| 摘要 |
PURPOSE:To provide ground coffee having a uniform grain size at all times, regardless of a bean quantity and hardness, by detecting the speed of a motor to drive a cutter, and causing a motor control means to control the motor for keeping the detected speed constant. CONSTITUTION:Coffee beans are thrown into a grinder 4 and a start key is turned on. Then, the beans are crushed into ground coffee, due to the rotation of a cutter 4 on the operation of a motor 5. This ground coffee is received by a coffee liquid brew vessel having a paper filter via a guide cylinder. In this case, the speed of the motor 5 is detected by a speed detection means 12 comprising a notched speed counter 10 and an optical sensor 11. Also, the motor 5 is controlled in phase by a control means 13 on the basis of output from the means 12 via a phase control circuit 13, so that the speed of the motor 5 can be kept constant. As a result, the speed of the motor 5 can be kept constant, and the grain size of ground coffee can be made uniform, regardless of the quantity and hardness of coffee beans, the torque of the motor 5, and power supply voltage and frequency. |
