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US-12625236-B2 - Imaging apparatus and variation information calculation method

US12625236B2US 12625236 B2US12625236 B2US 12625236B2US-12625236-B2

Abstract

An imaging apparatus includes: a light emitter that irradiates a subject with light; and a solid-state imaging device that includes pixel units each of which converts received light into a signal charge, and a signal processor that calculates distance information indicating a distance to the subject. When one or more of the pixel units receive reflected light which is the light irradiated by the light emitter and reflected by the subject, the signal processor (i) calculates the distance information for each of the pixel units by a time-of-flight (TOF) method that uses signal charges, each of the signal charges being the signal charge into which the received light is converted by each of the pixel units, and (ii) calculates, for each of one or more of the pixel units, variation information indicating an amount of variation regarding the distance indicated by the distance information.

Inventors

  • Keiichi Mori
  • Mayu Ogawa

Assignees

  • NUVOTON TECHNOLOGY CORPORATION JAPAN

Dates

Publication Date
20260512
Application Date
20210827

Claims (7)

  1. 1 . A variation information calculation method used by an imaging apparatus including a light emitter that irradiates a subject with pulsed light, and a solid-state imaging device that includes: pixel units each of which converts received light into a signal charge; an exposure controller that controls accumulation of the signal charge performed by each of the pixel units; and a signal processor that calculates distance information indicating a distance to the subject, the variation information calculation method comprising: causing, by the exposure controller, each of the pixel units to accumulate, within one frame, the signal charge at different time phases with respect to a period during which the pulsed light is emitted to generate signals each related to the signal charge which is accumulated at each of the different time phases by each of the pixel units; multiplying, by the signal processor, each of the signals with coefficients, respectively to calculate, by a time-of-flight (TOF) method, the distance information of the subject projected by each of the pixel units, the signals comprising a signal component and a background component, the coefficients varying depending on the distance to the subject and being determined for the signal component and the background component, respectively; calculating, by the signal processor, variation information using each of the signals and the coefficients applied to the signals in the calculation of the distance information, the variation information indicating an amount of variation regarding the distance indicated by the distance information of each of the pixel units; and outputting, by the solid-state imaging device, the distance information and the variation information indicating the amount of variation regarding the distance.
  2. 2 . A variation information calculation method used by an imaging apparatus including a light emitter that irradiates a subject with pulsed light, and a solid-state imaging device that includes: pixel units each of which converts received light into a signal charge; an exposure controller that controls accumulation of the signal charge performed by each of the pixel units; and a signal processor that calculates distance information indicating a distance to the subject, the variation information calculation method comprising: causing, by the exposure controller, each of the pixel units to accumulate, within one frame, the signal charge at different time phases with respect to a period during which the pulsed light is emitted to generate signals each related to the signal charge which is accumulated at each of the different time phases by each of the pixel units; calculating, by the signal processor, using each of the signals and by a time-of-flight (TOF) method, the distance information of the subject projected by each of the pixel units, the signals comprising a signal component and a background component; multiplying, by the signal processor, each of the signals with coefficients, respectively a to calculate light emission component received-light amount information indicating an amount of received light attributed to the pulsed light with which the subject is irradiated by the light emitter, the coefficients varying depending on the distance to the subject and being determined for the signal component and the background component, respectively; calculating, by the signal processor, variation information using each of the signals and the coefficients applied to the signals in the calculation of the light emission component received-light amount information, the variation information indicating an amount of variation regarding the amount of received light indicated by the light emission component received-light amount information of each of the pixel units; and outputting, by the solid-state imaging device, the light emission component received-light amount information and the variation information indicating the amount of variation regarding the amount of received light.
  3. 3 . An imaging apparatus, comprising: a light emitter that irradiates a subject with pulsed light; and a solid-state imaging device that includes: pixel units each of which converts received light into a signal charge; an exposure controller that controls accumulation of the signal charge performed by each of the pixel units; and a signal processor that calculates distance information indicating a distance to the subject, wherein the exposure controller causes each of the pixel units to accumulate, within one frame, the signal charge at different time phases with respect to a period during which the pulsed light is emitted, to generate signals each related to the signal charge which is accumulated at each of the different time phases by each of the pixel units, the signal processor: multiplies the signals with coefficients, respectively, to calculate, by a time-of-flight (TOF) method, the distance information of the subject projected by each of the pixel units, the signals comprising a signal component and a background component, the coefficients varying depending on the distance to the subject and being determined for the signal component and the background component, respectively; and calculates variation information using each of the signals and the coefficients applied to the signals in the calculation of the distance information, the variation information indicating an amount of variation regarding the distance indicated by the distance information of each of the pixel units, and the solid-state imaging device outputs the distance information and the variation information indicating the amount of variation regarding the distance.
  4. 4 . The imaging apparatus according to claim 3 , wherein the signal processor includes a mechanism for switching a set of coefficients in accordance with a magnitude relationship of signal charges, the set of coefficients being used for the calculation of the distance information, at least one of the coefficients being applied to a different one of the signals related to the signal charge, the signal charges being the signal charge accumulated at the different time phases.
  5. 5 . The imaging apparatus according to claim 3 , wherein the one frame includes a first exposure period, a second exposure period, and a third exposure period, the first exposure period synchronizes with time Tp which is a period from a start until an end of irradiation of the pulsed light, the second exposure period is a period from when the irradiation of the pulsed light ends until when time Tp elapses, the third exposure period is a period from when the second exposure period ends until when time Tp elapses, the signal component and the background component are obtained for each of the first, second and third exposure period, and six coefficients are determined for the signal component and the background component for each of the first, second and third exposure period.
