JP2004222041A - Image reader and read preparation method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader which performs actual scanning without degradation of a read quality immediately after user's request for execution of scanning. <P>SOLUTION: When shading and AF processing to read a white reference plate are executed, difference values from preceding shading and AF processing are acquired, and a timer value T being the time to next shading and AF processing is set in accordance with the difference values and a reference table. According as difference values are larger, a smaller value is given as the timer value T. When scanning is indicated by the user, actual scanning is immediately executed on the basis of results of the just preceding shading and AF processing. Thus the waiting time for actual scanning after the indication of scanning is reduced so that a document can be read while more reflecting the latest state of a device. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading apparatus that irradiates a document with light and obtains a document image from the reflected light.
[0002]
[Prior art]
The image reading device uses a lamp (light source) to irradiate light to the surface to be read of the document, and causes a light receiving element (photoelectric conversion element) to scan relative to the document, thereby reflecting light from the document. An image is formed on the light receiving element by a mirror, an imaging lens, or the like. Then, the original image is captured as digital data by performing A / D conversion on the electric signal output from the light receiving element.
[0003]
In order to improve the reading quality in such an image reading apparatus, it is necessary to correct variations in the illuminance of the lamp in the main scanning direction, which is the direction in which the light receiving elements are arranged, and changes over time in the amount of lamp light. This correction is generally called shading correction. It is a general mode of the shading correction processing that a white reference plate serving as a reference of white density is read each time a document is read, and an electric signal of a read image output from a light receiving element is corrected based on the read data. .
[0004]
Techniques for improving the accuracy of shading correction, improving throughput, and stabilizing image quality in an image reading apparatus have already been disclosed (for example, see Patent Documents 1 and 2).
[0005]
[Patent Document 1]
JP-A-8-223416
[Patent Document 2]
JP-A-2000-232558
[0006]
[Problems to be solved by the invention]
Many image reading apparatuses have an autofocus mechanism that can automatically adjust the distance between a document to be read and a light receiving element that forms a read image. Also, there are many image reading apparatuses that allow the user to freely change the reading resolution.
[0007]
FIG. 7 is a diagram schematically illustrating a pre-scanning process corresponding to a reading preparation process up to a scan (main scan) in such an image reading apparatus. First, after the scanning conditions such as the reading resolution are specified by the user (step S101), execution of the scan is instructed (step S102). Then, auto focus setting based on the resolution is performed (step S103), and thereafter, shading correction is performed (step S104). The actual scan for reading the actual document is finally performed (step S105). The setting of the auto focus is performed every time the user instructs the reading, and therefore, the pre-scanning step is indispensable. This has been a factor that hinders the improvement of the throughput of the image reading apparatus.
[0008]
Patent Literature 1 discloses a technique for improving the accuracy of shading correction by devising data sampling at the time of shading correction processing. However, a technique for shortening the pre-scan process as described above is disclosed. Not disclosed.
[0009]
Patent Literature 2 discloses a technique for stabilizing the image quality of a read image and improving the accuracy of shading correction by setting a rising time when a lamp is turned on within a predetermined time. The technique for shortening the pre-scanning process as described above is not disclosed.
[0010]
SUMMARY An advantage of some aspects of the invention is to provide an image reading apparatus that can perform a main scan immediately after a scan execution request is made by a user without deteriorating the reading quality.
[0011]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 uses a light receiving element while adjusting a magnification by a lens to reflect light obtained by irradiating light from the light source onto a reading object while scanning the light source. An image reading apparatus for generating copy image data of the object to be read by receiving light, wherein the color density reference is a reference when correcting the color density value of the copy image data, and the color density reference is A reference reading process of receiving reflected light obtained by irradiating light from the light source with the light receiving element, and a correction process of correcting a color density value of the copy image data based on a result of the reference reading process. Shading processing means for performing, and timer value setting means for setting, as a timer value, a time from when the reference reading processing is performed to when the reference reading processing is performed next time, When the time set as the mer value has elapsed, performing the next of the reference reading process, characterized in that.
