Device for distance measurement

• US 7,002,669 B2
• Filed: 08/09/2002
• Issued: 02/21/2006
• Est. Priority Date: 08/09/2001
• Status: Expired due to Fees

• Current Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Original Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Inventors: Frick, Rainer
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): ALSOMIRI, ISAM A
• Application Number:
  US10/485,699
• Publication Number:
  US 20040222366A1
• Time in Patent Office: 1,292 Days
• Field of Search: None
• US Class Current: 356/4.01
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G02B 26/12 using multifaceted mirrors

Abstract

The invention relates to a device with a detector element for receiving a light beam reflecting on an object, wherein means for detecting the light beam are provided in the detector element. The invention also relates to a method for distance measurement using said receiver device. A device for determining the distance between a vehicle and an obstacle or a vehicle driving ahead is already known as per DE 197 13 826 A1, wherein a pulsed laser beam serving as send signal scans line-by-line a two-dimensional area using a self-rotating polygonal mirror, wherein said polygonal mirror has a plurality of mirror surfaces that are bent at different angles. The pulse beam reflecting on the object is focused on a detector element by optical lenses. Said device known in prior art requires a polygonal mirror that is complicated to produce and a complicated evaluation electronics due to the fact that, inter alia, the scanning impulses for the control of the laser diode have to be synchronized with the angular position of the polygonal mirror. The invention provides for a self-rotating polygonal mirror with a plurality of mirror surfaces that are bent at a given angle against the rotational axis of said polygonal mirror as receiver device so that the reflecting light beam is deflected in said mirror surfaces by means of an optics system and focused on the detector element.

Claims

1. An apparatus (1) with a detector element (9) for receiving a light beam (3a, 3b) reflected by an object, whereby means (7, 5) are provided for deflecting the reflected light beam (3b) onto said detector element (9), characterized in that a rotating polygonal mirror (5) is provided as a means for deflecting the reflected light beam (3b), said polygonal mirror having a plurality of mirror surfaces (5a, 5b, 5c) inclined at an angle (β

) to the rotation axis (6) of the rotating polygonal mirror (5), whereby the detector element (9) is arranged in the direction of the rotation axis (6) of the polygonal mirror (5), and that an optic (7) is allocated to each mirror surface (5a, 5b, 5c) of the polygonal mirror (5) for focusing the reflected light beam (3b) onto the detector element (9), said optic rotating in synchronism with the polygonal mirror (5).

2. The apparatus of claim 1, characterized in that the optic (7) is constructed as a lens system.

3. The apparatus of claim 1, characterized in that the optics (7a, 7b, 7c) are arranged approximately along a circular line around the rotation axis of the polygonal mirror (5) and that screens (8) are provided between neighboring optics (7a, 7b, 7c) on the circular line.

4. The apparatus of claim 3, characterized in that for a polygonal mirror (5) with three, four or five mirror surfaces (5a, 5b, 5c), the screen (8) produces for the mirror surfaces (5a) a respective opening angle (α

) of 60°

.

5. The apparatus of claim 1, characterized in that the polygonal mirror (5) comprises at least three mirror surfaces (5a, 5b, 5c).

6. A method for distance measuring by means of the apparatus according to claim 1, characterized in that a continuously emitted and modulated light beam (3a) irradiates a space range (4) to be monitored, and that by phase comparing of this modulated light beam (3a) with the detected light beam (3b) the distance to an object present in the space range (4) to be monitored is determined and with the angular attitude of the polygonal mirror (5) the position of the object is determined.

7. The method of claim 6, characterized in that a pseudo-noise signal train is used for modulating the light beam (3a).