Abstract: Portable platform assemblies, e.g., tray, desk, or shelf, are provided for placement on the backrests of chairs or seats or similarly vertical surfaces. More particularly, the subject invention pertains to platform assemblies that can be placed on the backrest of a front seat in a vehicle, for example, but not limited to, an automobile, and are useful to someone sitting in the back seat of the vehicle. The tray or shelf assembly can be extended, as well as adjusted to a variety of angles useful for writing, reading, eating or other uses. The platform assembly also provides a safety feature that allows the platform to be automatically collapsed and folded upwards or downwards when sufficient pressure is applied at or near the front of the platform assembly.

Abstract: A tray assembly for mounting on the back of a first seat, such as a front seat of a car, that is disposed substantially in front of a second seat, such as a back seat of a car, to permit a user to sit on the second seat and utilize the tray assembly. The tray assembly includes first and second inverted generally U-shaped hooks. Each of the hooks has first and second legs. Each of the first legs extends along a front face of the first seat and each of the second legs extends along the rear face of the seat back of the first seat. First and second laterally spaced cross members extend between the second legs along the rear face of the first seat. A generally rectangular has one side hinged to one of the cross members and first and second oblique supports extending from a slip fit with spaced parts of a second side to a hinged connection at the respective second legs.

Abstract: A tray assembly for mounting on the back of a first seat, such as a front seat of a car, that is disposed substantially in front of a second seat, such as a back seat of a car, to permit a user to sit on the second seat and utilize the tray assembly. The tray assembly includes first and second inverted generally U-shaped hooks. Each of the hooks has first and second legs. Each of the first legs extends along a front face of the first seat and each of the second legs extends along the rear face of the seat back of the first seat. First and second laterally spaced cross members extend between the second legs of the first and second inverted generally U-shaped members along the rear face of the first seat.