Apparatus and methods usable in connection with dispensing flexible sheet material from a roll

• US 6,710,606 B2
• Filed: 08/05/2002
• Issued: 03/23/2004
• Est. Priority Date: 03/07/2002
• Status: Expired due to Fees

• Current Assignee: Georgia-Pacific Consumer Products LP (KOCH Industries Incorporated)
• Original Assignee: Georgia-Pacific Corporation
• Inventors: Morris, Andrew R.
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Nguyen, Vincent Q.
• Application Number:
  US10/211,301
• Publication Number:
  US 20030169046A1
• Time in Patent Office: 596 Days
• Field of Search: 324/207.12, 324/225, 324/548, 324/658, 324/659, 324/669, 324/677, 324/684, 324/686, 324/613, 242/560.1, 738/623.81
• US Class Current: 324/658
• CPC Class Codes: A47K 10/36 with mechanical dispensing, roll switching or cutting devices
• CPC Class Codes: A47K 10/3612 with drive and pinch rollers
• CPC Class Codes: A47K 10/3625 with electronic control means
• CPC Class Codes: A47K 2010/3668 Detection of the presence of a user
• CPC Class Codes: A47K 2010/3881 with tearing edges having movable parts
• CPC Class Codes: B65H 35/10 from or with devices for breaking partially-cut or perforated webs, e.g. bursters
• CPC Class Codes: H03K 2017/9606 using one electrode only per touch switch
• CPC Class Codes: Y10T 225/12 With preliminary weakening
• CPC Class Codes: Y10T 225/205 With feed-out of predetermined length from work supply
• CPC Class Codes: Y10T 225/209 With feed-out of lead-end to aid initial grasping
• CPC Class Codes: Y10T 225/232 Plural supply sources
• CPC Class Codes: Y10T 225/238 With housing for work supply
• CPC Class Codes: Y10T 225/268 By resiliently engaging package ends or interior of core
• CPC Class Codes: Y10T 225/30 Breaking or tearing apparatus
• CPC Class Codes: Y10T 83/541 Actuation of tool controlled in response to work-sensing means
• CPC Class Codes: Y10T 83/8822 Edge-to-edge of sheet or web [e.g., traveling cutter]
• CPC Class Codes: Y10T 83/889 Tool with either work holder or means to hold work supply
• CPC Class Codes: Y10T 83/896 Rotatable wound package supply

Abstract

A proximity sensor circuit of a powered dispenser for dispensing individual sheet segments from a continuous roll of sheet material includes an antenna, an oscillator circuit and an automatic sensitivity control circuit. The antenna has a baseline stray capacitance. The oscillator circuit is coupled to the antenna and generates an oscillation signal having a predetermined oscillation amplitude corresponding to the baseline stray capacitance of the antenna. Preferably, the oscillator circuit has a Colpitts oscillator-type topography. The oscillation amplitude of the oscillation signal increases in response to an increase in stray capacitance from the baseline stray capacitance of the antenna and decreases in response to a decrease in stray capacitance from the baseline stray capacitance of the antenna. The automatic sensitivity control circuit is coupled to the oscillator circuit and detects a change in the oscillation amplitude of the oscillator signal.

Claims

1. A proximity sensor circuit, comprising:

an antenna having a baseline stray capacitance;

an oscillator circuit coupled to the antenna and generating an oscillation signal having a predetermined oscillation amplitude corresponding to the baseline stray capacitance of the antenna, the oscillation amplitude of the oscillation signal increasing in response to an increase in stray capacitance from the baseline stray capacitance of the antenna and decreasing in response to a decrease in stray capacitance from the baseline stray capacitance of the antenna; and

an automatic sensitivity control circuit coupled to the oscillator circuit and detecting a change in the oscillation amplitude of the oscillator signal, the automatic sensitivity control circuit controlling the amplitude of the oscillator signal to counteract a change in stray capacitance from the baseline stray capacitance of the antenna and maintaining the oscillation amplitude of the oscillator signal at the predetermined oscillation amplitude to provide a substantially constant sensitivity to changes in stray capacitance from the baseline stray capacitance of the antenna.

2. The proximity sensor circuit according to claim 1, wherein the oscillator circuit has a Colpitts oscillator-type topography.

3. The proximity sensor circuit according to claim 2, wherein the automatic sensitivity control circuit controls the amplitude of the oscillator signal by controlling a current in the oscillator circuit.

4. The proximity sensor circuit according to claim 1, wherein a detect signal is generated by the proximity sensor circuit when the automatic sensitivity control circuit detects an increase in the oscillation amplitude of the oscillator signal.

5. The proximity sensor circuit according to claim 4, further comprising a shield coupled to and driven by the oscillator circuit, the shield reducing the baseline stray capacitance of the antenna.

6. The proximity sensor circuit according to claim 5, wherein the shield reduces the baseline stray capacitance an amount that is about two orders of magnitude greater than an increase in stray capacitance sensed by the proximity sensor circuit for generating the detect signal.

7. The proximity sensor circuit according to claim 4, wherein the increase in oscillation amplitude is caused by a hand placed in proximity to the antenna.

8. A method for providing substantially constant sensitivity for sensing changes in a baseline stray capacitance to an antenna, the method comprising steps of:

generating an oscillation signal coupled to the antenna and having a predetermined oscillation amplitude corresponding to the baseline stray capacitance of the antenna, the oscillation amplitude of the oscillation signal increasing in response to an increase in stray capacitance from the baseline stray capacitance of the antenna and decreasing in response to a decrease in stray capacitance from the baseline stray capacitance of the antenna;

detecting a change in the oscillation amplitude of the oscillator signal;

controlling the amplitude of the oscillator signal to counteract the detected change in stray capacitance from the baseline stray capacitance of the antenna; and

maintaining the oscillation amplitude of the oscillator signal at the predetermined oscillation amplitude to provide a substantially constant sensitivity to changes in stray capacitance from the baseline stray capacitance of the antenna.

9. The method according to claim 8, wherein the step of generating the oscillation signal is performed by an oscillator circuit having a Colpitts oscillator-type topography.

10. The method according to claim 9, wherein the step of controlling the amplitude of the oscillator signal includes a step of controlling a current in the oscillator circuit.

11. The method according to claim 9, wherein the step of detecting a change in the oscillation amplitude of the oscillator signal includes a step of generating a detect signal when an increase in the oscillation amplitude is detected.

12. The method according to claim 11, wherein the oscillator circuit includes a shield, the method further comprising a step of driving a shield with a signal related to the oscillation signal for reducing the baseline stray capacitance of the antenna.

13. The method according to claim 12, wherein the shield reduces the baseline stray capacitance an amount that is about two orders of magnitude greater than an increase in stray capacitance that generates the detect signal.

14. The method according to claim 11, wherein the increase in oscillation amplitude is caused by a hand placed in proximity to the antenna.