JP2011232157A - Infrared-ray imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared-ray imaging apparatus that can suppress image deterioration by blocking disturbance infrared-ray more appropriately.SOLUTION: A surface of a semiconductor substrate 1 is provided with a blocking film 7 and a reflection film 8 in a plane form so as to cover an opening of a cavity part 1a. That is, the blocking film 7 is mechanically and thermally connected to a plane of the semiconductor substrate 1 that faces an optical system 150. The reflection film 8 is formed so as to cover the entire surface of the blocking film 7. An imaging pixel opening 101a is formed through the blocking film 7 and the reflection film 8. The blocking film 7 and the reflection film 8 let only an optical system passing infrared-ray 152 go through the imaging pixel opening 101a to a temperature detecting part 5 in the cavity part 1a. At places other than the imaging pixel opening 101a in the entire plane, the blocking film 7 and the reflection film 8 block/reflect the disturbance infrared-ray.

Description

  The present invention relates to an infrared imaging device using a thermal detector as temperature change detection means.

  The thermal detector detects a temperature change due to infrared rays emitted from a subject using a hollow structure that is thermally separated from a semiconductor substrate. Such temperature change detection means include a bolometer method in which a bolometer is formed in a hollow structure to detect a resistance change, or a voltage change in a state where a forward current is passed by forming a PN junction diode on the hollow structure. A diode method or the like has been proposed. These thermal detectors generally have a configuration in which a plurality of imaging pixels (temperature detection units) are two-dimensionally arranged.

  Thus, the thermal detector detects a temperature change caused by infrared rays incident on the thermal detector. The infrared rays emitted from the subject are imaged by being imaged on the surface of the thermal detector using an optical system. However, infrared rays (hereinafter referred to as “disturbance infrared rays”) that are emitted (radiated) from an object other than the subject toward the image sensor and do not pass through the optical system also enter the thermal detector. Examples of the object other than the subject include a lens barrel and a detector package. Here, infrared rays from the subject and disturbance infrared rays from other than the subject cannot be distinguished by the thermal detector. For this reason, there has been a problem that the subject cannot be imaged correctly due to the influence of disturbance infrared rays.

  In order to solve such a problem, for example, a conventional apparatus as shown in Patent Document 1 uses a configuration for blocking disturbance infrared rays. FIG. 12 is a conceptual diagram showing an incident infrared ray from an optical system and an incident state on an imaging pixel in a conventional apparatus. In FIG. 12, the imaging element 201 is disposed so as to face the optical system opening surface 211 whose surface is the opening surface of the optical system 210 at an interval. A plurality of imaging pixels 202 arranged in an array are provided on the surface of the imaging element 201 (upper surface in FIG. 12). Infrared rays 212 from the optical system 210 are incident on the imaging pixel 202.

  Further, on the surface of the imaging element 201, a microshield 203 is provided upright so as to partition between the imaging pixels 202 adjacent to each other among the plurality of imaging pixels 202. Furthermore, an electronic cooling element 204 is provided on the surface of the image sensor 201 (the lower surface in FIG. 12) to suppress a temperature rise due to the incidence of infrared rays on the image sensor 201 including the microshield 203. In the conventional apparatus as shown in FIG. 12, a part of disturbance infrared rays is blocked by the microshield 203.

JP 2007-127696 A

  However, the conventional apparatus as shown in FIG. 12 has the following problems. In the conventional apparatus as shown in FIG. 12, a plurality of imaging pixels 202 are arranged one-dimensionally or two-dimensionally, and a line connecting the imaging pixel 202 and the optical system opening surface 211 is determined depending on the position of the imaging pixel 202. The direction is different.

  For this reason, in the imaging pixel 202 disposed at a position away from the center of the surface on the surface of the imaging element 201, as shown in FIG. 13, a part of infrared rays 212 from the subject (infrared rays passing through the optical system) 212 A phenomenon (so-called vignetting) occurs in which 212a is blocked by hitting the upper end of the microshield 203. As a result, in the conventional apparatus, since the infrared ray 212a that should be incident is blocked by the microshield 203, the amount of incident infrared ray is reduced.

  In addition, in the imaging pixel 202 arranged at a position away from the center of the surface on the surface of the imaging element 201, infrared rays other than the infrared ray 212 collected by the optical system 210, that is, disturbance infrared rays 213 (optical system 210 to be originally blocked) There was a phenomenon in which infrared rays that did not pass through could not be blocked.

