Patent Number: 6,293,144

Title: Method and device for monitoring the consumption of a product, for example a printing ink, using a low-pass filter

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.

Inventors: Froger; Marie-Helene (Chateaugiron, FR), Coudray; Pascal (La Chapelle des Fougeretz, FR), Lorgeoux; Mickael (Rennes, FR)

Assignee: Canon Kabushiki Kaisha

International Classification: B41J 2/175 (20060101); G01F 23/26 (20060101); G01F 23/22 (20060101); G01F 023/00 (); G01F 023/26 (); G08B 021/00 ()

Expiration Date: 09/25/2018