Complete Specification
Field of the invention
This invention relates to pyrometric techniques for measuring surface temperatures of
objects based on 5 their thermal radiation signatures. More particularly, a preferred
embodiment of the present invention disclosed hereinunder outlines a significantly
improved infra-red sensing two-color pyrometer being characteristically equipped with
enhanced signal processing logic, trans-impedance amplifier circuit and wireless
communicability.
10
Background of the invention and description of related art
Viability and productivity of many industrial activities, both manufacturing as
well as quality control, and quality of resultant products or processes enjoined and
minimizing downtimes depend squarely on accurate measurement and monitoring of
15 temperature. It would not be incorrect to say in such parlance that temperature is the
most frequently measured physical quantity, second only to time. For example,
operating temperatures of kilns, furnaces, ovens, heating beds or the desired rate of
increase or decrease in temperatures in processes involving metals, plastics and
glass, and also chemosynthetic processes need critical monitoring. Hence, there is
20 an ever-existing need for suitable methodologies and apparatuses which effectively
allow accurate and precise measurement and monitoring of thermal profiles.
Contactless technologies for measurement and monitoring of thermal
profiles, particularly spectroscopy, have gained popularity in recent times due to their
ease of use, inexpensive electronic components, high efficacy, and ability of
25 integration in conjunction with preexisting industrial systems. Noncontact temperature
measurement using infrared-sensing technology (Opposed to emissivity-based
measurements or optical spectroscopy which depends on incandescence of the
target surface) is not new and has been successively implemented for quite some
time now, due to its high resolution, ability to target hazardous, high temperature, or
30 physically inaccessible objects, and absolutely no risk of contamination, interference,
or mechanical effect with the target of measurement. Remote-sensing thermometers
based on such technology are widely used in industry the world over.
However traditional infra-red sensing technologies for measurement and
monitoring of temperature are not without persisting lacunae that seek effective
35 resolution, such asa)
Measurement of temperature is affected by emissivity of target object;
Page 3 of 30
b) Materials of which emissivity is wavelength dependent cannot be subject to
these techniques for measurement of temperature;
c) Measurement of object temperature is not possible where dust, moisture,
smoke, and other contaminants are present in surrounding environment
5 which affect or preclude optical (infrared-optical) visibility of the target;
d) Measurement of object temperature is not possible where measuring object
is smaller than the spot size;
e) Measurement of temperature is not possible for real objects with unknown or
changing emissivities.
10
The inventor named herein credits the aforementioned persisting lacunae to
single color mode of referencing and proposes to address the same via adopting a
dual color approach for accurate and precise measurement of temperature which
carries all advantages of noncontact topical temperature measurement technologies
15 but none of their shortfalls. Prior art lists few scattered attempts at resolving the
issues listed above. For example, US4222663 (assigned to Pirelli Coordinamento
Pneumatici SpA), US6012840 and US6682216 (both assigned to University of
California), US4687344 (assigned to General Electric Co), 201617021069 (national
phase of EPO14150465.4, filed by Vesuvius Group S.A), 620/DELNP/2004 (filed by
20 Vesuvius Crucible Company), 1719/DELNP/2012 (filed by First Solar Inc) collectively
refer use of infrared sensors for temperature measurement, mechanisms for zone
centering, and removal of disturbances caused by the emission of gases from the
target of measurement.
Operational principles of two-color pyrometers (termed “ratio pyrometers”)
25 have been introduced as long since 1920 and commercially utilized around the year
1939. Moving forward, multiwavelength pyrometers are also available today which
provide for accurate temperature measurement even when the emissivity is unknown,
changing, and different at all wavelengths. However, very less work is seen to be
reported for increasing resolution, reliability, accuracy, and communicability of signal
30 output.
State-of-art therefore, does not list a single effective solution embracing all
considerations mentioned hereinabove, thus preserving an acute necessity-to-invent
for the present inventor/s who, as result of focused research, has come up with novel
solutions for resolving all needs once and for all. Work of the presently named
35 inventor/s, specifically directed against the technical problems recited hereinabove
Page 4 of 30
and currently part of the public domain including earlier filed patent applications, is
neither expressly nor impliedly admitted as prior art against the present disclosures.
Objectives
5 The present invention is identified in addressing at least all major deficiencies
of art discussed in the foregoing section by effectively addressing the objectives
stated under, of which-
It is a primary objective to provide a method, and device equipped with the
same, that allows infrared-sensing based noncontact measurement of temperature of
10 stationary as well as moving objects or any surfaces that cannot be reached or
physically touched.
It is another objective further to the aforesaid objective(s) that the device so
provided reliably combines functionalities of measurement, accumulation (logging)
and transmission of temperature data to the user.
15 It is another objective further to the aforesaid objective(s) that the method,
and device equipped with the same, so provided include improved logic for increased
resolution, reliability, and accuracy of signal output.
