JP2000122188A - Image reader, image reading method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader, an image reading method and a storage medium capable of cosiderably reducing the fluctuation of read density and that of a read color. SOLUTION: This reader is provided with an illuminating light source 110 illuminating an original, an image sensor 101 converting reflected light from the original or a reference white board into an electrical signal, a lamp power source 111 varying light quantity radiated from the light source 110 to the appropriate light quantity, variable gain amplifiers 102 to 104 amplifying an output signal from the image sensor 101 to an appropriate signal level, and a CPU 112 changing a light quantity control value for a lamp power source 111 in accordance with the signal level in the case of reading the reference white board and changing a gain control value for the amplifiers 102 and 104.

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, an image reading method, and a storage medium, and more particularly, to reading density at the time of reading an image using an image sensor that converts reflected light from a document into an electric signal. The present invention relates to an image reading apparatus, an image reading method, and a storage medium that are suitable for reducing fluctuations and reading color fluctuations.

[0002]

2. Description of the Related Art Conventionally, there is an image reading apparatus provided with an image sensor for converting reflected light from a document into an electric signal, a reference white plate for shading correction, and the like.

FIG. 11 is a schematic diagram showing a configuration of an image reading system of an image reading apparatus according to a conventional example. The image reading system of the image reading apparatus includes a platen glass 1101 and a dummy glass 110.
3. Reference white plate (hereinafter, white plate) 1104 for shading correction, illumination light source 1105 for document illumination, first mirror 1106, second mirror 1107, third mirror 110
8, a lens 1109, and an image sensor 1110.

In FIG. 11, reflected light from a document 1102 passes through a first mirror 1106, a second mirror 1107, a third mirror 1108, and a lens 1109, and the image sensor 1
An image is formed on the light receiving surface of the
At 0, it is converted to an electrical signal. In this case, the white plate 110
Reference numeral 4 is provided on the upper surface of the dummy glass 1103, and image data read from the white plate 1104 is used as a coefficient of shading correction (correction of color unevenness of a read image) when reading a document.

FIG. 12 is a perspective view showing a configuration example of a scanning mechanism for two-dimensionally reading a document image by moving the first to third mirrors of an image reading apparatus according to a conventional example.
The scanning mechanism of the image reading apparatus includes a document scanner motor 1
201, timing belt 1202, mirror drive shaft 12
03, wires 1204 and 1205, a first mirror base 1206 mounting a first mirror, a second mirror base 1207 mounting a second mirror and a third mirror, and a signal plate 120.
8. A home position sensor 1209 is provided.

Referring to FIG. 4, a document scanner motor 120
The rotation of 1 rotates the mirror drive shaft 1203 via the timing belt 1202. The rotation of the mirror driving shaft 1203 winds the wires 1204 and 1205, and moves the first mirror base 1206 and the second mirror base 1207.
At this time, the movement amount of the second mirror base 1207 is set to be exactly の of the movement amount of the first mirror base 1206. The signal plate 1208 and the home position sensor 1209 are connected to the first mirror base 120.
6 is for detecting that it is at a predetermined position (home position). When the signal plate 1208 crosses the home position sensor 1209, an electric signal is output from the home position sensor 1209.

FIG. 13 is an explanatory diagram showing an example of a sequence in the case where a document image is read using the image reading apparatus shown in FIGS. 11 and 12. That is, FIG. 13 is an example of a sequence in which the following (A) shading sample and (B) scan (image reading) are alternately repeated to perform image reading M times.

(A) Shading sample The white plate 1104 is read, and the read image data is stored in a memory for use as a shading correction coefficient at the time of reading a document.

(B) Scan (image reading) The first mirror table 1206 and the second mirror table 1207 are moved to read a document image two-dimensionally.

When reading of the original image is completed, the timing belt 1202 and the mirror driving shaft 120 are driven by driving the original scanner motor 1201 for the next image reading.
3. The first mirror base 1206 and the second mirror base 1207 are moved in opposite directions via the wires 1204 and 1205 (B
ack).

