Patent ID: 8132922
Filing Date: 2012-03-13
Classification: B01D,G03B,H04N

Abstract:
1. A filter unit comprising: a feeding shaft around which an unused part of a roll filter is wound; a take-up shaft for taking up the filter from the feeding shaft; a motor for rotating and driving the take-up shaft so as to take up the filter; a filter unit housing for housing the feeding shaft and the take-up shaft and including, between the both shafts, an opening for exposing the filter; rotation detection patterns that rotate in connection with transfer of the filter caused by taking up the filter and are placed at predetermined intervals in a circumferential direction in which the rotation detection patterns rotate; a pattern sensor for detecting rotation of the rotation detection patterns and outputting a detection signal whose amplitude fluctuates in accordance with the predetermined intervals; and a used amount detecting unit for detecting a used amount of the filter based on a correspondence between a period at which the amplitude of the detection signal fluctuates and an amount of the filter taken up by the take-up shaft.