of the tray it is possible for the deck plate to receive the tension of the film acting on the tray through the packaged item application_number US 30195605 A description fig3 shows a general side view of the device in which touch bars 2 disposed equidistantly on endless chains 1 cause trays 4 to advance at equidistant intervals in the direction of the arrow along the upper surface of a horizontal conveyance path 3 by the rotational movement of the chains 1 a general frame 8 comprising four corner pillar members 5 a ceiling plate 6 provided on top of these pillar members 5 and a base plate 7 provided below the pillar members 5 is composed in such a manner that a sealing frame set 9 and a sealing base 10 are disposed respectively in upper and lower regions of the general frame 8 and the seal base 10 and the sealing frame set 9 are moved upwards and downwards by means of a first lift mechanism 11 and a second lift mechanism 12 respectively a band shaped cover film 14 wound and held on a first reel 13 moves at the same speed as the chains 1 through the lower region of the sealing frame set 9 and it is wound up onto a second reel 15 fig1 is a partial enlarged diagram of fig3 in which the aforementioned general frame 8 travels back and forth reciprocally 19 20 in concordance with the conveyance pitch of the trays 4 by means of forward and reverse rotation of a screw rod 17 which is operated by a motor.