[0011]

However, in a conventional image reading apparatus, when a discharge light emitting type light source such as a fluorescent lamp or a xenon tube is used as a light source for illuminating a document, as shown in FIG. 14 and FIG. Problems arise. 14 and 15 show general characteristics of a discharge light emitting type light source. FIG. 14 shows a state in which the light amount gradually decreases from (A) the initial lighting amount immediately after the start of lighting of the light source according to the continuous lighting time, and (B) changes to the stable lighting amount. FIG. 15 shows a characteristic example of a three-wavelength type discharge light source used for reading a color image. In this case, the time until the stable light amount is reached and the amount of change from the initial light amount are R (red), G
(Green), B (blue).

As described above, when a discharge-type illumination light source is used as the light source for illuminating the original of the image reading apparatus, the continuous lighting time light amount or each of the R, G, and B light amounts gradually changes. It is difficult to always maintain a constant state, and a reading density variation, a reading color variation, and the like are caused. In particular, when such an image reading apparatus is used in a copying machine or a color copying machine, the density and color of the copied image become unstable, which is a serious problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide an image reading apparatus, an image reading method, and a storage medium capable of considerably reducing reading density fluctuation and reading color fluctuation. The first purpose.

Further, the present invention has been made in view of the above points, and an image reading apparatus and an image reading method in which the use of the image reading apparatus of the present invention in a copying machine hardly affects a reduction in copy speed. And providing a storage medium.

[0015]

According to a first aspect of the present invention, there is provided an image reading apparatus having a reference white plate for shading correction. A light quantity varying means for varying the light quantity, and a control means for changing a light quantity control value for the light quantity varying means according to a signal level when the reference white plate is read.

According to another aspect of the present invention, there is provided an image reading apparatus having a reference white plate for shading correction, wherein a gain variable means for amplifying an image read signal to an appropriate signal level. And control means for changing a gain control value for the gain variable means according to a signal level when the reference white plate is read.

According to a third aspect of the present invention, there is provided an image reading apparatus having a reference white plate for shading correction, wherein a light amount for illuminating a document is changed to an appropriate light amount. Means, a gain varying means for amplifying an image reading signal to an appropriate signal level, and a light quantity control value for the light quantity varying means in accordance with a signal level when the reference white plate is read, and a gain controlling means for the gain varying means. Control means for changing the gain control value.

According to another aspect of the present invention, there is provided a document illuminating means for illuminating a document, an image reading means for converting light reflected from the document or the reference white plate into an electric signal, A shading correction unit for performing shading correction based on data obtained by reading the reference white plate by the image reading unit.

According to a fifth aspect of the present invention, there is provided the document illuminating means according to a signal level when the image reading means reads the reference white plate. It is characterized in that the amount of change of the parameter for determining the amount of light can be arbitrarily set.

In order to achieve the above object, the present invention according to claim 6, wherein the gain varying means is configured to read the reference white plate by the image reading means according to a signal level.
The amount of change in gain control for the gain variable means can be set arbitrarily.

In order to achieve the above object, the present invention according to claim 7 is applicable to a copying machine, and updates the light quantity control value and the gain control value when the light quantity and the gain are almost appropriate. It is characterized in that it is after the next image reading.

According to another aspect of the present invention, there is provided an image reading method applied to an image reading apparatus having a reference white plate for shading correction. And a control step of changing a light amount control value for the light amount variable step in accordance with a signal level when the reference white plate is read.

According to a ninth aspect of the present invention, there is provided an image reading method applied to an image reading apparatus having a reference white plate for shading correction, the method comprising: And a control step of changing a gain control value for the gain variable step according to a signal level when the reference white plate is read.

According to a tenth aspect of the present invention, there is provided an image reading method applied to an image reading apparatus having a reference white plate for shading correction.
A light quantity varying step for varying the light quantity for illuminating the original to an appropriate light quantity, a gain varying step for amplifying the image reading signal to an appropriate signal level, and the light quantity varying according to the signal level when reading the reference white plate And a control step of changing a light control value for the step and changing a gain control value for the variable gain step.

