EP0419583A1 - Improvements in and relating to pyroelectric detectors - Google Patents
Improvements in and relating to pyroelectric detectorsInfo
- Publication number
- EP0419583A1 EP0419583A1 EP89910879A EP89910879A EP0419583A1 EP 0419583 A1 EP0419583 A1 EP 0419583A1 EP 89910879 A EP89910879 A EP 89910879A EP 89910879 A EP89910879 A EP 89910879A EP 0419583 A1 EP0419583 A1 EP 0419583A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- pyroelectric
- pyroelectric material
- detector
- bias
- sensitivity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000463 material Substances 0.000 claims abstract description 37
- 238000000034 method Methods 0.000 claims abstract description 9
- 230000035945 sensitivity Effects 0.000 claims abstract description 9
- 230000005669 field effect Effects 0.000 claims description 7
- 238000005513 bias potential Methods 0.000 claims description 2
- 230000001419 dependent effect Effects 0.000 claims description 2
- 230000005855 radiation Effects 0.000 description 5
- 230000003321 amplification Effects 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/003—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using pyroelectric elements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/10—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors
- G01J5/20—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
- G01J5/22—Electrical features thereof
- G01J5/24—Use of specially adapted circuits, e.g. bridge circuits
Definitions
- the present invention relates to a pyroelectric detector and to a method of improving the sensitivity of the pyroelectric material in the pyroelectric detector.
- a typical known pyroelectric detector is illustrated schematically in Figure 1, in which a temperature change in a pyroelectric material P will generate a voltage change on the gate of a junction field effect transistor J that can be measured at its output 2 with suitable circuitry.
- Line 3 is the supply voltage line to the transistor J and line 1 is at ground.
- a resistor R arranged in parallel with the pyroelectric material P has the dual function of controlling the electrical time constant of the device and of correctly biasing the gate of the transistor J.
- An objective of the present invention is to provide an improved pyroelectric detector to that illustrated in Figure 1.
- a method of improving the sensitivity of a pyroelectric material in a pyroelectric detector comprising applying a bias across the pyroelectric material to enhance the sensitivity of the pyroelectric material above that obtained when no bias is applied across the pyroelectric material.
- a pyroelectric detector comprising a circuit arrangement incorporating a pyroelectric material, the arrangement being such that when in operation the pyroelectric material is subjected to an applied bias potential, the output of the pyroelectric detector for a temperature change in the pyroelectric material being dependent upon the strength of the bias applied across the pyroelectric material.
- the pyroelectric material is electrically coupled to the gate of a junction field effect transistor whereby a temperature change in the pyroelectric material generates a voltage change at the gate of the junction field effect transistor.
- the junction field effect transistor can be omitted or replaced by an alternative component as for example a MOSFET, a bipolar transistor or a. resistor if a sufficiently high radiation level were being measured.
- a resistor is arranged in series with the pyroelectric material the resistor being provided between the pyroelectric material and a low or zero voltage line.
- Figure 1 is a schematic illustration of a known pyroelectric detector
- Figure 2 is a schematic illustration of a pyroelectric detector according to an embodiment of the present invention.
- FIG. 2 An improved radiation detector is shown in Figure 2.
- a non- signal side (lead 4) of the pyroelectric element P is taken to an external high voltage source (not shown) so that the pyroelectric material is operated under a bias field.
- the pyroelectric material used should be one having properties which are enhanced under these conditions and greater sensitivity is obtained.
- a detector structure may be fabricated, for example, in which the pyroelectric material P is a modified lead zirconate ceramic, J is a field effect transistor and R is 10 10 ohms.
- the device area can be approximately 1mm 2 and its thickness approximately 50 ⁇ m.
- the pyroelectric material element P may be only one of a multiplicity of similar elements arranged as a one or two dimensional array.
- the transistor J serves as a convenient impedance converter. It could be omitted or replaced by an alternative component eg. a MOSFET, a bipolar transistor or even a resistor if sufficiently high radiation level are to be measured.
