U.S. patent application number 17/240077 was filed with the patent office on 2022-06-23 for microelectromechanical infrared sensing device.
The applicant listed for this patent is Industrial Technology Research Institute. Invention is credited to MING-FA CHEN, BOR-SHIUN LEE.
Application Number | 20220196479 17/240077 |
Document ID | / |
Family ID | 1000006388529 |
Filed Date | 2022-06-23 |
United States Patent
Application |
20220196479 |
Kind Code |
A1 |
LEE; BOR-SHIUN ; et
al. |
June 23, 2022 |
MICROELECTROMECHANICAL INFRARED SENSING DEVICE
Abstract
A microelectromechanical infrared sensing device is provided,
which includes a substrate, a sensing plate, a reflecting plate, a
plurality of first supporting elements, a plurality of second
supporting elements and a plurality of stoppers. The second
supporting elements are connected to the sensing plate, such that
the sensing plate is suspended above the substrate. The reflecting
plate is disposed between the substrate and the sensing plate. The
first supporting elements are connected to the reflecting plate,
such that the reflecting plate is suspended between the substrate
and the reflecting plate. When the reflecting plate moves toward
the substrate and at least one of the stoppers contacts the
substrate or the reflecting plate, the distance between the
reflecting plate and the sensing plate increases.
Inventors: |
LEE; BOR-SHIUN; (New Taipei
City, TW) ; CHEN; MING-FA; (Taoyuan City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Industrial Technology Research Institute |
Hsinchu |
|
TW |
|
|
Family ID: |
1000006388529 |
Appl. No.: |
17/240077 |
Filed: |
April 26, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01J 5/20 20130101; G01J
5/0215 20130101; B81B 3/0029 20130101; B81B 2201/02 20130101 |
International
Class: |
G01J 5/02 20060101
G01J005/02; G01J 5/20 20060101 G01J005/20; B81B 3/00 20060101
B81B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2020 |
TW |
109145303 |
Claims
1. A microelectromechanical infrared sensing device, comprising: a
substrate; a sensing plate; a plurality of second supporting
elements, connected to the sensing plate, whereby the sensing plate
is suspended above the substrate; a reflecting plate, disposed
between the substrate and the sensing plate; a plurality of first
supporting elements, connected to the reflecting plate, whereby the
reflecting plate is suspended between the substrate and the sensing
plate; and a plurality of stoppers, disposed between the substrate
and the reflecting plate; wherein when the reflecting plate moves
toward the substrate and at least one of the stoppers contacts the
substrate or the reflecting plate, a distance between the
reflecting plate and the sensing plate increases.
2. The microelectromechanical infrared sensing device of claim 1,
further comprising an electrode layer disposed on the substrate and
a voltage source connected to the reflecting plate and the
electrode layer, wherein the voltage source generates a voltage
difference between the reflecting plate and the electrode layer so
as to control the reflecting plate to move.
3. The microelectromechanical infrared sensing device of claim 2,
further comprising an insulation layer covering the electrode
layer.
4. The microelectromechanical infrared sensing device of claim 1,
wherein the reflecting plate is able to move between a first
position relatively far from the substrate and a second position
relatively near the substrate, wherein: when the reflecting plate
is at the first position, the distance between the reflecting plate
and the sensing plate is a first distance; and when the reflecting
plate is at the second position, at least one of the stoppers is
sandwiched by the substrate and the reflecting plate and presses
against the substrate and the reflecting plate, and the distance
between the reflecting plate and the sensing plate is a second
distance; wherein the second distance is greater than the first
distance.
5. The microelectromechanical infrared sensing device of claim 4,
wherein when the reflecting plate is at the second position, the
distance between the substrate and the reflecting plate is
substantially equal to a height of at least one of the
stoppers.
6. The microelectromechanical infrared sensing device of claim 4,
wherein the stoppers comprises a plurality of first stoppers and a
plurality of second stoppers, and the reflecting plate is able to
move among the first position, the second position and a third
position, wherein: when the reflecting plate is at the second
position, the first stoppers are sandwiched between the substrate
and the reflecting plate and press against the substrate and the
reflecting plate; and when the reflecting plate is at the third
position, the second stoppers are sandwiched between the substrate
and the reflecting plate and press against the substrate and the
reflecting plate, and the distance between the reflecting plate and
the sensing plate is a third distance; wherein the third distance
is greater than the second distance.
7. The microelectromechanical infrared sensing device of claim 6,
wherein the first stoppers are connected to at least one of the
first supporting elements, and the second stoppers are connected to
the reflecting plate, wherein a height of at least one of the first
stoppers is greater than a height of at least one of the second
stoppers.
8. The microelectromechanical infrared sensing device of claim 6,
wherein a distance between the first stoppers and a center of the
reflecting plate is greater than a distance between the second
stoppers and the center of the reflecting plate.
9. The microelectromechanical infrared sensing device of claim 1,
wherein the stoppers are disposed on the reflecting plate, the
substrate or the first supporting elements.
10. The microelectromechanical infrared sensing device of claim 9,
wherein line segments connecting each of the two adjacent the
stoppers with each other form a polygon, and the polygon is
axial-symmetrical or central-symmetrical.
11. The microelectromechanical infrared sensing device of claim 1,
wherein the sensing plate comprises an upper infrared absorbing
layer and an infrared sensing layer, and the infrared sensing layer
comprises a lower surface facing the substrate and an upper surface
opposite to the lower surface, wherein the upper infrared absorbing
layer is disposed on the upper surface of the infrared sensing
layer.
12. The microelectromechanical infrared sensing device of claim 11,
wherein the sensing plate further comprises a lower infrared
absorbing layer disposed on the lower surface of the infrared
sensing layer.
13. The microelectromechanical infrared sensing device of claim 12,
wherein the upper infrared absorbing layer and the lower infrared
absorbing layer are made of a same material.
14. The microelectromechanical infrared sensing device of claim 12,
wherein a thickness of the upper infrared absorbing layer is
substantially equal to a thickness of the lower infrared absorbing
layer.
15. The microelectromechanical infrared sensing device of claim 1,
wherein the reflecting plate comprises an infrared reflecting layer
and a dielectric material layer, wherein the infrared reflecting
layer comprises a lower surface facing the substrate and the
dielectric material layer is disposed on the lower surface of the
infrared reflecting layer.
16. The microelectromechanical infrared sensing device of claim 1,
wherein each of the first supporting elements comprises an infrared
reflecting layer and a dielectric material layer, wherein the
infrared reflecting layer of each of the first supporting elements
comprises a lower surface adjacent to the substrate, and the
dielectric material layer of each of the first supporting elements
is disposed on the lower surface of the infrared reflecting layer
thereof.
17. The microelectromechanical infrared sensing device of claim 1,
wherein a stiffness of the first supporting elements in a direction
of a normal vector of the substrate is less than a stiffness of the
reflecting plate in the direction of the normal vector of the
substrate.
