Patents by Inventor Thomas P. Hedblom

Thomas P. Hedblom 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).

  • Publication number: 20030035927
    Abstract: Composite pavement markings with improved wear resistance and other advantages are disclosed. The composite pavement markings typically include a unitary retroreflective article attached to a base pavement marking. With the composite construction, different portions of the pavement marking are provided at different heights. The taller portions of the pavement marking may preferably offer some protection to the shorter portions from wear caused by vehicle traffic and/or snowplow blades. By combining two different retroreflective pavement markings to form the composite pavement markings of the present invention, a combination of features and properties may be obtained that is provided by neither of the pavement markings alone. Methods of manufacturing composite pavement markings are also disclosed.
    Type: Application
    Filed: August 14, 2001
    Publication date: February 20, 2003
    Applicant: 3M Innovative Properties Company
    Inventors: Eric E. Rice, Thomas P. Hedblom
  • Patent number: 6479132
    Abstract: The articles of the present invention comprise pavement marking articles which are retroreflective under dry and/or wet conditions. The articles comprise a monolayer of exposed-lens optical elements, a spacing layer, and a reflective layer. The present invention also provides a method of making said pavement marking articles.
    Type: Grant
    Filed: December 27, 2001
    Date of Patent: November 12, 2002
    Assignee: 3M Innovative Properties Company
    Inventors: Thomas P. Hedblom, Eric E. Rice, Terry L. Bescup, Joseph M. McGrath
  • Publication number: 20020146538
    Abstract: The articles of the present invention comprise pavement marking articles which are retroreflective under dry and/or wet conditions. The articles comprise a monolayer of exposed-lens optical elements, a spacing layer, and a reflective layer. The present invention also provides a method of making said pavement marking articles.
    Type: Application
    Filed: December 27, 2001
    Publication date: October 10, 2002
    Inventors: Thomas P. Hedblom, Eric E. Rice, Terry L. Bescup, Joseph M. McGrath
  • Patent number: 6431788
    Abstract: A pavement marking and methods of making pavement markings are disclosed in which the pavement markings exhibit enhanced wear resistance to, e.g., snowplow blades. The pavement markings include elongated protuberances in which successive elongated protuberances overlap along at least the longitudinal direction and may also overlap in a direction transverse to the longitudinal axis. Other protuberances are interspersed between the elongated protuberances to improve retroreflectivity. The elongated protuberances are provided to support, e.g., a snowplow blade moving over the pavement marking.
    Type: Grant
    Filed: November 13, 1998
    Date of Patent: August 13, 2002
    Assignee: 3M Innovative Properties Company
    Inventors: Thomas P. Hedblom, Eric E. Rice, Curtis W. Meverden, Gregory E. Gilligan, Thomas D. Krech
  • Patent number: 6365262
    Abstract: The articles of the present invention comprise pavement marking articles which are retroreflective under dry and/or wet conditions. The articles comprise a monolayer of exposed-lens optical elements, a spacing layer, and a reflective layer. The present invention also provides a method of making said pavement marking articles.
    Type: Grant
    Filed: October 20, 1998
    Date of Patent: April 2, 2002
    Assignee: 3M Innovative Properties Company
    Inventors: Thomas P. Hedblom, Eric E. Rice, Terry L. Bescup, Joseph M. McGrath
  • Patent number: 6247818
    Abstract: The present invention comprises a method for making retroreflective elements which are retroreflective under dry and/or wet conditions. The method provides a means for placing optical elements and/or skid-resistant particles on selected surfaces.
    Type: Grant
    Filed: October 20, 1998
    Date of Patent: June 19, 2001
    Assignee: 3M Innovative Properties Company
    Inventors: Thomas P. Hedblom, Eric E. Rice
  • Patent number: 5928761
    Abstract: The articles of the present invention comprise optical elements embedded in either a core having a binder layer which is embedded in a road-binder or optical elements which are directly embedded into a binder layer. The binder layer may be part of a preformed pavement marking tape or may be applied directly to a traffic-bearing surface. The binder layer is comprised of a black pigment. The pavement marking articles of the present invention comprise one or more first region(s) wherein the first region(s) has a daytime appearance of black and is retroreflective.In another embodiment of the present invention, the pavement marking articles further comprise one or more second region(s) having a color which contrasts with black during the daytime and which is typically also retroreflective. The second region(s) is adjacent to the first region(s).
