JP2004193741A - Image scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image scanner capable of reading out a plurality of sheets of both side document in a short time under a state free from image quality deterioration. <P>SOLUTION: In case of a both side document, an automatic document carrier performs browsing and document image data is read into a memory (step S8) while correcting the document surface image data line by line based on shading correction coefficients obtained at step 3. Subsequently, an operation for reversing the document is carried out in order to read out the rear surface of the document (step 9). When the document is reversed, a CPU moves a first mirror unit beneath a reference whiteboard, reads out a line of shading correction data, and moves the first mirror unit beneath a browsing document glass (step S11) after operated shading correction coefficients are set in a coefficient memory in a shading correction circuit (step S10). In other words, when a both side document is under carriage by means of the automatic document carrier, the shading correction coefficients are updated at such a timing as the document is reversed after it is read out. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention includes an automatic document feeder capable of continuously transferring a plurality of documents, inverting the document, and enabling both sides of the document to be read, and an image for reading an image of the document transported by the document automatic feeder. Related to a reading device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a copying machine has been known as an image reading apparatus that includes an automatic document feeder and reads an image of a document transported by the automatic document feeder.
[0003]
In such a copying machine, an image of an original is read by moving and placing the original on an original platen glass of a reading device by an automatic original transporter, and then moving a mirror unit equipped with an illumination light source onto the original platen glass. Was like that.
[0004]
However, recently, in order to increase the number of documents read per unit time, a so-called drift reading method has been adopted, in which a mirror unit is fixed at a predetermined position, and a document image is read while the document is being sent to the reading device by an automatic document feeder. It is getting.
[0005]
FIG. 1 is a cross-sectional view showing the configuration of a color copying machine employing such a flow reading system.
[0006]
Referring to FIG. 1, the color copying machine mainly includes an automatic document feeder 200, an image scanner unit 201, and a printer unit 202.
[0007]
The automatic document feeder 200 feeds a document to the image scanner unit 201.
[0008]
The image scanner unit 201 reads a document and performs digital signal processing.
[0009]
Further, the printer unit 202 prints out an image corresponding to the document image read by the image scanner unit 201 on recording paper in full color.
[0010]
In the image scanner unit 201, a document 204 on a document table glass 203 is irradiated with light from a xenon tube lamp 205, reflected light from the document is guided to reflection mirrors 206 and 207, and is reflected on a three-line sensor 210 by a lens 209. It is imaged. The three-line sensor 210 extracts electric signals corresponding to the red (R) component, the green (G) component, and the blue (B) component, which are full-color information, from the reflected light, and transmits the signals to the signal processing unit 211.
[0011]
The signal processing unit 211 performs predetermined signal processing on the transmitted electric signals and outputs the processed signals to the printer unit 202. The printer unit 202 forms a copy image of the document based on this signal.
[0012]
The first mirror unit 208 having the xenon tube lamp 205 and the reflecting mirror 206 has a speed of v, and the second mirror unit 2071 having the reflecting mirror 207 has a speed of v / 2. Is driven by a motor (not shown) in the vertical direction to scan the entire surface of the document.
[0013]
In the case where the original is read by the automatic document feeder 200 using the automatic reading apparatus, the first mirror unit 208 is held below the original reading glass 14 and the original is continuously read by the automatic document feeder 200. By feeding the originals, continuous reading of the originals can be realized in a short time.
[0014]
FIG. 2 is a cross-sectional view showing the configuration of the automatic document feeder 200, and FIG. 3 is a view for explaining how the document 204 is sent by the automatic document feeder 200.
[0015]
3, when the original 204 is placed on the original feed tray 9 and the reading operation of the original is started, the paper feed roller 8 is lowered onto the original 204 ((a)), and the uppermost sheet of the original 204 is picked up. Is conveyed to the registration roller lower part 3 and the registration roller upper part 4 by the rotation of the conveying roller 6. At the lower registration roller 3 and the upper registration roller 4, a loop is formed in the sheet, and the skew of the sheet is corrected ((b)).
[0016]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original lead 13 from separating the document 204 from the large conveying roller 1 ((c )).
[0017]
Next, the original 204 is conveyed onto the flow-reading original reading glass 14 and the surface of the original image is read. It is conveyed to 11 and below the paper discharge roller 10 ((d)).
[0018]
Next, the document 204 is once conveyed onto the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 ((e)), where the upper discharge roller 11 and the lower discharge roller 10 are rotated in reverse. As a result, the document 204 is transported to the roller 2 in an inverted state ((f)). In the roller 2, a loop is formed again to correct the skew of the sheet ((g)).
[0019]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original roller 13 from separating the document 204 from the large conveying roller 1 ((h )). Next, the original 204 is conveyed onto the flow-reading original reading glass 14, and the back side of the original image is read. It is conveyed to 11 and below the paper discharge roller 10 ((i)). Then, the document 204 is once conveyed onto the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10. ((J)).
[0020]
At this point, the original is placed on the original feed tray 9 and turned over, so that the discharged original is oriented in the same direction as when the original is placed on the original feed tray 9. Then, in order to further reverse the original, the upper and lower discharge rollers 11 and 10 are reversely rotated, whereby the original 204 is conveyed to the roller 2 in an inverted state ((k)). In the roller 2, a loop is formed again to correct the skew of the sheet ((l)).
[0021]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original 13 from separating the document 204 from the large conveying roller 1 ((m )). Then, the document 204 is conveyed onto the flow-reading document reading glass 14, and is conveyed to the upper discharge roller 11 and the lower discharge roller 10 while preventing separation from the large conveyance roller 1 by the large lead roller 12 ((n )), The paper is discharged to the paper discharge tray 15 by the upper paper discharge roller 11 and the lower paper discharge roller 10 ((o)).
