alv report( when click on execl button data downloading)

Hi,

I need a alv report when i execute this report its show the out put in alv display and when i click on the execl button its auto matically down load the data.

i already done a report which display alv grid then if i click the print overview button and then execl button its downloaded.

but i need a functinallity if i directly click on the execl button and data is down loaded.

pls help me regarding this, send me some coding for this.

Thanks