[0012]
The invention according to claim 2 is characterized in that the reflected light obtained by irradiating the object to be read with light from the light source while scanning the light source is received by a light receiving element while adjusting the magnification by a lens, so that the reading is performed. An image reading apparatus for generating copy image data of a target object, wherein a color density reference object serving as a reference when correcting a color density value of the copy image data, and irradiating the color density reference object with light from the light source. A shading processing unit for performing a reference reading process of receiving the reflected light obtained by the light receiving element and a correction process of correcting a color density value of the copy image data based on a result of the reference reading process; An auto focus which is executed continuously with the reference reading process and performs an auto focus process for optimizing a condensing state of the reflected light on the light receiving element by adjusting an arrangement position of the lens. Processing means, and a timer value setting means for setting a time until the next execution of the two processes as a timer value after once executing the two processes of the reference reading process and the autofocus process. The method further comprises performing the next reference reading process when the time set as the timer value elapses after the autofocus process ends at a certain time.
[0013]
According to a third aspect of the present invention, there is provided the image reading apparatus according to the second aspect, wherein a new arrangement position of the lens obtained by the most recent autofocus process, and an arrangement position of the lens up to that time. A first temporary timer value determined based on the difference value of the above, the color density value of the new color density reference material obtained by the latest reference reading process, and the color density value of the color density reference material immediately before that. And setting a smaller one of the second temporary timer values determined based on the difference value as the new timer value.
[0014]
According to a fourth aspect of the present invention, in the image reading device according to the third aspect, a correspondence relationship between the first temporary timer value and a difference value between the lens arrangement positions, and the second temporary timer value The correspondence relationship between the color density value and the difference value is that at least one of the first and second temporary timer values is set to be smaller as the corresponding difference value is larger. It is characterized.
[0015]
According to a fifth aspect of the present invention, in the image reading device according to the first or second aspect, a predetermined increment value is added to a previous timer value until a predetermined upper limit value is reached. A new value of the timer value is set.
[0016]
Further, the invention according to claim 6 is to receive reflected light obtained by irradiating light from the light source on the reading object while scanning the light source with a light receiving element while adjusting magnification by a lens, A reading preparation method of an image reading apparatus that generates copy image data of the read object, wherein the light source irradiates light to a color density reference object that is a reference when correcting a color density value of the copy image data. A reference reading process in which the reflected light obtained by the light receiving element is received by the light receiving element, and a timer for setting a time from when the reference reading process is performed once to when the reference reading process is performed next time as a timer value. A value setting step, wherein when the time set as the timer value has elapsed, the next reference reading processing step is performed.
[0017]
According to a seventh aspect of the present invention, the reflected light obtained by irradiating the object to be read with light from the light source while scanning the light source is received by a light receiving element while adjusting the magnification by a lens. A reading preparation method of an image reading apparatus that generates copy image data of the read object, wherein the light source irradiates light to a color density reference object that is a reference when correcting a color density value of the copy image data. A reference reading processing step in which the reflected light obtained by the light receiving element is received by the light receiving element; and a reference reading processing step, which is executed in succession to the reference reading processing step. After the two processes of the autofocus process for optimizing the light state and the reference reading process and the autofocus process are performed once, the two processes are performed next time. A timer value setting step of setting the time until the timer reading as a timer value.After the autofocus processing step ends at a certain point in time, when the time set as the timer value elapses, the next reference reading is performed. Performing a processing step.
[0018]
The invention of claim 8 is the reading preparation method of the image reading device according to claim 7, wherein the new arrangement position of the lens obtained by the most recent autofocus processing step and the position of the new lens up to that time are obtained. A first provisional timer value determined based on a difference value between the lens arrangement position, a color density value of the new color density reference object obtained in the latest reference reading process, and the color density reference immediately before The second temporary timer value determined based on the difference value between the color density value of the object and the second temporary timer value is set as a new value of the timer value.