  Furthermore, in the conventional apparatus as shown in FIG. 12, the shape of the opening surface of the opening portion of the microshield 203 is a square shape in plan view. For this reason, the disturbance infrared ray 213 is incident on the corner portion of the opening surface of the opening portion of the microshield 203 in particular.

  As described above, the conventional apparatus as shown in FIG. 12 has the problem that the amount of incident infrared rays by the microshield 203 is reduced and the disturbance infrared rays 213 cannot be sufficiently blocked, resulting in image degradation. It was.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an infrared imaging device capable of more appropriately blocking disturbance infrared rays and suppressing image deterioration. .

  The infrared imaging device of the present invention is a substrate provided with a plurality of concave cavities that are disposed opposite to each other with an interval between the optical system and recessed toward the back side of the surface on the surface facing the optical system, Each of the plurality of cavities is provided with a plurality of imaging pixels for imaging a subject, and each of the plurality of imaging pixels is connected to the base material and disposed in the cavity. A support leg, a temperature detection unit disposed in the cavity through the support leg, and generating a signal corresponding to the temperature in the cavity, and a planar shape covering the opening of the cavity Provided on the base material, an imaging pixel opening for passing the infrared rays from the optical system to the temperature detection unit in the cavity is opened at a place where the infrared rays from the optical system hit the entire surface, and other than the optical system From the object to the image sensor Only the disturbance infrared ray infrared to be radiated disturbances are those having a coating surface portion to block at locations other than the image pickup pixel aperture in the entire surface.

  According to the infrared imaging device of the present invention, the imaging pixel opening is opened at a position where the infrared rays from the optical system hit the entire surface of the covering surface portion, and the covering surface portion blocks disturbance infrared rays at a location other than the imaging pixel opening on the entire surface. Therefore, disturbance infrared rays can be more appropriately blocked, and image degradation can be suppressed.

It is a top view which shows the infrared imaging device by Embodiment 1 of this invention. It is a top view which shows the imaging pixel of FIG. It is sectional drawing which follows the III-III line of FIG. It is a conceptual diagram which shows the positional relationship of an imaging pixel and an optical system. It is a top view which shows the reference pixel of FIG. It is sectional drawing which follows the VI-VI line of FIG. It is a block diagram which shows the circuit structure of the infrared imaging device of FIG. It is a top view which shows the infrared imaging device by Embodiment 2 of this invention. It is a block diagram which shows the circuit structure of the infrared imaging device of FIG. It is a block diagram which shows the circuit structure of the infrared imaging device by Embodiment 3 of this invention. It is a block diagram which shows the circuit structure of the infrared imaging device by Embodiment 4 of this invention. It is a conceptual diagram which shows the incident light from the optical system in a conventional apparatus, and the incident condition to an imaging pixel. It is a conceptual diagram which expands and shows a part of FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a plan view showing an infrared imaging device according to Embodiment 1 of the present invention.
In FIG. 1, an infrared imaging device (infrared imaging device) 100 includes a plurality of imaging pixels (normal pixels) 101 and a reference pixel 102. The plurality of imaging pixels 101 are arranged two-dimensionally (in a matrix or a lattice).

  On the surface of each of the plurality of imaging pixels 101, an imaging pixel opening 101a for allowing infrared rays from a subject to pass through the inside of the imaging pixel 101 is provided. The shape of the imaging pixel opening 101a is circular in plan view. The reference pixel 102 is disposed adjacent to the outermost imaging pixel 101 among the plurality of imaging pixels 101. A reference pixel opening 102 a is provided on the surface of the reference pixel 102. The shape of the reference pixel opening 102a is a square shape in plan view.

  Next, the structure of the imaging pixel 101 will be described. FIG. 2 is a plan view showing the imaging pixel 101 of FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a conceptual diagram showing the positional relationship between the imaging pixel 101 and the optical system 150. 2 to 4, the semiconductor substrate 1 as a base material is disposed to face the optical system 150 with an interval. The semiconductor substrate 1 is, for example, a silicon substrate.