It is another objective further to the aforesaid objective(s) that the method,
and device equipped with the same, so provided includes means for seamless, or
20 real-time access and sharing of signal output to a connected or remote data logging
or processing facility.
It is another objective further to the aforesaid objective(s) that the method,
and device equipped with the same, so provided are not unnaturally complex or
expensive and lend favorably for procurement, installation, operations, and
25 maintenance within ambit of persons having average skill in the art.
The manner in which the above objectives are achieved, together with other
objects and advantages which will become subsequently apparent, reside in the
detailed description set forth below in reference to the accompanying drawings and
furthermore specifically outlined in the independent claim 1. Other advantageous
30 embodiments of the invention are specified in the dependent claims.
Summary
In general, the current disclosure is directed to an infrared-sensing two-color
pyrometer which is advantageously equipped with embedded software providing
35 improved processing logic for alternative mathematical manipulation of logged data, a
three-stage trans-impedance amplifier circuit for getting high speed and accurate data
Page 5 of 30
from sensor and furthermore adapted for utilization via inclusion of wireless
technology (Bluetooth / low energy Bluetooth) for access and sharing of signal output
to a connected or remote data logging or processing facility.
5 Brief description of drawings
The present invention is explained herein under with reference to the following
drawings, in which-
FIGURE 1 is a schematic illustration of the basic structural design of the infrared10
sensing two-color pyrometer proposed in the present invention.
FIGURE 2 is an A-A cross-sectional view of the structural design of the infraredsensing
two-color pyrometer proposed in the present invention.
15 FIGURE 3 is a ray diagram of the optical scheme arranged in the construction of the
infrared-sensing two-color pyrometer proposed in the present invention.
FIGURE 4 is a ray diagram showing the manner in which spot size calculations are to
be made in accordance with the disclosures hereof.
20
FIGURE 5 is a wireframe chart showing logic of operating the infrared-sensing twocolor
pyrometer proposed in the present invention.
FIGURE 6 is a graph showing a typical spectral response provided by the dual
25 sandwich detector used in the infrared-sensing two-color pyrometer proposed in the
present invention.
FIGURE 7 is a circuit diagram for the modified amplifier included in the infraredsensing
two-color pyrometer proposed in the present invention.
30
FIGURE 8 is a screen shot of Bluetooth android app. included in the infrared-sensing
two-color pyrometer proposed in the present invention.
The above drawings are illustrative of particular examples of the present invention but
35 are not intended to limit the scope thereof. The drawings are not to scale (unless so
stated) and are intended for use solely in conjunction with their explanations in the
Page 6 of 30
following detailed description. In above drawings, wherever possible, the same
references and symbols have been used throughout to refer to the same or similar
parts. Though numbering has been introduced to demarcate reference to specific
components in relation to such references being made in different sections of this
specification, 5 all components are not shown or numbered in each drawing to avoid
obscuring the invention proposed.
Key definitions and interpretations
Before undertaking the detailed description of the invention below, it may be
10 advantageous to set forth definitions of certain words or phrases used throughout this
patent document: the terms “include” and “comprise,” as well as derivatives thereof,
mean inclusion without limitation; the term “or” is inclusive, meaning and/or; the
phrases “associated with” and “associated therewith,” as well as derivatives thereof,
may mean to include, be included within, interconnect, with, contain, be contained
15 within, connect to or with, couple to or with, be communicable with, cooperate with,
interleave, juxtapose, be proximate to, be bound to or with, have, have a property of,
or the like; and the term “LCD” refers liquid crystal display.
Attention of the reader is now requested to the detailed description to follow which
20 narrates a preferred embodiment of the present invention and such other ways in
which principles of the invention may be employed without parting from the essence
of the invention claimed herein.
Detailed description
25 Principally, general purpose of the present invention is to assess disabilities and
shortcomings inherent to known systems comprising state of the art and develop new
systems incorporating all available advantages of known art and none of its
disadvantages. Accordingly, the disclosures herein are directed towards the
construction and operability of an improved infra-red sensing two-color pyrometer
30 being characteristically equipped with enhanced signal processing logic, and wireless
communicability.
A preferred exemplary embodiment of the present invention is described below,
which is of adequate nature to allow those of ordinary skill in the art to make and use
35 the invention claimed herein. It shall be evident however, that the disclosed subject
matter may be practiced without these exclusive exact details.
Page 7 of 30
Contactless pyrometers work on basis of the fact that objects emit thermal radiation in
an amount that directly corresponds to their own temperature and surface emissivity.
Two-color pyrometers involve measurement of thermal radiance at two different
wavelengths and inferring the temperature from the ratio of these spectral radiances.
