Dispenser for liquid crystal display panel and method for controlling gap between substrate and nozzle using the same
A dispenser for a liquid crystal display panel includes a syringe having a nozzle provided at an end thereof, a body in which the syringe is mounted, a vertical driving stepping motor for moving the body in a vertical direction, a first sensor for detecting whether the nozzle of the syringe is in contact with a substrate, a second sensor for detecting a gap distance between the nozzle and the substrate, and a main unit for controlling the vertical driving stepping motor in response to an output from the second sensor to obtain a desired gap distance between the nozzle and the substrate.
1. A method for controlling a gap between a nozzle and a substrate using a dispenser for a liquid crystal display panel, comprising:
loading a substrate onto a metallic table;
lowering a body with a syringe mounted therein using a vertical driving stepping motor;
detecting whether a nozzle of the syringe is in contact with the substrate using a first sensor, wherein the first sensor is a magnetic sensor;
sending an electric signal from the first sensor to a control unit, wherein the electric signal changes as the body is lowered by the vertical driving stepping motor toward the table;
recognizing an absence of change in the electric signal by the control unit as the nozzle being in contact with the substrate;
raising the body;
detecting a gap distance between the nozzle and the substrate using a second sensor; and
controlling the vertical driving stepping motor so that a desired gap distance is obtained between the nozzle and the substrate.
2. The method of claim 1 , wherein controlling the vertical driving stepping motor includes obtaining the desired gap distance of about 40 μm.
3. The method of claim 1 , further comprising repositioning the body above the substrate while maintaining the desired gap distance between the body and the substrate.
4. The method of claim 1 , wherein raising the body includes raising the body when the nozzle is detected to be in contact with the substrate.
5. The method of claim 1 , wherein detecting the gap distance between the nozzle and the substrate includes:
irradiating light from a light emitting unit mounted on the body onto the substrate;
receiving a reflected light from the substrate using a light receiving unit mounted on the body; and
determining the gap distance according to a position on a surface of the light receiving unit when the reflected light is incident and received.
6. The method of claim 1 , wherein when the nozzle is in contact with the substrate, the lowering of the body stops so that the electric signal stops changing.
7. The method of claim 6 , wherein when the control unit recognizes that the lowering of the body has stopped, the control unit stops driving the vertical driving stepping motor.