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`Mercedes-Benz USA, LLC, Petitioner - Ex. 1009
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`M
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`WINDOW
`DEFINING
`MEANS
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`9.8._onam.~E...8
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`2
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`U.S. Patent
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`May 25, 1993
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`6
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`5,214,408
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`U.S. Patent
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`May 25, 1993
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`Sheet 3 of 5
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`5,214,408
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`4
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`U.S. Patent
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`Sheet 4 of 6
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`5,214,408
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`5
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`U.S. Patent
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`May 25, 1993
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`Sheet 5 of 6
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`5,214,408
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`330)
`On-«Z
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`U.S. Patent
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`May 25, 1993
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`Sheet 5 of 6
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`5,214,408
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`F I G . 8
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`PRIOR ART
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`SIG NAL
`PROCESSOR
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`7
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`1
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`DISTANCE DETECTING APPARATUS FOR A
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`VEHICLE
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`5,214,408
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`BACKGROUND OF THE INVENTION
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`invention relates to an apparatus for
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`optically measuring the distance from a vehicle to ob-
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`jects such as obstacles lying ahead thereof as well as
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`other vehicles which are travelling ahead of the vehicle
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`or approaching it from behind.
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`Some examples of an obstacle detecting apparatus are
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`disclosed in Japanese Patent Laid-Open 55-15337 and
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`Japanese Utility Model Laid-Open 1-12221. These ap-
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`paratuses project ultrasonic waves or electromagnetic
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`waves in a specified forward or backward direction to
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`be detected and receive reflected waves from an object
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`or obstacle for the purpose of determining the presence
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`or absence of an obstacle as well as measuring the dis-
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`tance thereto.
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`Examples of an optical distance detecting apparatus
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`utilizing image sensors are known from Japanese Patent
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`Publication Nos. 63-38085 and 63-46363. As illustrated
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`in FIG. 8, the apparatuses disclosed therein commonly
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`have a pair of first and second parallel optical systems
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`having two convex lenses 101, 102 disposed in a hori-
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`zontally aligned relation at a prescribed distance L
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`away from each other. A pair of separate image sensors
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`103, 104 are horizontally disposed at focal points of the
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`lenses 101, 102 at a distance f from the locations of 30
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`corresponding lenses 101, 102, respectively, for generat-
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`ing respective image signals to a common signal proces-
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`sor 120. The signal processor 120 successively shifts the
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`image signals from the image sensors 103, 104 and elec-
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`tiically superposes them one over the other, so that the
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`distance R from the lenses 101, 102 to an object 121 is
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`calculated based on the principle of triangulation using
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`the following formula:
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`R=(/X1.)/d
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`where d is a shift distance by which the image signals
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`are moved to obtain the best match.
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`In
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`63-18122 discloses an obstacle detecting apparatus for a
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`vehicle which is provided with a plurality of light emit-
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`ting elements or light transmitters each projecting a
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`beam of light toward objects to be detected for the
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`purpose of improving the contrast of the image of an
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`object sensed by the image sensors in the event that no
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`good image contrast is obtained.
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`With the distance and/or obstacle detecting appara-
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`tuses as described above,
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`is possible to detect the
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`presence or absence of an object lying in the direction in
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`which ultrasonic or electromagnetic waves or light are
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`projected, but
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`whether the object thus detected is an obstacle to the
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`travel of the vehicle. For example, when a vehicle is
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`travelling on a curved road, the obstacle detecting ap-
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`paratus mounted thereon can rnisidentify a guide rail,
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`which is set up along one side or shoulder of the curved
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`road and lies ahead of the cornering vehicle, as an obsta-
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`cle. In addition, in order to exactly determine the loca-
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`tion and direction of the object detected with respect to
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`the moving vehicle, many ultrasonic or electromagnetic
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`wave transmitters and receivers are required, thus re-
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`sulting in a great increase in size and costs of manufac-
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`ture of the overall apparatus.
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`Moreover, if there are many objects within the field
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`of view of the image sensors,
`is unclear to which
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`object the distance from the subject vehicle is being’
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`detected. In particular, let us assume that the distance to
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`an object in the form of a preceding vehicle is detected
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`by the above-described distance detecting apparatus
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`mounted on the subject vehicle during the travel
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`thereof. In this case, if another vehicle travelling on one
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`of plural lanes of a road adjacent the one on which the
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`subject vehicle is travelling comes into the field of view
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`of the image sensors, it is not clear at all or the driver
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`cannot tell to which vehicle (i.e., travelling on the same
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`lime or on an adjacent lane) the distance is detected.
