ninth embodiment.

[0032] (Explanation of Symbols)

[0033] 1: Substrate; 8: Infrared detection unit; 11: Diode; 18: Positive feedback circuit; 20: Current mirror circuit; 21: Control circuit; 22: Current source; 23: Differential integrator circuit; 24: Drive line; 26: Virtual drive line; 27: Signal line; Mdp, Mmp, Mcp, Mmp′, Mcp′: P-type MOS transistors; Mdn, Mmn, Mcn, Mmn′, Mcn′, Msu: N-type MOS transistors; R pix : resistor; SW2: switch. DETAILED DESCRIPTION

[0034] The infrared detection element according to the embodiment will be described with reference to the accompanying drawings. The same or corresponding components will be denoted by the same reference numerals and repeated description will be omitted.

[0035] Implementation method 1.

[0036] Figure 1This is a perspective view of an infrared imaging device according to Embodiment 1. A plurality of infrared detection elements 2 are arranged two-dimensionally in an array or matrix on a substrate 1. Selection lines 3 and signal lines 4 are provided along the plurality of infrared detection elements 2. The selection lines 3 are connected to a drive scanning circuit 5. The signal lines 4 are connected to a signal scanning circuit 6. The drive scanning circuit 5 and the signal scanning circuit 6 are provided around the plurality of infrared detection elements 2. The output signals of the infrared detection elements 2 selected by the drive scanning circuit 5 and the signal scanning circuit 6 are amplified by an output amplifier 7 including an integration circuit.

[0037] Figure 2 1 is a top view of the infrared detection element of embodiment 1. The infrared detection element 2 has a heat-insulating structure formed by micromachining technology. An infrared detection unit 8 is formed on the heat-insulating structure. The infrared detection unit 8 is heat-insulated from the substrate 1 by the heat-insulating structure. When infrared rays are incident, the temperature of the infrared detection unit 8 rises. The infrared detection unit 8 detects the temperature rise and outputs it as an electrical signal. The output signals of the plurality of infrared detection elements 2 are read out in a time series by the scanning action of the drive scanning circuit 5 and the signal scanning circuit 6 to obtain an infrared image signal.

[0038] Figure 3 It is along Figure 1 The infrared detection element 2 includes an infrared detection region and a circuit region. The substrate 1 is, for example, an SOI (Silicon On Insulator) substrate. In the infrared detection region, a cavity 9 is provided in the substrate 1. The infrared detection portion 8 is disposed in the cavity 9 in a state separated from the substrate 1 and supported by the support legs 10. The cavity 9 is the aforementioned heat-insulating structure.

[0039] The infrared detection unit 8 is a pixel having multiple diodes 11 connected in series as temperature sensors. Diodes 11 may be Schottky diodes, tunnel diodes, or the like. Instead of diodes 11, other thermoelectric conversion elements whose electrical characteristics change with temperature may be provided. Thin-film wiring 13, an interlayer insulating film 14, and a protective film 15 are sequentially provided on an insulating film 12 covering the diodes 11. Thin-film wiring 13 is connected to the diodes 11. An infrared absorption unit 16 having an umbrella structure for absorbing infrared light is provided on the protective film 15.

[0040] Support pin 10 comprises a stacked structure of insulating film 12, interlayer insulating film 17, thin-film wiring 13, interlayer insulating film 14, and protective film 15. Insulating film 12, interlayer insulating film 17, interlayer insulating film 14, and protective film 15 may be made of, for example, silicon oxide or silicon nitride. Thin-film wiring 13 may be made of a metal such as aluminum, Ti, TiN, Ni, Cr, or Pt, or polysilicon.

[0041] The circuit region includes a positive feedback circuit 18 and wiring 19 connected to the positive feedback circuit 18. The positive feedback circuit 18 includes, for example, a scanning circuit, a current source circuit, a power supply circuit, an integrating circuit, or a MOS (Metal Oxide Semiconductor) transistor.

[0042] In the infrared detection element 2, incident infrared light is absorbed by the infrared absorption portion 16 and converted into heat, which is then transferred to the infrared detection portion 8. The temperature of the infrared detection portion 8 rises, causing the electrical characteristics of the diode 11 included in the infrared detection portion 8 to change. Thin-film wiring 13, which is connected to the p-side and n-side of the diode 11, is connected to wiring 19 via support pins 10. Changes in the electrical characteristics of the diode 11 are output as electrical signals via the thin-film wiring 13 and wiring 19 to the positive feedback circuit 18 for use in detecting incident infrared light.