  Further, the surface on the optical system 150 side of the semiconductor substrate 1 is provided with a plurality of concave cavities 1a that are recessed toward the back side (downward in FIG. 3) of the surface. The respective opening surfaces of the plurality of cavities 1 a are arranged so as to be parallel to the optical system opening surface 151 that is the opening surface of the optical system 150. An aluminum wiring (wiring pattern) 2 is provided on the inner wall of the cavity 1 a in the semiconductor substrate 1. A pair of support legs 3 are provided on the inner wall of the cavity 1a in the semiconductor substrate 1 so as to protrude from the inner wall of the cavity 1a toward the center of the cavity 1a.

  The support legs 3 are spaced upward from the bottom of the cavity 1a. Further, the support leg 3 has a large heat resistance and an elongated structure in order to have a heat insulating structure. A thin film metal wire 4 electrically connected to the aluminum wire 2 is formed inside the support leg 3. Connected to the support leg 3 is a temperature detection unit (temperature detection unit) 5 for converting a temperature change into an electrical signal. That is, the support leg 3 connects the temperature detection unit 5 and the semiconductor substrate 1 and supports the temperature detection unit 5 at a distance from the inner wall surface of the cavity 1a (in the hollow portion 1a). .

  The temperature detection unit 5 includes a temperature detection film (temperature detection film) 6. The temperature detection film 6 is a diode using, for example, silicon. Further, the temperature detection film 6 is electrically connected to the aluminum wiring 2 through the thin film metal wiring 4. In the temperature detection unit 5, a temperature change is caused by the incident infrared light in the cavity 1 a, and the temperature detection film 6 generates a signal corresponding to the temperature change.

  On the surface of the semiconductor substrate 1 (upper surface in FIG. 3), a shielding film 7 and a reflective film 8 are formed in a planar shape so as to cover the opening of the cavity 1a. That is, the shielding film 7 is mechanically and thermally connected to the surface of the semiconductor substrate 1 facing the optical system 150. The material of the shielding film 7 is, for example, silicon oxide. The reflective film 8 is formed so as to cover the entire surface of the shielding film 7 (upper surface in FIG. 3). The material of the reflective film 8 is a metal having a relatively high reflectivity, such as aluminum or gold.

  The shielding film 7 and the reflective film 8 form a covering surface portion. As described above, the plurality of imaging pixels 101 are formed in the plurality of cavities 1 a of the semiconductor substrate 1, respectively. Each of the plurality of imaging pixels 101 includes a support leg 3, a temperature detection unit 5, a shielding film 7, and a reflection film 8.

  Here, the imaging pixel opening 101 a is opened in the shielding film 7 and the reflection film 8. The shielding film 7 and the reflection film 8 allow only the infrared ray 152 (hereinafter referred to as “optical system passing infrared ray 152”) from the optical system 150 to pass through the temperature detection unit 5 in the cavity 1a through the imaging pixel opening 101a. On the other hand, the shielding film 7 and the reflective film 8 emit disturbance radiation that is radiated (radiated) from an object other than the subject toward the imaging pixel 101 and does not pass through the optical system 150 at a place other than the imaging pixel opening 101a on the entire surface. Block and reflect.

  Next, the configuration of the imaging pixel opening 101a will be described more specifically. As shown in FIG. 4, in the imaging pixel 101 arranged on the entire center side among the plurality of imaging pixels 101, the optical system passing infrared ray 152 enters perpendicular to the surface of the imaging pixel 101. Among the plurality of imaging pixels 101, the imaging pixel 101 arranged on the center side of the whole has an imaging pixel opening 101 a arranged at the center of the surface of the imaging pixel 101.

  On the other hand, an imaging pixel 101 (hereinafter referred to as “peripheral imaging pixel 101”) arranged out of the center of the whole of the plurality of imaging pixels 101 is not perpendicular to the surface of the peripheral imaging pixel 101 but in an oblique direction. The optical system passing infrared ray 152 enters. In the peripheral imaging pixel 101, as shown in FIGS. 1 and 4, the position of the imaging pixel aperture 101 a on the surface of the peripheral imaging pixel 101 corresponds to the incident direction of the optical system passing infrared ray 152, and the surface of the peripheral imaging pixel 101. Is off center. Further, the position of each imaging pixel aperture 101a of each of the plurality of peripheral imaging pixels 101 is different for each peripheral imaging pixel 101 corresponding to the incident direction of the optical system passing infrared ray 152.

