WO1997016834A1 - Lame de capteur a piezoluminescence comprenant une couche piezoresistive - Google Patents

Lame de capteur a piezoluminescence comprenant une couche piezoresistive Download PDF

Info

Publication number
WO1997016834A1
WO1997016834A1 PCT/US1996/017205 US9617205W WO9716834A1 WO 1997016834 A1 WO1997016834 A1 WO 1997016834A1 US 9617205 W US9617205 W US 9617205W WO 9716834 A1 WO9716834 A1 WO 9716834A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
pressure
transducer
piezoresistive
ofthe
Prior art date
Application number
PCT/US1996/017205
Other languages
English (en)
Inventor
Edward S. Gaffney
Original Assignee
Gre, Incorporated
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Gre, Incorporated filed Critical Gre, Incorporated
Priority to AU74780/96A priority Critical patent/AU7478096A/en
Publication of WO1997016834A1 publication Critical patent/WO1997016834A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/247—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet using distributed sensing elements, e.g. microcapsules

Definitions

  • the present invention relates to sensors for measuring pressure and/or stress and more particularly, to an improved sensor that converts a pressure or stress pattern into an optical image.
  • stress usually refers to a tensor quantity which may vary depending on the orientation ofthe surface of measurement and depending on the direction ofthe measurement along that surface.
  • pressure refers to a stress that is independent of orientation. For the purposes of this discussion, the terms “stress” and “pressure” are used interchangeably.
  • Prior art stress sensing devices typically convert mechanical energy into electrical energy. The electrical energy is then converted into a signal which can be processed and transmitted to electronic recording devices.
  • One method for constructing such a stress sensor utilizes piezoresistive materials. These materials respond to the application of stress with a change in their electrical resistivity.
  • the most common types are homogeneous media, such as metals and semiconductors, and composite media. In the homogeneous media, the electronic structure ofthe material is altered in response to the internal strains in the medium. This change in electronic structure may result in either an increase or a decrease in resistivity in response to a compressive stress.
  • Typical examples of homogeneous piezoresistive media include metals such as ytterbium (Yb) and manganin (Cu ⁇ Mn ⁇ Ni ⁇ ) and semiconductors such as silicon.
  • Composite piezoresistive media are composed of particles of a metallic or semiconducting material suspended in a (relatively) compliant insulator, as shown in Figure 1. In this case, the change in electrical resistivity ofthe bulk composite is the result ofthe decreasing separation and increasing contact between the conducting particles. As a result, such media always become more conductive upon compression.
  • Typical examples of composite piezoresistive media include "carbon gauges” (such as those from Dynasen Co ⁇ oration, Goleta, CA) and resistive inks and adhesives (such as those from Metech, Incorporated, of Elverson, PA, or Creative Materials Inco ⁇ orated of Tyngsboro, MA).
  • carbon gauges such as those from Dynasen Co ⁇ oration, Goleta, CA
  • resistive inks and adhesives such as those from Metech, Incorporated, of Elverson, PA, or Creative Materials Inco ⁇ orated of Tyngsboro, MA.
  • a sensor system to measure the distribution of pressure on a surface can be constructed by placing several such sensors at various locations on the surface. If only a rough measure ofthe variation of pressure on the surface is desired, this is a feasible approach. However, if a precise measurement ofthe distribution is required, this brute force approach becomes cumbersome because of the large number of individual sensors and electrical connections, and hence, there is an upper limit on size ofthe sensor array. In addition, the spatial resolution of such an array is limited by the dimension ofthe individual piezoresistive sensors.
  • the individual piezoresistive sensors are screen-printed over one or both sets of electrical leads so that an individual sensor is formed at each intersection when the two substrates are brought together.
