JP2000295436A - Image reader and image reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly read an original image, even in the case that originals different in width are read or dust or the like is deposited on an original by calculating an information amount of a recording medium, depending on a detected width and a length of the recording medium and reading an image recorded on the recording medium, in response to the calculated information amount. SOLUTION: An entry means 28 or a host 20 gives a scanning instruction to the reader to set a scan mode, and a front side image sensor 4 or a rear side image sensor 9 writes image data corresponding to one line to a line memory 24 through an image processing section 23 in a processing means. A CPU 22 writes the image data corresponding to one line written in the line memory 24 to an image memory 27 by designating a write address. Then the CPU 22 writes data to the image memory 27 one after another, while changing the write address and a transmission section 26 transmits the image data stored in this image memory to the host 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus and an image reading method for reading image information using an image sensor or the like by conveying a sheet-shaped document.

[0002]

2. Description of the Related Art FIG. 13 is a sectional view showing the structure of a general image reading apparatus of this kind, and shows the structure of a sheet-through type scanner.

When a reading start instruction is given from an external device such as a host computer (not shown) or an operation panel P, the sheet-through scanner S draws the original 6 placed on the original platen 5 by the paper feed roller 1. One line of image data, which is transported by the feed roller 2, the transport roller 3, and the transport roller 12, is separated by the separation roller 13, and is read by the front image sensor 4, passes through an image processing unit (not shown). Written to line memory.

[0006] One line of image data written to the line memory by a CPU (not shown) is written to the image memory by designating a predetermined write start position X1. This one line of image data is
Is transported at a predetermined pitch and a predetermined number of times (n
), The writing position is successively written to the image memory while being changed by the CPU.

At the same time, one line of image data is written from the back image image sensor 9 into the line memory through the image processing unit. Then, the image data for one line written into the line memory by the CPU is stored in the image memory at a predetermined write start position X1.
Is specified and written. The image data for one line is sent a predetermined number of times (n times) at a predetermined pitch as the document is conveyed, so that the image data is successively written to the image memory while being changed by the CPU. Written to memory. Thereafter, the original 6 is discharged to the paper discharge tray 10 through the paper discharge rollers 7.

The paper feed roller 1, feed roller 2, transport rollers 3, 12, separation roller 13, and paper discharge roller 7 are
It is driven and rotated by a motor (not shown).

[0007] The document 6 is sandwiched by the regulating plate being moved in a predetermined direction on the document table. The restriction plate is connected to the document width detection board so that the left end position and the right end position of the document 6 can be detected. The document 6 placed on the document table 5 is fed as described above, passes through the sensor, and the length of the document 6 can be calculated from the relationship between the passage time of the sensor and the transport speed. Has become.

This is for automatically detecting the original size without specifying the original size when the original size read from an external device such as a host computer (not shown) or the operation panel P is unknown.

[0009]

However, in the above-described image reading apparatus, since the width of the original is detected by the regulating plate, when reading a bundle of originals having different widths, the original width is restricted to the maximum width. As a result, the originals had to be scanned with an extra width, even if the original was smaller than the widest original.

Therefore, a method of calculating the image width from the read image has been adopted. However, when it is difficult to distinguish between a document and a non-document, an accurate image width cannot be calculated. Further, if dust or the like adheres to the outside of the actual document width on the image sensor, the position of the dust or the like is erroneously recognized as an image edge, and the document must be read with a width larger than the actual document width. In some cases, the image width calculated from the image read by the front image sensor may be different from the image width calculated from the image read by the back image sensor. Image data had to be sent to a computer or the like.

Furthermore, if the mounting positions of the front image sensor and the rear image sensor are significantly shifted,
Since each image position is different, when calculating the image width from the image read based on either the front image sensor or the back image sensor, the image width calculated from the image read by the front image sensor is used. And an image width calculated from the image read by the back image image sensor.