Continuing 5 in this line, the preferred embodiment herein relates to a two-color
pyrometer that uses a dual detector assembly for measuring temperature of remote
target object/s by comparing infrared radiation levels from said object/s in two
wavelength bands (0.7 to 1.15 μm). Final temperature readings are based on the ratio
of the two signals corresponding to these bands. FIGURE 6 is a graph showing a
10 typical spectral response by way of example, provided by the dual sandwich detector
used in the infrared-sensing two-color pyrometer proposed in the present invention.
Assembly of the pyrometer head (01) proposed herein typically consists of a lens
(02), an aperture (03), a filter (04), a detector (05), and a signal processing unit (06).
15 Electrical / data connections (09) are provided to the unit (06) for powering and
interfacing the pyrometer head (01) with the user. As may be referred from the
accompanying FIGURE 1, the lens (02) collects infrared radiation (08) emitted by the
target object. The aperture (03) blocks all unwanted rays at its edges. The filter (04)
allows only desired spectral range to enter the detector. These rays then pass
20 through the detector (05) which converts said infrared radiation into electric signal.
Such signal is then made to pass through a signal processing unit (06) where it is
changed into standard output signal which can be conveyed by means (09) and
subsequently read on a remote display interface (not shown in FIGURE 1).
25 As may be referred from the accompanying FIGURE 2, internal construction of the
two-color pyrometer proposed herein principally involves a detector (05), being a
pyrometer photosensitive sensor in particular, which detects the amount of radiation
(flow of photons) emitted by the target object into the atmosphere. Signal captured by
the detector is passed to a processing unit which has a built-in microprocessor which
30 analyses the infrared signal to output the temperature read to a human interface such
as a LCD display unit. Typical spectral response of the detector (05) is shown in
Figure 7.
According to another aspect of the present invention, the detector (05) is a Silicon-
35 Silicon sandwich, in which one silicon photodiode is placed on top of the other, with
the photons of shorter wavelengths absorbed in the top silicon and the photons of
Page 8 of 30
longer wavelengths penetrating deeper, absorbed by the bottom photodiode. As may
be appreciated, dual sandwich detectors or two color detectors as employed herein
are mostly employed for remote temperature measurements. The temperature is
measured by taking the ratio of radiation intensities of two adjacent wavelengths and
comparing them with 5 the standard black body radiation curves. The advantages of
optical remote measurement have definitely made these devices the perfect match
for this type of measurements. They are independent of emissivity and unaffected by
contaminants in the field of view or moving targets. In addition, measurements of
targets out of the direct line of sight and the ability to function from outside RF/EMI
10 interference or vacuum areas are possible. They also have the advantages of
overcoming obstructed target views, blockages from sight tubes, channels or
screens, atmospheric smoke, steam, or dust, dirty windows as well as targets smaller
than field of view and/or moving within the field of view. These detectors can also be
used in applications where wide wavelength range of detection is needed.
15 Attention of the reader is requested to FIGURE 3, which is a ray diagram of the
optical scheme arranged in the construction of the infrared-sensing two-color
pyrometer proposed in the present invention. A laser targeting light is incorporated
within the sensor head assembly for assisting the user to correctly position the
pyrometer while taking temperature measurements. Accordingly, a pivotable beam
20 splitter (10) is interposed between the lens (02) and diaphragm (11) of the sensor
(12). An APC laser (13) is juxtaposed above the pivotable beam splitter (10) such that
at a time, the user may aim the sensor head assembly at the target accurately using
the laser, and then once path is ascertained, can measure temperature of the target
accurately. FIGURE 4 is a ray diagram showing the manner in which spot size
25 calculations are to be made in accordance with the disclosures hereof.
The present invention proposes to improve on existing two color pyrometers by first,
allowing the pyrometer to be selectively used in single or dual color modes at choice
of the user; and secondly, inclusion of enhanced mathematical algorithms for signal
30 processing and enhanced trans impedance amplifier circuit for accurate and precise
temperature readings.
Single color mode is best for measuring the temperature of target object in areas
where no sighting obstacle is present between the target object and the pyrometer.
35 Sighting obstacle can be any solid item, gaseous particles, smoke and dust etc. This
mode is very useful where target object completely fills the spot size. In all other
Page 9 of 30
cases, two color mode for temperature measurement of target object can be used
wherein the ratio of two separate and overlapping of infrared bands detected by two
dedicated sensors are used for pyrometry.