[0022]
When reading a plurality of originals, the operations (a) to (o) are repeated until the originals placed on the original feed tray 9 are exhausted.
[0023]
Here, the roller 2, the small lead roller 13 and the large lead roller 12 are pressed against the large transfer roller 1 with a predetermined pressure by a spring (not shown).
[0024]
The transport roller large 1 is pressed against the flow-reading document reading glass 14 with a predetermined pressure by a spring (not shown) so as to absorb a shock when the document 204 collides with the flow-reading document reading glass 14.
[0025]
Here, the case where one document is read has been described. However, when reading a plurality of documents continuously, the same operation is continuously repeated with a predetermined interval between each document conveyance.
[0026]
Also, when the original is read by the flowing reading method, the original is continuously read in a short time, so that the reading of the standard white plate for the well-known shading correction is performed only before reading the first original, Until the entire document 204 placed on the document feeding tray 9 is read, the shading correction coefficient created based on the read data is continuously used.
[0027]
Further, in order to increase the number of originals that can be read per unit time, the speed at which the original is scanned by a CCD (Charged Coupled Device) line sensor or the like is increased. In the CCD line sensor, since the speed of scanning the document and the output signal level are inversely proportional, it is necessary to increase the light amount of the light source for irradiating the document in order to prevent the image quality from deteriorating even if the document reading speed is increased.
[0028]
[Problems to be solved by the invention]
However, when reading a two-sided original in the above-described conventional image reading apparatus, the operation of inverting the original for one original is required twice as described above. When many documents are scanned, the time required to read all the documents becomes very long, and the fluctuation of the light amount of the light source illuminating the documents becomes a non-negligible level, deteriorating the image quality of the scanned documents. There was a disadvantage that it would.
[0029]
Furthermore, in order to increase the number of screen documents read per unit time without deteriorating the image quality, the amount of light of the light source for irradiating the document must be increased. However, there is a drawback that the emission spectrum of the CCD line sensor fluctuates, the temperature of the entire apparatus rises, and the sensitivity characteristic of the CCD line sensor fluctuates.
[0030]
The present invention has been made in view of these points, and an object of the present invention is to provide an image reading apparatus capable of reading a plurality of double-sided originals in a short time without deterioration in image quality.
[0031]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, an automatic document feeder for continuously transferring a plurality of documents, inverting the documents, and enabling both sides of the documents to be read, and illuminating the documents. Illuminating means, photoelectric conversion means for converting a document image into an electric signal for each line, and optical means for forming reflected light of the document on the photoelectric conversion means, wherein the document is transported by the document automatic feeding means. In the image reading device to be read, a calculating means for calculating a shading correction coefficient based on read data obtained by reading a reference white board by the photoelectric conversion means, and the shading correction coefficient calculated by the calculating means, the lighting means, A shading correction unit for correcting non-uniformity of at least one of the photoelectric conversion unit and the optical unit for each pixel; In the case of double-sided reading, when the document is inverted by the document automatic feeding means, a new shading correction coefficient is calculated by the calculation means, and the shading correction coefficient used by the shading correction means is replaced by the new shading correction coefficient. Updating means for updating with a correction coefficient.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0033]
In the present embodiment, a copying machine is shown as an application example of the present invention. However, the present invention is not limited to this, and it goes without saying that the present invention can be applied to various other apparatuses.
[0034]
(First Embodiment)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus according to a first embodiment of the present invention. As described above, the present invention is applied to a color copying machine.
[0035]
In FIG. 1, the image reading apparatus according to the present embodiment mainly includes an automatic document feeder 200, an image scanner unit 201, and a printer unit 202.
[0036]
The automatic document feeder 200 feeds a document to the image scanner unit 201.
[0037]
The image scanner unit 201 reads a document and performs digital signal processing.
[0038]
Further, the printer unit 202 prints out an image corresponding to the document image read by the image scanner unit 201 on recording paper in full color.
[0039]
In the image scanner unit 201, a document 204 on a document table glass (hereinafter, referred to as “platen”) 203 is irradiated with light from a xenon tube lamp 205, and reflected light from the document is guided to reflection mirrors 206 and 207, 209 forms an image on the three-line sensor 210. The three-line sensor 210 extracts electric signals corresponding to the red (R) component, the green (G) component, and the blue (B) component, which are full-color information, from the reflected light, and transmits the signals to the signal processing unit 211.
[0040]
The signal processing unit 211 performs predetermined signal processing on the transmitted electric signals and outputs the processed signals to the printer unit 202. The printer unit 202 forms a copy image of the document based on this signal.
[0041]
The first mirror unit 208 having the xenon tube lamp 205 and the reflecting mirror 206 has a speed of v, and the second mirror unit 2071 having the reflecting mirror 207 has a speed of v / 2. The original is scanned by a motor (not shown) in a direction perpendicular to the main scanning direction (hereinafter referred to as a “sub-scanning direction”) to scan the entire surface of the original.
[0042]
The standard white plate 5102 is used for correction data of data read by the three-line sensor 210 when the xenon tube lamp 205 is used.
[0043]
In the case where the original is read by the automatic document feeder 200 using the automatic reading apparatus, the first mirror unit 208 is held below the original reading glass 14 and the original is continuously read by the automatic document feeder 200. By feeding the originals, continuous reading of the originals can be realized in a short time.
