David H Chu

US Patent:

54481252, Sep 5, 1995

Filed:

Jun 27, 1994

Appl. No.:

8/266276

Inventors:

David K. Chu - Wilmington DE

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

H01L 4108

US Classification:

310313A

Abstract:

Devices are disclosed for controlling high frequency signals by the generation of surface skimming bulk waves (SSBWs). The devices include (a) a bulk crystalline substrate of MTiOXO. sub. 4 (M is K, Rb, Tl, Cs, and/or NH. sub. 4 and X is P and/or As) having mm2 crystal symmetry and a planar-cut surface, (b) an input interdigital transducer (IDT) deposited on a signal receiving area of the substrate surface, suitable for connection to a source of electric signal and for inverse piezoelectrically generating in-plane polarized surface skimming bulk waves having a velocity in the substrate of between about 4200 m/s and 7000 m/s, (c) a second IDT deposited on a signal sending area of the substrate surface suitable for piezoelectrically generating electric output signals from said surface skimming bulk waves, and (d) an electric signal responsive device which is operably connected to the second IDT and responds to the electric output signals. Also disclosed are a method of controlling frequency of electric signals which involves piezoelectrically converting the signals into SSBWs in a substrate of MTiOXO. sub. 4 and piezoelectrically detecting SSBWs from said substrate, and a method of fluid sensing which involves piezoelectrically converting input electric signals into SSBWs in a substrate of MTiOXO. sub.

US Patent:

54478456, Sep 5, 1995

Filed:

Dec 6, 1994

Appl. No.:

8/348585

Inventors:

David K. Chu - Wilmington DE
Richard C. Ebersole - Wilmington DE
Hui Hsiung - Hockessin DE

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

G01N 33543
G01N 33551

US Classification:

435 6

Abstract:

This invention relates to analyte-responsive compositions and analyte detection methods using these compositions, and, more particularly, to such compositions based on potassium titanyl phosphate (KTP) and analogs thereof and to analyte detection methods based on piezoelectric and optical properties of materials.

US Patent:

55304109, Jun 25, 1996

Filed:

Nov 21, 1994

Appl. No.:

8/343071

Inventors:

David K.-T. Chu - Wilmington DE

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

H03H 900

US Classification:

333153

Abstract:

Acoustic frequency mixing devices for controlling high frequency signals by the generation of acoustic waves are disclosed. The devices include (a) a crystalline substrate of MTiOXO. sub. 4 (wherein M is K, Rb, Tl and/or NH. sub. 4 and X is P and/or As) having a surface with at least two input areas; and (b) an input interdigital transducer deposited on each of at least two signal input areas of said substrate surface, each IDT suitable for connection to a source of electric signal and for inverse piezoelectrically generating acoustic waves (e. g. , SAWs or B-G waves) in the substrate. For controlling high frequency electrical signals, the substrate surface has a output area and the device typically includes an output electrode (e. g. , an interdigital transducer) deposited on the signal output area of said substrate surface suitable for piezoelectrically detecting acoustic waves obtained by mixing the frequencies of waves generated by at least two input interdigital transducers, and for connecting the output electrode to an electric signal responsive device.

US Patent:

53509617, Sep 27, 1994

Filed:

Jul 31, 1992

Appl. No.:

7/924691

Inventors:

David K. Chu - Wilmington DE

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

H01L 4104
H01L 41193

US Classification:

310313A

Abstract:

Devices are disclosed for controlling high frequency signals such as optic or electric signals by the generation of acoustic waves. The devices use certain bulk or surface-modified crystalline substrates which have a surface with a receiving area and an input interdigital transducer deposited on the signal receiving area of the substrate surface which is suitable for connection to a source of signal and for inverse piezoelectrically generating acoustic waves in the crystalline substrate. The crystal substrates are of a material having a piezoelectric-elastic dielectric matrix capable of the generation of acoustic waves and for bulk substrates, are of MTiOXO. sub. 4 (where M is K, Rb, Tl, and/or NH. sub. 4 and X is P and/or As) having mm2 symmetry. The receiving area of the surface-modified crystal substrates has alternating sections of crystalline material which are aligned and have a ferroelectric domain structure opposite to that of adjacent sections, and the IDT for said substrates is in contact with said alternating sections.

US Patent:

52940926, Mar 15, 1994

Filed:

Sep 28, 1992

Appl. No.:

7/951908

Inventors:

Richard B. Wade - Laguna Beach CA
David Chu - La Palma CA

Assignee:

Bridge Products - Northbrook IL

International Classification:

F16L 3728

US Classification:

2511496

Abstract:

A quick disconnect coupler includes a seal retaining member movably mounted in a coupler housing. A sealing washer biases the retaining member toward first position, and an annular seal is mounted in the retaining member. This annular seal defines both axial and radial sealing surfaces, and it is configured to transmit sufficient force to the seal retaining member to move the seal retaining member to a rearward position in response to a first, larger diameter plug bearing on the axial sealing surface, and to form a radial seal around a second, smaller diameter plug.

US Patent:

58604472, Jan 19, 1999

Filed:

May 10, 1996

Appl. No.:

8/644357

Inventors:

David Chu - Santa Ana CA

International Classification:

F16K 3112

US Classification:

13750525

Abstract:

An in line fluid pressure regulating and pressure relief device having a regulator body with an axial bore therethrough with an inlet chamber conectable to a source of fluid under pressure and an outlet chamber connect able to a device requiring fluid under substantially constant pressure. A fluid pressure regulator located in the regulator body maintains fluid pressure at the outlet chamber at a constant predetermined level. A bleed piston located in the axial bore between the inlet chamber and to the pressure regulating means loses contact with said pressure regulating piston when the pressurized fluid source is removed from the regulator or drops below a certain level relieving substantially all pressure in said exit chamber and any attached device passively rendering the device inoperable.

US Patent:

51673983, Dec 1, 1992

Filed:

Feb 8, 1991

Appl. No.:

7/652853

Inventors:

Richard B. Wade - Laguna Beach CA
David Chu - La Palma CA

Assignee:

Bridge Products, Inc. - Northbrook IL

International Classification:

F16L 3728

US Classification:

2511496

Abstract:

A quick disconnect coupler includes a seal retaining member movably in a coupler housing. A sealing washer biases the retaining member toward first position, and an annular seal is mounted in the retaining member. This annular seal defines both axial and radial sealing surfaces, and it is configured to transmit sufficient force to the seal retaining member to move the seal retaining member to a rearward position in response to a first, larger diameter plug bearing on the axial sealing surface, and to form a radial seal around a second, smaller diameter plug.

US Patent:

50222686, Jun 11, 1991

Filed:

May 22, 1989

Appl. No.:

7/355540

Inventors:

H. Alan Wolf - Franklin Lakes NJ
David L. Chu - Baton Rouge LA

Assignee:

Exxon Research and Engineering Company - Florham Park NJ

International Classification:

G01N 924

US Classification:

73602

Abstract:

Vibrational Analysis technology translates acoustic/vibratory energy created by industrial processes into useful, process-related information. This invention enables a non-acoustical expert to easily collect and interpret the data.