BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a flexible tube insertion device having a flexible tube section to be inserted into an insertion target, an insertion control device, and an insertion method.

2. Description of the Related Art

In order to improve the insertability of the insertion section (flexible tube section) of a flexible tube insertion device such as an endoscope apparatus, the technique of varying the bending stiffness of part of the insertion section is widely known.

For example, Jpn. Pat. Appln. KOKAI Publication No. 2006-218232 discloses an endoscope apparatus having an insertion section, which includes a bendable section, a first flexible tube section, and a second flexible tube section, in this order from the distal end. The first flexible tube section constitutes a passively bendable section that is passively bent under a predetermined amount of force received from a flexure of an insertion target when the first flexible tube section is inserted into the insertion target and passes through the flexure. In such an endoscope apparatus, since the passively bendable section is bent when passing through the flexure, only light load is applied to the flexure, enhancing the insertability.

Jpn. Pat. Appln. KOKAI Publication No. 2016-7434 discloses an endoscope apparatus in which the insertion section is divided into segments in the longitudinal direction, the shape of each segment is detected, and the bending stiffness of each segment is varied according to the detected bent shape, so that the insertability is improved.

BRIEF SUMMARY OF THE INVENTION

An aspect of the present invention is directed to a flexible tube insertion device. The flexible tube insertion device includes a flexible tube section segmented along an axial direction into segments and configured to be inserted into an insertion target, at least one variable stiffness unit configured to vary bending stiffness of the flexible tube section in units of at least one segment, at least one state detector configured to detect information relating to shape information of the flexible tube section and a stiffness controller configured to cause the at least one variable stiffness unit to reduce bending stiffness of a portion of the flexible tube section including a place where the flexible tube section is easy to bend in units of at least one segment based on the shape information.

Another aspect of the present invention is directed to an insertion control device of a flexible tube section. The flexible tube section is segmented along an axial direction into segments and configured to be inserted into an insertion target. The insertion control device includes a base point determination section configured to detect a place where the flexible tube section is easy to bend to determine the place as a base point of varying bending stiffness of the flexible tube section, based on shape information obtained by at least one state detector configured to detect the shape information of the flexible tube section, and a stiffness controller configured to cause at least one variable stiffness unit to vary the bending stiffness of a portion of the flexible tube section including the place where the flexible tube section is easy to bend in units of at least one segment.

Still another aspect of the present invention is directed to an insertion method of a flexible tube section into an examination target. The flexible tube section is segmented along an axial direction into segments. The method includes inserting the flexible tube section into the examination target, and controlling stiffness of the flexible tube section so that the stiffness of a segment including a place where the flexible tube section is easy to bend is reduced.

Advantages of the invention will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