18. The microelectromechanical infrared sensing device of claim 1,
wherein each of the second supporting elements further comprises a
lower infrared absorbing layer adjacent to the substrate, an
infrared sensing layer and an upper infrared absorbing layer,
wherein the infrared sensing layer of each of the second supporting
elements is disposed between the upper infrared absorbing layer and
the lower infrared absorbing layer thereof.
19. The microelectromechanical infrared sensing device of claim 1,
further comprises a fixation base, wherein: one end of each of the
first supporting elements is provided with a first anchor fixed on
the substrate, and the fixation base is fixed on the first anchor
of the first supporting element; and one end of each of the second
supporting element is provided with a second anchor, and the second
anchor is fixed on the fixation base.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] All related applications are incorporated by reference. The
present application is based on, and claims priority from, Taiwan
Application Serial Number 109145303, filed on Dec. 21, 2020, the
disclosure of which is hereby incorporated by reference herein in
its entirety.
TECHNICAL FIELD
[0002] The technical field relates to microelectromechanical
infrared sensing device with absorption rate active adjustment
function.
BACKGROUND
[0003] Currently, the microelectromechanical infrared sensing
devices have been successfully applied to various fields. So as to
meet different requirements of various environments, the
microelectromechanical infrared sensing devices need to support
wider temperature range. Thus, the microelectromechanical infrared
sensing devices must be able to automatically adjust the absorbing
rates therefore according to different environmental
temperatures.
[0004] However, a thermal insulation structure of a currently
available microelectromechanical infrared sensing devices cannot
effectively reduce the heat loss, so the performance of the
microelectromechanical infrared sensing devices require further
improvement.
[0005] Besides, since the distance between the infrared absorbing
layer and the infrared reflecting layer of the currently available
microelectromechanical infrared sensing device is fixed, a
high-resolution readout circuit would go into saturation easily
while being applied to read signals from the microelectromechanical
infrared sensing device. Therefore, a limitation upon the sensing
range of the microelectromechanical infrared sensing devices is
thus inevitable.
[0006] Moreover, since the infrared absorbing layer of the
currently available microelectromechanical infrared sensing device
is sensitive to surrounding temperature, from which non-uniform
thermal stress and corresponding thermal strain (mainly in bending)
would occur to the microelectromechanical infrared sensing device.
As a result, the distance between the infrared absorbing layer and
the infrared reflecting layer may not be consistent, which
significantly decreases the sensing accuracy of the
microelectromechanical infrared sensing apparatus.
SUMMARY
[0007] An embodiment of the disclosure relates to a
microelectromechanical infrared sensing device, comprising a
substrate, a sensing plate, a reflecting plate and a plurality of
first supporting elements, a plurality of second supporting
elements and a plurality of stoppers. The second supporting
elements are connected to the sensing plate, such that the sensing
plate is suspended above the substrate. The reflecting plate is
disposed between the substrate and the sensing plate. The first
supporting elements are connected to the reflecting plate, such
that the reflecting plate is suspended between the substrate and
the reflecting plate. When the reflecting plate moves toward the
substrate and at least one of the stoppers contacts the substrate
or the reflecting plate, the distance between the reflecting plate
and the sensing plate increases.
[0008] Further scope of applicability of the present application
will become more apparent from the detailed description given
hereinafter. However, it should be understood that the detailed
description and specific examples, while indicating exemplary
embodiments of the disclosure, are given by way of illustration
only, since various changes and modifications within the spirit and
scope of the disclosure will become apparent to those skilled in
the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1A.about.FIG. 1B are perspective views of a
microelectromechanical infrared sensing device in accordance with
one embodiment of the disclosure.
[0010] FIG. 2 is a cross-sectional view of the
microelectromechanical infrared sensing device in accordance with
one embodiment of the disclosure; FIG. 2 shows that the reflecting
plate of the microelectromechanical infrared sensing device is at a
first position.
[0011] FIG. 3 is another cross-sectional view of the
microelectromechanical infrared sensing device in accordance with
one embodiment of the disclosure; FIG. 3 shows that the reflecting
plate of the microelectromechanical infrared sensing device is at a
second position.
[0012] FIG. 4A.about.FIG. 4B are cross-sectional views of the
microelectromechanical infrared sensing device in accordance with
one embodiment of the disclosure.
[0013] FIG. 5 is a perspective view of a microelectromechanical
infrared sensing device in accordance with one embodiment of the
disclosure.
[0014] FIG. 6 is a perspective view of a microelectromechanical
infrared sensing device in accordance with one embodiment of the
disclosure.
[0015] FIG. 7 is a perspective view of a microelectromechanical
infrared sensing device in accordance with one embodiment of the
disclosure.
[0016] FIG. 8 is a perspective view of a microelectromechanical
infrared sensing device in accordance with one embodiment of the
disclosure.
[0017] FIG. 9 is a perspective view of a microelectromechanical
infrared sensing device in accordance with one embodiment of the
disclosure.
[0018] FIG. 10 is a perspective view of a microelectromechanical
infrared sensing device in accordance with one embodiment of the
disclosure.
[0019] FIG. 11 is a perspective view of a microelectromechanical
infrared sensing device in accordance with one embodiment of the
disclosure.
[0020] FIG. 12 is a perspective view of a microelectromechanical
infrared sensing device in accordance with one embodiment of the
disclosure.
[0021] FIG. 13A.about.FIG. 13B are perspective views of a
microelectromechanical infrared sensing device in accordance with
one embodiment of the disclosure.
[0022] FIG. 14.about.FIG. 16 are cross-sectional views of the
microelectromechanical infrared sensing device in accordance with
one embodiment of the disclosure.
[0023] FIG. 17A.about.FIG. 17B are perspective views of a
microelectromechanical infrared sensing device in accordance with
one embodiment of the disclosure.
[0024] FIG. 18.about.FIG. 19 are cross-sectional views of the
microelectromechanical infrared sensing device in accordance with
one embodiment of the disclosure.
DETAILED DESCRIPTION
[0025] In the following detailed description, for purposes of
explanation, numerous specific details are set forth in order to
provide a thorough understanding of the disclosed embodiments. It
will be apparent, however, that one or more embodiments may be
practiced without these specific details. In other instances,
well-known structures and devices are schematically shown in order
to simplify the drawing.
[0026] Please refer to FIG. 1A, FIG. 1B, FIG. 2 and FIG. 3, which
are perspective views and cross-sectional views of a
microelectromechanical infrared sensing device 1 in accordance with
one embodiment of the disclosure respectively. As shown in FIG. 1A
and FIG. 1B, the microelectromechanical infrared sensing device 1
includes a substrate 10, a reflecting plate 11, a sensing plate 12,
a plurality of first supporting elements 13A, a plurality of second
supporting elements 13B, a plurality of fixation bases 14, a
plurality of stoppers 15, a voltage source 16, a controller 17 and
an electrode layer 18.
