Distance measuring device, distance measuring system, distance measuring method, and non-transitory storage medium

Patent metadata

Field	Value
Publication number	US-2022011437-A1
Application number	US-202117486863-A
Country	US
Kind code	A1
Filing date	Sep 27, 2021
Priority date	Mar 27, 2019
Publication date	Jan 13, 2022
Grant date	—

Abstract

A distance measuring device includes a control unit and a measuring unit. The control unit controls a photodetector unit. The photodetector unit includes a photoelectric transducer element and an output unit. The photoelectric transducer element generates electrical charges on receiving light reflected from a target as a part of measuring light emitted from a light-emitting unit. The output unit outputs an electrical signal representing a quantity of the electrical charges generated by the photoelectric transducer element. The measuring unit calculates, in accordance with the electrical signal, a distance to the target within a measurable range. The control unit sets, in each of a plurality of intervals that form the measurable range, a conversion ratio of the quantity of the electrical charges generated by the photoelectric transducer element to a quantity of the light received by the photoelectric transducer element.

First claim

1 . A distance measuring device comprising:
a control unit configured to control a photodetector unit, the photodetector unit including a photoelectric transducer element and an output unit, the photoelectric transducer element being configured to generate electrical charges on receiving light reflected from a target as a part of measuring light emitted from a light-emitting unit, the output unit being configured to output an electrical signal representing a quantity of the electrical charges generated by the photoelectric transducer element; and a measuring unit configured to calculate, in accordance with the electrical signal, a distance to the target within a measurable range, the control unit being configured to set, in each of a plurality of intervals that form the measurable range, a conversion ratio of the quantity of the electrical charges generated by the photoelectric transducer element to a quantity of the light received by the photoelectric transducer element.

2 . The distance measuring device of claim 1 , wherein
the photoelectric transducer element is configured to vary the conversion ratio according to a voltage applied thereto, and the control unit is configured to set the conversion ratio by the voltage applied to the photoelectric transducer element in each of the plurality of intervals.

3 . The distance measuring device of claim 2 , wherein
the photoelectric transducer element includes an avalanche photodiode, and the conversion ratio is a multiplication factor of the avalanche photodiode.

4 . The distance measuring device of claim 2 , wherein
the control unit is configured to change the conversion ratio according to a quantity of ambient light.

5 . The distance measuring device of claim 2 , wherein
the control unit is configured to decrease the conversion ratio when a resolution of the distance to the target is to be increased and increase the conversion ratio when the resolution is to be decreased.

6 . The distance measuring device of claim 5 , wherein
the plurality of intervals includes: a first interval; and a second interval corresponding to a longer distance from the photoelectric transducer element than the first interval, and the control unit is configured to decrease the conversion ratio in the first interval and increase the conversion ratio in the second interval.

7 . The distance measuring device of claim 2 , wherein
the control unit is configured to change, in at least one of the plurality of intervals, the conversion ratio according to the quantity of the light that the photoelectric transducer element has received from the target.

8 . The distance measuring device of claim 2 , wherein
the control unit is configured to change the conversion ratio according to an amount of an electric current flowing through the photoelectric transducer element.

9 . The distance measuring device of claim 2 , wherein
the control unit is configured to change the conversion ratio according to length of an exposure duration during which the photoelectric transducer element is allowed to receive the light from the target.

10 . The distance measuring device of claim 1 , wherein
the plurality of intervals includes: a first group including a series of intervals; and a second group including one or more intervals different from the first group, the conversion ratio for the first group is smaller than the conversion ratio for the second group, and the measuring unit is configured to determine, as for the first group, the distance based on a ratio of electrical signals respectively corresponding to multiple adjacent intervals selected from the series of intervals included in the first group.

11 . The distance measuring device of claim 10 , wherein
the measuring unit is configured to determine, as for the second group, the distance by reference to a particular interval corresponding to an electrical signal of the largest magnitude and selected from the one or more intervals included in the second group, and the measuring unit is configured to adopt, as the distance to the target, a longer distance selected from the group consisting of the distance determined with respect to the first group and the distance determined with respect to the second group.

12 . The distance measuring device of claim 1 , wherein
the photodetector unit includes a charge storage device configured to store at least some of the electrical charges generated by the photoelectric transducer element, the control unit is configured to store, in the charge storage device multiple times, the electrical charges generated by the photoelectric transducer element, and the electrical signal has a magnitude corresponding to a quantity of the electrical charges stored in the charge storage device.

13 . A distance measuring system comprising:
the distance measuring device of claim 1 ; the light-emitting unit; and the photodetector unit.

14 . A distance measuring method comprising:
a control step including controlling a photodetector unit, the photodetector unit including a photoelectric transducer element and an output unit, the photoelectric transducer element being configured to generate electrical charges on receiving light reflected from a target as a part of measuring light emitted from a light-emitting unit, the output unit being configured to output an electrical signal representing a quantity of the electrical charges generated by the photoelectric transducer element; and a measuring step including calculating, in accordance with the electrical signal, a distance to the target within a measurable range, the control step including setting, in each of a plurality of intervals that form the measurable range, a conversion ratio of the quantity of the electrical charges generated by the photoelectric transducer element to a quantity of the light received by the photoelectric transducer element.

15 . A non-transitory storage medium that stores thereon a program designed to cause one or more processors to perform the distance measuring method of claim 14 .

16 . The distance measuring device of claim 3 , wherein
the control unit is configured to change the conversion ratio according to a quantity of ambient light.

17 . The distance measuring device of claim 3 , wherein
the control unit is configured to decrease the conversion ratio when a resolution of the distance to the target is to be increased and increase the conversion ratio when the resolution is to be decreased.

18 . The distance measuring device of claim 4 , wherein
the control unit is configured to decrease the conversion ratio when a resolution of the distance to the target is to be increased and increase the conversion ratio when the resolution is to be decreased.

19 . The distance measuring device of claim 17 , wherein
the plurality of intervals includes: a first interval; and a second interval corresponding to a longer distance from the photoelectric transducer element than the first interval, and the control unit is configured to decrease the conversion ratio in the first interval and increase the conversion ratio in the second interval.

20 . The distance measuring device of claim 18 , wherein
the plurality of intervals includes: a first interval; and a second interval corresponding to a longer distance from the photoelectric transducer element than the first interval, and the control unit is configured to decrease the conversion ratio in the first interval and increase the conversion ratio in the second inter

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Koyama Shinzo
• Hirose Yutaka
• Okino Toru
• Saitou Shigeru
• Ishii Motonori
• Odagawa Akihiro

Classifications

• G01S7/4865

  Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487) · CPC title

• G01S17/36

  with phase comparison between the received signal and the contemporaneously transmitted signal · CPC title

• G01S7/4861

  Circuits for detection, sampling, integration or read-out · CPC title

• G01S17/894 Primary

  Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar · CPC title