JP2002237932A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that can obtain a proper correction coefficient, even if reading mode of the image reader or the configuration of the image reader is revised, so as to attain effective white level fluctuation correction and maintain satisfactory quality of the read images over a long period. SOLUTION: In the image reader provided with a reference member, a reading means that reads the reference member and an original to provide an output of image data of them, and a correction means that respectively obtains 1st reference data by reading the reference member in a 1st timing and 2nd reference data by reading the reference member in a 2nd timing so as to correct data of the original on the basis of the 1st and 2nd reference data, even if the position of the reference member read in the 2nd timing is changed, the 1st reference data and the 2nd reference data will be data which are obtained by reading the same position of the reference member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading an optical image of a document, storing the read image in a storage means, and outputting the read image to a subsequent stage at a predetermined timing.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus applied to an image forming apparatus such as a copying machine is a CCD (Charge Coupled Device).
e) scans the photoelectric conversion element of (1) to capture an optical image of the original, and converts the optical image into image data of electrical signals. In order to accurately read the optical image of this document, C
Correction of variation in photoelectric conversion efficiency (sensitivity) between pixels of the CD (shading correction) and correction of variation in received light amount due to variation in light amount of a light source (white variation correction)
There is a need to.

In this white variation correction, the reflected light of a white reference plate provided outside the document reading area is read in advance before reading the document, and the data is held as reference data RD.
Immediately before reading the original, the reflected light of the white reference plate is read again, the data is used as sample data D, a correction coefficient is calculated from these data (RD and D), and the image data obtained in the subsequent reading of the original is calculated. The correction is performed in real time by the correction coefficient, and the light amount fluctuation is canceled out.

[0004]

FIG. 13 schematically illustrates such conventional white fluctuation correction. In order to appropriately perform such white variation correction, reference data RD obtained in advance and data D obtained immediately before image reading are used.
It is important that these data are obtained by reading the same position on the same reference plate. That is, in the same figure, when the reference data RD is obtained by reading the position A of a certain reference plate, the data D (1) to D (n) are obtained by reading the position A immediately before reading each image. This is very important. However, for some reason, data D (i) may be obtained by reading a position different from the position A and the position B of the white reference plate immediately before reading the image.

[0005] Such cases include changing the reading mode of the image reading apparatus (for example, reading magnification, black and white or color, drift reading or fixed reading, etc.), and changing the configuration of the image reading apparatus (for example, When an automatic document feeder is installed / removed, etc.).

[0006] Then, since the reading position of the reference data RD is different from the reading position of each data, an appropriate correction coefficient cannot be obtained, and as a result, the white fluctuation correction cannot be performed effectively. Exists.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such technical problems, and its object is to change the reading mode of the image reading apparatus and the configuration of the image reading apparatus. An object of the present invention is to obtain an appropriate correction coefficient to perform effective white variation correction, and to maintain good read image quality for a long period of time.

[0008]

According to the present invention, there is provided a reference member, reading means for reading a reference member and a document, and outputting image data of the reference member, reading the reference member at a first timing, and reading first reference data. A reference member is read at a second timing, second reference data is respectively obtained, and correction means for correcting document data based on the first and second reference data is read at a second timing. Even if the position of the reference member is changed, the first reference data and the second reference data are data obtained by reading the same position of the reference member.

As a more specific mode of such an image reading apparatus, when the position of the reference member read at the second timing is changed, the reference member read at the first timing is changed in accordance with the change. If the position of the member is changed in advance, and there are a plurality of positions of the reference member that can be read at the second timing, the reference member is read at the plurality of positions at the first timing, and the plurality of first reference data is read. In addition, there is a method of correcting the original data based on the first reference data corresponding to the position of the reference member that is actually read at the second timing from among the plurality of first reference data.

Further, when the position of the reference member to be read at the second timing is changed or a plurality of reference members are present, when the reading magnification is changed, whether or not an optional device (for example, an automatic document feeder) is attached, An automatic document feeder capable of reading and fixed reading of a document is provided.