[0043] Figure 4 1 is a circuit diagram showing an infrared detection element according to Embodiment 1. The infrared detection unit 8 includes a plurality of diodes 11 connected in series. The anodes of the diodes 11 are connected to a first power supply V DD The cathode voltage of the diode 11 is output as the output voltage Vpix of the infrared detection element 2 .

[0044] The positive feedback circuit 18 includes a P-type MOS transistor Mdp and a current mirror circuit 20. The P-type MOS transistor Mdp receives the cathode voltage of the diode 11 from its gate. The source of the P-type MOS transistor Mdp is connected to the second power supply VDS.

[0045] The drain current of the P-type MOS transistor Mdp is input to the current mirror circuit 20 , and the output of the current mirror circuit 20 is connected to the cathode of the diode 11 . Figure 5 as well as Figure 6 is a circuit diagram showing a current mirror circuit. Figure 5 Current mirror circuit 20 includes N-type MOS transistors Mmn and Mcn. The drain and gate of N-type MOS transistor Mmn are connected to each other and to the gate of N-type MOS transistor Mcn. The sources of N-type MOS transistors Mmn and Mcn are grounded. Input current Iin is input to the drain of N-type MOS transistor Mmn, and output current Iout is input to the drain of N-type MOS transistor Mcn. Figure 6The current mirror circuit 20 includes N-type MOS transistors Mmn, Mcn, Mmn′, and Mcn′. The drain and gate of the N-type MOS transistor Mmn are connected to each other and to the gate of the N-type MOS transistor Mcn. The sources of the N-type MOS transistors Mmn and Mcn are grounded. The drain and gate of the N-type MOS transistor Mmn′ are connected to each other and to the gate of the N-type MOS transistor Mcn′. The sources of the N-type MOS transistors Mmn′ and Mcn′ are connected to the drains of the N-type MOS transistors Mmn and Mcn, respectively. The input current Iin is input to the drain of the N-type MOS transistor Mmn′, and the output current Iout is input to the drain of the N-type MOS transistor Mcn′.

[0046] In the infrared detection element of such a structure, when the temperature of the plurality of diodes 11 rises, the forward voltage Vf of the plurality of diodes 11 decreases. DD The gate voltage of the PMOS transistor Mdp, which is the voltage obtained by subtracting the voltage Vf from the voltage Vdp, increases, and the current Id of the PMOS transistor Mdp decreases. In response to this current decrease, the current mirror circuit 20 reduces the current If of the diode 11. As a result, the forward voltage Vf further decreases.

[0047] Furthermore, when the temperature of diodes 11 decreases, the forward voltage Vf of the plurality of diodes 11 increases. Consequently, the gate voltage of P-type MOS transistor Mdp decreases, and the current Id of P-type MOS transistor Mdp increases. Current mirror circuit 20 increases the current If of diodes 11 in response to this current increase. This further increases the forward voltage Vf of diodes 11. This creates a positive feedback loop for the changes in the forward voltage Vf and current If of diodes 11.

[0048] Figure 7 This is a diagram showing the voltage-current characteristics of the diode of the infrared detection element of Embodiment 1. The comparative example does not have the positive feedback circuit 18 of the infrared detection element of Embodiment 1, and is configured to drive the diode 11 with a constant current by a current source. In the comparative example, the voltage Vf of the diode decreases only when the temperature of the diode 11 rises. In this embodiment, when the temperature of the diode 11, which serves as a temperature sensor, rises due to incident infrared rays, the forward voltage Vf of the diode 11 decreases. Therefore, the voltage Vf of the diode 11 decreases from the power supply V DDThe voltage obtained by subtracting voltage Vf from the voltage of the PMOS transistor Mdp increases, and the current Id of the PMOS transistor Mdp decreases. Current mirror circuit 20 reduces current If of diode 11 in response to this current reduction. This further reduces forward voltage Vf. Consequently, a voltage change greater than the voltage change obtained from a single diode due to absorption of incident infrared light during constant current operation of the diode in the comparative example can be achieved. As a result, the detection sensitivity of the infrared detection element can be improved without increasing the number of diodes.

