JPH0723187A - Image reader - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize an image reading device capable of reading a document at high speed with a simple configuration. [Structure] 9-1, 9-2, 9-3 are CCD sensors having spectral sensitivity characteristics of red (R), green (G), and blue (B), respectively. The image signal read by this sensor is output as a digital signal of 8-bit output 0 to 255 by the A / D converters 11-1, 11-2 and 11-3, respectively, and the shading correction units 12-1 and 12- Electrical shading correction is performed at 2 and 12-3. Since the CCD sensors 9-1, 9-2, 9-3 are arranged in parallel at a fixed distance from each other, the first switching means 13, the large-capacity image memory 14-1, and the medium-capacity image memory 14 are provided.
-2 and the delay unit by the second switching means 15,
The spatial deviation is corrected.

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 using an image sensor composed of a plurality of sensor arrays.

[0002]

2. Description of the Related Art In recent years, color scanners have been widely used, which color-separate a color original document, read it pixel by pixel, and output pixel data as digital data to a host computer or the like. When reading the color separation with the color line image sensor as shown in FIG. 2, three CCDs of RGB are used.
Since the reading position of is shifted, the reading position is corrected using the image memory. If the distance between the three CCD sensor rows corresponds to the reading resolution of 10 lines, when the R channel reads the 100th line, the G and B channels read the images of the 90th line and the 80th line, respectively. ing. In order to combine the RGB channels of the 100th line, it is necessary to hold the previously read R channel and G channel data until the B channel reads the 100th line. For this reason,
An image memory for 20 lines for the R channel and an image memory for 10 lines for the G channel are used to correct the line shift of the sensor. As described above, in the related art, since the image memory necessary for each color channel is prepared, the color scanner can read the color original document only in the designated direction, and the reading time is shortened in order to shorten the total reading time. Had a fast return speed.

[0003]

However, in the prior art, in order to increase the return speed of reading, a motor capable of rotating at a high speed in the opposite direction is required, and there is a problem that the cost is increased, and the return speed is increased. There was a limit to the speed.

The present invention has been made in view of the above prior art, and an object thereof is to provide an image reading apparatus capable of reading an image at high speed at low cost.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an image reading apparatus of the present invention which enables reading in forward and backward directions in an image reading apparatus including a plurality of sensor rows. In addition, a switching means for switching the channel of the image memory for delaying the image data is provided.

[0006]

According to the present invention, with the above-mentioned structure, an image reading apparatus which can be read at a high speed at a low price can be obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3, and a second embodiment of the present invention will be described with reference to FIGS.
Will be described with reference to. In the following embodiments, an example of a scanner is shown as an application example of the present invention, but the present invention is not limited to this, and it goes without saying that it can be applied to various other devices such as a digital copying machine and a facsimile.

FIG. 1 shows an example of a schematic internal configuration of a color scanner according to the first embodiment of the present invention.
In FIG. 1, 1 is a color scanner, 2 is an automatic document feeder, a document 3 is sent on a document table 4, and an optical housing 5 is provided.
Is illuminated by a lamp 6 and guided to a mirror 7 to form an image on a 3-line type image sensor 9 by a lens 8.
Full color information Red (R), Green (G), Blue (B)
It is sent to the signal processing unit 10 as a component. The optical housing 5
Scans the entire surface of the original by mechanically moving at a speed v in a direction perpendicular to the electrical scanning direction of the line sensor. In the mechanical scanning direction, scanning can be performed in the return direction opposite to the forward direction shown by the arrow in FIG. FIG. 2 is an external view of the 3-line image sensor 9, and 9-1, 9-2, and 9-3 have spectral sensitivity characteristics of red (R), green (G), and blue (B), respectively. It is a CCD sensor.

FIG. 3 is a block diagram of the signal processing unit 10.
The image signals read by the 3-line image sensor 9 are output as digital signals with 8-bit outputs 0 to 255 by the A / D converters 11-1, 11-2 and 11-3, respectively, and the shading correction unit 12- Electrical shading correction is performed at 1, 12-2, 12-3. Since the CCD sensors 9-1, 9-2, 9-3 used in the first embodiment are arranged in parallel at a fixed distance, the first switching means 13 and the large-capacity image memory 14-1. The spatial shift is corrected by the delay unit including the medium capacity image memory 14-2 and the second switching means 15.

