JP2004120425A - Original reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original reader that is prevented from deviating in original reading timing. <P>SOLUTION: An identification image is drawn with a prescribed pattern on the bottom face of an original pressing plate 5. When image data read by an image reading part 2 are switched from the identification image data to different image data, it is detected that the front edge of the original is located at a reading position 6, and when different image data are switched to the identification image data, it is detected that the rear edge of the original is located at the reading position 6. The original image is read (image data area is separated) in accordance with the timing of detecting the front and rear edges of the original. This prevents the original image reading timing from deviating due to the sliding of a registration roller at carrying the original. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a document reading apparatus which is applied to an image forming apparatus such as a digital copying machine and reads an image of a document.
[0002]
[Prior art]
2. Description of the Related Art Some image forming apparatuses such as digital copiers have a so-called sheet-through system that can read an image at a reading position while moving one or more documents set on a document tray one by one. Some include a document reading device.
The document reading apparatus includes a document conveying path for guiding a document from a document tray to a reading position, and a registration roller for sending the document to the reading position at a constant speed. A sensor (registration sensor) for detecting the leading edge and the trailing edge of the document is arranged near the registration roller so that the document reaches the reading position at a predetermined timing by the registration roller (for example, see Patent Document 1). ).
[0003]
[Patent Document 1]
JP 2001-160887 A
[0004]
[Problems to be solved by the invention]
However, in the above-described related art, there is a case where a shift occurs in the reading timing of the document due to slippage of the registration roller when the document is transported.
In addition, there is a problem that the cost is increased by the necessity of providing a resist sensor.
The present invention has been made under such a background, and an object of the present invention is to provide a document reading apparatus in which there is no deviation in document reading timing.
[0005]
Another object of the present invention is to provide a document reading apparatus with reduced cost.
[0006]
Means for Solving the Problems and Effects of the Invention
According to the first aspect of the present invention, there is provided a document feeder (32) for moving a document at a constant speed in a movement path (31), and a document feeder provided in the movement path for moving the document. A document reading position (6) extending in the document width direction (main scanning direction) intersecting the document scanning direction and continuously facing from the leading end to the trailing end in the moving direction of the document; When a document is not opposed to the reading position, an identification image display unit (5) for displaying an identification image facing the document reading position, and reading means (2) for reading an image facing the reading position. ) And when the image read by the reading means changes from a state matching the identification image to a mismatching state, and a case changing from the mismatching state to a matching state, respectively, is determined as the leading end and the trailing end of the document, respectively. The discrimination signal Force determining means (50, 54, S6, S8) is a document reading apparatus characterized by comprising (1).
[0007]
It should be noted that the alphanumeric characters in parentheses indicate corresponding components and the like in embodiments described later. Hereinafter, the same applies in this section.
According to this configuration, when the image read by the reading unit changes from the state matching the identification image to the mismatching state, and when the state changes from the mismatching state to the matching state, the leading end and the trailing end of the document are detected. Therefore, if the image of the document is read in accordance with the timing of detecting the leading edge and the trailing edge of the document, the timing of the image reading of the document may be deviated due to slippage of the registration rollers during document transport. There is no such thing.
[0008]
Further, since the leading and trailing edges of the document are detected by the discriminating means, there is no need to provide a registration sensor, and the cost can be reduced.
If the identification image display section is provided in the document holding section (5) for restricting the document from being separated from the document reading position (6), it is necessary to provide another member as the identification image display section. Cost can be reduced.
In response to the discrimination signal of the leading edge of the document being output from the discriminating means (50, 54, S6, S8), the read signal of the reading means (2) is image-formed. Signal processing means (50) for stopping output of the read signal of the reading means for image formation in response to the determination signal of the rear end of the document being output from the determination means. , 55), it is possible to take out only the image of the document from the image read by the reading means.
[0009]
According to the third aspect of the present invention, the document reading position (6) includes a transparent plate (4) on one side of which the document and the identification image display section (5) can face, and the reading means (2). May read an image from the other surface side of the transparent plate.
