JP2000261619A - Image reader and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read the image of an overall original face with high density, while using a line sensor with general reading density by moving and scanning the original face in a direction vertical to the longitudinal direction of the line sensor in a set speed and time. SOLUTION: An image forming lens and line sensor shift amount setting circuit 14 sets shift amounts to be shifted to the longitudinal direction of a line sensor, by integrating a zoom lens and the line sensor according to lens magnification set by a lens magnification setting circuit 12. A scanning speed/ scanning time setting circuit 16 sets a scanning speed and a scanning time in the longitudinal direction of the original face according to the lens magnification set by the lens magnification setting circuit 12. After these setting is ended, an image reading mechanism 17 is operated, and an image in the prescribed region of the original face is read. Image reading is operated two times at different positions, and the read two image data are combined by an image compositing circuit 19 so that the whole original face can be restored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus and method capable of arbitrarily changing the reading density of a document surface.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers, image capture by an image scanner has become popular. Furthermore, the image quality of displays and printers has been improved, and accordingly, image scanners of higher image quality have been desired. For this purpose, it is necessary to increase the density of line sensors generally used in image scanners, but this is very difficult at present from the viewpoint of technology or cost.

On the other hand, for partial reading, it has been proposed to improve the quality of a read image at the time of enlargement by changing the magnification of an imaging lens. As an example of this, a method in which the reading range can be set arbitrarily is described in Japanese Patent Application Laid-Open No.
No. 60 is disclosed.

[0004]

However, if the magnification of the imaging lens is increased to improve the image quality of the read image, the magnification of the imaging lens is increased as it is.
There is a problem that the reading range becomes narrow. That is, there is a problem that partial reading is performed as described above.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus and method capable of reading an image on the entire surface of a document at a high density while using a line sensor having a conventional reading density.

[0006]

An image reading apparatus according to the present invention which solves the above-mentioned problems, scans a document surface to be read while moving the original surface relatively in a direction perpendicular to the length direction of the line sensor. A signal light from the document surface is imaged on the line sensor by an image forming lens having a variable power function, and an image reading apparatus for reading an image on the document surface reads the image for inputting a desired reading density. Density input means, lens magnification setting means for setting the magnification of the imaging lens according to the reading density input from the reading density input means, and the imaging lens to the magnification set by the lens magnification setting means The reading range of the original surface is adjusted in the direction parallel to the length direction of the line sensor according to the magnification set by the imaging lens changing unit that changes the magnification and the lens magnification setting unit. Shift amount setting means for setting a shift amount to be shifted in a predetermined manner, and the reading range of the document surface is relatively shifted in a direction parallel to the length direction of the line sensor by the shift amount set by the shift amount setting means. The speed and the time of scanning by moving the original surface relative to the length direction of the line sensor in a direction perpendicular to the length direction of the line sensor according to a shift means for shifting and a magnification set by the lens magnification setting means, respectively. A scanning speed / scanning time setting unit to be set, the line sensor and the imaging lens, and the document surface is moved at a speed and a time set by the scanning speed / scanning time setting unit in a length direction of the line sensor. An image reading unit that performs an operation of reading an image in a predetermined area of the document surface while moving relative to the vertical direction and scanning, and the image reading unit Image storage means for storing the captured image, image synthesis means for synthesizing a plurality of images stored in the image storage means, and image output means for outputting an image synthesized by the image synthesis means, Prepare.

In one embodiment of the present invention, the imaging lens is a zoom lens.

In one embodiment of the present invention, the shift means includes:
The image forming lens and the line sensor are integrated so as to be shifted in a direction parallel to the length direction of the line sensor.

In one embodiment of the present invention, the image output means is a display device.

In one aspect of the present invention, the image output means is a printer.

According to the image reading method of the present invention, a document surface to be read is divided into a plurality of areas in accordance with a desired reading density on the entire document surface, and an image is read at a constant reading density in each area. Then, the images read in the respective areas are combined with each other to restore the entire original surface.