To achieve the above object, according to the present invention, there is provided a document illuminating step of illuminating a document, an image reading step of converting reflected light from the document or the reference white plate into an electric signal, A shading correction step of performing shading correction based on data obtained by reading the reference white plate in the image reading step.

According to a twelfth aspect of the present invention, in the twelfth aspect of the present invention, in the light amount changing step, the original illuminating step is performed according to a signal level when the reference white plate is read in the image reading step. It is characterized in that the amount of change of the parameter for determining the amount of light can be arbitrarily set.

According to a thirteenth aspect of the present invention, in the gain variable step, the gain variable step is performed according to a signal level when the reference white plate is read in the image reading step. The amount of change of the gain control with respect to can be set arbitrarily.

In order to achieve the above object, the present invention according to claim 14 is applicable to a copying machine, and updates the light amount control value and the gain control value when the light amount and the gain are almost appropriate. It is characterized in that it is after the next image reading.

In order to achieve the above object, the present invention according to claim 15 is readable by a computer storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction. A light amount varying step of varying an amount of light illuminating the original to an appropriate amount of light,
A control step of changing a light amount control value for the light amount variable step according to a signal level when the reference white plate is read.

In order to achieve the above object, the present invention according to claim 16 is readable by a computer storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction. Wherein the image reading method comprises: a gain variable step of amplifying an image read signal to an appropriate signal level; and a gain control for the gain variable step in accordance with a signal level when the reference white plate is read. And a control step of changing a value.

In order to achieve the above object, the present invention according to claim 17 is readable by a computer storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction. A light amount varying step of varying an amount of light illuminating the original to an appropriate amount of light,
A variable gain step for amplifying the image reading signal to an appropriate signal level; and a variable light quantity control value for the variable light quantity step according to the signal level when the reference white plate is read, and a gain control value for the variable gain step. And a control step of changing

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a main part of an image reading apparatus according to an embodiment of the present invention. The image reading device according to the embodiment of the present invention includes an image sensor 10
1, variable gain amplifiers 102, 103, 104, A / D
Converters 105, 106, 107, shading correction circuit 108, line memory 109, illumination light source 110, lamp power supply 111, CPU 112, platen glass on which a document as shown in FIG. 11 is placed, reference white plate ,
It is configured to include a dummy glass (not shown) provided with a reference white plate.

The image sensor 101 forms an image on the light receiving surface of the reflected light from the document irradiated with the light from the illumination light source 110, and generates an electric signal (R, G,
B). Further, the image sensor 101 reads a reference white plate when obtaining shading correction data, and outputs it to the variable gain amplifiers 102, 103, 104. The variable gain amplifiers 102, 103, and 104 output electric signals (R, G,
B) is amplified so as to have an appropriate signal amplitude, and output to A / D converters 105, 106, and 107. A / D converter 1
05, 106 and 107 are variable gain amplifiers 102, 1
The electric signals (R, G, B) amplified by the circuits 03 and 104 are converted into digital signals in signal units of light receiving pixels on the light receiving surface of the image sensor 101, and the shading correction circuit 10
8. Output to the line memory 109.

The shading correction circuit 108 has an A / D
The converters 105, 106, and 107 perform shading correction calculations on the digitized electric signals (R, G, and B), and output original reading signals (R, G, and B). line·
The memory 109 stores shading correction data used in the shading correction calculation in the shading correction circuit 108. As the shading correction data, image data obtained by reading a reference white plate (however, before shading correction) is used. use. The illumination light source 110 is a light source for illuminating a document or a reference white plate. When the CPU 112 controls the lamp power supply 111, the switching between ON / OFF and the illumination light amount change.
The lamp power supply 111 is a power supply that supplies electric power to the illumination light source 110 and can vary the amount of illumination light.

