JP2000196869A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader which is superior in read image quality to properly read and image, even when carrying errors occur due to difference in the kinds of sheets. SOLUTION: If the length of a read image is within (with respect to a preset document length)±5%, normal operation is decided, even if the carrying the force of a friction piece 3b, a carrying roll 3e, etc., for a document D is slightly different from the designed to bring about image expansion or image reduction, and the read image is subjected to image processing of variable magnification corrections only in the document-carrying direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus for reading an image on a conveyed sheet.

[0002]

2. Description of the Related Art Conventionally, this type of image reading apparatus is provided as an original reading apparatus in, for example, a scanner, a facsimile, a multifunction machine (multi-printer, multi-copy machine, etc.).

In an apparatus such as a facsimile or a multifunction peripheral, an optical reading system for reading image information, a recording system for forming an image on the surface of a sheet, an operation panel for performing various operations, and an electrical device for performing these operations are provided. And the like.

A conventional image reading apparatus will be described below with reference to FIG. 11 using a facsimile apparatus as an example.

FIG. 11 is an explanatory sectional view of a facsimile apparatus according to the prior art.

The optical reading system 103 is provided with a document tray 109 for guiding the document D in order to smoothly feed the document D to an automatic document feeder (ADF) that feeds the document D while separating the documents one by one. Have been.

The optical reading system 103 is configured such that a user can easily set a document D, and a document is set on an upper portion of an operation panel 105 in order to reduce the size of the apparatus. 109 is the operation panel 10
5 is provided on the upper part.

The optical reading system 103 includes the cartridge cover 1
The original D placed on the original placing table 102a provided integrally with the original 02 is sent to the friction piece 103b by the separation roller 103c pressed against the preliminary pressure contact arm 103a, and the friction piece 103b and the separation roller 103c made of rubber material are used. To separate and feed each sheet.

Further, the sheet is conveyed to a contact image sensor 107 which is an image reading means by a conveying roller 103d pressed by a pressing spring (not shown) and a conveying roller 103e pressed against the conveying roller 103d.

Then, the original D is pressed against the close contact type image sensor 107 by the original
After reading the image information, the document D is discharged to the front side (left side in the figure) of the operation panel 105 by the discharge roller 103f pressed by the pressing spring and the discharge roller 103g pressed against the discharge roller 103f.

The recording system 104 is provided with a universal paper feeder for setting the width of the slider 115C in accordance with the width of the recording paper P.

The paper feeding device is provided with a recording paper feeding tray 108 for feeding recording paper. The recording paper is fed from the recording paper feeding device into the apparatus main body, and an electrophotographic image is formed on the surface of the sheet. After the toner image is formed by the method, the image is discharged to the outside of the apparatus (discharge tray 110).

[0013]

However, in the case of the above-described prior art, the following problems have occurred.

In the conventional reading system described above, the originals separated one by one are separated by a separation roller 103.
c, the document is conveyed to the contact type image sensor 107 serving as image reading means by the conveying roller 103d pressed by the conveying roller 103e and the pressing spring, and the rear end of the document is
Until it passes 3b, the back surface of the document is conveyed while receiving resistance from the friction piece 103b made of a rubber material.

Here, the coefficient of friction of the friction piece 103b with the rubber material greatly changes depending on the paper quality (sheet type) of the document, and thus the transport load greatly changes.

Accordingly, the actual conveyance force varies depending on the type of paper, which greatly affects the elongation of the read original.

In an actual machine, paper (plain paper) generally used is used as a representative paper (reference sheet), and transport rollers 103e, which are main transports, are controlled so as to have a required feed amount.
Roller diameter is determined. On the other hand, in the case of art paper, which is not often used, and has a relatively smooth surface called art paper, the coefficient of friction of rubber becomes large. Depending on the device, the document is conveyed while sliding by about 2 mm, and is read as if the document had a document length of about 299 mm.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to read an image properly even if a conveyance error occurs due to a difference in sheet type. An object of the present invention is to provide an image reading apparatus having excellent quality.

