Imaging apparatus including light source that emits pulsed light, image sensor, and control circuit

Patent metadata

Field	Value
Publication number	US-2016373652-A1
Application number	US-201615176165-A
Country	US
Kind code	A1
Filing date	Jun 8, 2016
Priority date	Jun 17, 2015
Publication date	Dec 22, 2016
Grant date	—

Abstract

An imaging apparatus according to an aspect of the present disclosure includes a light source that, in operation, emits first pulsed light and second pulsed light, an image sensor that includes at least one pixel including a photodiode, a first charge accumulator and a second charge accumulator, the first charge accumulator and the second charge accumulator, in operation, accumulating signal charge from the photodiode, and a control circuit that, in operation, controls the image sensor. The control circuit, in operation, causes the first charge accumulator to begin to accumulate the signal charge a period of time after the light source begins to emit the first pulsed light. The control circuit, in operation, causes the second charge accumulator to begin to accumulate the signal charge the period of time after the light source begins to emit the second pulsed light.

First claim

What is claimed is:

1 . An imaging apparatus comprising:
a light source that, in operation, emits first pulsed light and second pulsed light; an image sensor that includes at least one pixel including a photodiode, a first charge accumulator and a second charge accumulator, the first charge accumulator and the second charge accumulator, in operation, accumulating signal charge from the photodiode; and a control circuit that, in operation, controls the image sensor, wherein: the control circuit, in operation, causes the first charge accumulator to begin to accumulate the signal charge a period of time after the light source begins to emit the first pulsed light; and the control circuit, in operation, causes the second charge accumulator to begin to accumulate the signal charge the period of time after the light source begins to emit the second pulsed light.

2 . The imaging apparatus according to claim 1 , wherein:
the image sensor further includes an electronic shutter; the control circuit, in operation, causes the electronic shutter to prevent the first charge accumulator from accumulating the signal charge while a part of the first pulsed light is reflected from a surface of a measurement target and reaches the image sensor; the control circuit, in operation, causes the electronic shutter to allow the first charge accumulator to accumulate the signal charge while another part of the first pulsed light is scattered inside the measurement target and reaches the image sensor; the control circuit, in operation, causes the electronic shutter to prevent the second charge accumulator from accumulating the signal charge while a part of the second pulsed light is reflected from the surface of the measurement target and reaches the image sensor; and the control circuit, in operation, causes the electronic shutter to allow the second charge accumulator to accumulate the signal charge while another part of the second pulsed light is scattered inside the measurement target and reaches the image sensor.

3 . The imaging apparatus according to claim 1 ,
wherein the at least one pixel comprises pixels arranged in two dimensions.

4 . The imaging apparatus according to claim 2 , wherein:
the control circuit, in operation, causes the electronic shutter to allow the first charge accumulator to begin to accumulate the signal charge when a trailing edge of the first pulsed light is reflected from the surface of the measurement target and reaches the image sensor or later; and the control circuit, in operation, causes the electronic shutter to allow the second charge accumulator to begin to accumulate the signal charge when a trailing edge of the second pulsed light is reflected from the surface of the measurement target and reaches the image sensor or later.

5 . The imaging apparatus according to claim 1 ,
wherein the control circuit, in operation, determines the period of time on the basis of intensity of the signal charge accumulated in the first charge accumulator and the second charge accumulator.

6 . The imaging apparatus according to claim 1 ,
wherein the control circuit, in operation, calculates a distance between the image sensor and the measurement target and determines the period of time on the basis of the distance.

7 . The imaging apparatus according to claim 1 , wherein:
the control circuit, in operation, causes the first charge accumulator to accumulate the signal charge at a plurality of times when a trailing edge of the first pulsed light is reflected from a surface of a measurement target and reaches the image sensor or later; the control circuit, in operation, obtains a first optical length distribution of a component of the first pulsed light scattered inside the measurement target on the basis of a change in intensity of the signal charge accumulated at the plurality of times by the first charge accumulator; the control circuit, in operation, causes the second charge accumulator to accumulate the signal charge at the plurality of times when a trailing edge of the second pulsed light is reflected from the surface of the measurement target and reaches the image sensor or later; and the control circuit, in operation, obtains a second optical length distribution of a component of the second pulsed light scattered inside the measurement target on the basis of a change in intensity of the signal charge accumulated at the plurality of times by the second charge accumulator.

8 . The imaging apparatus according to claim 1 , further comprising:
a correction circuit that, in operation, corrects movement of a measurement target.

9 . The imaging apparatus according to claim 8 ,
wherein the correction circuit, in operation, corrects the movement of the measurement target by detecting periodic vibration of the measurement target.

10 . The imaging apparatus according to claim 1 , wherein:
the first pulsed light includes a third light; the second pulsed light includes a fourth light; and the fourth light has a wavelength different from a wavelength of the third pulsed light.

11 . The imaging apparatus according to claim 1 ,
wherein the second pulsed light has a polarization characteristic different from a polarization characteristic of the first pulsed light.

12 . An imaging apparatus comprising:
a first light source that, in operation, emits first pulsed light; a second light source that, in operation, emits second pulsed light; an image sensor that includes at least one pixel including a photodiode, a first charge accumulator and a second charge accumulator, the first charge accumulator and the second charge accumulator, in operation, accumulating signal charge from the photodiode; and a control circuit that, in operation, controls the image sensor, wherein: the control circuit, in operation, causes the first charge accumulator to begin to accumulate the signal charge a period of time after the light source begins to emit the first pulsed light; and the control circuit, in operation, causes the second charge accumulator to begin to accumulate the signal charge the period of time after the light source begins to emit the second pulsed light.

13 . The imaging apparatus according to claim 12 , wherein:
the first pulsed light includes a third light; the second pulsed light includes a fourth light; and the fourth light has a wavelength different from a wavelength of the third pulsed light.

14 . The imaging apparatus according to claim 12 ,
wherein the second pulsed light has a polarization characteristic different from a polarization characteristic of the first pulsed light.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Ando Takamasa
• Korenaga Tsuguhiro
• Fujii Toshiya

Classifications

• A61B5/1455 Primary

  using optical sensors, e.g. spectral photometrical oximeters · CPC title

• H04N23/73

  by influencing the exposure time · CPC title

• H04N23/71 Primary

  Circuitry for evaluating the brightness variation · CPC title

• H04N25/53

  Control of the integration time · CPC title

• H04N23/745

  Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination · CPC title