| 摘要 |
PROBLEM TO BE SOLVED: To accurately calculate the speed of particles flying in a very small air gap formed between two objects by clearly imaging the particles. SOLUTION: Bias voltage containing AC component is applied between an image carrier 5 and a developing roll 6, and toner particles fly in a very small air gap between the image carrier 5 and the developing roll 6. The AC component and phase of the bias voltage are controlled, a pulse is output from a pulse generator 1, and in synchronization with the pulse, light for a very small time is radiated from a laser device 2 to the toner particles. The toner particles are imaged by a camera 3. Imaging is performed twice at a designated time interval, and the flying speed of toner particles is calculated from two static images by an image processor 4. Since the irradiation time of laser light is short, an image of particles substantially in the stationary state can be obtained, and since the particles are not fused even with high-energy laser light, imaging can be performed favorably. The toner particles flying in the same direction can be imaged in a desired timing by the pulse generator 1.
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