What's the difference between "0" and "?" of the color measurements?

In the process of daily showing, cinema projectors occasionally encounter that the color measurement value is "0" or "？" when using color measuring device. They are really confused by the two kinds of display situation. What is the cause and what is the difference between the two kinds of display? How to restore the luminance measurement to normal state? And will it affect the actual brightness of the projector?

When the projector does not light the projector, the color measurement value is 0; when the projector lights up, the information of the current light output will be displayed. Color measurement is helpful for operating users to adjust X, Y, Z axes of xenon lamp, and to check the output state and stability of light.

Optical output mode:

Routine mode: Users can choose "routine mode" by choosing navigation bar - Installation - lamp - lamp adjustment. When this mode is selected, the "lamp current regulation" in the conventional mode parameters becomes an adjustable state. When the user needs to adjust the output of the projector, they only need to adjust the current of the lamp of adjusting the slider, and the required color measurement can be obtained by changing the power of the projector.

You can choose a new value by adjusting the slider or clicking the up and down control button of the selection box to adjust the light button, or the method of clicking the text box to change the new number of the keyboard. Current light output and lamp power will change accordingly.

If the cinema projector finds that the color measuring value is still 0 after opening the xenon lamp, and it does not change with the change of the regulating current. It means that the software operation of the light sensor calibration is needed, which is not caused by the hardware failure.