Now, the resolution of the color scanner is 300 DPI.
(Dots / Inch), the distance between the CCD sensors 9-1, 9-2, and 9-3 is 10 lines, and the number of pixels of each is 2500. When the mechanical scanning direction of the color scanner 1 is the forward direction, the R sensor (9-1) is 20 lines ahead of the B sensor (9-3) and the G sensor (9-2) is the B sensor (9-3). Since the original image of 10 lines ahead of) is read, it is necessary to store only 2500 × 20 = 50000 bytes and 2500 × 10 = 25000 bytes of data in the image memory. Therefore, the large-capacity image memory 14-1 and the medium-capacity image memory 14-2 have capacities of 50000 bytes and 25000 bytes or more, respectively. In this case, the first switching means 13 outputs the R signal to the large-capacity image memory 14
-1 to store the G signal in the medium capacity image memory 14-2.
The B signal signals the delay channel to pass through, as stored in. The second switching means 16 functions to switch the outputs of the large-capacity image memory 14-1, the medium-capacity image memory 14-2 and the through to the GRB channel.

When the mechanical scanning direction of the color scanner 1 is the return direction, the B sensor (9-3) is replaced by the R sensor (9-1).
20 lines ahead of G sensor (9-2) is R sensor (9-1)
Since the original image is read 10 lines ahead of the above, it is necessary to store only 2500 × 20 = 50000 bytes and 2500 × 10 = 25000 bytes of data in the image memory.
In this case, the first switching means 13 causes the G signal to be stored in the large capacity image memory 14-1 so that the B signal is stored in the large capacity image memory 14-1.
The R signal signals the delay channel to pass through, as stored at 14-2. And the second switching means
Reference numeral 15 serves to switch the outputs of the large-capacity image memory 14-1, the medium-capacity image memory 14-2, and the through to the BGR channel. As described above, the color scanner 1 is corrected by the delay unit for spatial misalignment of color channels due to mechanical scanning in both directions.

Reference numeral 16 is a filter processing unit for correcting the spatial frequency of the image signal. A color correction unit 17 performs color correction processing because the spectral sensitivity of the three-line image sensor 9 is not ideal. Reference numeral 18 denotes a gradation conversion unit, which performs gamma correction of the CRT and conversion into a density signal. A host interface 19 communicates with the host computer.

The color scanner 1 can realize high-speed reading by continuously using the automatic document feeder 2 and reciprocally reading, and obtains image data even when performing pre-scanning for obtaining advance information of an image document. The reading time can be shortened by mechanically scanning the main scans in the opposite directions.

FIG. 4 shows an example of a schematic internal structure of a fixing type monochrome scanner according to the second embodiment of the present invention. In FIG. 4, 20 is a contact type monochrome scanner, 21
Is an automatic document feeder, and a document 22 is conveyed onto a platen glass 23, illuminated by a lamp 25 in an optical housing 24, an image is formed on a contact image sensor 27 by a SELFOC lens 26, and a monochrome image is formed. Signal processing unit as information
Sent to 28. The optical housing 24 (25, 26, 27) has a speed v
Scans the entire surface of the original by mechanically moving in a direction perpendicular to the electrical scanning direction of the line sensor. In the mechanical scanning direction, it is possible to scan in both the forward direction and the reverse direction indicated by the arrow in FIG. Further, FIG. 5 shows the shape of the contact image sensor 27, in which the image sensors 27-1, 27-2, 27-3, 27-4 are arranged on the staggered legs, and each sensor has four areas. Are shared and read. FIG. 6 shows a block diagram of the signal processing unit 28. Image sensor 27-1, 27
Image signals read by -2, 27-3, 27-4 are A /
The D converters 29-1, 29-2, 29-3 and 29-4 output 8-bit digital signals each having an output of 0 to 255, and shading correction units 30-1, 30-2, 30-3 and 30-. At 4, electrical shading correction is performed. Since the image sensors 27-1, 27-2, 27-3, 27-4 used in the second embodiment are arranged in a staggered pattern, the first switching means 31, the image buffer memory 32-1, The spatial shift is corrected by the delay unit composed of 32-2 and the second switching means 33. Now, the resolution of the scanner is 200 DPI (Dots / Inch), and the distance between the image sensors 27-1 and 27-3 and the image sensors 27-2 and 27-4 is 10
The number of pixels of each of the line and image sensors 27-1, 27-2, 27-3, 27-4 is 400, and the total is 1600 pixels.