[0019]
According to a ninth aspect of the present invention, there is provided the reading preparation method for the image reading apparatus according to the eighth aspect, wherein the correspondence between the first temporary timer value and the difference value between the lens arrangement positions, and the second The correspondence between the provisional timer value and the difference value between the color density values is set so that at least one of the first and second provisional timer values becomes smaller as the corresponding difference value increases. It is characterized by having.
[0020]
According to a tenth aspect of the present invention, in the reading preparation method of the image reading device according to the sixth or seventh aspect, a predetermined increment value is added to a previous timer value until a predetermined upper limit value is reached. The timer value is added and a new value of the timer value is set.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
<Apparatus configuration>
FIG. 1 is a diagram schematically illustrating a configuration of an image reading apparatus 100 according to an embodiment of the present invention. The image reading apparatus 100 is a so-called flat-bed type scanner, and mainly includes an original placing section 10, an optical scanning section 20, a control section 30, and an input interface (I / F) 36.
[0022]
The document placement unit 10 includes a document table 11 on which a document to be read is placed, a white reference plate 12 that is read when shading correction is performed, and a document that is used when auto focus (AF) is performed. And an AF reference plate 13 to be read.
[0023]
The platen 11 is a transparent and smooth plate made of, for example, glass, and is emitted from a light source 21 described later provided in the optical scanning unit 20 in a state where the document is placed on the reading area 14 above the platen. The original is irradiated with light transmitted through the original.
[0024]
The white reference plate 12 is a white plate that serves as a color density reference object in the shading correction for correcting the deviation of the color density value due to the illuminance of the light source 21 and the later-described variation in the light receiving sensitivity of the CCD element 22 for the read image data. It is. In the present embodiment, the reference reading process for reading the reflected light from the white reference plate is referred to as “performing shading”, and performing the correction process based on the result is referred to as “shading correction”. Is performed. "
[0025]
The AF reference plate 13 serves as a reference when adjusting the focus of a lens 23 described later provided in the optical scanning unit 20. For example, several reference lines L as shown in FIG. 4A are formed on the surface of the AF reference plate 13 on which light is irradiated, and read data of an area RG including the reference lines L is formed. Based on this, the AF process is executed.
[0026]
The optical scanning unit 20 is provided to perform irradiation of light on a document and reading of reflected light from the document while scanning the light. The optical scanning unit 20 includes, for example, a fluorescent lamp such as a xenon lamp, and a light source 21 that irradiates a predetermined position of the document placing unit 10 with light, and a CCD element 22 that is a light receiving element that receives reflected light from the document. A lens 23 for adjusting the magnification of the reflected light, a lens driving mechanism 24 having a pulse motor or the like for adjusting the position of the lens 23, and the entire optical scanning unit 20 in a predetermined direction (for example, FIG. And a scanning drive mechanism 25 for driving in the left-right direction.
[0027]
The control unit 30 includes an A / D converter 31 that converts an electric signal generated according to the amount of reflected light received from the document into luminance information (color density value), and a color density of each pixel acquired from the document. A memory 32 that holds a set of values as document image data and stores various setting data, a CPU 33 that functions as control means for controlling each unit, a lens driving mechanism 24 and a scanning drive And a driver 34 for driving the mechanism 25. The memory 32 includes a ROM, a RAM, a nonvolatile memory, and the like. The memory 32 includes an image memory 32a that holds original image data, and a reference table (referred to when setting pre-scan timing). Various reference data such as LUT 32b are stored in advance.
[0028]
In the control unit 30, the scan processing unit 41, the AF processing unit 42, the shading processing unit 43, and the first temporary timer value determining unit are used as components for performing various processes by the operation of the memory 32 and the CPU 33. 44, a second provisional timer value determining means 45, and a timer value setting means 46 are realized (see FIG. 3).