[0049] In order to stabilize the circuit operation, it is preferred to set the impedance of the diode 11 to Z, the mutual conductance of the P-type MOS transistor Mdp to gmd, and the current mirror current ratio (output / input) to κ, satisfying the relationship 0<κ·gmd·Z<1.

[0050] Implementation method 2.

[0051] Figure 8 1 is a circuit diagram showing an infrared detection element according to Embodiment 2. The cathodes of the plurality of diodes 11 are grounded. The anode voltage of the diodes 11 is output as the output voltage Vpix of the thermal infrared detection element.

[0052] The positive feedback circuit 18 includes an N-type MOS transistor Mdn and a current mirror circuit 20. The gate of the N-type MOS transistor Mdn receives the anode voltage of the diode 11. The source of the N-type MOS transistor Mdn is grounded.

[0053] The drain current of the N-type MOS transistor Mdn is input to the current mirror circuit 20 , and the output of the current mirror circuit 20 is connected to the anode of the diode 11 . Figure 9 as well as Figure 10 is a circuit diagram showing a current mirror circuit. Figure 9 The current mirror circuit 20 includes P-type MOS transistors Mmp and Mcp. The drain and gate of the P-type MOS transistor Mmp are connected to each other and to the gate of the P-type MOS transistor Mcp. The sources of the P-type MOS transistors Mmp and Mcp are respectively connected to the power supply V DD The input current Iip is drawn from the drain of the P-type MOS transistor Mmp, and the output current Iout is drawn from the drain of the P-type MOS transistor Mcp. Figure 10 The current mirror circuit 20 includes P-type MOS transistors Mmp, Mcp, Mmp′, and Mcp′. The drain and gate of the P-type MOS transistor Mmp are connected to each other and to the gate of the P-type MOS transistor Mcp. The sources of the P-type MOS transistors Mmp and Mcp are respectively connected to the power supply V DDThe drain and gate of the P-type MOS transistor Mmp′ are connected to each other and to the gate of the P-type MOS transistor Mcp′. The sources of the P-type MOS transistors Mmp′ and Mcp′ are connected to the drains of the P-type MOS transistors Mmp and Mcp, respectively. The input current Iip is drawn from the drain of the P-type MOS transistor Mmp′, and the output current Iout is drawn from the drain of the P-type MOS transistor Mcp′.

[0054] In this infrared detection element, when the temperature of the multiple diodes 11 rises, the forward voltage Vf of the multiple diodes 11 decreases. Consequently, the gate voltage of the NMOS transistor Mdn decreases, and the current Id of the NMOS transistor Mdn decreases. In response to this current decrease, the current mirror circuit 20 reduces the current If of the diodes 11. As a result, the voltage Vf further decreases.

[0055] Furthermore, as the temperature of diodes 11 decreases, the forward voltage Vf of the plurality of diodes 11 increases. Consequently, the gate voltage of NMOS transistor Mdn increases, and the current Id of NMOS transistor Mdn increases. Current mirror circuit 20 increases the current If of diodes 11 in response to this current increase. Consequently, the forward voltage Vf of diodes 11 further increases.

[0056] Thus, a positive feedback loop is provided for the change of the forward voltage Vf and the current If of the diode 11. Figure 7 As described in Embodiment 1, a voltage change greater than the voltage change obtained from a single diode due to incident infrared absorption by the diode in the comparative example during constant current operation can be obtained. As a result, the detection sensitivity of the infrared detection element can be improved without increasing the number of diodes.

[0057] In order to stabilize the circuit operation, it is preferred to set the impedance of the diode 11 to Z, the mutual conductance of the N-type MOS transistor Mdn to gmd, and the current mirror current ratio (output / input) to κ, satisfying the relationship 0<κ·gmd·Z<1.

[0058] Implementation method 3.

[0059] Figure 11 : is a circuit diagram showing an infrared detection element according to Embodiment 3. Resistor R pix Connected between the cathode of the diode 11 and the output of the current mirror circuit 20. When the temperature of the diode 11 rises, the diode voltage Vf decreases, and the current If of the diode 11 decreases due to the positive feedback loop, and the diode voltage Vf further decreases. At this time, the output voltage Vpix of the infrared detection element is determined by the diode voltage Vf and the resistance R generated by the current If of the diode 11. pixWhen the current If of diode 11 decreases, the resistor R pix The voltage drop at the φ1 is also reduced, so the change in the output voltage Vpix of the infrared detection element becomes larger. This makes it possible to achieve a highly sensitive infrared detection element. The other structures and effects are the same as those of the first embodiment.

