Abstract: An automatic mechanical pencil has a tubular piece removably connected to a barrel cylinder, and a slider for frictionally holding a lead and being movably disposed in a front portion of the tubular piece. A lead chuck is disposed in the barrel cylinder for releasably holding the lead so as to allow forward movement of the lead but prevent backward movement thereof. A first spring urges the slider forward and the lead chuck backward so that when a writing front end of the writing instrument is released from a writing surface, the lead is automatically fed by urging the slider forward. A lead reservoir is disposed rearwardly of the lead chuck to supply the lead to the lead chuck. The lead reservoir has a reservoir main body, a pipe holder connected to a front end of the reservoir main body and having a guide projection, and a stopper disposed around an outer periphery of the pipe holder and having a receiving groove engageable with the guide projection.

Abstract: A writing instrument is capable of functioning both as an automatic mechanical pencil and as a shaking-type mechanical pencil. The writing instrument has a barrel cylinder constituted by a front cylinder detachably connected to a rear cylinder. A slider is disposed at the front end of the barrel cylinder, and a lead chuck, such as a ball chuck, is disposed rearwardly of the slider. A slider spring urges the slider forward and urges the lead chuck rearward. A lead reservoir is movably disposed rearwardly of the lead chuck. Around the outer periphery of the lead reservoir, a weight is disposed to undergo back-and-forth movement in an axial direction. On the outer periphery of the lead reservoir is disposed a weight-receiving cylinder against which the rear end of the weight abuts when the writing instrument is shaken. A knocking spring urges the weight-receiving cylinder forward and urges the lead reservoir rearward.

Abstract: An automatic mechanical pencil has a tubular piece removably connected to a barrel cylinder, and a slider for frictionally holding a lead and being movably disposed in a front portion of the tubular piece. A lead chuck is disposed in the barrel cylinder for releasably holding the lead so as to allow forward movement of the lead but prevent backward movement thereof. A first spring urges the slider forward and the lead chuck backward so that when a writing front end of the writing instrument is released from a writing surface, the lead is automatically fed by urging the slider forward. A lead reservoir is disposed rearwardly of the lead chuck to supply the lead to the lead chuck. The lead reservoir has a reservoir main body, a pipe holder connected to a front end of the reservoir main body and having a guide projection, and a stopper disposed around an outer periphery of the pipe holder and having a receiving groove engageable with the guide projection.

Abstract: A writing instrument is capable of functioning both as an automatic mechanical pencil and as a shaking-type mechanical pencil. The writing instrument has a barrel cylinder constituted by a front cylinder detachably connected to a rear cylinder. A slider is disposed at the front end of the barrel cylinder, and a lead chuck, such as a ball chuck, is disposed rearwardly of the slider. A slider spring urges the slider forward and urges the lead chuck rearward. A lead reservoir is movably disposed rearwardly of the lead chuck. Around the outer periphery of the lead reservoir, a weight is disposed to undergo back-and-forth movement in an axial direction. On the outer periphery of the lead reservoir is disposed a weight-receiving cylinder against which the rear end of the weight abuts when the writing instrument is shaken. A knocking spring urges the weight-receiving cylinder forward and urges the lead reservoir rearward.