According 5 to another aspect of the present invention introduced in the foregoing
narration, the enhanced mathematical algorithms for signal processing are selected
amonga)
Brightness Temperature Calculation (single-color and two-color, any mode):
10
􀀁􀀂􀀃􀀄 =
14388.0
λ􀀄 ∗ ln ( 􀀑1
􀀒ℎ􀀔􀀕􀀔 􀀖􀀗􀀘􀀙􀀚􀀛_1)
− − − − − − − − − − − (􀀟)
􀀁􀀂􀀃􀀠 =
14388.0
λ􀀠 ∗ ln ( 􀀑2
􀀒ℎ􀀔􀀕􀀔 􀀖􀀗􀀘􀀙􀀚􀀛_2)
− − − − − − − − − − − − − (􀀢)
b) Real Temperature Calculation (two color pyrometer, single color mode):
􀀁􀀣􀀤􀀥􀀦 =
1
{( 1
􀀁􀀂􀀃􀀠
) + 􀀩 λ􀀠
14388.0􀀪 􀀛􀀙􀀫}
− − − − − − − − − − − − (􀀑)
15 c) Color Temperature Calculation (two color pyrometer, two-color mode):
􀀁􀀭􀀮􀀦􀀮􀀣 =
((􀀯􀀠 − 􀀯􀀄) ∗ 􀀁􀀂􀀃􀀄 ∗ 􀀁􀀂􀀃􀀠)
(􀀯􀀠 ∗ 􀀁􀀂􀀃􀀠 − 􀀯􀀄 ∗ 􀀁􀀂􀀃􀀄)
− − − − − − − − − − − − − (􀀰)
d) Real Temperature Calculation (two color pyrometer, two-color mode):
􀀁􀀣􀀤􀀥􀀦 =
􀀁􀀭􀀮􀀦􀀮􀀣
{1 + 􀀁􀀭􀀮􀀦􀀮􀀣 ∗ 􀀱
ln 􀀲􀀫􀀄
􀀫􀀠
􀀳
14388.0 ∗ 􀀩 1
λ􀀄
− 1
λ􀀠
􀀪
􀀴}
− − − − − − − − − − − − − − (􀀵)
20 e) Calculation Emissivity (two color pyrometer, two-color mode):
􀀵􀀶􀀷1 = 􀀸􀀹􀀺 􀀻
14388.0
λ􀀄
∗ 􀀩
1
􀀁􀀣􀀤􀀥􀀦
−
1
􀀁􀀂􀀃􀀄
􀀪􀀼 − − − − − − − − − − − − − − (F)
Page 10 of 30
According to yet another aspect of the present invention, the improved processing
logic includes an alternative mathematical manipulation of logged data. FIGURE 5 is
a flowchart depicting the logic underlying the selective deployment of mathematical
algorithms for signal processing included in the present invention.
5
Referring to FIGURE 5, it can be seen that signals (senor outputs) from dual sensor
(signal1 for one sensor and signal2 for second sensor), once generated, are
compared with each other. To ensure high accuracy in temperature measurement at
all times, the signal is assumed acceptable for the temperature calculation only if
10 comparison error is below 0.1%. Otherwise, the instance of operation is discarded
and reinitiated till this prerequisite is attained.
With continued reference to the FIGURE 5, it can be seen that the working
temperature range of the pyrometer proposed herein is divided into five segments,
15 and five Planck’s equations are used in each segment to arrive at accurate
temperature measurement. These equations are as under-
1) If Signal1 within Gain 1 : Gain 1 = 500 MΩ: the present inventors propose using
experimentally-validated values λ11 (Lambda1 for channel 1) and C11 (constant
20 1 for channel 1) within this signal range. Accordingly, it is required to replace the
values 􀀯􀀄 = 􀀯􀀄􀀄 and C1 = C11 in the above equations from (A) to (E) to arrive at
accurate temperature measurement.
2) If Signal1 within Gain 2 : Gain 2 = 70 MΩ the present inventors propose using
experimentally-validated values λ12 (Lambda 2 for channel 1) and C12 (constant
25 2 for channel 1) within this signal range. Accordingly, it is required to replace the
values λ1 = λ12 and C1 = C12 in the above equations from A to E for the
temperature calculations.
3) If Signal1 within Gain 3 : Gain 3 = 7 MΩ, the present inventors propose using
experimentally-validated values λ13 (Lambda 3 for channel 1) and C12 (constant
30 3 for channel 1) within this signal range. Accordingly, it is required to replace the
values λ1 = λ13 and C1 = C13 in the above equations from A to E for the
temperature calculations.
4) If Signal1 within Gain 4 : Gain 4 = 1 MΩ the present inventors propose using
experimentally-validated values λ14 (Lambda 4 for channel 1) and C12 (constant
35 4 for channel 1) within this signal range. Accordingly, it is required to replace the
Page 11 of 30
values λ1 = λ14 and C1 = C14 in the above equations from A to E for the
temperature calculations.
5) If Signal1 within Gain 5 : Gain 5 = 100 KΩ, the present inventors propose using
experimentally-validated values λ15 (Lambda 5 for channel 1) and C15 (constant
5 for channel 5 1) within this signal range. Accordingly, it is required to replace the
values λ1 = λ15 and C1 = C15 in the above equations from A to E for the
temperature calculations.
