The White Screen Phenomenon

Aug 12, 2021

 

I am a firm believer in the use of thermal imaging technology. In fact, I believe it should be used in every incident. However, there may be times when the information obtained on the thermal imager (TI) screen may be confusing. You may even think the TI is not working properly. One of these concerns is what I like to call the “white screen phenomenon.”

There are several reasons this white screen phenomenon could occur. Let’s break these reasons down. I was recently providing TI training to a fire department, and the members asked about a “whiteout” effect they had seen on their TI. Have you ever seen an effect like that? Let’s look at what can cause this issue and what you can do to remedy the situation.

Any recent TIs and those that comply with National Fire Protection Association (NFPA) 1801, Standard on Thermal Imagers for the Fire Service, will have a Flash Overheat Indicator. This indicator is key to understanding the white screen phenomenon. Depending on the make and model of your TI, it may or may not have one.

Here’s what NFPA 1801 has to say about an overheat indicator:

NFPA 6.6.4.4 Internal Electronic Overheat Indicator.

6.6.4.4.1 All thermal imagers shall be equipped with an internal electronics overheat indicator that provides a visual warning to the user that the imager might cease to operate properly due to internal overheating.

6.6.4.4.2 The internal electronics overheat icon shall be positioned in the upper center vertical (alarm and operational indicators) section of the viewing area.

6.6.4.4.3 The internal electronics overheat indicator shall be a flashing indicator consisting of a solid red thermometer-shaped image within a transparent equilateral triangle having a red border (see illustration at right).

This overheat indicator will first come on when the TI boots up. Then, it will disappear from the screen, maybe to be forgotten and not seen again. Should the TI get into extremely high heat conditions, which can be experienced such as during repetitive live flashover training fires, and the temperature exceeds its safe operating range, it will give the end-user a warning to remove the TI from the extreme heat. If the TI is not removed quickly enough, a “white screen” appears. Once the TI cools down, simply follow the manufacturer’s instructions. Some TIs may need to be rebooted or have the internal electronics reset.

Older TI models that may be in use today will not have NFPA symbology or safeguards for internal protection. Should these TIs experience extreme high heat conditions, there will be no end-user warning, and the TI may shut down, displaying only a “white screen.” Once the TI has cooled down, it may reboot and operate properly or it may not operate again if any of the internal electronics were damaged. If the electronics were damaged, the TI may need to be returned to the manufacturer for repair.

There are a couple of other causes of a TI white screen. This may occur when all the contents shown within the scene have reached the same temperature, giving the image a bland or low contrast image. This can be experienced when the room has already flashed and the fire has used up all the oxygen, pretty much putting itself out. What you see in the TI display appears like a “white screen” since there are no differentiating temperatures or contrasts between objects such as furniture, walls, and ceilings. To determine if this is what you are seeing, change the contrast in the room by providing ventilation or cooling methods. If you begin to see a difference in the scene through your TI, you’ll know it is still in working order and the white screen was because of scene conditions.

 

One last white screen concern happens when the battery in your TI is at the end of its run time or at the last of the red bar battery indicator. Any features that may also be running, such as a digital video recorder, are using this same battery power. The TI’s internal electronics cannot keep running. This causes a shutdown or white screen to appear. The simple fix for this is to replace the battery in your TI with a fully charged one.

It’s important to note poor battery maintenance can cause many issues for any TI, in addition to potentially causing white screens. For instance, running TI batteries down completely or “deep discharging” will eventually damage the battery cells. This practice may cause the charger to falsely indicate a full charge on batteries that are damaged or will no longer hold a full charge. To prevent this, do not operate the TI for more than 10 minutes once the red battery life indicator has become activated, and do not run the TI past the point where the display shuts off.

Training for all the conditions your TI may experience is essential. And, understanding the capabilities of your TI will help you better interpret what you see on the display. If you experience the white screen phenomenon, do a quick check:

  1. Did I see an overheat indicator on the screen?
  2. Am I in conditions that may indicate that the internal electronics have overheated?
  3. Is it possible that all items in this scene are a similar relative temperature?
  4. Was/is my TI’s battery very low?

If you want to incorporate best practices into your TI training, be sure to understand if your TI offers an overheat indicator and teach your team to quickly spot that warning icon on the display. In addition, practice using your TI in scenes with little difference in temperature; with training, you’ll be able to more easily notice when the contrast decreases between objects. And finally, implement a strong battery management policy to maintain the health and dependability of your TI batteries. With these practices and training, your department will be able to continue using your TIs on every call. They are truly great life and property-saving technology.

 

This article by Manfred Kihn was published in Fire Apparatus Magazine Magazine in July issue 2021.