[0044]
The signal processing unit 211 converts the image signal read by the three-line sensor 210 into a digital signal, performs predetermined processing, and temporarily stores the converted signal in a memory (not shown). Then, in synchronization with the image forming process of the printer unit 202, an image signal decomposed into each component of magenta (M), cyan (C), yellow (Y), and black (BK) is transmitted to the printer unit 202. When the original is a monochrome image, the image signal stored in the memory in the signal processing unit 211 is digitally processed, and the black (BK) component image signal is output to the printer in synchronization with the image forming process of the printer unit 202. To the unit 202.
[0045]
Each image signal of M, C, Y, and BK transmitted from the image scanner unit 201 is transmitted to the laser driver 212. The laser driver 212 modulates and drives the semiconductor laser 213 according to the transmitted image signal. The laser beam scans on the photosensitive drum 217 via the polygon mirror 214, the f-θ lens 215, and the mirror 216.
[0046]
The rotary developing device 218 includes a magenta developing device 219, a cyan developing device 220, a yellow developing device 221, and a black developing device 222. The four developing devices 219 to 222 alternately contact the photosensitive drum 217, and are disposed on the photosensitive drum 217. The formed electrostatic latent images of M, C, Y, and BK are developed with corresponding toner.
[0047]
The transfer drum 223 wraps the paper fed from the paper cassette 224 or 225 and transfers the toner image developed on the photosensitive drum 217 to the paper.
[0048]
After the four colors of M, C, Y, and BK are sequentially transferred in this manner, the sheet passes through the fixing unit 226 and is discharged.
[0049]
FIG. 5 is a diagram showing an example of the configuration of the three-line sensor 210.
[0050]
In the figure, light receiving element arrays 210-1, 210-2, and 210-3 are for reading R, G, and B wavelength components, respectively.
[0051]
The three light receiving element arrays having different optical characteristics are monolithically formed on the same silicon chip so that the R, G, and B sensors are arranged in parallel with each other to read the same line of the document. I have.
[0052]
FIG. 6 is an enlarged view of the light receiving element row in FIG. 5 described above.
[0053]
As shown in the figure, each of the sensors 210-1 to 210-3 has a width of, for example, 10 μm per pixel in the main scanning direction. Each of the sensors 210-1 to 210-3 has 5000 pixels in the main scanning direction so that the short direction (297 mm) of an A3 document can be read at a resolution of 400 dpi. The distance between the lines of the R, G, and B sensors 210-1 to 210-3 is, for example, 80 μm, and each line is separated by eight lines for a sub-scanning resolution of 400 lpi. Further, in each of the line sensors 210-1 to 210-3, an optical filter is formed on the sensor surface in order to obtain predetermined spectral characteristics of R, G, and B.
[0054]
FIG. 7 is a block diagram illustrating a configuration of the image scanner unit 201.
[0055]
In the figure, an image signal output from a CCD 210 is input to an analog signal processing unit 4001, converted into an 8-bit digital image signal in the analog signal processing unit 4001, and then input to a shading correction unit 4002.
[0056]
FIG. 8 is a block diagram illustrating a configuration of the analog signal processing unit 4001. Here, since the processing circuits for R, G, and B are all the same, only the circuit for one color is shown.
[0057]
In the figure, an image signal output from the CCD 210 is sampled and held by a sample and hold (S / H) unit 4101 to stabilize the waveform of an analog signal. A CPU (not shown) controls the variable amplifier 4103 and the clamp circuit 4102 via the voltage control circuit 4103 so that the image signal can fully utilize the dynamic range of the A / D converter 4105. The A / D converter 4105 converts the analog image signal into, for example, an 8-bit digital image signal.
[0058]
Returning to FIG. 7, the 8-bit digital image signal is subjected to shading correction by a known shading correction method in a shading correction unit 4002. When reading shading data, the CPU stores a read signal for one line from the standard white plate 5102 in a line memory 4003 in response to a read signal from the three-line sensor 210, and stores each read signal in the line memory 4003. A shading correction coefficient for setting the pixel read data to a predetermined level, for example, 240, is obtained for each pixel, and this is stored in the coefficient memory 4005 for one line. Then, at the time of actual document reading, in synchronization with the output of each pixel by the line reading of the three-line sensor 210, the shading correction coefficient corresponding to the pixel is read from the coefficient memory 4005, and the multiplier 4007 reads the shading correction coefficient from the three-line sensor 210. Shading correction is performed by multiplying each pixel signal.
[0059]
Next, correction of the physical distance of the three-line sensor 210 will be described.
[0060]
As shown in FIG. 6, since the light receiving sections 210-1, 210-2, and 210-3 of the sensor 210 are arranged at a fixed distance, the delay elements 401 and 402 allow spatial reception in the sub-scanning direction. The deviation is corrected. More specifically, the R and G signals read earlier in the sub-scanning direction with respect to the B signal are delayed in the sub-scanning direction and superimposed on the B signal.
[0061]
A first look-up table (hereinafter, referred to as “LUT”) 4008 is for correcting the gradation of a document image reading signal. A document on which an image having a predetermined density shown in FIG. 9 is drawn is placed on the platen 203, and the document image data is read. As shown in FIG. 10, when the read level 1001 has no linearity, linearity is obtained. Therefore, the input signal is corrected by the correction curve 1002 to obtain the output 1003.
[0062]
The memory 4009 temporarily stores the image signal, and outputs the image signal in synchronization with the printer unit 202. Further, predetermined density (hereinafter, referred to as “PG”) data is output from the memory 4009, and a PG image similar to the image shown in FIG.
[0063]
The log converters 403 to 405 are each configured by a look-up table ROM, and convert a luminance signal into a density signal.
[0064]
The second LUT 4010 is a circuit similar to the first LUT 4008, and performs gradation correction of the printer unit 203.
