Floor cleaning device

1. A liquid containing system for a floor cleaning device, the liquid containing system comprising:

a first reservoir adapted to contain liquid; and

a second reservoir, smaller than the first reservoir, wherein the second reservoir is provided with at least one liquid and air-tight inlet connection on a top surface thereof, wherein the second reservoir comprises a replaceable reservoir adapted to be replaceably coupled, at the top surface of the second reservoir, to a bottom surface of the first reservoir via the at least one liquid and air-tight inlet connection to facilitate a flow of the liquid from the first reservoir into the second reservoir, the second reservoir further having a bottom surface provided with an outlet having a plurality of openings to allow the liquid in the second reservoir to be extracted by means of capillary force in response to a mopping substrate being mounted against the plurality of openings, wherein responsive to the second reservoir being coupled to the first reservoir, the first reservoir and second reservoir together are substantially closed but for the plurality of openings, wherein a diameter of the openings comprises a diameter selected from the group consisting of (i) in a range of 0.2 to 0.9 mm, (ii) in a range of 0.2 to 0.4 mm, and (iii) 0.3 mm, and wherein the outlet comprises first openings arranged to be in direct contact with a mopping substrate, and at least one second opening operative as an air vent which is at a height elevation raised in comparison with an elevation of the first openings.

2. A liquid containing system as claimed in claim 1 , wherein the at least one liquid and air-tight inlet connection comprises a single connection, centrally located on the top surface of the second reservoir, for being connected at a corresponding location of the bottom surface of the first reservoir.

3. A liquid containing system as claimed in claim 1 , wherein the at least one liquid and air-tight inlet connection comprises two connections, each connection being located on the top surface of the second reservoir at opposite ends thereof, for being connected at a corresponding location of the bottom surface of the first reservoir.

4. A liquid containing system as claimed in claim 1 , wherein the second reservoir is one selected from a plurality of different second reservoirs having dimensions of evenly spaced openings different among corresponding openings of individual ones of the plurality of different second reservoirs or a number of openings different from among a number of openings of respective individual ones of the plurality of different second reservoirs, further wherein at least one of the different second reservoirs being connected to the first reservoir via at least one liquid and air-tight connection that can be opened or closed.

5. A liquid containing system as claimed in claim 1 , wherein the at least one liquid and air-tight connection between the second reservoir (R 2 ) and the first reservoir (R) has a diameter that is at least 6 mm.

6. A liquid containing system as claimed in claim 1 , wherein the liquid containing system further comprises a flexible membrane coupled to the first reservoir, wherein the flexible membrane is operable as a movable part that can be operated to obtain a volume reduction within a volume of the first reservoir of the liquid containing system.

7. A liquid containing system as claimed in claim 1 , further comprising an air valve adapted to open in response to an under-pressure in the first and second reservoirs of the liquid containing system exceeding a first threshold, and adapted to close in response to the under-pressure falling below a second threshold.

8. A liquid containing system as claimed in claim 1 , further comprising a mopping substrate, wherein the mopping substrate has a mass per surface area selected from the group consisting of (i) lower than 2.3 kg/m 2 , (ii) in a range of 0.2 to 1.5 kg/m 2 , and (iii) in a range of 0.65-1.1 kg/m 2 .

9. A liquid containing system as claimed in claim 1 , further comprising a mopping substrate provided with fibers, each fiber having a fiber diameter selected from the group consisting of (i) in a range of 2-9 μm, (ii) in a range of 2-6 μm, and (iii) in a range between 3-4 μm.

10. A liquid containing system as claimed in claim 1 , wherein the plurality of openings comprise etched openings in a strip having a thickness selected from the group consisting of (i) in a range of 0.05 to 1 mm, and (ii) in a range of 0.1 to 0.2 mm.

11. A floor cleaning device comprising a liquid containing system as claimed in claim 1 .