In formulae and their condition-specific selection proposed above, the inventors have
10 used 16 bit ADC (analog to digital convertor) to get signal (sensor output in digital)
from 0 to 65535. Same procedure is followed for Signal2 (signal of channel 2), therein
arriving at 5 equations for Signal2. Accordingly, various values of λ and C are
tabulated below at Table 1 below.
Gain level Signal 1 Signal 2
λ C λ C
Gain 1 0.992907 68423410 1.109773 6892437.485
Gain 2 1.002618 58425646 1.093598 8348301.208
Gain 3 0.981325 77738587 1.075243 10126258.14
Gain 4 0.958821 101570568 1.083951 9461745.258
Gain 5 0.945322 118152115 1.078491 9345474.265
Table 1
15
According to another aspect of the present invention, if the target object is moving or
it is smaller than the spot size, the amount of radiated energy is also reduced.
However, ratio of energies measured at different wavelengths is unaffected and
hence the measured temperature remains accurate.
20
In analogy to the preceding paragraph, energy emitted from a target is usually
reduced when target object is being blocked or some portion of the optical head is
blocked. This can occur when path of sight is partially blocked, or when any of the
sensors is subjected to dirt and/ or moisture, smoke accumulating on the lens
25 surface, or when dirt, smoke & moisture is present in the atmosphere between the
sensor and target. However, ratio of energies measured at different wavelengths is
unaffected and hence the measured temperature remains accurate.
Page 12 of 30
For extending the range, improving accuracy and response time for measurement of
temperature using the infrared-sensing two-color pyrometer proposed in the present
invention, the inventors named herein suggest incorporation of a modified three-stage
amplifier shown in FIGURE 7. This circuit is primarily intended for the using Si-Si
5 photo detector with cutoff wavelength = 1.0μm, but variations are intended to suit
other detectors common to art. The modified amplifier is characterized in having:
1) max transimpedance resistance (Gain) set to 500MΩ;
2) no expensive precise and high value resistors due to three stage setup,
which utilizes easy to find common art resistors with tolerance ±0.1% and
10 Max resistor value is 1MΩ;
3) five gain levels to therefore have good resolution especially on low
temperatures; and
4) does not sense the relatively small electric current (dark current) that flows
through the photo detector.
15
According to representative screenshots shown inFIGURE 8, wireless technology is
Bluetooth / low energy Bluetooth is integrated herein that allows access and sharing
of signal output of an infrared-sensing two-color pyrometer to a connected or remote
data logging or processing facility. In such configuration, the two-color pyrometer
20 proposed herein works as a slave to a client applet installed in a computational
system, such as a smart phone, which is the designated master.
The present invention has been reduced to practice by the inventor named herein.
Contribution of the present invention above prior art may be appreciated from Table
25 2, which is a head to head comparison of the pyrometer proposed herein to nearest
peers available in state of art.
Parameter Present invention
Nearest peers in state of art
Impac ISR 6 Advanced
Pyrospot DSR
54N
Temperature
Ranges
600°C - 1600°C
(100:1)
600°C - 1400°C (100:1) 600°C - 1400°C
(100:1)
800°C - 2500°C
(200:1)
700°C - 1800°C (200:1) 700°C - 1800°C
(200:1)
Spectral Cha1 and Cha2 : Cha1 : 0.9um Cha1 and Cha2 :
Page 13 of 30
Range 0.7....1.15 μm Cha2 : 1.05um 0.8....1.1 μm
Photodetector
Type
Si / Si Si / Si Si / Si
Emissivity
Range
0.1….1 adjustable
(for single color
mode)
0.05….1.00 adjustable
(for single color mode)
0.05….1.00
Emissivity slop 0.75….1.25 slop
adjustable (for two
color mode)
0.800….1.200 slop
adjustable (for two color
mode)
0.800….1.200
Accuracy 0.3% +1°C of
measured value
<1500°C: 0.3% of
reading in °C + 2°C
> 1500°C: 0.6% of
reading in °C
0.5 % of
measured value
in °C
Repeatability 0.1% of reading in
°C +1°C
0.15% of reading in °C +
1°C
0.1 % of
measured value
in °C
Response
Time
20msec. Adjustable
upto 10 sec
2 ms (with dynamic
adaption at low signal
levels); adjustable to
0.01 s; 0.05 s; 0.25 s; 1
s; 3 s; 10 s
5 ms (min.),
adjustable up to
100 s
Analog Output 4-20 mA or 0-20mA
or 0-10 V User
selectable
Adjustable 0 to 20 mA or
4 to 20 mA, linear
0/4 mA to 20 mA,
temperature
linear
Digital Output Bluetooth V2.0, RS-
232 & RS-485
(Isolated) User
Selectable
RS485
RS485
Power Supply 12V to 28V DC with
reverse voltage
protection
24 V DC ± 25%
24 V DC ± 25 %,
Page 14 of 30
Power
Consumption
Max. 2.5 Watt Max. 3 W
max. 1.5 W
(without load at
switching output)
Sighting Laser pilot light (PL)
or through the lens
sighting (TL)
Laser pilot light or
through the lens sighting
Laser pilot light
or Video Camera
Operating
temperature
range
0°C......70°C,
0°C.....200°C(with
cooling jacket)
0 to 65°C at housing
0 °C to 70 °C
Protection
class
IP 65 IP 65 IP 65
Table 2
The present invention has been reduced to practice by the inventors named herein in
form of two embodiments, which cater differentially for measure temperatures of the
object in 5 two ranges, a first range being between 600°C to 1600°C and a second
range being between 800°C to 2500°C. Commonly however and to further
embodiments foreseen and can be devised, the present invention is identified in
having at least the following salient featuresa)
Ability to be switched, at instance of the user, between 1-colour and 2-colour
10 modes for accurate non-contact measurement of temperature of the object;
b) Accurate and repeatable (precise) temperature measurement (in two
embodiments respectively identified by their ranges, a first range being
between 600°C to 1600°C and a second range being between 800°C to
2500°C) is possible as functioning of the device proposed herein does not
15 depend on, and is not affected by, emissivity of target object
c) Measurement of object temperature is possible where dust, moisture and other
contaminants are present in the surrounding environment.
