Transmission mechanism, raising device, and insertion apparatus

1. A transmission mechanism configured to be coupled to each of a raising stand that raises and a raising operation portion to operate a raise of the raising stand and to transmit an operational force of the raising operation portion to the raising stand, the transmission mechanism comprising:

a movable member which moves forward and backward along an axial direction of the transmission mechanism by an operation of the raising operation portion;

an adjustment unit which is coupled to the movable member and moves forward and backward along the axial direction together with the movable member and which comprises an expansion and contraction member that changes in length in the axial direction;

an elongated member coupled to the raising stand and the adjustment unit in a state where tension adjusted by the change of the length of the expansion and contraction member is acting thereon and which pulls or presses the raising stand;

a regulation surface portion which contacts the adjustment unit; and

a support portion which is provided in contact with the movable member and which moves the regulation surface portion forward and backward together with the movable member to support the regulation surface portion at a position to regulate the change of the length of the expansion and contraction member when the raising operation portion is operated and when tension is applied to the adjustment unit and the length of the expansion and contraction member changes.

2. The transmission mechanism according to claim 1 , wherein the regulation surface portion and the support portion are configured to regulate the change of the length of the expansion and contraction member for the adjustment unit in which the raising stand is in a raised state and in which the length of the expansion and contraction member will exceed a maximum permissible expansion amount, and keep the tension acting on the elongated member in the raised state of the raising stand.

3. The transmission mechanism according to claim 1 , wherein the regulation surface portion and the support portion are continuous with each other, and

the support portion is removably fixed to the movable member.

4. The transmission mechanism according to claim 3 , wherein the adjustment unit comprises a coupling member which is coupled to the expansion and contraction member and the elongated member and which moves forward and backward along the axial direction together with the movable member and the expansion and contraction member, and

the transmission mechanism further comprises a guide member which guides the movable member and the coupling member along the axial direction.

5. The transmission mechanism according to claim 4 , wherein the support portion surrounds the movable member, the expansion and contraction member, and the coupling member as one unit, and

the support portion has such a length that a back surface of the support portion contacts a back surface of the movable member when the regulation surface portion contacts the coupling member.

6. The transmission mechanism according to claim 5 , wherein when the movable member moves backward by the operation of the raising operation portion, the movable member pulls the support portion backward in a state where the back surface of the movable member is in contact with the back surface of the support portion, so that the support portion including the regulation surface portion moves backward together with the movable member, and

when the movable member moves forward by the operation of the raising operation portion, the coupling member presses the support portion forward in a state where a front surface of the coupling member is in contact with the regulation surface portion which functions as a front surface of the support portion, so that the support portion including the regulation surface portion moves forward together with the movable member.

7. The transmission mechanism according to claim 6 , wherein the guide member is configured to guide the movable member and the coupling member along the axial direction via the support portion.

8. The transmission mechanism according to claim 7 , wherein the guide member comprises a slit portion into which side surfaces of the support portion are inserted.

9. The transmission mechanism according to claim 6 , wherein the support portion comprises

an upper surface portion which functions as a flat-plate-shaped frame provided along the axial direction and which covers the upper parts of the movable member, the expansion and contraction member, and the coupling member,

a pair of extension portions which are continuous with a proximal end portion of the upper surface portion and which extend along a direction that intersects at right angles with the axial direction and which catch the movable member therebetween, and

claw portions which are provided at a distal end portions of the extension portions and which are caught on a catching portion provided on a bottom surface side of the movable member.

10. The transmission mechanism according to claim 9 , wherein the adjustment unit comprises

a coupling member which is coupled to the expansion and contraction member and the elongated member and which moves forward and backward along the axial direction together with the movable member and the expansion and contraction member, and

the regulation surface portion is provided between the raising stand and the coupling member in an expansion and contraction direction of the expansion and contraction member.

11. The transmission mechanism according to claim 10 , wherein when the expansion and contraction member expands to a predetermined permissible expansion amount, the regulation surface portion prevents the expansion and contraction member from expanding more than the predetermined permissible expansion amount by the contact of the regulation surface portion with the coupling member which moves toward the raising stand due to the expansion of the expansion and contraction member.

12. The transmission mechanism according to claim 9 , wherein the support portion has such a length that the extension portions contact a protruding portion of the movable member when the regulation surface portion contacts the coupling member.

13. The transmission mechanism according to claim 9 , wherein when the movable member moves backward by the operation of the raising operation portion, the movable member pulls the support portion backward so that a protruding portion of the movable member contacts the extension portions, and the support portion including the regulation surface portion moves backward together with the movable member due to the contact, and

when the movable member moves forward by the operation of the raising operation portion, the coupling member presses the support portion forward in a state where the front surface of the coupling member is in contact with the regulation surface portion which functions as a front surface of the support portion, so that the support portion including the regulation surface portion moves forward together with the movable member due to the pressing.

14. A raising device comprising:

the raising stand;

the raising operation portion; and

the transmission mechanism according to claim 1 .

15. An insertion apparatus comprising:

an insertion portion;

a holding portion provided at a proximal end portion of the insertion portion; and

the raising device according to claim 14 ;

wherein the raising stand is provided inside a distal end portion of the insertion portion;

the raising operation portion is provided at the holding portion; and

the transmission mechanism is provided inside the holding portion and inside the insertion portion.