[0060] If the current If of the diode 11 is in the order of several μA, a high resistance of several kΩ or so is used as the resistor R. pix This can increase the resistance R generated by the current If of the diode 11. pix The voltage drop at .

[0061] Figure 12 : is a circuit diagram showing a modified example of the infrared detection element of the third embodiment. pix It is connected between the anode of the diode 11 and the output of the current mirror circuit 20. This makes it possible to realize a highly sensitive infrared detection element. The other structures and effects are the same as those of the second embodiment.

[0062] Implementation method 4.

[0063] Figure 13 This is a circuit diagram showing an infrared detection element according to Embodiment 4. It is composed of an N-type MOS transistor. Figure 11 The resistor R in the third embodiment shown pix The temperature rise caused by the incident infrared rays is not limited to that caused by the infrared detection element. When the ambient temperature of the infrared detection element increases, the current If of the diode 11 also decreases, and the gain changes. Therefore, the control circuit 21 controls the resistor R according to the ambient temperature. pix The gate voltage of the N-type MOS transistor V AMB Changes, the higher the ambient temperature, the smaller the resistance R pix The resistance value is thus reduced. This reduces gain variations due to changes in ambient temperature. Furthermore, an N-type MOS transistor is used in a linear operating range relative to ambient temperature changes. Other structures and effects are the same as those of embodiment 3.

[0064] Figure 14 This is a circuit diagram showing a modified example of the infrared detection element of the fourth embodiment. It is composed of N-type MOS transistors. Figure 12 The resistor R of the modified example of the third embodiment shown in FIG. pix The control circuit 21 adjusts the gate voltage V of the N-type MOS transistor according to the ambient temperature. AMB Changes, the higher the ambient temperature, the smaller the resistance R pix The resistance value is thus reduced. This can reduce the gain change caused by changes in ambient temperature. The other structures and effects are the same as those of the modified example of embodiment 3.

[0065] Implementation method 5.

[0066] Figure 15 : is a circuit diagram showing an infrared detection element according to Embodiment 5. The anode of the diode 11 and the source of the P-type MOS transistor Mdp are connected to the same power supply V DD As a result, the anode voltage of diode 11 is equal to the source voltage of P-type MOS transistor Mdp. Therefore, the sensitivity of the infrared detection element does not change when the power supply voltage fluctuates. In addition, there is no gain change due to power supply voltage fluctuations. The other structures and effects are the same as those of embodiment 3.

[0067] Implementation method 6.

[0068] Figure 16 : This is a circuit diagram showing an infrared detection element of embodiment 6. The current mirror circuit 20 has N-type MOS transistors Mmn, Mcn, Mmn′, and Mcn′ connected in cascode. The drain and gate of the N-type MOS transistor Mmn are connected to each other and to the gate of the N-type MOS transistor Mcn. The sources of the N-type MOS transistors Mmn and Mcn are grounded respectively. The drain and gate of the N-type MOS transistor Mmn′ are connected to each other and to the gate of the N-type MOS transistor Mcn′. The sources of the N-type MOS transistors Mmn′ and Mcn′ are connected to the drains of the N-type MOS transistors Mmn and Mcn respectively. The drain of the N-type MOS transistor Mmn′ is connected to the drain of the P-type MOS transistor Mdp, and the drain of the N-type MOS transistor Mcn′ is connected to the resistor R pix As a result, the drain voltages of the NMOS transistors Mmn and Mcn in the current mirror circuit 20 coincide with each other, and the current replication accuracy of the current mirror circuit 20 improves. The remaining configuration and effects are the same as those of the third embodiment.