Also, as in the invention according to claim 4, the identification image display section (5) is always opposed to one surface of the transparent plate (4), and the document is placed on one side of the transparent plate and the identification surface. You may be made to be able to move between an image display part.
[0010]
According to a fifth aspect of the present invention, there is provided a reference data storage means (56) for previously storing reference data of the identification image, data of the identification image read by the reading means (2), and the reference data storage means. The difference identification means (50, 52, S3) for identifying a difference from the reference data, and the identification image display section (5) or the transparent plate (50) when the difference is identified by the difference identification means. The document reading apparatus (1) according to claim 3, further comprising a dirt determining means (50, 53, T5) for determining whether or not there is dirt in (4).
[0011]
According to this configuration, it is possible to determine whether or not the transparent plate or the identification image display portion is dirty based on the recognition result of the difference recognition unit. Dirt can be removed.
As in the invention according to claim 6, the dirt determining means (50, 53, T5), when the original moves at the original reading position (6), the image of the different part is read by the reading means (2). When reading is performed (in this case, it can be determined that the dirt is on the reading unit side with respect to the document), the transparent plate (4) may be determined to be dirty.
[0012]
Further, as in the seventh aspect of the present invention, when the original moves at the original reading position (6), the dirt determining means (50, 53, T5) uses the reading means (2) to detect the difference. When the image is not read (in this case, since the dirt is on the opposite side of the reading unit with respect to the document, it can be determined that the reading of the dirt is blocked by the document.
) May determine that the identification image display section (5) is dirty.
As in the invention according to claim 8, when the dirt determining means (50, 53, T5) determines that the transparent plate (4) or the identification image display section (5) has dirt, the fact is described. If the configuration further includes the dirt notifying means (50, 8, T6, T9) for notifying the dirt, the dirt can be removed based on the notification by the dirt notifying means.
[0013]
The dirt notification means (50, 53, T5) performs notification in a different manner when the transparent plate (4) is dirty and when the identification image display section (5) is dirty. Is preferred.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a schematic sectional view showing an internal configuration of a document reading apparatus 1 according to an embodiment of the present invention. The document reading device 1 is applied to, for example, a digital copying machine, and a toner image based on image data of a document read by the document reading device 1 is transferred to a sheet to copy a document image onto a sheet (image formation). ) Is achieved.
[0015]
That is, the image data of the original read by the original reading device 1 is sent to a laser scanning unit (LSU), and the surface of the photoconductor uniformly charged by the main charger by the irradiation light from the laser scanning unit. An electrostatic latent image is formed on the image. A toner is selectively adhered to the surface of the photoreceptor on which the electrostatic latent image is formed by a developing device, and the toner image formed on the surface of the photoreceptor is transferred to a sheet by a transfer device. The sheet after the transfer of the toner image is sent to a fixing device, subjected to a predetermined fixing process, and then discharged outside the apparatus.
[0016]
The original reading apparatus 1 includes a light source 21 for irradiating light toward the original, a CCD line sensor 22 for detecting reflected light from the original and converting the reflected light into an electric signal, And first, second, and third reflecting mirrors 231, 232, and 233 for reflecting the reflected light from the CCD and guiding the reflected light to the detection surface of the CCD line sensor 22. The light source 21, the CCD line sensor 22, and the reflecting mirrors 231 to 233 constitute an image reading unit 2 for reading an image of a document.
[0017]
The irradiation light from the light source 21 is reflected by the first reflecting mirror 231 and travels upward. The document moves above the image reading unit 2 so that the image faces the image reading unit 2, and the irradiation light reflected by the first reflecting mirror 231 is irradiated from below onto the document. The light reflected by the document is reflected by the second reflecting mirror 232, then by the third reflecting mirror 233, and is incident on the detection surface of the CCD line sensor 22. The main scanning of the document in the image reading unit 2 is achieved by the electrical scanning of the CCD line sensor 22.
