Eraser dispenser and writing instrument equipped with eraser dispenser

A writing instrument comprising:

• means defining an inner barrel having forward and rearward portions and having therein a storage compartment for storing writing leads;
• an outer front barrel disposed over and encircling the forward portion of the inner barrel;
• a writing tip connected to the forward end of the front barrel;
• means mounting the inner barrel to undergo limited axial displacement in forward and rearward directions within the outer front barrel but not angular displacement relative thereto;
• lead-advancing means for incrementally advancing a lead fed from the storage compartment to the writing tip in response to forward axial displacement of the inner barrel;
• an outer rear barrel disposed over and encircling the rearward portion of the inner barrel;
• means mounting the outer rear barrel to undergo angular displacement about the inner barrel but not axial displacement relative thereto;
• an eraser holder disposed within the rearward portion of the inner barrel and releasably holding an elongate eraser;
• and means mounting the eraser holder to undergo axial displacement in forward and rearward directions within the inner barrel in response to angular displacement of the outer rear barrel in opposite directions to thereby effect retraction and extension of the eraser relative to the rear end of the inner barrel according to the direction of angular displacement of the rear barrel.