Infrared radiation detecting device

• US 20030133489A1
• Filed: 12/10/2002
• Published: 07/17/2003
• Est. Priority Date: 01/17/2002
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Hirota, Masaki, Nakajima, Yasushi
• Granted Patent: US 6,781,128 B2
• Time in Patent Office: Days
• US Class Current: 374/121
• CPC Class Codes: G01J 5/08 Optical arrangements
• CPC Class Codes: G01J 5/0853 having infrared absorbers other than the usual absorber layers deposited on infrared detectors like bolometers, wherein the heat propagation between the absorber and the detecting element occurs within a solid
• CPC Class Codes: G01J 5/10 using electric radiation detectors
• CPC Class Codes: G01J 5/12 using thermoelectric elements, e.g. thermocouples

Abstract

An infrared radiation detecting device is constructed using a manufacturing method to increase the infrared radiation absorptance of the infrared radiation absorbing film. The infrared radiation detecting device has an infrared radiation absorbing film. In one embodiment, the infrared radiation absorbing film has a varying film thickness. The film thickness difference between the thickest points and the thinnest points and the spacing between the thickest points within the same plane are set to decrease the effective surface reflectance cause by the interference or scattering effects of the infrared radiation. Preferably, the film thickness differences between the thickest points and the thinnest points are equal to or greater than ¼ of the wavelength of the infrared radiation being measured, and the spacing between the thickest points within the same plane is shorter than the wavelength of the infrared radiation being measured.

Claims

1. An infrared radiation detecting element comprising:

an infrared radiation absorbing film constructed to convert incident infrared radiation with an intensity and a predetermined wavelength into thermal energy, and detect the intensity of the incident infrared radiation,

the infrared radiation absorbing film including an infrared radiation incident surface with a plurality of first surface areas having first refractive indices arranged in a predetermined pattern relative to a plurality of second surface areas having second refractive indices that are different from the first refractive indices of the first surface areas,

the first and second surface areas of the infrared radiation absorbing film being configured and arranged in the predetermined pattern to increase infrared radiation absorptance of the infrared radiation absorbing film.

2. The infrared radiation detecting element as recited in claim 1, wherein

the infrared radiation absorbing film further includes an infrared radiation emission surface spaced from the infrared radiation incident surface,

the first surface areas are formed by a plurality of thick points having first film thicknesses as measured in a transverse direction between the infrared radiation incident surface and the infrared radiation emission surface,

the second surface areas are formed by a plurality of thin points having second film thicknesses as measured between the infrared radiation incident surface and the infrared radiation emission surface, and

the thick and thin points being configured and arranged such that a predetermined film thickness difference is formed by a relative height difference between the thick and thin points and a predetermined spacing within a plane is formed between the thick points, the predetermined spacing and the predetermined film thickness difference are set to decrease effective surface reflectance due to interference or scattering of the incident infrared radiation striking the infrared radiation incident surface.

3. The infrared radiation detecting element as recited in claim 2, wherein

the film thickness difference between the thick and thin points is at least equal to about ¼

of the predetermined wavelength of the incident infrared radiation being detected; and

the predetermined spacing between the thick points within a plane is shorter than the predetermined wavelength of the incident infrared radiation being detected.

4. The infrared radiation detecting element as recited in claim 2, wherein

the infrared radiation absorbing film has a non-uniform refractive index between the infrared radiation incident surface and the infrared radiation emission surface, the non-uniform refractive index varying in a continuous manner between the infrared radiation incident surface and the infrared radiation emission surface;

and

the infrared radiation incident surface of the infrared radiation absorbing film has a refractive index that is lower than a refractive index of the infrared radiation emission surface of the infrared radiation absorbing film.

5. The infrared radiation detecting element as recited in claim 2, wherein

the infrared radiation absorbing film is a multi-layered structure having a plurality of layers with different refractive indices to form a non-uniform refractive index the transverse direction extending between the infrared radiation incident surface and the infrared radiation emission surface;

and

the infrared radiation incident surface of the infrared radiation absorbing film has a refractive index that is lower than a refractive index of the infrared radiation emission surface of the infrared radiation absorbing film.