  • the system taught in U.S. Patent 4,856,993 uses a contact resistance composite piezoresistive ofthe type described by Eventoff in U. S. Patent No. 4,315,238. The other two employ a volume resistivity approach. Maness also describes multiplexing, control circuits, a regulator, an interface circuit and a computer to control the sensor. These are all made necessary by the large number of distinct electrical signals which must be kept separate so that the data can be properly inte ⁇ reted. Pressure distribution sensors ofthe type described by Maness are adequate to provide pressure distributions with a spatial resolution on the order of 1 millimeter. However, the number of data points becomes very large as the total area to be surveyed increases. Typically, arrays that are larger than about 50 by 50 are not practical. Furthermore, large areas cannot be observed with high spatial resolution because the number of leads to be interrogated becomes extreme.
  • Yet another problem with this type of sensor array is the need to provide a computer or similar device for processing the data into a usable form.
  • the computer typically converts the individual pressure measurements into some form of graphical display or image so that an observer can better absorb the large volume of data inherent in such a pressure distribution measurement.
  • This processing circuitry adds to the cost ofthe system and makes direct real time observations difficult, particularly at locations that do not easily support an online computer.
  • the present invention comprises a pressure transducer that converts a pressure distribution directly into a visible image.
  • the transducer may be viewed as comprising a two layered structure sandwiched between first and second electrodes that provide a bias potential.
  • the intermediate layers comprise a piezoresistive layer and a light emitting layer.
  • the piezoresistive layer includes a material whose resistivity varies as a function of pressure.
  • the light emitting layer is constructed from a material whose light output varies in relation to the current passing through the layer.
  • Figure 1 is a cross-sectional view of a pressure sensing transducer according to the present invention.
  • Figure 2 is a cross-sectional view of a second embodiment of a pressure sensing transducer according to the present invention.
  • Figure 3 is a cross-sectional view of a third embodiment of a pressure sensing transducer according to the present invention.
  • Figure 4 is a cross-sectional view of a composite piezoresistive layer according to the present invention. Detailed Description of the Invention
  • FIG. 1 is a cross-sectional view of a pressure sensing sheet 10 according to the present invention.
  • Sheet 10 may be viewed as comprising a piezoresistive layer 12 which converts variations in pressure to variations in resistivity which are then used to vary light output of a luminescent sheet 14.
  • the luminescent sheet can be constructed from any light emitting material whose light output depends on the current passing therethrough. The current is provided by maintaining a potential difference between a first continuous electrode 15 on one surface ofthe piezoresistive layer and a second continuous electrode 16 on the surface of luminescent sheet 14 that is not in contact with piezoresistive layer 12.
  • the present invention has superior spatial resolution compared to prior art sensor arrays.
  • the spatial resolution ofthe present invention derives in part from the fact that piezoresistive layer 12 has a much lower electrical resistance through its thickness than it does between widely separated points in the plane ofthe sheet.
  • the piezoresistive layer is very thin, typically 0.0004 - 0.004 inches (10 - 100 ⁇ m) thick. Thus current will flow more easily across this short distance than it will flow along the plane ofthe material to some point which might have a lower poten ⁇ tial.
  • the preferred embodiment ofthe present invention utilizes composite piezoresistive materials which, as discussed above, are anisotropic.
  • the piezoresistive layer consists of two resistive layers which are touching but not in intimate contact. As the pressure increases, the extent ofthe contact between the two layers increases, and hence, the resistance at the point of increased pressures decreases. Since the individual layers have high resistance to current flow parallel to the surface of each layer, the current modulation is primarily at the point of increased pressure.
  • electrode 16 must be of sufficient optical transparency to permit photons from light emitting layer 12 to escape. If, on the other hand, the output ofthe piezoluminescent sensor is to be viewed from the side with the piezoresistive member, then both electrode 14 and piezoresistive layer 12 must be transparent. Since transparent thin film electrodes are known to the art, and since the resolution would be decreased by requiring the image to be viewed through piezoresistive layer 12, the preferred embodiment ofthe present invention is constructed such that the image is viewed in the first configuration discussed above.
  • a material such as indium-tin oxide may be used to construct the transparent electrode.
