Facsimile and static presentation processing – Facsimile – Picture signal generator
Utility Patent
1994-07-14
2001-01-02
Nguyen, Madeleine (Department: 2722)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S406000, C358S509000
Utility Patent
active
06169612
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a document processor such as an electrostatic copying machine, a facsimile or a document reader, and more specifically to a document processor provided with document detecting means which detects the existing region of a document that is placed on a transparent plate.
DESCRIPTION OF THE PRIOR ART
As is well known, a document processor put into practical use comprises a transparent plate on which a document is placed, a document covering means which covers the document placed on the transparent plate, a document illumination source which illuminates the document placed on the transparent plate, and an image sensor which receives the light irregularly reflected from the document that is illuminated by the document illumination source. The document covering means is constituted by an ordinary document covering member or by a portion of the document carrier means which brings the document onto the transparent plate and then carries it out from the transparent plate. The above document cover is usually disposed to freely swing between a closed position at which it covers the transparent plate and the document placed thereon and an open position at which it permits the transparent plate to be exposed. For scanning the document, the document illumination source moves relative to the document that is placed on the transparent plate. The image sensor is conveniently constituted by a CCD that has a number of elements arranged in a predetermined direction. In the case of a color image processor, there can be used a CCD that includes an R element for receiving red light, a G element for receiving green light and a B element for receiving blue (or violet) light.
Japanese Laid-Open Patent Publication Nos. 68728/1984 and 41842/1988 disclose an image processor of the above-mentioned form which is provided with a document detecting means which detects a document-existing region (i.e. detects the region on which a document is placed on the transparent plate and the size of the said document) on the basis of output signals from the image sensor. According to the image processors disclosed in the above publications, the document covering surface of the document covering means has a mirror surface or a half-mirror surface having a regular reflectance of 60 to 90% in order to discriminate between a document-existing region, i.e., a region where the document exists on the transparent plate, and a no document-existing region, i.e. a region where there exists no document, and in consequence, the document covering surface of the document cover is illuminated through the transparent plate, based on the output signals from the image sensor.
When the document covering surface of the document cover is made to have a mirror surface or a half-mirror surface, the light is irregularly reflected in very small amounts by the document covering surface, and the image sensor receives the irregularly reflected light in small amounts. On the other hand, the surface of the ordinary document usually has a considerably small regular reflectance. Hence, the surface irregularly reflects the light in considerable amount, and so the image sensor receives the irregularly reflected light in considerable amount. Therefore, the document detecting means can detect the document-existing region on the basis of the output signals from the image sensor that change in proportion to the intensity of the received light.
The surface of the ordinary document usually has a considerably small light absorption, and a considerable amount of the light that is irradiated is reflected regularly or irregularly. However, when the document is a copied document, the document often contains so-called solid portions, which are black all over, at the end edges or side edges thereof. The solid portions have a very high light absorption; i.e., only very little light is reflected by the portions which are black all over, and very little light is irregularly reflected, just like the case of the document covering surface having a mirror surface or a half-mirror surface. Also, when the document is an ordinary photograph that has a slightly high regular reflectance, if the photograph contains a dark color portion in the background of the subject, the irregular reflection light is very small because of reduction of irregular reflection light due to regular reflection and absorption of light by the dark color portion. This fact causes the conventional image processor to erroneously discriminate the solid portions of the document or the photographic document as being the document covering surface (i.e. the no document-existing region) of the document covering means.
SUMMARY OF THE INVENTION
The main technical assignment of the present invention is to provide an improved image processor which is capable of detecting the document as desired without erroneously discriminating the document from the document covering surface of the document covering means, i.e. from the region where there exists no document, regardless of whether the document contains portions that are “black all over” or whether the document is a photograph.
Another technical assignment of the present invention is to provide an improved image processor which, though not satisfactorily, is capable of detecting the document even when the image processor is operated without location of the document covering means at the closed position at which it should cover the transparent plate and the document that is placed on the transparent plate. (In this case, however, there remains the probability that a solid portion of the document might be erroneously discriminated to be the region where there exists no document, like with the conventional image processors).
In order to achieve the above-mentioned main technical assignment according to the present invention, the document cover has a document covering surface which has a regular reflectance of from 1.5 to 40% and gives a relative intensity of irregular reflectance light as received by the image sensor of from N2.5 to N8.5 in terms of lightness in the Munsell color system.
In order to achieve the above-mentioned other technical assignment according to the present invention, whether there exists a document on the region or not is discriminated in a different manner depending upon whether the document covering means is at the closed position at which it covers the transparent plate and the document placed thereon or whether the document covering means is at the open position at which it permits the transparent plate and the document placed thereon to be exposed.
That is, in order to achieve the above-mentioned main technical assignment according to the present invention, there is provided an image processor comprising a transparent plate on which a document is placed, a document cover which covers the document placed on the transparent plate, a document illumination source which moves relative to the document that is placed on the transparent plate, an image sensor which receives the light irregularly reflected from the document that is illuminated by the document illumination source, and a document detecting means which detects the document-existing region based on an output signal from the image sensor, wherein a document covering surface of the document cover has a regular reflection factor of from 1.5 to 40% and gives a relative intensity of irregularly reflected light as received by the image sensor of from N2.5 to N8.5 in terms of lightness in the Munsell color system.
In order to achieve the above-mentioned other technical assignment according to the present invention, there is provided an image processor comprising a transparent plate on which a document is placed, a document cover which is disposed to freely move between a closed position at which it covers the transparent plate and the document placed thereon and an open position at which it permits the transparent plate to be exposed, a document covering means detecting means which detects whether the document cover is located at the closed
Antonelli Terry Stout & Kraus LLP
Kyocera Mita Corporation
Nguyen Madeleine
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