A check processing system enables determining if tampering has occurred while sending check image information captured by a check processing device to a server. The expansion portion of the bladder has a central portion, shoulder portions, and sidewall portions. The backlight driver controls a voltage level of the driving voltage according to a number of turn-on periods of the driving voltage during the communication period. The first slider and the second slider are overlapped relative to each other in the vertical direction. The output jitter of the TIAlimiter is measured for a number of frequency settings to obtain the output jitter response.