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`Furthermore, in cases where the brightness or magni-
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`tude of external light is insufficient for proper distance
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`detection by image sensors such as when the vehicle
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`travels in a tunnel or in dark weather such as in the
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`evening, twilight, etc., it is necessary to use a light emit-
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`ting element which projects a beam of visible light
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`toward a preceding vehicle. In this case, however, there
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`is a fear that the passengers including the driver in the
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`preceding vehicle are dazzled by the light from the light
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`emitting element, making it difficult for the driver to
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`properly maneuver his or her vehicle in a safe manner.
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`SUMMARY OF THE INVENTION
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`Accordingly,
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`invention is intended to
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`overcome the above-mentioned problems encountered
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`with the conventional apparatuses.
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`An object of the invention is to provide a novel and
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`improved distance detecting apparatus for a vehicle in
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`which the driver is able to readily and exactly recognize
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`the location and direction of each object present within
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`the wide field of view of the driver, and at the same time
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`determine whether each of the objects is an obstacle to
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`the travel of his or her vehicle as well.
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`Another object of the invention is provide a novel
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`and improved distance detecting apparatus for a vehicle
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`which is able to concurrently detect the distances to a
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`plurality of objects which exist within the field of view
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`of the driver, and in which the driver is able to readily
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`and accurately recognize to which objects the distances
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`are detected.
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`A further object of the invention is to provide a novel
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`and improved distance detecting apparatus for a vehicle
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`which is able to sense a preceding vehicle running
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`ahead of a subject vehicle on which the apparatus is
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`mounted without dazzling the passengers in the preced-
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`ing vehicle even when travelling in a tunnel or in dark
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`weather such as in the evening, twilight and the like.
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`In order to achieve the above objects, according to
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`the present invention, there is provided a distance de-
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`tecting apparatus for a vehicle comprising: a pair of first
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`and second image sensors including a pair of optical
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`systems for optically sensing a plurality of objects; a
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`first memory for storing the images of the objects
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`sensed by the first image sensor as first image signals; a
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`second memory for storing the images of the objects
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`sensed by the second image sensor as second image
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`signals; a display with a screen for displaying the images
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`of the objects as sensed by the image sensors on the
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`screen; window defining means for defining a plurality
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`of windows at specific locations on the screen of the
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`display; distance calculating means for electrically de-
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`tecting deviations between the images of the objects
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`within the respective windows as sensed by the image
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`sensors and individually calculating the distance to each
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`object in each window based on the calculated devia-
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`3
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`tions; and obstacle discriminating means for discriminat-
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`ing, among the objects around the vehicle as sensed by
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`the image sensors, obstacles to the travel of the vehicle
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`on the basis of the positions of the windows on the
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`screen and the distances to the objects in the respective
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`windows as detected.
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`The window defining means defines the plurality of
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`windows in such a manner that the windows are dis-
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`posed on the screen of the display in a horizontally
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`separate relation with respect of each other, the win-
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`dows including a central window located at the center
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`of the screen, and a plurality of side windows located on
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`the opposite sides of the central window. The obstacle
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`discriminating means determines that the image in the
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`central window is the image of a preceding vehicle
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`which a vehicle having the apparatus installed thereon
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`follows.
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`Preferably, the apparatus further comprises means for
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`determining, based on the rate of change of the dis-
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`tances as measured by the distance calculating means,
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`whether an object displayed in each window is coming
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`near or going away from a vehicle on which the appara-
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`tus is installed.
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`Preferably, a vehicle condition sensing means is pro-
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`vided for determining whether a subject vehicle having
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`the apparatus installed thereon is travelling on a curved
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`road. The obstacle discriminating means operates to
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`determine that the objects displayed in the windows are
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`not obstacles impeding the travel of the subject vehicle,
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`if it is determined that the subject vehicle is travelling
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`on a curved road and if the distances to the objects
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`displayed in the windows vary in a gradually decreasing
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`or increasing manner in a horizontal direction from one
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`side to the other side of the windows.
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`An infrared light generating means can be provided
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`for projecting a beam of infrared light toward objects
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`present within the fields of View of the image sensors
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`when natural visible light is insufficient for the image
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`sensors. In this case, the image sensors are sensitive to
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`infrared light as well.