[0018]
The document is set on a document tray (not shown). One or a plurality of documents set on the document tray are supplied to the image reading unit 2 one by one through a document conveying path 31. The document conveying path 31 is provided with a registration roller 32 for sending out the document at a constant speed. In this embodiment, a registration sensor (a sensor for detecting the leading edge and the trailing edge of a document) is not provided near the registration roller 32 as in a conventional document reading apparatus. The document tray, the document conveying path 31 and the registration roller 32 constitute a document supply unit 3 for supplying a document to the image reading unit 2.
[0019]
Above the image reading unit 2, a transparent contact glass 4 is arranged. The upper surface of the contact glass 4 extends in the main scanning direction (original width direction), and is continuously opposed from the leading end to the trailing end by moving the original by the original supply unit 3. The reading position 6 is set. The document reading device 1 is a so-called sheet-through type document reading device capable of reading an image at a reading position 6 while moving the documents one by one by a document supply unit 3. By moving upward, sub-scanning of the document is achieved.
[0020]
The reading position 6 may have a width of one line of the read pixels of the CCD line sensor 22 in the sub-scanning direction, or may have a width of a plurality of lines.
The image reading unit 2 can read the image of the document by not only reading the image of the sheet-through document but also placing the documents one by one on the contact glass 4. Is also good. In this case, the sub-scanning of the document may be achieved by the relative movement of the light source 21 and the reflecting mirrors 231 to 233 with respect to the document.
[0021]
A document pressing plate 5 for restricting a document passing above the reading position 6 from being separated from the reading position 6 is provided above the contact glass 4 at a predetermined distance from the upper surface of the contact glass 4. (As much as possible). The document supplied by the document supply unit 3 moves between the document pressing plate 5 and the contact glass 4.
In this embodiment, an identification image is drawn in a predetermined pattern on the lower surface of the original pressing plate 5. When the image is read by the image reading unit 2 in a state where there is no original at the reading position 6, the identification is performed. Images are read.
[0022]
FIG. 2 is a diagram showing a pattern of an identification image drawn on the document pressing plate 5 and a monochrome level based on an electric signal output from the CCD line sensor 22 when the identification image is read.
On the lower surface of the document pressing plate 5, for example, an identification image whose color pattern is switched along the main scanning direction (perpendicular to the paper surface in FIG. 1) is drawn. Specifically, the lower surface of the substantially white document pressing plate 5 is filled with a plurality of colors (for example, blue and yellow) at predetermined intervals along the main scanning direction.
[0023]
When the identification image is read by the image reading unit 2, the monochrome level based on the electric signal output from the CCD line sensor 22 switches in a predetermined pattern along the main scanning direction. In other words, the black and white level of the part painted blue in the identification image is higher than the black and white level of the part painted yellow.
The identification image is not limited to the one in which the color pattern is switched along the main scanning direction as in this embodiment as long as the image can be distinguished from the image of the original, and may be, for example, a bar code. Or a specific pattern.
[0024]
However, if the density of the identification image is low, the black and white level of the identification image becomes close to the black and white level of blank paper (paper on which nothing is recorded). There is a possibility that the image cannot be distinguished. If the density of the identification image is high, there is a possibility that the identification image may be read by the image reading unit 2 through the document even though the document exists at the reading position 6. Therefore, it is preferable that the density of the identification image is set to an appropriate density such that the density of the identification image can be reliably distinguished from the image of the document and the document is not transparent.
[0025]
FIG. 3 is a block diagram showing an electrical configuration of the digital copying machine according to this embodiment.
Referring to FIG. 3, the control circuit of the digital copying machine includes a control unit 50 constituted by a microcomputer. The control unit 50 includes, for example, an operation unit 7 arranged on the upper surface of the digital copying machine and operated when starting an image forming operation in the digital copying machine or performing various settings, and a document on a document tray. A document set sensor 33 for detecting whether or not the document is set is connected.
Thus, output signals from the operation unit 7 and the document set sensor 33 are input to the control unit 50.
[0026]
Further, the control unit 50 is connected with a display unit 8 constituted by, for example, a liquid crystal display or the like as an object to be controlled. The display on the display unit 8 is controlled.
The operation unit 7 and the display unit 8 may be integrally formed as, for example, an operation panel. In this case, for example, a liquid crystal display with a touch panel may be used, and the display screen may serve as the operation unit 7 and the display unit 8.