[0019]

According to the present invention, there is provided an image reading apparatus provided with a reading means for reading an image on a sheet to be conveyed, wherein an image read by the reading means is provided. It is characterized in that a magnification correcting means for correcting the magnification in the error in the sheet conveying direction and reading it as read image data is provided.

Therefore, even if a transport error occurs due to the sheet transport during the transport of the sheet, the error is corrected by the magnification correcting means, and proper read image data is obtained.

Detecting means for detecting the length of the sheet to be conveyed in the conveying direction is provided, and an error between the length based on the detection result of the detecting means and the previously recognized length of the sheet in the conveying direction is multiplied by the magnification. The magnification correction may be performed by the correction unit.

It is preferable that the length of the standard sheet that can be conveyed is set in advance and recognized.

A length based on the detection result of the detection means;
An error between the length and the closest length of the plurality of lengths of the sheet in the conveyance direction may be corrected for magnification by the magnification correcting means.

The length based on the detection result of the detection means is:
The magnification correction may be performed by the magnification correcting means only when the recognized length of the sheet in the transport direction is within a predetermined range.

Preferably, the predetermined range is a range of 95% or more and 105% or less with respect to the length of the recognized sheet in the transport direction.

The length of the sheet in the conveying direction can be recognized in advance by a user's input.

Separating means for separating and feeding a plurality of stacked sheets one by one, and feeding while using the separating function of the separating means, or feeding without using the separating means by releasing the separating function. It is preferable that the apparatus has a selecting unit for selecting whether to perform the magnification correction by the magnification correcting unit only when feeding is performed while using the separating function of the separating unit.

Only when the paper is fed while using the separating function of the separating means, the magnification correction can be performed by the magnification correcting means only in a range where a load is applied in the transport direction by the separating function.

[0029]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) An image reading apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

In the present embodiment, a facsimile apparatus will be described as an example of an image reading apparatus.

FIG. 1 is a schematic perspective view of the entire image reading apparatus (facsimile apparatus) according to the embodiment of the present invention, and FIG. 2 is a schematic sectional view of the entire image reading apparatus according to the embodiment of the present invention. FIG. 3 is a block diagram of the recording control, FIG. 4 is a detailed view of the document separating section, and FIG.
9 is a flowchart showing control for converting an image actually read by the reading device.

First, the overall configuration of an image forming apparatus (facsimile apparatus) will be schematically described with reference to FIGS.

Reference numeral 1 denotes an apparatus main body, and reference numeral 2 denotes a cartridge cover that is configured to be able to stack a plurality of originals D and that is used in common on an original mounting table.

Reference numeral 3 denotes an optical reading system (reading means) for reading image information of the document D, and reference numeral 4 denotes a recording system including a laser beam printer.

Reference numeral 5 denotes an operation panel provided on the upper front surface of the apparatus main body 1.

8 is a recording paper feed tray, 9 is a document tray,
Reference numeral 10 denotes a recording paper discharge tray, which is formed of a molding material, and is provided above the cartridge cover 2, respectively.

Reference numeral 15 denotes a recording paper feeder for setting a recording sheet P made of paper, synthetic resin, or the like.
Is a recording paper separating roller for feeding the recording sheets P from the recording paper feeding device 15 to the recording system 4 one by one.

In the optical reading system 3, first, the separation roller 3c presses the original D placed on the original placing table 2a provided integrally with the cartridge cover 2 against the preliminary pressing arm 3a.
, And is separated and fed one by one by the friction piece 3b and the separation roller 3c.

The conveying roller 3d pressed by a pressing spring (not shown) and the conveying roller 3e pressed against the conveying roller 3d are conveyed to the close contact type image sensor 7 serving as image reading means. After reading the image information of the original D while pressing the original D against the close contact type image sensor 7 and reading the image information of the original D, the apparatus is configured by a discharge roller 3f pressed by the pressing spring and a discharge roller 3g pressed against the discharge roller 3f. It is designed to be discharged outside.

If a jam of the document D occurs during the reading operation, the document D staying inside can be taken out by opening the operation panel 5 screwed to the upper guide 24. It has become.

