| 主权项 |
1. A measurement device (800, 900) for measuring a characteristic reading distance of an individual in a natural posture for near vision, wearing eyeglasses comprising a lens and a frame, the device comprising:
a portable or freely movable reading medium (810, 910) presenting a plane display portion (820, 920) suitable for displaying signs; and a measurement subassembly (840, 940) including at least one ultrasound emitter member (850, 950) and at least one ultrasound receiver member (850, 950), wherein the emitter and receiver members (850, 950) are carried by the reading medium (810, 910), and wherein at least one of said members, referred to as the first measurement member (850, 950) possesses a measurement axis (AM1, AM2, AM3, AM4) along which emission or reception by the first measurement member is optimally provided and that is inclined relative to the plane of the display portion (820, 920) by a constant angle (GAMMA2, GAMMA3) lying in the range from 10 degrees to 80 degrees, and wherein, at least a portion of the signal received by the receiver member being reflected by the lenses or frame of the eyeglasses worn by the individual, said device includes an electronic processor unit that is suitable for extracting from the ultrasound signal received by the receiver member that portion of said signal that is reflected by the lenses or the frame of eyeglasses worn by the individual, to the exclusion of the portion of said signal that is reflected by the individual's skin. |