[0029]
The scan processing unit 41 performs a process related to a main scan for actually reading a document. The scan processing unit 41 operates the optical scanning unit 20 in accordance with various operation settings in the main scan, such as a reading resolution and a reading area, which are provided through the input I / F 36, and acquires document image data DD.
[0030]
The AF processing unit 42 performs a process of setting a focus position of the lens 23. The AF processing unit 42 drives the lens driving mechanism 24 to read the AF reference plate 13 while changing the position of the lens 23, and sets the in-focus position of the lens 23 based on the result.
[0031]
The shading processing means 43 performs a process for shading correction on the read image data DD. The shading processing unit 43 reads the white reference plate 12, obtains a correction coefficient (described later) for shading correction based on the result, and uses the correction coefficient to convert the corrected image from the read image data DD. Generate data DC.
[0032]
Each of the first provisional timer value determination means 44, the second provisional timer value determination means 45, and the timer value setting means 46 is responsible for setting a prescan interval.
[0033]
The input I / F 36 is an interface for the user to input a scan instruction, a predetermined set value, and the like.
[0034]
Note that the image reading apparatus 100 may be configured such that the document placement unit 10, the optical scanning unit 20, the control unit 30, and the input I / F 36 are all integrated into one housing. Then, the document placement unit 10 and the optical scanning unit 20 are incorporated as a main unit in one housing, and the control unit 30 and the input I / F 36 are realized by a personal computer and provided so as to be able to communicate with the main unit. There may be.
[0035]
<Process flow>
The image reading apparatus 100 according to the present embodiment performs a pre-scanning process (shading and AF processing) for reading preparation in a predetermined manner so that a main scan can be immediately executed when a scan instruction is given from a user. It is characteristic in that it can be executed in advance at time intervals and the time interval can be flexibly set based on the result of the pre-scanning step. FIG. 2 is a diagram showing a flow of processing for that. FIG. 3 is a diagram showing the relationship between the above-described components realized by the operation of the memory 32 and the CPU 33 and data generated in the processing shown in FIG.
[0036]
First, the resolution at the time of reading is designated by the user through the input I / F 36 in advance (step S1). For the sake of simplicity, it is assumed that there is no change in the resolution setting hereinafter.
[0037]
When the resolution is set, a pre-scan, which is a stage before the main scan, is performed. First, shading for reading reflected light from the white reference plate 12 is performed by the operation of the shading processing unit 43 (step S2). Now, the true color density value of the white reference plate 12 is V, the output value when the white reference plate is read is the first shading data DS1, the image data at the time of reading is read image data DD, and the corrected image data is corrected. Assuming that the image data is DC,
DC = DD × V / DS1 (Equation 1)
Holds for each pixel. Executing the shading correction is nothing but obtaining corrected image data DC based on the relationship of Expression 1. By executing the shading in step S2, the first shading data DS1 is obtained, and the coefficient V / DS1 on the right side of Expression 1 is obtained. As described later, until the shading is performed again, shading correction using the coefficient V / DS1 as a correction coefficient is performed.
[0038]
Subsequent to the execution of the shading, the AF processing is performed by the operation of the AF processing means 42 (step S3). FIG. 4 is a diagram for explaining the AF processing. In the AF process, the lens driving mechanism 24 is driven to change the lens position, and each of the lens positions is moved from the region RG including the reference line L formed on the AF reference plate 13 shown in FIG. The process of reading the reflected light is performed in a predetermined lens position range. The lens position can be represented by, for example, the number of pulses of a pulse motor provided in the lens driving mechanism 24.