    Type: Grant
    Filed: July 16, 1997
    Date of Patent: July 27, 1999
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: Thomas P. Hedblom, Gregory F. Jacobs
  • Patent number: 5777791
    Abstract: Retroreflective articles, for example in the form of pavement markers or retroreflective elements, exhibit both wet and dry retroreflectivity by using a plurality of Type A microspheres and a plurality of Type B microspheres partially embedded in a binder layer containing specular pigments. The Type A and Type B microspheres have different average indices of refraction.
    Type: Grant
    Filed: November 26, 1996
    Date of Patent: July 7, 1998
    Assignee: Minnesota Mining and Manufacturing Company
    Inventor: Thomas P. Hedblom
  • Patent number: 5774265
    Abstract: All-ceramic retroreflective elements which may be used in pavement markings comprising an opacified ceramic core and ceramic optical elements partially embedded into the core.
    Type: Grant
    Filed: February 5, 1996
    Date of Patent: June 30, 1998
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: James P. Mathers, Chris J. Goodbrake, Kathleen A. Hachey, Thomas P. Hedblom, Kathleen M. Humpal, Roger W. Lange, David C. May, Kyung H. Moh, Thomas E. Forester
  • Patent number: 5763000
    Abstract: A pavement marking and a method of making a pavement marking, where retroreflectivity and skid-resistance can be independently controlled while making efficient use of the optical elements and skid-resistant particles. One illustrative embodiment includes two topcoats on a base sheet having first and second major surfaces, the first major surface having a plurality of protuberances located thereon which are separated by valleys. A first topcoat is attached to the first major surface of the base sheet and a second topcoat is selectively located on the protuberances. A first mixture of optical elements and/or skid-resistant particles is attached to, e.g., partially embedded in, the first topcoat and a second mixture of optical elements and/or skid-resistant particles is attached to, e.g., partially embedded in, the second topcoat.
    Type: Grant
    Filed: May 7, 1997
    Date of Patent: June 9, 1998
    Assignee: Minnesota Mining and Manufacturing Company
    Inventor: Thomas P. Hedblom
  • Patent number: 5683746
    Abstract: An improved pavement marking sheet material, and a method for making such pavement marking sheet material. The pavement marking sheet material comprises a selected configuration of upright retroreflectors. The upright retroreflectors are arranged in a selected configuration so as to maximize reflectivity as measured at actual observation geometries by allowing light to be incident to effective portions of the retroreflective elements on the upright retroreflectors.
    Type: Grant
    Filed: February 16, 1996
    Date of Patent: November 4, 1997
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: Thomas P. Hedblom, T. Ian Bradshaw
  • Patent number: 5676488
    Abstract: A pavement marking and a method of making a pavement marking, where retroreflectivity and skid-resistance can be independently controlled while making efficient use of the optical elements and skid-resistant particles. One illustrative embodiment includes two topcoats on a base sheet having first and second major surfaces, the first major surface having a plurality of protuberances located thereon which are separated by valleys. A first topcoat is attached to the first major surface of the base sheet and a second topcoat is selectively located on the protuberances. A first mixture of optical elements and/or skid-resistant particles is attached to, e.g., partially embedded in, the first topcoat and a second mixture of optical elements and/or skid-resistant particles is attached to, e.g., partially embedded in, the second topcoat.
    Type: Grant
    Filed: June 29, 1995
    Date of Patent: October 14, 1997
    Assignee: Minnesota Mining and Manufacturing Company
    Inventor: Thomas P. Hedblom
  • Patent number: 5670227
    Abstract: An improved pavement marking sheet material, and a method for making such pavement marking sheet material. The pavement marking sheet material comprises a selected configuration of upright retroreflectors. The upright retroreflectors are arranged in a selected configuration so as to maximize reflectivity as measured at actual observation geometries by allowing light to be incident to effective portions of the retroreflective elements on the upright retroreflectors.
    Type: Grant
    Filed: April 18, 1996
    Date of Patent: September 23, 1997
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: Thomas P. Hedblom, T. Ian Bradshaw
  • Patent number: 5593246
    Abstract: A pavement marking 10 includes a base sheet 12, a barrier layer 30, a layer 32 of bonding material, a multitude of optical elements 34, and skid-resistant particles 36. The base sheet 12 contains rubber and fillers and has a number of protuberances 14 projecting from its front side 28. Valleys 16 are disposed between the protuberances 14. The barrier layer 30 is disposed on the front side 28 at least in valleys 16 and preferably over protuberances 14. The layer 32 of bonding material is disposed predominantly on protuberances 14 and in this position secures the optical elements 34 and skid-resistant particles 36 to the protuberances 14 but not to the valleys 16. The coverage of the front side 28 of base sheet 12 with barrier layer 30 and bonding material 32 prevents the fillers in the base sheet 12 from becoming present on the top surface of the pavement marking 10 and thereby preserves the intended color of the marking 10.