The present invention has been made in view of the above-described problems, and can appropriately read a document image even when reading documents of different widths or when dust or the like is attached. It is another object of the present invention to provide an image reading apparatus and an image reading method capable of performing appropriate image reading even when the image widths of the front side and the back side are different.

[0013]

An image reading apparatus and an image reading method according to the present invention are configured as follows.

(1) In an image reading apparatus that conveys a sheet-shaped recording medium and reads an image on the recording medium,
An image sensor for reading a desired portion of the image information recorded on the recording medium, first detecting means for detecting the width of the recording medium, and second detecting means for detecting the image width on the front side of the recording medium A third detecting means for detecting an image width on the back side of the recording medium; and a fourth detecting means for detecting the length of the recording medium.
An information amount of the recording medium is calculated from the width and the length of the recording medium detected by any one of the detecting means, and an image recorded on the recording medium according to the calculated information amount. Was read.

(2) In the configuration of (1), a transfer means for transferring image information to an external device is provided.

(3) In the above configuration (1) or (2), if the image width cannot be detected by the second and third detecting means, the width detected by the first detecting means and the length of the recording medium Then, the information amount of the recording medium is calculated.

(4) In the configuration of (1) or (2), if the image width cannot be detected by the second or third detecting means, the image width detected by any of the detecting means and the recording medium The information amount of the recording medium is calculated from the length of the recording medium.

(5) In the above configuration (1) or (2), when the image widths detected by the second and third detecting means are different, the larger image width and the length of the recording medium are used to determine the size of the recording medium. The amount of information was calculated.

(6) In an image reading method for reading an image on a recording medium by conveying a sheet-shaped recording medium,
A desired portion of the image information recorded on the recording medium is read, and the width of the recording medium, the image width on the front side of the recording medium, the image width on the back side of the recording medium, and the length of the recording medium. Then, the information amount of the recording medium is calculated from any of the detected widths and the length of the recording medium, and the image recorded on the recording medium is read according to the calculated information amount.

(7) In the configuration of (6), when the image width cannot be detected from the read image information, the information amount of the recording medium is calculated from the detected width and length of the recording medium.

(8) In the above configuration (6), when the image width on either the front side or the back side cannot be detected, the information amount of the recording medium is determined from the detected image width and the length of the recording medium. It was calculated.

(9) In the above configuration (6), when the detected image width on the front side and the detected back side is different, the information amount of the recording medium is calculated from the larger image width and the length of the recording medium. did.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) A case of a sheet-through scanner will be described as an embodiment of the present invention. The sheet-through type scanner S of this embodiment is the same as that shown in FIG. 13, and when a reading start instruction is given from an external device such as a host computer (not shown) or the operation panel P,
A document 6 placed on a document table 5 is pulled in by a feed roller 1, and a feed roller 2, a transport roller 3 and a transport roller 1
When the leading edge of the original 6 reaches the position of the image sensor 4 for front image or the image sensor 9 for back image, the image is read line by line into an image memory (not shown). .

At this time, the arrival determining means of the document 6 is measured by a timer or the like (not shown) or by a document detection sensor (not shown). Then, the image of the original document 6 is
Then, the original 6 is conveyed, and is discharged to the discharge table 10 by the discharge rollers 7.

FIG. 1 is a block diagram showing a main control circuit configuration of this embodiment. In the figure, reference numeral 20 denotes a host device which is an external device connected to the scanner S, and reference numeral 21 denotes a main CPU.
An image processing unit 23 for processing image information of a document read by the image sensors 4 and 9 by a processing unit having 22;
A line memory 24 for storing image information for each line, an image width detecting section (second and third detecting means) 25 for detecting image widths on the front side and the back side of a document as a recording medium, and a host device for storing image information A transmission unit (transfer unit) 26 for transferring the data to the transmission unit 20 is provided. 27 is an image memory for storing image information, and 28 is input means for inputting various information.

Although not shown, the first detecting means for detecting the width of the original, the fourth detecting means for detecting the length of the original, and the detecting means by any one of the first to fourth detecting means. The calculating means for calculating the information amount of the document from the width and the length of the document is constituted by the processing means 21. Then, an image recorded on the document is read according to the calculated information amount of the document.