6. The infrared radiation detecting element as recited in claim 1, wherein

the infrared radiation incident surface is uneven to form a three dimensional surface.

7. The infrared radiation detecting element as recited in claim 1, wherein

the infrared radiation incident surface is a substantially flat planar surface.

8. The infrared radiation detecting element as recited in claim 7, wherein

the predetermined pattern of the first and second surface areas form substantially parallel lines of the first surface areas that alternate with substantially parallel lines of the second surface areas.

9. The infrared radiation detecting element as recited in claim 7, wherein

the predetermined pattern of the first and second surface areas form a substantially checkerboard of the first and second surface areas alternating relative to each other.

10. The infrared radiation detecting element as recited in claim 1, wherein

the infrared radiation absorbing film overlies a substrate with a cavity such that the infrared radiation absorbing film is suspended above the cavity;

and

the infrared radiation absorbing film is formed above at least one cantilever beam with at least one thermopile having first and second spaced ends such that the infrared radiation absorbing film is supported by the second end of the cantilever beam to form a hot junction, the first end being connected to the substrate to form a cold junction with a predetermined distance being formed between the second end and the substrate.

11. An infrared radiation detecting element comprising:

an infrared radiation absorbing film constructed to convert incident infrared radiation with an intensity and a predetermined wavelength into thermal energy, and detect the intensity of the incident infrared radiation,

the infrared radiation absorbing film having a plurality of thick points with first film thicknesses arranged in a predetermined pattern relative to a plurality of thin points with second film thicknesses,

the thick and thin points being configured and arranged such that a predetermined film thickness difference is formed between the thick and thin points and a predetermined spacing within a plane is formed between the thick points,

the predetermined spacing and the predetermined film thickness difference are arranged and configured to decrease effective surface reflectance due to interference or scattering of the incident infrared radiation striking the infrared radiation absorbing film.

12. The infrared radiation detecting element as recited in claim 11, wherein

the film thickness difference between the thick and thin points is at least equal to about ¼

of the predetermined wavelength of the incident infrared radiation being detected; and

the predetermined spacing between the thick points within a plane is shorter than the predetermined wavelength of the incident infrared radiation being detected.

13. The infrared radiation detecting element as recited in claim 11, wherein

the infrared radiation absorbing film has a non-uniform refractive index between an infrared radiation incident surface and an infrared radiation emission surface, the non-uniform refractive index varying in a continuous manner between the infrared radiation incident surface and the infrared radiation emission surface;

and

the infrared radiation incident surface of the infrared radiation absorbing film has a refractive index that is lower than a refractive index of the infrared radiation emission surface of the infrared radiation absorbing film.

14. The infrared radiation detecting element as recited in claim 11, wherein

the infrared radiation absorbing film is a multi-layered structure having a plurality of layers with different refractive indices to form a non-uniform refractive index the transverse direction extending between an infrared radiation incident surface and an infrared radiation emission surface;

and

the infrared radiation incident surface of the infrared radiation absorbing film has a refractive index that is lower than a refractive index of the infrared radiation emission surface of the infrared radiation absorbing film.

15. The infrared radiation detecting element as recited in claim 11, wherein

the infrared radiation absorbing film overlies a substrate with a cavity such that the infrared radiation absorbing film is suspended above the cavity;

and

the infrared radiation absorbing film is formed above at least one cantilever beam with at least one thermopile having first and second spaced ends such that the infrared radiation absorbing film is supported by the second end of the cantilever beam to form a hot junction, the first end being connected to the substrate to form a cold junction with a predetermined distance being formed between the second end and the substrate.

