Injection device 110 of the present invention, housing 112 is configured to receive a syringe (122) having a discharge nozzle (118); Actuator 114; In the retracted position accommodated in the actuator housing to the discharge nozzle to operate and operating on alternately by syringe, driver 120 to advance the syringe to an extended position where the discharge nozzle extends from the housing; In communication with the actuator and the actuator is operable to move to the locking position (locked position) and unloading in the actuator to operate the drive unit can be operated to advance the syringe king position (unlocked position) to prevent releasing the driving unit includes a locking mechanism 116, that is, the locking mechanism or the housing includes a biasing means (210) integrally formed with suitable for returning to the locking position when the locking mechanism is not working, the locking mechanism. Therefore, there is a need for a separate spring is used to bias the releasable locking mechanism in the locking position. Scanning device, a housing, an actuator, driving the locking mechanism, the biasing means