[0027] The electrode layer 18 is disposed on the substrate 10. In
one embodiment, the substrate 10 may be a silicon substrate or
other similar components.
[0028] Each of the first supporting elements 13A includes a first
connecting portion A1, a first bending portion A2, a first
supporting portion A3 and a first anchor A4.
[0029] The first connecting portion A1 is connected to the
reflecting plate 11 and the first bending portion A2. The first
supporting portion A3 is connected to the first bending portion A2
and the first anchor A4. One end of each of the fist supporting
elements 13A is fixed on the substrate 10 via the first anchor A4
and the other end thereof is connected to the reflecting plate 11
via the first connecting portion A1. Therefore, the reflecting
plate 11 can be suspended above the substrate 10 via the first
supporting elements 13A, such that a first thermal insulation
chamber H1 is formed between the reflecting plate 11 and the
substrate 10.
[0030] The fixation bases 14 are fixed on the first anchors A4 of
the first supporting elements 13A respectively. Similarly, each of
the second supporting elements 13B includes a second connecting
portion B1, a second bending portion B2, a second supporting
portion B3 and a second anchor B4. The second connecting portion B1
is connected to the sensing plate 12 and the second bending portion
B2, and the second supporting portion B3 is connected to the second
bending portion B2 and the second anchor B4. One end of each of the
second supporting elements 13B is fixed on the corresponding
fixation base 14 via the second anchor B4, and the other end
thereof is connected to the sensing plate 12 via the second
connecting portion Bl. Accordingly, the sensing plate 12 can be
suspended above the reflecting plate 11 via the second supporting
elements 13B, such that a second thermal insulation chamber H2 is
formed between the sensing plate 12 and the reflecting plate 11.
The sensing plate 12 is fixed on the fixation bases 14 via the
second supporting elements 13B; thus, although the distance between
the reflecting plate 11 and the substrate 10 and the distance
between the reflecting plate 11 and the sensing plate 12 may be
changed, the sum of the two distances remains constant.
[0031] As described above, the microelectromechanical infrared
sensing device 1 of the disclosure has a dual-layer structure.
Namely, the reflecting plate 11 is suspended above the substrate 10
and the sensing plate 12. Accordingly, the space between the
sensing plate 12 and the substrate 10 can be divided into two
thermal insulation chambers (i.e. the fist thermal insulation
chamber H1 and the second thermal insulation chamber H2).
[0032] In the embodiment, the stoppers 15 are disposed on the lower
surface of the reflecting plate 11, and between the substrate 10
and the reflecting plate 11. The stoppers 15 may be arranged on a
basis of a central-symmetrical polygon. In other words, the line
segments L1 connecting each of the two adjacent the stoppers 15
with each other form a central-symmetrical polygon. In the
embodiment, the stoppers 15 are arranged on a basis of a rectangle;
namely, the line segments L1 form, but not limited to, a rectangle.
In another embodiment, the line segments L1 connecting each of the
two adjacent the stoppers 15 can form a rhombus, a circle or other
central-symmetrical polygons. In still another embodiment, the line
segments L1 connecting each of the two adjacent the stoppers 15 can
form a triangle, a pentagon, a hexagon, other axial symmetrical
polygons or irregular shapes. In the embodiment, the stoppers 15
have the same height.
[0033] The voltage source 16 is electrically connected to the
electrode layer 18 on the substrate 10 and the reflecting plate 11.
The controller 17 is electrically connected to the voltage source
16 and controls the voltage source 16 to output a voltage so as to
form a voltage difference between the electrode layer 18 and the
reflecting plate 11 and then control the reflecting plate 11 to
move via the voltage difference. In one embodiment, the controller
17 may be a microcontroller unit (MCU), a central processing unit
(CPU), an application-specific integrated circuit (ASIC) or other
similar components.
[0034] FIG. 2 is the cross-sectional view of the
microelectromechanical infrared sensing device 1 along the section
line I-I in FIG. 1A. As shown in FIG. 2, the reflecting plate 11
includes an infrared reflecting layer 111 and a dielectric material
layer 112. The infrared reflecting layer 111 of the reflecting
plate 11 includes a lower surface S1 facing the substrate 10 and an
upper surface S2 opposite to the lower surface S1. The dielectric
material layer 112 of the reflecting plate 11 is disposed on the
lower surface S1 of the infrared reflecting layer 111. Besides, the
voltage source 16 is electrically connected to the electrode layer
18 of the substrate 10 and the infrared reflecting layer 111 of the
reflecting plate 11. In one embodiment, the infrared reflecting
layer 111 of the reflecting plate 11 may be a metal layer having
high reflecting rate, such as Al, Au, Ag, W, Cu, Ti, Ta, or Mo,
etc., such that the infrared reflecting layer 111 may serve as
another electrode layer corresponding to the electrode layer 18. In
one embodiment, the dielectric material layer 112 of the reflecting
plate 11 may be made of a dielectric material, such as SiN.sub.x,
SiO.sub.x, or SiO.sub.xN.sub.y, etc., so as to provide the
insulation effect. The stoppers 15 and the dielectric material
layer 112 of the reflecting plate 11 may be made of the same
material.
[0035] Similarly, each of the first supporting elements 13A also
includes an infrared reflecting layer 131A and a dielectric
material layer 132A. The infrared reflecting layer 131A of each of
the first supporting elements 13A includes a lower surface S1'
adjacent to the substrate 10 and an upper surface S2' opposite to
the lower surface S1'. Besides, the dielectric material layer 132A
of each of the first support elements 13A is disposed on the lower
surface S1' of the infrared reflecting layer 131A thereof.
[0036] The sensing plate 12 includes an upper infrared absorbing
layer 121, an infrared sensing layer 123 and a lower infrared
absorbing layer 122. The infrared sensing layer 123 comprises a
lower surface U1 facing the substrate 10 and an upper surface U2
opposite to the lower surface U1. The upper infrared absorbing
layer 121 of the sensing plate 12 is disposed on the upper surface
U2 of the infrared sensing layer 123 and the lower infrared
absorbing layer 122 of the sensing plate 12 is disposed on the
lower surface U1 of the infrared sensing layer 123, such that the
infrared sensing layer 123 of the sensing plate 12 is between the
upper infrared absorbing layer 121 and the lower infrared absorbing
layer 122. In the embodiment, the sensing plate 12 is a symmetrical
structure. Namely, the upper infrared absorbing layer 121 and the
lower infrared absorbing layer 122 of the sensing plate 12 may be
made of the same material. In addition, the thickness of the upper
infrared absorbing layer 121 may be substantially equal to the
thickness of the lower infrared absorbing layer 122. In one
embodiment, the upper infrared absorbing layer 121 and the lower
infrared absorbing layer 122 of the sensing plate 12 may be made of
a dielectric material, such as SiN.sub.x, SiO.sub.x, or
SiO.sub.xN.sub.y, etc. In one embodiment, the infrared sensing
layer 123 of the sensing plate 12 may be an alloy layer, a metal
compound layer, a metal oxide layer, a silicon compound layer, or a
silicon layer, etc., such as SiGe, VO.sub.x, p-Si, a-Si, or
Ti-silicide, etc. Since the upper infrared absorbing layer 121 and
the lower infrared absorbing layer 122 of the sensing plate 12 may
be made of the same material, and the thickness of the upper
infrared absorbing layer 121 may be substantially equal to the
thickness of the lower infrared absorbing layer 122, these layers
have the same material properties, structure and size. The
aforementioned material properties may be coefficient of thermal
expansion, Young's Modulus, etc. Accordingly, the symmetric
structure of the sensing plate 12 can achieve stress balance, which
can prevent from warpage and deformation during the manufacturing
process of the sensing plate 12. For the same reason, when the
thickness and material of the upper infrared absorbing layer 121
are the same with those of the lower infrared absorbing layer 122,
the complexity and cost of the manufacturing process of the sensing
plate 12 can be obviously decreased. In another embodiment, the
sensing plate may have an unsymmetrical structure and not be
limited to symmetrical structure.
