Image Engineering iQ-LED Technology Statement Instructions

Image Engineering iQ-LED Technology Statement

Specifications

• iQ-LED Technology
• Spectral Calibration
• LED Lifetime: Thousands of hours
• Thermal Management System

Product Usage Instructions

• iQ-LED and Calibration
  LEDs degrade over time and require regular calibration for optimal performance. iQ-LED technology utilizes an internal spectrometer to measure the spectral distribution and energy of each LED channel, adjusting intensity values to maintain the desired light spectrum

• Maximum Intensity of Illuminants
  The iQ-LED Software allows setting maximum intensity per illuminant to ensure longevity. Avoid setting channels to maximum intensity except during warm-up

• Temperature Control
  iQ-LED devices feature a thermal management system to control LED temperature for stability. Avoid running all channels at maximum intensity to prevent overheating and triggering safety switches.

SCOPE

This document shall provide additional information when using iQ-LED Technology. It specifically refers to the section “3.3.2 Spectral Calibration” in the manual1.

The document states:
Light-emitting diodes degrade over time. This process decelerates after the first 500 operating hours. As a result, a calibration of the light source needs to be performed regularly. In the first 600 hours, we recommend every 50 operating hours. After the first 600 hours, we recommend every 150 operating hours. We want to provide more detailed information regarding this statement.

IQ-LED AND CALIBRATION

• LEDs, in general, change during their lifetime. They will degrade in intensity from a long-term perspective (thousands of hours of usage). In the short term (within the first hundreds of hours), it is possible to see an increase in intensity.
• iQ-LED technology uses an internal spectrometer to perform a self-calibration. Each LED channel’s spectral distribution and absolute energy are measured during this step. The calibration data is then used to adjust the intensity value per channel to reach the best fit of the light source’s desired spectrum.
• If an LED degrades over time, the calibration step will ensure that the LED is controlled with a higher intensity to reach the same light intensity as before.
• Example : Channel 5 has an intensity value of 40.8%, resulting in the desired light intensity. After the self-calibration measured that the light intensity is not the same anymore, it will correct the intensity value to a slightly higher value of, e.g., 41.1%, so the light intensity again matches the original.
• No channel should be at its maximum intensity, as that does not leave room for correcting a slight degradation over time.

https://www.image- engineering.de/content/products/software/led_control_software/downloads/iQ- LED_software_manual.pdf

MAXIMUM INTENSITY OF ILLUMINANTS

• The iQ-LED Software has a feature to define the maximum intensity per illuminant to ensure that the generated illuminant has enough headroom to be reproduced over the iQ-LED device’s expected lifetime.
• See section 4.1 of the manual. The “i” button will provide the maximum possible intensity while considering long-term usage and headroom for long-term degradation.
• Setting single or even all channels to maximum intensity is not an intended operation mode and should not be used at any time besides during the intended warm-up.

TEMPERATURE CONTROL

• iQ-LED devices have a thermal management system to keep the LEDs within a controlled temperature range to maximize the intensity stability. This thermal management is designed for normal usage and recommended maximum intensity. Significantly higher intensities (such as all channels to maximum) can potentially overheat the device and trigger a safety switch that will turn off the element.
• If an overheating occurs and you observe the device turn itself off, please ensure that the same operating conditions are not used again as you are outside of the operation range that can be used for an extended period.
• Reduce the intensity and check if the thermal management is compromised for any other reason, e.g., a blocked air stream into the device or an environment with temperatures outside the operation temperatures defined in the datasheet.

USAGE OF IQ-LED IN THE FIRST HUNDREDS OF HOURS

• As stated in the manual and cited in section 1, Image Engineering recommends a higher calibration frequency within the first 600h of lifetime. That will ensure constant illumination and prevent those possible effects of LED “burn-in,” which could change the spectrum.
• Some customers that use the iQ-LED Technology in a 24/7 environment (like production lines) would like to keep the recalibration at the lowest possible frequency. We see two strategies if a frequency of ~50h is not feasible for your application.

IQ-LED MONITORING

• Every iQ-LED device is equipped with an absolute calibrated spectrometer, which can also be read out via API. So, a change in the emitted spectrum can be detected by comparing the current spectrum with a reference spectrum. A recalibration can then be triggered when a significant deviation is detected.
• Instead of using a fixed frequency of recalibration, the recalibration can be triggered based on the actual need. As the recommended 50h frequency has some margin, the accurate recalibration based on measurement is expected to be longer and will increase within the first 600h of operation.
• If changes in the emitted spectrum after recalibration are of concern, the software (and API) allows you to create illuminants based on older calibrations. Thus, it is possible to “undo” a recalibration if this did not have the intended effect.

BURN-IN
If the recommended operation with an increased frequency of self- calibration is not possible, a burn-in phase can be an option. In this case, the device will be operated outside of the intended environment for a certain period, so the frequency of recalibration can be lower afterwards.

If this is the process you would like to follow, please be aware:

• The period of 600h is calculated based on normal usage. Normal usage means that illuminants with an intensity of or below the maximum intensity (see section 3 of this document) are used.
• To reach burn-in within 600h of operation, an intensity significantly below the maximum intensity (~30% of maximum) is sufficient.
• Creating a sequence of different illuminants and regularly changing the illuminants is advised (e.g., changing between illuminants every 60).
• The device has to be operated via the USB connection when not supervised.

FAQ

Q: How often should I perform calibration on my iQ-LED device?
A: For the first 600 hours, calibrate every 50 operating hours. After that, calibrate every 150 operating hours.

Q: Can I set all channels to maximum intensity?
A: Setting all channels to maximum intensity is not recommended for regular operation, as it may lead to overheating and device shutdown. Only use maximum intensity during the intended warm-up period.

Q: What happens if an LED degrades over time?
A: The calibration process will adjust the intensity values of the LED channels to maintain the original light intensity, compensating for degradation.

References

• Image Engineering - Solutions to test image Quality

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