Filler font method

The playing time of records is significantly increased by the filler writing process (also known as Rheinsche filler writing ) . For this purpose, the distances between the groove flanks of the record are reduced, depending on the current level ( volume ) of the recording. If the level is low, the groove flanks are cut closer together by the groove control .

In the normal script that was used previously, the slope of the groove was constant and fixed. Depending on the highest level, the groove spacing had to be rigidly adhered to, which, however, meant large spacing in the quiet areas and thus more loss of used carrier material. As a result, the possible playing time of records was limited for a long time.

The fill lettering process was developed by Eduard Rhein (1900–1993) between 1944 and 1948 ; on June 8, 1949, he was granted a patent for it under the number DBP 966210. The (stereo suitable) process forms one of the bases for the long-playing record . Together with the narrow micro-groove , the filler font enables a playing time of up to 25 minutes per page.

The widespread signet at the beginning of the 1950s with the effective advertising word filler font also wrongly suggested to customers that the sound was "fuller" as a result.