[0039]
The focus position is determined by performing the processing outlined in FIG. 4B at each lens position. The lens position determined as the in-focus position is obtained as the first AF data DA1. That is, (1) when the density profile P1 for the region RG is obtained, (2) first, an averaging process (noise filter process) is performed on the density profile P1 to obtain an averaging profile P2, and (3) the averaging profile P2 is further obtained. , A USM (unsharp masking) profile P3 in the main scanning direction is obtained. (4) The difference between the averaged profile P2 and the USM profile P3 is calculated, and the absolute value is calculated to generate an edge profile P4. While changing the lens position, the edge profile P4 is obtained for each of several points, and the lens position where the sum of absolute values is maximum in the main scanning direction is acquired as the in-focus position, that is, as the first AF data DA1. You. As described later, the lens 23 is arranged at the lens position acquired as the first AF data DA1, and the main scan is executed until the AF process is executed again.
[0040]
After the completion of the AF processing, a main scan for actually reading a document image becomes possible. At this point, the timer 35 is given a predetermined initial value T0 as a timer value T for the time until the next pre-scan is executed (step S4), and the operation is immediately started (step S5). .
[0041]
During the operation of the timer 35, the scan processing unit 41 constantly monitors the presence or absence of a scan instruction from the user via the input I / F 36 until the timer value T reaches 0 (steps S6 and S8). When a document is placed on the document table 11 during the timer operation and a scan instruction is given, a main scan for reading a document image is executed by the operation of the scan processing means 41 (step S7). The scan processing means 41 receives the reflected light of the light emitted from the light source 21 by the CCD element 22 while driving the scanning drive mechanism 25 through the driver 34, and acquires the read image data DD via the A / D converter 31. . When the read image data DD is obtained, shading correction is performed for each pixel based on Equation 1, and corrected image data DC is obtained. The corrected image data DC is used in various image processing devices and the like as output data from the image reading device 100.
[0042]
Regardless of whether the main scan is performed or not, when the time T0 elapses from the start of the operation of the timer 35 and the timer value T reaches 0 (YES in step S8), shading is performed again (step S9), and subsequently, AF processing is performed (step S10). If the timer value T reaches 0 during the main scan, the pre-scan step is performed similarly after the main scan. In each case, the execution content itself is the same as in the case described above. At this time, the first shading data DS1 and the first AF data DA1 acquired last time are rewritten as the second shading data DS2 and the second AF data DA2, respectively. Then, new first shading data DS1 and new first AF data DA1 are obtained by the pre-scan process newly executed in step S9 and step S10. Thereafter, similarly, when the pre-scan is repeatedly performed, the first shading data DS1 and the first AF data DA1 acquired immediately before are rewritten as the second shading data DS2 and the second AF data DA2.
[0043]
When the prescan is performed again in steps S9 and S10, a timer value T for the next operation of the timer 35 is set based on the difference between the previous and current data in each case. Specifically, first, the first provisional timer value determining means 44 determines the first provisional timer value Tx based on the difference between the first AF data DA1 and the second AF data DA2 (step S11). Further, the second provisional timer value determining means 45 determines the second provisional timer value Ty based on the difference between the first shading data DS1 and the second shading data DS2 (step S12). Then, the first provisional timer value Tx and the second provisional timer value Ty are compared by the timer value setting means 46, and the smaller value is set as the timer value T for the next timer operation (step S13). .
[0044]
The determination of the first provisional timer value Tx by the first provisional timer value determination means 44 and the determination of the second provisional timer value Tx by the second provisional timer value determination means 45 are each performed using a reference table for the above-described difference values. 32b. FIG. 5 is a diagram illustrating an example of the reference table 32b. FIG. 5A shows an example of the lookup table LUT1 used to determine the first temporary timer value Tx. The lookup table LUT1 shows the correspondence between the difference value ΔX between the first AF data DA1 and the second AF data DA2 and the first provisional timer value Tx when the lens position is determined as the pulse value of the pulse motor. FIG. 5B shows an example of the lookup table LUT2 used when determining the second provisional timer value Ty. The lookup table LUT2 indicates the correspondence between the difference value ΔY between the first shading data DS1 and the second shading data DS2 and the second temporary timer value Ty when the color density value is represented by 256 gradations from 0 to 255. ing.
