Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.
-
Upload
melchiorre-forte -
Category
Documents
-
view
223 -
download
3
Transcript of Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.
![Page 1: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/1.jpg)
Termometro auricolare
U.S. Patent 4.797.840 by Jacob Fraden
![Page 2: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/2.jpg)
Sensore di radiazione IR• Materiale piroelettrico: presentano una
polarizzazione dielettrica spontanea che varia con la temperatura (ad esempio da un sottile strato di Tantalato di Litio con elettrodi metallici depositati sulle due facce).
• Quando la temperatura del sensore varia anche la polarizzazione (e la carica) del condensatore, producendo una debole corrente alternata (dell’ordine di 10-12÷ 10-10 A).
![Page 3: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/3.jpg)
Circuiti per la lettura
Chargegeneratorq = KT
Rp Cp Cc Ca
+iAmplifier = 0 o
-
R = Ra Rp /(Ra+ Rp ) » Ra
C = Cp + Cc + Ca
Charge
generatoris = dq/dt=KdT/dt
is
C RiC
iR+
ia= 0
o
-
Ra
![Page 4: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/4.jpg)
€
iS = iC + iR
v0 = vC =1
C
⎛
⎝ ⎜
⎞
⎠ ⎟ iCdt∫
iS − iR =Cdv0
dt
⎛
⎝ ⎜
⎞
⎠ ⎟=K
dT
dt−v0
R
V0(s)
T(s)=KSsτ
sτ +1
KS=K/C sensibilità, V/°C
=RC costante di tempo C KS
![Page 5: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/5.jpg)
R
+ FET
Sensore piroelettrico
C
is
isRisC
dqs/ dt = is = K dT/dt
L’amplificatore trasferisce la carica generata dal sensore piroelettrico alla capacità C
€
v0 = −1
CKdT
dtt∫ dt = −
K
CdT
t∫
![Page 6: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/6.jpg)
Schema termometro
![Page 7: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/7.jpg)
Sensore piroelettrico
Polyvinylidene fuoride (PVDF)
5-100 micron
![Page 8: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/8.jpg)
Guida per la radiazione IR
![Page 9: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/9.jpg)
Circuito di lettura
![Page 10: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/10.jpg)
SegnaleOtturatore: si apre in 5-25 ms, tempi di apertura 200 ms
€
Vir = f (Ta )(TS4 −Ta
4 )
€
f (Ta ) = a0 + a1T + a2T2 + a3T
3 + ....
€
TS = (Vir / f (Ta ) +Ta4 )
14
![Page 11: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/11.jpg)
Circuiti di calibrazionePiezoelettricità
Piroelettricità
![Page 12: Termometro auricolare U.S. Patent 4.797.840 by Jacob Fraden.](https://reader035.fdocument.pub/reader035/viewer/2022062319/5542eb58497959361e8c33be/html5/thumbnails/12.jpg)
Ulteriore applicazione