The CPU 112 controls the variable gain amplifier 10
2, 103 and 104, a central processing unit for controlling the lamp power supply 111 and the line memory 109, based on a control program according to the present invention stored in the image reading apparatus or supplied from outside the image reading apparatus. 3 to 6 are executed. As a method of externally supplying the control program of the present invention to the image reading apparatus according to the embodiment of the present invention, a storage medium (floppy disk, CD-ROM) storing the control program of the present invention is used.
A storage medium such as a ROM) is inserted into a storage medium drive of a computer, and the control program of the present invention read from the storage medium is supplied to the image reading apparatus.

The correspondence between the components in the claims and the components of the image reading apparatus according to the embodiment of the present invention is as follows. Image reading means in the claims corresponds to the image sensor 101,
The variable gain means in the claims corresponds to the variable gain amplifiers 102, 103 and 104, the shading correction means in the claims corresponds to the shading correction circuit 108, and the document illuminating means in the claims corresponds to the illumination light source 110. The variable light amount means in the claims corresponds to the lamp power supply 111, and the control means in the claims corresponds to the CPU 112.

Next, an image reading operation and shading correction of the image reading apparatus according to the embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS.
FIG. 2 is an explanatory diagram showing shading correction of the image reading apparatus.

In the image reading apparatus, the illumination light source 110 is controlled by the CPU 112 controlling the lamp power supply 111.
The switching of the light on / off and the illumination light amount change. The reflected light from the document irradiated with light from the illumination light source 110 forms an image on the light receiving surface of the image sensor 101, is converted into electric signals (R, G, B), and is output from the image sensor 101. R output from the image sensor 101,
Since the G and B signals are analog signals, they are amplified by the variable gain amplifiers 102, 103, and 104 to have appropriate signal amplitudes. Each variable gain amplifier 102, 1
R, G, and B signals amplified at 03 and 104 are A
The signals are converted into digital signals by the / D converters 105, 106, and 107 in signal units of each light receiving pixel on the light receiving surface of the image sensor 101.

The R, G, and B signals digitized by the A / D converters 105, 106, and 107 are input to a shading correction circuit 108, and the result of the shading correction calculation is output from the shading correction circuit 108. , Original reading signals (R, G, B). As described above, the line memory 109 stores the shading correction circuit 1
The shading correction data used in the shading correction calculation in step 08 is stored. As the shading correction data, image data obtained by reading a reference white plate (however, before shading correction) is used.

Next, the shading correction circuit 108
The contents of the shading correction calculation performed in (1) below
It is shown in the formula.

SHi = [SH-TAR / Wi] × Si (1) where, i: pixel No. SHi: image data after shading correction Si: image data before shading correction Wi: reference white plate reading SH-TAR: target value of shading correction SH-TAR: target value of shading correction By performing the above equation (1) for each of R, G, and B signals and each pixel, as shown in FIG. Shading correction is performed. In FIG. 2, a waveform indicated by a solid line is a reading waveform of the reference white plate (but before shading correction) when the horizontal axis is the main scanning direction (pixel arrangement in the image sensor 101). By performing the shading correction calculation of the equation (1), image data as shown by the broken line in FIG. 2 can be obtained.

Next, a method for correcting the amount of light of the illumination light source 110 in the image reading apparatus according to the embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS. 1, 3 and 4, FIGS. explain. 3 and 4 are flowcharts showing the light amount correction control of the image reading device, and FIGS. 7 and 8 are explanatory diagrams showing the relationship between the change amount of LAMP-DATA and the value of ND of the image reading device.

In FIG. 3 and FIG. 4, step S301
Then, from the image data (stored in the line memory 109) at the time of the (N-1) th shading sample (reading of the reference white plate), the maximum values Rmax, Gmax, Rmax, Gmax, The CPU 112 detects Bmax by checking the contents of the line memory 109. Step S
In 302, the CPU 112 calculates the following equation (2) between Rmax, Gmax, Bmax detected in step S301 and a predetermined coefficient, and obtains an ND value as a result.

