Radiant energy – Calibration or standardization methods
Reexamination Certificate
2002-01-31
2003-06-10
Gutierrez, Diego (Department: 2878)
Radiant energy
Calibration or standardization methods
C250S330000, C250S347000
Reexamination Certificate
active
06576892
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to infrared imaging devices, and more particularly, to an infrared imaging device, including an infrared detector, a view switching function, and a sensitivity correction function.
2. Description of the Related Art
An infrared imaging device is, for instance, mounted on an airplane and used for recognizing an objective body on the ground or in the air. It has been required that an image taken by the infrared imaging device be of high quality and that the infrared imaging device be small and lightweight.
In addition, the infrared imaging device requires a view switching function and a sensitivity correction function.
Plural kinds of magnification lenses having different magnifications are switched on an optical axis by the view switching function of the infrared imaging device. Generally, the objective body is initially detected by a magnification lens having a low magnification. And then, the magnification lens having a low magnification is replaced by a magnification lens having a high magnification by the view switching function and thereby the objective body is recognized and distinguished.
Furthermore, dispersions of respective sensitivities of a great number of pixels comprising infrared detect elements are detected and corrected electrically by the sensitivity correction function. The quality of the image taken by the infrared imaging device may be improved by implementing the sensitivity correction as required.
FIG. 1A
is a plan view of a related infrared imaging device
10
.
FIG. 1B
is a section taken on line a—a in FIG.
1
A.
FIG. 1C
is a section taken on line b—b in FIG.
1
A.
FIG. 2
is a schematic illustration of the related infrared imaging device
10
. Referring to
FIGS. 1A through 1C
and
2
, the infrared imaging device
10
includes a housing
11
, an objective lens
12
, a varying magnification lens
13
, an infrared detector
14
, a view switching mechanism
20
, and a sensitivity correction mechanism
30
. The objective lens
12
, the varying magnification lens
13
, and the infrared detector
14
are arranged in the line of an optical axis
15
. The objective lens
12
is mounted on an upper surface of the housing
11
. The varying magnification lens
13
, the infrared detector
14
, the view switching mechanism
20
, and the sensitivity correction mechanism
30
are provided inside of the housing
11
.
As shown in
FIG. 2
, an infrared light
16
radiated from the objective body is received by the objective lens
12
and the varying magnification lens
13
and reaches the infrared detect element
50
in the infrared detector
14
. As a result, the infrared light
16
is focused into an image of the objective body on the infrared detect element
50
. An output from the infrared detect element
50
is amplified and transmitted to the indication part
60
. The image formed by the infrared imaging device is projected on the indication part
60
.
The view switching mechanism
20
is supported in a state where the view switching mechanism
20
can be moved in the X
1
-X
2
direction as shown in FIG.
1
A. The view switching mechanism
20
includes a mount board
22
, a motor
23
and a crank mechanism
24
. The varying magnification lens
13
having a low magnification and the varying magnification lens
21
having a high magnification are mounted on the mount board
22
. The mount board
22
can be moved in the X
1
-X
2
direction by using the crank mechanism
24
driven with the motor
23
.
The sensitivity correction mechanism
30
has a sensitivity correction base
33
and a motor
34
. The sensitivity correction base
33
having a fan shape is supported by an output shaft
32
of a gear mechanism
31
. The gear mechanism
31
is driven by the motor
34
. A standard heat source board
35
of a normal temperature side and a mirror
36
as a standard heat source board of a low temperature side are provided on a lower surface of the sensitivity correction base
33
. The sensitivity correction base
33
is arranged in a space
40
between the varying magnification lens
13
and the infrared detector
14
.
The infrared detect element
50
is provided inside of the infrared detector
14
. The infrared detect element
50
has a structure in which a great number of pixels are arranged in a matrix shape and is cooled cryogenically by a cooler not shown in
FIGS. 1A through 1C
and
2
.
Sensitivity correction is implemented by utilizing the temperature of the infrared detect element
50
itself and a normal temperature. The motor
34
is driven and the sensitivity correction base
33
is rotated in the A-B direction shown in
FIG. 1A
by using the gear mechanism
31
. First, the outputs of the respective pixels of the infrared detect element
50
are measured when the mirror
36
is moved onto the optical axis
15
, and then the outputs are saved in digital form. Next, the standard heat source board
35
of the normal temperature side is moved onto the optical axis
15
. Outputs of the respective pixels of the infrared detect element
50
are measured when an infrared light radiated from the standard heat source board
35
is received by the infrared detector
14
, and then the outputs are saved in digital form. The sensitivity correction is implemented by reading out the saved information and calculating a correction coefficient. When the mirror
36
faces the infrared detector
14
, the infrared detect element
50
is reflected in the mirror
36
. Since the infrared detect element
50
is cooled cryogenically as described above, a cryogenically cooled infrared light radiated from the infrared detect element
50
is reflected by the mirror
36
and received at the infrared detect element
50
.
The view switching is implemented by driving the motor
23
and moving the mount board
22
with the crank mechanism
24
, and thereby the varying magnification lens
13
is displaced by a magnification lens
21
having a high magnification.
However, two motors are needed for the conventional infrared imaging device
10
because the conventional infrared imaging device
10
has the view switching mechanism
20
and the sensitivity correction mechanism
30
provided independently. Hence, it is difficult to miniaturize and reduce the weight of the infrared imaging device
10
.
In addition, the sensitivity correction mechanism
30
has a structure in which the sensitivity correction base
33
is arranged in the narrow space
40
between the varying magnification lens
13
and the infrared detector
14
. Therefore, it is difficult to provide a standard heat source having the sensitivity correction base
33
on which a peltier device is equipped. Rather, the standard heat source board
35
and the mirror
36
as the standard heat source board of a low temperature are provided on the sensitivity correction base
33
in the conventional infrared imaging device
10
.
Accordingly, two kinds of standard temperature infrared lights, namely the infrared light radiated from the standard heat source board
35
and the infrared light cooled cryogenically, radiate to the infrared detect element
50
. The difference of temperatures between the two kinds of standard temperature infrared lights provided to the infrared detect element
50
is 100 centigrade or more. Meanwhile, the objective body of the infrared imaging device
10
generates heat, and the objective body is detected with the infrared imaging device
10
by comparing a temperature in a background source with the objective body.
Furthermore, the sensitivity of the infrared detect element
50
is not proportional to the energy of the infrared light generated by the objective body. Rather, the infrared light has a property in that a secondary curved line can be drawn, wherein the energy of the infrared light is defined as the horizontal axis and the sensitivity of the infrared detect element
50
is defined as the vertical axis. Therefore, since the difference of temperatures of two kinds of standard temperature infrared light sources p
Kawase Hiroshi
Maruyama Tsutomu
Murakado Kenichi
Nameki Eiji
Shimomae Hiroki
Fujitsu Limited
Gutierrez Diego
Smith R. Alexander
Staas & Halsey , LLP
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