Polar coordinate display device employing raster scan scheme

Claim 1

A polar coordinate display device employing a raster scan scheme, said device comprising: input means for converting vector data of a plurality of measurement points supplied in synchronism with a measurement scan into polar coordinate data, and for outputting the converted data; display means including a screen for displaying the polar coordinate data by a raster scan scheme; display image memory means for storing polar coordinate data output by said input means, and for reading out the stored polar coordinate data after a delay time corresponding to one measurement scan; first and second image memory means each having a memory format corresponding to the screen of said display means; write control means for producing graph data including means for interpolating the delayed polar coordinate data read out from said display image memory means, and for executing a write-in and deletion cycle wherein the graph data is alternately written in and deleted from said first and said second image memory means according to their memory formats, the write-in and deletion cycle being executed so that, when the graph data is written in one of said first and said second memory means at one measurement scan, graph data that has been stored during a preceding measurement scan is deleted from the other one of said memory means; read control means for executing a readout cycle for said first and said second image memory means in a time divisional manner with the write-in and deletion cycle, including means for simultaneously accessing both said first and said second image memory means according to their memory formats in synchronism with a raster scan of said display means, and for reading out graph data corresponding to one measurement scan and graph data corresponding to the previous measurement scan from said first and said second image memory means while maintaining continuity of data; and synthesizing means for synthesizing the graph data read out from said first and said second image memory means and maintaining the continuity of data, and for supplying the synthesized graph data to said display means for display in real time.