ND = α · Rmax + β · Gmax + γ · Bmax Expression (2) (The above three coefficients α, β, and γ include “φ” and can take any value. In step S303, the CPU 112 determines whether the value of ND calculated in step S302 is smaller than a predetermined value K1. In the above step S303, “ND <K
If it is 1 ", the CPU 112 determines that the amount of light tends to be insufficient. In step S307, the parameter (hereinafter, LAMP-DATA) for determining the amount of lamp light is increased by a predetermined value, and the Nth and subsequent shading samples are performed. On the other hand, if “ND ≧ K1” in step S303, the next determination process is performed in step S304.

In step S304, the CPU 112
It is determined whether the value of ND is greater than a predetermined value K2.
If “ND> K2” in step S304,
The CPU 112 determines that the amount of light tends to be too large,
In step S306, LAMP-DATA is reduced by a predetermined amount and used as the NAMP and subsequent shading samples and LAMP-DATA at the time of image reading. On the other hand, if “ND ≦ K2” in step S304, K1 ≦ N when combined with the determination result in step S303.
It follows that D ≦ K2. In this case, it is determined that the light amount is in an appropriate state, and the LAMP-DATA is not changed (updated).

As described above, in the light amount correction control shown in the flowcharts of FIGS. 3 and 4, as shown in FIG. 7, the values of ND are (1) to (3) below: (1) ND <K1 (2) ) K1 ≦ ND ≦ K2 (3) Depending on the range of K2 <ND, the update of LAMP-DATA is switched to “increase by a certain amount”, “decrease by a certain amount”, or “no change”. Was. If this idea is developed, a method of arbitrarily setting the change amount of LAMP-DATA according to the obtained ND value, as shown in FIG. 8, for example, can be easily considered.

Next, a method of correcting the gain of the R, G, and B variable gain amplifiers 102, 103, and 104 in the image reading apparatus according to the embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS. This will be described with reference to FIGS. 6, 9, and 10. 5 and 6 are flowcharts showing the amplifier gain correction control of the image reading apparatus, and FIGS. 9 and 10 are explanatory diagrams showing the relationship between the amount of change of the amplifier gain of the image reading apparatus and the value of Smax. 5 and 6 show R, G, B
Among the channels, R,
It is assumed that gain correction control is performed independently for each of G and B.

In FIGS. 5 and 6, step S501 is performed.
Then, the CPU 112 detects the signal Smax of the maximum signal level from the reference white plate read data at the time of the (N-1) th shading sample. Step S502
Then, the CPU 112 compares Smax detected in step S501 with the predetermined value LS1. Step S above
If “Smax <LS1” in 502, the CPU 112
Determines that the amplifier gain tends to be insufficient, and in step S506, increases the corresponding amplifier gain by a predetermined amount and uses it as the Nth and subsequent shading samples and the amplifier gain at the time of image reading. Conversely, if “Smax ≧ LS1” in step S502, the following determination processing is performed in step S503.

In step S503, the CPU 112
The value of Smax is compared with a predetermined value LS2. If “Smax> LS2” in step S503, the CPU 112
Determines that the amplifier gain is too large, and determines in step S5
At 07, the corresponding amplifier gain is reduced by a predetermined amount, and N
It is used as a shading sample for the second and subsequent times and as an amplifier gain at the time of image reading. On the other hand, step S5
03, if “Smax ≦ LS2”, step S5
02 and “LS1 ≦ Smax ≦ L
In this case, it is determined that the amplifier gain is in an almost appropriate state, and the amplifier gain is not changed (updated).

As described above, the correction control of the amplifier gain shown in the flowcharts of FIGS.
The amplifier gain control amount is updated according to the range of (1) to (3) below, that is, (1) Smax <LS1 (2) LS1 ≦ Smax ≦ LS2 (3) LS2 <Smax Is switched to "increase by a certain amount", "decrease by a certain amount", or "do not change". If this idea is developed, a method of arbitrarily setting the change amount of the amplifier gain control according to the obtained value of Smax, as shown in FIG. 10, for example, can be easily considered.

In the above embodiment of the present invention,
Although the image reading apparatus itself has been described, the image reading apparatus of the present invention is used as a copying machine (monochrome copying machine, color copying machine).
Can be applied to the image reading unit.

