Stapler with improved driving structure

A stapler, comprising:

• a body having a first shaft connecting portion, a second shaft connecting portion, and a shaft displacement limiting portion;
• a first shaft connected to the first shaft connecting portion of the body;
• a second shaft connected to the second shaft connecting portion of the body;
• a staple driver disposed in the body in a vertically displaceable manner, the staple driver having an installation hole and a hooked hole;
• an elastic unit disposed in the body, an end of the elastic unit being inserted in the installation hole of the staple driver;
• an operation lever having a first hole and a first lower pivot hole, the first shaft being inserted through the first hole;
• a third shaft connected to the first lower pivot hole of the operation lever;
• a pivotably connecting member having a second lower pivot hole and a first upper pivot hole, the third shaft being pivotally connected to the second lower pivot hole;
• a hook member having a second hole, an elongated hole, a second upper pivot hole and a hook portion, the second shaft being inserted through the second hole, the third shaft being inserted through the elongated hole, the hook portion being releasably hooked at the hooked hole of the staple driver;
• a fourth shaft pivotally connected to the first upper pivot hole of the pivotably connecting member and the second upper pivot hole of the hook member, the fourth shaft being slidably abutted against the shaft displacement limiting portion of the body when the hook member is swung;
• and
• a restoring member having a first connecting end connected to the body, and a second connecting end connected to the hook member in a way that an elastic force of the restoring member makes the hook portion of the hook member displace downwardly;
• wherein a first distance is provided from an axis of the first shaft to an axis of the third shaft;
• a second distance is provided from the axis of the third shaft to an axis of the fourth shaft;
• the first distance is smaller than or equal to the second distance.