A cooling device for projector includes a shell, a circuit board, a light machine, a first fins, a fan assembly and a heat dissipation module. The driver device causes the vibrator to produce the driving vibrations using the signal modulated by the modulation circuit, and then causes the vibrator to produce the driving vibrations by controlling the oscillation amplitude in the oscillation loop formed by the vibrator and the gain control amplifier. The end-to-end transactions are completed is just a few seconds or less. Based on the type of delivery, the system determines for each item of correspondence, whether the delivery will be by physical delivery of a printed document, by fax or by e-mail.