  The size (area of the aperture surface) of the imaging pixel aperture 101a is set to correspond to the optical system passing infrared ray 152, that is, to correspond to the optical system aperture surface 151. In other words, the imaging pixel opening 101a is opened at a position where the optical system passing infrared ray 152 hits the entire surface of the shielding film 7 and the reflection film 8. Thereby, disturbance infrared rays from an object other than the optical system 150 strikes and is reflected by a portion other than the imaging pixel opening 101a in the entire surface of the reflective film 8.

  Next, the configuration of the reference pixel 102 will be described. The outline of the configuration of the reference pixel 102 is the same as that of the imaging pixel 101, and the position / size / range of the reference pixel opening 102a is different from the position / size / range of the imaging pixel opening 101a. That is, the reference pixel 102 is formed in the cavity 1 a of the semiconductor substrate 1 and has the support leg 3, the temperature detection unit 5, the shielding film 7, and the reflection film 8, similarly to the imaging pixel 101. Here, the difference from the imaging pixel 101 will be mainly described.

  FIG. 5 is a plan view showing the reference pixel 102 of FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5 and 6, the reference pixel opening 102a is disposed in the vicinity of the inner wall of the cavity 1a so as to face the support leg 3. Further, the area of the opening surface of the reference pixel opening 102a is smaller than the area of the opening surface of the imaging pixel opening 101a.

  Here, in the imaging pixel 101, the imaging pixel opening 101 a is arranged so that the optical system passing infrared ray 152 is incident on the temperature detection unit 5. On the other hand, in the reference pixel 102, the reference pixel opening 102 a is arranged so that the optical system passing infrared ray 152 does not enter the temperature detection unit 5. Thereby, only the infrared rays (hereinafter referred to as “in-pixel emission infrared rays”) emitted from the semiconductor substrate 1 and the shielding film 7 are incident on the temperature detection unit 5 of the reference pixel 102. As a result, a voltage change corresponding to the temperature of the semiconductor substrate 1 always occurs in the temperature detection film 6 of the reference pixel 102.

  Note that the reference pixel opening 102a is preferably provided for etching when the cavity 1a is formed in the semiconductor substrate 1. However, after the cavity 1a is formed in the semiconductor substrate 1, the reference pixel opening 102a may be closed. Good. Further, in this embodiment, the shape of the opening surface of the reference pixel opening 102a is a quadrangular shape in plan view, but is not limited to a quadrangular shape.

  Next, the circuit configuration of the infrared imaging device 100 will be described. FIG. 7 is a configuration diagram showing a circuit configuration of the infrared imaging device 100 of FIG. In FIG. 7, the infrared imaging device 100 is illustrated in a simplified manner as a 3 × 3 matrix pixel array, but is not limited to this number of pixels (the same applies to the second and subsequent embodiments). In FIG. 7, the plurality of diodes 21 of the pixel array are the temperature detection films 6 of the plurality of imaging pixels 101. The plurality of diodes 21 are arranged two-dimensionally (in a matrix or a lattice) so as to form a matrix.

  The anodes of the plurality of diodes 21 are made of aluminum wiring 2 and connected to a bias line 22 for applying a voltage to each row of the pixel array. The bias line 22 connects the anodes of the diodes 21 belonging to the same row among the plurality of diodes 21. To the cathodes of the plurality of diodes 21, a vertical signal line 23 made of aluminum wiring 2 for reading out a signal for each column of the pixel array is connected. The vertical signal line 23 connects the cathodes of the diodes 21 belonging to the same column among the plurality of diodes 21.

  A readout circuit 24 and one end of a switch 25 are connected in series to the vertical signal line 23 of each column. The read circuit 24 includes a sample and hold circuit 28 and a constant current source 29 that applies a constant current to the vertical signal line 23. The sample hold circuit 28 samples and stores the signal level of the imaging pixel signal which is a signal of the diode 21 appearing at both ends of the constant current source 29. A horizontal signal line 26 is connected to the other end of the switch 25 corresponding to each column of the pixel array. That is, the horizontal signal line 26 connects the other ends of the switches 25 corresponding to the respective columns of the pixel array. ON / OFF of the switch 25 is controlled by the horizontal scanning circuit 27.

