Patio sliding door lock assembly and method

A key operated lock assembly for a patio sliding door having first and second locking positions for engaging a catch means comprising:

• a cylinder means, a cam wheel means, said cam wheel means including a lug member, said cam wheel means joined to said cylinder means, said cylinder means defining a key receiving slot, a latch member, said latch member for engaging said catch means, said latch member having a semi-circular lug slot, said lug member slidably received in said semi-circular lug slot, an independent rotatable handle member, said handle member rigidly joined to a shaft, said shaft joined to said latch member for rotation therewith, said cylinder means including a tumbler element and a shoulder stud, a first support means, said cylinder means mounted on said first support means, said first support means defining a plurality of tumbler receiving grooves, said shaft having an extension means, said extension means including an axle member, said shoulder stud receiving said axle member, said cylinder means being rotatable to a first locking position by a key for moving said lug member to one end of said semi-circular slot urging said latch member into engagement with the catch means whereat said handle member cannot be rotated and said cylinder means being rotatable to a second locking position by a key for moving said lug member to said other end of said semi-circular slot whereat said handle member can be rotated to disengage said latch member from said catch means.