JPH05167053A - Image sensing element for draft readout use and draft readout method - Google Patents

Abstract

PURPOSE:To remove a moire simply and surely by a method wherein the thickness of cover glasses arranged so as to face individual lines in a two-line CCD line sensor arranged on two parallel lines inside the same package is made different form each other. CONSTITUTION:A photodetection part 100 and a photodetection part 200 are arranged respectively in one line each on a silicon chip 1. A stepped part due to a thickness is formed in an arranged cover glass 2D so as to face the individual lines; the thickness of the cover glass 2D is formed to be thin in a part faced with the line of the photodetection part 100 and to be thick in a part faced with the line of the photodetection part 200. An optical light-path length from an image-forming lens up to the front of the chip 1 is short with reference to the line of the photodetection part 100 and long with reference to the line of the photodetection part 200 due to the difference in the thickness of the cover glass 2D. As a result, a draft image by means of a coupling lens is formed so as to be displaced, and a moire can be removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading image pickup device and a document reading method using the device.

[0002]

2. Description of the Related Art CC in which minute light receiving portions are arranged in one line
A method of reading a document using a D-line sensor has been widely known in the related art for digital copying machines and facsimile machines. In this scanning method, "photo original"
When the original image is reproduced with the signal read from, "moire" is likely to occur.

Conventionally, as a measure for preventing the occurrence of such moiré, two modes of a text original mode and a photo original mode are prepared as image data processing modes based on a read signal, and the image data is filtered in the photo original mode. However, there is a problem that the image data processing becomes complicated because the moire is removed by applying the above.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a novel original reading method capable of easily and reliably removing moire without requiring special image processing, It is an object of the present invention to provide an image pickup device for reading an original used for carrying out this method.

[0005]

The image reading device for reading an original of the present invention is a "two-line CCD line sensor in which minute light receiving portions are arranged in two parallel lines in the same package.
The thickness of the cover glass arranged facing each line is different from each other ”.

The cover glass provided by the minute light receiving portion facing each line may be a single glass plate in common, but "each line is a separate glass plate having a different thickness to absorb light. It is possible to have a structure in which a partition member having a flexible surface is used for partitioning (claim 2). The partition member is preferably formed of "the same material as the package" (claim 3).

When a single glass plate having a step difference in thickness is used for two lines in common, a step part depending on the thickness is formed in a "groove", and the "bottom surface and side surface part" of this groove are treated with a pearlescent material. It is better to "paint and to paint black" (Claim 4).

The original reading method according to the present invention is the fifth aspect.
In the method for reading an original using the above-mentioned original reading image pickup element, as described in "A document reading image obtained by focusing an original image by the same imaging lens only on one line. It is projected on the device.

[0009]

Referring to FIG. 4, reference numeral 1 is a silicon chip, and reference numeral 2 is a cover glass. On the silicon chip 1, minute light receiving portions 100 are arranged in one line in the direction orthogonal to the drawing, and similarly, minute light receiving portions 200 are arranged in one line in the direction orthogonal to the drawing. The received light is converted into a signal for each of the light receiving units 100 and 200.
Therefore, the chip 1 constitutes the central part of the 2-line CCD line sensor.

Light receiving portions 100, 2 formed on the chip 1
Cover glass 2 placed facing each line of 00
Is provided with a "step due to thickness", and the thickness of the cover glass 2 is thin in the portion facing the line of the light receiving unit 100 and thick in the portion facing the line of the light receiving unit 200.

Consider projection of the image of the original document on the front surface of the chip 1 (the surface on which the light receiving portions are arranged) by an imaging lens (not shown) which is assumed on the right side of FIG. At this time, the lens optical axis is assumed to be orthogonal to the front surface of the chip 1.

Then, the optical path length from the imaging lens to the front surface of the chip 1 is short with respect to the line of the light receiving element portion 100 due to the difference in the thickness of the cover glass 2, and the light receiving portion 20.
It becomes longer for the 0 line. Therefore, the original image by the imaging lens cannot be focused on each of the two lines, and when the line of the light receiving unit 100 is focused as shown in FIG. 4, the line of the light receiving unit 200 is focused. As a result, an image is formed at a position displaced from the line to the lens side. Therefore, in this case, the original image is a "focused" image on the line of the light receiving unit 100, but a slightly "out of focus" image on the line of the light receiving unit 200.

By the way, the above-mentioned "moiré" is apt to occur when the original image formed on the line includes an image component of a spatial frequency close to the spatial frequency of the light receiving section array,
Therefore, it can be removed by slightly blurring the focus of the document image and "lowering the spatial frequency of the document image as a whole".

Therefore, in the case of a photographic original in which moiré is likely to occur, the moiré can be prevented by reproducing the image by using the line output signal from the light receiving section 200 as an image signal.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a document reading image pickup device. This embodiment is an embodiment of the device of claims 1, 2 and 3. FIG. 1A shows an image sensor 1 for reading a document.
0 is an external view, and (b) is a sectional view. Document reading element 10
1 uses the same reference numeral as that of the chip 1 in FIG. 4 in order to avoid complication. The chip 1 of the embodiment of FIG. 1 is the same as the chip 1 of FIG. ) Is provided inside the package 3, and the chips 1 are sealed inside the package 3 by providing cover glasses 2A and 2B and a partition member 2C facing the front surface of the chip 1. Reference numeral 4 indicates a pin. The direction of the lines of the light receiving portions 100 and 200 in the chip 1 is the direction orthogonal to the drawing of FIG.

The cover glass 2A provided facing the line of the light receiving section 100 is thin, and the cover glass 2B provided facing the line of the light receiving section 200 is thick. These cover glasses 2A and 2B are partitioned by a thin plate-shaped partition member 2C whose longitudinal direction is the direction of each line.

