Controller for uniform fluid dispensing

A controller for dispensing fluid onto a substrate in a system having a relative movement between the substrate and the dispensing unit, the controller comprising:

• (a) sensing means for sensing the relative movement between the substrate and the dispensing unit and generating a sensor signal reflective of the relative movement;
• (b) regulating means for regulating the flow rate of the fluid to the dispensing unit in response to a control signal;
• and
• (c) operation means, connected to receive the sensor signal, for supplying a control signal to the regulating means, the operation means having storage means for storing the movement signal received from the sensing means in response to a timed control signal and generating an output signal reflective of the movement occurring during the timed signal, time period means for generating a timed control signal to the storage means, so that the movement signal is received for a preselected time, first generating means connected to the output of the storage means for generating a signal reflective of the movement during the preselected time period, comparison means, connected to the first generating means for comparing the rate of relative movement to a preselected signal reflective of a desired maximum flow rate, and second generating means, for generating the control signal supplied to the regulating means reflective of the comparison between the computed rate of movement signal and the preselected flow rate signal so that the flow rate of the fluid dispersed from the dispensing unit varies substantially proportionally to the rate of relative movement between the dispensing unit and the substrate so that the amount of dispensed fluid per unit length of substrate is substantially constant.

A method of controlling the fluid dispensed onto a substrate in a system having relative movement between the substrate and a dispensing unit, comprising the steps of:

• sensing the relative movement;
• generating a signal reflective of the movement;
• computing the rate of movement signal from the movement signal;
• comparing the rate of relative movement to a preselected signal reflective of a desired maximum flow rate;
• generating a signal reflective of the comparison between the computed rate of movement signal and the preselected flow rate signal;
• and
• regulating the rate of supplying fluid to the dispensing unit in response to the comparison signal so that the rate of fluid varies substantially proportionally to the rate of relative movement between the dispensing unit and the substrate so that the amount of dispensed fluid per unit length of substrate is substantially constant.