  6. 6 . An imaging apparatus, comprising: a light emitter that irradiates a subject with pulsed light; and a solid-state imaging device that includes: pixel units each of which converts received light into a signal charge; an exposure controller that controls accumulation of the signal charge performed by each of the pixel units; and a signal processor that calculates distance information indicating a distance to the subject, wherein: the exposure controller causes each of the pixel units to accumulate, within one frame, the signal charge at different time phases with respect to a period during which the pulsed light is emitted, to generate signals each related to the signal charge which is accumulated at each of the different time phases by each of the pixel units, the signal processor: calculates, using each of the signals and by a time-of-flight (TOF) method, the distance information of the subject projected by each of the pixel units, the signals comprising a signal component and a background component; multiplies the signals with coefficients, respectively, to calculate light emission component received-light amount information indicating an amount of received light attributed to the pulsed light with which the subject is irradiated by the light emitter, the coefficients varying depending on the distance to the subject and being determined for the signal component and the background component, respectively; and calculates variation information using each of the signals and the coefficients applied to the signals in the calculation of the light emission component received-light amount information, the variation information indicating an amount of variation regarding the amount of received light indicated by the light emission component received-light amount information of each of the pixel units, and the solid-state imaging device outputs the light emission component received-light amount information and the variation information indicating the amount of variation regarding the amount of received light.
  7. 7 . The imaging apparatus according to claim 6 , wherein the signal processor includes a mechanism for switching a set of coefficients in accordance with a magnitude relationship of signal charges, the set of coefficients being used for the calculation of the light emission component received-light amount information, at least one of the coefficients being applied to a different one of the signals related to the signal charge, the signal charges being the signal charge accumulated in the different time phases.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This is a continuation application of PCT International Application No. PCT/JP2020/010163 filed on Mar. 10, 2020, designating the United States of America, which is based on and claims priority of U.S. Provisional Patent Application No. 62/826,715 filed on Mar. 29, 2019. The entire disclosures of the above-identified applications, including this specifications, drawings and claims are incorporated herein by reference in their entirety. FIELD The present disclosure relates to imaging apparatuses that obtain distance information of a subject. BACKGROUND Imaging apparatuses that perform distance measurement using a time-of-flight (TOF) method and calculate distance information indicating the distance to a subject are conventionally known (for example, see PTL 1). CITATION LIST Patent Literature PTL 1: Japanese Unexamined Patent Application Publication No. 2018-136123 SUMMARY Technical Problem Processes performed using a distance indicated by distance information to be calculated include a process that enables obtaining more appropriate results if the reliability of the distance can be determined (e.g., a filtering process performed on a distance map). In view of this, the present disclosure provides an imaging apparatus, etc. capable of determining the reliability of the distance indicated by distance information to be calculated. Solution to Problem An imaging apparatus according to an aspect of the present disclosure includes: a light emitter that irradiates a subject with light; and a solid-state imaging device that includes pixel units each of which converts received light into a signal charge, and a signal processor that calculates distance information indicating a distance to the subject. When one or more of the pixel units receive reflected light which is the light irradiated by the light emitter and reflected by the subject, the signal processor (i) calculates the distance information for each of the pixel units by a time-of-flight (TOF) method that uses signal charges, each of the signal charges being the signal charge into which the received light is converted by each of the pixel units, and (ii) calculates variation information for each of one or more of the pixel units, the variation information indicating an amount of variation regarding the distance indicated by the distance information. A variation information calculation method according to an aspect of the present disclosure is used by an imaging apparatus that includes: a light emitter that irradiates a subject with light; and a solid-state imaging device that includes pixel units each of which converts received light into a signal charge, and a signal processor that calculates distance information indicating a distance to the subject. The variation information calculation method includes: when one or more of the pixel units receive reflected light which is the light irradiated by the light emitter and reflected by the subject, (i) calculating, by the signal processor, the distance information for each of the pixel units by a TOF method that uses signal charges, each of the signal charges being the signal charge into which the received light is converted by each of the pixel units, and (ii) calculating, by the signal processor, variation information for each of one or more of the pixel units, the variation information indicating an amount of variation regarding the distance information. Advantageous Effects Provided is an imaging apparatus, etc. capable of determining the reliability of the distance indicated by distance information to be calculated. BRIEF DESCRIPTION OF DRAWINGS These and other advantages and features will become apparent from the following description thereof taken in conjunction with the accompanying Drawings, by way of non-limiting examples of embodiments disclosed herein. FIG. 1 is a block diagram illustrating an example of a configuration of an imaging apparatus according to Embodiment 1. FIG. 2 is a block diagram illustrating an example of a configuration of a signal processor according to Embodiment 1. FIG. 3 is a block diagram illustrating an example of a configuration of an imager according to Embodiment 1. FIG. 4 is a block diagram illustrating an example of a configuration of a pixel unit according to Embodiment 1. FIG. 5 is a timing chart regarding a first exposure sequence according to Embodiment 1. FIG. 6 is another timing chart regarding the first exposure sequence according to Embodiment 1. FIG. 7 is a timing chart regarding a second exposure sequence according to Embodiment 1. FIG. 8 is a block diagram illustrating an example of a configuration of an imaging apparatus according to Embodiment 2. FIG. 9 is a block diagram illustrating an example of a configuration of a signal processor according to Embodiment 2. DESCRIPTION OF EMBODIMENTS An imaging apparatus according to an aspect of the present disclosure includes: a light emitter that irradiates a subject with light;