Light source device of endoscope system

1. A light source device of an endoscope system comprising:

a light source that emits in a flash-emitting mode, wherein said light source flashes in a flash interval that is longer than a field period of an imaging sensor for said endoscope system and for a flash period that is shorter than said field period; and

a light-source controller that controls said light source so that said light source prevents emission in said flash-emitting mode within a reading period that is a period excluding an image period within said field period;

said flash interval being defined as a period from when the flash of said light source commences to when the next flash of said light source commences, and said flash period being defined as a period from when the flash of said light source commences to when the flash of said light source is completed.

2. The light source device according to claim 1 , wherein said light-source controller controls said light source so that said light source emits in said flash-emitting mode within said imaging period, on the basis of a first elapsed time of said field period, a second elapsed time of said flash interval in said flash-emitting mode, and a third elapsed time of said flash period.

3. The light source device according to claim 1 , further comprising a detector that detects a voice signal input;

wherein said light-source controller turns off said light source that is emitting in a normal emitting mode by the completion of a first field period including a time point when said detector detects said input of said voice signal, and controls said light source in said flash-emitting mode starting from a second field period that is the next field period of said first field period.

4. The light source device according to claim 3 , wherein said light-source controller controls said light source in said flash-emitting mode so that a timing of the commencement of the flash of said light source is set to a middle of said field period when said flash interval is close in length to a length of said field period.

5. The light source device according to claim 4 , wherein said light-source controller controls said light source in said flash-emitting mode so that the flash of said light source is stopped until a completion of said reading period and commences after completion of said reading period, when at least one of a first time point and a second time point overlaps with said reading period;

said first time point is the time point when said flash interval has elapsed after the commencement of the flash of said light source; and

said second time point is the time point when said flash period has elapsed after said first time point.

6. The light source device according to claim 1 , said light source controller being configured so that in said flash emitting mode, when a length said flash interval is within a predetermined percentage of a length of said field period, commencement of the flash of said light source is controlled to occur at a middle of said field period.

7. The light source device according to claim 1 , wherein said light source controller controls light source in the flash emitting mode so that the flash of said light source is stopped until a completion of said reading period and commences after completion of said reading period, when at least one of a first-time point and a second time point overlap with said reading period, said first-time point being the time point when said flash interval has elapsed after the commencement of the flash of the light source; and said second time point is the time point when said flash period has elapsed after said first-time point.