When a scan instruction is given from the input unit 28 or the host device 20, the scan mode is set, and one line of image data from the front image sensor 4 or the back image sensor 9 is processed by the image processing unit in the processing unit. 23, and is written to the line memory 24. The CPU 22 writes the image data for one line written in the line memory 24 into the image memory 27 by designating a writing position.

When the image data for one line is sent a predetermined number of times (n times) at a predetermined pitch,
The writing position is stored in the image memory 27 one after another by the CPU 22.
The image data which is written while being changed by the above and is stored in the image memory 27 is transmitted from the transmission unit 26 to the host device 20.

Here, when the image data is written from the line memory 24 to the image memory 27, FIG.
As shown in FIG. 4, the image width is detected by the image width detection unit 25. 2 shows a case of a normal document, FIG. 3 shows a case of dust or the like, and FIG. 4 shows a case of a document having a high image density.

The image data on the surface of one line connected by the line aa 'on the read original 6 in FIG. 2 becomes a voltage signal, and the image position is detected at the positions b and b' by a predetermined slice level. I do.

The image data on the surface of one line connected by the line aa 'on the read original 6 in FIG. 3 becomes a voltage signal, and the image position is detected at positions c and c' by a predetermined slice level. I do.

The image data on the surface of one line connected by aa 'on the read original 6 in FIG. 4 is a voltage signal, but the image position cannot be detected by a predetermined slice level.

FIG. 7 is a perspective view showing a configuration of a document size detecting portion in this embodiment. In the figure, reference numerals 8a and 8b denote regulating plates for sandwiching the original, which are movable in the w direction. 14
Is a document width detecting board, which is connected to the above-mentioned regulating plates 8a and 8b, and the information is transmitted to the CPU 22. Reference numeral 15 denotes a sensor that measures the length of the document 6 that has passed through the sensor 15, and that information is transmitted to the CPU 22.

When the user places the original 6 on the original platen 5,
The document 6 is regulated so as to be sandwiched between the regulating plates 8a and 8b. The restriction plates 8a and 8b are connected to the document width detection board 14, so that the left end position and the right end position of the document 6 can be detected. The document 6 placed on the document table 5 is fed as described above and passes through the sensor 15. The length of the document 6 can be calculated from the relationship between the passing time of the sensor 15 and the transport speed.

FIG. 8 is an enlarged view showing details of the regulation plate position detecting portion of FIG. A resistor is arranged on the document width detection board 14, and the position information of the regulating plates 8a and 8b is converted into a voltage value and transmitted to the CPU 22.

Next, the operation of this embodiment will be described with reference to the flowcharts of FIGS. The control processing shown in this flowchart and the flowchart in FIG. 12 described later is executed by the CPU 22 in FIG. 1 according to a program stored in advance.

When a reading start instruction is given from the host device 20 or the input means 28 (S1), the sheet-through scanner S determines whether or not the original 6 is placed on the original platen 5 by an original detection sensor. If the document 6 is placed on the document table 5, after the document width is detected by the regulating plates 8a and 8b (S2), the document 6 is pulled in by the paper feed roller 1 (S3), and When the document 6 is conveyed by the conveyance roller 3 and the conveyance roller 12 and separated by the separation roller 13 and the leading end of the document 6 reaches the position of the image sensor 4 for front image or the image sensor 9 for back image,
Based on the image reading surface information set before the start of scanning, scanning of the front surface, the back surface, or both surfaces of the routine A is started.

In the case of single-sided scanning (S4), and in the case of front-side scanning (S5, S6), image data of one line of the original 6 is sent from the image sensor 4 for the front image to the image processing unit 23 in the processing means shown in FIG. And is written to the line memory 24. The CPU 22 writes the image data for one line written in the line memory 24 into the image memory 27 by designating the write start position X1 shown in FIG. 1
The image data for the line is sent a predetermined number of times (n times) at a predetermined pitch as the document 6 is conveyed.
The data is written into the image memory 27 as shown in FIG.

