| 摘要 |
<p>PURPOSE:To secure the even luminous intensity of the transmitted light by setting a diffusing filter at the front of a light source of a bar code reader containing an array of LEDs. CONSTITUTION:Each LED of a light source has high luminance and high directivity. The distribution of luminous intensity of the LED has a wave form as shown by BF. This waveform distribution emerges also on the surface of a bar code label 2 if no diffusing filter 5 is provided. The light is diffused but the luminance has no reduction with use of the filter 5. Then an even distribution is secured for luminous intensity as shown by AF.</p> |
