The 3XX Scanner is a low-volume scanner that uses an of-the-shelf fluorescent lamp. The lamp was found to have the following deficiencies:
- Its brightness level was much lower than the peak brightness expected from this lamp
- The uniformity of brightness across the lamp was poor
The temperature across the lamp was measured on the glass surface using thermocouples. The temperature was found to be in the range of 131-205 deg F. The lower brightness in the lamp was attributed to the higher operating temperature. This in turn, resulted in poor image quality.
The lamp was modeled as an axi-symmetric heat transfer problem. The heat loss due to natural convection and radiation was modeled using PATRAN and the results from simulation agreed with the experimental data collected.
The lamp sub-system was redesigned to include an Aluminum extrusion and a thermal conductive layer (Chotherm) between the lamp and the extrusion. The analysis showed that temperature across the lamp varied from 120 to 130 deg F. The temperature non-uniformity was reduced from 74 deg F to 10 deg F. The reduction in operating temperature resulted in improved brightness and enhanced image quality.