  • Indium- tin oxide may also be used if only moderate flexure is to be encountered.
  • a flexible transparent conductor such as polyaniline is preferred.
  • LEDs light emitting diodes
  • electrolumi ⁇ nescent lamps although other materials currently being developed such as surface emitting diode lasers and quantum cascade lasers (J. Faist et al., Science 1994) may be also be used if cost-effective sheets become available.
  • a light emitting diode generates light when an electrical current is carried in a semi ⁇ conductor diode either by electrons or by holes.
  • a semiconductor diode may be constructed as a layered device consisting of two or more layers, at least one of which is a hole conductor. When the semiconductor diode is subjected to an appropriate bias potential, it will begin to emit light. The light output increases until it reaches a saturation current.
  • Semiconductor diodes based on polymer thin film materials such as poly(vinylene phenylene) are known to the art and may be used to provide LED's that emit light at various wavelengths. These polymer LEDs may consist of a single layer of semiconducting material or of several layers which transport only electrons, transport only holes, or are electro ⁇ luminescent (Tang and VanSlyke. J. Appl. Phvs.. 1987; Adachi et al, Japan J. Appl. Phvs.. 1988a,b; Friend et al, Phys. World. 1992).
  • the polymer diodes are often produced by methods which are consistent with production of large area devices. It is also fairly easy to change the material with ligands or dopants, which allows for variations of photon energy and threshold voltage.
  • Electroluminescent lamps consist of a phosphor layer separated from two electrodes by thin layers of dielectric material. The electrode and dielectric on at least one side must be transparent. When a high voltage alternating current (AC) is applied to the electrodes, elec- trons are ejected from the negative electrode and accelerated toward the positive electrode. Some of these electrons collide with the phosphor material which is thereby stimulated to emit radiation in the form of visible light. The intensity ofthe light depends on the amount of current flowing through the EL lamp.EL lamps are available commercially. For example, Leading Edge Industries, Inc., of Minnetonka, Minnesota sells lamps which are constructed by thick-film processes on polymer substrates.
  • the piezoresistive layer may be constructed utilizing pressure sensitive resistive inks which are available in a wide range of volume resistivity value including the range about 10 " 3 ⁇ m to 10 6 ⁇ m.
  • the sensor must be designed with the proper combination of thickness and resistivity ofthe piezoresistive layer to match the electronic properties ofthe LED layer. If the resistance is too large there will not be enough current flowing to produce perceptible luminescence. If the resistance is too low, the change in current produced by a fractional decrease in resistance will not be great enough to cause a perceptible change in luminescence. Values of resistance between these two extremes provide the useful operating range.
  • the bias voltage is of an alternating current (AC) nature and of such an amplitude that luminescence is just stimulated in the LED member at the peak ofthe voltage but no luminescence occurs at lower voltages.
  • AC alternating current
  • the LED member will flash weakly and briefly at the frequency ofthe AC bias.
  • Application of a stress on the piezoresistive layer lowers the resistance through the layer, resulting in a larger voltage drop across the LED layer.
  • the intensity and the duration ofthe luminescence at the peak of each bias voltage cycle is increased. If the frequency ofthe bias voltage is high enough (about 30 Hz for human visual perception), the change will be perceived as an increase in the observed level of steady luminescence.
  • the piezoresistance member may be a material such as manganin whose resistivity increases with pressure and the level ofthe AC bias set so that luminescence in the LED member is saturated for most of the AC bias cycle. In this case, the light level would decrease in re ⁇ sponse to a stimulus.
  • a sensor according to the present invention may be constructed based on an EL lamp layer as follows.
  • the transparent electrode is deposited on a transparent substrate by sputtering, pulsed laser deposition, thermal evaporation or other suitable process.
  • a dielectric layer with embedded phosphorescent particles is then printed on the transparent electrode by screen printing to form the light emitting layer.
  • the piezoresistive layer can then be printed over the light emitting layer and covered with a continuous conducting layer.