    Type: Grant
    Filed: August 26, 1994
    Date of Patent: January 14, 1997
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: Thomas P. Hedblom, Kathleen A. Hachey, Robert L. Keech
  • Patent number: 5571362
    Abstract: A retroreflective article and a method for making same are taught. The retroreflective article comprises transparent microspheres and both specular and diffuse reflective pigments dispersed in a binder layer. The utilization of both types of pigments results in improved retroreflectivity over a greater range of entrance angles than if only one or the other pigment alone were used.
    Type: Grant
    Filed: April 7, 1995
    Date of Patent: November 5, 1996
    Assignee: Minnesota Mining And Manufacturing Company
    Inventors: Kathleen A. Hachey, Thomas P. Hedblom, David C. May
  • Patent number: 5417515
    Abstract: A retroreflective article and a method for making same are taught. The retroreflective article comprises transparent microspheres and both specular and diffuse reflective pigments dispersed in a binder layer. The utilization of both types of pigments results in improved retroreflectivity over a greater range of entrance angles than if only one or the other pigment alone were used.
    Type: Grant
    Filed: May 20, 1994
    Date of Patent: May 23, 1995
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: Kathleen A. Hachey, Thomas P. Hedblom, David C. May
  • Patent number: 5286682
    Abstract: A pavement marking that has yellow-tinted, retroreflective beads partially embedded in a bead-carrier medium. The bead-carrier medium contains 0.5 to 15 volume percent of a light-scattering agent that scatters white light. The pavement marking is able to retroreflect a distinct yellow color at nighttime without using yellow pigments that contain the potentially-toxic metals, cadmium, chromium, and lead.
    Type: Grant
    Filed: February 19, 1992
    Date of Patent: February 15, 1994
    Assignee: Minnesota Mining and Manufacturing Company
    Inventors: Gregory F. Jacobs, James E. Lasch, Thomas P. Hedblom, Larry K. Stump
  • Patent number: 5227221
    Abstract: A polymeric base sheet has a plurality of protuberances and valleys located on a first side of the base sheet. A layer of bonding material is located on a top surface of the protuberances and is substantially absent from the valleys located between the protuberances. A plurality of skid-preventative particles are secured to the layer of bonding material so as to be substantially absent from the valleys. A sheet of this construction allows the skid-preventative particles to be used in a more efficient manner than heretofore known. By placing the skid-preventative particles exclusively on the protuberances of the base sheet, less particles need to be employed to obtain the skid-preventative surface.
    Type: Grant
    Filed: January 24, 1991
    Date of Patent: July 13, 1993
    Assignee: Minnesota Mining and Manufacturing Company
    Inventor: Thomas P. Hedblom
  • Patent number: 4988555
    Abstract: A retroreflector sheet comprising a base sheet and integral protrusions having a top and a side surface. Selected side surfaces are covered with a bead bond layer including partially embedded retroreflector beads. A process for preparing the retroreflector sheet is also disclosed.
    Type: Grant
    Filed: January 2, 1990
    Date of Patent: January 29, 1991
    Assignee: Minnesota Mining and Manufacturing Company
    Inventor: Thomas P. Hedblom
  • Patent number: 4988541
    Abstract: Process for making retroreflector sheet having protrusions which are retroreflective on selected side surfaces of the protrusions. Continuous web of polymeric base sheet having a front surface with a plurality, of protrusions, each protrusion having a top surface and at least one side surface, is provided. The web is conveyed through a nip in contact with a liquid film of bonding polymer at sufficient pressure to displace the film from the protrusion top surfaces and onto selected side surfaces, depending upon the relative speeds of the web and bonding polymer film. Retroreflective beads are applied to the liquid film which is then solidified (e.g., by temperature change) to hold the beads in place.
    Type: Grant
    Filed: January 2, 1990
    Date of Patent: January 29, 1991
    Assignee: Minnesota Mining and Manufacturing Company
    Inventor: Thomas P. Hedblom