CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C § 119(a) to Japanese Patent Application No. 2018-127445 filed on Jul. 4, 2018. The above application is hereby expressly incorporated by reference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an endoscope apparatus that measures the size of a subject.

2. Description of the Related Art

A distance to an object to be observed, the size of an object to be observed, or the like is acquired in an endoscope apparatus. For example, in JP1991-231622A (JP-H03-231622A), a beam is applied to a subject from the distal end portion of an endoscope and a distance to an object to be observed and the like are calculated from the position and angle of a point of the beam that is formed on the subject by the application of the beam. Further, in JP2017-508529A (corresponding to US2016/287141A1), planar light is applied to a subject to form an intersection curve where the planar light and the subject cross each other on the subject and a distance between two points on the intersection curve is calculated. Furthermore, in JP2013-005830A, in a case where two illumination windows emitting illumination light are provided at the distal end portion of an endoscope, two bright spots are formed on a subject by two pieces of illumination light emitted from these two illumination windows and a distance to an object to be observed is calculated from a distance between the two bright spots.

SUMMARY OF THE INVENTION

Since subjects to be observed by an endoscope in a medical field often have a three-dimensional shape, there is a need for a method of acquiring measurement information suitable for a three-dimensional shape. In this regard, since only positional information about one point based on a beam is obtained in the JP1991-231622A (JP-H03-231622A), a method disclosed in JP1991-231622A (JP-H03-231622A) is not suitable for the acquisition of measurement information in a case where a subject has a three-dimensional shape.

On the other hand, since a distance is calculated from two points on the intersection curve in JP2017-508529A, a method disclosed in JP2017-508529A is suitable for the acquisition of measurement information in a case where a subject has a three-dimensional shape. However, since a user needs to designate two points on the intersection curve by a graphical user interface (GUI), the method disclosed in JP2017-508529A is inconvenient in the operation of an endoscope where a user uses both hands. Further, since the intersection curve is always changed, the intersection curve is designated in a static image in JP2017-508529A. For this reason, there is a need for a method for measuring a distance between two points not in a static image but in a motion picture.

Further, in JP2013-005830A, measurement information in a case where a subject has a three-dimensional shape can be more accurately acquired using positional information about a portion between two bright spots. However, since only positional information about two bright spots is obtained in the case of JP2013-005830A, it is difficult to grasp information about a portion between these two bright spots, for example, the undulation of a subject and the like.

An object of the invention is to provide an endoscope apparatus that can simply and accurately obtain measurement information without imposing a burden on a user in a case where a subject has a three-dimensional shape.

An endoscope apparatus according to an aspect of the invention comprises an auxiliary measurement light-emitting unit that emits auxiliary measurement light as planar light including at least two first feature lines, an imaging element that images a subject illuminated with the auxiliary measurement light, an image acquisition unit that acquires a taken image obtained in a case where the subject is imaged by the imaging element, the taken image including an intersection curve formed on the subject and at least two first feature points formed at positions corresponding to the first feature lines on the intersection curve, a position specifying unit that specifies at least positions of the first feature points on the basis of the taken image, and a display control unit that displays measurement information representing an actual size of the subject in the taken image by using the positions of the first feature points.

It is preferable that the measurement information includes a first straight-line distance between the two first feature points. It is preferable that the measurement information includes a second straight-line distance between one of the two first feature points and a specific point other than the two first feature points. It is preferable that the measurement information includes a length of a specific intersection curved portion of the intersection curve positioned between the two first feature points, the position specifying unit specifies a position of the specific intersection curved portion, and the display control unit displays the length of the specific intersection curved portion in the taken image by using the positions of the first feature points and the position of the specific intersection curved portion.

It is preferable that the auxiliary measurement light includes a plurality of second feature lines, which are different from the first feature lines, between the two first feature lines, the specific intersection curved portion includes a plurality of second feature points formed on the intersection curve by the second feature lines so as to be smaller than the first feature points, and the position specifying unit specifies the position of the specific intersection curved portion from the plurality of second feature points included in the taken image.

It is preferable that the endoscope apparatus further comprises a measurement information switching unit that switches the measurement information to be displayed in the taken image to any one of a plurality of pieces of measurement information or a combination of two or more of a plurality of pieces of measurement information in a case where there are a plurality of pieces of measurement information. It is preferable that the endoscope apparatus further comprises a static image-acquisition command unit giving a static image-acquisition command to acquire a static image of the taken image and the measurement information is also stored together in a case where the static image-acquisition command is given.

It is preferable that the endoscope apparatus further comprises a first light source unit emitting illumination light for illuminating the subject and the auxiliary measurement light-emitting unit includes a second light source unit provided independently of the first light source unit and an auxiliary measurement optical element used to obtain the auxiliary measurement light from light emitted from the second light source unit. It is preferable that the auxiliary measurement light-emitting unit includes a specific optical member used to emit the auxiliary measurement light toward the subject in a state where an optical axis of the imaging element and an optical axis of the auxiliary measurement light cross each other. It is preferable that the specific optical member is provided with an anti-reflection portion. It is preferable that the auxiliary measurement light-emitting unit includes an auxiliary measurement slit used to emit the auxiliary measurement light toward the subject in a state where an optical axis of the imaging element and an optical axis of the auxiliary measurement light cross each other. It is preferable that the second light source unit is a laser light source. It is preferable that a wavelength of light emitted from the second light source unit is in the range of 495 nm to 570 nm.

According to the aspect of the invention, it is possible to simply and accurately obtain measurement information without imposing a burden on a user in a case where a subject has a three-dimensional shape.

