Patent ID: 7884812

Claim:
A liquid crystal projector system for regulating use of a liquid crystal projector, comprising: an external computer for operating the liquid crystal projector, the external computer being connected to the liquid crystal projector by radio or wire and including liquid crystal projector controlling software for controlling the liquid crystal projector; the liquid crystal projector comprising operation means for operating the liquid crystal projector, the operation means including means for entering a command to control the liquid crystal projector via key entry; means for registering a password in the liquid crystal projector; means for determining whether a password is registered in the liquid crystal projector in response to a power supply of the liquid crystal projector being turned on; means for inhibiting operation of the liquid crystal projector by the operation means, as well as for waiting until a password is received from the external computer in response to detecting that the password is registered in the liquid crystal projector; means for comparing, in response to receiving the password from the external computer, the received password with the registered password and for allowing operation of the liquid crystal projector by the external computer and nullifying operation of keys of the operation means in response to the means for comparing indicating that both the registered password and the password received from the external computer coincide with each other; and means for determining a number of times an erroneous password is entered and inhibiting operation of the liquid crystal projector, except a power-off operation of the liquid crystal projector, by nullifying operation of keys of the operation means, except operation of a power key provided in the operation means, in response to determining that the number of times an erroneous password is entered exceeds a predetermined number of times.