The document table 2a is provided with a slider 2c slidable in a direction perpendicular to the direction in which the document D is conveyed (the width direction of the document D). Both edges of the stacked originals D can be regulated and aligned.

Next, in the recording system 4, a modulation signal is emitted from a laser beam oscillator (not shown) of the laser scanner unit 11 based on an image signal output from a control unit (not shown), and this modulated beam is reflected by the polygon mirror 11a and turned back. The mirror 11b irradiates the surface of the photosensitive drum 12b of the image forming unit 12 with light.

The photosensitive drum 12b is a primary charging roller 12
By d, the surface is uniformly charged, and the surface of the photosensitive drum 12b is irradiated with scanning light by irradiating the surface with a scanning beam to form a latent image on the surface of the photosensitive drum 12b. Toner is supplied to the latent image from the toner tank 12f by the developing roller 12e, and the image is visualized on the surface of the photosensitive drum 12b. The photosensitive drum 12b includes a primary charging roller 12d and a developing roller 12e.
The toner cartridge 12a, the toner tank 12f, and the cleaning blade (not shown) are integrally incorporated in the recording cartridge 12a, and are configured to be detachable from the apparatus main body 1.

The recording cartridge 12a can be replaced by opening the cartridge cover 2.

A transfer roller 12c serving as a transfer charger is disposed at a position facing the photosensitive drum 12b of the image forming section 12, and a thermal fixing device 17 is provided on a recording sheet conveying path downstream of the photosensitive drum 12b. , A discharge roller pair 18, a guide unit 20, and a discharge roller pair 13 are sequentially arranged.

The heat fixing device 17 includes a heater 17 as a heating element.
a, a pressure roller 17b pressed by a heater, and a film 17d rotating along the outer periphery of a cylindrical guide.

After the toner image formed on the surface of the photosensitive drum 12b is transferred to the recording sheet P by the transfer roller 12c, the recording sheet P is conveyed to the heat fixing device 17, where the toner image is fixed. The sheet is discharged from the discharge port 23 by the discharge roller pair 13 through the discharge roller pair 18 and the guide section 20, and is discharged and stacked on the recording sheet discharge table 2b and the recording paper discharge tray 10 with the image side down (face down). It has become so.

A flapper 19 for switching the discharge direction of the recording sheet P is provided downstream of the discharge roller pair 18.
Is provided.

By switching the flapper 19 to the lower discharge direction, the recording sheet P can be discharged straight with the image surface up (face-up) by the discharge roller pair 18.

The recording paper feeder 15 is provided at the rear of the apparatus main body 1.

When the recording sheet P stored in the recording paper feeding device 15 receives the recording paper feeding signal, the middle plate 15b pushes the recording paper toward the front side around the fulcrum by a pressing member (not shown). The recording sheet P rotates and the recording sheet P in front of the recording sheet P is pressed against the recording sheet separation roller 14c.

Then, the recording paper separating roller 14c is driven, and the recording paper separating roller 14c and the separating pad 14a are separated one by one by a friction piece separating action, and are pressed against the conveying roller 16a and the conveying roller 16a. Roller 1
The sheet is conveyed to the image forming unit 12 by 6c.

Further, the leading end of the recording sheet P being transported is detected by a registration sensor (not shown) provided downstream of the transport roller 16a.

On the other hand, in the recording system 4, the image output timing is adjusted so that the leading edge of the toner image formed on the photosensitive drum 12b coincides with the leading edge of the recording sheet P.
The image is transferred to a correct position on the surface of the recording sheet P conveyed to the nip between the transfer roller 12c and the photosensitive drum 12b.

The image is recorded on the front side of the recording sheet P stacked on the recording paper feeding device 15.

The recording sheet P has a side regulating plate 15 movably mounted in accordance with the size of the recording sheet P.
The side edge of the recording sheet P is regulated by c so that skewing does not occur. In the example shown in the figure,
The size of the recording sheet P that can be accommodated in the recording paper feeding device 15 is three types of A4 size, letter size and legal size, and the number is about 100 sheets.

