| 摘要 |
An electronic measuring device 2 comprising a tape 20, a source of light 4 and at least one photosensitive component 22 is disclosed. The photosensitive component is disposed on one side of said tape and the light disposed on the other side and orientated such that the light is directed onto the tape and towards the photosensitive component. The invention is characterised in that the tape is at least partially transparent and of laminar construction wherein at least one of the laminae is woven such that the light casts a shadow of the weaving pattern onto the photosensitive component, such being coupled with processing electronics adapted to repeatedly capture the image thereon at a predetermined frequency and, by means of comparison with a formerly captured image, make a determination of the extent to which the tape has been displaced over the frequency period. In a most preferred arrangement, the electronic measuring device is incorporated in an electronic tape measure comprising a housing in which a spool of the tape is mounted, said housing having an opening through which one end of the tape extends and can be subsequently withdrawn. |