  A power supply 31 is connected to the bias line 22 via a switch 30. ON / OFF of the switch 30 is controlled by the vertical scanning circuit 32. The vertical scanning circuit 32 controls ON / OFF of the switches 30 corresponding to each row of the pixel array, thereby controlling energization / cutoff of the plurality of diodes 21 in units of rows of the pixel array.

  The temperature detection film 6 of the reference pixel 102 forms a diode 33 in the circuit configuration of FIG. The anode of the diode 33 is connected to the power supply 31. A reference pixel output line 34 is connected to the cathode of the diode 33. A sample hold circuit 35 and a constant current source 36 having the same configuration as the sample hold circuit 28 and the constant current source 29 are connected to the reference pixel output line 34.

  The horizontal signal line 26 is connected to a subtractor 37 as a temperature change correction unit. The subtractor 37 is connected to the sample hold circuit 35 on the reference pixel 102 side and receives a reference pixel signal which is a signal of the sample hold circuit 35. The subtractor 37 subtracts the signal level of the reference pixel signal from the signal level of the imaging pixel signal from the horizontal signal line 26 to correct the signal level of the imaging pixel signal. Further, the subtractor 37 outputs the corrected imaging pixel signal to the output terminal 38 for external output.

  Therefore, the subtractor 37 corrects the signal level of the imaging pixel signal of the imaging pixel 101 according to the temperature of the semiconductor substrate 1 using the signal level of the reference pixel signal of the reference pixel 102. Thereby, the signal level of the imaging pixel signal output to the output terminal 38 is the signal of the imaging pixel signal of the imaging pixel 101 corresponding to the intra-pixel radiation infrared ray from the semiconductor substrate 1 and the shielding film 7 and the optical system passing infrared ray 152. This is a value obtained by subtracting the signal level of the reference pixel signal of the reference pixel 102 corresponding to the intra-pixel radiation infrared ray from the level. The corrected signal level is nothing but a value corresponding to the optical system passing infrared ray 152 from the optical system 150.

  According to the first embodiment as described above, the imaging pixel aperture 101a is opened at a location where the optical system passing infrared ray 152 from the optical system 150 hits the entire surface of the shielding film 7 and the reflecting film 8, and the shielding film 7 and the reflecting film 7 are reflected. The film 8 blocks and reflects the disturbance infrared rays at a place other than the imaging pixel opening 101a on the entire surface. With this configuration, disturbance infrared rays from other than the optical system 150 can be more appropriately blocked, and image deterioration can be suppressed.

Here, the conventional apparatus as shown in FIG. 12 requires the electronic cooling element 204 for keeping the temperature constant, which increases the size of the apparatus, increases the power consumption, and increases the manufacturing cost. There was a problem.
In contrast, in the first embodiment, the temperature of the shielding film 7 varies with the semiconductor substrate 1, but the subtractor 37 uses the signal of the reference pixel 102 to change the signal level of the imaging pixel signal of the imaging pixel 101. Correction is performed according to the temperature of the semiconductor substrate 1. With this configuration, even if the temperature of the semiconductor substrate 1 changes, the change in temperature at the signal level of the imaging pixel signal can be offset. As a result, the electronic cooling element 204 in the conventional apparatus as shown in FIG. 12 can be omitted, and the apparatus can be downsized, the power consumption can be reduced, and the manufacturing cost can be reduced.

  In the first embodiment, the reflection film 8 for reflecting disturbance infrared rays is formed on the surface of the shielding film 7. With this configuration, the temperature rise of the shielding film 7 and the semiconductor substrate 1 due to disturbance infrared rays can be suppressed.

Embodiment 2. FIG.
In the first embodiment, one reference pixel 102 is used. On the other hand, in the second embodiment, a plurality of reference pixels 102 are used. FIG. 8 is a plan view showing an infrared imaging device according to Embodiment 2 of the present invention. FIG. 9 is a configuration diagram showing a circuit configuration of the infrared imaging device 100 of FIG. The outline of the configuration of the infrared imaging apparatus 100 of the second embodiment is the same as that of the first embodiment, and the number of reference pixels 102 and the electric circuit around the reference pixel 102 are different from those of the first embodiment. . Here, the difference from Embodiment 1 will be mainly described.

  8 and 9, the plurality of reference pixels 102 of Embodiment 2 are arranged one-dimensionally in the column direction in the pixel array. The anodes of the diodes 33 of the plurality of reference pixels 102 are connected to the bias line 22. The cathodes of the diodes 33 of the plurality of reference pixels 102 are connected to the vertical signal line 23.

