python单次运行写入csv成功，循环写入失败

程序运行一次可以正常写入，但是在bbox = (186, 415, 246, 438)上方加了while循环后，循环程序能成功进行，但是写入csv完全空白，连抬头都没有，缩进是检查过了没有问题，

import pytesseract
from PIL import Image
from PIL import ImageGrab
import  pyautogui,time
import csv



csv_file=open('K.csv','w',newline='')
writer=csv.writer(csv_file)
writer.writerow(['名字', '类型'])


pyautogui.click(235, 868)
pyautogui.click(1056, 303, clicks=1, interval=0.0, button='left')


bbox = (186, 415, 246, 438)
im = ImageGrab.grab(bbox)
im.save('1.png')
file = r'D:\python\pycharm\pycharm file\study\1.png'  
image = Image.open(file)
code = pytesseract.image_to_string(image, lang="chi_sim+eng")
code1 = [code]

bbox = (1151, 119, 1388, 158)
im = ImageGrab.grab(bbox)
im.save('2.png')
file = r'D:\python\pycharm\pycharm file\study\2.png'  
image = Image.open(file)
code2 = pytesseract.image_to_string(image, lang="chi_sim+eng")
writer.writerow([code2, code])
pyautogui.scroll(-200)








import pytesseract
from PIL import Image
from PIL import ImageGrab
import  pyautogui,time
import csv




csv_file=open('K.csv','w',newline='')
writer=csv.writer(csv_file)
writer.writerow(['名字', '类型'])


pyautogui.click(235, 868)
pyautogui.click(1056, 303, clicks=1, interval=0.0, button='left')

n=1
while n!=3:
    bbox = (186, 415, 246, 438)
    im = ImageGrab.grab(bbox)
    im.save('1.png')
    file = r'D:\python\pycharm\pycharm file\study\1.png' 
    image = Image.open(file)
    code = pytesseract.image_to_string(image, lang="chi_sim+eng")
    code1 = [code]

    bbox = (1151, 119, 1388, 158)
    im = ImageGrab.grab(bbox)
    im.save('2.png')
    file = r'D:\python\pycharm\pycharm file\study\2.png' 
    image = Image.open(file)
    code2 = pytesseract.image_to_string(image, lang="chi_sim+eng")
    writer.writerow([code2, code])
    pyautogui.scroll(-200)