[0065]
A PG image based on the PG data output from the memory 4009 is read by the image scanner unit 201, and the read data is compared with the PG data output from the memory 4009 to obtain linearity in the PG image. If not, as shown in FIG. 10, the input signal is corrected by the correction curve and output.
[0066]
The masking and UCR circuit 406 is a well-known circuit, and detailed description thereof is omitted. According to the input three primary color signals, Y, M, C, and BK signals for output are sequentially determined at each reading operation. , For example, 8 bits.
[0067]
Each of the above circuits is controlled by a CPU (not shown).
[0068]
The operation processing executed by the image reading apparatus configured as described above will be described below with reference to the flowchart of FIG.
[0069]
In FIG. 11, the operator sets a document on the document feed tray 9 of the automatic document feeder 200, designates whether the document is a double-sided document or a single-sided document from an operation unit (not shown) (step S1), and presses a start key. When a copying operation is started by a not-shown (step S2), a CPU (not shown) moves the first mirror unit 208 below the reference white plate 5102, reads one line of shading correction data, and calculates the data. Is set in the coefficient memory 4006 in the shading correction circuit 4002 (step S3).
[0070]
Next, the first mirror unit 208 is moved below the original glass 14 (step S4).
[0071]
Next, it is determined whether the original is a two-sided original or a one-sided original (step S5). If the original is a one-sided original, the feed roller 8 of the automatic original transport device 200 is lowered onto the original 204 (FIG. a)), the uppermost sheet of the document 204 is picked up, and the document 204 is transported to the lower registration roller 3 and the upper registration roller 4 by rotation of the transport roller 6. At the lower registration roller 3 and the upper registration roller 4, a loop is formed in the sheet, and the skew of the sheet is corrected (FIG. 3B).
[0072]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original roller 13 from separating the document 204 from the large conveying roller 1 (FIG. c)).
[0073]
Next, the original 204 is conveyed onto the original reading glass 14 and the original image is subjected to the flow reading operation. The original 204 is separated from the conveying roller 1 by the large lead roller 12 while being separated from the discharge roller. It is conveyed to 11 and below the paper discharge roller 10 (FIG. 3D). Then, the document 204 is discharged to the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 (FIG. 3E).
[0074]
At this time, the CPU reads the document image data into the memory 4009 while correcting the document image data line by line based on the shading correction coefficient obtained in step 3 (step S6).
[0075]
Next, the document flow reading operation (Steps S7 and S6) is repeated (Step S8) until there are no more documents placed on the automatic document feeder 200, and when the document has run out, the image data is read from the memory 4009 and A copy image is formed by the unit 202 (step S17), and the copy operation ends.
[0076]
On the other hand, when the original is a two-sided image, the original reading operation is performed in the automatic original feeder 200, and the original image data is corrected line by line based on the shading correction coefficient obtained in step 3 while the original image is being read. The data is read into the memory 4009 (step S8).
[0077]
Next, a reverse operation of the original is performed to read the back side of the original (step 9). The original 204 once conveyed onto the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 (FIG. 3E) is rotated by rotating the upper discharge roller 11 and the lower discharge roller 10 in reverse. The sheet is conveyed to the roller 2 in an inverted state (FIG. 3F). Here, in the roller 2, a loop is formed again and the skew of the sheet is corrected (FIG. 3G).
[0078]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original lead 13 from separating the document 204 from the large conveying roller 1 (FIG. 3). (H)).
[0079]
At the time of document reversal, the CPU moves the first mirror unit 208 under the reference white plate 5102, reads one line of shading correction data, and stores the shading correction coefficient obtained by calculation in the coefficient memory in the shading correction circuit 4002. After setting to 4006 (step S10), the first mirror unit 208 is moved below the original glass 14 (step S11).
[0080]
Next, the original 204 is conveyed onto the original reading glass 14 and the original image is subjected to the flow reading operation. The original 204 is separated from the conveying roller 1 by the large lead roller 12 while being separated from the discharge roller. It is conveyed to 11 and below the paper discharge roller 10 (FIG. 3 (i)). Then, the document 204 is discharged onto the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 (FIG. 3 (j)).
[0081]
At this time, the CPU causes the memory 4009 to read the document image data while correcting the document back image data line by line based on the shading correction coefficient obtained in step S10 (step S12).
[0082]
At this point, the original is placed on the original feed tray 9 and turned over, so that the discharged original is oriented in the same direction as when the original is placed on the original feed tray 9. Then, in order to further reverse the original, the upper and lower discharge rollers 11 and 10 are reversely rotated, so that the original 204 is conveyed to the roller 2 in an inverted state (step S13, FIG. k)). In the roller 2, a loop is formed again to correct the skew of the sheet (FIG. 3 (l)).
[0083]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original lead 13 from separating the document 204 from the large conveying roller 1 (FIG. 3). (M)). Then, the original 204 is conveyed onto the flow-reading original reading glass 14, and is conveyed to the upper discharge roller 11 and the lower discharge roller 10 while preventing separation from the conveying roller 1 by the large lead roller 12 (FIG. 3). (N)), the paper is discharged onto the paper discharge tray 15 by the upper paper discharge roller 11 and the lower paper discharge roller 10 (FIG. 3 (o)).
[0084]
When returning the original from the back to the front, the CPU determines whether or not the original placed on the automatic document feeder 200 remains (step S14). The first mirror unit 208 is moved below the reference white plate 5102, one line of shading correction data is read, and the shading correction coefficient obtained by calculation is set in the coefficient memory 4006 in the shading correction circuit 4002 (step S15). Thereafter, the first mirror unit 208 is moved below the original reading glass 14 (step S16), and the next original is read.
