David W Schaefer

US Patent:

7477756, Jan 13, 2009

Filed:

Mar 2, 2006

Appl. No.:

11/366092

Inventors:

Timothy K. Wickstrom - Elk Grove Village IL, US
William J. Ballad - Buffalo Grove IL, US
David M. Schaefer - Downers Grove IL, US

Assignee:

Knowles Electronics, LLC - Itasca IL

International Classification:

H04R 25/00

US Classification:

381380, 381328

Abstract:

An insert earphone comprises a housing and at least one transducer that is located in the housing. The transducer is adapted to receive electrical energy and to responsively convert the electrical energy into acoustic energy for presentation to an eardrum of a user. The transducer is positioned within the housing so as to be in close proximity to the eardrum of the user when the housing is inserted into the ear canal. At least one sealing member is coupled to the housing. The at least one sealing member is adapted to provide an acoustic seal within the ear canal of the user.

US Patent:

20010012375, Aug 9, 2001

Filed:

Jan 5, 2001

Appl. No.:

09/755664

Inventors:

Thomas Miller - Arlington Heights IL, US
August Mostardo - Norridge IL, US
Elmer Carlson - Glenveiw IL, US
David Schaefer - Glen Ellyn IL, US

International Classification:

H04R025/00
H04R001/00
H04R009/06

US Classification:

381/418000, 381/312000

Abstract:

A balanced receiver providing significantly reduced vibration is disclosed. The balanced receiver comprises a closed loop operably attached between an armature and a diaphragm. The effective moving mass of the diaphragm is designed to match the effective moving mass of the armature. The closed loop facilitates the balancing of the motion of the diaphragm and the motion of the armature, thus reducing the vibration of the receiver.

US Patent:

40545369, Oct 18, 1977

Filed:

Jul 2, 1976

Appl. No.:

5/702306

Inventors:

David P. Schaefer - Hinsdale IL
Linda Pluta Gamage - Jay ME

Assignee:

Nalco Chemical Company - Oak Brook IL

International Classification:

B01J 1300

US Classification:

252313S

Abstract:

A process for preparing silica sols substantially free of alkali metal ions which comprises A. adding to a boiling aqueous solution of a lower alkanol amine a 2-10% by weight aqueous solution of silicic acid, the mole ratio of SiO. sub. 2 to lower alkanol amine being in the range of from 1:1 to 100:1; B. evaporating water during the addition of the silicic acid to the aqueous solution of the lower alkanol amine so as to maintain a constant volume; C. recovering the aqueous colloidal silica sol which is substantially free of alkali metal ions, said sol having a mole ratio of SiO. sub. 2 to alkanol amine in the range of 1:1 to 100:1; and then if desired, D. treating this sol with both a cation and anion ion exchange resin so as to further deionize the resulting alkaline metal-free silica sol, as well as to remove substantial quantities of the alkanol amine. Then if an alkaline sol is desired, adjusting the pH of the resulting acid sol of Step D to between 9 and 10 with an aqueous solution of ammonia.

US Patent:

39487997, Apr 6, 1976

Filed:

Sep 28, 1973

Appl. No.:

5/401772

Inventors:

David P. Schaefer - Hinsdale IL
Linda J. Pluta - North Riverside IL

Assignee:

Nalco Chemical Company - Oak Brook IL

International Classification:

B01J 1300

US Classification:

252309

Abstract:

Silica organosols are described which comprise hydroxy free organic solvents as the continuous phase and as the discontinuous phase which is uniformly dispersed throughout the hydroxy free organic liquid, discrete dense particles of colloidal silica having a particle size within the range of 3 - 100 mu. Also described is a method for preparing these silica sols which comprise adding hydroxy free organic solvents to commercially available aqueous silica sols and then removing the water from the mixture by distillation.