  • an electron emitter comprising a layer of anisotropic conductor may be deposited on the light emitting layer before the application ofthe piezoresistive layer.
  • This anisotropic conductor is preferably a continuous sheet of material which is intrinsically anisotropic in its electrical conductivity, such as copper phthalocyanine or an anisotropically conducting adhesive such as 3M 9703 from 3M Co ⁇ ., St. Paul, Minnesota
  • the opaque electrode is used as the base for building the device.
  • a thin, flexible conducting sheet such as aluminum foil or an aluminized polymer film may be used.
  • the piezoresistive member is then deposited, preferably by screen or flexographic printing. A pattern of isolated spots may be produced by the deposition process to further enhance the spatial resolution.
  • the LED layer is deposited over the piezoresistive member using methods such as those described in the Gustafsson et al reference discussed above. A vapor barrier may then be applied over the LED layer if required.
  • FIG. 2 illustrates a sensor 20 according to the present invention that provides a pressure measurement that is indicated by the portion ofthe sensor that emits lights. In this case different portions ofthe sensor will be activated when the pressure exceeds a certain value.
  • This device consists of con ⁇ tinuous top and bottom electrodes 21 and 29.
  • An electroluminescent layer 23 is connected by a resistive sheet 22 to top electrode 21.
  • Resistive sheet 22 is composed of separate bands of different piezoresistivities 24-28.
  • band 24 requires a high pressure in order to deliver current to the portion ofthe electroluminescent layer 23 adjacent to it, whereas band 28 requires only a low pressure to deliver current to the portion of layer 23 adjacent to it.
  • Bands 25-27 have intermediate and sequential sensitivities. By noting the loca ⁇ tion ofthe edge ofthe light an operator or an automatic control system can determine the pressure.
  • a device such as that illustrated in Figure 2 can be constructed by using piezoresistive materials with the desired sensitivities.
  • the senor can be used to provide a display if the pressure is greater than a predetermined value or within a predetermined range.
  • a sensor is shown in Figure 3 at 30.
  • sensor 30 only region 33 ofthe area between the electroluminescent lamp layer 31 and the first electrode 32 is printed with piezoresistive ink. The remaining area, region 34, is printed with an insulating ink.
  • region 34 is printed with an insulating ink.
  • region 34 outside of region 33 is printed with a piezoresistive ink having a threshold pressure that is greater than that ofthe ink used in region 33, then the message will disappear into a uniformly illuminated field when the pressure exceeds the saturation pressure ofthe ink in region 34. In this manner, a sensor that displays a message when the pressure is between predetermined limits may be constructed.
  • An embodiment ofthe present invention which operates as a threshold sensor rather than a continuously variable sensor can be constructed by replacing the piezoresistive layer with a composite layer as shown in Figure 4 at 50.
  • Composite layer 50 comprises two layers 51 and 52 separated by an insulating mesh 53. At least one ofthe two layers must be sufficiently flexible to deform and touch the other layer when a pressure above the threshold pressure is applied.
  • both ofthe layers are resistive layers to reduce arcing.
  • one or both ofthe layers may be conductors. In this case, the layer in contact with the light emitting layer may be eliminated so that pressure causes the deformable layer 51 to contact the light emitting layer directly.
  • the insulating mesh may be constructed from a nylon mesh, non-conducting paints, or a powder of non-conducting particles.
  • layer 51 is composed of a resistive material
  • the structure shown in Figure 4 is itself a piezoresitive layer at pressures above some threshold pressure which depends on the deformation properties of layer 51 and the spacers 53.
  • the pressure on layer 51 increases, the area ofthe contact area between layer 51 and layer 52 increases. Since the resistance depends on the area of contact when a resistive material is used, the resulting structure is a piezoresitive layer as discussed above.
  • a piezoresitive structure can also be constructed by omitting the spacers 53 and utilizing a rough surface on either layer 51 or layer 52 to provide the spacing function.
  • at least one ofthe layers is resistive, and at least one ofthe layers is deformable under pressure such that the area of contact between the two layers varies with the pressure.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Pressure Sensors (AREA)