- the resistor R may not be required or may be built into the material of P depending on the bias requirements of the transistor J.
Abstract
Détecteur pyroélectrique et procédé permettant d'accroître la sensibilité du matériau pyroélectrique dans ledit détecteur pyroélectrique. Le procédé consiste à appliquer une haute tension de polarisation indépendante à travers le matériau pyroélectrique pour élever la sensiblité dudit matériau à un niveau au-dessus de celui que l'on obtient lorsque aucune polarisation n'est appliquée à travers le matériau polyélectrique.Pyroelectric detector and method for increasing the sensitivity of the pyroelectric material in said pyroelectric detector. The method includes applying a high independent bias voltage across the pyroelectric material to raise the sensitivity of said material to a level above that obtained when no bias is applied through the polyelectric material.
Description
IMPROVEMENTS IN AND RELATING TO PYROELECTRIC
DETECTORS
The present invention relates to a pyroelectric detector and to a method of improving the sensitivity of the pyroelectric material in the pyroelectric detector.
A typical known pyroelectric detector is illustrated schematically in Figure 1, in which a temperature change in a pyroelectric material P will generate a voltage change on the gate of a junction field effect transistor J that can be measured at its output 2 with suitable circuitry. Line 3 is the supply voltage line to the transistor J and line 1 is at ground. A resistor R arranged in parallel with the pyroelectric material P has the dual function of controlling the electrical time constant of the device and of correctly biasing the gate of the transistor J.
An objective of the present invention is to provide an improved pyroelectric detector to that illustrated in Figure 1.
According to a first aspect of the present invention there is provided a method of improving the sensitivity of a pyroelectric material in a pyroelectric detector, the method comprising applying a bias across the pyroelectric material to enhance the sensitivity of the pyroelectric material above that obtained when no bias is applied across the pyroelectric material.
According to a second aspect of the present invention there is provided a pyroelectric detector comprising a circuit arrangement incorporating a pyroelectric material, the arrangement being such that when in operation the pyroelectric material is subjected to an applied bias potential, the output of the pyroelectric detector for a
temperature change in the pyroelectric material being dependent upon the strength of the bias applied across the pyroelectric material.
In one embodiment the pyroelectric material is electrically coupled to the gate of a junction field effect transistor whereby a temperature change in the pyroelectric material generates a voltage change at the gate of the junction field effect transistor. In other embodiments the junction field effect transistor can be omitted or replaced by an alternative component as for example a MOSFET, a bipolar transistor or a. resistor if a sufficiently high radiation level were being measured.
In another embodiment a resistor is arranged in series with the pyroelectric material the resistor being provided between the pyroelectric material and a low or zero voltage line.
The invention will be described further, by way of example, with reference to the accompanying drawings in which:-
Figure 1 is a schematic illustration of a known pyroelectric detector; and,
Figure 2 is a schematic illustration of a pyroelectric detector according to an embodiment of the present invention.
An improved radiation detector is shown in Figure 2. A non- signal side (lead 4) of the pyroelectric element P is taken to an external high voltage source (not shown) so that the pyroelectric material is operated under a bias field. The pyroelectric material used should be one having properties which are enhanced under these conditions and greater sensitivity is obtained.
A detector structure may be fabricated, for example, in which the pyroelectric material P is a modified lead zirconate ceramic, J is a
field effect transistor and R is 1010 ohms. The device area can be approximately 1mm2 and its thickness approximately 50μm. When in the configuration of Figure 1 and placed in front of a radiation source modulated at 200 HZ a signal level of 50 mV is observed after amplification. When reconfigured to match Figure 2 with the line 4 at + 150 volts, the output level rises to 75 mV under the same conditions of radiation input and amplification.
Although the invention has been described above in relation to the embodiment shown in Figure 2 it will be understood that other embodiments which fall within the scope of the invention would be understood to a person skilled in the art.
