Optical electronic distance sensor with a parallel beam of light and adjustable detector-emitter separation

• US 4,346,293 A
• Filed: 04/07/1980
• Issued: 08/24/1982
• Est. Priority Date: 06/06/1979
• Status: Expired due to Term

• Current Assignee: Erwin SICK GmbH Optik-Elektronik
• Original Assignee: Erwin SICK GmbH Optik-Elektronik
• Inventors: Fetzer, Gunter
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US06/138,033
• Time in Patent Office: 869 Days
• Field of Search: 250/221, 250/222, 250/577, 250/216, 250/239, 356/1, 356/4
• US Class Current: 250/222.1
• CPC Class Codes: G01C 3/24 using a parallactic triangle with fixed angles and a base of variable length in the observation station, e.g. in the instrument
• CPC Class Codes: G01V 8/12 using one transmitter and one receiver
• CPC Class Codes: G08G 1/14 indicating individual free spaces in parking areas

Abstract

An optical electronic distance sensor utilizes a V-light barrier in which a light transmitter 11 transmits a substantially parallel light beam 14 at a defined angle and a light receiver 12 receives a substantially parallel light beam 15 at a defined angle and delivers an electrical output signal dependent on the intensity of the received light beam. The distance of the intersection of the transmitted and received light beam paths, i.e. the apex of the V, from the light transmitter and receiver defines the sensing distance of the light barrier and is adjusted by adjusting the separation of the light transmitter and receiver. For this purpose the light transmitter and receiver are displaceably mounted on a mounting rail. The distance sensor is particularly useful in indoor carparks for determining the presence or absence of a vehicle in a parking space.

Claims

1. V-light barrier apparatus for sensing the presence and absence of an object on a surface, comprising a straight mounting rail extending in a first direction, a light transmitter mounted on said rail and constructed to transmit a parallel beam of light along a transmitted beam path at a fixed and invariable angle relative to said rail, a light receiver mounted on said rail and constructed to receive a parallel beam of light along a received beam path at a fixed and invariable angle relative to said rail, with the transmitted beam path and the received beam path intersecting over an intersection region at a distance from said rail, means enabling movement of said light transmitter and said light receiver along said rail to adjust their relative separation, and thereby said distance, to bring said intersection region into coincidence with one of said surface and said object without varying the size or shape of said intersection region, and means for securing said light transmitter and said light receiver to said mounting rail.

2. Apparatus in accordance with claim 1 and wherein the mounting rail has a hollow cavity extending in its longitudinal direction for housing electrical connection cables for the light transmitter and receiver.

3. Apparatus according to claim 1, comprising a plurality of light transmitters and a plurality of light receivers, said transmitters being mounted on said rail alternately with said receivers to form a plurality of V-light barriers.

4. Apparatus in accordance with claim 1, wherein said mounting rail has a box profile and a guide slot along one side thereof and wherein said means enabling movement of said light transmitter and said light receiver comprises T-guides fixed to each of said light transmitter and light receiver, each of said T-guides being engageable in said box profile and slidable relative thereto.

5. Apparatus in accordance with claim 4, wherein said means for securing said light transmitter and said light receiver to said mounting rail comprises clamp screws associated with each of said light transmitter and light receiver for releasably clamping said light transmitting and said light receiver to said rail.

6. In optical electronic distance sensing apparatus including light transmitting means for directing transmitted light at a surface and light receiving means for receiving transmitted light reflected from said surface and providing an electrical signal in response thereto, the improvement wherein:

said light transmitting means transmits a substantially parallel beam of light in a first predetermined direction;

said light receiving means is sufficiently directional to receive a substantially parallel beam of light from a second predetermined direction;

said first and second predetermined directions are selected so that the range of resolved distances of said sensing apparatus has a predetermined magnitude; and

means for adjusting the axial separation of said light transmitting means and said light receiving means, whereby the separation of the range of resolved distances from the sensing apparatus can be varied.

7. Adjustable V-light barrier apparatus having a range of resolved distances of constant predetermined magnitude for sensing the presence or absence of an object on a surface, comprising:

light transmitter means producing a substantially parallel transmitted beam of light;

highly directional light receiving means for receiving a substantially parallel received beam of light; and

means for mounting said light transmitter means and said light receiving means in fixed, predetermined, angular relation to one another and in adjustable, spaced-apart relation to one another, said predetermined angular relation being selected so that said transmitted beam and said received beam intersect in a range of resolved distances equal to said predetermined magnitude, and said spaced-apart relation being adjustable to position said range of resolved distances at one of said surface and said object.