JP2015190897A - infrared sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared sensor which is compact, yet can measure an incident infrared ray with higher accuracy.SOLUTION: An infrared sensor according to the present invention is characterized by having: a quantum type infrared sensor element for outputting a signal that corresponds to an incident infrared ray; a resin package having an opening in the top face, the opening optically connecting the infrared sensor element, which optically connects to the outside via the opening, and the outside; an optical shutter unit disposed inside the opening, joined to the infrared sensor element directly or indirectly via metal, and capable of switching an infrared transmission rate; and a control unit, connected to the optical shutter unit, for controlling the infrared transmission rate of the optical shutter unit on the basis of a control signal.

Description

  The present invention relates to an infrared sensor device, and more particularly to an infrared sensor device provided with an optical shutter.

  Quantum type infrared sensors are sensitive to infrared rays below the wavelength corresponding to the band gap energy of semiconductors, and it is known that an electromotive force is generated when infrared rays having a specific wavelength range having sensitivity are incident. Yes. When such an infrared sensor is used as a human sensor at room temperature, a current corresponding to the difference between the temperature of the infrared sensor itself and the human body temperature sensed by the infrared sensor is output.

  Quantum infrared sensors are susceptible to noise such as ambient thermal noise, so when measuring the temperature of an object from the amount of infrared energy using a quantum infrared sensor, measure the signal obtained from the sensor. Various methods are known for correcting according to the ambient temperature around the sensor at the time (for example, Patent Document 1).

  Patent Document 1 discloses that an infrared ray is incident on an infrared sensor element by opening and closing the shutter by providing a shutter that can be physically opened and opened between the infrared lens and the quantum infrared sensor element. The noise detected when the infrared rays are not incident on the infrared sensor element is canceled. The infrared sensor described in Patent Document 1 can measure the correct temperature without using a dedicated reference heat source.

Japanese Unexamined Patent Publication No. 2000-131149

  However, in the conventional infrared sensor device with a shutter described in Patent Document 1, the infrared sensor element receives even infrared rays emitted from the shutter itself. Therefore, when the temperatures of the shutter and the infrared sensor element are different, the output of the infrared sensor element is affected by the infrared rays radiated from the shutter, so that the accurate temperature of the object cannot be measured. There was a problem.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an infrared sensor that can measure incident infrared rays with high accuracy while being small in size.

  Specifically, the infrared sensor of the first aspect of the present invention is a quantum type infrared sensor element that outputs a signal corresponding to incident infrared rays, and a resin package having an opening formed on the upper surface thereof, The opening is optically connected to the outside through the opening, the infrared sensor element is optically connected to the outside, a resin package, and the infrared sensor element is disposed in the opening. An optical shutter unit that is directly or indirectly joined via metal and is capable of switching infrared transmittance, and is connected to the optical shutter unit, and controls the infrared transmittance of the optical shutter unit based on a control signal. And a control unit.

  The infrared sensor according to the second aspect of the present invention is the infrared sensor according to the first aspect, wherein the control unit controls the infrared transmittance of the optical shutter unit to a low state. It further has a calculation part which generates a correction signal which makes an output of an infrared sensor element zero.

  An infrared sensor according to a third aspect of the present invention is the infrared sensor according to the first aspect or the second aspect, wherein the optical shutter portion covers the entire visual field of the infrared sensor element. To do.

  Although the infrared sensor device of the present invention is small, it can measure incident infrared rays with higher accuracy.

It is a cross-sectional schematic diagram which shows the structural example of the infrared sensor apparatus concerning the 1st Embodiment of this invention. It is a cross-sectional schematic diagram which shows the structural example of the infrared sensor apparatus concerning the 2nd Embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view showing a configuration example of an infrared sensor 100 according to the first embodiment of the present invention. The infrared sensor 100 includes an infrared sensor element 110, a resin package 120 in which an opening 121 is formed, an optical shutter unit 130 that switches the transmittance of infrared light incident on the infrared sensor element 110, and the infrared transmittance of the optical shutter 130. The control part 140 to control and the calculating part 150 which produces | generates the correction signal which makes the output from the infrared sensor element 110 zero are provided.