As the reference member, white, gray, metal or the like can be appropriately selected in its color, and metal or various resins can be appropriately selected in its material. And those separated into two or more. “Same position” when the reference member is separated into two or more means “the same position of the same reference member”. Various image correction methods such as white fluctuation correction and shading correction can be applied as a correction method of the correction unit.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on Embodiments 1 to 3 with reference to the drawings as appropriate.

Embodiment 1 FIG. 1 is a schematic sectional view of an image reading apparatus according to the present embodiment. This image reading apparatus is used as a scanner of a copier, and has a casing 10 and a full rate moving within the casing 10 in a scanning direction (sub-scanning direction: indicated by a thick arrow in the drawing) by a full stroke. A carriage 11, a half-rate carriage 12, which also moves half a stroke in the scanning direction, and a platen glass 1 on which the document D is placed.
3 and a platen cover 14 for holding the placed document.

The full-rate carriage 11 contains a lamp La as a light source and a mirror M1, and the half-rate carriage 12 contains mirrors M2 and M3. Further, an imaging lens L is arranged on the optical axis constituted by the mirrors M1, M2 and M3, and a CCD (reading means) 1 is arranged at an imaging position of the imaging lens L. A reading control unit 2 formed on a substrate is arranged below the housing 10 and is electrically connected to the CCD 1 via a harness. A white reference plate (reference member) WR is disposed adjacent to an end of the platen glass 13. The white reference plate WR is used when capturing shading correction data and white fluctuation correction data.

FIG. 2 illustrates a control system of the reading control section 2 with reference to a block diagram. This reading control unit 2
The control unit 20 includes an image processing unit 2A that operates based on an instruction from the control unit 20, a carriage drive control unit 2B, and a lamp lighting control unit 2C. The control unit 20 detects a user interface UI and various sensors S
NR, signals and instructions from the main control unit MC of the copying machine body. The control target of the image processing unit 2A is an image signal read by the CDD 1, and the carriage drive control unit 2B
Is the movement and stop of the full rate carriage 11 and the half rate carriage 12, and the control object of the lamp lighting control unit 2C is the turning on and off of the lamp La.

The image reading of the image reading apparatus will be briefly described. First, a document is placed on a platen glass 13 and a platen cover 14 is closed. Thereafter, light is emitted from the lamp La toward the document together with the reading instruction, and, for example, the full-rate carriage 11 moves all the strokes in the scanning direction and the half-rate carriage 12
Moves half a stroke along the scanning direction. By these movements, the reflected light from the original is changed to mirrors M1, M2
The light is reflected by M3 and is taken into the CCD 1 via the imaging lens L. The CCD 1 converts the optical image of the document into an electric signal in line units in synchronization with the scanning, and sequentially sends the electric signal to the image processing unit 2A.

FIG. 3 is a block diagram for explaining the CDD 1 and the former stage 2A (1) of the image processor 2A. Hereinafter, a description will be given from the upstream side to the downstream side according to the flow of image data.

The CCD 1 includes, for example, red (R), green (G),
It has a configuration in which three line sensors that respectively capture optical images corresponding to blue (B) are arranged in parallel at a predetermined interval.
Channels Ch1 and Ch2 from the red () line sensor
Output signals of channels Ch3 and Ch4 from the green (G) line sensor, and output signals of channels Ch5 and Ch6 from the blue (B) line sensor. LSI 21r, 21
g, 21b. Note that C applied in the present embodiment
It is assumed that CD1 includes three line sensors each including 5000 pixels.

Each analog LSI 21r, 21g, 21b
Obtains output signals from each line sensor of the CCD 1,
AGC (Auto Gain Control) processing and AOC (Auto Off
setControl) process. Each analog LSI 21r,
The output signals of 21g and 21b pass through an A / D (analog / digital conversion) circuit and are converted into digital signals as image processing ICs.
It is passed to 30.

