Field of the Invention
The present disclosure relates to a system for loading and unloading a cassette and a method for loading and unloading the cassette, more particularly, relates to a system for loading and unloading a cassette for housing precise components, such as a glass motherboard, a variety of substrates, display screens and the like, and a method for loading and unloading such an cassette.
Description of the Related Art
In the production of a current liquid crystal display (LCD), sheet-shaped precise components, such as a glass motherboard, a variety of substrates, display screens and the like, are generally loaded in a housing case, such as a cassette (CST), so as to convey these precise components among production lines for performing different manufacturing processes in a dust-free condition. In these cases, some production lines may be located in different floors such that these precise components should be conveyed between different floors. Generally, a cross-floor convey is realized by a clean lifter.
In the production of the LCD device, take a conveying operation for the glass motherboards in array substrates plant for instance, due to the limitation of the plant structure and production layout, the cassettes are conveyed up and down between a fourth floor and a second floor by the clean lifter. In the clean lifter, a lift cage is driven by a steel wire rope of a cycle type, such that the lift cage vertically raises and falls, and conveys the cassette between different floors (for example, the fourth floor and the second floor). Since the steel wire rope has the property of elongating due to a longtime service, a long convey distance and an increasing load, it is quite difficult to position the lift cage when it stops. However, in the production of the LCD device, with respect to the conveying of the cassette, there is an extremely high accuracy requirement for the stop position of the lift cage, so as to ensure that the cassette will be smoothly conveyed from the lift cage of the clean lifter to a conveying device outside of the lift cage, or from the conveying device into the lift cage, thereby realizing the smooth load and unload of the cassette and preventing the precise components inside the cassette from colliding with something else and thus being damaged.