JPH07193690A - Image reader - Google Patents

Abstract

PURPOSE:To read an original picture correctly even when a distance between a source document (original picture) and a line sensor is changed. CONSTITUTION:A reflecting mirror 16 is provided between a horizontal scanning line 12 preceding in the vertical scanning direction (preceding horizontal scanning line) and a lens 17 or provided between a horizontal scanning line 13 succeeding in the vertical scanning direction (succeeding horizontal scanning line) and the lens 17, and main rays 14, 15 of both the horizontal scanning lines 12, 13 are made in parallel by allowing the mirror 16 to reflect the light from the preceding horizontal scanning line 12 and the light from the succeeding horizontal scanning line 13. Thus, even when the distance between line sensors 18, 19 and the source document 11 is changed, the distance L0 between the horizontal scanning lines 12, 13 read by both the line sensors 18, 19 is always made constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a plurality of line sensors arranged in the main scanning direction and relatively moves the line sensor and a document in the sub scanning direction (direction orthogonal to the main scanning direction). Accordingly, the present invention relates to an image reading apparatus that obtains image data of an image (original image) of a document.

[0002]

2. Description of the Related Art In order to read an original image with high resolution, it is necessary to arrange a large number of photoelectric conversion elements in one line in the main scanning direction. It is difficult to manufacture a line sensor unit that has a perfect photoelectric conversion element (as described above) and has the characteristics of all the elements.

Therefore, this problem is solved by using a plurality of line sensors. Various types of conventional image reading apparatus will be described with reference to FIGS. 7 and 8. Figure 7
(A) is a system disclosed in Japanese Examined Patent Publication No. 57-46266, in which two plane mirrors 6 are placed between a document 61 and a lens system 62.
One main scanning line 65 on the original 61 is reflected in two directions by arranging 3, 64 at a slight angle in a V shape. The light reflected by the plane mirrors 63 and 64 is received by the line sensors 66 and 67 provided respectively. These two line sensors 6
Reference numerals 6 and 67 read images on the front side and the other side (in FIG. 7A) of the main scanning line 65. The number of line sensors may be three or more.

FIG. 8 (a) shows a system disclosed in Japanese Patent Laid-Open No. 60-226273, in which two line sensors 76 and 77 having a relatively low resolution (three or more may be used) are used and each line is used. Both line sensors 76 and 77 are arranged so as to be slightly shifted (by half the arrangement pitch of photoelectric conversion elements in one line sensor) so that the photoelectric conversion elements forming the sensors 76 and 77 are alternately arranged in the main scanning direction. Then, the image data read by both are rearranged for each pixel signal of one column to obtain high-resolution image data. In this case, the two line sensors 76 and 77 read separate main scanning lines 72 and 73, respectively. Focusing on one main scanning line (for example, the main scanning line 73 in the lower part of FIG. 8A), there is a deviation in the time when the scanning line 73 is read by both line sensors 77 and 76 (both Main scanning line 7
Time L1 obtained by dividing the distance L1 between 3 and 72 by the sub-scanning speed v
/ V)), line sensor 76 that reads the preceding main scanning line 72 (hereinafter referred to as the first line sensor)
The image data read by is delayed by the time L1 / v (usually, the delay is performed by holding it in the memory 78 for that time), and then in the image data synthesizing unit 79, the subsequent main scanning line 73 Is combined with the image data read by the line sensor 77 (second line sensor).

[0005]

In any of the above-mentioned conventional image reading apparatuses, when the originals 61 and 71 are displaced in the direction perpendicular to the moving direction (or when the reading surfaces of the originals 61 and 71 are uneven). ), There is a drawback that accurate reading is not possible. That is, in the case of FIG. 7, when the document 61 is displaced downward as shown in FIG.
The main scanning lines read by 6 and 67 are displaced in the sub-scanning direction, and the two line sensors 66 and 67 are separated by the main scanning lines 65a and 65b.
To read. The same applies when the document 61 is displaced upward. Further, in the case of FIG. 8, as shown in FIG. 8B, when the distance between the document 71 and the line sensors 76 and 77 changes, the leading and trailing masters read by the line sensors 76 and 77 are read. Distance L1 between scanning lines 72 and 73
Changes (in the case of FIG. 8B, it becomes smaller as L2 (<L1)). In this case, in the data synthesizing unit 79, the image data read by both the line sensors 76 and 77 is separated by the distance L.
Since image data composition processing is performed on the assumption that there is a difference of 1 (that is, delayed by time L1 / v), if the distance changes to L2 (delay time L2 / v) The combined image data does not correctly reflect the image (original image) on the document 71, and is erroneous.

The present invention has been made to solve such a problem, and an object of the present invention is to correct the original image even if the distance between the original (original image) and the line sensor changes. An object is to provide a readable image reading device.

