How to manage multiple screen in kivy?

Question

I am using kivy to scan cards.How do I manage multiple screens . I wanted to capture the card first and the captured card should be passed to tesseract?

from kivy.app import App
from kivy.lang import Builder
import time
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from PIL import Image, ImageEnhance, ImageFilter
import pytesseract
from kivy.uix.button import Button


Builder.load_string("""
<CameraClick>:
    orientation: 'vertical'
    Camera:
        id: camera
        resolution: (640, 480)
        play: False
    ToggleButton:
        text: 'Play'
        on_press: camera.play = not camera.play
        size_hint_y: None
        height: '48dp'
    Button:
        text: 'Capture'
        size_hint_y: None
        height: '48dp'
        on_press: root.capture()

<SettingsScreen>:
    BoxLayout:
        Button:
            text: 'My settings button'
        Button:
            text: 'Back to menu'
            on_press: root.manager.current = 'menu'
""")


class CameraClick(BoxLayout):
    def capture(self):
        '''
        Function to capture the images and give them the names
        according to their captured time and date.
        '''
        camera = self.ids['camera']
        timestr = time.strftime("%Y%m%d_%H%M%S")
        camera.export_to_png("reading.png".format(timestr))
        print("Captured")


class SettingsScreen(Screen):
    def card(self):
        im = Image.open(r"readimg.png")
        p = pytesseract.image_to_string(im, lang='eng', config='-psm 6')
        print p
        return Button(text=p)


# Create the screen manager
sm = ScreenManager()
sm.add_widget(CameraClick(name='menu'))
sm.add_widget(SettingsScreen(name='settings'))

class TestApp(App):

    def build(self):
        return sm

if __name__ == '__main__':
    TestApp().run()

I am new to kivy I wanted to know how to manage multiple screens.How to display the content of the card from tesseract in another screen?