[0069] Figure 17 This is a circuit diagram showing a modified example of the infrared detection element of the sixth embodiment. The current mirror circuit 20 includes cascade-connected P-type MOS transistors Mmp, Mcp, Mmp′, and Mcp′. The drain and gate of the P-type MOS transistor Mmp are connected to each other and to the gate of the P-type MOS transistor Mcp. The sources of the P-type MOS transistors Mmp and Mcp are connected to the power supply V DD The drain and gate of the P-type MOS transistor Mmp′ are connected to each other and to the gate of the P-type MOS transistor Mcp′. The sources of the P-type MOS transistors Mmp′ and Mcp′ are connected to the drains of the P-type MOS transistors Mmp and Mcp, respectively. The drain of the P-type MOS transistor Mmp′ is connected to the drain of the N-type MOS transistor Mdn, and the drain of the P-type MOS transistor Mcp′ is connected to the resistor Rpix As a result, the drain voltages of the PMOS transistors Mmp and Mcp in the current mirror circuit 20 coincide with each other, and the current replication accuracy of the current mirror circuit 20 improves. The other structures and effects are the same as those of the fourth embodiment.

[0070] Implementation method 7.

[0071] Figure 18 : This is a circuit diagram showing an infrared detection element of embodiment 7. The current mirror circuit 20 has N-type MOS transistors Mmn and Mcn. The drain and gate of the N-type MOS transistor Mmn are connected to each other and to the gate of the N-type MOS transistor Mcn. The sources of the N-type MOS transistors Mmn and Mcn are grounded respectively. The drain of the N-type MOS transistor Mmn is connected to the drain of the P-type MOS transistor Mdp, and the drain of the N-type MOS transistor Mcn is connected to the infrared detection unit 8. The N-type MOS transistor Msu is connected in the form of a diode between the cathode of the diode 11 and the gates of the N-type MOS transistors Mmn and Mcn of the current source of the current mirror circuit 20. The gate and drain of the N-type MOS transistor Msu are connected to the cathode of the diode 11, and the source of the N-type MOS transistor Msu is connected to the gates of the N-type MOS transistors Mmn and Mcn. The threshold voltage of the MOS transistor Msu is set to be higher than the power supply V applied to the anode of the diode 11. DD The voltage is lower than the normal operating voltage range, which is the voltage range between the upper and lower limits of the cathode voltage Vpix of the diode 11 that changes due to the incidence of infrared light from an object within the temperature range (lower limit temperature to upper limit temperature) of the infrared detection element. The remaining structure is the same as that of the first embodiment.

[0072] In the case of the first embodiment, if = 0, Vg = 0, Vpix = V DD Even in the case of a startup failure, a stable point exists. In this embodiment, when a startup failure occurs, MOS transistor Msu is turned on, forcibly lowering voltage Vpix. This allows current to flow through MOS transistors Mdp, Mmn, and Mcn in this order, reliably activating the infrared detection element. Other effects are achieved similar to those of Embodiment 1.

[0073] Implementation method 8.

[0074] Figure 191 is a circuit diagram showing an infrared detection element according to an eighth embodiment. A plurality of infrared detection units 8 are arranged in an array. A positive feedback circuit 18, a current source 22, and a differential integration circuit 23 are provided for each column of the plurality of infrared detection units 8 arranged in an array. Each infrared detection unit 8 has a plurality of diodes 11 connected in series. Therefore, a positive feedback circuit 18 is provided for each column of the plurality of diodes 11 connected in series. The MOS transistors Mmn and Mcn of the current mirror circuit 20 have the same specifications, and the current mirror ratio κ of the current mirror circuit 20 is 1.

[0075] The anodes of the diodes 11 of the plurality of infrared detection units 8 are sequentially connected to the driving line 24 along the arrangement direction of the plurality of infrared detection units 8. One end of the driving line 24 is connected to the power supply V DD The sources of the P-type MOS transistors Mdp of the multiple positive feedback circuits 18 are sequentially connected to a circuit power supply line 25 along the arrangement direction of the multiple infrared detection units 8. One end of the circuit power supply line 25 is connected to a power supply VDS. The multiple current sources 22 are sequentially connected to a dummy drive line 26 along the arrangement direction of the multiple infrared detection units 8.

[0076] The circuit power supply line 25, the drive line 24, and the virtual drive line 26 have the same resistance. The current source 22 includes a MOS transistor Mcd having the same specifications as the MOS transistors Mmn and Mcn of the corresponding current mirror circuit 20. The gates of the MOS transistors Mmn and Mcn of the corresponding current mirror circuit 20 are connected to the gate of the N-type MOS transistor Mcd of the current source 22. The source of the N-type MOS transistor Mcd is grounded, and the drain of the N-type MOS transistor Mcd is connected to the virtual drive line 26. The current value of the current source 22 is set so that the potential distribution of the virtual drive line 26 along the arrangement direction of the multiple infrared detection units 8 is the same as the potential distribution of the drive line 24. Therefore, the voltage drop of the drive line 24 is simulated on the virtual drive line 26.

