Control system for atomizing liquids with a piezoelectric vibrator

• US 6,439,474 B2
• Filed: 07/17/2001
• Issued: 08/27/2002
• Est. Priority Date: 03/05/1999
• Status: Expired due to Fees

• Current Assignee: SC Johnson & Son Incorporated
• Original Assignee: SC Johnson & Son Incorporated
• Inventors: Denen, Dennis J.
• Primary Examiner(s): Morris, Lesley D.
• Assistant Examiner(s): Hwu, Davis
• Application Number:
  US09/905,953
• Publication Number:
  US 20010050317A1
• Time in Patent Office: 406 Days
• Field of Search: 239/4, 239/102.1, 239/102.2, 239/326, 239/553.3, 239/145, 310/314, 310/315, 310/316, 310/316.01, 310/328
• US Class Current: 239/102.2
• CPC Class Codes: A01M 1/205 using vibrations, e.g. ultrasonic or piezoelectric atomizers
• CPC Class Codes: A61L 9/14 using sprayed or atomised substances including air-liquid contact processes
• CPC Class Codes: B05B 17/0646 Vibrating plates, i.e. plates being directly subjected to the vibrations, e.g. having a piezoelectric transducer attached thereto
• CPC Class Codes: B05B 17/0684 Wicks or the like

Abstract

There is described a battery driven atomizer in which an alternating voltage is applied to a piezoelectric actuation element to cause it to expand and contract and vibrate an atomizing membrane. The alternating voltage is controlled to produce a high amplitude vibration during a first portion of a drive period, to initiate atomization, and thereafter to produce a lower amplitude vibration to sustain atomization during the remainder of the drive period. The frequency of the alternating voltage is swept repeatedly during each drive period.

Claims

1. A drive circuit for a liquid atomizer in which a piezoelectric actuator is coupled to an orifice plate to vibrate the plate to atomize a liquid being supplied to one side of said plate, said drive circuit comprising:

a pair of terminals across which a voltage is applied, and between which said piezoelectric actuator is connected;

an electronic switch also connected between said terminals in parallel with said piezoelectric actuator, said electronic switch being switchable between conducting and non-conducting states;

a switch operating circuit connected to switch said electronic switch between said conducting and non-conducting states; and

a coil connected in series with said piezoelectric actuator between said terminals.

2. A drive circuit according to claim 1, wherein said switch is a field effect transistor.

3. A drive circuit according to claim 1, wherein said switch is connected in parallel with a portion of said coil and said piezoelectric actuator.

4. A drive circuit according to claim 1, wherein said switch operating circuit comprises an oscillator.

5. A drive circuit according to claim 1, wherein said coil is an autotransformer and wherein said electronic switch is connected to a point along said autotransformer.