  Further, a switch 39 is interposed in the signal line between the subtractor 37 and the sample hold circuit 35 of the second embodiment. ON / OFF of the switch 39 is controlled by the horizontal scanning circuit 27. Further, the vertical scanning circuit 32 energizes the diodes 33 of the reference pixels 102 belonging to the same row as the diodes 21 of the imaging pixels 101 that are energized in the pixel array.

  Therefore, the subtractor 37 according to the second embodiment corrects the signal level of the imaging pixel signal using the signal level of the reference pixel signal of the reference pixel 102 that belongs to the same row as the diode 21 of the imaging pixel 101 that is energized in the pixel array. To do. Other configurations are the same as those in the first embodiment.

  According to the second embodiment as described above, the same effects as those of the first embodiment can be obtained even in a configuration using a plurality of reference pixels 102. At the same time, the subtractor 37 corrects the signal level of the imaging pixel signal using the signal level of the reference pixel signal of the reference pixel 102 belonging to the same row as the diode 21 of the imaging pixel 101 that is energized in the pixel array. With this configuration, when there is a temperature difference of the semiconductor substrate 1 in the column direction in the pixel array, the temperature difference can be dealt with, and the accuracy of correcting the signal level of the imaging pixel signal can be further improved.

Embodiment 3 FIG.
In the first and second embodiments, the configuration using the subtractor 37 as the temperature change correction unit has been described. On the other hand, in the third embodiment, a configuration in which the correction circuit 40 is used as the temperature change correction unit will be described.

  FIG. 10 is a block diagram showing a circuit configuration of an infrared imaging device according to Embodiment 3 of the present invention. In FIG. 10, the outline of the configuration of the infrared imaging apparatus 100 of the third embodiment is the same as that of the second embodiment. The subtracter 37 is deleted and the correction circuit 40 is connected to the output terminal 38. Different from 2. Here, the difference from Embodiment 2 will be mainly described.

  In FIG. 10, the correction circuit 40 includes an A / D conversion unit and a memory (storage unit) (none of which is shown). The correction circuit 40 receives the imaging pixel signal and the reference pixel signal from the output terminal 38. The signal levels of the imaging pixel signal and the reference pixel signal received by the correction circuit 40 are A / D converted by the A / D conversion unit and stored in the memory as digital data.

  Further, the correction circuit 40 stores the signal level of the reference pixel signal of the reference pixel 102 in the memory for each row in accordance with the readout timing of the reference pixel 102, and the signal of the reference pixel signal of the reference pixel 102 for each stored row. The imaging pixel signal is corrected by subtracting the level from the signal level of the imaging pixel signal of the imaging pixel 101 belonging to the same row.

  Thereby, the signal level of the output signal of the correction circuit 40 becomes a value obtained by subtracting the output due to the temperature of the semiconductor substrate 1 from the signal level of the imaging pixel signal of each imaging pixel 101, and the signal level of the output signal of the correction circuit 40 is This is nothing but the value according to the optical system passing infrared ray 152. For example, it may be stored in a sample hold circuit or the like instead of the memory. Other configurations are the same as those in the second embodiment.

  According to the third embodiment as described above, even when the correction circuit 40 is used as the temperature change correction unit instead of the subtractor 37, the same effect as that of the second embodiment can be obtained.

  In the second and third embodiments, the reference pixels 102 are arranged one-dimensionally in the column direction in the pixel array. However, the present invention is not limited to this example, and the reference pixels 102 may be arranged one-dimensionally in the row direction in the pixel array. Further, the reference pixels 102 may be arranged two-dimensionally in both the row direction and the column direction in the pixel array.

Embodiment 4 FIG.
In the first to third embodiments, the configuration in which the signal level of the imaging pixel signal is corrected using the signal level of the reference pixel signal has been described. On the other hand, in the fourth embodiment, a configuration for correcting the signal level of the imaging pixel signal using the output signal of the temperature sensor 50 will be described.