Abstract

L'invention porte sur un transducteur de pression (10) convertissant directement une répartition de pression en une image visible. Ce transducteur (10) peut être considéré comme comprenant une structure à deux couches prise en sandwich entre une première et une seconde électrode fournissant un potentiel de polarisation. Les couches intermédiaires comprennent une couche piézorésistive (12) et une couche émettant de la lumière (14). La couche piézorésistive (12) comporte un matériau ou une structure dont la résistance spécifique varie en fonction de la pression. La couche émettrice de lumière (14) est faite d'un matériau ou d'une structure dont l'émission lumineuse varie selon le courant traversant la couche.
PCT/US1996/017205 1995-11-01 1996-10-24 Lame de capteur a piezoluminescence comprenant une couche piezoresistive WO1997016834A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU74780/96A AU7478096A (en) 1995-11-01 1996-10-24 Piezoluminescent sensor sheet with a piezoresistive layer

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US55158195A 1995-11-01 1995-11-01
US08/551,581 1995-11-01

Publications (1)

Publication Number Publication Date
WO1997016834A1 true WO1997016834A1 (fr) 1997-05-09

Family

ID=24201844

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/017205 WO1997016834A1 (fr) 1995-11-01 1996-10-24 Lame de capteur a piezoluminescence comprenant une couche piezoresistive

Country Status (2)

Country Link
AU (1) AU7478096A (fr)
WO (1) WO1997016834A1 (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999012472A1 (fr) * 1997-09-05 1999-03-18 Who? Vision Systems Inc. Representation d'images d'objets en relief
WO1999027485A2 (fr) * 1997-11-25 1999-06-03 Who? Vision Systems Inc Technique et systeme permettant un acces informatique et une commande de curseur au moyen d'un generateur d'images objets en relief
EP0957445A2 (fr) * 1998-05-15 1999-11-17 Mirae Corporation Dispostifif à contact émetteur de lumière, un procédé pour sa fabrication et dispositif d'entrée à contact l'utilisant
US6420724B1 (en) * 1999-06-22 2002-07-16 Agfa-Gevaert Method of image formation, dosimetry and personal monitoring
US6476406B1 (en) * 1999-06-22 2002-11-05 Agfa-Gevaert Devices equipped with tribostimulable storage phosphors
US6910376B2 (en) 2001-02-22 2005-06-28 Metso Paper, Inc. Measurement method and system in the manufacture of paper or paperboard
WO2007107522A1 (fr) * 2006-03-17 2007-09-27 Iee International Electronics & Engineering S.A. Dispositifs avec une couche sensible à la pression comprenant un matériau organique intrinsèquement sensible à la pression
WO2016172917A1 (fr) * 2015-04-30 2016-11-03 深圳纽迪瑞科技开发有限公司 Capteur de pression lumineuse et bouton de commande par effleurement correspondant ainsi que dispositif électronique
CN109443630A (zh) * 2018-10-31 2019-03-08 福州大学 一种基于qled发光器件的压力传感器
CN111982671A (zh) * 2020-06-30 2020-11-24 天地科技股份有限公司 压力拱可视化的碎石锚固试验装置及方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2816236A (en) * 1956-06-19 1957-12-10 Gen Electric Method of and means for detecting stress patterns
US3065378A (en) * 1959-10-19 1962-11-20 American Soc For Technion Isra Visual display and readout systems
US3154720A (en) * 1960-04-29 1964-10-27 Rca Corp Solid state display device
US4878107A (en) * 1985-10-29 1989-10-31 Hopper William R Touch sensitive indicating light

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2816236A (en) * 1956-06-19 1957-12-10 Gen Electric Method of and means for detecting stress patterns
US3065378A (en) * 1959-10-19 1962-11-20 American Soc For Technion Isra Visual display and readout systems
US3154720A (en) * 1960-04-29 1964-10-27 Rca Corp Solid state display device
US4878107A (en) * 1985-10-29 1989-10-31 Hopper William R Touch sensitive indicating light

