Profits are expected to be "significantly" above market expectations at AIM-listed Zytronic, which pleased investor with a surprise trading update.The touchscreen maker said group revenue was running around 8% higher than the same period last year.It explained that the previous trend of increased sales of larger touch products and the significant improvements in margin enjoyed in the first half of the year had continued well into the second.House broker N+1Singer lifted its forecasts for full-year profit before tax (PBT) from £2.7m to £3.2m and earnings per share (EPS) from 14.7p to 17.4p, as well as upping 2015 forecast PBT to £3.4m and EPS to 18.6p."Having already upgraded at the time of the interims in May, it is positive news that mix and margins have continued to improve since then, leading to further increases to our forecasts," analysts wrote."As we have said previously, management reacted quickly to the slower trading 12 to 18 months ago and confidence is being rebuilt, assisted by a strong balance sheet and dividend yield."Shares in Zytronic were up 175 to 259.7p by 12:15 on Wednesday.