[0085]
Thereafter, the processing from step S8 to step S16 is repeated until there is no document, and when there is no document, the image data is read from the memory 4009, and a copy image is formed by the printer unit 202 (step S17). finish.
[0086]
Note that, in the present embodiment, a method has been described in which all document image data is stored in the memory 4009 and then printed out. However, a method in which document image data is printed out while being read into the memory 4009 may be employed.
[0087]
Further, in the present embodiment, when the original is a one-sided original, the shading correction coefficient is updated only before reading the first original. It is also possible to update the shading correction coefficient for each sheet.
[0088]
(Second embodiment)
In the first embodiment, when a single-sided original is to be scanned, a total shading correction coefficient obtained by calculating based on image data obtained by reading the reference white plate 5102 before reading the first original is used. The shading correction of the original was performed, but the shading correction coefficient is corrected in real time according to the data obtained by reading the light amount reference white plate 141 (see FIG. 4) attached to the end of the flow reading original reading glass 14. A well-known shading correction method at the time of flow reading may be used. For example, when the data obtained by reading the light amount reference white plate 141 between the sheets during continuous document conveyance decreases by 2%, the correction coefficient is changed in real time so that the level of the read image signal of the document increases by 2%. Alternatively, a method of correcting the light amount fluctuation of the xenon tube lamp 205 may be used.
[0089]
FIG. 12 is a flowchart for explaining the operation when the shading correction coefficient is corrected in real time between the sheets of the original in the case where the one-sided original is scanned and read. This embodiment is different from the first embodiment only in the processing when the original is a one-sided original, so only the processing for a one-sided original will be described.
[0090]
In FIG. 12, the operator sets a document on the document feed tray 9 of the automatic document feeder 200, designates whether the document is a double-sided document or a single-sided document from an operation unit (not shown) (step S1), and presses a start key. When a copying operation is started by a not-shown (step S2), a CPU (not shown) moves the first mirror unit 208 below the reference white plate 5102, reads one line of shading correction data, and calculates the data. Is set in the coefficient memory 4006 in the shading correction circuit 4002 (step S3).
[0091]
Next, the first mirror unit 208 is moved below the original glass 14 (step S4).
[0092]
Next, it is determined whether the original is a two-sided original or a one-sided original (step S5). If the original is a one-sided original, the feed roller 8 of the automatic original transport device 200 is lowered onto the original 204 (FIG. a)), the uppermost sheet of the document 204 is picked up, and the document 204 is transported to the lower registration roller 3 and the upper registration roller 4 by rotation of the transport roller 6. At the lower registration roller 3 and the upper registration roller 4, a loop is formed in the sheet, and the skew of the sheet is corrected (FIG. 3B).
[0093]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original roller 13 from separating the document 204 from the large conveying roller 1 (FIG. c)).
[0094]
Next, the original 204 is conveyed onto the original reading glass 14 and the original image is subjected to the flow reading operation. The original 204 is separated from the conveying roller 1 by the large lead roller 12 while being separated from the discharge roller. It is conveyed to 11 and below the paper discharge roller 10 (FIG. 3D). Then, the document 204 is discharged to the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 (FIG. 3E).
[0095]
At this time, the CPU reads the document image data into the memory 4009 while correcting the document image data line by line based on the shading correction coefficient obtained in step 3 (step S6).
[0096]
Next, it is determined whether or not there is a next document to be read in the automatic document feeder 200 (step S7). If there is a next document to be read, the light amount affixed to the end of the flow reading document reading glass 14 is determined. The shading correction coefficient is corrected in real time according to the data obtained by reading the reference white plate 141 (step S21). For example, when the data obtained by reading the light amount reference white plate 141 between the sheets during continuous document conveyance decreases by 2%, the correction coefficient is changed in real time so that the level of the read image signal of the document increases by 2%. , The light amount fluctuation of the xenon tube lamp 205 is corrected.
[0097]
Next, the original image data is read into the memory 4009 while correcting the original image data line by line based on the shading correction coefficient corrected in step S18 (step S6).
[0098]
Thereafter, the flow reading operation of the originals (steps S7, S21, S6) is repeated until there are no more originals, and when there are no more originals, the image data is read from the memory 4009 and the printer unit 202 forms a copy image. Then (step S17), the copy operation ends.
[0099]
In the present embodiment, a method is used in which the operator specifies whether the original is a double-sided original or a single-sided original. However, the present invention is not limited to this, and the image reading device may automatically determine the original.
[0100]
(Third embodiment)
FIG. 13 is a flowchart illustrating a procedure of an operation process executed by the image reading apparatus according to the third embodiment of the present invention.
[0101]
In FIG. 13, an operator sets a document on the document feed tray 9 of the automatic document feeder 200, designates whether the document is a double-sided document or a single-sided document from an operation unit (not shown) (step S1), and presses a start key. When the copying operation is started by a not-shown (step S2), the CPU (not shown) moves the first mirror unit 208 below the reference white plate 5102, turns on the xenon tube lamp 205, and shades one line. The correction data is read, and the shading correction coefficient obtained by the calculation is set in the coefficient memory 4006 in the shading correction circuit 4002 (step S3).
[0102]
Next, the first mirror unit 208 is moved below the original glass 14 (step S4).
[0103]
Next, it is determined whether the original is a two-sided original or a one-sided original (step S5). If the original is a one-sided original, the feed roller 8 of the automatic original transport device 200 is lowered onto the original 204 (FIG. a)), the uppermost sheet of the document 204 is picked up, and the document 204 is transported to the lower registration roller 3 and the upper registration roller 4 by rotation of the transport roller 6. At the lower registration roller 3 and the upper registration roller 4, a loop is formed in the sheet, and the skew of the sheet is corrected (FIG. 3B).
