well autumn is here and they look like they could of got wind damage or got dry perhaps .

Japanese acers lose all their leaves in autumn but this looks like wind or full sun damage to me. The leaves literally get burnt and go brown at the edges.

Yes I think as Moon growe and Noseypotter say it is probably wind or sun damage this happens to the same two of mine each year but doesn't seem to affect them in spring when they grow back

ok thank you all for your help will it be best to move them to a more shsded area ?

shaded means have a south facing back garden but have had it split up into 3 differnt gardens

Japanese acers can cope, just, with full sun what they can't cope with is wind… It just burns their leaves and they are left looking tatty. So move them out of the wind and, if possible, into a semi shady area where they don't get full sun in the middle of the day.