[0027]
The image reading unit 2 is connected to the control unit 50. The electric signal output from the CCD line sensor 22 of the image reading unit 2 is input to the control unit 50 via, for example, an A / D converter (analog / digital converter). The A / D converter quantizes the analog electric signal output from the CCD line sensor 22 to generate a digital image signal.
The control unit 50 has a plurality of function processing units that are implemented by software when a microcomputer executes predetermined program processing. That is, the control unit 50 substantially includes a shading correction processing unit 51, a difference recognition unit 52, a stain determination unit 53, a document detection unit 54, and an area separation unit 55. Further, the control unit 50 includes a memory 56.
[0028]
The analog signal output from the image reading unit 2 (CCD line sensor 22) is not uniform in the main scanning direction even when an image of a document (white paper or the like) having the same density on the entire surface is read. This is because the light source 21 has different light distribution characteristics along the main scanning direction (a characteristic in which the luminance at both ends in the main scanning direction decreases), and there is a sensitivity variation among the pixels read by the CCD line sensor 22. That's why. The shading correction processing unit 51 corrects variations in image data between pixels due to the above-described characteristics of the image reading unit 2.
[0029]
In the image reading unit 2, a shading correction plate 9 is arranged near the contact glass 4 (see FIG. 1). At the time of the shading correction processing, first, the light source 21 and the reflecting mirrors 231 to 233 are moved in the sub-scanning direction to illuminate the surface (for example, white) of the shading correction plate 9 to read the image data. The reading characteristics of the image reading unit 2 are recognized by the shading correction processing unit 51 based on the. Then, the shading correction processing unit 51 performs settings based on the recognized reading characteristics so as to correct variations in image data (eg, image data of a document) read by the image reading unit 2 thereafter.
[0030]
The difference discriminating unit 52 reads the identification image data read from the document pressing plate 5 and the reference data stored in the memory 56 in advance (the identification image when the document pressing plate 5 and the contact glass 4 are read without contamination). ), The difference between the data is identified. When the different part is recognized by the difference recognition part 52, it can be determined that at least one of the document pressing plate 5 and the contact glass 4 is dirty.
[0031]
The stain determination unit 53 determines which of the document pressing plate 5 and the contact glass 4 is stained when a different part (stain) is recognized by the difference recognition unit 52. The dirt determination unit 53 reads the image of the different part recognized by the difference recognition unit 52 when the document moves on the reading position 6 (when the dirt is on the image reading unit 2 side of the document). ), It is determined that the contact glass 4 is dirty, and when the image of the different portion cannot be read (when the dirt is on the opposite side of the image reading unit 2 with respect to the document), the document pressing plate 5 is Judge as dirty.
[0032]
The document detection unit 54 detects the leading edge and the trailing edge of the document by detecting whether the image data sent from the image reading unit 2 is identification image data. That is, the document detection unit 54 switches the image data read by the image reading unit 2 from the identification image data to another image data (image data that is not the identification image data) (when the state changes from the matching state to the mismatching state). In addition, when the leading edge of the document is detected at the reading position 6, when the other image data is switched to the identification image data (when the state changes from the mismatched state to the matched state), the rear end of the document is set at the reading position 6. You can detect that there is.
[0033]
The area separating section 55 separates (area separates) image data before and after the leading and trailing ends of the document by the document detecting section 54 when the leading and trailing ends of the document are detected. That is, in response to the detection of the leading edge of the document, the area separating section 55 starts outputting a read signal (a signal indicating that the image of the document should be read) of the document reading section 2 to form an image. In response to the detection of the trailing edge of the document, the output of the read signal of the image reading section 2 for image formation is stopped, so that only the image data of the original to be formed is taken out and the memory 56 is read out. Can be stored.
[0034]
In this embodiment, the image of the document is read (separation of the image data area) in accordance with the timing of detecting the leading edge and the trailing edge of the document by the document detecting unit 54. As a result, the timing for reading the image of the document is not shifted.
