Samsung files a patent addressing OLED Burn-In issues Specifically aimed at Smartphones with Under-Display Fingerprint ID
A Samsung patent application published yesterday caught my attention. The invention relates to technology that prevents display burn-in. Why is that so special? Well, Samsung is specifically aiming their new patent at Smartphones with burn-in due to under-display fingerprint biometrics that unlock smartphones.
Apple acknowledges that burn-in could occur on iPhones with OLED displays noting that "With extended long-term use, OLED displays can also show slight visual changes. This is also expected behavior and can include “image persistence” or “burn-in,” where the display shows a faint remnant of an image even after a new image appears on the screen. This can occur in more extreme cases such as when the same high contrast image is continuously displayed for prolonged periods of time.
We’ve engineered the Super Retina and Super Retina XDR displays to be the best in the industry in reducing the effects of OLED "burn-in." This includes special algorithms that monitor the usage of individual pixels to produce display calibration data. Your iPhone uses that data to automatically adjust the brightness levels for each pixel as needed to reduce visual effects from "burn-in" and to maintain a consistent viewing experience."
So Apple has learned how to "hide" slight burn-in and will reduce the brightness automatically to "hide" the problem. To date there haven't been any lawsuits filed on this issue and so it must be rare or non-existent at this point in time.
However, the issue of burn-in apparently could be amplified with the continual use of something like Touch ID on future iPhone displays.
One of Samsung's latest patent applications filed this week brings up a very specific issue with burn-in that may or may not effect next-gen iPhone's with under-display Touch ID.
Samsung's quick overview found in their patent titled "Electronic Device for Preventing Display Burn-In," states the following:
"The fingerprint sensor may obtain the fingerprint information based on light output from the display. For example, the light output from the display is reflected from the fingerprint of a user making contact with a cover glass and input to the fingerprint sensor. The fingerprint sensor may obtain the fingerprint information based on light output from the display.
"However, as the operation of obtaining the fingerprint information is repeated, a display burn-in phenomenon may occur. In particular, the burn-in phenomenon more severely occurs at an area, which corresponds to the fingerprint sensor, of the display rather than another area of the display."
Samsung points to patent FIG. 1 stating that "The display #120 may adjust the brightness of an area (hereinafter, referred to as a "fingerprint sensing area 120S") corresponding to a fingerprint sensor. The display may increase the brightness of the fingerprint sensing area in proportion to a time in which the finger of the user makes contact with the fingerprint sensing area.
When the user's finger makes contact with the fingerprint sensing area on the display 120, the display may control the fingerprint sensing area 120S to emit light with 300 Lux.
If the fingerprint information is not obtained even if the fingerprint sensing area 120S emits the light with 300 Lux, the display may gradually increase the brightness of the fingerprint sensing area 120S. The brightness of the fingerprint sensing area may be gradually increased until the fingerprint information is obtained.
Technically speaking, a display panel disposed inside the housing and including a plurality of pixels disposed in the display panel, a first printed circuit board interposed between the display panel and the back cover, a second printed circuit board interposed between the first printed circuit board and the back cover, a fingerprint sensor disposed on the first printed circuit board to obtain fingerprint information of a user based on light reflected from a finger of the user making contact with the cover glass, and a processor disposed on the second printed circuit board to adjust a brightness of first-group pixels disposed at an area corresponding to the fingerprint sensor.
The processor may attempt to obtain the fingerprint information by emitting light of the first-group pixels with first brightness, when the user makes contact with the cover glass with the finger, and allow the first-group pixels to emit the light with a second brightness brighter than the first brightness, when the finger of the user is detached from the cover glass and then makes re-contact with the cover glass.
Considering that Samsung is supplying Apple with displays for iPhone 12 we'd like to think that Samsung has shared this information with Apple so that over time, after thousands of Touch ID imprints, burn-in will be avoided.
Then again, Apple's great display and optical teams have likely figured away around this issue for future Touch ID iPhones with under-display sensors arriving this year.
Yet with that said, if Samsung, Apple's supplier of displays, has decided to actually file a patent to avoid burn-in on future Galaxy smartphones with under-display fingerprint sensors in the future, the issue has to be taken seriously and one to watch for as new iPhones with on-screen Touch ID hit the market later this year.