[0037] Similarly, each of the second supporting elements 13B
includes a lower infrared absorbing layer 132B adjacent to the
substrate 10, an infrared sensing layer 133B and an upper infrared
absorbing layer 131B. The infrared sensing layer 133B of the second
supporting element 13B includes a lower surface U1' adjacent to the
substrate 10 and an upper surface U2' opposite to the lower surface
U1'. The upper infrared absorbing layer 131B of the second
supporting element 13B is disposed on the upper surface U2' of the
infrared sensing layer 133B and the lower infrared absorbing layer
132B of the infrared sensing layer 133B is disposed on the lower
surface U1' of the infrared sensing layer 133B, such that the
infrared sensing layer 133B of the second supporting element 13B is
between the upper infrared absorbing layer 131B and the lower
infrared absorbing layer 132B. Each of the second supporting
elements 13B may also have a symmetrical structure. That is to say,
the upper infrared absorbing layer 131B and the lower infrared
absorbing layer 132B of the second supporting element 13B may be
made of the same material. In addition, the thickness of the upper
infrared absorbing layer 131B may be substantially equal to the
thickness of the lower infrared absorbing layer 132B. Since the
upper infrared absorbing layer 131B and the lower infrared
absorbing layer 132B of the second supporting element 13B may be
made of the same material, and the thickness of the upper infrared
absorbing layer 131B may be substantially equal to the thickness of
the lower infrared absorbing layer 132B, these layers have the same
material properties, structure and size. Accordingly, the second
supporting elements 13B can have low thermal stress and low warpage
during the manufacturing process. When the upper infrared absorbing
layer 131B and the lower infrared absorbing layer 132B of the
second supporting element 13B are made of the same material and
have the same thickness, the second supporting elements 13B and the
sensing plate 12 can be manufactured by the same manufacturing
process. Therefore, the complexity and cost of the manufacturing
process of the microelectromechanical infrared sensing device 1 can
be greatly decreased.
[0038] The sensing plate 12 can change the resistance thereof after
absorbing the radiant energy of the incoming infrared light and the
reflecting plate 11 can reflect the infrared light not absorbed by
the sensing plate 12 to the sensing plate 12, such that the sensing
plate 12 can absorb the radiant energy of the reflected infrared
light again. When the controller 17 controls the voltage source 16
to generate a voltage difference between the electrode layer 18 of
the substrate 10 and the infrared reflecting layer 111 of the
reflecting plate 11, the voltage difference can change the
electrostatic force between the electrode layer 18 and the
reflecting plate 11, thus the reflecting plate 11 can move toward
the substrate 10. Accordingly, the distance between the reflecting
plate 11 and the sensing plate 12 is changed. Such a mechanism can
vary the absorbing rate of the sensing plate 12 so as to avoid
possible saturation in the readout circuit. Thereupon, the sensing
range of the microelectromechanical infrared sensing device 1 can
be effectively expanded.
[0039] As shown in FIG. 2, when the controller 17 does not turn on
the voltage source 16, the reflecting plate 11 is at the position
closest to the sensing plate 12; in other words, the reflecting
plate 12 is at the first position, as shown in FIG. 2. When the
reflecting plate 11 is at the first position, the distance between
the reflecting plate 11 and the sensing plate 12 is first distance
D1, and the microelectromechanical infrared sensing device 1
operates in a first absorbing rate mode.
[0040] As shown in FIG. 3, when the temperature (hereinafter
"target temperature") of the sensing target of the
microelectromechanical infrared sensing device 1 changes to be T1,
the controller 17 turns on the voltage source 16 to generate a
first control voltage V1 so as to control the reflecting plate 11
to move, from the first position (as shown in FIG. 2) away from the
substrate 10, toward the substrate 10. When the stoppers 15 contact
the substrate 10, the reflecting plate 11 stops moving and stays at
the second position, as shown in FIG. 3. When the reflecting plate
11 is at the second position, the distance between the reflecting
plate 11 and the sensing plate 12 is second distance D2. Meanwhile,
when the stoppers 15 are sandwiched between the substrate 10 and
the reflecting plate 11, and press against the substrate 10 and the
reflecting plate 11. The second distance D2 of the second position
is greater than the first distance D1 of the first position. When
the reflecting plate 11 is at the second position, the distance
between the reflecting plate 11 and the substrate 10 is
substantially equal to the height of the stoppers 15. Thus, the
reflecting plate 11 would not contact the electrode layer 18, and
the distance between the sensing plate and the reflecting plate 11
is maximized At this moment, the microelectromechanical infrared
sensing device 1 operates in a second absorbing rate mode.
[0041] When the target temperature of the microelectromechanical
infrared sensing device 1 changes to be T2 (T2>T1), the
controller 17 turns off the voltage source 16 (i.e. the voltage
source 16 is in off state) so as to control the reflecting plate 11
to move in the direction away from the substrate 10 and then stop
after the reflecting plate 11 returns back at the first position;
that is to say, the microelectromechanical infrared sensing device
1 returns back to the state that the distance between the
reflecting plate 11 and the sensing plate 12 is first distance D1.
At this moment, the reflecting plate 11 is at the first position,
as shown in FIG. 2, and the microelectromechanical infrared sensing
device 1 operates in the first absorbing rate mode so as to prevent
the readout circuit from saturation. In this way, the
microelectromechanical infrared sensing device 1 can obtain
accurate sensing results.
[0042] As described above, the absorbing rate of the
microelectromechanical infrared sensing device 1 can be adjusted by
changing the position of the reflecting plate 11 in order to
increase the sensing range thereof.
[0043] This embodiment is just for illustration; the relation
between the height of the reflecting plate 11 and the absorbing
rate can be changed by modifying the structural design of the
microelectromechanical infrared sensing device 1. In other words,
the height of the reflecting plate 11 may be proportional to or
inversely proportional to the absorbing rate. More specifically,
when the reflecting plate 11 descends from the highest positon to
the lowest position, the microelectromechanical infrared sensing
device 1 changes from the low absorbing rate mode to the high
absorbing rate mode.
