Optoelectronic distance measuring device

• US 6,710,324 B2
• Filed: 10/25/2002
• Issued: 03/23/2004
• Est. Priority Date: 10/29/2001
• Status: Expired due to Term

• Current Assignee: Sick AG (Sick)
• Original Assignee: Sick AG (Sick)
• Inventors: Hipp, Johann
• Primary Examiner(s): Porta, David
• Assistant Examiner(s): Meyer, David C.
• Application Number:
  US10/281,288
• Publication Number:
  US 20030080285A1
• Time in Patent Office: 515 Days
• Field of Search: 330/59, 330/308, 250/214.A, 250/559.38, 250/214.LA, 250/214.R, 250/214.LS, 250/559.29, 356/3, 356/4.01, 356/5.01, 356/5-2-
• US Class Current: 250/214.00A
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/4861 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: G01S 7/4868 Controlling received signal intensity or exposure of sensor
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection

Abstract

An optoelectronic distance measuring device has at least one transmitter unit to transmit pulsed electromagnetic radiation, at least one receiver unit associated with the transmitter unit to receive the reflected radiation and an evaluation unit to determine at least the distance of objects reflecting the transmitted radiation, with a series connection of load resistors being connected after the receiver unit and a separate amplifier being associated with each load resistor to amplify the subsidiary pulse produced at the respective load resistor from an incoming, successively attenuated received pulse.

Claims

1. An optoelectronic device, for measuring the distance of objects comprising

at least one transmitter unit to transmit pulsed electromagnetic radiation;

at least one receiver unit, associated with the transmitter unit to receive reflected radiation;

an evaluation unit to determine at least the distance of the objects reflecting the transmitted radiation; and

a series connection of load resistors connected after the receiver unit and a separate amplifier associated with each load resistor to amplify a subsidiary pulse created at the respective load resistor from an incoming, successively attenuated received pulse.

2. A device in accordance with claim 1, wherein the resistance values of the load resistors reduce successively starting from the receiver unit.

3. A device in accordance with claim 1 wherein the ratios of the resistance values of the load resistors among one another are matched to the dynamic ranges of the amplifiers.

4. A device in accordance with claim 1 wherein the resistance values of the load resistors are selected such that a quotient of two successive sums of resistance values in each case corresponds to the dynamic range of the following amplifier.

5. A device in accordance with claim 4 comprising at least first, second and third successively arranged load resistors, and wherein the load resistance value of the second load resistor is selected so that the quotient of the sums of the load resistance values of the first and second load resistors corresponds to the dynamic range of the amplifier following the second load resistor.

6. A device according to claim 5 wherein the load resistance value of the third load resistor is selected so that the quotient of the sums of the load resistance values of the second and third load resistors corresponds to the dynamic range of the amplifier following the third load resistor.

7. A device according to claim 6 including a selection unit operatively coupled with the amplifier which selects the lowest amplified subsidiary pulse exceeding a reference voltage for further processing.

8. A device in accordance with claim 6 including means for using each amplified subsidiary pulse exceeding a reference voltage to switch off the next larger amplified subsidiary pulse and thereby prevent the next larger subsidiary pulse from being further processed.

9. A device in accordance with claim 1 wherein all amplifiers have the same dynamic range.

10. A device in accordance with claim 1 including a comparator with a predetermined reference voltage connected after each amplifier, the reference voltage corresponding to a respective reference threshold of a downstream selection unit connected to the comparators.

11. A device in accordance with claim 10 wherein an individual reference voltage is provided for each comparator.

12. A device in accordance with claim 1 including a common selection unit connected after the amplifiers for selecting at least one amplified subsidiary pulse from the incoming amplified subsidiary pulses which can be forwarded to a downstream evaluation unit for evaluation.

13. A device in accordance with claim 12 wherein a smallest amplified subsidiary pulse exceeding a respective reference threshold can be selected by the selection unit.

14. A device in accordance with claim 12 wherein the selection unit is made such that every amplified subsidiary pulse exceeding a respective reference threshold suppresses the evaluation of at least one larger amplified subsidiary pulse.

15. A device in accordance with claim 1 comprising a laser scanner.

16. A device in accordance with claim 14 wherein the selection unit suppresses a next larger, amplified subsidiary pulse.

17. A device according to claim 12 wherein the incoming amplified subsidiary pulses comprise parallel pulses.

18. A device according to claim 12 wherein the downstream evaluation unit evaluates a transit time of the subsidiary pulse.

19. A device in accordance with claim 1 wherein the at least one receiver unit comprises a photodiode.

20. A device in accordance with claim 1 wherein the evaluation unit uses a pulse transit time process.

21. A device according to claim 12 wherein the common selection unit is adapted to select precisely one amplified subsidiary pulse remaining below an overmodulation threshold.