DETECTING APPARATUS FOR DETECTING MOISTURE CONTENT OF MEDIA STACK

Abstract

A detecting apparatus for detecting information of at least a portion of a stack of sheet media includes an illuminating unit and a detecting unit. The illuminating unit illuminates a side of the stack of sheet media, or a portion thereof with electromagnetic waves. The detecting unit detects electromagnetic waves transmitted through or reflected by the stack of sheet media, or a portion thereof. The detecting apparatus is adapted to compare information of the electromagnetic waves detected by the detecting unit with information about attenuation of electromagnetic waves due to moisture contained in the sheet medium, and detect information of the moisture content of at least a portion of the stack of sheet media.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a first embodiment of a detecting apparatus according to the present invention, which detects moisture content of at least a portion of a paper stack by using EM waves.

FIG. 2 is a side view, viewed from a side of an EMW generator, illustrating a paper tray for holding a paper stack in FIG. 1.

FIG. 3 is a graph showing exemplified calibration curves representing relationships between moisture content of paper, transmission distance of EM waves through paper, and detected maximum amplitude.

FIG. 4 is a top view illustrating a transmission manner of EM waves through measurement media (papers) in a modification of the first embodiment.

FIG. 5 is a top view illustrating a transmission manner of EM waves through measurement media (papers) in another modification of the first embodiment, using plural beams of EM waves.

FIG. 6 is a schematic view illustrating a second embodiment of a detecting apparatus according to the present invention, which detects a distribution of moisture content in a stacking direction of a paper stack by using EM waves.

FIG. 7 is a schematic top view illustrating a third embodiment of a detecting apparatus according to the present invention, which detects a distribution of moisture content in an in-plane direction of a paper stack by using EM waves.

FIG. 8 is a side view, viewed from a side of an EMW generator, illustrating a paper tray for holding a paper stack in FIG. 7.

Claims

1. A detecting apparatus for detecting moisture content of at least a portion of a stack of sheet media, the detecting apparatus comprising: an illuminating unit for illuminating a side of at least a portion of the stack of sheet media with electromagnetic waves;a detecting unit for detecting electromagnetic waves transmitted through or reflected by at least a portion of the stack of sheet media;a memory for storing information about attenuation of electromagnetic waves due to moisture contained in a sheet material; anda comparer for comparing information of the electromagnetic waves detected by the detecting unit with the information in the memory about attenuation of electromagnetic waves due to moisture contained in the sheet medium, and determining moisture content of at least a portion of the stack of sheet media.

2. The detecting apparatus according to claim 1, wherein the information stored in the memory is stored calibration curves, and a maximum amplitude of the transmitted or reflected electromagnetic waves detected by the detecting unit is compared with the stored calibration curves.

3. The detecting apparatus according to claim 2, wherein the calibration curves are composed of three parameters; transmission distance of the electromagnetic waves through at least a portion of the stack of sheet media, maximum amplitude of the transmitted or reflected electromagnetic waves detected by the detecting unit, and moisture content of the sheet medium.

4. The detecting apparatus according to claim 1, wherein a plurality of sets of illuminating units and detecting units are provided to detect electromagnetic waves transmitted through or reflected by at least a portion of the stack of sheet media, respectively.

5. The detecting apparatus according to claim 1, wherein the illuminating unit and detecting unit are each movable in a vertical direction along a side of the stack of sheet media to detect information of a distribution of moisture content of at least a portion of the stack of sheet media along the vertical direction.

6. The detecting apparatus according to claim 1, wherein the illuminating unit and detecting unit are movable in a horizontal direction along a side of the stack of sheet media to detect information of a distribution of moisture content of at least a portion of the stack of sheet media along a direction perpendicular to a stacking direction.

7. The detecting apparatus according to claim 1, wherein the electromagnetic waves contain at least a component at frequency or frequencies in a frequency range between 30 GHz and 30 THz, which can be absorbed by moisture.

8. The detecting apparatus according to claim 1, wherein a spot of the electromagnetic waves is adjusted to have the same size as a side of a region of the stack of sheet media.

9. An image forming apparatus comprising: the detecting apparatus for detecting moisture content of at least a portion of a stack of sheet media, the detecting apparatus comprising:an illuminating unit for illuminating a side of at least a portion of the stack of sheet media with electromagnetic waves;a detecting unit for detecting electromagnetic waves transmitted through or reflected by at least a portion of the stack of sheet media;a memory for storing information about attenuation of electromagnetic waves due to moisture contained in a sheet material; anda comparer for comparing information of the electromagnetic waves detected by the detecting unit with the information in the memory about attenuation of electromagnetic waves due to moisture contained in the sheet medium, and determining moisture content of at least a portion of the stack of sheet media;an image forming unit for forming an image on a record sheet medium; anda controller which controls image forming settings,wherein image forming settings of the image forming unit are adjusted by the controller based on the moisture content of the record sheet medium detected by the detecting apparatus.