A cartridge cover 2 is provided on the apparatus main body 1 so as to be openable and closable.
It can be pulled out and replaced.

The apparatus main body 1 is provided with an interlock switch (not shown),
The recording system 4 is not operated when the cartridge cover 2 is opened.

The laser scanner unit 11 is provided with a laser shutter (not shown) that opens and closes in conjunction with the opening and closing of the cartridge cover 2 to prevent laser light from entering the operator's eyes when the cartridge cover 2 is opened. In.

If a jam of the recording sheet P occurs during recording, the recording sheet P staying inside can be taken out by opening the cartridge cover 2.

Next, a control system of an image reading apparatus (facsimile apparatus) showing features of the embodiment of the present invention will be described with reference to a block diagram shown in FIG.

In FIG. 3, reference numeral 21 denotes a facsimile control unit, which includes a power supply unit 21b for supplying power to the entire apparatus, a modem board unit, and an NC for connecting a telephone.
U board unit 21e, display unit for displaying the contents input from operation unit 21c, etc., and printer interface 21f1 for obtaining data from peripheral computers
Etc. are arranged.

The control unit 21 controls the entire device.
PU 21a1, ROM 21a2 storing various programs and various data, etc., RAM 21a3 used as a work area of CPU 21a1 and temporarily storing various data such as the number of recordings, and input / output switching for separating between facsimile and printer It has an interface 21a7 and the like.

Reference numeral 21a4 denotes a line memory for storing an image of each line of image data. In the case of transmitting or copying a document, one line of image data from the document reading system 3 is stored. In the case of reception, the decoded data for one line is stored.

Then, the image data stored in the line memory 21a4 passes through the CPU 21a1, adds a recording system control code, and is output from the input / output switching interface 21a7 to the CPU B1 of the recording system 4, and the CPU B1 transmits the recording system control code. By decoding, image recording is performed.

The reference numeral 21a5 designates the image information to be transmitted as MH
An encoding / decoding unit that encodes by encoding or the like, or that decodes received encoded image data and converts it into image data.

Reference numeral 21a6 denotes a buffer memory for storing coded image data transmitted and received. Next, control of the print function will be described.

First, data and a recording system control code are sent from the peripheral computer to the printer interface 21f1.
It is taken into this device.

The input / output switching interface 21
a7 to the CPU B1 of the recording system 4,
Print recording is performed by the UB 1 decoding the recording system control code.

At this time, the CPU 21a of the control unit 21
1 is configured not to control the print record.

This simplifies the separation between the facsimile and the printer. Next, the reading operation according to the embodiment of the present invention will be described in detail with reference to FIG.

When the user sets a plurality of documents D on the document tray 9 and the document table 2a, the leading end of the document pushes up the DS lever 25a for detecting the presence or absence of the document.
The apparatus recognizes that the original has been set by the DS sensor 25b which is a transmission sensor.

Then, the motor (not shown) rotates, and the separation roller 3c against which the original D is pressed by the preliminary pressing arm 3a rotates in the direction of the arrow, and stops once the motor rotates by a predetermined number of rotation steps.

When reading of a document is started by a subsequent operation, the set document D is separated and conveyed one by one by a friction piece 3b and a separation roller 3c.

The leading edge of the conveyed document rotates the DES lever 26a for detecting the leading edge of the document, and the leading edge of the document is recognized by the DES sensor 26b which is a transmission type sensor.

When the leading edge of the document reaches the transport roller 3e,
The conveying speed of the conveying roller 3e is higher than that of the separating roller 3c, and the one-way clutch is mounted on the shaft of the separating roller 3c, so that the separating roller 3c itself rotates.

Therefore, the subsequent document transport is performed by the transport roller 3d pressed by a pressing spring (not shown) and the transport roller 3e pressed against the transport roller 3d.

The conveyance force of the document is calculated by the difference (F1) between the force (F1) by the conveyance roller 3e and the load force (F2) by the friction piece 3b.
1-F2), there is a difference between F1 and F2 depending on the document, and in particular, F2 greatly differs depending on the type of the document.

