Distance measuring equipment

• US 5,504,570 A
• Filed: 02/01/1994
• Issued: 04/02/1996
• Est. Priority Date: 02/12/1993
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Akasu, Masahira
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US08/189,713
• Time in Patent Office: 791 Days
• Field of Search: 356/5.01, 356/5.03, 356/5.05, 356/5.08, 180/167, 180/169
• US Class Current: 356/5.05
• CPC Class Codes: G01S 17/14 wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters

Abstract

Disclosed is a distance measuring apparatus having a clock generating element, a light emitting element, a light receiving element, a sample pulse generating element, a sample hold element and a processing element. The clock generating element generates a clock pulse at a predetermined time interval. The light emitting element generates a pulse beam in synchronism with the clock pulse. The light receiving element receives a reflected pulse beam from an object and converts it into an electric signal. The sample pulse generating element generates a sample pulse at a timing delayed by a predetermined minute time from a generating time of the clock pulse within one measuring period. The sample hold element effects sampling of an output signal from the light receiving element with the sample pulse. The processing element calculates a distance to the object by detecting it from the output signal of the sample hold element and from the delay time of the sample pulse. The processing element stops a generation of the pulse beam by the light emitting element with the measuring period determines an existence or non-existence of interference from the other light source exclusive of the light emitting element.

Claims

1. A distance measuring apparatus comprising:

a clock generating means for generating a clock pulse at a predetermined time interval;

a light emitting means for generating a pulse beam in synchronism with the clock pulse;

a light receiving means for receiving a reflected pulse beam from an object with respect to the pulse beam generated from said light emitting means and converting the reflected pulse beam into an electric signal;

a sample pulse generating means for generating a plurality of sample pulses, each corresponding to a respective said clock pulse, at a timing delayed in sequence by a respective predetermined time from a generating time of said respective clock pulse within one measuring period which is a predetermined period during which a plurality of said clock pulses are generated;

a sample hold means for sampling an output signal from said light receiving means by use of the sample pulses and outputting a sample hold output signal; and

a processing means for calculating a distance to said object by detecting a presence of said object based on the sample hold output signal and the delay time of the sample pulse which resulted in said sample hold means outputting said sample hold output signal, and stopping generation of the pulse beam by said light emitting means for stopping period after receiving said sample hold output signal and determining an existence or non-existence of interference from another light source exclusive of said light emitting means on the basis of an output from said sample hold means which occurs during the stopping period.

2. The distance measuring apparatus according to claim 1, further comprising an outputting means for outputting the distance to said object which has been calculated by said processing means.

3. The distance measuring apparatus according to claim 2, wherein said processing means causes said outputting means to output information indicating that the calculated distance is invalid when determining that there exists an interference from the another light source.

4. The distance measuring apparatus according to claim 1, wherein said processing means detects said object by comparing said sample hold output signal with a thereshold value.

5. A distance measuring apparatus comprising:

a light emitting means for generating a pulse beam at a light emission timing in synchronism with a clock pulse in a direction of an object to be measured;

a light receiving means for receiving an incident beam including the pulse beam reflected by the object to be measured;

a distance measuring means for calculating a distance to the object by measuring a time from emission of the pulse beam to receipt of the incident beam;

a light emission stopping means for stopping the emission of the pulse beam at at least a next light emission timing after said distance measuring means calculates a distance; and

an interference detecting means for determining an existence or non-existence of interference light in the incident beam on the basis of light received by said light receiving means during a period at which the emission of the pulse beam is stopped.

6. The distance measuring apparatus according to claim 5, wherein said interference detecting means determines that an interference light exists when said light receiving means receives light during a period at which the emission of the pulse beam is stopped.

7. The distance measuring apparatus according to claim 5, wherein said interference detecting means stores light intensity data received by said light receiving means during the measurement of a distance by said distance measuring means, and determines an existence or non-existence of interference light in the incident beam by comprising an intensity of light received by said light receiving means during a period at which the emission of the pulse beam is stopped with the stored intensity data.