d) Measurement of object temperature is possible even when the object of which
temperature is to be measured is moving or smaller than the spot size;
20 e) Pyrometer can be switched between 1-colour and 2-colour modes;
f) Measurement of object temperature is possible even when size of the object, of
which temperature is to be measured, is smaller than spot size;
g) Ability to compensate for emissivity variation, partially-filled fields of view, and
optical obstructions due to principle of its operations being two-color pyrometry;
h) Measurement of object temperature is possible
blocked or obscured
i) Ability to rapidly
mS with an accuracy of ± 0.
5
From the foregoing narration, an able technology for
noncontact measurement of temperature of
improved function and robust
art. The improved two10
environments involving
melting, rolling mills, rotary kilns
As will be realized further, the present invention is capable of various other
embodiments and that its several components and related details are capable of
15 various alterations, all without departing from the basic concept of t
invention. Accordingly, the foregoing description will be regarded as illustrative in
nature and not as restrictive in any form whatsoever. Modifications and variations
of the system and apparatus described herein will be obvio
the art. Such modifications and variations are intended to come within ambit of the
20 present invention, which is limited only by the appended claims
Dated this 03rd Day of
Duly constituted agent for the applicant,
25 ___________________
Rohit Deshpande
Advocate [MAH/4858/2012]
Tel: +91-20-30223654
30 To,
The Controller of Patents
The Patent Office at DELHI
Page 15 of 30
even when the spot is partially
obscured; and
measure high temperatures (within short response time of 20
ccuracy 0.3% +1°C of measured value) ranges up to 2500
infrared-sensing based
desired objects is thus provided with
serviceability than any of its closest peers in state
-color pyrometer has been satisfactorily tested in multiple usage
induction heating, annealing, welding, forging
kilns, crystal growing and so on.
obvious to those skilled in
claims.
July 2018
& Patent Agent [IN/PA-1389]
/ +91-9422944630 | Email: rdeshpande@skjlegal.com
2500oC
state-ofcolor
forging, sintering,
the present
us
Page 16 of 30
CLAIMS
We claim,
1) An improved system for accurate and fast non-contact measurement of
temperature of a remote object, comprising:
an infrared-5 sensing two-color pyrometer sensor head unit capable of being
aimed at the remote object for measurement of temperature of said
remote object by comparing levels of infrared radiation corresponding to
two wavelength bands selected in the range between 0.7 to 1.15 μm
emitted by said remote object; and
10 a remote device arranged to interact, via communications means, with the
infrared-sensing two-color pyrometer sensor head unit to thereby allow,
via an human-machine interface, a user to undertake at least one among
initialization, operations, and logging temperature readings measured by
said infrared-sensing two-color pyrometer sensor head unit
15 Characterized in that the improvements lie in the system having:
Ability of being operated as per choice of the user by switching, by means of
a control circuit, between single color and two color modes of operation
to thereby compensate for emissivity variation, partially-filled fields of
view, and optical obstructions incidental while measuring the temperature
20 of said remote object;
Ability, by means of improved optics, to measure temperature even when
measurement spot is larger than size of the object, of which temperature
is to be measured; and
Enhanced logic for signal amplification and processing to thereby achieve
25 extended measurement range from 600°C to 2500°C, enhanced
accuracy in measurement of 0.3% +1°C of measured value, precision of
less than 0.1% variance in readings, and short response time adjustable
between 20 milliseconds to 10 seconds for non-contact measurement of
temperature of the remote object.
