Method and device for monitoring the consumption of a product, for example a printing ink, using a low-pass filter
US6293144A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 25, 1998 |
| Grant date | Sep 25, 2001 |
| Priority date | — |
| Expiry date | Jun 25, 2018 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41J2/17566
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In order to monitor the consumption of a normally electrically conductive product contained in a storage chamber of a reservoir made of electrically non-conductive material, the storage chamber is disposed in a capacitive arrangement and a measurement procedure is defined, according to which, in response to an excitation signal applied to the capacitive arrangement, a measurement signal is obtained (at 122), one characteristic of which has an amplitude which varies substantially with the quantity of product contained in the storage chamber. Before deducing the value of information representing the quantity of product available in the reservoir from this amplitude, the measurement signal has filtering applied to it, according to which it is multiplied by a reference signal of frequency at least approximately equal to that of the excitation signal (at 121) and the multiplied signal is applied to a low-pass filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.