The feed amount from the detection of the leading edge of the document by the DES sensor 26b to the reading position is determined in advance by design and experiment.

When the leading edge of the document is detected by the DES sensor 26b, reading is started after the document is conveyed by a predetermined feed amount.

By doing so, reading from the leading edge of the original can be started with high accuracy.

In the actual machine, in order to avoid reading the shadow at the leading edge of the document, the reading is set to start from a position slightly entering from the leading edge of the document.

When reading of one line is completed, the operation of transporting the original by one line is repeated up to the trailing end of the original.

At the position of the DES lever, the rear end of the original is the DES lever 26a and the DES sensor 26
b.

Since the feed amount for conveying the rear end of the original to the reading position after the detection of the rear end of the original by the DES sensor 26b is determined in advance by design and experiment, the reading operation to the rear end of the original is performed. Can be continued.

In this way, the entire original can be read from the front end to the rear end of the original.

Thereafter, the document D is discharged out of the apparatus by a discharge roller 3f pressed by a pressing spring and a discharge roller 3g pressed against the discharge roller 3f.

Since the DES lever 26a detects the leading edge and the trailing edge of the document, the length of the document including the image expansion when the reading device actually conveys the document can be detected (D
The ES lever 26a functions as detecting means for detecting the length of the sheet to be conveyed in the conveying direction).

Next, control for converting the image actually read according to the document length of the document D read by the reading device (magnification correction of the read image by magnification correction means to obtain read image data) The reading control will be described with reference to the flowchart of FIG.

(1) The original lengths of some standard papers are set in advance (the set original length is the length of the sheet in the conveying direction recognized in advance).

(2) Since the DES sensor 26b can detect the leading edge and the trailing edge of the original, the apparent original length l0 (length based on the detection result of the detecting means) in the reading device is obtained.

(3) A magnification, which is a ratio between a preset A4 size original length and an apparent original length l0, is obtained.

(4) The magnification obtained in (3) is from 95% to 1
Check if it is within the range of 05%.

(5) If not within the range, a magnification which is a ratio of a preset letter size document length to an apparent document length l0 is determined.

(6) The magnification obtained in (5) is from 95% to 1
Check if it is within the range of 05%.

(7) If the original length is not within the range, a magnification which is a ratio of a preset liga size original length to an apparent original length l0 is obtained.

(8) The magnification obtained in (7) is from 95% to 1
Check if it is within the range of 05%.

If the original document is not within the range, it indicates that the original document is in an abnormal operation such as a paper jam and abnormal image elongation, or that the original document was not of a standard size.

In this case, it is inappropriate to correct the magnification (i.e., if the original sheet having a non-standard size is regarded as having a standard size, and the magnification is enlarged, the read data will be abnormally magnified). The image is used as it is as a read image.

However, when the length of the read image is within ± 5% of the preset document length, that is, in the cases of (4), (6), and (8), the above-mentioned case is described. As described above, the friction piece 3b for the original D
e, etc., there is a slight difference from the designed one, and even when image expansion and image contraction occur, it is determined that the operation is normal, and the read image is stopped only in the original transport direction in the above. Performs image processing to magnify at magnification.

The image-processed image is used as a read image.

In this way, the error of the sheet conveyance direction caused by the conveyance is corrected for the magnification, and the image can be read with high precision without image expansion and image shrinkage.

As described above, with respect to the actual length of the original sheet in the sheet direction, the transport error of the transport means for transporting the sheet (error such as transport delay caused by a difference in frictional force or the like by the separation means) causes the error. In addition, the read image data is obtained by correcting the magnification by the difference from the detected length in the sheet direction, thereby improving the read image quality.

As described above, the actual length of the original sheet in the sheet direction is determined based on the data based on the standard sheet that can be conveyed, and is detected by the flow chart shown in FIG. The type of the conveyed fixed form sheet can be known by sequentially comparing the length with the set length and using the closest one as a reference, and the data may be compared based on the data.