Further, since the leading and trailing edges of the document are detected by the document detection unit 54, there is no need to provide a registration sensor, and the cost can be reduced.
[0035]
FIGS. 4 and 5 are flowcharts showing the contents of control by the control unit 50 when reading an image.
Referring to FIG. 4, when image forming operation is started by operating operation unit 7 with a document set on a document tray, control unit 50 first causes image reading unit 2 to set the surface of shading correction plate 9 Is read, and a shading correction process is performed (step S1). Then, the control unit 50 causes the image reading unit 2 to read an image (identification image) on the surface of the document pressing plate 5, and stores the identification image data in the memory 56 (Step S2).
[0036]
Thereafter, the control unit 50 recognizes a difference between the identification image data and the reference data (Step S3). If there is no difference between the identification image data and the reference data, that is, if neither the document holding plate 5 nor the contact glass 4 is stained (NO in step S4), the control unit 50 sets the document tray in the document tray. The first set original is supplied to the reading position 6 (step S5).
When the leading edge of the document is detected by the document detection unit 54 (YES in step S6), the control unit 50 separates the image data from the image reading unit 2 at that timing, and converts the subsequent image data to the image of the document. Read as data (step S7). If the trailing edge of the document is detected thereafter (YES in step S8), the control unit 50 separates the image data again at that timing, and replaces the image data up to that time with the image of the first document. The data is stored in the memory 56 as data.
[0037]
If it is determined based on the detection signal from the document set sensor 33 that there is still a document on the document tray (YES in step S9), the control unit 50 directs the second document to the reading position 6. The document is supplied (step S5), and the image of the document is read (steps S6 to S8). In this way, the control of steps S5 to S9 is repeated until there is no document on the document tray (until NO is obtained in step S9). When there is no document on the document tray (NO in step S9), the image of the document is read. Ends.
[0038]
On the other hand, when there is a difference between the identification image data and the reference data, that is, when at least one of the document pressing plate 5 and the contact glass 4 is dirty (YES in step S4), the control unit 50 The data of the different part (difference data) is stored in the memory 56 (step T1; see FIG. 5).
Thereafter, the control unit 50 causes the first document set on the document tray to be supplied toward the reading position 6 (step T2). When the leading edge of the document is detected by the document detection unit 54 (YES in step T3), the control unit 50 separates the image data from the image reading unit 2 at that timing and converts the subsequent image data to the image of the document. Read as data (step T4).
[0039]
If there is no difference portion based on the difference data stored in the memory 56 in step T1 in the read document image (NO in step T5), the difference portion (dirt) is determined by the image reading unit 2 on the document. Since it is on the opposite side, it can be determined that the reading of the different portion has been interrupted by the document. In this case, the control unit 50 determines that the document pressing plate 5 is dirty, and displays the fact on the display unit 8. (Step T9).
Even if the document holding plate 5 is dirty, the control does not affect the image data of the document read by the image reading unit 2 even if the document holding plate 5 is dirty. Until YES is reached; see FIG. 4), and the image reading of the first document is continued as it is. The subsequent control by the control unit 50 is the same as when there is no difference between the identification image data and the reference data (NO in step S4) (steps S5 to S9).
[0040]
On the other hand, if there is a different portion based on the difference data stored in the memory 56 in step T1 in the read document image (YES in step T5), the difference portion (dirt) is read from the image of the document. The control unit 50 can determine that the contact glass 4 is dirty, and in this case, determines that the contact glass 4 is dirty, and displays the fact on the display unit 8 (step T6).
If the contact glass 4 is dirty, the dirt is read by the image reading unit 2 as an image of the document, and it is not preferable to continue reading the image of the document as it is. In this case, the control unit 50 stops the image reading of the document by the image reading unit 2 (step T7), and once discharges the first document that has been taken halfway.
[0041]
After the dirt on the contact glass 4 is removed, the document is set on the document tray again, and when an operation for continuing the image reading in the image reading unit 2 is performed (YES in step T8), the control by the control unit 50 is performed. Returns to step S2 in FIG. 4 again, and an image (identification image) on the surface of the document pressing plate 5 is read.