The image processing IC 30 includes R (red), G
Light amount distribution correction circuit 31 that performs shading correction, W-ref correction (correction of the white level of the white reference plate), and white variation correction corresponding to each of the (green) and B (blue) line sensors.
r, 31g, 31b, light amount distribution correction circuits 31r, 31
g, 31b, RAM, CC as storage means for storing shading correction data and white fluctuation correction data.
D1 image capture timing and light intensity distribution compensation circuit 3
A timing generator 32 for generating a signal for setting a timing for reading data from each RAM in 1r-b and the like, and GAP correction circuits 33r and 33g are configured.

FIG. 4 shows the light amount distribution correction circuits 31r and 31.
g and 31b are shown in more detail. That is, the light amount distribution correction circuit 31 performs a predetermined operation on an input signal input for each pixel, so that a multiplier, a divider,
It is composed of a RAM which is a memory. The light amount distribution correction circuit 31 corrects unevenness in sensitivity among the pixels of the line sensor and fluctuations in the light amount of the lamp La with the lapse of time by using these arithmetic functions. On the other hand, the light amount distribution correction circuit 31 is based on a signal obtained by reading the white reference plate WR in advance. The shading correction data is fetched for each pixel and stored in the RAM, and the calculation is performed using the shading correction data stored in the RAM as a variable when calculating the input signal, thereby correcting sensitivity unevenness between the pixels. Generate image data. On the other hand, based on the white variation correction reference data RD of the white reference plate WR read when the power of the image reading apparatus is turned on and the white variation correction sample data SD of the white reference plate WR read immediately before image reading, a correction coefficient is calculated. (SD / RD) is calculated and multiplied by the correction coefficient stored in the RAM when calculating the input signal, thereby generating image data in which the light quantity fluctuation of the lamp La with time is corrected.

FIG. 5 is a flowchart showing a basic operation of the image reading apparatus. FIG. 6 is a flowchart for explaining the operation of S1 of FIG. 5 in more detail. FIG. 7 is an operation of S112 of FIG. FIG. 8 is a flowchart illustrating the operation of S2 in FIG. 5 in more detail. Hereinafter, the operation of the image reading apparatus will be described in detail with reference to the flowcharts shown in FIGS. These operations are all realized by the functions of the reading control unit 2 described with reference to FIG.

The basic operation of this image reading apparatus is shown in FIG.
As shown in the flowchart of step (1), an image reading preparation step (S1) and an image reading execution step (S2)
Until the image reading is completed (S
3), the step of executing image reading is repeated.

Step of preparing for reading the image (S1)
In, shading correction data and white fluctuation correction data are collected. For details, as shown in the flowchart of FIG. 6, first, when the power of the scanner is turned on, the carriages 11 and 12 are initialized (step S101), and the full rate carriage 11 is moved to the shading position X (step S102). ). The shading position X is a position corresponding to a substantially center position of the white reference plate WR. Next, the lamp La (see FIG. 1) is turned on, and waits for 2 seconds (step S103), and then performs AGC processing (step S104). Then
The lamp La is extinguished, a standby of 50 milliseconds is performed (step S105), and an AOC process is subsequently performed (step S1).
06).

Next, the lamp La is turned on, a wait of 100 milliseconds is performed (step S107), and distribution data in the main scanning direction of the CCD line sensor is collected as the first shading correction data (step S107). S1
08). Note that the collected distribution data is written to the RAM.

After the distribution data has been collected, the full rate carriage 11 is moved to the shading position Y.
The shading position Y is a position +2 mm from the shading position X. Full rate carriage 11
Is moved to the shading position Y, distribution data in the main scanning direction of the line sensor is collected as the second shading correction data (step S in FIG. 4).
110). Thereafter, the two pieces of shading correction data collected at the shading positions X and Y are compared and calculated for each pixel, and the larger value is written to the RAM as shading correction data for calculation (step S111).

Here, a procedure for comparing the shading correction data at the positions X and Y will be described. First, the average value of the shading data of a plurality of lines at the position X is compared with the shading data of the plurality of lines at the position Y, and the larger one is defined as the shading data (step S1101). After that, comparison is performed for each pixel, and when the condition is satisfied, the shading correction data is replaced. Then, the shading correction data is transferred from the CPU to the RAM (step S1103: see FIG. 4). After collecting the shading correction data, white fluctuation correction reference data is collected (step S112 in FIG. 6).