[0044] In another embodiment, when the reflecting plate 11 descends
from the highest positon to the lowest position, the
microelectromechanical infrared sensing device 1 changes from the
high absorbing rate mode to the low absorbing rate mode.
[0045] As set forth above, when the target temperature of the
microelectromechanical infrared sensing device 1 is high, the
microelectromechanical infrared sensing device 1 can be switched to
the first absorbing rate mode by adjusting the voltage outputted by
the voltage source 16. On the contrary, when the target temperature
of the microelectromechanical infrared sensing device 1 is low, the
microelectromechanical infrared sensing device 1 can be also
switched to the second absorbing rate mode by adjusting the voltage
outputted by the voltage source 16. In this way, the
microelectromechanical infrared sensing device 1 can have multiple
operating points P1 and P2, such that the total thermal power
absorbed by the microelectromechanical infrared sensing device 1
can be always lower than a designated value in order to prevent
from the saturation of the high-resolution readout circuit.
[0046] Moreover, the first thermal insulation chamber H1(between
the reflecting plate 11 and the substrate 10) and the second
thermal insulation chamber H2 (between the sensing plate 12 and the
reflecting plate 11) can effectively enhance the thermal insulation
effect and reduce heat loss no matter what the operating mode of
the microelectromechanical infrared sensing device 1 is. Therefore,
the above dual-layer structure can effectively improve the
performance of the microelectromechanical infrared sensing device
1.
[0047] Please refer to FIG. 4A, which is a cross-sectional view of
the microelectromechanical infrared sensing device 1 in accordance
with one embodiment of the disclosure. The difference between this
embodiment and the embodiment of FIG. 2 and FIG. 3 is that the
reflecting plate 11 of this embodiment as FIG. 4A has only the
infrared reflecting layer 111 and the stoppers 15 are disposed on
the lower surface Si of the infrared reflecting layer 111. The
infrared reflecting layer 111 of the reflecting plate 11 and the
stoppers 15 may be made of the metals with high reflecting rate,
such as Al, Au, Ag, W, Gu, Ti, Ta, or Mo, etc. As the reflecting
plate 11 has only the infrared reflecting layer 111, the electrode
layer 18 disposed on the substrate 10 needs to be provided with an
insulation layer 181.
[0048] Please refer to FIG. 4B, which is a cross-sectional view of
the microelectromechanical infrared sensing device 1 in accordance
with one embodiment of the disclosure. The difference between this
embodiment and the embodiment of FIG. 2 and FIG. 3 is that the
sensing plate 12 of this embodiment has only the upper infrared
absorbing layer 121 and the infrared sensing layer 123. Therefore,
the sensing plate 12 of this embodiment is a plate having a
dual-layer structure consisting of the upper infrared absorbing
layer 121 and the infrared sensing layer 123. Compared with the
sensing plate of the triple-layer structure, the absorbing rate of
the sensing plate 12 of this embodiment may be lower, but the
sensing plate 12 of this embodiment can still have the function of
absorbing and sensing infrared light.
[0049] Please refer to FIG. 5, which is a perspective view of a
microelectromechanical infrared sensing device 1 in accordance with
one embodiment of the disclosure. As shown in FIG. 5, the stoppers
15 of the embodiment are disposed on the lower surface of the
reflecting plate 11 and the line segments L2 connecting each of the
two adjacent the stoppers 15 can form a triangle.
[0050] Please refer to FIG. 6, which is a perspective view of a
microelectromechanical infrared sensing device 1 in accordance with
one embodiment of the disclosure. As shown in FIG. 6, the stoppers
15 of the embodiment are disposed on the lower surface of the
reflecting plate 11 and the line segments L3 connecting each of the
two adjacent the stoppers 15 can form a pentagon.
[0051] Please refer to FIG. 7, which is a perspective view of a
microelectromechanical infrared sensing device 1 in accordance with
one embodiment of the disclosure. As shown in FIG. 7, the stoppers
15 of the embodiment are disposed on the lower surface of the
reflecting plate 11 and the line segments L4 connecting each of the
two adjacent the stoppers 15 can form a hexagon.
[0052] Please refer to FIG. 8, which is a perspective view of a
microelectromechanical infrared sensing device 1 in accordance with
one embodiment of the disclosure. As shown in FIG. 8, the
microelectromechanical infrared sensing device 1 of this embodiment
has only one stopper 15 disposed on the lower surface of the
reflecting plate 11; the stopper 15 may be, but not limited to, a
circular ring. In another embodiment, the stopper 15 may be a
rectangular ring or a ring in a different shape.
[0053] Please refer to FIG. 9, which is a perspective view of a
microelectromechanical infrared sensing device 1 in accordance with
one embodiment of the disclosure. As shown in FIG. 9, each of the
stoppers 15 of this embodiment is disposed on one end of the first
connecting portion A1 of the corresponding first supporting element
13A. When the controller 17 does not turn on the voltage source 16,
the reflecting plate 11 is at the first position; in this case, the
distance between the reflecting plate 11 and the sensing plate 12
is first distance D1. At this moment, the microelectromechanical
infrared sensing device 1 operates in the first absorbing rate mode
when the reflecting plate 11 is at the first position. Then, when
the controller 17 of this embodiment turns on the voltage source 16
to output the first control voltage V1 so as to control the
reflecting plate 11 to move from the first position away from the
substrate 10 toward the substrate 10, and after the stoppers 15
disposed on the first connecting portions A1 of the first
supporting elements 13A contact the substrate 10, the reflecting
plate 11 stops moving and arrives the second position. When the
reflecting plate 11 is at the second position, the distance between
the reflecting plate 11 and the sensing plate 12 is second distance
D2. Meanwhile, the microelectromechanical infrared sensing device 1
operates in the second absorbing rate mode.
[0054] Please refer to FIG. 10, which is a perspective view of a
microelectromechanical infrared sensing device 1 in accordance with
one embodiment of the disclosure. As shown in FIG. 10, each of the
stoppers 15 of this embodiment is disposed on the center of the
first connecting portion A1 of the corresponding first supporting
element 13A. When the controller 17 does not turn on the voltage
source 16, the reflecting plate 11 is at the first position; in
this case, the distance between the reflecting plate 11 and the
sensing plate 12 is first distance D1. At this moment, the
microelectromechanical infrared sensing device 1 operates in the
first absorbing rate mode when the reflecting plate 11 is at the
first position. When the controller 17 of this embodiment turns on
the voltage source 16 to output the first control voltage V1 so as
to control the reflecting plate 11 to move, from the first position
away from the substrate 10 toward the substrate 10, and after the
stoppers 15 disposed on the first connecting portions A1 of the
first supporting elements 13A contact the substrate 10, the
reflecting plate 11 stops moving and arrives the second position.
