Endoscope having chain locking prevention function

An endoscope having chain locking prevention function, the endoscope comprising:

• an insertion part having a lighting photographing part on a front end thereof;
• an operation part having an upper chain and a lower chain wound around an upper sprocket and a lower sprocket of a rotary shaft for operating the front end of the insertion part to be bent;
• and
• a direction conversion module for converting rotational motions of the upper sprocket and the lower sprocket to linear motions of the upper chain and the lower chain,
• wherein the direction conversion module comprises:
• a lower finishing plate;
• a first connection block and a second connection block for connecting both ends of the upper chain to a first connection wire and a second connection wire of the operation part;
• a third connection block and a fourth connection block for connecting both ends of the lower chain to a third connection wire and a fourth connection wire of the operation part;
• a first guide rail having a predetermined length and disposed between the first connection block and the third connection block to guide slide movements of the first connection block and the third connection block, wherein the first guide rail is fixed to the lower finishing plate;
• a second guide rail having a predetermined length and disposed between the second connection block and the fourth connection block to guide slide movements of the second connection block and the fourth connection block, wherein the second guide rail is fixed to the lower finishing plate;
• a chain cover having a rounded surface for covering wound portions of the upper chain and the lower chain, wherein the chain cover is fixed to the lower finishing plate;
• a first coil spring and a second coil spring elastically supporting the first connection block and the second connection block connected to the first connection wire and the second connection wire toward the insertion part to maintain a linear state of the upper chain, wherein the first coil spring and the second coil spring are configured to be stretched to generate elastic restoring forces, so as to transfer external forces to both ends of the upper chain through the first connection block and the second connection block, wherein the first coil spring has a proximal end directly connected to the first connection block and a distal end directly connected to a fixed end of the first guide rail, and wherein the second coil spring has a proximal end directly connected to the second connection block and a distal end directly connected to a fixed end of a second guide rail;
• and
• a third coil spring and a fourth coil spring elastically supporting the third connection block and the fourth connection block connected to the third connection wire and the fourth connection wire toward the insertion part to maintain a linear state of the lower chain, wherein the third coil spring and the fourth coil spring are configured to be stretched to generate elastic restoring forces, so as to transfer external forces to both ends of the lower chain through the third connection block and the fourth connection block, wherein the third coil spring has a proximal end directly connected to the third connection block and a distal end directly connected to the fixed end of the first guide rail, and wherein the fourth coil spring has a proximal end directly connected to the fourth connection block and a distal end directly connected to the fixed end of the second guide rail.