The flow of collecting the white fluctuation correction reference data will be described with reference to the flowchart of FIG. First, the full-rate carriage 11 is moved to the white fluctuation correction data collection position A (step S1121). The sampling position A is a position corresponding to a substantially center position of the white reference plate WR, and is the same as the shading position X in the present embodiment. The sampling position A is a position where the white fluctuation correction sample data SD is sampled when an image is read at an image reading magnification of less than 100%. Next, the white variation correction reference data RD (A) is collected and transferred to the memory (step S112).
2). When the white variation correction reference data RD (A) is collected, a plurality of pixels near the optical axis of the line sensor are captured.

Next, the full-rate carriage 11 is moved to the white variation correction reference data collection position B (step S1).
122). The white fluctuation correction data collection position B is a position +5 mm from the position A. The sampling position B is a position where the white variation correction sample data SD is sampled when an image is read at an image reading magnification of 100% or more. After moving the full-rate carriage 11 to the white variation correction data collection position B, the white variation correction reference data RD (B) is collected and transferred to the memory as in step S202 (step S1123).

When all such reading preparations are completed, the image reading apparatus enters a standby state, and waits for an image reading instruction.

Next, the reading execution operation (step S2 in FIG. 5) will be described with reference to the flowchart in FIG. First, the lamp La (see FIG. 1) is turned on (step S201), and the full-rate carriage 11 (see FIG. 1) is stopped at the position A or the position B according to the instructed reading magnification (step S202). That is, the reading magnification is 1
When the reading magnification is less than 100%, the scanning is stopped at the position A, and when the reading magnification is 100 or more, the scanning is stopped at the position B.

After stopping the full-rate carriage 11 at the position A or the position B, the white fluctuation correction sample data S
D is collected (step S203). As with the white variation correction reference data RD, the white variation correction sample data SD is captured for a plurality of pixels near the optical axis of the line sensor.

Next, dark start detection and fail processing are performed (step S204). The dark start detection is to detect that the rising of the lamp is delayed after the scanner has been left for a long time. If this is detected, the standby time due to the rising of the lamp is set longer.

Then, the collected white fluctuation correction sample data SD and the previously collected white fluctuation correction reference data RD
Based on (A) and RD (B), white fluctuation correction coefficient calculation and white fluctuation correction coefficient setting are performed (step S205: see FIG. 4). Here, when the reading magnification of a certain image reading (i) is 100% or more, the white fluctuation correction sample data SD collected immediately before the image reading (i).
(I) and the white variation correction reference data RD previously collected
(B), the white variation correction coefficient P (i) becomes
(I) = (RD (B) / SD (i)),
This is set in the light quantity distribution correction circuit 31 (see FIG. 4). On the other hand, the reading magnification of a certain image reading (j) is 100%.
If the difference is less than the above, based on the white fluctuation correction sample data SD (j) collected immediately before the image reading (j) and the white fluctuation correction reference data RD (A) collected in advance,
When the white variation correction coefficient P (j) is P (j) = (SD (j) /
RD (A)) and is set in the light amount distribution correction circuit 31 (see FIG. 4).

Thereafter, the original D is read.
At this time, based on the shading correction data and the white fluctuation correction coefficient P set in the light amount distribution correction circuit 31, the input data ID is subjected to light amount distribution correction at the same time as reading, and becomes output data ID '(step S20).
6). The reading is performed in this manner.

FIG. 9 schematically shows the essential points of the operation of the image reading apparatus according to this embodiment. The arrow S in the figure indicates the scanning direction, and the arrow t indicates the time axis.
Here, in the reading preparation stage (see step S1 in FIG. 5), the white variation correction reference data RD (A) and the white variation correction reference data RD ( B). On the other hand, in the reading execution stage (see step S2 in FIG. 5), the sampling position of the white variation correction sample data SD differs depending on whether the reading magnification is less than 100% or more than 100%. When the reading magnification is less than 100%, the sampling position of the white variation correction sample data SD is the sampling position A, and when the reading magnification is 100% or more, the sampling position of the white variation correction sample data SD is the sampling position B. .