In one embodiment of the present invention, the desired reading density is continuously variable.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in accordance with preferred embodiments with reference to the drawings.

First, FIGS. 2 and 3 show the configuration of an optical system of an image reading section of an image scanner according to an embodiment of the present invention using a zoom lens as an imaging lens. FIG.
FIG. 3 is a side view of the image reading unit, and FIG.

An original 7 from which an image is to be read is placed on the original platen glass 1. A slit 8 is provided below the platen glass 1 so as to face the lower surface (original surface) of the original 7. The slit 8 moves to the left in the figure along the document surface, thereby (8 (A) → 8 (B) → 8
(C)), the original surface is scanned. L ₁ is the total length of the document 7 in the scanning direction.

The first mirror 2 is disposed below the slit 8, and reflects the signal light obtained through the slit 8 from the document surface illuminated by the illumination means (not shown) to the right in the figure. The signal light reflected by the first mirror 2 is further reflected by a second mirror 3 disposed to the right of the first mirror 2 and further reflected by a third mirror 4 to form an imaging lens. It is guided to the zoom lens 5. The light is condensed on the line sensor 6 by the zoom lens 5.

First mirror 2 arranged opposite slit 8
Move with the slit 8 when the slit 8 moves (2 (A) → 2 (B) → 2 (C) in the figure). At this time, the mirror unit including the second mirror 3 and the third mirror 4 also moves in conjunction with the first mirror 2, and the moving speed is set to be half the moving speed of the first mirror 2. (3 (A) → 3 (B) → 3 (C) and 4
(A) → 4 (B) → 4 (C)). Thus, the optical path length of the signal light from the slit 8 to the zoom lens 5 is always kept constant.

The zoom lens 5 is fixed during the reading operation, but moves when the magnification is changed, for example, in the range of 5a to 5b in the drawing. In the present example, the zoom lens 5 is 1 × to 2 ×
Zooming can be performed continuously in the doubled range.

Now, by zooming of the zoom lens 5,
Assuming that the document surface is enlarged by a factor of m (1 <m ≦ 2), the reading width of the line sensor 6 (the length of the line sensor 6) is constant, so that the reading width of the document surface is 1 / m. Further, as the reading density increases, the scanning speed of the document surface by the slit 8 is also reduced to 1 / m, so that the scanning range in the normal operation time is reduced to 1 / m (L _{m in} FIG. 2).

As described above, when the original surface is magnified and read by a factor of m, the read dot size on the original surface becomes 1 / m relatively to that of the same-size reading. Therefore, at the time of enlargement, higher density image reading becomes possible.

However, in such a high-density reading, the reading range is the usual (1 / m) ² . That is, partial reading.

Therefore, in the present embodiment, high-density reading of the entire document surface is realized by the configuration described below.

FIG. 1 is a functional block diagram corresponding to a processing procedure for realizing high-density reading of the entire document surface in the image scanner shown in FIGS.

First, the user sets a document 7 to be read on the platen glass 1 of the image scanner, selects a desired reading density (for example, 600 to 1200 dpi), and, for example, displays the image on the operation panel of the image scanner. Input is made from the provided reading density input means 11.

Then, a lens magnification setting circuit 12 provided in the image scanner sets the lens magnification of the zoom lens 5 corresponding to the input reading density. Then, the imaging lens zooming mechanism 13 zooms the zoom lens 5 according to the lens magnification set by the lens magnification setting circuit 12.

Next, an imaging lens & line sensor shift amount setting circuit 1 also provided in the image scanner
For example, as shown in FIG. 3, the zoom lens 5 and the line sensor 6 are integrally shifted in the length direction of the line sensor 6 according to the lens magnification set by the lens magnification setting circuit 12 described above. Set the amount of shift to be performed.

At this time, for example, when the lens magnification is up to 2 times as in the present embodiment, as shown in FIG.
It is desirable to shift the zoom lens 5 and the line sensor 6 so that the lens optical axis O is located at each of the division positions (that is, the positions of O (E) and O (F)).