  The infrared sensor 110 is a quantum infrared sensor element that outputs an electrical signal corresponding to incident infrared rays. An opening 121 is formed on the upper surface of the resin package 120, and the infrared sensor element 110 optically connected to the outside is provided in the opening 121.

  The optical shutter unit 130 is disposed in the opening 121 of the resin package 120 and is directly joined to the infrared sensor element 110. The optical shutter unit 130 can switch the transmittance of infrared rays incident on the infrared sensor element 110 by opening and closing the shutter, for example. In the present embodiment, the optical shutter unit 130 is disposed so as to cover the entire opening 121, but may be disposed so as to cover only a part of the opening 121. It is preferable that the optical shutter unit 130 covers the entire visual field of the infrared sensor element 110.

  The control unit 140 controls the infrared transmittance of the optical shutter unit 130. The control unit 140 is connected to the optical shutter unit 130, and outputs a control signal based on the output of the infrared sensor element 110 to control the infrared transmittance of the optical shutter unit 130. Switch. Here, examples of the optical shutter capable of switching the infrared transmittance according to the control signal include a shutter using an interference filter capable of switching the transmittance by changing the relative position of the multilayer film by applying a voltage. It is done.

  The control unit 140 opens and closes the shutter of the optical shutter unit 130 to generate a state where infrared light is incident on the infrared sensor element 110 and a state where infrared light is not incident on the infrared sensor element 110. . Therefore, the optical shutter unit 130 needs to be controllable between a first state with a low infrared transmittance and a second state with a high infrared transmittance. It is preferable that the optical shutter unit 130 can control the infrared transmittance as a first state having a low infrared transmittance to 10% or less, preferably 5% or less, more preferably 1% or less. Further, as the second state having a high infrared transmittance, it is preferable that the infrared transmittance can be controlled to 90% or more, preferably 95% or more, more preferably 99% or more.

  The calculation unit 150 is connected to the infrared sensor element 110 and the control unit 140, and receives an output signal from the infrared sensor element 110 and a control signal from the control unit 140. Here, when the control unit 140 controls the optical shutter unit 130 to a state where the infrared transmittance is low (the above-described first state), the calculation unit 150 corrects the output from the infrared sensor element 110 to zero. Is generated.

  When the optical shutter unit 130 is controlled to the first state, the infrared light incident on the infrared sensor element 110 from the outside is substantially blocked, so that the infrared light incident on the infrared sensor element 110 is the optical shutter unit. Only infrared rays due to the temperature of 130 are obtained. Here, in the infrared sensor 100, since the infrared sensor element 110 and the optical shutter part 130 are directly joined, the infrared sensor element 110 and the optical shutter part 130 are in a thermally balanced state. Accordingly, there is no temperature difference between the infrared sensor element 110 and the optical shutter unit 130, and the output of the infrared sensor element 110 is not affected by the optical shutter unit 130.

  Therefore, when the optical shutter unit 130 is controlled to have a low infrared transmittance, the output of the infrared sensor element 110 is theoretically zero. However, since the infrared sensor element 110 further outputs signals caused by various noises such as ambient thermal noise, electromagnetic noise, and offset by IC in addition to infrared rays from an object in the field of view, the output of the infrared sensor element 110 Will never be zero. At this time, the calculation unit 150 generates a correction signal that makes the output of the infrared sensor element 110 zero, so that signals caused by various noises can be canceled.

  Even when the arithmetic unit 150 corrects the signal from the infrared sensor element 110 to control the optical shutter unit 130 to a state where the infrared transmittance is high (the second state described above), the infrared sensor element 110 Signals caused by various noises can be canceled from the output.