Even if the reading position of the white fluctuation correction sample data SD is A or B due to the difference in the reading magnification, the white fluctuation correction reference data RD collected at the same position as the sample data SD is used. The white variation correction coefficient P is calculated. As a result, even if the reading magnification is changed, it is possible to obtain an appropriate correction coefficient and perform effective white fluctuation correction, and maintain a good read image quality for a long period of time.

Embodiment 2 FIG. 10 is a schematic sectional view of an image reading apparatus according to this embodiment. This image reading apparatus is used as a scanner of a copier, and has a casing 10 and a full rate moving within the casing 10 in a scanning direction (sub-scanning direction: indicated by a thick arrow in the drawing) by a full stroke. The image reading apparatus according to the first embodiment is similar to the image reading apparatus according to the first embodiment in that a carriage 11, a half-rate carriage 12 that also moves half a stroke in the scanning direction, and a platen glass 13 on which a document D is placed are provided. Hereinafter, differences from the image reading apparatus according to the first embodiment will be mainly described.

The image reading apparatus according to the present embodiment selectively includes a platen cover 14 for pressing the placed document D and an automatic document feeder 15 for continuously placing the document D on the platen glass 13. It can be attached. FIG. 10A shows a state in which the platen cover 14 is attached (in place of the automatic document feeder 15).
FIG. 10B shows a state where the automatic document feeder 15 is attached (in place of the platen cover 14). Then, when the platen cover 14 is used, the white reference plate WR1 is attached to the portion shown in FIG. 10A, and when the automatic document feeder 15 is used, the white reference plate WR1 is detached. The plate WR2 is attached to a position that is advanced in the scan reverse direction from the position where the white reference plate WR1 was attached.

The basic operation of this image reading apparatus comprises an image reading preparation step (S1) and an image reading execution step (S2), as in the first embodiment. Until the image reading is completed (step S1). S3), the steps of image reading execution are repeated (see FIG. 5).

The image reading preparation step (step S1 in FIG. 5) is substantially the same as that of the image reading apparatus according to the first embodiment, except that the white variation correction reference data is collected (step S112 in FIG. 6). It is performed as follows. That is, as shown in the flowchart of FIG. 7, the full-rate carriage 11 is moved to the white variation correction data collection position A (step S1121). The sampling position A is a position corresponding to a substantially central position of the white reference plate WR2. The sampling position A is a position where the white variation correction sample data SD is sampled with the automatic document feeder 15 attached. Next, the white variation correction reference data RD (A) is collected and transferred to the memory (step S1122). When the white variation correction reference data RD (A) is collected, a plurality of pixels near the optical axis of the line sensor are captured.

Next, the full-rate carriage 11 is moved to the white variation correction reference data collection position B (step S1).
122). The white variation correction data collection position B is the white reference plate W
This is a position corresponding to the approximate center position of R1. The sampling position B is a position where the white variation correction sample data SD is sampled with the platen cover 14 attached. After moving the full-rate carriage 11 to the white variation correction data collection position B, the white variation correction reference data RD (B) is collected and transferred to the memory as in step S202 (step S1123).

Next, the reading operation (step S2 in FIG. 5) is substantially the same as that of the image reading apparatus according to the first embodiment, but is performed as follows. That is, as shown in the flowchart of FIG. 8, the lamp La (see FIG. 1) is turned on (step S201), and the full-rate carriage 1 is turned on.
1 (see FIG. 1) is stopped at the position A or the position B according to the instructed reading magnification (step S202). That is, the automatic document feeder 15 is stopped at the position A when the platen cover 14 is attached, and stopped at the position B when the platen cover 14 is attached.