[0077] The connection points between the diodes 11 of the infrared detection units 8 and the drive lines 24, and the connection points between the corresponding current sources 22 and the virtual drive lines 26, are located in the same position along the arrangement direction of the plurality of infrared detection units 8. The differential integrator 23 amplifies and outputs the difference between the output voltage of the corresponding current mirror circuit 20 and the voltage at the connection point between the corresponding current source 22 and the virtual drive line 26. Thus, even if a change in the current of a particular diode 11 causes a change in the voltage of the drive line 24, the effect of the other diodes 11 on the output of the infrared detection units 8 can be eliminated.

[0078] Implementation method 9.

[0079] Figure 20: is a circuit diagram showing an infrared detection element of Embodiment 9. A signal line 27 connects the cathode of the diode 11 to the corresponding differential integration circuit 23. A switch SW1 is connected to a power supply V that supplies a voltage to the diode 11. DD and the anode of the diode 11. The switch SW2 for turning on is connected between the dummy drive line 26 and the signal line 27. Specifically, one end of the switch SW2 is connected to the signal line 27, and the other end of the switch SW2 is connected to the differential integrator circuit 23, the drain of the N-type MOS transistor Mcd, and the dummy drive line 26.

[0080] During the horizontal blanking period, switch SW2 short-circuits signal line 27 and dummy drive line 26, forcibly lowering the gate voltage of P-type MOS transistor Mdp and allowing current to flow. This allows the infrared detection element to be properly activated. For example, switch SW2 is activated at a timing opposite to that of switch SW1.

Claims

1. An infrared detection element, characterized in that: have: substrate; a diode, disposed on the substrate and thermally insulated from the substrate; and A positive feedback circuit provides a positive feedback loop in such a manner that when the current of the diode decreases due to a temperature change of the diode, the current of the diode is further reduced, and when the current of the diode increases due to a temperature change of the diode, the current of the diode is further increased. The positive feedback circuit has: a P-type MOS transistor, a cathode voltage of the diode being inputted through a gate, and a source of the P-type MOS transistor being connected to a power supply; as well as A current mirror circuit is input with the drain current of the P-type MOS transistor as input, and the output of the current mirror circuit is connected to the cathode of the diode, The cathode of the diode and the gate of the P-type MOS transistor are connected to the output of the infrared detection element.

2. The infrared detection element according to claim 1, wherein The impedance of the diode is set to Z, the mutual conductance of the P-type MOS transistor is set to gmd, the current mirror current ratio of the current mirror circuit is set to κ, and 0<κ･gmd･Z<1.

3. An infrared detection element, characterized in that: have: substrate; a diode, disposed on the substrate and thermally insulated from the substrate; and A positive feedback circuit provides a positive feedback loop in such a manner that when the current of the diode decreases due to a temperature change of the diode, the current of the diode is further reduced, and when the current of the diode increases due to a temperature change of the diode, the current of the diode is further increased. The positive feedback circuit has: An N-type MOS transistor, the anode voltage of the diode is inputted through the gate, and the source of the N-type MOS transistor is grounded; as well as A current mirror circuit is input with the drain current of the N-type MOS transistor as input, and the output of the current mirror circuit is connected to the anode of the diode, The anode of the diode and the gate of the N-type MOS transistor are connected to the output of the infrared detection element.

4. The infrared detection element according to claim 3, wherein The impedance of the diode is set to Z, the mutual conductance of the N-type MOS transistor is set to gmd, the current mirror current ratio of the current mirror circuit is set to κ, and 0<κ･gmd･Z<1.

5. The infrared detection element according to any one of claims 1 to 4, characterized in that: The infrared detection element further includes a resistor connected between the diode and an output of the current mirror circuit.

6. The infrared detection element according to claim 5, wherein: The resistor is composed of a MOS transistor. The infrared detection element further includes a control circuit that changes the gate voltage of the MOS transistor according to the ambient temperature of the infrared detection element when the infrared detection element is used, and reduces the resistance value of the resistor as the ambient temperature increases.

7. The infrared detection element according to claim 1, wherein An anode of the diode and a source of the P-type MOS transistor are connected to the same potential.