Then, in accordance with the shift amount (including the direction parameter) set by the imaging lens & line sensor shift amount setting circuit 14, the imaging lens & line sensor shift mechanism 15 (not shown) zooms. The lens 5 and the line sensor 6 are integrated into O (E) or O
Move to position (F).

Next, the scanning speed / scanning time setting circuit 16
However, according to the lens magnification set by the lens magnification setting circuit 12, the scanning speed and the scanning time in the length direction of the document surface are respectively set. That is, as described above, in accordance with the increase of the lens power, but slows the moving speed of the slit 8, at this time, in the normal scan time, not scanned only a range of L _m of FIG. Therefore, by extending the scanning time, the entire range of the document surface length L ₁ is to be scanned.

After the above setting is completed, the image reading mechanism 17 including the slit 8, the first mirror 2, the second mirror 3, the third mirror 4, the zoom lens 5, the line sensor 6, etc. is operated, and the original surface is scanned. An image in a predetermined area is read. The image data read here is stored in the image memory 18.

When the first image reading of the predetermined area on the document surface is completed, the operation returns to the setting operation of the imaging lens & line sensor shift amount setting circuit 14 and the zoom lens 5
Then, the shift position of the line sensor 6 is changed, and the second and subsequent image readings are performed.

For example, the first image reading is performed at the position O (E) in FIG.
This is performed at the position (F). Thus, the entire area of the document surface is read. Reading at this O (E) position and O (F)
Reading at the position may be performed by scanning the document surface in the same direction.However, if scanning is performed by scanning one side in the forward path and the other side in the backward path, the entire reading time can be reduced. It is advantageous. In FIG. 3, O (D) is
This is a reading position at a normal magnification (1 ×).

Next, the two pieces of image data read by the two image readings as described above are read out from the image memory 18 and are synthesized by the image synthesizing circuit 19.
Restores the entire original surface. The obtained image data of the entire document surface is output from the image output means 20 to the outside. This output data may be supplied to an external device such as a computer, or may be displayed on a display device or printed by a printer.

As described above, the image data of the entire original surface is
Since reconstruction is performed using the high-density image obtained when each partial area is read, high-density reading of the entire document surface can be performed by the above-described series of operations. The above-described series of operations are all automatically executed after the reading density is input.

FIG. 4 shows the reading range of the document surface during the high-density reading described above.

The shift positions of the zoom lens 5 are two positions of the lens optical axes O (E) and O (F) in the figure, and the readable areas E and F of the line sensor 6 are respectively surrounded by broken lines. Range. The length direction of the document 7 (sub-scanning direction)
, The normal scanning range L _m corresponding to the normal reading time
And the scan extension range by the set scan time extension.

From FIG. 4, it can be seen that the entire area of the document surface is scanned without omission. It should be noted that a scanning area that protrudes from the document according to the magnification condition can be automatically cut from the image data. Also, areas that overlap each other,
It is corrected at the time of image synthesis.

FIG. 5 shows the optical arrangement of the zoom lens 5 and the line sensor 6 at the time of high-density reading as compared with the optical arrangement at the time of reading at the same magnification.

As can be seen from FIG. 5, by shifting the zoom lens 5 and the line sensor 6 integrally to the positions E and F, respectively, it is possible to read all the images in the longitudinal direction of the line sensor 6.

The zoom lens 5 generally projects forward during enlarged reading, as shown in FIG. Even at this time, in order to enable the entire scanning in the sub-scanning direction, the zoom lens 5 is moved so that the zoom lens 5 does not extend over the moving range of the third mirror 4 even when the zoom lens 5 is at its maximum protrusion. Need to be placed.

When reading an image at a high density, as the reading density increases, the amount of image data increases, so that the required memory capacity and reading time increase. Therefore, it is desirable that the reading density can be set as finely as possible according to the type of image. Thus, in the present embodiment, the reading density can be continuously changed by using the continuous zooming of the zoom lens 5.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above-described embodiments. For example, in the above-described embodiment, the original surface is divided into two and the reading operation is performed twice, and the two pieces of image data obtained thereby are combined to restore the entire original surface. The reading operation may be performed by dividing the image data into a larger number of areas, and combining three or more pieces of image data obtained thereby to restore the entire document surface. Thereby, higher density image reading can be realized.