[0104]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original roller 13 from separating the document 204 from the large conveying roller 1 (FIG. c)).
[0105]
Next, the original 204 is conveyed onto the original reading glass 14 and the original image is subjected to the flow reading operation. The original 204 is separated from the conveying roller 1 by the large lead roller 12 while being separated from the discharge roller. It is conveyed to 11 and below the paper discharge roller 10 (FIG. 3D). Then, the document 204 is discharged to the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 (FIG. 3E).
[0106]
At this time, the CPU reads the document image data into the memory 4009 while correcting the document image data line by line based on the shading correction coefficient obtained in step S3 (step S6).
[0107]
Next, the document flow reading operation (steps S7 and S6) is repeated until there are no more documents placed on the automatic document feeder 200, and when there is no more documents, the xenon tube lamp 205 is turned off (step S31). The image data is read from 4009, a copy image is formed by the printer unit 202 (step S17), and the copy operation ends.
[0108]
On the other hand, if the original is a double-sided image, the automatic original feeder 200 performs a flow reading operation and corrects the original surface image data line by line based on the shading correction coefficient obtained in step S3. The data is read into the memory 4009 (step S8).
[0109]
Next, the xenon tube lamp 205 is turned off at the same time as performing the document reversing operation to read the back side of the document (step S9) (step S32). The original 204 once conveyed onto the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 (FIG. 3E) is rotated by rotating the upper discharge roller 11 and the lower discharge roller 10 in reverse. The sheet is conveyed to the roller 2 in an inverted state (FIG. 3F). Here, in the roller 2, a loop is formed again and the skew of the sheet is corrected (FIG. 3G).
[0110]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original lead 13 from separating the document 204 from the large conveying roller 1 (FIG. 3). (H)).
[0111]
Next, when the inverted document 204 arrives immediately before the reading position, the xenon tube lamp 205 is turned on (step S33), and the document 204 is conveyed onto the original reading glass 14 (step S11). The flow reading operation is performed, and subsequently, the document 204 is conveyed to the upper discharge roller 11 and the lower discharge roller 10 while preventing separation from the large conveyance roller 1 by the large lead roller 12 (FIG. 3 (i)). ). Then, the document 204 is discharged onto the discharge tray 15 by the upper discharge roller 11 and the lower discharge roller 10 (FIG. 3 (j)).
[0112]
At this time, the CPU reads the document image data into the memory 4009 while correcting the document back surface image data line by line based on the shading correction coefficient obtained in step S3 (step S12).
[0113]
At this point, the original is placed on the original feed tray 9 and turned over, so that the discharged original is oriented in the same direction as when the original is placed on the original feed tray 9. Next, the xenon tube lamp 205 is turned off at the same time as the document is reversed (step S13) (step S34). The document 204 is conveyed to the roller 2 in an inverted state by rotating the upper discharge roller 11 and the lower discharge roller 10 in reverse (FIG. 3 (k)). In the roller 2, a loop is formed again to correct the skew of the sheet (FIG. 3 (l)).
[0114]
Next, the document 204 is pressed against the large conveying roller 1 by the roller 2 and is conveyed in accordance with the rotation of the large conveying roller 1 to prevent the small original lead 13 from separating the document 204 from the large conveying roller 1 (FIG. 3). (M)). Then, the original 204 is conveyed onto the flow-reading original reading glass 14, and is conveyed to the upper discharge roller 11 and the lower discharge roller 10 while preventing separation from the conveying roller 1 by the large lead roller 12 (FIG. 3). (N)), the paper is discharged onto the paper discharge tray 15 by the upper paper discharge roller 11 and the lower paper discharge roller 10 (FIG. 3 (o)).
[0115]
When returning the original from the back to the front, the CPU determines whether or not the original placed on the automatic document feeder 200 remains (step S14). Is transported to the reading position by the automatic document transport device 200, and the xenon tube lamp 205 is turned on when the document 204 reaches just before the reading position (step S35). Then, the original 204 is conveyed onto the original reading glass 14 (step S16). Thereafter, the processing from step S8 to step S16 is repeated until the original is exhausted. When the original is exhausted, the image data is read from the memory 4009. The reading is performed, a copy image is formed by the printer unit 202 (step S17), and the copy operation ends.
[0116]
In the present embodiment, a method has been described in which all the document image data is printed out after being stored in the memory 4009, but a method in which the document image data is printed out while being read into the memory 4009 may be employed.
[0117]
Further, in the present embodiment, a method is used in which the operator designates whether the original is a double-sided original or a single-sided original. However, the present invention is not limited to this, and the image reading device may automatically determine the original.
[0118]
Further, in the present embodiment, the method of continuously lighting the light source that irradiates the original when reading the one-sided original has been described. In this case, the light source may be turned off, the reading operation of the document may be temporarily stopped, and the reading operation of the document may be restarted when the temperature of the light source becomes lower than a predetermined temperature or after the light source is turned off for a predetermined time.
[0119]
A storage medium storing the program code of software for realizing the functions of the above-described embodiments is supplied to a system or an apparatus, and a computer (or CPU or MPU) of the system or the apparatus is stored in the storage medium. It goes without saying that the object of the present invention is also achieved by reading and executing the program code.
[0120]
In this case, the program code itself read from the storage medium implements the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.
[0121]
As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like is used. be able to. Further, the program code may be supplied from a server computer via a communication network.
[0122]
When the computer executes the readout program code, not only the functions of each of the above-described embodiments are realized, but also an OS or the like running on the computer is actually executed based on the instructions of the program code. It goes without saying that a part or all of the processing is performed, and the functions of the above-described embodiments are realized by the processing.