When the reflecting plate 11 is at the second position, the
distance between the reflecting plate 11 and the sensing plate 12
is second distance D2. Meanwhile, the microelectromechanical
infrared sensing device 1 operates in the second absorbing rate
mode.
[0055] Please refer to FIG. 11, which is a perspective view of a
microelectromechanical infrared sensing device 1 in accordance with
one embodiment of the disclosure. As shown in FIG. 11, each of the
stoppers 15 of this embodiment is disposed on the first bending
portion A2 of the corresponding first supporting element 13A. When
the controller 17 does not turn on the voltage source 16, the
reflecting plate 11 is at the first position; in this case, the
distance between the reflecting plate 11 and the sensing plate 12
is first distance D1. At this moment, the microelectromechanical
infrared sensing device 1 operates in the first absorbing rate mode
when the reflecting plate 11 is at the first position. When the
controller 17 of this embodiment turns on the voltage source 16 to
output the first control voltage V1 so as to control the reflecting
plate 11 to move, from the first position away from the substrate
10 toward the substrate 10, and after the stoppers 15 disposed on
the first bending portions A2 of the first supporting elements 13A
contact the substrate 10, the reflecting plate 11 stops moving and
arrives the second position. When the reflecting plate 11 is at the
second position, the distance between the reflecting plate 11 and
the sensing plate 12 is second distance D2. Meanwhile, the
microelectromechanical infrared sensing device 1 operates in the
second absorbing rate mode.
[0056] Please refer to FIG. 12, which is a perspective view of a
microelectromechanical infrared sensing device 1 in accordance with
one embodiment of the disclosure. As shown in FIG. 12, each of the
stoppers 15 of this embodiment is disposed on the center of the
first supporting portion A3 of the corresponding first supporting
element 13A. When the controller 17 does not turn on the voltage
source 16, the reflecting plate 11 is at the first position; in
this case, the distance between the reflecting plate 11 and the
sensing plate 12 is first distance D1. At this moment, the
microelectromechanical infrared sensing device 1 operates in the
first absorbing rate mode when the reflecting plate 11 is at the
first position. When the controller 17 of this embodiment turns on
the voltage source 16 to output the first control voltage V1 so as
to control the reflecting plate 11 to move, from the first position
away from the substrate 10 toward the substrate 10, and after the
stoppers 15 disposed on the first supporting portions A3 of the
first supporting elements 13A contact the substrate 10, the
reflecting plate 11 stops moving and arrives the second position.
When the reflecting plate 11 is at the second position, the
distance between the reflecting plate 11 and the sensing plate 12
is second distance D2. Meanwhile, the microelectromechanical
infrared sensing device 1 operates in the second absorbing rate
mode.
[0057] The embodiment just exemplifies the disclosure and is not
intended to limit the scope of the disclosure. Any equivalent
modification and variation according to the spirit of the
disclosure is to be also included within the scope of the following
claims and their equivalents.
[0058] It is worthy to point out that the currently available
microelectromechanical infrared sensing devices have no effective
thermal insulation structure, so these devices cannot effectively
reduce the heat loss thereof. Thus, the performance and the sensing
accuracy of these microelectromechanical infrared sensing devices
cannot be effectively increased. In contrast, according to one
embodiment of the disclosure, the reflecting plate 11 of the
microelectromechanical infrared sensing device 1 is suspended above
the substrate 10 and the sensing plate 12 is suspended above the
reflecting plate 11, so two thermal insulation chambers (i.e. the
first thermal insulation chamber H1 and the second thermal
insulation chamber H2) are formed. The structure can significantly
enhance the thermal insulation effect of the microelectromechanical
infrared sensing device 1 and reduce the heat loss thereof. Thus,
the performance and the sensing accuracy of the
microelectromechanical infrared sensing device 1 can be effectively
enhanced.
[0059] Also, if the temperature of the sensing target is high
(i.e., the energy of the infrared light radiated by the sensing
target is high), the high-resolution readout circuit would tend to
be saturated when the sensing signals of the currently available
conventional microelectromechanical infrared sensing device are
read out. The above situation causes the microelectromechanical
infrared sensing device unable to sense the sensing target of high
temperature anymore, so the sensing range of the currently
available microelectromechanical infrared sensing device is
limited. In contrast, according to the embodiments of the
disclosure, the distance between the reflecting plate 11 and the
substrate 10 of the microelectromechanical infrared sensing device
1 can be adjusted via the voltage source 16, and simultaneously
change the distance between the sensing plate 12 and the reflecting
plate 11 in order to adjust the absorbing rate of the
microelectromechanical infrared sensing device 1. Accordingly, the
microelectromechanical infrared sensing device 1 can be operated in
different absorbing rate modes, so can be applied to the
environments with different temperatures and prevent from the
saturation of the readout circuit. Thus, the sensing range of the
microelectromechanical infrared sensing device 1 can be greatly
increased.
[0060] Moreover, according to the embodiments of the disclosure,
the sensing plate 12 of the microelectromechanical infrared sensing
device 1 is a symmetrical structure. Namely, the upper infrared
absorbing layer 121 and the lower infrared absorbing layer 122 of
the sensing plate 12 are made of the same material, have the same
thickness and symmetrically disposed on the two sides of the
infrared sensing layer 123 of the sensing plate 12. This
symmetrical structure can balance the stress of the sensing plate
12 when the temperature is changed so as to prevent from warpage
and deformation, which can further enhance the sensing accuracy of
the microelectromechanical infrared sensing device 1 and simplify
the manufacturing process thereof.
[0061] Please refer to FIG. 13A, FIG. 13B, FIG. 14, FIG. 15 and
FIG. 16, which are perspective views and cross-sectional views of a
microelectromechanical infrared sensing device 2 in accordance with
one embodiment of the disclosure respectively. FIG. 14 is the
cross-sectional view of the microelectromechanical infrared sensing
device 2 along line II-II in FIG. 13A. As shown in FIG. 13A, FIG.
13B and FIG. 14, the microelectromechanical infrared sensing device
2 includes a substrate 20, a reflecting plate 21, a sensing plate
22, a plurality of first supporting elements 23A, a plurality of
second supporting elements 23B, a plurality of fixation bases 24, a
plurality of stoppers 25a & 25b, a voltage source 26, a
controller 27 and an electrode layer 28. The reflecting plate 21
includes an infrared reflecting layer 211 and a dielectric material
layer 212. Each of the first supporting elements 23A includes a
first connecting portion A1, a first bending portion A2, a first
supporting portion A3 and a first anchor A4, and also has the
layered structure including an infrared reflecting layer 231A and a
dielectric material layer 232A. The sensing plate 22 includes an
upper infrared absorbing layer 221, an infrared sensing layer 223
and a lower infrared absorbing layer 222. Each of the second
supporting elements 23B includes a second connecting portion B1, a
second bending portion B2, a second supporting portion B3 and a
second anchor B4, and also has the layered structure including an
upper infrared absorbing layer 231B, an infrared sensing layer 233B
and a lower infrared absorbing layer 232B. The stoppers 25a &
25b are disposed on the lower surface of the reflecting plate 21.
