section 14 to the data buffer 15 is started in a period of 6 encoded data sd 1 to sdn n means a number of pieces of the predetermined data amount dc are transferred at 7 when the count value of data clocks bck outputted together with the encoded data sdata from the jpeg compressing section 14 which are counted by the stored data amount detecting section 19 has reached a quantity corresponding to the predetermined data amount dc an active pulse is outputted to the stored data amount detecting signal sf at 8 when an active pulse is outputted to the transfer data amount detecting signal tf in order to secure a minimum back blank period tbb from an end of output of the last odata odn to a rising edge of the external synchronizing signal sync an active pulse is outputted to the back blank signal bb after an elapse of the minimum back blank period bbc in the back blank period timer section 22 at 9 an active pulse is outputted to the synchronizing signal hs in response to the stored data amount detecting signal sf being at a timing later in output of an active pulse between the stored data amount detecting signal sf and the back blank signal bb at 10 in the timing generating section 17 a low level active pulse of the external synchronizing signal sync for a preset period is outputted in response to an input of the synchronizing signal hs fig3 shows a timing chart in a period longer than that of fig2 including three external synchronizing signals sync showing operations of.