30
2) The improved system for accurate and fast non-contact measurement of
temperature of a remote object as claimed in claim 1, wherein the infraredsensing
two-color pyrometer sensor head unit is characterized in having:
a photosensitive Si / Si sandwich photodetector to measure energy radiated
35 by the target, said detector having cutoff wavelength of 1.0μm;
Page 17 of 30
optics, being a set of lenses in particular, interposed linearly along the path of
light between the target and the Si / Si sandwich photodetector to focus
said radiant energy on the photosensitive sensor;
a filter set comprising at least a plurality of filters interposed linearly along the
5 path of light between the optics and the Si / Si sandwich photodetector
for limiting the spectral range of the radiant energy passing therethrough;
and
optionally, a wireless transreceiver unit for broadcasting, over the air, signal
output of the infrared-sensing two-color pyrometer sensor head unit
10
3) The improved system for accurate and fast non-contact measurement of
temperature of a remote object as claimed in claims 1 and 2, wherein the remote
device is a common art interactively-communicable computational unit
comprising:
15 a signal amplification and computational module, the latter including
processing logic, arranged in combination to receive, condition, and
thereafter process signal input measured by the infrared-sensing twocolor
pyrometer sensor head unit, therein particularly corresponding to
the spectral ranges limited by each member among the filter set; and
20 a set including at least one each of a processor, memory, input device, visual
display, and a wireless communications unit arranged to be under control
of a user whereby said user may interact wirelessly with the infraredsensing
two-color pyrometer sensor head unit and thereby undertake at
least one among initialization, operations, and logging temperature
25 readings measured by said infrared-sensing two-color pyrometer sensor
head unit.
4) The Error! Reference source not found. as claimed in claim 1, wherein the
enhanced signal processing logic is a computer-implemented routine the
30 execution of which results in subjecting signal output of the infrared-sensing twocolor
pyrometer sensor head unit to mathematical calculation using one equation
selected among:
a) 􀀁􀀂􀀃􀀄 = 􀀄􀀾􀀿􀁀􀁀.􀁁
􀁂􀁃∗􀁄􀁅 ( 􀁆􀁃
􀁇􀁈􀁉􀁊􀁉 􀁋􀁌􀁍􀁎􀁏􀁐_􀁃)
; And
􀀁􀀂􀀃􀀠 =
14388.0
λ􀀠 ∗ ln ( 􀀑2
􀀒ℎ􀀔􀀕􀀔 􀀖􀀗􀀘􀀙􀀚􀀛_2)
Page 18 of 30
when calculating temperature of the remote object using its brightness
while using either among the single color and two color modes of
implementation;
b) 􀀁􀀣􀀤􀀥􀀦 = 􀀄
{( 􀁃
􀁒􀁓􀁔􀁕
)􀁖􀀲 􀁗􀁕
􀁃􀁘􀁙􀁚􀁚.􀁛􀀳􀀦􀁜􀁝}
5 when calculating real temperature of the remote object while using the
single color mode of implementation;
c) 􀀁􀀭􀀮􀀦􀀮􀀣 = ((􀁞􀁕􀁟􀁞􀁃)∗􀁠􀁡􀀣􀁃∗􀁠􀁡􀀣􀁕)
(􀁞􀁕∗􀁠􀁡􀀣􀁕􀁟􀁞􀁃∗􀁠􀁡􀀣􀁃)
when calculating color temperature of the remote object while using the
two-color mode of implementation;
d) 􀀁􀀣􀀤􀀥􀀦 = 􀁠􀁢􀁉􀁐􀁉􀁔
{􀀄􀁖􀁠􀁢􀁉􀁐􀁉􀁔∗􀁣
􀁤􀁥􀀩􀁦􀁃
􀁦􀁕
􀀪
􀁃􀁘􀁙􀁚􀁚.􀁛∗􀀩 􀁃
􀁗􀁃
􀁧 􀁃
􀁗􀁕
􀀪
􀁨}
10
when calculating real temperature of the remote object while using the twocolor
mode of implementation
e) 􀀵􀀶􀀷1 = 􀀸􀀹􀀺 􀁪􀀄􀀾􀀿􀁀􀁀.􀁁
λ􀁃
∗ 􀀲 􀀄
􀁠􀁔􀁫􀁏􀁐
− 􀀄
􀁠􀁡􀀣􀁃
􀀳􀁬
when calculating temperature of the remote object based on its emissivity
15 while using the two-color mode of implementation
Where h = Planck’s constant 6.626 * 10^(-34) J*s; c = speed of light
2.997925 * 10^(8) m/sec; λ = wavelength; k = Boltzmann’s constant
1.381*10(-23) J/K; and T = Temperature(K)
20
5) The improved system for accurate and fast non-contact measurement of
temperature of a remote object as claimed in claim 4, wherein the value of λ is
selected among predetermined values depending on percentage of signal
strength read from the infrared-sensing two-color pyrometer sensor head unit,
25 therein particularly for:
For Signal 1, corresponding to the first from first among the two wavelength
bands selected for measurement:
a) 0.992907 if the signal value is within gain 1, where gain 1 is 500 MΩ;
b) 1.002618 if the signal value is within gain 2, where gain 2 is 70 MΩ;
30 c) 0.981325 if the signal value is within gain 3, where gain 3 is 7 MΩ;
d) 0.958821 if the signal value is within gain 4, where gain 4 is 1 MΩ;
and
e) 0.945322 if the signal value is within gain 5, where gain 5 is 100 KΩ.