[0045]
In each of the lookup tables LUT1 and LUT2, the correspondence between the difference value and the provisional timer value is set such that the larger the difference value ΔX or ΔY, the smaller the first provisional timer value Tx or the second provisional timer value Ty is set. A spell has been made. For example, when the operation of the image reading apparatus 100 is not sufficiently stable, for example, immediately after startup, the first shading data DS1 or the first AF data acquired in shading or AF processing due to a large fluctuation in the light amount of the light source 21 or the like. It is estimated that the change in DA1 is large and the respective difference values are large. In such a case, in order to appropriately reflect those changes in maintaining the reading quality, it is desirable to perform the shading and the AF processing at small time intervals. Therefore, the temporary timer value is set as a small value. Conversely, when the operation is stable, it is estimated that the temporal variation of the first shading data DS1 and the first AF data DA1 is small. In such a case, even if the main scan or the shading correction is performed using the first shading data DS1 or the first AF data DA1 after a relatively long time has elapsed from the acquisition, it is considered that the influence on the quality of the read image is small. The provisional timer value is set as a large value.
[0046]
In step S13, the reason why the value of the first temporary timer value Tx and the value of the second temporary timer value Ty are smaller is set as the timer value T in order to minimize the influence of fluctuation.
[0047]
When the timer value T is set, the process returns to step S5, and the above processing is repeated. That is, when the user instructs a scan, the main scan and the subsequent shading correction are immediately performed based on the first shading data DS1 and the first AF data DA1 obtained as a result of the latest pre-scan process. Further, every time the timer value T determined according to the operation stability of the image reading apparatus 100 reaches 0, the pre-scanning step is performed, and the first shading data DS1 and the first AF data DA1 are updated. In response to the instruction, the original is read more reflecting the latest state of the apparatus. As a result, an image reading apparatus is realized in which the waiting time from when a scan instruction is issued to the main scan is reduced, throughput is improved, and reading quality is not degraded.
[0048]
<Modification>
In the above embodiment, the timer value T is set using the reference table 32b, but the timer value T may be set by a different method. FIG. 6 is a diagram showing an example of this, and shows a flow of processing when the timer value T is set by increasing the timer value T by a constant increment value ΔT.
[0049]
In the flow of the process shown in FIG. 6, the contents from step S21 to step S30 are the same as the contents from step S1 to step S10 in FIG. 2, and a description thereof will be omitted. In step S31, a predetermined increment value ΔT is added to the timer value T set immediately before, and a new timer value T is set. However, if the timer value T is set to an infinitely large value, shading and AF processing are not substantially performed. Therefore, a certain upper limit value T2 is provided, and the timer value T exceeds the upper limit value T2. If not, the timer 35 is operated using the timer value T as it is (NO in step S32), and if the timer value T exceeds the upper limit value T2 (YES in step S32), the timer value T is thereafter increased to the upper limit value. It is fixed to T2 (step S33).
[0050]
Even in this case, the increment value ΔT is determined so that the state of the apparatus can be more reflected immediately after the start, for example, so that if the scan instruction is issued, the state of the apparatus is more reflected as in the above-described embodiment. The main scan can be executed immediately using the set settings.
[0051]
Note that the processing shown in FIG. 2 and the processing shown in FIG. 6 may be selectively used.
[0052]
In the case of the image reading apparatus 100 according to the above-described embodiment, the document is fixed to the document table 11 and the optical scanning unit 20 is driven. However, the optical system such as the light source and the light receiving element is fixed, and the document is fixed. Even in a mode in which scanning is performed by driving a document table on which a document is placed, similarly to the above-described embodiment, the timer value can be set, and the same effect can be obtained. .