16. An infrared radiation detecting device comprising:

an array sensor including a plurality of sensor elements in which an infrared radiation absorbing film is formed,

the infrared radiation absorbing film being formed in a predetermined detecting region having a predetermined detecting shape that corresponds to an image shape of an object to be detected.

17. A method of manufacturing an infrared radiation detecting element comprising:

mixing an infrared radiation absorbing substance with a liquid carrier material having a prescribed viscosity together to form a discharge material;

filling a pressure chamber having a discharge opening with the discharge material;

discharging the discharge material at least two times from the discharge opening by adjusting pressure inside the pressure chamber to deposit the discharge material on a prescribed infrared radiation absorbing film formation region of the infrared radiation detecting device so as to form an infrared radiation absorbing film having a non-uniform film thickness distribution; and

removing the liquid carrier material from the discharge material deposited on the prescribed infrared radiation absorbing film formation region of the infrared radiation detecting device.

18. The method of manufacturing as recited in claim 17, further comprising

redistributing the discharge material prior to the removing of the liquid carrier material from the discharge material to form a concentration distribution of the infrared radiation absorbing substance in the discharge material such that a refractive index is formed on a side of the infrared radiation absorbing film where infrared radiation is incident is lower than a refractive index formed on a side of the infrared radiation absorbing film where infrared radiation is emitted.

19. The method of manufacturing as recited in claim 18, wherein

the redistributing of the discharge material is performed by applying at least one of gravitational force, electrostatic force, and magnetic force to the infrared radiation absorbing substance in the discharge material to form the concentration distribution.

20. The method of manufacturing as recited in claim 17, wherein

the removing of the liquid carrier material from the discharge material is performed by subjecting the discharge material to at least one of heat and light irradiation.

21. The method of manufacturing as recited in claim 17, wherein

the discharging of the discharge material is performed to form an array sensor having a plurality of an infrared radiation absorbing film regions, the infrared radiation absorbing film regions being formed by

first discharging a first quantity of the discharge material in a first infrared radiation absorbing film formation region,

second discharging a second quantity of the discharge material in an adjacent second infrared radiation absorbing film formation region while the first quantity of the discharge material deposited in the first infrared radiation absorbing film formation region is drying and curing, and

third discharging a third quantity of the discharge material in the first infrared radiation absorbing film formation region while the second quantity of the discharge material deposited in the second infrared radiation absorbing film formation region is drying and curing.

22. The method of manufacturing as recited in claim 17, wherein

the discharging of the discharge material is performed to form an array sensor having a plurality of infrared radiation absorbing film regions, and further comprising

subsequently conducting a pixel sensitivity inspection of the infrared radiation absorbing film regions to locate low-sensitivity pixels, and then discharging an additional quantity of a discharge material obtained by mixing an infrared radiation absorbing substance with a liquid carrier material having a prescribed viscosity is added to low-sensitivity pixels.

23. The method of manufacturing as recited in claim 17, wherein

the mixing of the discharge material is performed by

mixing together a first infrared radiation absorbing substance and a first liquid carrier material having a first prescribed viscosity to form a first discharge material portion, and

mixing together a second infrared radiation absorbing substance having a smaller refractive index than the first infrared radiation absorbing substance and a second liquid carrier material having a second prescribed viscosity to form a second discharge material portion;

the filling of the pressure chamber with the discharge material is performed by

filling a first pressure chamber section having a first discharge opening with the first discharge material portion, and

a second pressure chamber section having a second discharge opening with the second discharge material portion;

the discharging of the discharge material is performed by

first discharging the first discharge material portion from the first discharge opening by adjusting the pressure inside the first pressure chamber to deposit on the prescribed infrared radiation absorbing film formation region, and

second discharging the second discharge material portion from the second discharge opening by adjusting the pressure inside the second pressure chamber to deposit on the prescribed infrared radiation absorbing film formation region; and

the removing of the liquid carrier material is performed by

first removing the first liquid carrier material in the first discharge material portion deposited on the prescribed infrared radiation absorbing film formation region prior to the second discharging the second discharge material portion, and

second removing the second liquid carrier material in the second discharge material portion deposited on the prescribed infrared radiation absorbing film formation region.