After stopping the full rate carriage 11 at the position A or the position B, the white fluctuation correction sample data S
D is collected (step S203). As with the white variation correction reference data RD, the white variation correction sample data SD is captured for a plurality of pixels near the optical axis of the line sensor. Next, dark start detection and fail processing are performed (step S204).

Then, the collected white variation correction sample data SD and the previously collected white variation correction reference data RD
Based on (A) and RD (B), white fluctuation correction coefficient calculation and white fluctuation correction coefficient setting are performed (step S205: see FIG. 4). Here, when a certain image reading (i) is performed with the platen cover 14 attached, the white fluctuation correction sample data SD (i) taken immediately before the image reading (i) is taken in advance. Based on the white fluctuation correction reference data RD (B), the white fluctuation correction coefficient P
(I) is calculated as P (i) = (RD (B) / SD (i)) and set in the light amount distribution correction circuit 31 (FIG. 4).
reference). On the other hand, when a certain image reading (j) is performed with the automatic document feeder 15 attached, the white fluctuation correction sample data SD (j) collected immediately before the image reading (j) is collected in advance. Based on certain white fluctuation correction reference data RD (A), white fluctuation correction coefficient P (j)
Is calculated as P (j) = (RD (A) / SD (j)), and is set in the light amount distribution correction circuit 31 (see FIG. 4).

Thereafter, the original D is read.
At this time, based on the shading correction data and the white fluctuation correction coefficient P set in the light amount distribution correction circuit 31, the input data ID is subjected to light amount distribution correction at the same time as reading, and becomes output data ID '(step S20).
6).

FIG. 11 schematically shows the essential points of the operation of the image reading apparatus according to this embodiment. The arrow S in the figure indicates the scanning direction, and the arrow t indicates the time axis. Here, in the reading preparation stage (see step S1 in FIG. 5), the white variation correction reference data RD (A) and the white variation correction data correspond to the sampling position A of the white reference plate WR2 and the sampling position B of the white reference plate WR1, respectively. Correction reference data RD (B)
Have gained. On the other hand, the reading execution stage (step S5 in FIG. 5)
2), the platen cover 1 is attached to the image reading apparatus.
4 and the automatic document feeder 15 are attached, the sampling position of the white fluctuation correction sample data SD differs depending on whether the automatic document feeder 15 is attached. When the automatic document feeder 15 is attached, the sampling position of the white variation correction sample data SD is the sampling position A, and when the platen cover 14 is attached, the sampling position of the white variation correction sample data SD is the sampling position A. Position B is reached.

Then, the platen cover 1 is attached to the image reading apparatus.
4 or by attaching the automatic document feeder 15, even if the sampling position of the white variation correction sample data SD is B or A, based on the white variation correction reference data RD collected at the same position as the sample data SD. A white fluctuation correction coefficient P is calculated. As a result, even if the configuration of the members attached to the image reading apparatus is changed, it is possible to obtain an appropriate correction coefficient and perform effective white fluctuation correction, and to maintain a good read image quality for a long period of time. it can.

Embodiment 3 FIG. 12 is a schematic diagram of an image reading apparatus according to the present embodiment. This image reading apparatus is used as a scanner of a copier, and has a casing 10 and a full rate moving within the casing 10 in a scanning direction (sub-scanning direction: indicated by a thick arrow in the drawing) by a full stroke. A carriage 11, a half-rate carriage 12, which also moves half a stroke in the scanning direction, and a platen glass 1 on which the document D is placed.
3 is the same as the image reading apparatuses according to the first and second embodiments. Hereinafter, differences from the image reading apparatuses according to the first and second embodiments will be mainly described.

The image reading apparatus according to the present embodiment is provided with an automatic document feeder 15 for continuously placing the document D on the platen glass 13. Here, FIG. 10A is a schematic sectional view of the image reading apparatus, and FIG. 10B is a schematic top view thereof. The image reading device and the automatic document feeder 15 are provided on the platen glass 1
A so-called platen scan mode in which the original D is temporarily placed on the original 3 and the carriages 11 and 12 move to read the original image while the original D is stationary;
2 is stationary at a predetermined reading position, and has a so-called CVT mode for reading a document image when the document D is conveyed at the reading position.

