Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Reexamination Certificate
1998-06-02
2001-08-14
Lee, Cheukfan (Department: 2722)
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
C358S475000, C358S497000
Reexamination Certificate
active
06275307
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image read apparatus for converting characters or images into read digital data. More particularly, this invention relates to an image read apparatus consisting of a linear image sensor and a vertical scanning mechanism, enabling two-dimensional image to be obtained while synthesizing sub-images.
DESCRIPTION OF THE PRIOR ART
Formerly, an image read apparatus is generally constituted by way of a read apparatus of the two-dimensional image data. A two-dimensional image sensor or a linear image sensor is in use for the image read apparatus by way of an image read sensor.
A general two-dimensional image sensor has on the order of three hundreds of thousands to eight hundreds of thousands of pixels. In contrast thereto, the image which is read by a linear image sensor has more than two thousand×3000 pixels. Consequently, the number of pixels of the two-dimensional image sensor is lower than that of the linear image sensor, with the result that there is the problem that resolution of the two-dimensional image sensor is insufficient.
When the linear image sensor is in use as by way of image-electric signal conversion element, an image read apparatus which reads in a two-dimensional image is constituted, while combining the linear image sensor with operation of vertical scanning. The image read apparatus of this constitution is separated into three kinds of types such as a flat bed type causing a box type apparatus to turn manuscript side to read in, a hand-held type in which the user implements vertical scanning by moving the device on the manuscript, or an indirect type image scanner in which the manuscript face is away from a read unit provided with a linear image sensor.
By way of examples, of indirect type image scanner whose read unit is separated from the manuscript surface, one is Form [DS-3000] made by CHINON INDUSTRIES INC. the other is a trademark [OOBAN SOKUSHA] made by Casio Computer, Co., Ltd. In the case of the image scanner which reads an image data in an indirect type manner, brightness should be supplied by a ceiling light, natural light, or an auxiliary light source. In the image scanner devices of both CHINON INDUSTRIES INC. and Casio Computer, Co., Ltd. the light is supplied by only the ceiling light instead of an auxiliary light source.
By way of example of the indirect type image scanner using an exclusive auxiliary light source, there is the “image read apparatus” of Japanese Patent Application Laid-Open No. HEI 06-137035 of the conventional example 1. In conventional example 1, an image scanner unit is combined with a table lamp so that brightness is supplied with the table lamp as the exclusive auxiliary light source. However, in the indirect type image scanner, regardless of the auxiliary light source used, it is normal that light of a ceiling lamp is deflected into the scanner unless the ceiling lamp light is shaded. As reading time makes high speed, flicker of the lamp line AC flowing into the ceiling lamp causes the generation of stripe lines in the line direction of the linear image sensor, thus affecting the read image.
By way of method for reducing bad influence according to the above described ceiling light, “image read apparatus” of the Japanese Patent Application Laid-Open No. HEI 07-308748 of the convention example 2 proposes method for implementing correction to the image. In this method, variation of brightness of the ceiling lamp caused by lamp line AC is taken out by way of output signal. There is provided a different optical sensor from the linear image sensor, which optical sensor causes the above described output signal to invert to add to the image signal.
Further, the Japanese Patent Application Laid-Open No. HEI 07-336586 discloses a method for removing the influence of the flicker. In this method, a signal detected due to an illumination light detecting means of the light source is analyzed, before setting exposed time corresponding to frequency component to a line sensor, so that the influence of the flicker is removed.
Furthermore, by way of the method for removing variation component followed by brightness variation among the image signal instead of provision of another sensor, “image information processing apparatus” of the Japanese Patent Publication No. HEI 01-19311 by Canon Inc. is disclosed by way of the conventional example 4. In example 4 a prescribed width in the direction of vertical scanning is read while moving a light receiving element group (semi-multi sensor) arranged in such a way that several ten pixels are arranged in the vertical scanning direction and in the horizontal scanning direction. The manuscript being scanned is then shifted in the vertical scanning direction of width corresponding to the read width, again the semi-multi sensor is moved in the horizontal scanning direction repeatedly. This method enables a manuscript of two-dimensions to be read.
With respect to removing a variation component accompanying a brightness variation, there is provided a reference member for quantity of light in front of the manuscript image, causing the image of the reference member to read to the part of pixel among a plurality of pixels of the semi-multi sensors, thus obtaining illuminating information by using a peak hold circuit. An automatic gain control circuit (AGC) causes correction to the image signal such that first illuminating information agrees with the following illuminating information. Alternatively, there is provided a switch to switch signal outputting period of the illuminating information to the period of image signal, thus implementing correction to the image signal by means of a comparator.
In “line sensor camera” disclosed in the Japanese Patent Application No. HEI 07-203286 by Hitachi Denshi, Co., Ltd. by way of the conventional example 5, a line image sensor is used as an image pick-up device, and a part of the line image sensor is directly used as a sensor for detecting flicker. The outputted signal for detecting flicker is subjected to sample-hold to be inverted, before being added to an amplification circuit of the image signal, thus implementing an inverse correction.
In “imaging device” of the Japanese Patent Application No. HEI 06-325194 by DENSO CORPORATION LTD. by way of the conventional example 6, the imaging device divides pulsating cycle of illumination into a plurality of cycles, thus accumulating light received electric charges corresponding to the numbers of division, before outputting by way of the image signal, so that pulsating variation of the illumination is absorbed. By way of example in which addition of electric charge instead of accumulation of electric charge causes a plurality of imaging result to be processed, “imaging device” is disclosed in the Japanese Patent Application Laid-Open No. HEI 07-298129 by Canon Inc. by way of the conventional example 7. The imaging device causes the flicker component of the light source to be removed by adjusting the plurality of imaging results while combining the adder with the delay circuit in terms of the image signal.
The above-described respective conventional examples are the examples in which light receiving elements by way of imaging element are disposed in line configuration (i.e., one-dimension). However, in the image input apparatus using two-dimensional image sensor (area CCD) in which light receiving elements are disposed in two-dimensional configuration, flicker to be variation of light of disturbance is a problem. By way of method for resolving the problems, the Japanese Patent Application Laid-Open No. HEI 08-246971 of the conventional example 8 discloses “luminous exposure control method of imaging device” which causes exposed time to determine such that imaging reference cycles comes into the least common multiple of light-emitting cycle, or the imaging reference cycle comes into integer number times of cycle, so that is enables flicker generated due to brightness cycle of the light source to be removed. Further, in the “image processing a
Lee Cheukfan
NEC Corporation
Scully Scott Murphy & Presser
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