For example, the pyroelectric material element P may be only one of a multiplicity of similar elements arranged as a one or two dimensional array.
It will also be appreciated that the transistor J serves as a convenient impedance converter. It could be omitted or replaced by an alternative component eg. a MOSFET, a bipolar transistor or even a resistor if sufficiently high radiation level are to be measured.
The resistor R may not be required or may be built into the material of P depending on the bias requirements of the transistor J.
Claims
1. A method of improving the sensitivity of a pyroelectric material in a pyroelectric detector, the method comprising applying a bias across the pyroelectric material to enhance the sensitivity of the pyroelectric material above that obtained when no bias is applied across the pyroelectric material.
2. A pyroelectric detector comprising a circuit arrangement incorporating a pyroelectric material, the arrangement being such that when in operation the pyroelectric material is subjected to an applied bias potential, the output of the pyroelectric detector for a temperature change in the pyroelectric material being dependent upon the strength of the bias applied across the pyroelectric material.
3. A pyroelectric detector as claimed in claim 2 wherein the pyroelectric material is electrically coupled to the gate of a junction field effect transistor whereby a temperature change in the pyroelectric material generates a voltage change at the gate of the junction field effect transistor.
4. A pyroelectric detector as claimed in claim 2 or 3 wherein a resistor is arranged in series with the pyroelectric material, the resistor being provided between the pyroelectric material and a low or zero voltage line.
5. A method of improving the sensitivity of a pyroelectric material in a pyroelectric detector, the method being substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.
6. A pyroelectric detector substantially as hereinbefore described with reference to Figure 2 of the accompanying drawing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8822693 | 1988-09-28 | ||
| GB8822693A GB2223571B (en) | 1988-09-28 | 1988-09-28 | Improvements in or relating to pyroelectric detectors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0419583A1 true EP0419583A1 (en) | 1991-04-03 |
Family
ID=10644336
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP89910879A Withdrawn EP0419583A1 (en) | 1988-09-28 | 1989-09-21 | Improvements in and relating to pyroelectric detectors |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0419583A1 (en) |
| JP (1) | JPH03502735A (en) |
| GB (1) | GB2223571B (en) |
| WO (1) | WO1990003556A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7545622B2 (en) | 2006-03-08 | 2009-06-09 | Wispry, Inc. | Micro-electro-mechanical system (MEMS) variable capacitors and actuation components and related methods |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3453887A (en) * | 1967-02-08 | 1969-07-08 | Corning Glass Works | Temperature change measuring device |
| US4032783A (en) * | 1975-06-09 | 1977-06-28 | Hughes Aircraft Company | Pyroelectric radiation sensor and imaging device utilizing same |
-
1988
- 1988-09-28 GB GB8822693A patent/GB2223571B/en not_active Expired - Lifetime
-
1989
- 1989-09-21 JP JP1510010A patent/JPH03502735A/en active Pending
- 1989-09-21 WO PCT/GB1989/001111 patent/WO1990003556A1/en not_active Application Discontinuation
- 1989-09-21 EP EP89910879A patent/EP0419583A1/en not_active Withdrawn
Non-Patent Citations (1)
| Title |
|---|
| See references of WO9003556A1 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7545622B2 (en) | 2006-03-08 | 2009-06-09 | Wispry, Inc. | Micro-electro-mechanical system (MEMS) variable capacitors and actuation components and related methods |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2223571A (en) | 1990-04-11 |
| GB8822693D0 (en) | 1989-03-30 |
| JPH03502735A (en) | 1991-06-20 |
| GB2223571B (en) | 1992-09-02 |
| WO1990003556A1 (en) | 1990-04-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| 17P | Request for examination filed |
Effective date: 19900508 |
|
| AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH DE FR GB IT LI LU NL SE |
|
| RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: GEC-MARCONI LIMITED |
|
| 17Q | First examination report despatched |
Effective date: 19920828 |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
| 18D | Application deemed to be withdrawn |
Effective date: 19931030 |