When the mechanical scanning direction of the fixing type monochrome scanner 20 is the forward direction, the image sensors 27-1, 27-3 read the original image 10 lines ahead of the image sensors 27-2, 27-4. Therefore, the image buffer memories 32-1 and 32-2 have 40
0x10 = image memory of 4000 bytes or more. In this case, the first switching means 31 includes shading correction units 30-1 and 30.
Signals from -3 are image buffer memories 32-1 and 32, respectively.
-2, so that the shading correction unit 30-2, 30
The signal from -4 should pass through the through signal line. Then, the second switching means 33 is provided with the image buffer memories 32-1 and 32-2.
To the first and third channels, respectively, and the two through signals to the second and fourth channels, respectively.

When the mechanical scanning direction of the fixing type monochrome scanner 20 is the return direction, the image sensors 27-2 and 27-4 read the original image 10 lines ahead of the image sensors 27-1 and 27-3. There is. In this case, the first switching means 31 is arranged so that the signals from the shading correction units 30-2 and 30-4 are stored in the image buffer memories 32-1 and 32-2, respectively. The signal from 30-3 should pass through the through signal line. The second switching means 33 switches the buffer memories 32-1 and 32-2 to the second channel and the fourth channel, respectively, and the two through signals to the first channel and the third channel, respectively. As described above, the delay unit corrects the spatial displacement of the image sensor array in the contact type monochrome scanner 20 due to mechanical scanning in both directions.

Reference numeral 34 denotes a channel synthesizing unit which synthesizes the read signals from the four image sensors 27-1, 27-2, 27-3 and 27-4 into one channel signal. A filter processing unit 35 corrects the spatial frequency of the image signal. Reference numeral 36 is a gradation conversion unit, which performs gamma correction of the CRT and conversion into a density signal. A host interface 37 communicates with the host computer. In the second embodiment, the contact type image sensor is a monochrome example, but a color contact type image sensor can read at high speed with the same configuration. High-speed reading can be realized by continuously using the automatic document feeder 2 and reciprocally reading as in the first embodiment, and image data can be read even when pre-scanning for obtaining advance information of an image document is performed. The main scan for obtaining mechanically scans in opposite directions, so that the reading time can be shortened.

[0018]

As is apparent from the above embodiments, according to the present invention, it is possible to provide an inexpensive image reading apparatus capable of reading a document at high speed.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a color scanner according to a first embodiment of the present invention.

FIG. 2 is a shape diagram of a 3-line type image sensor according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a signal processing unit in the first embodiment of the present invention.

FIG. 4 is a schematic diagram of a monochrome scanner according to a second embodiment of the present invention.

FIG. 5 is a shape diagram of a contact image sensor according to a second embodiment of the present invention.

FIG. 6 is a block diagram of a signal processing unit according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... Color scanner, 2, 21 ... Automatic document feeder,
3, 22 ... Originals, 4, 23 ... Original platen glass, 5, 24 ... Optical housing, 6, 25 ... Lamp, 7 ... Mirror, 8 ... Lens, 9 ... 3-line type image sensor, 10, 28 ... Signal processing , 11, 29 ... A / D converter, 12, 30 ... Shading correction section, 13, 31 ... First switching means, 14-1 ... Large-capacity image memory, 14-2 ... Medium-capacity image memory, 15, 33
... second switching means 16,35 ... filter processing section 17 ...
Color correction unit, 18, 36 ... Gradation conversion unit, 19, 37 ... Host interface, 20 ... Contact type monochrome scanner, 26 ... Self-occ lens, 27 ... Contact type image sensor, 32
-1, 32-2 ... Image buffer memory, 34 ... Channel composition section.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H04N 1/107 1/40 7251-5C H04N 1/04 D 4226-5C 1/40 G

Claims (3)

[Claims] 1. An image reading apparatus capable of reading an image original in a forward direction and a backward direction, wherein an image sensor including a plurality of sensor rows and a multi-channel image signal from the image sensor are converted into digital data of a plurality of channels. An A / D converter, a first switching unit for switching the digital data to a predetermined delay channel, an image memory for storing digital data in the delay channel, and a second switching unit for switching the delay channel to a normal channel. An image reading apparatus comprising a switching unit. 2. The image reading apparatus according to claim 1, wherein the pre-scan for obtaining the advance information of the image original and the main scan for obtaining the image data are read in directions opposite to each other. 3. The image reading apparatus according to claim 1, further comprising a document feeding unit that feeds a plurality of pages of image documents.