Drive unit and light-emitting device

A light-emitting device comprising:

• one or more of semiconductor lasers;
• and
• a drive unit configured to control a crest value of a current pulse applied to the one or more of semiconductor lasers depending on color grayscale,
• wherein, in the drive unit,
• in each of a plurality of the current pulses, a rising crest value is largest, and after the rising, the crest value is damped,
• a rising crest value of a pulse of an n+1-th wave is smaller than a rising crest value of a pulse of an n-th wave,
• rising crest values of the current pulses of a second wave and waves after the second wave are determined by a mathematical function expressed as an electric potential change caused by ON-OFF of an RC time constant circuit that is single-end grounded, and
• in the mathematical function, a time constant at an OFF time is larger than a time constant at an ON time, and
• wherein, in a case where a current amount of the current pulse intermittently changes, a visible time constant at the ON time is made smaller by multiplying the time constant at the ON time by a coefficient that is smaller than 1.