[0123]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that a CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0124]
Hereinafter, examples of embodiments of the present invention will be listed.
[0125]
(Embodiment 1) Automatic document feeding means for continuously transferring a plurality of documents, reversing the document, and enabling both sides of the document to be readable, illuminating means for illuminating the document, and electrically connecting the document image line by line A photoelectric conversion unit for converting a signal into a signal, and an optical unit for forming an image of the reflected light of the original on the photoelectric conversion unit, and an image reading apparatus for reading the original while transporting the original by the automatic original feeding unit,
Calculation means for calculating a shading correction coefficient based on read data obtained by reading a reference white board by the photoelectric conversion means,
A shading correction unit that corrects non-uniformity of at least one of the illumination unit, the photoelectric conversion unit, and the optical unit for each pixel by a shading correction coefficient calculated by the calculation unit;
In the case where the document is read on both sides, when the document is inverted by the document automatic feeding means, a new shading correction coefficient is calculated by the calculation means, and the shading correction coefficient used by the shading correction means is replaced with the new shading correction coefficient. Update means for updating with various shading correction coefficients
An image reading device comprising:
[0126]
(Embodiment 2) Automatic document feeding means for continuously transferring a plurality of documents, reversing the document and enabling reading of both sides of the document, illuminating means for illuminating the document, and electrically connecting the document image line by line A photoelectric conversion unit for converting a signal into a signal, and an optical unit for forming an image of the reflected light of the original on the photoelectric conversion unit, and an image reading apparatus for reading the original while transporting the original by the automatic original feeding unit,
Calculating means for calculating a shading correction coefficient based on read data obtained by reading the first reference white board by the photoelectric conversion means;
A shading correction unit that corrects non-uniformity of at least one of the illumination unit, the photoelectric conversion unit, and the optical unit for each pixel by a shading correction coefficient calculated by the calculation unit;
A light amount fluctuation correction unit that corrects a fluctuation of at least one of the illumination unit and the optical unit on a line-by-line basis based on image reading data in a predetermined region of the second reference white plate;
Switching means for selectively switching which of the shading correction means and the light quantity fluctuation correction means is to be used when the original is read on both sides and when the original is read on one side.
An image reading device comprising:
[0127]
(Embodiment 3) Automatic document feeding means capable of continuously transferring a plurality of documents, inverting the document, and enabling reading of both sides of the document, and illuminating means for illuminating the document
An image reading apparatus that has an original reading unit that reads an original while transporting the original by the original automatic feeding unit,
Control means for controlling to turn off the illuminating means when the original is inverted by the automatic document feeding means when the original is read on both sides;
An image reading device comprising:
[0128]
According to the third embodiment, when the original conveyed by the automatic original conveyance means is a double-sided original, the light source for irradiating the original is turned off at the timing of inverting the original after reading the one side of the original. Therefore, it is possible to read a plurality of double-sided originals in a short time without deterioration in image quality.
[0129]
(Embodiment 4) Automatic document feeding means for continuously transferring a plurality of documents, reversing the document and enabling reading of both sides of the document, illuminating means for illuminating the document, and electrically connecting the document image line by line. A control method for controlling an image reading device that includes a photoelectric conversion unit that converts a signal into a signal, and an optical unit that forms an image of reflected light of the original on the photoelectric conversion unit, and reads the original while conveying the original by the automatic original feeding unit,
A calculating step of calculating a shading correction coefficient based on read data obtained by reading a reference white board by the photoelectric conversion unit,
A shading correction step of correcting, for each pixel, non-uniformity of at least one of the illumination unit, the photoelectric conversion unit, and the optical unit, by a shading correction coefficient calculated by the calculation step;
When the document is read on both sides, when the document is inverted by the document automatic feeding means, a new shading correction coefficient is calculated in the calculation step, and the shading correction coefficient used in the shading correction step is replaced with the new shading correction coefficient. Update step with the appropriate shading correction coefficient
A method for controlling an image reading apparatus, comprising:
[0130]
(Embodiment 5) Automatic document feeding means for continuously transferring a plurality of documents, inverting the document, and enabling both sides of the document to be readable, illuminating means for illuminating the document, and electrically connecting the document image line by line. A control method for controlling an image reading device that includes a photoelectric conversion unit that converts a signal into a signal, and an optical unit that forms an image of reflected light of the original on the photoelectric conversion unit, and reads the original while conveying the original by the automatic original feeding unit,
A calculating step of calculating a shading correction coefficient based on read data obtained by reading the first reference white board by the photoelectric conversion means;
A shading correction step of correcting, for each pixel, non-uniformity of at least one of the illumination unit, the photoelectric conversion unit, and the optical unit, by a shading correction coefficient calculated by the calculation step;
A light amount fluctuation correction step of correcting a fluctuation of at least one of the illumination unit and the optical unit on a line-by-line basis based on image reading data in a predetermined region of the second reference white plate;
A switching step for selectively switching between the shading correction step and the light amount fluctuation correction step depending on whether the original is a two-sided reading or a one-sided reading.
A method for controlling an image reading apparatus, comprising:
[0131]
(Embodiment 6) Automatic document feeding means for continuously transferring a plurality of documents, reversing the document, and enabling reading of both sides of the document, and illuminating means for illuminating the document
A control method for controlling an image reading apparatus that reads an original while transporting the original by the automatic document feeder,
When the document is read on both sides, the illumination unit is turned off when the document is inverted by the document automatic feeding unit.
