Fluid level sensing method and apparatus
AssigneeMicron Technology, Inc.
InventorScott E. Moore
Life of this patent
Estimating the term…
Abstract
A fluid level sensor is provided in a fluid dispensing system, primarily in a photoresist dispensing system used in a semiconductor manufacturing process. A bubble is introduced into the fluid shortly before fluid supply is emptied, said bubble being used to detect a low fluid level. The invention uses a snap-on combination cap and pickup tube, the pickup tube having a small hole near its lower tip, and the cap containing an optical bubble detector.
Claims10
Apparatus to sense a predetermined level of a fluid being dispensed from a bottle means by a pump, comprising:
- (a) a substantially vertical pickup tube within said bottle means, having a bubble hole located at a preselected point along its length at a corresponding elevation to the predetermined level to be sensed, said pickup tube having a first end immersed in the fluid, so that as said fluid is being pumped out of said bottle means through said pickup tube, said fluid level moves along the outside of said pickup tube and passes said bubble hole, said bubble hole then introducing a bubble into said pickup tube;
- and
- (b) bubble detection means mounted within said bottle means and at a second end of said pickup tube, to detect said bubble and hence said predetermined level.
A method to sense a predetermined level of a fluid being dispensed from a bottle means by a pump, comprising the steps of:
- (a) providing a substantially vertical pickup tube within said bottle means, having a first end in fluid communication with said pump and having a bubble hole located along its length at a corresponding elevation to the predetermined level to be sensed, said pickup tube having a second end immersed in the fluid, so that when said fluid level moves along the outside of said pickup tube and passes said bubble hole as said fluid is being pumped out through said pickup tube, said bubble hole introduces a bubble into said pickup tube;
- (b) providing bubble detection means at said first end of said pickup tube;
- and
- (c) while dispensing, detecting said bubble and hence said predetermined level.
Dependencies are inferred from the claim text.