[0007]

The image reading apparatus according to the present invention made to solve the above-mentioned problems is a) that the preceding main scanning line preceding in the sub-scanning direction on the original image is passed through the optical system. A first line sensor for reading, b) a second line sensor for reading a subsequent main scanning line that follows the original image in the sub-scanning direction through the optical system, and c) a reading for the first line sensor. Image data combining means for delaying the acquired image data by the time required for scanning in the sub-scanning direction between both main scanning lines and combining with the image data read by the second line sensor; d) preceding main scanning Line between the main scanning line and the optical system, or between the following main scanning line and the optical system, both main scanning lines by reflecting the light from the preceding main scanning line or the light from the following main scanning line. And a reflector arranged so that the chief rays of There.

[0008]

The reflecting mirror 16 is, as shown in FIG. 1, for example, the main ray 15 of the following main scanning line (of the optical axis connecting the following main scanning line 13 and the second line sensor 19 to the original 11). By reflecting the near portion), the main ray 15 of the following main scanning line
And the main ray 14 of the preceding main scanning line (the portion of the principal ray connecting the preceding main scanning line 12 and the first line sensor 18 that is closest to the original 11) are made parallel to each other. Alternatively, as shown in FIG. 2, the preceding main scanning line chief ray 14 is reflected to make the preceding main scanning line chief ray 14 and the following main scanning line chief ray 15 parallel to each other. As a result, the manuscript 11
Even if the distance between the line sensor 18 and the line sensors 18 and 19 changes, the distance L0 between the leading main scanning line 12 and the succeeding main scanning line 13 is always constant, and the delay time L0 / v also changes. do not do.

The number of subsequent main scanning lines is not limited to one, but may be plural. That is, three or more main scanning lines may be simultaneously read by the corresponding line sensors. In this case, the reflecting mirror is provided between all the main scanning lines other than one main scanning line and the optical system so that the angle of the chief ray is the same as that of the one main scanning line. That is, all chief rays have the same angle).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading apparatus (flat scanner) according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 3, the flat scanner 31 of the present embodiment includes a lower frame 32.
And an upper frame 33, a document placing device 34 is provided on the upper surface of the lower frame 32, and a reading optical system is provided inside the upper frame 33. The document placing device 34 includes a document table 35 movable in the sub-scanning direction (arrow) and a drive mechanism 43 for driving the document table 35. The manuscript table 35 can hold the manuscript 36 between a pair of upper and lower glass plates, but in some cases, the upper glass plate is removed and the manuscript 36 is placed on the lower glass plate. You can also read the image with. Below the document placing device 34,
Slit light source 37 for slit exposure of transparent original
Are arranged.

In the reading optical system of the upper frame 33, a reflection light source 38 for slit exposure of the reflection original, and an original 3 are provided.
A first reflecting mirror 41 that reflects the light from the light source 6 at a substantially right angle, a second reflecting mirror 39 that will be described later, and one collection for forming the light from the document 36 on the CCD line sensor 40a and 40b. Optical lens 42 and two CCD line sensors 40
a and 40b are provided.

Two CCD line sensors 40a and 40b
Indicates the sub-scanning direction (vertical direction in FIG. 4) as shown in FIG.
They are arranged offset to each other and in the main scanning direction (left and right direction in FIG. 4).
Are arranged side by side so as to slightly overlap each other.
As a result, the first CCD line sensor 40a arranged below reads the right half (in FIG. 4) of the preceding main scanning line 45a of the original document 36, and the second CC arranged above is read.
The D line sensor 40b reads the left half of the main scanning line 45b that follows. The second reflecting mirror 39 is arranged between the condenser lens 42 and the first reflecting mirror 41 so as to totally reflect the following reading light 46b of the second CCD line sensor 40b, and the arrangement angle of the second reflecting mirror is: The preceding reading light 46a of the first CCD line sensor 40a and the following reading light 46b of the second CCD line sensor 40b are adjusted to be parallel to each other just above the original document 36. The amount of deviation between the preceding main scanning line 45a and the succeeding main scanning line 45b, that is, the distance in the sub-scanning direction between both main scanning lines 45a and 45b, is divided by the pitch of the main scanning lines. Be N.

As shown in FIG. 5, the preceding main scan line 45
The image signal generated by the first CCD line sensor 40a for reading a is converted into image data for each pixel by the A / D converter 51a and stored in the memory 52. The memory 52 is provided with N line memories having the same data capacity as the number M of pixels of the first CCD line sensor 40a (the number of photoelectric conversion elements forming the first CCD line sensor 40a). In addition, the memory 52 outputs what is called a FIFO (First
In First Out) has become a memory. The image signal generated by the second CCD line sensor 40b that reads the subsequent main scanning line 45b is converted into image data for each pixel by the A / D converter 51b, and then immediately sent to the image data synthesizing unit 53. .

The CPU 50 uses the drive mechanism 43 (FIG. 3).
Is controlled to move the document table 35 at a predetermined speed, and the both A / D converters 51 are moved at a time pitch according to the speed.
A and 51b are made to perform A / D conversion of the image signal from both CCD line sensors 40a and 40b. Then, the image data of the N main scanning lines before is read from the memory 52,
It is sent to the image data composition unit 53. As a result, the image data on the same main scanning line on the original 36 is simultaneously input to the image data combining unit 53. The image data synthesizing unit 53 adjusts the overlapping portion of the image data from the CCD line sensors 40a and 40b to generate correct image data of one main scanning line.