  FIG. 11 is a block diagram showing a circuit configuration of an infrared imaging device according to Embodiment 4 of the present invention. In FIG. 11, the outline of the configuration of the infrared imaging apparatus 100 of the fourth embodiment is the same as that of the first embodiment. The reference pixel 102 and the subtracter 37 are deleted, and a temperature sensor (temperature The difference from the first embodiment is that a monitor) 50 and a correction processing unit 60 as a temperature change correction unit are added. Here, the difference from Embodiment 1 will be mainly described.

  The temperature sensor 50 is thermally connected to the semiconductor substrate 1. Here, the temperature sensor 50 may be provided inside the semiconductor substrate 1 or may be mechanically connected to the surface of the semiconductor substrate 1. Further, for example, a metal film whose resistance value changes with temperature, a diode, or the like may be used for the temperature sensor 50, or a sensor having the same configuration as the temperature detection film 6 may be used.

  The correction processing unit 60 is connected to the output terminal 38 of the pixel array and the output terminal 51 of the temperature sensor 50. The correction processing unit 60 monitors the output of the temperature sensor 50 and obtains the temperature (element temperature) of the semiconductor substrate 1, and the correction data calculation unit 62 acquires (calculates) the pixel output corresponding to the element temperature. And a subtractor 63.

  The correction data calculation unit 62 associates the temperature of the semiconductor substrate 1 and the signal level (pre-registered signal level) of the imaging pixel signal of the imaging pixel 101 at that temperature, and stores them in advance as temperature correspondence output information. Yes. Here, the imaging pixel 101 outputs an electrical signal corresponding to the temperature change of the temperature detection unit 5 generated by the incidence of infrared rays, and is emitted from the semiconductor substrate 1 and the shielding film 7 and enters the temperature detection unit 5. If the amount of infrared radiation in the pixel to be emitted is known, the amount of change in the temperature of the temperature detection unit 5 corresponding to the amount of infrared radiation, that is, the signal level of the imaging pixel signal of the imaging pixel 101 is obtained in advance by calculation or testing. be able to.

  That is, if the infrared light incident on the imaging pixel 101 is the intra-pixel radiation infrared radiation emitted from the semiconductor substrate 1 and the shielding film 7, the temperature of the semiconductor substrate 1 is monitored, and the temperature of the semiconductor substrate 1 is used. It is possible to acquire (calculate) the signal level of the imaging pixel signal of the imaging pixel 101 corresponding to the in-pixel radiation infrared rays. Therefore, the correction data calculation unit 62 acquires the signal level of the imaging pixel signal corresponding to the temperature of the semiconductor substrate 1 based on the temperature-corresponding output information.

  The subtracter 63 subtracts the signal level of the imaging pixel signal corresponding to the temperature of the semiconductor substrate 1 acquired by the correction data calculation unit 62 from the signal level of the imaging pixel signal received from the horizontal signal line 26, thereby obtaining the horizontal signal line. The signal level of the imaging pixel signal received from H.26 is corrected. The signal level of the image pickup pixel signal after the correction is nothing but a value corresponding to the optical system passing infrared ray 152 from the optical system 150.

  The correction processing unit 60 can be configured by a computer (not shown) having an arithmetic processing unit (CPU), a storage unit, and a signal input / output unit. Programs for realizing the functions of the temperature processing unit 61 and the correction data calculating unit 62 are stored in the storage unit of the computer of the correction processing unit 60. Other configurations are the same as those in the first embodiment.

  According to the fourth embodiment as described above, even if the reference pixel 102 is omitted, even if the temperature of the semiconductor substrate 1 changes, the change in temperature in the signal level of the imaging pixel signal is canceled out. And the same effects as those of the first embodiment can be obtained.

  In the first to fourth embodiments, the configuration using the diode as the temperature detection unit has been described. However, the present invention is not limited to this example, and a bolometer (resistance) may be used as the temperature detection unit. In this case, in the first to fourth embodiments, the readout circuit 24, the sample hold circuit 28, and the constant current source 29 used together with the diode 21 can be omitted.

  Moreover, in Embodiment 1-4, the structure which used both the shielding film 7 and the reflecting film 8 as a coating | coated surface part was demonstrated. However, the present invention is not limited to this example, and the reflection film 8 may be omitted and only the shielding film 7 may be used as the covering surface portion.

  Furthermore, in Embodiments 1 to 4, the example in which the array of the imaging pixels 101 is a two-dimensional array has been described. However, the pixel array of the plurality of imaging pixels 101 may be a one-dimensional array, or the pixel array may be arranged in a shape other than a lattice shape.

