Optics: measuring and testing – Angle measuring or angular axial alignment – Apex of angle at observing or detecting station
Reexamination Certificate
2001-05-24
2002-06-25
Buczinski, Stephen C. (Department: 3662)
Optics: measuring and testing
Angle measuring or angular axial alignment
Apex of angle at observing or detecting station
C356S004010, C359S226200, C180S169000
Reexamination Certificate
active
06411374
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light-projecting/receiving unit equipped with a scanning system; and, in particular, to an omnidirectional distance detecting apparatus, equipped with such a light-projecting/receiving unit, capable of detecting over 360 degrees therearound whether an object exists or not, the distance to the object, and the angle to the object.
2. Related Background Art
A distance detecting apparatus having a light projector using a laser, light-emitting diode, or the like for generating irradiation light to be emitted outside and a light receiver using a photodiode for detecting reflected light from an object and detects whether the object exists in a detecting direction or not and the distance to the object from the time difference between the light projection and light reception or the like has conventionally been known as a distance sensor system mounted in an automatic guided vehicle, for example.
The detecting direction in such an apparatus is the direction in which the irradiation light is projected outside and the reflected light from the outside is received. The detecting direction can be selected if the optical path of the irradiation light emitted from the light projector and the optical path of the reflected light made incident on the light receiver are changed to a predetermined direction by reflecting means such as a reflecting mirror which is optical path changing means. Here, the optical path changing means may be configured so as to be secured to and installed in a rotary mechanism which is rotatable by a predetermined rotary shaft, such that the detecting direction can be changed continuously, and the sidewall of surroundings of the optical path changing means being rotated may be configured optically open to the outside, such that the detecting direction can be rotated and changed substantially over 360 degrees therearound. As a consequence, an omnidirectional type distance detecting apparatus which can detect the distance to the object in all directions can be attained.
In an omnidirectional distance detecting apparatus such as the one mentioned above, the position of detected object can be specified if not only the distance to the object based on the light projection and reception but also the angle (direction) to the object is detected. Namely, while whether an object exists or not is detected according to whether reflected light is received from the object or not, if the reflected light is received, so that the object exists, then the distance to the object is detected according to the time difference between light projection and light reception or the like, and the angle to the object is detected by angle detection means, such as transmission type optical encoder, installed with respect to the rotary mechanism such that the angle of rotation in the detecting direction can be measured. Examples of such apparatus include those disclosed in Japanese Patent Application Laid-Open No. HEI 7-191142 and No. HEI 10-10233.
SUMMARY OF THE INVENTION
In the above-mentioned conventional omnidirectional distance detecting apparatus, while the optical path changing means is fixed onto a rotary shaft, the light projector and light receiver are disposed opposite each other on the rotary shaft so as to face their respective predetermined reflecting surfaces of the optical path changing means. Namely, the light projector is disposed at one end part of the rotary shaft, so as to emit irradiation light along the rotary shaft, and the optical path thereof is changed by optical path changing means, such as light projection mirror, to a detecting direction which is perpendicular to the rotary shaft, so that the light is emitted outside. On the other hand, the light receiver is disposed at the other end part of the rotary shaft, such that the optical path of the reflected light from the object incident in the detecting direction is changed by optical path changing means, such as light-receiving mirror, to a direction extending along the rotary shaft, whereby the light is incident on the light receiver.
Thus configured apparatus has been problematic in that, since the light projector and light receiver are installed at substantially both ends of the rotary shaft, i.e., both ends of the apparatus, a wire such as signal line becomes longer and limits the degree of freedom in designing the rotary mechanism and the like. Also, since this line is required to pass through a region where the projection of irradiation light to the outside and the reception of reflected light from the outside are carried out, complete 360-degree omnidirectional distance detection has been impossible. Further, such a longwire enhances the influence of electric noise from the rotary driving system of rotary mechanism and the like, thereby causing the accuracy of distance detection to deteriorate.
In view of the problems mentioned above, it is an object of the present invention to provide an omnidirectional distance detecting apparatus which enables distance detection over 360 degrees with a high accuracy.
For achieving such an object, the present invention provides an omnidirectional distance detecting apparatus, comprising a light projector and a light receiver within a housing, for emitting irradiation light from the light projector to a predetermined detecting direction outside the housing by way of projecting light optical path changing means and causing reflected light from an object in the detecting direction to be made incident on the light receiver by way of receiving light optical path changing means, so as to detect whether the object exists or not and a distance to the object; the apparatus comprising a rotary mechanism having a rotating part installed so as to be rotatable about a predetermined axis within the housing as an axis of rotation and a rotary driving part for driving the rotating part, the projecting light optical path changing means and receiving light optical path changing means being secured and installed on the axis of rotation; angle detection means for detecting an angle of rotation of the rotating part; and a signal processing circuit for detecting the distance to the object according to a signal from the light projector and light receiver and an angle to the object according to a signal from the angle detection means; a region within the housing being divided along the direction of axis of rotation into an optical system region and a driving system region within which the light projector, light receiver, and signal processing circuit are disposed, a side wall of the optical system region being constituted by a transparent tube transparent to light; the optical system region being further divided along the direction of axis of rotation into a light-projecting region, including the projecting light optical path changing means therein, for emitting the irradiation light into the detecting direction; and a light-receiving region adjacent the driving system region, including the receiving light optical path changing means therein, for receiving the reflected light from the detecting direction; the light-projecting region and light-receiving region being optically separated from each other by light-shielding means, installed so as to be fixed with respect to the transparent tube, for blocking stray light deviating from an optical path; the light receiver having irradiation light guiding means, disposed on the axis of rotation so as to oppose the receiving light optical path changing means and installed within the light-projecting region, for guiding the irradiation light from the light projector to the projecting light optical path changing means.
The present invention also provides an omnidirectional distance detecting apparatus, comprising a light projector and a light receiver within a housing, for emitting irradiation light from the light projector to a predetermined detecting direction outside the housing by way of projecting light optical path changing means and causing reflected light from an object in
Hirayanagi Michito
Kawai Takaaki
Nakase Shigeki
Tozuka Hiromichi
Buczinski Stephen C.
Hamamatsu Photonics K.K.
Morgan & Lewis & Bockius, LLP
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