Simplified safety syringe with retractable self-biased needle

A safety syringe comprising:

• a syringe means including a syringe cylinder having a hollow bore portion for filling liquid medicine therein, and a sleeve portion formed on a front portion of said syringe means having a central opening formed through the sleeve portion, a syringe axis longitudinally defined in a central portion of said syringe means;
• a needle device including a hollow needle portion fixed on a shank portion held in said sleeve portion of said syringe means having at least a biasing socket generally conical shaped recessed in a rear needle portion of said needle device having a longitudinal conical axis obliquely deviating an acute angle from a needle axis which is longitudinally defined in a central portion of said needle device and is aligned with the syringe axis of said syringe;
• and
• a plunger means including a plunger slidably held in said syringe cylinder for boosting liquid medicine in said cylinder for injection through said needle device, and a coupling member embedded in said plunger having an arrow head portion formed at a front end of said coupling member operatively forcibly inserted in said biasing socket to couple the arrowhead portion with the needle device to store a resilient restoring energy of the rear needle portion of said needle device after finishing an injection, and upon retraction of the plunger and the needle device coupled to said plunger into said syringe cylinder, said needle device will be automatically restored and obliquely biased to prevent outwardly re-protruding of said needle device from said syringe means.