  In the infrared sensor 100, since the infrared sensor element 110 and the optical shutter unit 130 are in a thermal equilibrium state, the output of the infrared sensor element 110 is not affected by the optical shutter unit 130. Therefore, since it is not necessary to cancel a signal due to thermal noise from the optical shutter unit 130, it is possible to measure infrared rays with higher accuracy than a conventional infrared sensor with a shutter.

[Second Embodiment]
FIG. 2 is a schematic cross-sectional view showing a configuration example of an infrared sensor 200 according to the second embodiment of the present invention. The infrared sensor 200 includes an infrared sensor element 210, a resin package 220 having an opening 221 formed therein, a metal 225 connected to the infrared sensor element 210, and an optical shutter that switches the transmittance of infrared rays incident on the infrared sensor element 210. Unit 230 and a control unit 240 that generates a correction signal for making the output from the infrared sensor element 210 zero.

  The infrared sensor 210 is a quantum infrared sensor element that outputs an electrical signal corresponding to incident infrared rays. An opening 221 is formed on the upper surface of the resin package 220, and the opening 221 optically connects the infrared sensor element 210 provided on the bottom of the opening to the outside.

  The optical shutter 230 is disposed in the opening 221 of the resin package 220 and is indirectly joined to the infrared sensor element 210 via the metal 225. The optical shutter unit 230 can switch the transmittance of infrared rays incident on the infrared sensor element 210.

  The metal 225 is preferably a metal having high thermal conductivity, and specific examples include copper, aluminum, and stainless steel.

  The control unit 240 controls the infrared transmittance of the optical shutter unit 230 and is connected to the optical shutter unit 230 and outputs a control signal to switch the infrared transmittance of the optical shutter unit 230.

  The calculation unit 250 is connected to the infrared sensor element 210 and the control unit 240, and receives an output signal from the infrared sensor element 210 and a control signal from the control unit 240. Here, when the control unit 240 controls the optical shutter unit 230 to a state where the infrared transmittance is low (the first state described above), the calculation unit 250 corrects the output from the infrared sensor element 210 to zero. Is generated.

  In the infrared sensor 200, the infrared sensor element 210 and the optical shutter unit 230 are indirectly joined via the metal 225. However, since the metal 225 is a member having high thermal conductivity, the infrared sensor element 210 and the optical shutter. The unit 230 is in thermal equilibrium. Accordingly, there is no temperature difference between the infrared sensor element 210 and the optical shutter unit 230, and the output of the infrared sensor element 210 is not affected by the optical shutter unit 230. Therefore, since it is not necessary to cancel a signal due to thermal noise from the optical shutter unit 230, it is possible to measure infrared rays with higher accuracy than a conventional infrared sensor with a shutter.

  The present invention is suitable as an infrared sensor device used for object detection and a temperature sensor.

100, 200 Infrared sensor device 110, 210 Infrared sensor element 120, 220 Structure 121, 221 Opening part 130, 230 Optical shutter part 140, 240 Control part 225 Spacer 150, 250 Calculation part

Claims (3)

A quantum-type infrared sensor element that outputs a signal corresponding to incident infrared rays;
A resin package having an opening formed on an upper surface thereof, wherein the opening is optically connected to the outside through the opening, and the infrared sensor element and the outside are optically connected. Package and
An optical shutter unit disposed in the opening, directly or indirectly joined to the infrared sensor element via a metal, and capable of switching infrared transmittance;
An infrared sensor comprising: a control unit connected to the optical shutter unit and controlling an infrared transmittance of the optical shutter unit based on a control signal.   The control unit may further include a calculation unit that generates a correction signal that makes the output of the infrared sensor element zero when the control unit controls the infrared transmittance of the optical shutter unit to a low state. Item 15. The infrared sensor according to Item 1.   The infrared sensor according to claim 1, wherein the optical shutter portion covers the entire visual field of the infrared sensor element.

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