24. The method of manufacturing as recited in claim 17, wherein

the mixing of the discharge material is performed by

mixing together a first infrared radiation absorbing substance and a first liquid carrier material having a first prescribed viscosity to form a first discharge material portion, and

mixing together a second infrared radiation absorbing substance having a smaller refractive index than the first infrared radiation absorbing substance and a second liquid carrier material having a second prescribed viscosity to form a second discharge material portion;

the filling of the pressure chamber with the discharge material is performed by

filling a first pressure chamber section having a first discharge opening with the first discharge material portion, and

a second pressure chamber section having a second discharge opening with the second discharge material portion;

the discharging of the discharge material is formed by

first discharging the first discharge material portion from the first discharge opening by adjusting the pressure inside the first pressure chamber to deposit on a first location of the prescribed infrared radiation absorbing film formation region, and

second discharging the second discharge material portion from the second discharge opening by adjusting the pressure inside the second pressure chamber to deposit on a second location of the prescribed infrared radiation absorbing film formation region that is different from the first location where the first discharge material first location was deposited; and

the removing of the liquid carrier material is performed by

removing at least one of the first and second liquid carrier material deposited on the prescribed infrared radiation absorbing film formation region.

25. The method of manufacturing as recited in claim 17, wherein

the mixing of the discharge material is performed by

mixing together a first infrared radiation absorbing substance and a first liquid carrier material having a first prescribed viscosity to form a first discharge material portion, and

mixing together a second infrared radiation absorbing substance and a second liquid carrier material having a second prescribed viscosity with a smaller viscosity than the first prescribed viscosity to form a second discharge material portion;

the filling of the pressure chamber with the discharge material is performed by

filling a first pressure chamber section having a first discharge opening with the first discharge material portion, and

a second pressure chamber section having a second discharge opening with the second discharge material portion;

the discharging of the discharge material is performed by

first discharging the first discharge material portion from the first discharge opening by adjusting the pressure inside the first pressure chamber to deposit on a first location of the prescribed infrared radiation absorbing film formation region, and

second discharging the second discharge material portion from the second discharge opening by adjusting the pressure inside the second pressure chamber to deposit on a second location of the prescribed infrared radiation absorbing film formation region that is different from the first location where the first discharge material first location was deposited; and

the removing of the liquid carrier material is performed by

removing at least one of the first and second liquid carrier material deposited on the prescribed infrared radiation absorbing film formation region.

26. A manufacturing apparatus for manufacturing infrared radiation detecting devices, comprising:

a plurality of pressure chambers having discharge openings to form an array sensor having a plurality of infrared radiation absorbing film regions with a predetermined pixel spacing; and

the discharge openings being arranged in a predetermined pattern with a predetermined spacing between adjacent ones of the discharge openings such that the predetermined spacing corresponds to an integer multiple of the predetermined pixel spacing including being equal to the predetermined pixel spacing.

27. A manufacturing apparatus for manufacturing infrared radiation detecting elements, comprising:

a pressure chamber having a discharge opening; and

a light emitting body;

a photosensor that detects the surface state of a measured body based on the change in reflectance of a surface with respect to light irradiated thereon from the light emitting body.

28. A manufacturing apparatus for manufacturing infrared radiation detecting element, comprising:

a pressure chamber having a discharge opening;

a heating device arranged in the vicinity of the discharge opening; and

a detector arranged to be coupled to an infrared radiation detecting element to detect an output signal value of a pixel of the infrared radiation detecting element.

29. A manufacturing apparatus for manufacturing infrared radiation detecting elements, comprising:

a pressure chamber having a discharge opening; and

an electrical capacitance detector arranged to be coupled to an infrared radiation detecting element to detect an electrical capacitance of the infrared radiation detecting element.