Endoscope

1. An endoscope having a bending portion close to a distal end of an insertion section, comprising:

bending means for bending said bending portion;

manipulating means for performing bending operations of said bending portion;

drive means for bending said bending portion with said bending means;

bend amount detecting means for detecting a bend amount of said bending portion;

brake instructing means for giving a brake instruction to keep said bending portion in a bent state;

brake release means for giving a brake release instruction to discontinue maintenance of the bent state; and

control means for controlling drive of said drive means,

wherein, in response to the brake instruction given by said brake instructing means, said control means acquires the bend amount of said bending portion upon the brake instruction being given from said bend amount detecting means to drive said drive means so as to maintain the bend amount and, when the brake release instruction is given by said brake release means while the bent state is being maintained, gradually reduces a drive force of said drive means.

2. The endoscope according to claim 1 , further comprising:

manipulating force detecting means for detecting a manipulating force applied to said manipulating means,

wherein said control means assists said bending means in bending said bending portion through said drive means with a force applied with a given ratio to the manipulating force according to the manipulating force detected by said manipulating force detecting means.

3. The endoscope according to claim 2 , wherein, when the brake instruction is given by said brake instructing means, said control means gradually reduces an assist drive force of said drive means corresponding to an assist in the bending to 0, and gradually increases a maintenance drive force of said drive means corresponding to the maintenance of the bend amount to maintain the bend amount.

4. The endoscope according to claim 2 , wherein, upon the brake instruction being given by said brake instructing means, said control means reduces the assist drive force of said drive means corresponding to the assist in the bending to 0.

5. The endoscope according to claim 2 ,

wherein said control means is provided with

a first control mode for gradually reducing to “0” the assist drive force of said drive means corresponding to the assist in the bending in response to the brake instruction by said brake instructing means while gradually increasing the maintenance drive force of said drive means corresponding to the maintenance of the bend amount to maintain the bend amount, and

a second control mode for reducing to 0 the assist drive force of said drive means corresponding to the assist in the bending upon the brake instruction being given by said brake instructing means,

wherein said endoscope further comprises:

first selecting means for selecting one of the first control mode and the second control mode, and

wherein said control means controls drive of said drive means according to a control mode selected by said first selecting means.

6. The endoscope according to claim 2 , wherein when the brake release instruction is given, said control means gradually increases the assist drive force of said drive means corresponding to the assist in the bending to produce a force with a given ratio to the manipulating force.

7. The endoscope according to claim 2 , wherein, upon the manipulating force being detected by said manipulating force detecting means after the brake release instruction is given, said control means reduces to 0 the maintenance drive force for said drive means corresponding to the maintenance of the bend amount.

8. The endoscope according to claim 2 , wherein said control means is provided with

a third control mode for gradually increasing the assist drive force of said drive means corresponding to the bending assist in response to the brake release instruction to produce a force with a given ratio to the manipulating force, and

a fourth control mode for reducing to 0 the maintenance drive force of said drive means corresponding to the maintenance of the bend amount upon the manipulating force being detected by said manipulating force detecting means after the brake release instruction is given,

wherein the endoscope further comprises:

second selecting means for selecting one of the third control mode and the fourth control mode, and

wherein said control means controls drive of said drive means according to a control mode selected by said second selecting means.

9. The endoscope according to claim 1 , wherein said bending means is provided to bend said bending portion by withdrawing a wire inserted into said bending portion, and wherein said bend amount detecting means detects the bend amount of said bending portion by detecting an angle of rotation of a pulley over which said wire is passed.

10. The endoscope according to claim 1 , wherein said bending means is provided to bend said bending portion by withdrawing a wire inserted into said bending portion, and wherein said bend amount detecting means detects the bend amount of said bending portion by detecting a displacement of said wire.

11. The endoscope according to claim 1 , wherein said bend amount detecting means detects the bend amount of said bending portion by detecting an angle of rotation of a gear engaged with said drive means.

12. The endoscope according to claim 1 , wherein said bend amount detecting means detects the bend amount of said bending portion by detecting a bending angle of said bending portion.