[0053]
Further, in the image reading apparatus 100 according to the above-described embodiment, the AF processing unit is not used and the image processing apparatus functions as a single-focus fixed image reading apparatus, or a single-focus fixed image that does not include the AF processing unit from the beginning. In the case of a reading apparatus, steps S3 and S10 in FIG. 2 are omitted, and instead of setting the timer value T in steps S11 to S13, the second provisional timer value Ty is directly used as the timer value T from the shading execution result. Thus, a similar effect can be obtained.
[0054]
【The invention's effect】
As described above, according to the first and sixth aspects of the present invention, when a user issues an instruction to read an object to be read, the object to be read is immediately read based on the result of the latest reference reading process. Can be performed, so that the throughput can be improved.
[0055]
According to the second to fourth and seventh to ninth aspects of the present invention, when a user instructs to read an object to be read, the latest reference reading process and the autofocus process are performed. Since the reading of the object to be read can be immediately performed based on the result, the throughput can be improved.
[0056]
According to the third, fourth, eighth, and ninth aspects of the present invention, the timer value is set based on the difference value. Since the interval at which the focus processing is performed can be determined, even if the reading is executed immediately after the reading instruction, the influence of the state change of the apparatus on the quality of the read image can be suppressed.
[0057]
According to the fourth and ninth aspects of the invention, the reference reading process and the autofocus process are performed at small time intervals when the state of the apparatus is large, and at large time intervals when the state of the apparatus is small. Since the reference reading process and the autofocus process are performed, it is possible to improve the throughput and maintain the quality of the read image.
[0058]
According to the fifth and tenth aspects of the present invention, the reference reading process and the auto-focusing process are executed at short time intervals immediately after the start-up of the image reading apparatus, which is likely to be not sufficiently stable. When a sufficient time has elapsed from the start, the reference reading process and the autofocus process are executed at regular time intervals. Therefore, the reference reading process and the autofocus process are executed at appropriate time intervals according to the state of the apparatus. Can be.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a configuration of an image reading apparatus 100.
FIG. 2 is a diagram showing a flow of processing for setting a timer value.
FIG. 3 is a diagram showing a relationship between each of the above-described components realized by the operation of a memory 32 and a CPU 33, and data generated in the processing shown in FIG. 2;
FIG. 4 is a diagram for explaining an AF process.
FIG. 5 is a diagram showing an example of a reference table 32b.
FIG. 6 is a diagram illustrating a modification of setting of a timer value.
FIG. 7 is a diagram illustrating a pre-scanning process in a conventional image reading apparatus.
[Explanation of symbols]
11 Platen
12 White reference plate
13 Reference plate
100 Image reading device
21 Light source
22 CCD device
23 lenses
24 Lens drive mechanism
25 Scanning drive mechanism
32 memories
P1 concentration profile
P2 Averaging profile
P3 USM profile
P4 edge profile

Claims (10)

Reflected light obtained by irradiating light from the light source on the object to be read while scanning the light source is received by a light receiving element while adjusting the magnification by a lens, so that copy image data of the object to be read is obtained. An image reading device for generating,
A color density reference that serves as a reference when correcting the color density value of the copy image data;
A reference reading process in which the light receiving element receives reflected light obtained by irradiating the color density reference object with light from the light source; and correcting a color density value of the copy image data based on a result of the reference reading process. Shading processing means for performing correction processing to be performed;
After once executing the reference reading process, a timer value setting means for setting a time until the next time the reference reading process is executed as a timer value,
With
When the time set as the timer value has elapsed, perform the next reference reading process,
An image reading apparatus, comprising: Reflected light obtained by irradiating light from the light source on the object to be read while scanning the light source is received by a light receiving element while adjusting the magnification by a lens, so that copy image data of the object to be read is obtained. An image reading device for generating,
A color density reference that serves as a reference when correcting the color density value of the copy image data;
A reference reading process in which the light receiving element receives reflected light obtained by irradiating the color density reference object with light from the light source; and correcting a color density value of the copy image data based on a result of the reference reading process. Shading processing means for performing correction processing to be performed;
An autofocus processing unit that is executed continuously with the reference reading process, and performs an autofocus process that optimizes a focusing state of the reflected light on the light receiving element by adjusting an arrangement position of the lens,
