Metal grilles and grates are mounted on exterior of windows of a building. Conventional grilles and grates are permanently affixed into the wall adjacent to the window in order to prevent unauthorized entry. For escape in emergency, the grilles and grates have a door which can be open and closed. When the door is closed, a lock mechanism is employed However, it always happens that the key for releasing the lock mechanism can not be found in emergency.
A further window grille latch system has been disclosed in U.S. Pat. No. 4,263,747 by Coltrin et al. The window grille latch system comprises a hinge and a latching assembly mounted on the wall adjacent to both sides of the window. The grille is hinged with the hinge at one side and locked with the latching assembly at the other side. With a cable being pulled, the latching assembly releases a cylindrical penetrator member, so that the grille can be "open" for escaping.
Such window grille latch system includes a large number of components which is complex and difficult for manufacturing and fabricating. Also, it is rather expensive. In operation, separating upper and lower latch member in order to release the cylindrical penetrator member requires great force. Once there is any component out of order, the movement of upper latch member will be very difficult.