Liquid droplet transport apparatus
A liquid droplet transport apparatus, which is provided on a nozzle plate of an ink-jet head, including a first electrode and a second electrode which are arranged on a lower surface of the nozzle plate, a driver which applies electric potentials to the first electrode and the second electrode respectively, a resistor layer which is arranged on the lower surface of the nozzle plate and which makes electric conduction to both of the first electrode and the second electrode, and an insulating layer which covers the first electrode, the second electrode, and the resistor layer. Accordingly, the liquid droplet transport apparatus is provided, which makes it possible to transport liquid droplets over a long distance, while simplifying the arrangement for the liquid droplet transport.
1. A liquid droplet transport apparatus which transports a conductive liquid droplet, the liquid droplet transport apparatus comprising:
a substrate;
a first electrode and a second electrode which are arranged on a surface of the substrate;
an electric potential-applying mechanism which applies electric potentials to the first electrode and the second electrode respectively;
a resistor layer which is arranged on the surface of the substrate so that the resistor layer makes contact with both of the first electrode and the second electrode, and the resistor layer, makes electric conduction to both of the first electrode and the second electrode, and which causes an electric potential drop between the first and second electrodes when the electric potentials applied to the first electrode and the second electrode by the electric potential-applying mechanism are different; and
an insulating layer which covers the first electrode, the second electrode, and the resistor layer, wherein the liquid repellence of an surface of the insulating layer on which the liquid droplet is placed is lowered as an electric potential difference is increased between the surface of the insulating layer and corresponding one of the first and second electrodes and the resistor layer covered with the insulating layer.
2. The liquid droplet transport apparatus according to claim 1 , wherein the resistor layer is arranged in an area between the first electrode and the second electrode on the substrate surface.
3. The liquid droplet transport apparatus according to claim 2 , wherein the first electrode and the second electrode extend in parallel to each other on the substrate surface.
4. The liquid droplet transport apparatus according to claim 1 , wherein the first electrode, the second electrode, and the resistor layer are formed of a same conductive material; and a thickness of the resistor layer is smaller than thickness of each of the first electrode and the second electrode.
5. The liquid droplet transport apparatus according to claim 1 , wherein the electric potential-applying mechanism applies a predetermined electric potential to the second electrode such that an electric potential difference between the second electrode and the liquid droplet is greater than an electric potential difference between the first electrode and the liquid droplet; and
a liquid-attractive area, in which liquid repellence is always lower than that of the surface of the insulating layer, is provided in a surrounding area of the substrate surface around the second electrode, the surrounding area being not covered with the insulating layer.
6. The liquid droplet transport apparatus according to claim 1 , wherein the electric potential-applying mechanism is capable of switching two modes of:
a waiting mode in which the electric potentials applied to the first electrode and the second electrode are same; and a liquid droplet transport mode in which the electric potentials applied to the first electrode and the second electrode made to be different so as to move the liquid droplet along the resistor layer.
7. The liquid droplet transport apparatus according to claim 1 , wherein the second electrode has a plurality of individual electrodes;
the individual electrodes are aligned with a spacing distance on the substrate surface; and
adjoining individual electrodes among the individual electrodes are connected to each other via the resistor layer.
8. The liquid droplet transport apparatus according to claim 1 , wherein the liquid droplet transport apparatus is provided in a liquid droplet discharge apparatus which discharges the liquid droplet from a predetermined discharge port;
the discharge port of the liquid droplet discharge apparatus is arranged on the surface of the substrate;
the first electrode is provided on the surface of the substrate at a surrounding position around the discharge port, and the second electrode is provided on the substrate surface at a position separated and away from the discharge port with respect to the first electrode;
the resistor layer makes electric conduction to both of the first electrode and the second electrode; and
the electric potential-applying mechanism applies a predetermined electric potential to the second electrode such that an electric potential difference between the second electrode and the liquid droplet is greater than an electric potential difference between the first electrode and the liquid droplet, and the liquid droplet, which is adhered to surroundings of the discharge port, is transported from the first electrode to the second electrode on the resistor layer.
9. The liquid droplet transport apparatus according to claim 1 , further comprising:
a liquid chamber which is provided on the surface of the substrate and an outlet port which guides the liquid droplet from the liquid chamber to transport the liquid droplet guided from the liquid chamber on the surface of the substrate, wherein the first electrode is provided in the vicinity of the outlet port on the surface of the substrate, and the second electrode is provided separately away from the outlet port with respect to the first electrode on the substrate surface;
the electric potential-applying mechanism applies, to the first electrode, an electric potential different from an electric potential of the liquid contained in the liquid chamber to guide the liquid droplet from the liquid chamber; and
the electric potential-applying mechanism applies a predetermined electric potential to the second electrode such that an electric potential difference between the second electrode and the liquid droplet is greater than an electric potential difference between the first electrode and the liquid droplet, and that the liquid droplet which is guided from the liquid chamber is transported from the first electrode to the second electrode on the resistor layer.
10. The liquid droplet transport apparatus according to claim 9 , wherein a period of time, during which the electric potential-applying mechanism applies the electric potential different from the electric potential of the liquid to the first electrode, is adjusted to change a size of the liquid droplet to be guided from the liquid chamber.
11. The liquid droplet transport apparatus according to claim 10 , wherein the outlet port includes a plurality of individual outlet ports;
a plurality of individual flow passages, which are branched from the liquid chamber, are formed on the substrate, each of the individual outlet ports being provided at one end of one of the individual flow passages;
the first and second electrodes includes a plurality of first and second individual electrodes, respectively, each of the first individual electrodes and each of the second individual electrodes being arranged in one of the individual flow passages; and
the electric potential-applying mechanism applies the electric potentials independently to each of the first and second individual electrodes.
12. The liquid droplet transport apparatus according to claim 11 , wherein each of the first individual electrodes is formed at a boundary of one of the individual flow passages with respect to the liquid chamber; and
each of the second individual electrodes is formed in the vicinity of one of the individual outlet ports of one of the individual flow passages.
13. The liquid droplet transport apparatus according to claim 1 , wherein the resistor layer is formed of a material selected from the group consisting of graphite, carbon, high purity carbon/pyrolytic boron nitride, aluminum nitride, and tungsten.
14. The liquid droplet transport apparatus according to claim 1 , wherein the insulating layer is formed of a fluorine-based resin.
15. The liquid droplet transport apparatus according to claim 1 , wherein the electrical potential-applying mechanism applies a predetermined electric potential to the second electrode so that an electric potential difference between the second electrode and the liquid droplet is greater than an electric potential difference between the first electrode and the liquid droplet, in order to transfer the liquid droplet in a direction from the first electrode toward the second electrode.