| 摘要 |
PROBLEM TO BE SOLVED: To enhance the reliability of illumination light emitted from a plurality of light sources provided at the tip of a portable endoscope. SOLUTION: A step-up circuit 101 is formed on the circuit board of the portable endoscope. When a battery unit is mounted in the portable endoscope, the step-up circuit 101 is connected to a battery 100 via a switch 101. The step-up circuit 101 raises the voltage generated by the battery 100 to a predetermined voltage value. Constant current control circuits 201 to 206 are electrically connected in parallel with the step-up circuit 101. An LED 51 is connected to the constant current control circuit 201. A transistor 211 is interposed between the cathode terminal of the LED 51 and the constant current control circuit 201. The emitter terminal of the transistor 211 is connected to the constant current control circuit 201 via a variable resistance R1. Other LEDs and the other constant current control circuits are arranged in a similar manner. The resistance values of variable resistances R1 to R6 are set so that the LEDs 51 to 56 are uniform in brightness.
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