Liquid supply device, liquid discharge device, and liquid discharge apparatus

A liquid supply device, comprising:

• a liquid discharge head configured to discharge liquid;
• a main tank configured to store liquid to be supplied to the liquid discharge head;
• a first sub-tank tank connected to the main tank and the liquid discharge head, the first sub-tank configured to store gas and liquid;
• a second sub-tank connected to the first sub-tank and the liquid discharge head the second sub-tank configured to store gas and liquid. a first air tank connected to the first sub-tank, the first air tank configured to store gas;
• a second air tank connected to the second sub-tank, the second air tank configured to store gas;
• a first liquid supply pump connected between the main tank and the first sub-tank to supply liquid from the main tank to the first sub-tank;
• and
• a second liquid supply pump connected to the first sub-tank and the second sub-tank to supply liquid from the first sub-tank to the second sub-tank.

A liquid supply device, comprising:

• a liquid discharge head configured to discharge liquid;
• a main tank configured to store liquid to be supplied to the liquid discharge head:
• a first sub-tank tank connected to the main tank and the liquid discharge head, the first sub-tank configured to store gas and liquid;
• a second sub-tank connected to the first sub-tank and the liquid discharge head, the second sub-tank configured to store gas and liquid;
• a first air tank connected to the first sub-tank. the first air tank configured to store gas:
• and a second air tank connected to the second sub-tank. the second air tank configured to store gas, wherein
• one of the first air tank and the second air tank is a negative-pressure air tank configured to supply a negative air pressure, and the other of the first air tank and the second air tank is a positive-pressure air tank configured to supply a positive air pressure, and
• wherein the liquid supply device further includes:
• a decompression air pump connected to the negative-pressure air tank to reduce pressure of the negative-pressure air tank;
• and
• a pressurizing air pump connected to the positive-pressure air tank to pressurize the positive-pressure air tank.

A liquid supply device comprising:

• a first liquid discharge head configured to discharge liquid;
• a second liquid discharge head configured to discharge liquid;
• a main tank configured to store liquid to be supplied to the first liquid discharge head and the second liquid discharge head;
• a first sub-tank connected to the main tank and the first liquid discharge head, the first sub-tank configured to store gas and liquid;
• a second sub-tank connected to the first sub-tank and the first liquid discharge head, the second sub-tank configured to store gas and liquid;
• a third sub-tank connected to the main tank and the second liquid discharge head, the sub-tank configured to store gas and liquid;
• a fourth sub-tank connected to the third sub-tank and the second liquid discharge head, fourth sub-tank configured to store gas and liquid;
• a negative-pressure air tank configured to store gas and supply a negative air pressure;
• and
• a positive-pressure air tank configured to store gas and supply a positive air pressure.