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`The above and other objects, features and advantages
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`of the invention will become more readily apparent
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`from the detailed description of a few preferred embodi-
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`ments of the invention taken in conjunction with the
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`accompanying drawings.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`FIG. 1 is a schematic block diagram showing the
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`general arrangement of a distance detecting apparatus
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`for a vehicle in accordance with the present invention;
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`FIG. 2 is an explanatory view showing a plurality of
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`windows defined on the screen of a display;
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`FIG. 3 is an explanatory view showing that a plural-
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`ity of preceding vehicles running ahead of a vehicle
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`come into some of the windows;
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`FIGS. 4(a) and 4(b) are explanatory views showing
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`image areas to be compared with reference images each
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`within a corresponding window;
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`FIG. 5 is an explanatory view showing images dis-
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`played on the screen when the vehicle is travelling on a
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`curved road;
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`FIG. 6 is a view showing that the positions of win-
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`dows on the screen are altered;
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`FIG. 7 is a view similar to FIG. 1, but showing an-
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`other embodiment of the invention; and
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`FIG. 8 is a block diagram showing the general ar-
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`rangement of a conventional distance detecting appara-
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`tus for a vehicle.
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`In the figures, the same or corresponding parts are
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`identified by the same symbols.
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`DESCRIPTION OF THE PREFERRED
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`EMBODIMENTS
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`A few preferred embodiments of the present inven-
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`tion will now be described in detail with reference to
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`the accompanying drawings.
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`FIG. 1 illustrates, in a block diagram, the schematic
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`arrangement of a distance detecting apparatus which is
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`constructed in accordance with the principles of the
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`invention and which is mounted on a vehicle for detect-
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`ing the distances to objects such as preceding vehicles,
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`obstacles and the like lying ahead of the subject vehicle.
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`The apparatus illustrated includes a pair of first and
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`second parallel optical systems having two convex
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`lenses 1, 2 disposed in a vertically aligned relation at a
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`prescribed distance L away from each other, and a pair
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`of separate first and second (e.g., upper and lower)
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`image sensors 3, 4 which are vertically or otherwise
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`disposed at focal points of the lenses 1, 2, respectively,
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`at a distance f from the locations of the corresponding
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`lenses 1, 2 for generating first and second image signals
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`mensional image, which are input to a pair of corre-
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`sponding first and second analog-to-digital (A/D) con-
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`verters 6, 7. The outputs of the A/D converters 6, 7 are
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`input to a pair of corresponding first and second memo-
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`ries 8, 9 and stored therein. A microcomputer 10, which
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`acts as a distance calculating means and an obstacle
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`discriminating means of the invention, performs data
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`transfer with the memories 8, 9 so that it makes various
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`calculations and determinations based on the data
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`stored in the memories 8, 9. A display 11 having a
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`screen is connected to the first and second memories 8, ,
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`9 and the microcomputer 10 for displaying the images
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`of objects sensed by the first or second image sensor 3,
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`4 on the screen. The operation of the display 11 is con-
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`trolled by the microcomputer ltl. A window defining
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`means 12 is connected to the microcomputer 10 for
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`defining on the screen of the display 11 a plurality of
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`windows which can be utilized for designating a plural-
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`ity of objects for distance measurements. More specifi-
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`cally, as shown in FIG. 2, the driver of a vehicle can
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`manipulate the window defining means 12 to define a
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`plurality (e.g., five in the illustrated embodiment) of
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`windows 15 through 19 on the screen of the display 11
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`at horizontally spaced or separate predetermined loca-
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`tions thereof while looking at the screen. A vehicle
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`condition sensing means 13 in the form of a steering
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`angle sensor senses the amount or angle of steering
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`representative of the rotational angle of a steering
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`wheel of the vehicle and generates a corresponding
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`steering angle signal to the microcomputer 10. An alarm
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`14 in the form of a buzzer is actuated by the microcom-
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`puter 10 to generate a warning when the distance to an
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`object 5 such as a preceding vehicle decreases to a
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`predetermined level.
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`The operation of the above embodiment will be de-
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`scribed below while referring to FIGS. 2, 3 and 4(a) and
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`4(b). First, assume that an object in the form of a pre-
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`ceding vehicle 5 lying ahead of the subject vehicle is
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`sensed by the second or upper image sensor 4, digitized
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`by the second A/D converter 7, stored in the second
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`memory 9, and then displayed on the screen of the
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`display 11, as shown in FIG. 3. In this case, the mi-
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`crocomputer 10 reads out from the second memory 9
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`picture element signals within the central window 17
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`9
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`that catches the preceding vehicle 5, and takes them as
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`reference image signals, which are used as a basis for
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`calculating the distance to the preceding vehicle 5.