[0043]

According to the present invention, high-density reading of the entire original surface can be performed even when a conventionally used line sensor is used.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating a main configuration of an image reading apparatus according to an embodiment of the present invention, corresponding to an operation processing procedure thereof.

FIG. 2 is a side view schematically showing an optical system of an image reading unit of the image reading apparatus according to the embodiment of the present invention.

FIG. 3 is a plan view schematically showing an optical system of an image reading unit of the image reading device according to the embodiment of the present invention.

FIG. 4 is a conceptual diagram showing a relationship between a shift position of an imaging lens and a reading range in the image reading device according to one embodiment of the present invention.

FIG. 5 is a conceptual diagram showing a relationship between an optical arrangement of an imaging lens and a line sensor and a reading range in the image reading device according to one embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 platen glass 2, 3, 4 mirror 5 zoom lens 6 line sensor 7 document 8 slit 12 lens magnification setting circuit 14 imaging lens & line sensor shift amount setting circuit 16 scanning speed / scanning time setting circuit 18 image memory 19 image synthesis circuit

Continued on front page F term (reference) 2H107 AA02 AB02 AB22 BA06 DB01 EA15 5B047 AA01 BA02 BB02 BC05 BC14 CA05 CA07 CA11 CA17 CB07 CB09 CB10 5C072 AA05 BA09 BA16 DA02 DA23 LA02 MB03 MB08 RA06 RA12 TA04 UA11 A12 AA12A20A12A20 BB31 BB32 CB01

Claims (7)

[Claims] 1. An image forming lens having a variable magnification function, wherein a signal light from the original surface is scanned by moving the original surface to be read relatively in a direction perpendicular to the length direction of the line sensor and scanning. Image on the line sensor,
In an image reading apparatus for reading an image on the original surface, a reading density input unit for inputting a desired reading density, and a magnification of the imaging lens are set according to the reading density input from the reading density input unit. Lens magnification setting means; imaging lens magnification means for changing the magnification of the imaging lens to the magnification set by the lens magnification setting means; and a magnification of the document surface according to the magnification set by the lens magnification setting means. Shift amount setting means for setting a shift amount for relatively shifting a reading range in a direction parallel to the length direction of the line sensor; and a reading range of the document surface with the shift amount set by the shift amount setting means A shift means for relatively shifting in a direction parallel to the length direction of the line sensor, and in accordance with the magnification set by the lens magnification setting means, Scanning speed / scanning time setting means for setting the speed and time for scanning by moving the original surface relatively in the direction perpendicular to the length direction of the line sensor, and the line sensor and the imaging lens. And moving the document surface at a speed and time set by the scanning speed / scanning time setting means in a direction perpendicular to the length direction of the line sensor while scanning the document surface. An image reading unit that performs an operation of reading an image of an area; an image storage unit that stores an image read by the image reading unit; an image combining unit that combines a plurality of images stored in the image storage unit; An image reading device comprising: an image output unit that outputs an image synthesized by the image synthesis unit. 2. The image reading apparatus according to claim 1, wherein the imaging lens is a zoom lens. 3. The apparatus according to claim 1, wherein the shift unit is configured to shift the imaging lens and the line sensor integrally in a direction parallel to a length direction of the line sensor. Or the image reading device according to 2. 4. The image reading apparatus according to claim 1, wherein said image output means is a display device. 5. The image reading apparatus according to claim 1, wherein said image output means is a printer. 6. A document surface to be read is divided into a plurality of regions in accordance with a desired reading density on the entire document surface, and an image is read at a constant reading density in each region. An image reading method, wherein images read in respective areas are combined with each other to restore the entire original surface. 7. The image reading method according to claim 6, wherein the desired reading density is continuously variable.