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6856383B1 (en) 1997-09-05 2005-02-15 Security First Corp. Relief object image generator
WO1999012472A1 (fr) * 1997-09-05 1999-03-18 Who? Vision Systems Inc. Representation d'images d'objets en relief
US6501846B1 (en) 1997-11-25 2002-12-31 Ethentica, Inc. Method and system for computer access and cursor control using a relief object image generator
WO1999027485A2 (fr) * 1997-11-25 1999-06-03 Who? Vision Systems Inc Technique et systeme permettant un acces informatique et une commande de curseur au moyen d'un generateur d'images objets en relief
WO1999027485A3 (fr) * 1997-11-25 1999-11-18 Xl Vision Inc Technique et systeme permettant un acces informatique et une commande de curseur au moyen d'un generateur d'images objets en relief
EP0957445A3 (fr) * 1998-05-15 2000-02-23 Mirae Corporation Dispostifif à contact émetteur de lumière, un procédé pour sa fabrication et dispositif d'entrée à contact l'utilisant
EP0957445A2 (fr) * 1998-05-15 1999-11-17 Mirae Corporation Dispostifif à contact émetteur de lumière, un procédé pour sa fabrication et dispositif d'entrée à contact l'utilisant
US6476406B1 (en) * 1999-06-22 2002-11-05 Agfa-Gevaert Devices equipped with tribostimulable storage phosphors
US6420724B1 (en) * 1999-06-22 2002-07-16 Agfa-Gevaert Method of image formation, dosimetry and personal monitoring
US6910376B2 (en) 2001-02-22 2005-06-28 Metso Paper, Inc. Measurement method and system in the manufacture of paper or paperboard
WO2007107522A1 (fr) * 2006-03-17 2007-09-27 Iee International Electronics & Engineering S.A. Dispositifs avec une couche sensible à la pression comprenant un matériau organique intrinsèquement sensible à la pression
WO2007107523A1 (fr) * 2006-03-17 2007-09-27 Iee International Electronics & Engineering S.A. Capteur de pression pour mesurer une caractéristique d'une pression appliquée sur le capteur
WO2016172917A1 (fr) * 2015-04-30 2016-11-03 深圳纽迪瑞科技开发有限公司 Capteur de pression lumineuse et bouton de commande par effleurement correspondant ainsi que dispositif électronique
CN106662490A (zh) * 2015-04-30 2017-05-10 深圳纽迪瑞科技开发有限公司 可发光的压力传感器及其触控按键和电子设备
CN106662490B (zh) * 2015-04-30 2019-10-15 深圳纽迪瑞科技开发有限公司 可发光的压力传感器及其触控按键和电子设备
US10564764B2 (en) 2015-04-30 2020-02-18 Shenzhen New Degree Technology Co., Ltd. Luminous pressure sensor and touch control button thereof, and electronic device
CN109443630A (zh) * 2018-10-31 2019-03-08 福州大学 一种基于qled发光器件的压力传感器
CN111982671A (zh) * 2020-06-30 2020-11-24 天地科技股份有限公司 压力拱可视化的碎石锚固试验装置及方法
CN111982671B (zh) * 2020-06-30 2023-08-08 天地科技股份有限公司 压力拱可视化的碎石锚固试验装置及方法

Also Published As

Publication number Publication date
AU7478096A (en) 1997-05-22

Similar Documents

Publication Publication Date Title
US6530527B1 (en) Value or security product with luminescent security elements and method for the production and use thereof in respect to visual and machine-operated detection of authenticity
US5446334A (en) Piezoluminescent, pyroluminescent sensor
US9229597B2 (en) Integrated capacitive touch screen and LED layer
CA1272393A (fr) Senseur tactile electrographique determinant la coordonnee z
CN104868778B (zh) 一种自驱动瞬态应力传感装置
WO1997016834A1 (fr) Lame de capteur a piezoluminescence comprenant une couche piezoresistive
CN100381989C (zh) 位置检测设备及包括其的数据输入设备
US3634714A (en) Electroluminescent display device with apertured electrodes
US11698316B2 (en) Pressure sensor, manufacturing method thereof, pressure sensing method and display device
US2922076A (en) Display device
US3740616A (en) Electrically luminescent device
GB2178242A (en) See-through coordinate graphic input tablet
CN102365770A (zh) 电致发光装置和分段照明装置
US6768126B2 (en) Thermal image identification system
EP0274529A4 (fr) Affichage a cristaux liquides.
US8274076B2 (en) Diode employing with carbon nanotube
US3038097A (en) Indicating means
US3502885A (en) Non-coplanar electrode photoconductor structure and electroluminescent-photoconductor array
CN207266366U (zh) 柔性印刷电路板与线光源
US3531676A (en) Electroluminescent cell for large area illumination
US3571654A (en) Electroluminescent display system including a preselectably applied low resistance material means
JP2003302204A (ja) 歪分布表示装置
KR960007993B1 (ko) 위치감지소자 일체형 전계발광표시소자
US20100084635A1 (en) Recording level gauge type organic light emitting diode
CN217655882U (zh) 一种发光面板以及光疗装置

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU CA JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 97517436

Format of ref document f/p: F

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: CA