Electromagentic wave generating device and a distance measuring device

• US 5,515,156 A
• Filed: 07/25/1994
• Issued: 05/07/1996
• Est. Priority Date: 07/29/1993
• Status: Expired due to Term

• Current Assignee: Omron Automotive Electronics Company Limited (Nidec Corporation)
• Original Assignee: Omron Corporation
• Inventors: Ishio, Wataru, Miyazaki, Hidenori, Yoshida, Masato, Tasaka, Yoshiro
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/279,428
• Time in Patent Office: 652 Days
• Field of Search: 356/5.01, 356/3.09, 356/6
• US Class Current: 356/5.01
• CPC Class Codes: G01S 2007/4975 of sensor obstruction by, e.g. dirt- or ice-coating, e.g. by reflection measurement on front-screen
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

A safety distance measuring device employing an electromagnetic wave is provided. A laser diode 2 is energized to emit laser beams by a laser diode drive circuit 3 in accordance with a clock signal generated by a control circuit 29. The emitted laser beams are sequentially changed to predetermined scanning directions by a scanner 1 associated with control circuit 29. The scanned laser beams from scanner 1 are reflected by an object 19 to be received by a photodiode 5. An output of the photodiode is applied to control circuit 29 through a light receiving circuit 6 where an elapsed time from emission to receipt is computed to obtain a distance from scanner 1 to object 19. Based on data relating to scanning directions by a scanning position detector 4, a begin-and-end detecting circuit 28 can stop the radiation of electromagnetic waves around a scanning start point and a scanning end point which is danger to human bodies.

Claims

1. A distance measuring device comprising

measurement electromagnetic wave scanning means for radiating a measurement electromagnetic wave with scanning from a scanning start point to a scanning end point,

electromagnetic wave detecting means for detecting the radiated measurement electromagnetic wave which is reflected on a reflection point of an object to be detected thereby,

operation means for measuring an elapsed time from emission to detection of the electromagnetic wave and for calculating a distance between said measurement electromagnetic wave scanning means and said reflection point based on the measured elapsed time, and

radiation attenuation means for attenuating the radiation of the measurement electromagnetic waves around said scanning start point and said scanning end point.

2. A distance measuring device according to claim 1, in which said radiation attenuation means is designed to cease the radiation of said measurement electromagnetic waves.

3. A distance measuring device according to claim 1 further including means for receiving a leakage beam from said measurement electromagnetic wave scanning means to confirm whether or not the function of said measurement electromagnetic wave scanning means is normal in view of level of the leakage beam.

4. A distance measuring device according to claim 1, in which said measurement electromagnetic wave scanning means is provided with a first transparent window disposed in an orbit of the measurement electromagnetic waves, receives a reflected beam of the radiated measurement electromagnetic wave reflected by said first transparent window to detect a dirt on the first transparent window in view of the level of the reflected beam, and adjusts the radiation output of said measurement electromagnetic wave scanning means based on a degree of the detected dirt.

5. A distance measuring device according to claim 2 in which said electromagnetic wave detection means is provided with a second transparent window disposed within the orbit of said measurement electromagnetic waves and inspection electromagnetic wave output means for generating an inspection electromagnetic wave during a radiation ceasing period of measurement electromagnetic waves around said scanning start and end points, the electromagnetic wave detection means being designed to receive the inspection electromagnetic wave generated by said inspection electromagnetic wave output means and reflected by said second transparent window and to detect dirts on the second transparent window during the radiation ceasing period of the measurement electromagnetic waves based on the level of the received inspection electromagnetic wave.

6. A distance measuring device according to claim 2 in which said electromagnetic wave detection means is provided with a second transparent window disposed within an orbit of said measurement electromagnetic wave and an inspection electromagnetic wave output means for generating an inspection electromagnetic wave during a radiation ceasing period of said measurement electromagnetic wave around the scanning start and end points, said electromagnetic wave detecting means being designed to receive the inspection electromagnetic wave generated by the inspection electromagnetic wave output means and reflected by the second transparent window and to detect based on the level of the received inspection electromagnetic wave whether or not the function of the electromagnetic detecting means is normal.

7. A distance measuring device comprising

measurement electromagnetic wave scanning means for radiating a measurement electromagnetic wave with scanning from a scanning start point to a scanning end point by changing a scanning angular speed,

electromagnetic wave detecting means for detecting said radiated measurement electromagnetic wave reflected by a reflection point of an object to be detected,

operating means for measuring an elapsed time from emission to detection of said measurement electromagnetic wave and for calculating a distance between said measurement electromagnetic wave scanning means and said reflection point based on the measured elapsed time, and

radiation level controlling means for controlling the radiation level of electromagnetic radiation means in proportion to the absolute value of a scanning angular speed.

8. An electromagnetic wave generating device comprising

electromagnetic wave emitting means for emitting an electromagnetic wave,

emission direction controlling means for controlling an emission direction of said electromagnetic wave emitted by said electromagnetic wave generating device,

angular speed detecting means for detecting an angular speed of the emission direction varied with said emission direction controlling means, and

electromagnetic wave power controlling means for decreasing an electromagnetic wave power emitted by said electromagnetic wave emitting means as the angular speed detected by said angular speed detecting means decreases.

9. An electromagnetic wave generating device according to claim 8 in which said emission direction controlling means scans said electromagnetic wave between a scanning start point and a scanning end point.

10. An electromagnetic wave generating device according to claim 8 in which said electromagnetic wave power controlling means turns the electromagnetic wave power emitted from said electromagnetic wave emitting means to zero when the angular speed detected by said angular speed detecting means is zero.

11. An electromagnetic wave generating device comprising

an electromagnetic wave emitter for emitting an electromagnetic wave,

an emission direction controller for controlling an emission direction of said electromagnetic wave emitted by said electromagnetic wave generating device,

an angular speed detector for detecting an angular speed of the emission direction varied with said emission direction controlling means, and

an electromagnetic wave power controller for decreasing an electromagnetic wave power emitted by said electromagnetic wave emitting means as the angular speed detected by said angular speed detecting means decreases.

12. A method of an electromagnetic wave emission comprising the steps of

emitting an electromagnetic wave,

controlling an emission direction of said electromagnetic wave emitted by said electromagnetic wave generating device,

detecting an angular speed of the emission direction varied with said emission direction controlling means, and

decreasing an electromagnetic wave power emitted by said electromagnetic wave emitting means as the angular speed detected by said angular speed detecting means decreases.