Similarly, the reflecting plate 21 of the microelectromechanical
infrared sensing device 2 is suspended above the substrate 20 and
the sensing plate 22 is suspended above the reflecting plate 21.
Accordingly, two thermal insulation chambers (i.e. the first
thermal insulation chamber H1 and the second thermal insulation
chamber H2) can be formed between the reflecting plate 21 and the
substrate 20 and between the reflecting plate 21 and the sensing
plate 22 respectively, which can significantly enhance the thermal
insulation effect of the microelectromechanical infrared sensing
device 2 and reduce the heat loss thereof.
[0062] The above elements are similar to the embodiments of FIG.
1.about.FIG. 12, so will not be described therein again. The
difference between this embodiment and the embodiments of FIG.
1.about.FIG. 12 is that the stoppers include a plurality of first
stoppers 25a and a plurality of second stoppers 25b. The first
stoppers 25a have the same height and the second stoppers 25b have
the same height. In this embodiment, the height of the first
stoppers 25a is greater than the height of the second stoppers 25b.
The distance between each of the first stoppers 25a and the center
of the reflecting plate 21 is greater than the distance between
each of the second stoppers 25b and the center of the reflecting
plate 21. That is to say, the first stoppers 25a are closer to the
edge of the reflecting plate 21. In another embodiment, the first
stoppers 25a may also have different heights. Similarly, the second
stoppers 25b may also have different heights.
[0063] The above structure enables the microelectromechanical
infrared sensing device 2 to have more operating points. As shown
in FIG. 14, when the controller 27 has not yet turned on the
voltage source 26, the reflecting plate 21 is at the position
closest to the sensing plate 22; namely, the reflecting plate 21 is
at the first position shown in FIG. 14. At the moment, the distance
between the reflecting plate 21 and the sensing plate 22 is first
distance D1, and the microelectromechanical infrared sensing device
2 operates in a first absorbing rate mode.
[0064] As shown in FIG. 15, when the target temperature of the
microelectromechanical infrared sensing device 2 changes to be T2,
the controller 27 turns on the voltage source 26 to output the
first control voltage V1 so as to control the reflecting plate 21
to move, from the first position away from the substrate 20, toward
the substrate 20. Then, the reflecting plate 21 stops moving and
stays at the second position when the first stoppers 25a contact
the substrate 20. At the moment, the distance between the
reflecting plate 21 and the sensing plate 22 is second distance D2;
in this case, the microelectromechanical infrared sensing device 2
operates in a second absorbing rate mode. When the reflecting plate
21 is at the second position, the first stoppers 25a are sandwiched
between the substrate 20 and the reflecting plate 21, and press
against the substrate 20 and the reflecting plate 21. At the
moment, the distance D2' between the reflecting plate 21 and the
substrate 20 is substantially equal to the height of the first
stoppers 25a, such that the reflecting plate 21 can be separated
from the electrode layer 28 and does not contact the electrode
layer 28.
[0065] As shown in FIG. 16, when the target temperature of the
microelectromechanical infrared sensing device 2 further changes to
be T1, the controller 27 drives the voltage source 26 to output the
second control voltage V2 (V2>V1) to control the reflecting
plate 21 to further move toward the substrate 20. Then, when the
second stoppers 25b contact the substrate 20, the reflecting plate
21 stops moving and stays at the third position. At the moment, the
distance between the reflecting plate 21 and the sensing plate 22
is third distance D3, and the microelectromechanical infrared
sensing device 2 operates in a third absorbing rate mode. When the
reflecting plate 21 is at the third position, the second stoppers
25b are sandwiched between the substrate 20 and the reflecting
plate 21, and press against the substrate 20 and the reflecting
plate 21. At the moment, the distance D3' between the reflecting
plate 21 and the substrate 20 is substantially equal to the height
of the second stoppers 25b, such that the reflecting plate 21 dose
not contact the electrode layer 28 directly and can be separated
from the electrode layer 28
[0066] When the target temperature of the microelectromechanical
infrared sensing device 2 further changes to be T3
(T3>T2>T1), the controller 27 stops driving the voltage
source 26 (i.e. the voltage source 26 is turned off) so as to
control the reflecting plate 21 to move in the direction away from
the substrate 20 and then return back at the first position shown
in FIG. 14. At the moment, the distance between the reflecting
plate 21 and the sensing plate 22 is first distance D1 and the
microelectromechanical infrared sensing device 2 returns to the
first absorbing rate mode shown in FIG. 14.
[0067] As set forth above, the reflecting plate 21 can move between
the first position, the second position and the third position.
When the reflecting plate 21 is at the first position, the distance
between the reflecting plate 21 and the sensing plate 22 is first
distance D1. When the reflecting plate 21 is at the second
position, the first stoppers 25a are sandwiched by the substrate 20
and the reflecting plate 21, and press against the substrate 20 and
the reflecting plate 21. In this case, the distance between the
reflecting plate 21 and the sensing plate 22 is the second distance
D2, and the second distance D2 is greater than the first distance
D1. When the reflecting plate 21 is at the third position, the
second stoppers 25b are sandwiched by the substrate 20 and the
reflecting plate 21, and press against the substrate 20 and the
reflecting plate 21. In this case, the distance between the
reflecting plate 21 and the sensing plate 22 is the third distance
D3; the third distance D3 is greater than the second distance D2
and the second distance D2 is greater than the first distance D1.
The above mechanism can adjust the absorbing rate of the sensing
plate 22 with a view to prevent from the saturation of the readout
circuit and can enable the microelectromechanical infrared sensing
device 2 to have three operating points, which can effectively
increase the sensing range of the microelectromechanical infrared
sensing device 2. The microelectromechanical infrared sensing
device 2 can have more stoppers with different heights, such that
the microelectromechanical infrared sensing device 2 can have more
operating points so as to satisfy different measurement
requirements.
[0068] On the other hand, the microelectromechanical infrared
sensing device 2 can perform calculation via an algorithm according
to the target temperature and the operating points with a view to
obtain the best distance between the reflecting plate 21 and the
sensing plate 22 and then adjust the reflecting plate 21 according
to the calculation result. In this way, the sensing plate 22 can
absorb more thermal energy without incurring the saturation of the
readout circuit.
[0069] The embodiment just exemplifies the disclosure and is not
intended to limit the scope of the disclosure. Any equivalent
modification and variation according to the spirit of the
disclosure is to be also included within the scope of the following
claims and their equivalents.
[0070] Please refer to FIG. 17A, FIG. 17B, FIG. 18 and FIG. 19,
which are perspective views and cross-sectional views of a
microelectromechanical infrared sensing device 3 in accordance with
one embodiment of the disclosure respectively. FIG. 18 is the
cross-sectional view of the microelectromechanical infrared sensing
device 3 along line III-III in FIG. 17A. As shown in FIG. 17A, FIG.