At this time, a predetermined range (95% to 105% in the above example) is set with respect to the reference value recognized in advance.
% Range), and if it is out of the range, as described above, it is determined that the document is not a fixed-size sheet or the like. It becomes possible.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention. In the first embodiment, the configuration in which the magnification is corrected by comparing the detected length with the detected length based on the document length set in advance has been described. However, the present invention is not limited to the preset values, and may be based on a value input by a user. In the present embodiment, such an example will be described. Since the overall configuration and the like are the same as those of the first embodiment, the description thereof will be omitted, and only the characteristic control unit will be described.

In the first embodiment, when the document length that can be recognized when reading the document is within a certain range, the length is adjusted to the length of the standard paper.
The case where the read image is directly used as the read image has been described.

However, when a reading system is considered as an image input device, a photograph is often used as a document.

The length of the photograph in the transport direction differs depending on the size of the printing paper, and the length in the transport direction differs depending on whether the original is fed vertically or horizontally.

The frictional force (F1) of the front surface of the photographic paper against the transport roller 3e and the frictional force (F2) of the rear surface of the photographic paper against the separation piece 3b are significantly different from those of general paper.

An embodiment of the present invention in such a case will be described with reference to the flowchart of FIG.

(1) The user inputs a document length (L) by key before reading the document.

(2) Thereafter, the reading operation of the document is started. Then, similarly to the first embodiment, the original length l0 as viewed from the reading device by the DES sensor in the reading device.
Can be recognized.

Normally, when a photo original is read, l0> L, and the picture is extended by (10-L) as a whole image.

(3) After the reading of the image for one page is completed, only the original conveyance direction of the read image is magnified L / 10 times and used as the read image.

By doing so, the original document length which was actually read as l0 can be returned to the original document length (L) by image processing, and an accurate image reading without image expansion and image shrinkage can be performed. Becomes possible.

In the above description, the case of a photograph has been described. However, it is needless to say that the present invention can be applied to a case where a sheet of a size other than the standard size is used as a document.

(Third Embodiment) FIGS. 7 to 9 show a third embodiment of the present invention. In the present embodiment, the separation function of the separation unit can be made to function or the separation function can be canceled. When the separation function is canceled, the read image is directly read and the separation function is read. In the case where is operated, the configuration is such that the read image is read after correcting the magnification.

Since the overall configuration is the same as that of the above-described embodiment, the description thereof will be omitted, and only the characteristic components will be described.

In each of the above-described embodiments, the document separation device called the ADF, which is composed of the friction piece 3b and the separation roller 3c, always operates.

As described above, the load due to the friction between the back surface of the document and the separation piece has a great effect on the expansion and contraction of the image.

By the way, in the case of paper which is usually used as plain paper, it is convenient to use the ADF because the apparatus automatically separates and feeds the paper one by one.

However, in the case of reading a document that is not properly conveyed with thick paper or the like or a document that the user does not want to scratch the surface of the document, such as a photograph, it may be more convenient not to use the ADF. For this reason, a document reading system has been devised in which the ADF is activated or deactivated according to the use situation.

FIGS. 8 and 9 show a mechanism for operating or releasing the document separating function.

More specifically, when the document release lever 28 as a selection means is rotated about the rotation center provided on the upper guide 24 (FIG. 9), a part of the document release lever 28 is placed under the ADF holder 27a. Get in.

Then, the ADF holder 27a is pushed up against the force of the ADF spring 27b, and a gap is formed between the friction piece 3b and the separation roller 3c (FIG. 8). It is possible to construct a system that has been set.

In this system, since there is no load due to friction between the back surface of the document and the friction piece 3b, the speed at which the document is transported
It is almost equal to the peripheral speed of e.

On the other hand, in the system in which the above-mentioned ADF is acted,
Since the friction piece 3b hits the back side of the document, even if special paper is not used as the document, the load is applied to the conveyance of the document, and a slight slip occurs with respect to the conveyance of the conveyance roller 3e. It grows slightly.

For this reason, it has been difficult to satisfy both cases where the ADF is released with respect to the standard value where the expansion / contraction is 1% or less with respect to the document length, and where the ADF is not released.