In the case of back side scanning (S4, S5, S
7), image data for one line is written from the image sensor 9 for the back image to the line memory 24 through the image processing unit 23 in the processing means. The CPU 22 writes the image data for one line written in the line memory 24 into the image memory 27 by designating the write start position X1 shown in FIG. The image data for one line is given a predetermined number of times (n
As a result, the writing position is successively written to the image memory 27 while being changed by the CPU 22, as shown in FIG. 9.

In the case of double-sided scanning, the above-described front side scanning and back side scanning are performed simultaneously (S4, S8,
S9).

Next, the operation of detecting the image width in S2 will be described.

When an automatic original size detection instruction is issued from the host device 20 and an original reading start instruction is issued (S11), the CPU 22 firstly outputs voltage data indicating the position information of the regulating plates 8a and 8b to the original width detection board. Obtained from 14. Then, the obtained voltage data is A / D converted, and the position of the left end of the document 6 from the position of the regulating plate 8a and the position of the right end of the document 6 from the position of the regulating plate 8b are acquired.

Since the right and left position information has been obtained,
The document width is calculated (S12), and the number of dots (DOT) of the document width is calculated from the reading resolution. Here, the document 6 placed on the document table 5 is fed as described above,
To reach. Thereafter, image reading is started at the detected document width, and the document 6 passes through the sensor 15. The passing time of the sensor 15 is measured by a timer (not shown) or the like, and based on the speed at which the document 6 is transported, the passing time (SEC) × the transport speed (mm / sec) =
The original length (mm) is calculated, and the original length line (LIN)
E) Calculate the number.

Next, from the original width and original length obtained as described above, the size of the original to be read is calculated as: original width (DOT) ÷ 8 × original length (LINE) = original size (BYTE). I do.

Further, when writing from the line memory 24 to the image memory 27, the line a on the read original 6 shown in FIG.
The image data for one line connected by -a 'is converted into a voltage signal as shown in FIG. 2, and an image position is detected at a position of b and b' by a predetermined slice level.

Then, the image width (Wa) obtained from the above-mentioned regulating plates 8a and 8b is compared with the image width (Wb) obtained from one line of image data (S13). At this time, since the image width (Wa)> the image width (Wb), the image width of the image to be read is set to the image width (Wb) (S15).

When dust or the like is attached to the sensor 15, one line of image data connected by a line aa 'on the read original 6 in FIG. 3 is a voltage signal as shown in FIG. And an image position is detected at a position of c and c 'by a predetermined slice level. Then, the image width (Wa) obtained from the regulating plates 8a and 8b is compared with the image width (Wb) obtained from the image data for one line (S13). At this time, since the image width (Wa) <the image width (Wb), the image width of the image to be read is set to the image width (Wa) (S14).

The line a- on the read original 6 shown in FIG.
When one line of image data connected by a 'is converted into a voltage signal as shown in FIG. 4, the image position cannot be detected at a predetermined slice level. At this time, the detection of the image width (Wb) obtained from the image data for one line has failed. In this case, the image width of the image to be read is defined as the image width (Wa).

Thereafter, the original 6 passes through the sensor 15. The passage time of the sensor 15 is measured by a timer (not shown) or the like, and based on the transport speed of the original 6, the transit time (SEC) × the transport speed (mm). / Sec) =
The document length (mm) is calculated, and the number of lines of the document length is calculated from the reading resolution (S16).

Then, from the original width and original length obtained as described above, the size of the original to be read is calculated as: original width (DOT) / 8 × original length (LINE) = original size (BYTE). (S1
7).

In the above description, the line memory 24
Is calculated using one line when writing to the image memory 27, but the image width may be calculated using a plurality of lines, and the image in the image memory 27 is written while the image is being written to the image memory 27. The image width may be calculated while referring to the image, or the image width may be calculated while referring to the image in the image memory 27 after writing the image in the image memory 27.