17B and FIG. 18, the microelectromechanical infrared sensing device
3 includes a substrate 30, a reflecting plate 31, a sensing plate
32, a plurality of first supporting elements 33A, a plurality of
second supporting elements 33B, a plurality of fixation bases 34, a
plurality of stoppers 35, a voltage source 36, a controller 37 and
an electrode layer 38. The electrode layer 38 is disposed on the
substrate 30. The reflecting plate 31 includes an infrared
reflecting layer 311 and a dielectric material layer 312. Each of
the first supporting elements 33A includes a first connecting
portion A1, a first bending portion A2, a first supporting portion
A3 and a first anchor A4, and also has the layered structure
including an infrared reflecting layer 331A and a dielectric
material layer 332A. The sensing plate 32 includes an upper
infrared absorbing layer 321, an infrared sensing layer 323 and a
lower infrared absorbing layer 322. Each of the second supporting
elements 33B includes a second connecting portion B1, a second
bending portion B2, a second supporting portion B3 and a second
anchor B4, and also has the layered structure including an upper
infrared absorbing layer 331B, an infrared sensing layer 333B and a
lower infrared absorbing layer 332B. Similarly, the reflecting
plate 31 of the microelectromechanical infrared sensing device 3 is
suspended above the substrate 30 and the sensing plate 32 is
suspended above the reflecting plate 31. Accordingly, two thermal
insulation chambers (i.e. the first thermal insulation chamber H1
and the second thermal insulation chamber H2) can be formed between
the reflecting plate 31 and the substrate 30 and between the
reflecting plate 31 and the sensing plate 32 respectively, which
can significantly enhance the thermal insulation effect of the
microelectromechanical infrared sensing device 3 and reduce the
heat loss thereof.
[0071] The above elements are similar to the embodiments of FIG.
1.about.FIG. 12, so will not be described therein again. The
difference between this embodiment and the embodiments of FIG.
1.about.FIG. 12 is that the stoppers 35 are disposed on the
substrate 30, and the stoppers 35 and the substrate 30 may be made
of the same material. The above structure enables the
microelectromechanical infrared sensing device 3 to achieve similar
functions of the embodiments of FIG. 1.about.FIG. 12.
[0072] As shown in FIG. 18, when the controller 37 does not turn on
the voltage source 36, the reflecting plate 31 is at the position
closest to the sensing plate 32. At the moment, the reflecting
plate 31 is at a first position, as shown in FIG. 18. When the
reflecting plate 31 is at the first position, the distance between
the reflecting plate 31 and the sensing plate 32 is first distance
D1, and the microelectromechanical infrared sensing device 3
operates in a first absorbing rate mode.
[0073] As shown in FIG. 19, when the target temperature of the
microelectromechanical infrared sensing device 3 changes to be T1,
the controller 37 turns on the voltage source 36 to generate a
first control voltage V1 so as to control the reflecting plate 31
to move, from the first position away from the substrate 30, toward
the substrate 30. When the stoppers 35 contact the substrate 30,
the reflecting plate 31 stops moving and stays at a second
position, as shown in FIG. 19. In this case, the distance between
the reflecting plate 31 and the sensing plate 32 is second distance
D2 and the microelectromechanical infrared sensing device 3
operates in a second absorbing rate mode. When the reflecting plate
31 is at the second position, the stoppers 35 are sandwiched
between the substrate 30 and the reflecting plate 31, and press
against the substrate 30 and the reflecting plate 31. At the
moment, the distance between the reflecting plate 31 and the
substrate 30 is substantially equal to the height of the stoppers
35, such that the reflecting plate 31 can be separated from the
electrode layer 38 and does not contact the electrode layer 38. In
this case, the sensing plate 32 is furthest away from the
reflecting plate 31 (the infrared reflecting layer 311).
[0074] When the target temperature of the microelectromechanical
infrared sensing device 3 changes to be T2 (T2>T1), the
controller 37 stops driving the voltage source 36 (i.e. the voltage
source 36 is turned off) so as to control the reflecting plate 31
to move in the direction away from the substrate 30 and then return
back at the first position shown in FIG. 18. At the moment, the
distance between the reflecting plate 31 and the sensing plate 12
is first distance D1 and the microelectromechanical infrared
sensing device 3 returns to the first absorbing rate mode. The
above mechanism can prevent from the saturation of the readout
circuit, so the sensing accuracy of the microelectromechanical
infrared sensing device 3 can be improved and the sensing range of
the microelectromechanical infrared sensing device 3 can be also
increased.
[0075] The embodiment just exemplifies the disclosure and is not
intended to limit the scope of the disclosure. Any equivalent
modification and variation according to the spirit of the
disclosure is to be also included within the scope of the following
claims and their equivalents.
[0076] To sum up, according to the embodiments of the disclosure,
the reflecting plate of the microelectromechanical infrared sensing
device is suspended above the substrate and the sensing plate is
suspended above the reflecting plate, so two thermal insulation
chambers are formed. The structure can significantly enhance the
thermal insulation effect of the microelectromechanical infrared
sensing device and reduce the heat loss thereof. Thus, the
performance and the sensing accuracy of the microelectromechanical
infrared sensing device can be effectively enhanced.
[0077] According to the embodiments of the disclosure, the distance
between the reflecting plate and the substrate of the
microelectromechanical infrared sensing device can be adjusted via
the voltage source, and simultaneously change the distance between
the sensing plate and the reflecting plate in order to adjust the
absorbing rate of the microelectromechanical infrared sensing
device. Accordingly, the microelectromechanical infrared sensing
device can be operated in different absorbing rate modes, so can be
applied to the environments with different temperatures and prevent
from the saturation of the readout circuit. Thus, the sensing range
of the microelectromechanical infrared sensing device can be
greatly increased.
[0078] Moreover, according to the embodiments of the disclosure,
the microelectromechanical infrared sensing device has one or more
stoppers having different heights (e.g. the first stoppers and the
second stoppers). Therefore, the microelectromechanical infrared
sensing device is adjustable and has several operating points,
which further increases the sensing rage of the
microelectromechanical infrared sensing device.
[0079] Furthermore, according to the embodiments of the disclosure,
the sensing plate of the microelectromechanical infrared sensing
device has a symmetrical structure, which can balance the over
stress of the sensing plate so as to prevent from warpage and
deformation. Therefore, the distance between the sensing plate and
the reflecting plate can be precisely controlled, which can further
enhance the sensing accuracy of the microelectromechanical infrared
sensing device and simplify the manufacturing process thereof.
[0080] It will be apparent to those skilled in the art that various
modifications and variations can be made to the disclosed
embodiments. It is intended that the specification and examples be
considered as exemplary only, with a true scope of the disclosure
being indicated by the following claims and their equivalents.
* * * * *