Referring again to FIG. 4, the cover glass basically has a different thickness as in the cover glass 2 of FIG. 4 if the portions facing each line have different thicknesses. The step portion 2H may be left as it is as shown in the figure. However, when the stepped portion 2H is configured to reflect light, the light reflected by the stepped portion 2H is received by the light receiving portions 100, 20 regardless of whether it is specular reflection or irregular reflection.
It tends to cause noise in the image signal as stray light with respect to zero. Therefore, in the embodiment of FIG. 1, the partition member 2C partitions the cover glasses 2A and 2B, and the surface of the partition member 2C is made to have a light absorbing property (antireflection property).

Since the cover glasses 2A and 2B are fixed to the package 3 with an adhesive, the partition member 2C is also preferably fixed to the bar glasses 2A and 2B with an adhesive. In this case, if the rate of shrinkage due to temperature change is different between the package 3 and the partition member 2C, the adhesive may be peeled off between the cover glass and the package, or between the cover glass and the partition member, or the cover glass may not be desired. There is some stress. In order to avoid such a problem, the partition member 2C is made of the same ceramic material as the package 3,
The rate of expansion and contraction due to temperature change was set to be the same.

FIG. 2 is a sectional view showing another embodiment of the image pickup device for reading a document (embodiment of the device of claim 4). In order to avoid complication, the same symbols as those in FIG. 1 are attached to those which are not considered to be confused.

Image pickup device 10 for reading an original according to the embodiment shown in FIG.
The difference between the image pickup device 10A and the document reading image pickup device 10A of the embodiment shown in FIG. 2 lies in the form of the cover glass. Image sensor 10 for reading originals
The cover glass 2D of A is one glass plate having a step difference in thickness. In order to prevent the generation of stray light in the step portion, a groove 2E is formed in the step portion, and a pear-skin treatment is performed on the bottom surface and the side surface portion of the groove 2E (surface roughening treatment for forming fine unevenness like the surface of a pear) Then, a black paint was applied to the formed pear base portion.

FIG. 3 schematically shows an example of an apparatus for carrying out the method of the fifth aspect. The original 0 to be read is placed flat on the original glass 30 and illuminated and scanned by the lamp 31. The reflected light from the original 0 moves together with the lamp 30 in a predetermined direction (in this example, to the left in FIG. 3) at a predetermined speed: V
Is reflected by a mirror 35 that moves in the same direction, is folded back by a roof mirror 37 that moves in the same direction as the mirror 35 at a speed of V / 2, and is imaged by the imaging lens 39.
0 is projected as an original image. Image sensor 1 for reading originals
0 is the same as that described with reference to FIG.
It is supported by.

The original image formed by the imaging lens 39 is projected while being focused on the line formed by the light receiving section 100 of the original reading image pickup device 10 shown in FIG. Therefore, the signal from the line of the light receiving unit 100 is a signal corresponding to the in-focus original image, and the signal from the line of the light receiving unit 200 is a signal corresponding to the slightly out-of-focus original image. Therefore, when the original 0 is a text original, the signal from the line of the light receiving unit 100 is selected, and when the original 0 is a photographic original, the signal from the line of the light receiving unit 200 is selected to filter the output signal. Even if you do not perform the data processing of
An appropriate reproduced image can be obtained according to the original, and moire can be removed from the reproduced image.

Output signals from the respective lines of the original reading image pickup device 10 are subjected to necessary electrical processing by a control / processing circuit formed on the circuit board 42. In the above description, what has been described as an output signal from each line is a signal after undergoing the electrical processing required by the control / processing circuit. The control and processing circuit also controls the entire reader.

The signal processed by the control processing circuit (the signal from each line is selected according to whether the original is a text original or a photographic original) is sent to an external device such as a copying machine or a display via the interface 44. Is output.

[0025]

As described above, according to the present invention, it is possible to provide a novel document reading image pickup device and a document reading method using the same. Since the present invention is configured as described above,
When the original reading image pickup element of the present invention is used to read the original by the method of the present invention, it is possible to easily and reliably prevent the occurrence of moire in the reproduced image of the photographic original.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of a document reading image pickup device.

FIG. 2 is a diagram for explaining another embodiment of the image sensor for reading a document.

FIG. 3 is a diagram schematically illustrating only an example of an apparatus for performing a document reading method.

FIG. 4 is a diagram for explaining the principle of moiré removal.

[Explanation of symbols]

1 Silicon chip in which minute light receiving parts are arranged in two lines 2A, AB Cover glass 2C Partition member 3 Package 4 pins 100,200 Minute light receiving part

Claims (5)

[Claims] 1. A two-line CCD line sensor in which minute light receiving portions are arranged in two parallel lines in the same package,
An image pickup device for reading an original, characterized in that the cover glasses arranged facing each line have different thicknesses. 2. The cover glass according to claim 1, wherein the cover glasses provided facing the respective lines are separate glass plates having different thicknesses, and are separated from each other by a partition member having a light absorbing surface. An image sensor for reading a document. 3. The image pickup device for reading an original according to claim 2, wherein the partition member is made of the same material as the package. 4. The cover glass according to claim 1, wherein the cover glass provided facing each line is the same glass plate, and a step portion depending on the thickness is formed in the groove, and a bottom surface portion and a side surface portion of the groove are pear-skin texture. Processed, and
An image sensor for reading an original, which is painted in black. 5. A method of reading a document using the document reading image pickup device according to claim 1, 2, 3 or 4, wherein a document image formed by the same imaging lens is used for one line. A method of reading a document, which comprises focusing only on and projecting the image onto a document reading image sensor.