As described above, in this embodiment, the regulating plates 8a,
The maximum width of the document 6 calculated from the left end position and the right end position of the document 6 obtained from the document width detection board 14 connected to the document width detection board 8b, the image width is also calculated from the read image, and If the image width calculated from the image read by the image sensor 4 differs from the image width calculated from the image read by the image sensor 9 for the back image, the larger width is adopted, and the restriction plate 8a, When the width exceeds the maximum width calculated from 8b, the original is read with the maximum width calculated from the restriction plates 8a and 8b.

When calculating the image width from the read image, for example, when it is difficult to distinguish between the original and the non-document, the image width calculated from the image read by the image sensor 4 for the front image and the image width for the back image If the image width detection of both the image width calculated from the image read by the image sensor 9 and the maximum width calculated from the regulation plates 8a and 8b fails, the image sensor 4 for the front image is used. If the image width calculated from the read image or the image width calculated from the image read by the image sensor 9 for the back image fails to be detected, the original is read with the image width detected successfully. Like that.

As a result, the image width to be read is always inside the regulating plates 8a and 8b, and the image widths on the front and back sides are equal, so that the accuracy of the image width detection is improved, and the image is not read with an extra width. In addition, since unnecessary image information is not given to the user, the user does not need to edit the read image and delete unnecessary portions, and thus the image reading work efficiency can be improved.

In particular, when reading an original such as a photo with a black frame where it is difficult to distinguish between the original and a non-original part, the image width is detected by the front and back reading sensors, respectively.
Since the larger width is used as the image width, image omission is eliminated, and the work efficiency of image reading can be improved.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described. FIGS. 5 and 6 are diagrams showing an image width detecting method in the present embodiment.

The image data on the surface of one line connected by the line aa 'on the read original 6 in FIG. 5 becomes a voltage signal, and the image position is detected at a position of d and d' by a predetermined slice level. I do.

The image data on the back surface of one line connected by the line aa 'on the read original 6 in FIG. 6 becomes a voltage signal, and the image position is detected at the positions of e and e' by a predetermined slice level. I do.

FIG. 12 is a flow chart showing the operation of the present embodiment based on the configuration of FIGS. 1, 5 and 6, and FIG.
7 shows the operation of image width detection.

When an automatic document size detection instruction is given from the host device 20 and an image reading start instruction is given, the CPU 22 first obtains voltage data indicating the position information of the regulating plates 8 a and 8 b from the document width detection board 14. I do. Then, the obtained voltage data is A / D converted, and the regulating plate 8a
And the position of the right end of the document 6 from the position of the regulating plate 8b.

Since the left and right position information has been obtained,
The document width is calculated, and the number of dots of the document width is calculated from the reading resolution. Here, the document 6 placed on the document table 5 is fed as described above, and reaches the sensor 15. afterwards,
Image reading is started with the detected document width (S21, S21).
23), the document 6 passes through the sensor 15. This sensor 1
5 is measured by a timer (not shown) or the like, and based on the speed at which the document 6 is transported, the transit time (SEC) × the transport speed (mm / sec) =
The document length (mm) is calculated, and the number of lines of the document length is calculated from the reading resolution.

Next, from the original width and original length obtained as described above, the size of the original to be read is calculated as: original width (DOT) ÷ 8 × original length (LINE) = original size (BYTE). I do.

Further, when writing from the line memory 24 to the image memory 27, the line a on the read original 6 shown in FIG.
The image data for one line connected by -a 'is converted into a voltage signal as shown in FIG. 5, an image position is detected at a predetermined slice level at positions d and d', and a table image width is detected ( S22).

Similarly, the back side of the original 6 shown in FIG.
The image data for one line connected by the upper line a-a 'is converted into a voltage signal as shown in FIG. 6, the image position is detected at the positions of e and e' by a predetermined slice level, and the back image width is obtained. Is detected (S24).

