Imaging apparatus including light source, photodetector, and control circuit

• US 10,257,397 B2
• Filed: 03/15/2017
• Issued: 04/09/2019
• Est. Priority Date: 03/31/2016
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Ando, Takamasa
• Primary Examiner(s): Kumar, Pankaj
• Assistant Examiner(s): Newlin, Timothy R
• Application Number:
  US15/459,029
• Publication Number:
  US 20170289469A1
• Time in Patent Office: 755 Days
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7235 Details of waveform analysis A61B5/349 takes precedence
• CPC Class Codes: G01S 17/18 wherein range gates are used
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G03G 15/04 for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
• CPC Class Codes: H04N 23/56 provided with illuminating means

Abstract

An imaging apparatus includes a light source that includes a diffusion plate and, in operation, emits, toward a subject, pulsed light that diverges; a photodetector that includes a photoelectric converter that, in operation, receives light from the subject and converts the light to an electric charge and an electric charge accumulator that, in operation, accumulates the electric charge, and, in operation, generates an electric signal based on the accumulated electric charge; and a control circuit that, in operation, controls the light source and the photodetector. The control circuit, in operation, causes the electric charge accumulator to start accumulating the electric charge when a period of time has passed after the control circuit has caused the light source to start emitting the pulsed light, and causes the electric charge accumulator to accumulate the electric charge corresponding to a component, among the light from the subject, that is scattered inside the subject.

Claims

1. An imaging apparatus, comprising:

a light source that includes a diffusion plate and, in operation, emits pulsed light toward a subject, the pulsed light diverging at a divergence angle greater than 0 degrees;

a photodetector including a photoelectric converter that, in operation, receives light from the subject and converts the light to an electric charge, and an electric charge accumulator that, in operation, accumulates the electric charge, the photodetector, in operation, generating an electric signal based on the electric charge accumulated in the electric charge accumulator; and

a control circuit that, in operation, controls the light source and the photodetector, wherein;

the control circuit, in operation, causes the electric charge accumulator to start accumulating the electric charge when a predetermined period of time has passed after the control circuit has caused the light source to start emitting the pulsed light, and thus causes the electric charge accumulator to accumulate the electric charge corresponding to a component, among the light from the subject, that is scattered inside the subject, and

the pulsed light satisfies the following expression;

81.5≤

R+d/(2 tan θ

), where R (mm) is a distance from the diffusion plate to the subject, θ

(degree) is the divergence angle, and d (mm) is a spot size of the pulsed light on the diffusion plate.

2. The imaging apparatus according to claim 1, further comprising:

a divergence angle adjusting mechanism that, in operation, adjusts the divergence angle.

3. The imaging apparatus according to claim 1, further comprising:

a pattern projector that, in operation, converts the pulsed light to light including a desired pattern.

4. The imaging apparatus according to claim 1, wherein:

the electric signal includes a predetermined offset component, and

the control circuit, in operation, removes the predetermined offset component from the electric signal.

5. The imaging apparatus according to claim 1, wherein the distance from the diffusion plate to the subject is equal to or greater than 25 mm, and is equal to or less than 400 mm.