e-ink display ghost image

Question

There is a ghost image (not sure if that is the right term) on my e-ink display from waveshare:

Is there any way I can fix this, or do I have to replace the display?

The ghosting appeared after several days of use and I think it appeared because I didn't put the display to sleep after updating it. Can anyone confirm that adding the .sleep() call would prevent this to happend again?

    import epd2in13

    def showImageOnScreen(image):
        epd = epd2in13.EPD()
        epd.init(epd.lut_full_update)
        epd.clear_frame_memory(0xFF)
        epd.set_frame_memory(image, 0, 0)
        epd.display_frame()
        epd.sleep()

Answer 1

To stop this happening you need to run a 'scrub' cycle frequently. Each day (well early morning) I run a cron job that sets all the pixels red, then black then white (I have the Pimoroni display) including the display frame / edge.

My code is based around their support library but should give you a basic idea:

class InkyScreen:

    def __init__(self, Colour, Rotate = 0, Size = (212, 104)):

        if Colour.upper() not in ['RED', 'YELLOW', 'BLACK']:
            Colour = 'RED'
        if Rotate not in [0, 90, 180, 270]:
            Rotate = 0
        if Size not in [(212, 104), (104, 212), (400, 300) , (300, 400)]:
            Size = (212, 104)

        self.colour = Colour
        self.border = Colour
        self.rotate = Rotate
        self.image_obj = Image.new('P', Size)
        self.screen_image = ImageDraw.Draw(self.image_obj)
        self.width = Size[0]
        self.height = Size[1]
        self.dev = InkyPHAT(Colour)

    def clear(self, Colour = InkyPHAT.WHITE, Border = InkyPHAT.WHITE):

        self.screen_image.rectangle([(0 ,0), (self.width, self.height)], \
                            fill = Colour, \
                            outline = None )
        self.border = Border


    def show(self):

        self.dev.set_image(self.image_obj.rotate(self.rotate))
        self.dev.set_border(self.border)
        self.dev.show()

    def scrub(self,cycles = 3):

        colours = [InkyPHAT.RED, InkyPHAT.BLACK, InkyPHAT.WHITE]
        for i in range(cycles):
            for index, colour in enumerate(colours):
                self.clear(Colour = colour, Border = colour)
                self.show()

As your screen has been 'set' for a while, you may want to add a delay of a minute or so between each colour change and run the scrub a few times while checking on it.

The cause is due to the discharge not being complete and leaving some cells 'stuck' in part charged states - hence the ghost image.

Answer 2

The recommended procedure preventing ghost images on e-ink is to fill the display with 100% black, then 100% white, then display the target image:

If this is what you already do, then you just got a low-quality display.