Imaging system

Patent metadata

Field	Value
Publication number	US-2018217258-A1
Application number	US-201715840468-A
Country	US
Kind code	A1
Filing date	Dec 13, 2017
Priority date	Jan 31, 2017
Publication date	Aug 2, 2018
Grant date	—

Abstract

An imaging system includes a light-emitting device, an image sensor, and a control circuit. The light-emitting device includes a light source, a first waveguide that propagates light from the light source by means of total reflection, a second waveguide, and a first adjustment element. The control circuit causes the light source to repeatedly emit light pulses. Further, the control circuit causes at least some of the plurality of photo-detection cells to accumulate the signal charge in synchronization with the emission of the light pulses and thereby causes the image sensor to generate every first period of time a frame based on the signal charge thus accumulated. Furthermore, the control circuit causes the first adjustment element to change the direction of the emitted light from the second waveguide every second period of time that is shorter than or equal to half the first period of time.

First claim

What is claimed is:

1 . An imaging system comprising:
a light-emitting device; an image sensor; and a control circuit that controls the light-emitting device and the image sensor, wherein the light-emitting device includes:
a light source;
a first waveguide that propagates light from the light source by means of total reflection;
a second waveguide; and
a first adjustment element,
the second waveguide includes:
a first multilayer reflective film;
a second multilayer reflective film facing the first multilayer reflective film; and
a first optical guiding layer joined directly to the first waveguide and located between the first multilayer reflective film and the second multilayer reflective film,
the first optical guiding layer has a variable thickness and/or a variable refractive index with respect to the light and propagates the light having propagated through the first waveguide, the first multilayer reflective film has a higher light transmittance than the second multilayer reflective film and causes a portion of the light propagating through the first optical guiding layer to be emitted as emitted light toward outside the second waveguide, the first adjustment element changes a direction of the emitted light from the second waveguide by changing the thickness of the first optical guiding layer and/or the refractive index of the first optical guiding layer, the image sensor includes a plurality of photo-detection cells that receive reflected light from a physical object reflecting at least a portion of the emitted light from the second waveguide, each of the photo-detection cells accumulates signal charge corresponding to an amount of light received, and the control circuit
causes the light source to repeatedly θ out light pulses as the light,
causes at least some of the plurality of photo-detection cells to accumulate the signal charge in synchronization with the emission of the light pulses by the light source and thereby causes the image sensor to generate every first period of time a frame based on the signal charge thus accumulated, and
causes the first adjustment element to change the direction of the emitted light from the second waveguide every second period of time that is shorter than or equal to half the first period of time.

2 . An imaging system comprising:
a light-emitting device; an image sensor; and a control circuit that controls the light-emitting device and the image sensor, wherein the light-emitting device includes:
a light source;
a first waveguide that propagates light from the light source by means of total reflection;
a second waveguide;
a third waveguide; and
a first adjustment element,
the second waveguide includes:
a first multilayer reflective film;
a second multilayer reflective film facing the first multilayer reflective film; and
a first optical guiding layer located between the first multilayer reflective film and the second multilayer reflective film,
the third waveguide includes:
a third multilayer reflective film;
a fourth multilayer reflective film facing the third multilayer reflective film; and
a second optical guiding layer located between the third multilayer reflective film and the fourth multilayer reflective film,
the second optical guiding layer is joined directly to the first waveguide and propagates the light having propagated through the first waveguide, the first optical guiding layer is joined directly to the second optical guiding layer, has a variable thickness and/or a variable refractive index with respect to the light, and propagates the light having propagated through the second optical guiding layer, the first multilayer reflective film has a higher light transmittance than the second multilayer reflective film and causes a portion of the light propagating through the first optical guiding layer to be emitted as emitted light toward outside the second waveguide, the first adjustment element changes a direction of the emitted light from the second waveguide by changing the thickness of the first optical guiding layer and/or the refractive index of the first optical guiding layer, the image sensor includes a plurality of photo-detection cells that receive reflected light from a physical object reflecting at least a portion of the emitted light from the second waveguide, each of the photo-detection cells accumulates signal charge corresponding to an amount of light received, and the control circuit
causes the light source to repeatedly θ out light pulses as the light,
causes at least some of the plurality of photo-detection cells to accumulate the signal charge in synchronization with the emission of the light pulses by the light source and thereby causes the image sensor to generate every first period of time a frame based on the signal charge thus accumulated, and
causes the first adjustment element to change the direction of the emitted light from the second waveguide every second period of time that is shorter than or equal to half the first period of time.

3 . The imaging system according to claim 1 , wherein the first period of time is n times (where n is an integer or 2 or larger) as long as the second period of time.

4 . The imaging system according to claim 1 , wherein the control circuit scans an object region by causing the first adjustment element to change the direction of the emitted light from the second waveguide every second period of time, and
a period of time required to scan the whole object region is equal to or longer than the first period of time.

5 . The imaging system according to claim 4 , wherein the period of time required to scan the whole object region is m time(s) (where m is an integer of 1 or larger) as long as the first period of time.

6 . The imaging system according to claim 1 , wherein the control circuit allows only at least one of the photo-detection cells to accumulate the signal charge and does not allow the remaining photo-detection cells to accumulate the signal charge.

7 . The imaging system according to claim 1 , wherein the control circuit allows some of the plurality of photo-detection cells that are chosen according to a position and size of a light spot that is formed by the light-emitting device to accumulate the signal charge and does not allow the remaining photo-detection cells to accumulate the signal charge.

8 . The imaging system according to claim 1 , wherein the plurality of photo-detection cells are arrayed in a row-wise direction and a column-wise direction,
the light-emitting device forms, within an object region, a light spot extending in a direction corresponding to the row-wise direction or the column-wise direction, and the control circuit moves the light spot every second period of time in a direction perpendicular to the direction in which the light spot extends, and causes the plurality of photo-detection cells to accumulate the signal charge row by row or column by column.

9 . The imaging system according to claim 1 , further comprising a plurality of one-dimensionally or two-dimensionally arrayed image sensors including the image sensor,
wherein the control circuit causes the first adjustment element to change the direction of the emitted light from the second waveguide and thereby causes the reflected light to fall on the plurality of image sensors in sequence so that the plurality of image sensors generate frames in sequence.

10 . The imaging system according to claim 1 , wherein the emitted light includes a zeroth-order diffracted beam and positive and negative first-order diffracted beams, and
the control circuit allows only some of the plurality of photo-detection cells that receive a

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Hirasawa Taku
• Inada Yasuhisa
• Hashiya Akira

Classifications

• H04N23/60

  Control of cameras or camera modules · CPC title

• H04N23/71 Primary

  Circuitry for evaluating the brightness variation · CPC title

• G02F1/2955 Primary

  by controlled diffraction or phased-array beam steering (controlled diffraction for optical waveguide switching G02F1/313) · CPC title

• G01S17/86 Primary

  Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders · CPC title

• G01S17/10

  using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) · CPC title