| 摘要 |
PURPOSE:To obtain a spatial filter for measuring the moving speed of an object dispensing with any lens system by receiving light obtained through a slit of a light shielding plate with two optoelectric elements to perform a difference computation of the received light output. CONSTITUTION:As an object reaches the point P1 on the surface 1 to be detected, light beams from the point P1 starts to irradiate an optoelectric element 10 through a slit 12 of a light shielding plate 11 and subsequently, when it reaches the point P2, the element 10 is irradiated totally. This section is made as semi- sensitive area 14. Then, the element 10 maintains the state of the total irradiation from the point P2 to P3. This section is made as totally sensitive area 15. Then, the light receiving elements 9 and 10 all provide the area 14 from the point P3 to P4 and likewise, repeatedly do the areas 14 and 15 while moving from the point P4-P6.... Thus, received light outputs each trapezoidal in the shape are obtained on the output sides of the elements 9 and 10 and these outputs produces a frequency signal comprising an AC trapezoidal wave by performing a difference computation through a differential amplifier. Based on this, the moving speed of an moving object can be measured. |