The image width (Wa) obtained from the above-described regulating plates 8a and 8b, the image width (Wb) obtained from the image data for one line on the front surface, and the image width (Wb) obtained from the image data for one line on the back surface. Is compared with the obtained image width (Wc) (S2
5). At this time, if the image width (Wa) <the image width (Wb) <the image width (Wc), the image width of the image to be read is set to the image width (Wa) (S26), and the image width (Wa)> (the image width (Wb) )> Image width (Wc)) If (S27), the image width of the image to be read is changed to the image width (Wc).
b) (S28), and if the image width (Wa)> (image width (Wb) <image width (Wc)) (S27), the image width of the image to be read is set to the image width (W).
c) (S29).

Here, if the detection of the image width (Wb) or the image width (Wc) fails, it is removed from the term of the above-mentioned comparison formula. Even if the front and back image detection positions b and b 'are shifted from the back and back image detection positions c and c', the image width is detected on each of the front and back sides, and thus does not depend on the mounting position of each reading sensor on the front and back sides. Here, when the amount of displacement between the front image detection positions b and b 'and the back image detection positions c and c' is large, a warning display may be performed.

Thereafter, the original 6 passes through the sensor 15. The passing time of the sensor 15 is measured by a timer (not shown) or the like, and based on the transport speed of the original 6, the transit time (SEC) × the transport speed (mm) / Sec) =
The document length (mm) is calculated, and the number of lines of the document length is calculated from the reading resolution (S30).

From the original width and original length obtained as described above, the size of the original to be read is calculated as: original width (DOT) ÷ 8 × original length (LINE) = original size (BYTE). (S3
1).

In the above description, the line memory 24
Although the image width is calculated using one line when writing to the image memory 27 from the image memory 27, the image width may be calculated using a plurality of lines. Alternatively, the image width may be calculated while referring to the image of the image memory 27. Alternatively, the image width may be calculated while referring to the image in the image memory 27 after writing the image in the image memory 27.

As described above, when detecting the read image position, the image position calculated from the image read by the image sensor 4 for the front image and the image position calculated from the image read by the image sensor 9 for the back image are detected. Is different from
The original is read after the position is corrected.

Therefore, since the image width is detected by the front and back reading sensors, it is possible to correct even if the front and back reading sensors are mechanically displaced in the width direction, and to increase the cost for improving the mounting accuracy of the reading sensor. Can be suppressed.

[0073]

As described above, according to the present invention,
Even when scanning originals of different widths or when dust is attached, it is possible to read the appropriate original image,
Further, even when the image widths of the front side and the back side are different, appropriate image reading can be performed.

That is, the document width calculated from the left end position and the right end position of the document obtained from the document width detection board connected to the regulating plate is set to the maximum width, and the image width is also calculated from the read image. If the image width calculated from the image read by the front image image sensor is different from the image width calculated from the image read by the back image image sensor, the larger width is adopted, and the width calculated from the regulation plate is used. If the maximum width is exceeded, the original can be read with the maximum width calculated from the restriction plate.

Further, when calculating the image width from the read image, for example, when it is difficult to distinguish between a document and a non-document, the image width calculated from the image read by the front image sensor and the image sensor for the back image are used. If the detection of both image widths of the image width calculated from the image read in step 2 fails, the original is read at the maximum width calculated from the regulating plate, and the image width calculated from the image read by the front image sensor and the image width If any of the image widths calculated from the image read by the image sensor fails to be detected,
The original can be read with the image width for which the image width has been successfully detected.

Further, when detecting the position of the read image,
When the image position calculated from the image read by the front image image sensor is different from the image position calculated from the image read by the back image image sensor, the document can be read with position correction.

As a result, the width of the image to be read is always inside the regulating plate, and the width of the image on the front surface is equal to the width of the image on the back surface. Does not give unnecessary image information. This eliminates the need for the user to edit the read image and delete unnecessary portions, and thus enhances the efficiency of image reading.

