Patent ID: 9256952
Filing Date: 2016-02-09
CPC Classification: B60W,B60Y,B62J,G01P,G06T

Claim Text:
1. A vehicle speed calculator comprising: an image capturing unit attached to a vehicle, the image capturing unit configured to capture an image of a road surface on which the vehicle is traveling; a traveled distance detection unit which detects a traveled distance per unit time of a feature point in a shooting range captured by the image capturing unit in a shot image; a vehicle speed calculation unit which calculates a vehicle speed of the vehicle relative to the road surface from the traveled distance detected by the traveled distance detection unit; a reference distance mark irradiation unit which irradiates, to the road surface, a reference distance mark formed in such a manner as to have a reference distance from the vehicle in a longitudinal direction of the vehicle in the shooting range in parallel with an optical axis of the image capturing unit; and an image reference distance detection unit which detects an image reference distance, which is the longitudinal length of the reference distance mark irradiated by the reference distance mark irradiation unit in the shot image; wherein: the vehicle speed calculation unit calculates the vehicle speed from the traveled distance using the reference distance and the image reference distance detected by the image reference distance detection unit; the reference distance mark irradiation unit irradiates the reference distance mark in parallel with the optical axis of the image capturing unit; and the reference distance mark irradiation unit comprises at least two laser pointers that are arranged away from each other in the longitudinal direction of the vehicle.