The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims.
[0042]
For example, in the above embodiment, when it is determined that the contact glass 4 is dirty, the image reading of the document in the image reading unit 2 is stopped, and the first document that has been taken halfway is temporarily discharged. However, the present invention is not limited to such a configuration, and a message is displayed on the display unit 8 requesting determination of whether or not to continue reading an image of a document, and an operation of deciding to continue as it is. Is performed, the image reading of the document may be continued while the contact glass 4 is dirty.
[0043]
The configuration is not limited to the configuration in which the identification image is drawn on the surface of the document pressing plate 5, and may be a configuration in which a member on which the identification image is drawn is provided separately from the document pressing plate 5.
When it is determined that the contact glass 4 or the document holding plate 5 (identification image) is dirty, the configuration is not limited to the configuration in which the fact is displayed on the display unit 8 and, for example, a configuration in which a warning sound is issued. You may.
Although the digital copying machine has been described as an embodiment of the present invention, the present invention is not limited to the digital copying machine but can be applied to other image forming apparatuses such as a facsimile.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an internal configuration of a document reading apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a pattern of an identification image drawn on a document pressing plate and a monochrome level based on an electric signal output from a CCD line sensor when the identification image is read.
FIG. 3 is a block diagram illustrating an electrical configuration of the digital copying machine according to the embodiment;
FIG. 4 is a flowchart illustrating the control performed by a control unit when reading an image.
FIG. 5 is a flowchart illustrating the control performed by a control unit when reading an image.
[Explanation of symbols]
1 Document reading device
2 Image reading unit
4 Contact glass
5 Document holding plate
6 Reading position
8 Display
31 Document feed path
32 registration roller
50 control unit
52 Difference Certification Department
53 Soil judgment unit
54 Original detector
55 Area separation unit
56 memories

Claims (8)

Document feeding means for moving the document at a constant speed in the movement path,
A document reading position is provided in the movement path, extends in a document width direction intersecting the movement direction of the document, and is continuously moved from the front end to the rear end in the movement direction when the document is moved. ,
An identification image display unit for displaying an identification image opposite to the original reading position when the original does not face the original reading position;
Reading means for reading an image facing the reading position;
When the image read by the reading means changes from a state coinciding with the identification image to a non-coincidence state, and when the image changes from the non-coincidence state to a coincidence state, the discrimination signal is determined by respectively discriminating the leading and trailing edges of the document. A document reading device, comprising: a determination unit that outputs the document. In response to the discrimination signal of the leading edge of the document being output from the discriminating means, the output of the reading signal of the reading means for image formation is started, and the discrimination signal of the trailing edge of the document is output from the discriminating means. 2. The document reading apparatus according to claim 1, further comprising a signal processing unit that stops outputting a read signal of the reading unit for image formation in response to the image reading. The document reading position includes a transparent plate on one side of which the document and the identification image display unit can face each other,
3. The document reading apparatus according to claim 1, wherein the reading unit reads an image from the other surface of the transparent plate. The identification image display section is always opposed to one surface of the transparent plate,
4. The document reading apparatus according to claim 3, wherein the document is moved between one surface of the transparent plate and the identification image display section. Reference data storage means for storing reference data of the identification image in advance,
Data of the identification image read by the reading means, and difference recognition means for determining a difference between the reference data stored in the reference data storage means,
5. A dirt judging means for judging whether or not there is dirt on the identification image display portion or the transparent plate when the different part is judged by the difference judging means. Document reading device according to the above. The dirt determining unit is configured to determine that the transparent plate is dirty if the reading unit reads an image of the different portion when the original moves from the original reading position. 6. The document reading device according to claim 5, wherein The dirt determining unit determines that the identification image display unit is dirty if the reading unit does not read the image of the different part when the document moves to the document reading position. The document reading device according to claim 5 or 6, wherein 8. The apparatus according to claim 5, further comprising a dirt notifying means for notifying, when the dirt judging means judges that there is dirt on the transparent plate or the identification image display section, to that effect. Document reading device as described.

Images