US Patent 8137324 Syringe with internal safety device

A syringe includes a syringe cylinder, a sealing plug movably disposed within the syringe cylinder, and with a plunger cooperating with the sealing plug. A safety device prevents a sliding back of the sealing plug within the syringe cylinder in any position the sealing plug assumes within the syringe cylinder. The safety device has a locking element which engages at the plunger in any position the plunger assumes within the syringe cylinder. The locking element is attached to a retaining fixture and protrudes from the retaining fixture same such that an attachment point of the locking element is closer to the sealing plug at the retaining fixture than the free end of the locking element opposite of the attachment point.