An embodiment of the present invention as a solution to this problem will be described with reference to the flowchart of FIG.

The diameter of the conveyance roller 3e is
It is determined that there is almost no image expansion and image shrinkage in a state where 8 is released.

It is experimentally determined in advance how much image elongation (elongation rate) occurs when plain paper, which is a commonly used paper, is used as an original in a state where the original release lever 28 is not released. It has been demanded.

When the reading of the document is started, the position of the document release lever is detected by the lever sensor 29 to determine whether the document release lever 28 is released or not (1).

When the document release lever 28 is released, the reading operation of the document is actually started, and the read image is used as the read image (4).

On the other hand, even when the document release lever 28 is not released, the reading operation of the document is started (2), but the read image is magnified only in the document conveying direction by using the above-described elongation ratio, The image is read (3).

By controlling the read image in this way, the post-processing image processing is performed according to the type of the original, the case where the ADF is canceled according to the usability, and the case where the ADF is operated, thereby increasing the image expansion. In addition, it is possible to achieve both high-precision image reading without image shrinkage and improvement in usability.

(Fourth Embodiment) In the above configuration, when paper is fed using the separating function of the separating means,
After the trailing end of the paper has passed through the separating means, no stretch occurs in the read image.

Therefore, in the present embodiment, as shown in FIG. 10, the read image area l ₀ except the area a where the image does not expand (corresponding to the length from the separation section to the reading section). −a (FIG. 10
The magnification change is corrected only in the middle shaded area).

As a result, more accurate image information can be obtained.

More specifically, a in FIG.
This is the distance from the ADF to the reading point and is known in advance experimentally and in design. This range is the same as the conveyance when the ADF is released.

In the hatched portion in FIG. 10, there is a possibility that the image is extended by the ADF.

Therefore, focusing only on this range, l ₀ −
a is compared with L (N) -a (L (N) is the actual length of the paper), and scaling is performed only in the range of the hatched portion.

[0144]

As described above, according to the present invention, the image read by the reading means is read as read image data by correcting the error in the sheet conveying direction by the magnification correction means. Therefore, even if a conveyance error due to sheet conveyance occurs due to a difference in the type of sheet, etc.,
Appropriate read image data is obtained, and the read image quality is improved.

Correction of the error between the length of the sheet to be conveyed in the conveyance direction detected by the detection means and the previously recognized length of the sheet in the conveyance direction is corrected by the magnification correction means to correct reading. Image data can be obtained.

By setting and recognizing the length of a fixed sheet that can be conveyed in the conveyance direction in advance, it can be used as a reference for comparing errors, and the conveyance of a sheet having a plurality of detected lengths set. By using the closest length among the lengths in the direction as a comparison reference, appropriate read image data can be obtained.

Further, if the magnification correction is performed by the magnification correcting means only when the detected length is within a predetermined range with respect to the length of the recognized sheet in the conveying direction, the recognized length can be obtained. If the length of the sheet in the transport direction is not appropriate as a reference, unnecessary magnification correction can be prevented. It is appropriate that the predetermined range is 95% or more and 105% or less with respect to the length of the recognized sheet in the transport direction.

Further, if the length of the sheet in the conveying direction is recognized in advance by a user's input, an appropriate magnification correction can be performed even if the length is not set, for example, a sheet other than a standard sheet. And the quality of the read image is improved.

If the magnification correction is made by the magnification correcting means only when feeding while using the separating function of the separating means for separating and feeding a plurality of stacked sheets one by one, the separating function will not function. In such a case, normally, the magnification correction is not necessary, so that processing according to the situation can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration perspective view of an entire image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration sectional view of the entire image reading apparatus according to the embodiment of the present invention;

FIG. 3 is an explanatory block diagram of recording control of the image reading apparatus according to the embodiment of the present invention;

FIG. 4 is a detailed view of a document separating unit of the image reading apparatus according to the embodiment of the present invention.