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`Then, the microcomputer 10 selects a specific area cor-
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`responding to the window 17 from the first memory 8,
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`which stores image signals of objects sensed by the first
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`or lower image sensor 3. Then, the microcomputer 10
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`calculates a total sum of the absolute values of the dif-
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`ferences or deviations between the corresponding
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`image signals for the first and second picture elements
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`stored in the first and second memories 8, 9 while verti-
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`cally shifting the image signals from the first memory 8
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`relative to the above defined reference image signals in
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`a stepwise manner one picture element by one picture
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`element. In other words, by sequentially shifting the
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`second memory image signals one picture element by
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`one picture element, the best position of the image of
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`the object in the first memory 8 is determined in which
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`the image in the first memory 8 best matches the refer-
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`ence image. Thus, the amount of shift or shift distance
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`of the second memory image 5a relative to the reference
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`image is calculated which minimizes the total sum of the
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`absolute values of the deviations.
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`In this connection, it is to be noted that the area in the
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`first memory 8 relating to the above calculation is a
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`vertically extending band area 22, as shown in FIG.
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`4(b), which corresponds to the position of the window
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`17 in which the reference image exists, as shown in FIG.
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`4(a)-
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`Using the amount of shift n in terms of the number of
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`picture elements as calculated above, the distance R to
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`the preceding vehicle 5 is calculated as follows:
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`(1)
`R=(/><L)/nP
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`where f is the focal distance of the first and second
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`lenses 1, 2; L is the distance between the centers of the
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`first and second lenses 1, 2; n is the amount of shift
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`represented by the number of picture elements for mini-
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`mizing the total sum of the absolute values of the devia-
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`tions between the first and second picture elements in
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`the first and second memories 8, 9; and P is the vertical
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`pitch between adjacent picture elements in a vertical
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`array.
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`In this manner, the distance R to the object 5 imaged
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`in the window 17 can be measured. Likewise, if another
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`vehicle 25 running on an adjacent lane of the road ahead
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`of the subject vehicle comes into the fields of view of
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`the image sensors 3, 4 and is displayed on the screen of
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`the display 11 inside the window 19, as illustrated in
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`FIG. 3, the microcomputer 10 takes the image signals
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`inside a window 19 as reference picture signals as
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`shown in FIG. 4(a), selects an image area 24 in the first
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`memory 8 corresponding to the image signals of the
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`second memory 9 inside the window 19, and determines
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`the position of the image of the vehicle 25 in the first
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`memory 8 which provides the best match with the
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`image inside the window 19. Then, using equation (1)
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`above, the distance to the other vehicle 25 is calculated
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`in the same manner.
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`In this manner, even in cases where there are a plural-
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`ity of preceding vehicles running ahead of the subject
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`vehicle,
`is possible to concurrently detect the dis-
`it
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`tances to the respective preceding vehicles.
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`As can be seen from the foregoing, the objects caught
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`in the plurality of windows 15 through 19 defined on
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`the screen of the display 11, as shown in FIG. 4(a), are
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`compared with the images thereof in the calculation
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`areas of the memory 8 corresponding to the windows 20
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`through 21,
`respectively, as shown in FIG. 4(b),
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`30
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`45
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`65
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`5,214,408
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`6
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`whereby the distances to the respective objects can
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`substantially concurrently be measured using the indi-
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`vidual windows 15 through 19.
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`Further, if it is detected from the output signal of the
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`steering angle sensor 13 that the subject vehicle is run-
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`ning straight, it is determined that the vehicle displayed
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`on the screen 11 in the center thereof is a preceding
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`vehicle travelling on the same lane of a road as that on
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`which the subject vehicle is travelling. Accordingly, if
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`the distance from the subject vehicle to the preceding
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`vehicle becomes short or decreases to a predetermined
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`the microcomputer 10 actuates the alarm 14,
`level,
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`warning the driver of the presence of an obstacle in the
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`form of the preceding vehicle lying ahead of the subject
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`vehicle.
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`On the other hand, when the subject vehicle is travel-
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`ling on a curved road 26, e.g., a left-hand curve, the
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`image of a guide rail 27, which lies ahead of the vehicle
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`and is set up on one side or shoulder of the road 26, is
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`displayed on the screen 11. In this case, too, the dis-
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`tances to the respective portions of the guide rail 27
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`caught in the respective windows 15 through 19 are
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`detected or measured in the same manner as in the case
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`of the preceding vehicle. On this occasion, the distances
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`as detected by the right-side windows 18, 19 lying to the
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`right of the central window 17 in the center of the
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`screen 11 are shorter than that detected by the central
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`window 17, whereas the distances as detected by the
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`left-side windows 15, 16 are longer than that detected
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`by the central window 17. Accordingly, if such infor-
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`mation is obtained during the time when the steering
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`angle sensor 13 senses a left-hand steering operation of
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`the driver, the microcomputer 10 determines that an
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`object caught in the central window 17 on the screen 11
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`is not an obstacle impeding the travel of the vehicle. As
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`a result, even if the distance detected by the central
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`window 17 is short,
`it is determined that there is no
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`problem, and hence the alarm 14 is not actuated. In this
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`manner, on the basis of the information on the distances
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`to objects ahead of the subject vehicle as detected by
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`the respective windows 15 through 19, it can be pre-
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`cisely determined whether the objects as detected and
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`displayed by the respective windows 15 through 19 are
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`true obstacles to the travel of the subject vehicle.