As the white reference plate, a white reference plate WR2 and a white reference plate WR3 are attached at a position further advanced in the scanning direction than the white reference plate WR2 and further advanced in the scanning orthogonal direction as in the second embodiment. It has gained.

As in the first embodiment, the basic operation of this image reading apparatus comprises an image reading preparation step (S1) and an image reading execution step (S2). Until the image reading is completed (step S1). S3), the steps of image reading execution are repeated (see FIG. 5).

The image reading preparation step (step S1 in FIG. 5) is substantially the same as that of the image reading apparatus according to the first embodiment, except that the white fluctuation correction reference data is collected (step S112 in FIG. 6). It is performed as follows. That is, as shown in the flowchart of FIG. 7, the full-rate carriage 11 is moved to the white variation correction data collection position A (step S1121). The sampling position A is a position corresponding to a substantially central position of the white reference plate WR2. The sampling position A is a position where the white variation correction sample data SD is sampled in the platen scan mode. Next, the white variation correction reference data RD (A) is collected and transferred to the memory (step S1122). White fluctuation correction reference data R
When D (A) is collected, a plurality of pixels near the optical axis of the line sensor are captured.

Next, the full-rate carriage 11 is moved to the white variation correction reference data collection position B (step S1).
122). The white variation correction data collection position B is the white reference plate W
This is a position corresponding to the approximate center position of R3. The sampling position B is the white variation correction sample data S in the CVT mode.
This is the position where D is sampled. Full rate carriage 11
Is moved to the white variation correction data collection position B, and then, as in step S202, the white variation correction reference data RD (B)
Is collected and transferred to the memory (step S112).
3).

Next, the reading operation (step S2 in FIG. 5) is substantially the same as that of the image reading apparatus according to the first embodiment, but is performed as follows. That is, as shown in the flowchart of FIG. 8, the lamp La (see FIG. 1) is turned on (step S201), and the full-rate carriage 1 is turned on.
1 (see FIG. 1) is stopped at the position A or the position B according to the instructed reading magnification (step S202). That is, in the case of the platen scan mode, the CV
In the case of the T mode, it stops at the position B.

After stopping the full-rate carriage 11 at the position A or the position B, the white fluctuation correction sample data S
D is collected (step S203). As with the white variation correction reference data RD, the white variation correction sample data SD is captured for a plurality of pixels near the optical axis of the line sensor. Next, dark start detection and fail processing are performed (step S204).

Then, the collected white fluctuation correction sample data SD and the previously collected white fluctuation correction reference data RD
Based on (A) and RD (B), white fluctuation correction coefficient calculation and white fluctuation correction coefficient setting are performed (step S205: see FIG. 4). Here, when a certain image reading (i) is performed in the CVT mode, the white fluctuation correction sample data SD (i) collected immediately before the image reading (i) and the white fluctuation correction reference data collected in advance. Based on RD (B), the white variation correction coefficient P (i) becomes P (i) = (SD
(I) / RD (B)) and is set in the light amount distribution correction circuit 31 (see FIG. 4). On the other hand, when a certain image reading (j) is performed in the platen scan mode, the white fluctuation correction sample data SD (j) collected immediately before the image reading (j) and the white fluctuation correction reference data Based on RD (A), the white variation correction coefficient P (j) is P (j) = (SD (j) / RD (A))
And is set in the light quantity distribution correction circuit 31 (see FIG. 4).

Thereafter, the original D is read.
At this time, based on the shading correction data and the white fluctuation correction coefficient P set in the light amount distribution correction circuit 31, the input data ID is subjected to light amount distribution correction at the same time as reading, and becomes output data ID '(step S20).
6).