As described above, in the portion for processing the image data, it is premised that the amount of deviation between the two main scanning lines 45a and 45b is N, but in the flat scanner 31 of the present embodiment, the reading optical system described above is used. A second reflecting mirror 39 is provided, and both CCs
Since the reading lights of the D line sensors 40a and 40b are parallel to each other in the immediate vicinity of the document 36, even when the document table 35 moves up and down or the document 36 has irregularities, both main scanning lines 45a,
The deviation amount N between 45b does not change, and the image data composition unit 53 always composes correct image data. Further, since the preceding reading light 46a is reflected by the second reflecting mirror 39 and approaches the succeeding reading light 46b, both main scanning lines 45a, as compared with the case where the second reflecting mirror 39 is not provided,
The distance between 45b becomes smaller. This allows the memory 5
The amount of data to be stored in 2 (M × N in the above case) is small (for example, M × N 2 data. Here,
It also has the advantage of N2 <N).

CCD line sensors 40a, 40b
Is in the sub-scanning direction (vertical direction in FIG. 6) as shown in FIG.
It is also possible to displace them and shift them by a half of the arrangement pitch of the photoelectric conversion elements in the line sensor in the main scanning direction (left and right direction in FIG. 6). As a result, the first CCD line sensor 40a arranged below reads the preceding main scanning line 45a of the document 36, and the second CCD line sensor 40a arranged above is read.
The CCD line sensor 40b reads the main scanning line 45b which follows the preceding main scanning line 45a, which is shifted by half the arrangement pitch of the photoelectric conversion elements. Second reflecting mirror 39
Between the condenser lens 42 and the first reflecting mirror 41, the second CC
The D line sensor 40b is arranged so as to totally reflect the following reading light 46b, and the second reflecting mirror 39 is arranged at an angle of the original 3
Directly above 6 is adjusted so that the preceding reading light 46a of the first CDD line sensor 40a and the following reading light 46b of the second CCD line sensor 40b are parallel.

Also in this case, an electric circuit as shown in FIG.
The image data from the line sensors 40a and 40b is rearranged into an image signal of one column to generate correct image data of one main scanning line.

[0018]

According to the present invention, in a document reading device in which a plurality of line sensors read different main scanning lines of an image (original image) on a document, all the main rays of each main scanning line are made parallel to each other. Is displaced in the direction perpendicular to the surface, or the original has irregularities, so that even if the distance between the original and the line sensor changes, the distance between the main scanning lines being read is always constant. To be kept. Therefore, distortion does not occur in the image data of the original image obtained by combining the image data generated by the plurality of line sensors.

Further, in the image reading apparatus according to the present invention, since one principal ray is reflected and brought close to the other principal ray,
There is also an advantage that the distance between both main scanning lines becomes small and the capacity of the memory for storing image data between both main scanning lines can be small.

[Brief description of drawings]

FIG. 1 is a first explanatory diagram for explaining the content of the present invention.

FIG. 2 is a second explanatory diagram for explaining the content of the present invention.

FIG. 3 is a side sectional view showing the overall configuration of an image reading apparatus that is an embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration of a main part of the image reading apparatus according to the embodiment.

FIG. 5 is a block diagram showing an electric circuit of the image reading apparatus according to the embodiment.

FIG. 6 is a perspective view showing a configuration of a main part of an image reading apparatus according to another embodiment.

FIG. 7 is a perspective view showing a configuration of a main part of a first example of a conventional image reading apparatus using a plurality of line sensors.

FIG. 8 is a perspective view showing a configuration of a main part of a second example of a conventional image reading apparatus using a plurality of line sensors.

[Explanation of symbols]

Reference numerals 11 and 36 ... Original 12 ... Leading main scanning line 13 ... Trailing main scanning line 14 ... Leading main scanning line principal ray 15 ... Trailing main scanning line principal ray 16 ... Reflecting mirror 17 ... Lens 18 ... First line sensor 19 Second line sensor 31 Flat scanner 39 Second reflecting mirror 40a, 40b CCD line sensor 42 Condenser lens 45a Preceding main scanning line 45b Subsequent main scanning line 46a Preceding reading light 46b Subsequent Reading light

Claims (1)

[Claims] 1. A first line sensor for reading a preceding main scanning line preceding in the sub-scanning direction on the original image via an optical system, and b) a sub-scanning direction on the original image via the optical system. The second line sensor that reads the subsequent main scanning line following c) and c) the image data read by the first line sensor is delayed by the time required for scanning in the sub-scanning direction between both main scanning lines. And an image data synthesizing means for synthesizing the image data read by the second line sensor, and d) provided between the preceding main scanning line and the optical system or between the following main scanning line and the optical system. And a reflecting mirror arranged so that the chief rays of both main scanning lines are parallel to each other by reflecting the light from the preceding main scanning line or the light from the following main scanning line. Reader.