Page 19 of 30
For Signal 2, corresponding to the second from first among the two
wavelength bands selected for measurement:
a) 1.109773 if the signal value is within gain 1, where gain 1 is 500 MΩ;
b) 1.093598 if the signal value is within gain 2, where gain 2 is 70 MΩ;
c) 1.075243 5 if the signal value is within gain 3, where gain 3 is 7 MΩ;
d) 1.083951 if the signal value is within gain 4, where gain 4 is 1 MΩ;
and
e) 1.078491 if the signal value is within gain 5, where gain 5 is 100 KΩ.
10 6) The improved system for accurate and fast non-contact measurement of
temperature of a remote object as claimed in claim 4, wherein the values of C is
selected among predetermined values depending on percentage of signal
strength read from the infrared-sensing two-color pyrometer sensor head unit,
therein particularly for:
15 For Signal 1, corresponding to the first from first among the two wavelength
bands selected for measurement:
a) 68423410 if the signal value is within gain 1, where gain 1 is 500 MΩ;
b) 58425646 if the signal value is within gain 2, where gain 2 is 70 MΩ;
c) 77738587 if the signal value is within gain 3, where gain 3 is 7 MΩ;
20 d) 101570568 if the signal value is within gain 4, where gain 4 is 1 MΩ;
and
e) 118152115 if the signal value is within gain 5, where gain 5 is 100
KΩ .
For Signal 2, corresponding to the second from first among the two
25 wavelength bands selected for measurement:
a) 6892437.485 if the signal value is within gain 1, where gain 1 is 500
MΩ;
b) 8348301.208 if the signal value is within gain 2, where gain 2 is 70
MΩ;
30 c) 10126258.14 if the signal value is within gain 3, where gain 3 is 7
MΩ;
d) 9461745.258 if the signal value is within gain 4, where gain 4 is 1
MΩ; and
e) 9345474.265 if the signal value is within gain 5, where gain 5 is 100
35 KΩ.
Page 20 of 30
7) The improved system for accurate and fast non-contact measurement of
temperature of a remote object as claimed in claims 4 to 6, wherein the enhanced
signal processing logic, in case of using the two-color mode of implementation,
allows implementation of the step of selecting the mathematical formula only in
the 5 condition that ratio between the radiation measurements corresponding to
Signal 1 and Signal 2 is greater than 0.1 to thereby ensure accuracy of ± 0.3%
+1°C of measured value of temperature.
8) The improved system for accurate and fast non-contact measurement of
10 temperature of a remote object as claimed in claims 1 and 2, wherein the spot
size is a topographical point selected on surface of a remote object and the ratio
between distance of said remote object from the infrared-sensing two-color
pyrometer sensor head unit and spot size is calculated particularly as:
for range of measurement between 600°C to 1600°C:
15 a) as 1/100th of the manufactured working distance of the optics;
b) at least 8mm if the manufactured working distance of the optics is infinity;
and
c) 7mm if the manufactured working distance of the optics is equal to size of
lens opening aperture of the infrared-sensing two-color pyrometer sensor
20 head unit.
for range of measurement selected is between 800°C to 2500°C, the distance
to spot size ratio is calculateda)
as 1/200th of the manufactured working distance of the optics;
b) at least 5mm if the manufactured working distance of the optics is infinity;
25 and
c) 4mm if the manufactured working distance is equal to size of lens
opening aperture of the infrared-sensing two-color pyrometer sensor
head unit.
30 9) The improved system for accurate and fast non-contact measurement of
temperature of a remote object as claimed in claims 1, 2 and 4, wherein the
enhanced signal amplification logic is provided by means of a three-stage
amplifier circuit represented in FIGURE 7 which is included in either among the
infrared-sensing two-color pyrometer sensor head unit and the remote device,
35 said circuit characterized in having:
a) max transimpedance resistance gain
bifurcated into five levels
7 MΩ, 1
processing logic;
5 b) common art resistors
1MΩ instead of
c) no response to dark current
photodetector
10 10) The improved system for accurate and fast non temperature of a remote object as claimed in
and particularly