FIG. 11 schematically shows the essential points of the operation of the image reading apparatus according to this embodiment. The arrow S in the figure indicates the scanning direction, and the arrow t indicates the time axis. Here, in the reading preparation stage (refer to step S1 in FIG. 5), the white variation correction reference data RD (A) and the white variation Correction reference data RD (B)
Have gained. On the other hand, the reading execution stage (step S5 in FIG. 5)
2), the sampling position of the white variation correction sample data SD differs depending on whether the image reading is performed in the platen scan mode or the CVT mode. In the case of platen scan mode, white fluctuation correction sample data SD
Is the sampling position A, and the sampling position of the white variation correction sample data SD is the sampling position B in the CVT mode.

When the image reading is performed in the platen scan mode or the CVT mode, the white fluctuation correction sample data SD is collected at the same position as the sample data SD even if the sampling position becomes A or B. A white variation correction coefficient P is calculated based on the correction reference data RD. As a result, even if the image reading mode is changed, an appropriate correction coefficient can be obtained to perform effective white fluctuation correction, and good image quality of the read image can be maintained for a long period of time.

[0061]

As described above in detail, according to the present invention, even if the reading mode of the image reading apparatus or the configuration of the image reading apparatus is changed, an appropriate correction coefficient can be obtained and effective white fluctuation correction can be performed. And good image quality of the read image can be maintained over a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image reading apparatus according to a first embodiment.

FIG. 2 is a block diagram illustrating a control system of the image reading apparatus according to the first embodiment.

FIG. 3 illustrates a part of an image processing unit of the image reading apparatus according to the first embodiment.

FIG. 4 illustrates a light amount distribution correction circuit.

FIG. 5 is a flowchart illustrating a basic operation of the image reading apparatus according to the first embodiment.

FIG. 6 is a flowchart illustrating the read preparation step of FIG. 5 in more detail.

FIG. 7 is a flowchart illustrating in more detail a step of collecting white variation correction reference data of FIG. 6;

FIG. 8 is a flowchart illustrating the reading execution stage of FIG. 5 in more detail;

FIG. 9 is a diagram for explaining a main point of the reading operation of the image reading apparatus according to the first embodiment.

FIG. 10 is a schematic diagram of an image reading apparatus according to a second embodiment.

FIG. 11 illustrates a main point of a reading operation of the image reading apparatus according to the second embodiment (third embodiment).

FIG. 12 is a schematic diagram of an image reading apparatus according to a third embodiment.

FIG. 13 illustrates a conventional image reading apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... case, 11 ... full rate carriage, 12 ... half rate carriage, 13 ... platen glass, 14 ... platen cover, 15 ... automatic document feeder, 2 ... reading control part, 20 ... control part, 2A ... image processing part, 2B: carriage drive control unit, 2C: lamp lighting control unit, 31: light amount distribution correction circuit, WR: white reference plate

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) TT06

Claims (6)

[Claims] 1. A reference member, reading means for reading a reference member and a document and outputting image data thereof, reading the reference member at a first timing, reading first reference data at a second timing, and reading a reference member at a second timing In an image reading apparatus including a second reference data, and a correction unit for correcting the original data based on the first and second reference data, the position of the reference member read at the second timing is changed. Further, the first reference data and the second reference data are data obtained by reading the same position of the reference member. 2. The method according to claim 1, wherein when the position of the reference member read at the second timing is changed, the position of the reference member read at the first timing is changed in advance according to the change. The image reading device according to claim 1. 3. When there are a plurality of positions of the reference member that can be read at the second timing, the reference members are read at the plurality of positions at the first timing to obtain a plurality of first reference data and a plurality of first reference data. 2. The image reading apparatus according to claim 1, wherein the document data is corrected based on the first reference data corresponding to the position of the reference member actually read at the second timing from the one reference data. 4. The position of a reference member read at a second timing is changed according to a reading magnification.
The image reading device according to any one of the above. 5. The image reading apparatus according to claim 1, wherein the position of the reference member read at the second timing is changed depending on whether or not the optional device is mounted. 6. An automatic document feeder capable of reading and fixed reading of a document, wherein the position of a reference member read at a second timing is changed depending on whether the document is flowing or fixed. The image reading device according to any one of claims 1 to 5.