Patents by Inventor Chi-Ming Chan
Chi-Ming Chan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 5852397Abstract: A circuit protection device which comprises first and second laminar electrodes; a laminar PTC conductive polymer resistive element sandwiched between the electrodes; a third laminar conductive member which is secured to the same face of the PTC element as the second electrode but is separated therefrom; and an electrical connector which connects the third conductive member and the first electrode. This permits connection to both electrodes from the same side of the device, so that the device can be connected flat on a printed circuit board, with the first electrode on top, without any need for leads. The connector is preferably a cross-conductor which passes through an aperture in the PTC element, because this makes it possible to carry out the steps for preparing the devices on an assembly which corresponds to a number of individual devices, with division of the assembly as the final step.Type: GrantFiled: July 25, 1997Date of Patent: December 22, 1998Assignee: Raychem CorporationInventors: Chi-Ming Chan, Michael Zhang, Daniel Chandler, Shou-Mean Fang, Dennis Siden, Mark Thompson
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Patent number: 5451919Abstract: A conductive polymer composition which has a resistivity of less than 10 ohm-cm and which exhibits PTC behavior comprises a polymeric component and a particulate conductive filler. The polymeric component comprises a first crystalline fluorinated polymer having a first melting point T.sub.m1 and a second crystalline fluorinated polymer having a second melting point T.sub.m2 which is from (T.sub.m1 +25).degree. C. to (T.sub.m1 +100).degree. C. The composition exhibits one of a number of characteristics, including a relatively high PTC anomaly. The composition is useful in circuit protection devices to be used at high ambient conditions.Type: GrantFiled: June 29, 1993Date of Patent: September 19, 1995Assignee: Raychem CorporationInventors: Edward F. Chu, Ann Banich, Robert Ives, Steven Sunshine, Chi-Ming Chan
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Patent number: 5436609Abstract: An electrical device in which a conductive terminal is physically and electrically attached directly or indirectly to a face of a laminar PTC resistive element. The terminal comprises a laminar portion and a non-laminar shaped portion which lies within a projection of the periphery of the PTC resistive element. The shaped portion serves to improve thermal transfer between the PTC element and the atmosphere surrounding the device. Devices of the invention are useful as circuit protection devices.Type: GrantFiled: July 6, 1993Date of Patent: July 25, 1995Assignee: Raychem CorporationInventors: Chi-Ming Chan, Shou-Mean Fang
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Patent number: 5247277Abstract: An electrical device in which a first connection element is in electrical contact with a resistive element. The first connection element defines a cavity into which, when the cavity is empty, a second connection element can be inserted. The second connection element, which may be connected to a source of electrical power, is partially within the cavity, makes physical and electrical contact with the first connection element, and protrudes from the cavity. Such devices can be made in a continuous process by a method of the invention. They are particularly suitable for insertion into a circuit board.Type: GrantFiled: May 27, 1992Date of Patent: September 21, 1993Assignee: Raychem CorporationInventors: Shou-Mean Fang, Vijay K. Dhingra, Chi-Ming Chan, Daniel Chandler
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Patent number: 5122775Abstract: An electrical device in which a first connection element is in electrical contact with a resistive element. The first connection element defines a cavity into which, when the cavity is empty, a second connection element can be inserted. The second connection element, which may be connected to a source of electrical power, is partially within the cavity, makes physical and electrical contact with the first connection element, and protrudes from the cavity. Such devices can be made in a continuous process by a method of the invention. They are particularly suitable for insertion into a circuit board.Type: GrantFiled: February 14, 1990Date of Patent: June 16, 1992Assignee: Raychem CorporationInventors: Shou-Mean Fang, Vijay K. Dhingra, Chi-Ming Chan, Daniel Chandler
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Patent number: 5106540Abstract: A composition which comprises a matrix polymer and, distributed therein, a particulate conductive filler. At least some of the filler particles are composed of a conductive polymer composition and/or the matrix comprises a sintered polymer. The matrix polymer and the filler particles and the method of distributing the particles are such that the particles maintain their identity in the matrix. For example, the particles are preferably highly cross-linked so that they have a hot modulus of at least 250 psi if the composition is prepared by melt extrusion or another process involving a high degree of shear; or a low-shear process such as sintering can be used. Preferably the matrix polymer is capable of coating the filler particles; for example, the matrix polymer and the filler polymer may be chemically similar. The invention is particularly useful for preparing compositions which have high resistivities, eg. 1000 ohm.cm or more, and which can be prepared with a high degree of reproduceability.Type: GrantFiled: July 21, 1987Date of Patent: April 21, 1992Assignee: Raychem CorporationInventors: Pradeep Barma, Chi-Ming Chan, Manoochehr Mohebban, Nachum Rosenzweig
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Patent number: 5106538Abstract: A composition which comprises a matrix polymer and, distributed therein, a particulate conductive filler. At least some of the filler particles are composed of a conductive polymer composition and/or the matrix comprises a sintered polymer. The matrix polymer and the filler particles and the method of distributing the particles are such that the particles maintain their identity in the matrix. For example, the particles are preferably highly cross-linked so that they have a hot modulus of at least 250 psi if the composition is prepared by melt extrusion or another process involving a high degree of shear; or a low-shear process such as sintering can be used. Preferably the matrix polymer is capable of coating the filler particles; for example, the matrix polymer and the filler polymer may be chemically similar. The invention is particularly useful for preparing compositions which have high resistivities, e.g. 1000 ohm.cm or more, and which can be prepared with a high degree of reproduceability.Type: GrantFiled: January 11, 1990Date of Patent: April 21, 1992Assignee: Raychem CorporationInventors: Pradeep Barma, Chi-Ming Chan, Manoochehr Mohebban, Nachum Rosenzweig, Eugen L. Kurjatko
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Patent number: 5089801Abstract: An electrical device in which a conductive terminal is physically and electrically attached to a laminar resistive element by means of a laminar conductive element. The three layers are positioned in such a way that the periphery of the conductive element does not extend beyond the first periphery and at least a part of the periphery of the conductive terminal lies within the first periphery. In a preferred embodiment the conductive element is solder and the periphery of the conductive terminal is shaped in such a way that no excess solder bridges from one laminar surface of the resistive element to the other. Devices of the invention are useful as circuit protection devices.Type: GrantFiled: September 28, 1990Date of Patent: February 18, 1992Assignee: Raychem CorporationInventors: Chi-Ming Chan, Shou-Mean Fang
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Patent number: 4866452Abstract: A dish antenna for receiving or transmitting signals, e.g. via a satellite, is heated by means of radiant heat from an electrical heater located behind the antenna and spaced apart therefrom. This keeps the antenna free from ice and snow and minimizes distortion. The heater is preferably a self-regulating sheet heater comprising a PTC conductive polymer.Type: GrantFiled: January 24, 1989Date of Patent: September 12, 1989Assignee: Raychem CorporationInventors: Pradeep Barma, Chi-Ming Chan
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Patent number: 4801785Abstract: Improvements to electrical devices comprising conductive polymer compositions are described. The device, preferably a heater, comprises two electrodes, preferably planar electrodes and a conductive polymer composition, which preferably exhibits PTC behavior, and which is preferably sandwiched between the electrodes. At least one of the electrodes comprises a metal with a thin layer of high resistivity material attached thereto, e.g. anodized aluminum, so that the layer separates the electrode and the conductive polymer composition. This raises the room temperature resistance of the device and thus reduces the in-rush current.Type: GrantFiled: January 14, 1986Date of Patent: January 31, 1989Assignee: Raychem CorporationInventors: Chi-Ming Chan, Pradeep Barma, David Chazan, David Liu