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`Although in the above embodiment, five windows 15
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`through 19 are set on the screen, the number of such
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`windows can be arbitrarily selected depending on the
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`dimensions of objects within the fields of view of the
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`image sensors 3, 4, the number of objects to which
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`distance measurements are required, etc. Also, the size
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`and configuration of each window can be arbitrarily
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`changed according to an object to be detected. In addi-
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`tion, the positions of windows as set on the screen 11
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`can be varied according to ranges or fields to be de-
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`tected, as shown in FIG. 6. Moreover, the present in-
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`vention can be applied for detecting or supervising
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`objects present in the rear vision of a vehicle. Further,
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`according to the invention, it is possible to calculate the
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`rate of change of the distance to an object caught by
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`each of the windows 15 through 19 so as to determine
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`whether or not the object is coming near or going away
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`from the subject vehicle.
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`In addition, although in the above embodiment, the
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`lenses 1, 2 and the image sensors 3, 4 are disposed in a
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`vertically aligned and spaced relationship with respect
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`to each other, they may be disposed in a modified man-
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`ner, e.g., diagonally on a vertical plane, such that they
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`10
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`are disposed substantially vertically. Obviously, such a
`components does not cause any dazzling or blinding of
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`modified arrangement provides substantially the same
`the driver or passengers in the preceding vehicle 5, so
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`results.
`the driver in the preceding vehicle can maneuver his or
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`FIG. 7 shows another embodiment of the invention.
`.her vehicle without any resultant trouble or inconve-
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`nience.
`This embodiment is substantially similar to the previous
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`Although in the above description, the infrared light
`embodiment of FIG. 1 except for the following. An
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`generating means comprises a combination of the light
`infrared light generating means is provided for project-
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`generator 30 and the infrared light filter 31,
`it is not
`ing a beam of infrared light to objects for detecting
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`them in dark weather in which there is insufficient natu-
`limited to such an arrangement but may take any other
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`ral visible light. The infrared light generating means
`appropriate form which can generate a beam of infrared
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`light while excluding almost all of the visible light com-
`comprises a light generator 30 in the form of a halogen
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`ponents.
`lamp for generating a beam of light including visible
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`What is claimed is:
`light components and infrared light components, and an
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`infrared light filter 31 for filtering or removing almost
`1. A vehicle mounted distance detecting apparatus,
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`all of the visible light components from the light gener- 15 comprising:
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`a) a pair of laterally spaced first and second image
`ated by the light generator while passing infrared light
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`sensors (3,4; 3'4’) including a pair of optical systems
`components alone. The infrared light beam projected
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`from the light generator 30 through the filter 31 to an
`(1, 2) for optically sensing a plurality of objects;
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`object 5 is reflected from a surface thereof and received
`b) a first memory for storing the images of said ob-
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`by a pair of first and second image sensors 3’, 4' through
`jects sensed by said first image sensor as first image
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`respective lenses 1, 2. The image sensors 3', 4' are sensi-
`signals;
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`tive to infrared light as well as visible light. Like the
`c) a second memory for storing the images of said
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`previous embodiment, the images of the object 5 thus
`objects sensed by said second image sensor as sec-
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`sensed by the image sensors 3’, 4’ are stored in corre-
`ond image signals;
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`sponding memories 8, 9 and then processed by a mi-
`cl) a display (11) with a screen for displaying the
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`crocomputer 10 in the same manner as in the previous
`images of said objects as sensed by said image sen-
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`sors on the screen;
`embodiment. The image of the object 5 sensed by the
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`second image sensor 4' is displayed on the screen of a
`e) window defining means (12) for defining a plurality
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`display 11 within a plurality of windows which are
`of windows (15-19) at specific locations on the
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`appropriately set thereon in advance. In this connec-
`screen of said display;
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`tion, the light generator 30 projects a light beam toward
`0 distance calculating means for electrically detect-
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`the object 5 with an angle of projection B which is set
`ing deviations between the images of said objects
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`within the respective windows as sensed by said
`to be less than the angle of field A of the image sensors
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`3’, 4’ through the lenses 1, 2, as shown in FI