FIG. 5 is a flowchart showing control for converting an image actually read by the image reading apparatus according to the embodiment of the present invention;

FIG. 6 is a flowchart illustrating image processing control of an image reading apparatus according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing image processing control of an image reading apparatus according to a third embodiment of the present invention.

FIG. 8 is a schematic configuration sectional view illustrating a mechanism of a document separation unit of an image reading apparatus according to a third embodiment of the present invention.

FIG. 9 is a schematic configuration plan view illustrating a mechanism of a document separation unit of an image reading device according to a third embodiment of the present invention.

FIG. 10 is an explanatory diagram of an image reading device according to a fourth embodiment of the present invention.

FIG. 11 is an explanatory sectional view of a facsimile apparatus according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Cartridge cover 2a Document mounting table 2b Recording sheet discharge table 2c Slider 3 Optical reading system 3a Preliminary pressure contact arm 3b Friction piece 3c Separation roller 3d Transport roller 3e Transport roller 3f Discharge roller 3g Discharge roller 4 Recording system 5 Operation panel 6 Document holding plate 7 Contact image sensor 8 Recording paper feed tray 9 Document tray 10 Recording paper discharge tray 11 Laser scanner unit 11a Polygon mirror 11b Folding mirror 12 Image forming unit 12a Recording cartridge 12b Photoconductor drum 12c Transfer roller 12d Primary charging Roller 12e Developing roller 12f Toner tank 13, 18 Discharge roller pair 14a Separation pad 14c Recording paper separation roller 15 Recording paper feeding device 15b Middle plate 15c Side regulating plate 16a Transport roller 16c Roller 17 Fuser 17a heater 17b pressing roller 19 flapper 20 guides 23 discharge port 24 upper guide 25a DS lever 25b DS sensor 26a DES lever 26b DES sensors 27a ADF holder 27b ADF spring 28 original release lever D document P recording sheet

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C062 AA02 AB02 AB30 AB31 AB32 AB41 AC11 AC66 AC67 AC68 AC69 AF10 BA00 5C072 AA01 BA17 LA18 NA01 RA04 UA13 5C076 AA21 AA22 BA01 BA03 BB24 CA10 CB04

Claims (9)

[Claims] An image reading apparatus provided with a reading unit for reading an image on a sheet to be conveyed, wherein the image read by the reading unit is read as read image data by correcting a magnification of an error in a sheet conveying direction. An image reading apparatus comprising a magnification correction unit. A detecting means for detecting a length of the sheet to be conveyed in the conveying direction, wherein an error between a length based on a detection result of the detecting means and a previously recognized length of the sheet in the conveying direction is calculated. 2. The image reading apparatus according to claim 1, wherein the magnification correction unit corrects the magnification. 3. The image reading apparatus according to claim 2, wherein the length of the fixed form sheet that can be conveyed is set in advance and recognized. 4. A length based on a detection result of said detection means,
4. The image reading apparatus according to claim 3, wherein an error between the length and the closest length among a plurality of lengths of the sheet in the conveying direction is corrected by the magnification correcting unit. 5. The length based on the detection result of said detecting means is:
5. The image reading apparatus according to claim 2, wherein the magnification correcting unit corrects the magnification only when the length of the recognized sheet in the conveying direction is within a predetermined range. 6. The image reading apparatus according to claim 5, wherein the predetermined range is a range of 95% or more and 105% or less with respect to a length of the recognized sheet in the transport direction. 7. The image reading apparatus according to claim 2, wherein the length of the sheet in the conveying direction is recognized in advance by a user input. 8. Separating means for separating and feeding a plurality of stacked sheets one by one, and feeding the sheet while using the separating function of the separating means, or canceling the separating function and using the separating means without using the separating means. 8. A method according to claim 1, further comprising selecting means for selecting whether to perform feeding, wherein the magnification correction is performed by the magnification correcting means only when feeding is performed while using the separating function of the separating means. The image reading device according to any one of the above. 9. The variable magnification correction means performs magnification correction only in a range where a load is applied in the transport direction by the separation function only when feeding is performed while using the separation function of the separation means. The image reading device according to claim 8.