In particular, even when reading a document such as a photo with a black frame in which it is difficult to distinguish between the document and the non-document, the image width is detected by the front and back reading sensors, and the larger width is used as the image width. This eliminates missing images,
Work efficiency of image reading can be improved.

Further, since the image width is detected by each of the front and back reading sensors, even if the front and back reading sensors are mechanically displaced in the width direction, the cost can be increased for improving the mounting accuracy of the reading sensor. Can be suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a control configuration according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an image width detection method according to the first embodiment.

FIG. 3 is an explanatory diagram illustrating an image width detection method according to the first embodiment.

FIG. 4 is an explanatory diagram illustrating an image width detection method according to the first embodiment.

FIG. 5 is an explanatory diagram illustrating an image width detection method according to a second embodiment.

FIG. 6 is an explanatory diagram illustrating an image width detection method according to a second embodiment.

FIG. 7 is a perspective view showing a configuration of a document size detection portion.

FIG. 8 is an enlarged view showing details of a regulation plate position detection portion.

FIG. 9 is an explanatory diagram showing a write start position of an image memory.

FIG. 10 is a flowchart illustrating the operation of the first embodiment.

FIG. 11 is a flowchart showing the operation of the first embodiment.

FIG. 12 is a flowchart illustrating the operation of the second embodiment.

FIG. 13 is a cross-sectional view illustrating a configuration of a general image reading apparatus.

[Explanation of symbols]

 Reference Signs List 4 Image sensor 6 Document (recording medium) 8a Regulatory plate 8b Regulatory plate 9 Image sensor 20 Host device (external device) 21 Processing unit (detection unit, calculation unit) 22 CPU 23 Image processing unit 24 Line memory 25 Image width detection unit 26 Sending unit (transfer means) 27 Image memory 28 Input means

Claims (9)

[Claims] An image sensor for reading a desired portion of image information recorded on the recording medium, wherein an image sensor for reading a desired portion of image information recorded on the recording medium and a width of the recording medium. First detecting means for detecting, second detecting means for detecting the image width on the front side of the recording medium, third detecting means for detecting the image width on the back side of the recording medium, and the recording medium And a fourth detecting means for detecting the length of the recording medium. The information amount of the recording medium is calculated from the width detected by any of the detecting means and the length of the recording medium, and according to the calculated information amount. An image reading device for reading an image recorded on a recording medium by reading the image. 2. The image reading device according to claim 1, further comprising a transfer unit that transfers the image information to an external device. 3. The information amount of a recording medium is calculated from the width detected by the first detecting means and the length of the recording medium when the image width cannot be detected by the second and third detecting means. 3. The image reading device according to claim 1, wherein: 4. When the image width cannot be detected by the second or third detecting means, the information amount of the recording medium is calculated from the image width detected by any of the detecting means and the length of the recording medium. The image reading device according to claim 1, wherein: 5. An information amount of a recording medium is calculated from a larger image width and a length of the recording medium when the image widths detected by the second and third detecting means are different.
Or the image reading device according to 2. 6. An image reading method for conveying a sheet-shaped recording medium and reading an image on the recording medium, wherein a desired portion of image information recorded on the recording medium is read, and a width of the recording medium is adjusted. The image width on the front side of the recording medium, the image width on the back side of the recording medium, and the length of the recording medium are detected, and the information on the recording medium is obtained from any of the detected widths and the length of the recording medium. An image reading method, comprising calculating an amount and reading an image recorded on a recording medium according to the calculated information amount. 7. The information processing apparatus according to claim 6, wherein when the image width cannot be detected from the read image information, the information amount of the recording medium is calculated from the detected width and length of the recording medium. Image reading method. 8. An information amount of the recording medium is calculated from the detected image width and the length of the recording medium when any one of the image widths on the front side and the rear side cannot be detected. 7. The image reading method according to claim 6, wherein: 9. The information amount of a recording medium is calculated from the larger image width and the length of the recording medium when the detected image widths of the front side and the rear side are different. The image reading method described.