8. The infrared detection element according to claim 2, wherein An anode of the diode and a source of the P-type MOS transistor are connected to the same potential.

9. The infrared detection element according to any one of claims 1 to 4, characterized in that: The current mirror circuit has cascade-connected transistors.

10. The infrared detection element according to claim 5, wherein The current mirror circuit has cascade-connected transistors.

11. The infrared detection element according to claim 6, wherein The current mirror circuit has cascade-connected transistors.

12. The infrared detection element according to claim 7 or 8, characterized in that The current mirror circuit has cascade-connected transistors.

13. The infrared detection element according to claim 1 or 2, characterized in that: The infrared detection element further includes a MOS transistor connected in a diode-like manner between a cathode of the diode and a gate of the transistor of the current mirror circuit. The threshold voltage of the MOS transistor is set to be lower than the power supply voltage applied to the anode of the diode and higher than the normal operating voltage range, and the normal operating voltage range is the voltage range of the upper limit value and the lower limit value of the cathode voltage of the diode that changes due to the incidence of infrared rays from an object within the temperature range that is the detection object of the infrared detection element.

14. An infrared detection element comprising: substrate; A plurality of infrared detection units are arranged in an array on the substrate; and A positive feedback circuit is provided for each column of the plurality of infrared detection units arranged in an array. Each infrared detection unit has a plurality of diodes connected in series and thermally insulated from the substrate. Each positive feedback circuit provides a positive feedback loop in such a manner that when the current of the diode of the corresponding infrared detection unit decreases due to a temperature change of the diode, the current of the diode is further reduced, and when the current of the diode increases due to a temperature change of the diode, the current of the diode is further increased. Each positive feedback circuit has: a P-type MOS transistor, a cathode voltage of the diode being inputted through a gate thereof, and a source of the P-type MOS transistor being connected to a power supply; and A current mirror circuit is input with the drain current of the P-type MOS transistor as input, and the output of the current mirror circuit is connected to the cathode of the diode, The cathode of the diode and the gate of the P-type MOS transistor are connected to the output of the infrared detection element.

15. The infrared detection element according to claim 14, wherein The infrared detection element further comprises: a driving line, sequentially connecting the anodes of the diodes of the plurality of infrared detection parts along the arrangement direction of the plurality of infrared detection parts; a plurality of current sources, respectively provided for the plurality of positive feedback circuits; a virtual driving line, sequentially connected to the multiple current sources along the arrangement direction; as well as A plurality of differential integration circuits are respectively provided for the plurality of infrared detection parts. The driving line and the dummy driving line have the same resistance, The current values ​​of the plurality of current sources are set so that the potential distribution of the virtual driving line along the arrangement direction is the same as the potential distribution of the driving line. The differential integration circuit outputs a difference between an output voltage of the corresponding current mirror circuit and a voltage at a connection point between the corresponding current source and the virtual driving line.

16. The infrared detection element according to claim 15, wherein The current source has a MOS transistor with the same specifications as the corresponding MOS transistor of the current mirror circuit. The gate of the corresponding MOS transistor of the current mirror circuit is commonly connected to the gate of the MOS transistor of the current source.

17. The infrared detection element according to claim 15 or 16, characterized in that: Also features: a signal line connecting the cathode of the diode to the corresponding differential integration circuit; and A switch is connected between the virtual driving line and the signal line.

18. An infrared detection element, characterized in that: have: substrate; A plurality of infrared detection units are arranged in an array on the substrate; and A positive feedback circuit is provided for each column of the plurality of infrared detection units arranged in an array. Each infrared detection unit has a plurality of diodes connected in series and thermally insulated from the substrate. Each positive feedback circuit provides a positive feedback loop in such a manner that when the current of the diode of the corresponding infrared detection unit decreases due to a temperature change of the diode, the current of the diode is further reduced, and when the current of the diode increases due to a temperature change of the diode, the current of the diode is further increased. Each positive feedback circuit has: An N-type MOS transistor, the anode voltage of the diode is inputted through the gate, and the source of the N-type MOS transistor is grounded; as well as A current mirror circuit is input with the drain current of the N-type MOS transistor as input, and the output of the current mirror circuit is connected to the anode of the diode, The anode of the diode and the gate of the N-type MOS transistor are connected to the output of the infrared detection element.

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