A timer value setting unit configured to set a time until a next execution of the two processes as a timer value after once executing the two processes of the reference reading process and the autofocus process;
With
After the autofocus process is completed at a certain point in time, when the time set as the timer value has elapsed, perform the next reference reading process,
An image reading apparatus, comprising: The image reading device according to claim 2,
A first provisional timer value determined based on a difference value between the new arrangement position of the lens obtained by the most recent autofocus process and the arrangement position of the lens up to that time,
A second temporary timer value determined based on a difference value between a color density value of the new color density reference material obtained by the latest reference reading process and a color density value of the color density reference material immediately before;
An image reading apparatus that sets a smaller one of the timer values as a new value of the timer value. The image reading device according to claim 3,
The correspondence relationship between the first temporary timer value and the difference value between the lens arrangement positions and the correspondence relationship between the second temporary timer value and the difference value between the color density values is determined by the first and second temporary timer values. At least one of the timer values is set to be smaller as the corresponding difference value is larger,
An image reading apparatus, comprising: The image reading device according to claim 1 or 2, wherein:
Until the predetermined upper limit is reached, a new increment of the timer value is set by adding a certain increment to the previous timer value,
An image reading apparatus, comprising: Reflected light obtained by irradiating light from the light source on the object to be read while scanning the light source is received by a light receiving element while adjusting the magnification by a lens, so that copy image data of the object to be read is obtained. A reading preparation method for an image reading device to be generated,
A reference reading processing step of receiving, by the light receiving element, reflected light obtained by irradiating light from the light source to a color density reference object serving as a reference when correcting the color density value of the copy image data,
After once executing the reference reading processing step, a timer value setting step of setting a time until the next execution of the reference reading processing step as a timer value,
With
When the time set as the timer value has elapsed, perform the next reference reading process step,
A reading preparation method for an image reading apparatus. Reflected light obtained by irradiating light from the light source on the object to be read while scanning the light source is received by a light receiving element while adjusting the magnification by a lens, so that copy image data of the object to be read is obtained. A reading preparation method for an image reading device to be generated,
A reference reading processing step of receiving, by the light receiving element, reflected light obtained by irradiating light from the light source to a color density reference object serving as a reference when correcting the color density value of the copy image data,
An auto-focus processing step which is performed continuously to the reference reading processing step, and optimizes a condensing state of the reflected light on the light receiving element by adjusting an arrangement position of the lens;
After once executing the two processes of the reference reading process and the autofocus process, a timer value setting process of setting a time until the next execution of the two processes as a timer value,
With
After the autofocus process at a certain point in time, when the time set as the timer value has elapsed, perform the next reference reading process,
A reading preparation method for an image reading apparatus. It is a reading preparation method of the image reading device of Claim 7, Comprising:
A first provisional timer value determined based on a difference value between the new arrangement position of the lens obtained by the most recent autofocus processing step and the arrangement position of the lens up to that time,
A second temporary timer value determined based on a difference value between the color density value of the new color density reference material obtained by the latest reference reading processing step and the color density value of the color density reference material immediately before; ,
Setting a smaller one of the timer values as a new value of the timer value. It is a reading preparation method of the image reading device of Claim 8, Comprising:
The correspondence relationship between the first temporary timer value and the difference value between the lens arrangement positions and the correspondence relationship between the second temporary timer value and the difference value between the color density values is determined by the first and second temporary timer values. At least one of the timer values is set to be smaller as the corresponding difference value is larger,
A reading preparation method for an image reading apparatus. A reading preparation method for an image reading apparatus according to claim 6, wherein:
Until the predetermined upper limit is reached, a new increment of the timer value is set by adding a certain increment to the previous timer value,
A reading preparation method for an image reading apparatus.

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