1. Test overview.

This test is used to calibrate the green LED at the bottom of the film carrier which is used to detect the presence of film.
A sensor, which is opposite the bottom LED, receives part of the signal and determines the light level. This level does not correspond to any present film in the film carrier When a film is inserted, the light level decreases, and the scanner thus knows that a film has been inserted. The SCAN button of application DKS becomes accessible.
If it it incorrectly calibrated, the SCAN button of application DKS can remain inaccessible, even if a film is inserted. On the other hand, the button can randomely become accessible (influenced by the room light).

2. Test conditions.

This test relates to the 135 Film carrier inserted in the scanner.
The 135 Film carrier must be inserted in the scanner to carry out this test.
No film must be inserted in the film carrier for this test.
The acceptance of the test is automatic.
The value of calibration of the LED is saved in the file im1500data.ini, in chapter FILM_CARRIER_135, at the line FILM_DETECTION_THRESHOLD.

3. Pre-requirements.

To ensure that the LED will not change of position (because of vibration for example), which could influence the intensity of the light signal, and thus the value of calibration of the LED, the LED must be glued. Cyanoacrylate glue is recommended.

4. Test realisation .

Click on RUN to carry out the test. A message indicates to withdraw any film of the film carrier. Click on OK then after a few seconds, the value of calibration of the LED will be displayed on the screen. This value will be saved.

5. Test acceptance.

There is no higher limit for this test, on the other hand the lower limit is fixed at 20.
Note : a value of 200 functions as well as a value of 40, since the software makes a comparative measurement between the value without film and the value with film.

6. Other affected tests.

If the value of calibration of the LED is incorrectly calibrated (for example: calibrated value = 180, true value = 40), that can have a negative impact on all the tests where a film needs to be scanned (the film may not be properly detected and thus incorrectly taken). But that does not directly influence on any test results.

7. Trouble shooting.

• The value of calibration is below the lower limit (20) : ): This means that the light signal is insufficient. Try to polish the LED to increase the signal, or to direct it differently so that the signal is more centred on the sensor.
• Several consecutive measurements give very different values : c: this means that the signal is unstable. Initially try to block any external light which can have an influence on the gauged value. Then check that the LED does not move in its housing. As a last resort, the interface board of the film carrier can be failing. It should be noted that a test in debug mode DEBUG LED POLLING (accessible only on mode PROD) enables to do 100 consecutive measurements and to observe the variation of the value.