Patent ID: 8551423

Claim:
A liquid supply device using a check valve, comprising: a pump sucking a sample from a pipe and discharging the sample; a pressure sensor detecting a pressure in a pipe on the downstream side of the pump; a control device controlling the pump depending on a pressure detected by the pressure sensor; a first check valve positioned on the suction side of the pump; and a second check valve positioned on the discharge side of the pump, wherein at least one of the first check valve and the second check valve includes a ruby ball occluding an opening of a flow channel, a sapphire valve seat contacting with the ruby ball to occlude the opening, a light source applying light to a part of the ruby ball, and a photodetector detecting the light from the light source, and wherein the control device controls the pump based on determining whether or not a change in pressure and/or flow rate of the solution in the pipe is caused by a malfunction of the at least one check valve depending on a correlation between a signal for opening/closing of the at least one check valve from the photodetector and the pressure detected by the pressure sensor in each cycle of a pumping operation.