A method for controlling an image reading apparatus, comprising:
[0132]
(Embodiment 7) Automatic document feeding means for continuously transferring a plurality of documents, reversing the document and enabling reading of both sides of the document, lighting means for illuminating the document, and electrically connecting the document image line by line. A control method for controlling an image reading apparatus comprising: a photoelectric conversion unit for converting a signal into a signal; and an optical unit for forming an image of reflected light of the original on the photoelectric conversion unit, and reading the original while conveying the original by the automatic original feeding unit. A program for
The control method includes:
A calculating step of calculating a shading correction coefficient based on read data obtained by reading a reference white board by the photoelectric conversion unit,
A shading correction step of correcting, for each pixel, non-uniformity of at least one of the illumination unit, the photoelectric conversion unit, and the optical unit, by a shading correction coefficient calculated by the calculation step;
When the document is read on both sides, when the document is inverted by the document automatic feeding means, a new shading correction coefficient is calculated in the calculation step, and the shading correction coefficient used in the shading correction step is replaced with the new shading correction coefficient. Update step with the appropriate shading correction coefficient
Having
A program characterized by the following.
[0133]
(Embodiment 8) Automatic document feeding means for continuously transferring a plurality of documents, reversing the document and enabling reading of both sides of the document, illuminating means for illuminating the document, and electrically connecting the document image line by line. A control method for controlling an image reading apparatus comprising: a photoelectric conversion unit for converting a signal into a signal; and an optical unit for forming an image of reflected light of the original on the photoelectric conversion unit, and reading the original while conveying the original by the automatic original feeding unit. A program for
The control method includes:
A calculating step of calculating a shading correction coefficient based on read data obtained by reading the first reference white board by the photoelectric conversion means;
A shading correction step of correcting, for each pixel, non-uniformity of at least one of the illumination unit, the photoelectric conversion unit, and the optical unit, by a shading correction coefficient calculated by the calculation step;
A light amount fluctuation correction step of correcting a fluctuation of at least one of the illumination unit and the optical unit on a line-by-line basis based on image reading data in a predetermined region of the second reference white plate;
A switching step for selectively switching between the shading correction step and the light amount fluctuation correction step depending on whether the original is a two-sided reading or a one-sided reading.
Having
A program characterized by the following.
[0134]
(Embodiment 9) Automatic document feeding means for continuously transferring a plurality of documents, reversing the document, and enabling reading of both sides of the document, and illuminating means for illuminating the document
A program for realizing a control method for controlling an image reading apparatus that reads a document while transporting the document by the automatic document feeder,
The control method includes:
When the document is read on both sides, the illumination unit is turned off when the document is inverted by the document automatic feeding unit.
A program characterized by the following.
[0135]
【The invention's effect】
As described above, according to the present invention, when a document being conveyed by the automatic document conveyance means is a two-sided document, it is possible to read a plurality of two-sided documents in a short time without deterioration in image quality.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a configuration of the automatic document feeder of FIG.
FIG. 3 is a view for explaining how a document is sent by the automatic document feeder of FIG. 2;
FIG. 4 is a bottom view of the flow-reading glass used in the image reading apparatus according to the embodiment.
FIG. 5 is a diagram showing a configuration of a CCD sensor used in the image reading device of the present embodiment.
FIG. 6 is an enlarged view of a light receiving element of the CCD sensor of FIG.
FIG. 7 is a block diagram illustrating a configuration of a signal processing unit used in the image reading device according to the present embodiment.
FIG. 8 is a block diagram illustrating a configuration of an analog signal processing unit used in the image reading device according to the present embodiment.
FIG. 9 is a diagram illustrating an example of a PG image.
FIG. 10 is a diagram for explaining one method of gradation correction.
FIG. 11 is a flowchart illustrating a procedure of an operation process performed by the image reading apparatus of FIG. 1;
FIG. 12 is a flowchart illustrating a procedure of an operation process executed by the image reading apparatus according to the second embodiment of the present invention.
FIG. 13 is a flowchart illustrating a procedure of an operation process executed by the image reading apparatus according to the third embodiment of the present invention.
[Explanation of symbols]
1 Large transport roller
2 rollers
3 Under the registration roller
4 On the registration roller
6 Transport rollers
8 Paper feed roller
9 Document feed tray
10 Under the discharge roller
11 On the discharge roller
12 Lead Roller Large
13 Lead roller small
14 Original reading glass
200 Automatic Document Feeder
201 Image Scanner Unit
202 Printer section
203 Platen glass
205 Xenon tube lamp
206, 207 Reflecting mirror
2071 Second mirror unit
208 First mirror unit
209 lens
210 3-line sensor
211 signal processing unit
212 Laser Driver
213 Semiconductor laser
214 polygon mirror
215 f-θ lens
216 mirror
217 Photosensitive drum
218 Rotary developer
223 Transfer drum
224,225 paper cassette
226 Fixing unit
5102 Standard white board

Claims (1)

Automatic document feeding means for continuously transferring a plurality of documents, inverting the document, and enabling both sides of the document to be readable, illuminating means for illuminating the document, and photoelectric conversion for converting the document image into electric signals line by line. An image reading apparatus, comprising: a conversion unit, and an optical unit that forms an image of reflected light of the document on the photoelectric conversion unit, and reads the document while conveying the document by the document automatic feeding unit.
Calculation means for calculating a shading correction coefficient based on read data obtained by reading a reference white board by the photoelectric conversion means,
A shading correction unit that corrects non-uniformity of at least one of the illumination unit, the photoelectric conversion unit, and the optical unit for each pixel by a shading correction coefficient calculated by the calculation unit;
When the document is read on both sides, when the document is inverted by the document automatic feeding means, a new shading correction coefficient is calculated by the calculation means, and the shading correction coefficient used by the shading correction means is replaced with the new shading correction coefficient. Updating means for updating with an appropriate shading correction coefficient.

Images