The support plate may be provided with a rib frame structure including a plurality of ribs in a horizontal direction corresponding to {TAIL ~ a direction} of the first tilt shaft and a plurality of ribs in a vertical direction corresponding to a direction of {HEAD ~ the second tilt shaft} 
The support plate may be provided with a rib frame structure including a plurality of ribs in a horizontal direction corresponding to { TAIL ~ a direction } of the first tilt shaft and a plurality of ribs in a vertical direction corresponding to a direction of { HEAD ~ the second tilt shaft }
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