  The functions of the horizontal scanning circuit 27, the vertical scanning circuit 32, and the correction circuit 40 in Embodiments 1 to 4 are the same as those of a computer having an arithmetic processing unit (CPU), a storage unit, and a signal input / output unit. You may implement | achieve by arithmetic processing.

  Further, in the first to fourth embodiments, the respective opening surfaces of the plurality of cavities 1 a are arranged so as to be parallel to the optical system opening surface 151 that is the opening surface of the optical system 150. However, the present invention is not limited to this example, and the respective opening surfaces of the plurality of cavities 1 a may be arranged to be inclined with respect to the optical system opening surface 151.

  DESCRIPTION OF SYMBOLS 1 Semiconductor substrate (base material), 1a Cavity part, 3 Support leg, 5 Temperature detection part, 7 Shielding film, 37 Subtractor (temperature change correction part), 40 Correction circuit (temperature change correction part), 50 Temperature sensor (base) Material temperature detection means), 60 correction processing unit (temperature change correction unit), 100 infrared imaging device, 101 imaging pixel, 101a imaging pixel aperture, 102 reference pixel, 150 optical system.

Claims (7)

A base material provided with a plurality of concave cavities which are disposed opposite to each other with an interval between the optical system and are recessed toward the back side of the surface on the surface facing the optical system;
An infrared imaging device that is disposed in each of the plurality of cavities and includes a plurality of imaging pixels for imaging a subject,
Each of the plurality of imaging pixels is
A support leg connected to the substrate and disposed in the cavity;
A temperature detection unit disposed in the cavity through the support leg and generating a signal corresponding to the temperature in the cavity;
In order to pass the infrared rays from the optical system to the temperature detection unit in the cavity portion where the infrared rays from the optical system hit the entire surface of the base material so as to cover the opening of the cavity portion. And a covering surface portion that blocks disturbance infrared rays, which are infrared rays that are radiated from an object other than the optical system toward the imaging element and become disturbances, at portions other than the imaging pixel opening in the entire surface. An infrared imaging device. The temperature change correction part which receives the imaging pixel signal which is a signal from the said temperature detection part, and correct | amends the signal level of the said imaging pixel signal according to the temperature of the said base material is characterized by the above-mentioned. Infrared imaging device. A reference pixel that is formed on the base material and generates a reference pixel signal that is a signal corresponding to a temperature of the base material;
The infrared ray according to claim 2, wherein the temperature change correction unit receives the reference pixel signal from the reference pixel and corrects the signal level of the imaging pixel signal using a signal level of the reference pixel signal. Imaging device. A plurality of the reference pixels are formed on the substrate;
The infrared imaging device according to claim 3, wherein the temperature change correction unit corrects the signal level of the imaging pixel signal using a signal level of the reference pixel signal of the plurality of reference pixels. The plurality of imaging pixels are arranged two-dimensionally so as to form a pixel array represented by a matrix,
The plurality of reference pixels are arranged one-dimensionally or two-dimensionally so as to belong to a row or a column in the pixel array,
When the signal level of the imaging pixel signal is corrected, the temperature change correction unit uses the signal level of the reference pixel signal of the reference image belonging to the same row or column to which the imaging pixel belongs. The infrared imaging device according to claim 4, wherein a signal level of the imaging pixel signal is corrected. A substrate temperature detecting means that is thermally connected to the substrate and generates a signal corresponding to the temperature of the substrate;
The temperature change correction unit is
Monitoring the temperature of the substrate through the substrate temperature detecting means;
The temperature of the base material and the pre-registration signal level that is the signal level of the imaging pixel signal at that temperature are associated with each other and stored in advance as temperature-corresponding output information,
Obtaining the pre-registration signal level corresponding to the temperature of the base material being monitored based on the temperature corresponding output information;
The infrared imaging device according to claim 2, wherein the signal level of the imaging pixel signal received from the imaging pixel is corrected using the acquired pre-registered signal level. The covering surface portion is
A shielding film for shielding the disturbance infrared rays, provided to cover the cavity on the optical system side surface of the substrate;
The infrared imaging according to any one of claims 1 to 6, further comprising: a reflection film provided on a surface of the shielding film on the optical system side for reflecting the disturbance infrared rays. apparatus.

Images