Sign text display for vehicle navigation system

• US 5,974,357 A
• Filed: 12/19/1996
• Issued: 10/26/1999
• Est. Priority Date: 12/19/1996
• Status: Expired due to Term

• Current Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.), Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.), Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Ohashi, Mikio, Poonsaengsathit, Roderick A.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Donnelly, Arthur D.
• Application Number:
  US08/781,947
• Time in Patent Office: 1,041 Days
• Field of Search: 701/211, 701/201, 701/200, 701/206, 701/208, 701/209, 701/210, 340/996
• US Class Current: 701/210
• CPC Class Codes: G01C 21/3626 Details of the output of route guidance instructions traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968

Abstract

A vehicle navigation system for indication of the current vehicle position provides improved guidance to the driver when he is exiting from a freeway onto a freeway connector road segment (a freeway bifurcation), with the destination being a street (non-freeway road segment) linked to the freeway connector. In this case there is a possibility that the displayed sign text data at the first decision point upon exiting from the freeway does not correspond closely enough to the actual freeway signs, which tend to emphasize the connecting freeways rather than the street. This would tend to confuse the driver. Therefore, before the vehicle passes through the first decision point upon exiting the freeway, the sign text data for the freeway connector segment of the segment prior to the last freeway connector segment connecting to the destination street is displayed at the first guidance point, and not just the destination street. After the vehicle passes the first decision point on the freeway connector, if the sign text data for the last freeway connector segment on that set of freeway connectors is included in the sign text data for the freeway connector segment of one segment before the last road segment, the last sign text data is displayed; if not, the sign text data for the freeway connector segment of one segment before the last is displayed. Hence, the system reliably displays data indicating the freeway bifurcation onto which the driver wants to turn.

Claims

1. A method of displaying a guided route in a vehicle navigation system, the guide route being a linked series of road segments, the guided route including a destination street that is not a freeway and at least first and last road segments that are freeway connector road segments, there being stored sign text associated with the road segment, the method comprising the steps of:

(a) determining if the vehicle has passed a first decision point that is a bifurcation of a freeway on the guided route;

if it is determined that the vehicle has passed the first decision point, then;

(b) determining if a last freeway connector road segment on the guided route is designated in a sign text associated with a freeway connector road segment immediately prior to a last freeway connector road segment on the guided route;

(c) if step (b) is determined to be true, then displaying the sign text associated with a last freeway connector road segment on the guided route; and

(d) if step (b) is determined to be false, then displaying a sign text data associated with the freeway connector road segment immediately prior to the last freeway connector segment on the guided route.

2. The method of claim 1 wherein the sign text differs from an actual road sign associated with each of the road segments.

3. The method of claim 1, wherein a freeway connector road segment is any road segment so designated in a database of the road segments.

4. The method of claim 1, wherein the steps of displaying each include displaying visually.

5. The method of claim 1, wherein the steps of displaying each include announcing audibly.

6. A navigation system for displaying a guided route on a road network that is a series of linked road segments, the guided route including a destination street that is not a freeway and at least first and last road segments that are freeway connector road segments, the system comprising:

means for determining a current location of the vehicle;

means for determining if the current location of the vehicle is past a first decision point on a freeway on the guided route;

means for determining, if the vehicle has passed the first decision point, if a last freeway connector road segment on the guided route is designated in a sign text associated with a freeway connector road segment immediately prior to a last freeway connector road segment on the guided route;

means for displaying, if the vehicle is determined to be past the first decision point, the sign text associated with a last freeway connector road segment on the guided route; and

means for displaying, if the vehicle is determined not to be past the first decision point, a sign text associated with the freeway connector road segment immediately prior to a last freeway connector segment on the guided route.

7. The system of claim 6, wherein the sign text differs from an actual road sign associated with each of the road segments.

8. The system of claim 6, wherein a freeway connector road segment is any road segment so designated in a database of the road segments.

9. The system of claim 6, wherein the means for displaying include means for displaying visually.

10. The system of claim 6, wherein the means for displaying include means for announcing audibly.