As described above, according to the image reading apparatus of the embodiment of the present invention, the illumination light source 110 for illuminating the original and the image sensor for converting the reflected light from the original or the reference white plate into an electric signal. 101 and illumination light source 110
Lamp power supply 111 for varying the amount of light radiated from the light source to an appropriate amount, and variable gain amplifiers 102 to 10 for amplifying an output signal from the image sensor 101 to an appropriate signal level.
4 and a CPU 112 that changes the light amount control value for the lamp power supply 111 and the gain control value for the variable gain amplifiers 102 to 104 in accordance with the signal level when the reference white plate is read. Acts and effects.

In the above configuration, the CPU of the image reading device
112, at the time of the light amount correction control, when the maximum value Rmax, Gmax, Bmax of each of the R, G, B signals and the calculation result ND of the predetermined coefficient are ND <K1, it is determined that the light amount tends to be insufficient, Parameters (LAM
P-DATA) is increased by a predetermined value and used as the NAMP shading sample and LAMP-DATA at the time of image reading. If ND> K2, it is determined that the amount of light tends to be too large, and LAMP-DATA is reduced by a predetermined amount.
Used as LAMP-DATA at the time of image reading and the Nth and subsequent shading samples. K1 ≦ ND ≦ K
In the case of 2, it is determined that the light quantity is in an almost appropriate state, and LA
No change (update) of MP-DATA is performed.

Further, during the amplifier gain correction control, (N−
1) The maximum signal level signal Sma detected from the reference white plate read data at the time of the first shading sample
If x is Smax <LS1, it is determined that the amplifier gain tends to be insufficient, and the amplifier gain is increased by a predetermined amount.
It is used as a shading sample for the second and subsequent times and as an amplifier gain at the time of image reading. In the case of “Smax> LS2”, it is determined that the amplifier gain is too large, and the corresponding amplifier gain is reduced by a predetermined amount and used as the Nth and subsequent shading samples and the amplifier gain at the time of image reading. When LS1 ≦ Smax ≦ LS2, it is determined that the amplifier gain is almost in an appropriate state, and the amplifier gain is not changed (updated).

That is, in the embodiment of the present invention, the lighting energy supplied from the lamp power supply 111 to the illumination light source 110 and the output energy from the image sensor 101 are used to respond to the light amount variation and tint variation of the illumination light source 110 in the image reading apparatus. Since the amplifier gain for amplifying the signal to be amplified can be followed by sequential control, there is an effect that it is possible to considerably reduce the reading density fluctuation and the reading color fluctuation, which are the conventional problems.

Further, in the embodiment of the present invention, the necessary light amount control amount and each amplifier gain are updated after the next image reading, so that the image reading apparatus of the present invention is used in a copying machine. However, there is an effect that it is possible to reduce the influence on the reduction of the copy speed.

The present invention may be applied to a system constituted by a plurality of devices or to an apparatus constituted by a single device. A storage medium storing software program codes 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 executes the program code stored in the storage medium. Needless to say, this can also be achieved by executing the reading.

In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS and the like running on the computer are actually executed based on the instructions of the program code. It goes without saying that a part or all of the above-described processing is performed, and the functions of the above-described embodiments are realized by the processing.

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, based on the instruction of the program code, It goes without saying that the CPU included in the function expansion 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.

[0063]

As described above, according to the image reading apparatus of the first aspect, the light quantity variation means supplies the document illumination means to the light quantity fluctuation and the tint fluctuation of the document illumination means in the image reading apparatus. Since the lighting energy can be made to follow the sequential control, there is an effect that it is possible to considerably reduce the fluctuation of the reading density and the fluctuation of the reading color, which are the conventional problems.

Further, according to the image reading apparatus of the present invention, a gain varying means for amplifying a signal output from the image reading means in response to a variation in light amount and a change in tint of the original illuminating means in the image reading apparatus. Can be tracked by sequential control, so that there is an effect that it is possible to considerably reduce the reading density fluctuation and the reading tint fluctuation, which are the conventional problems.

According to the image reading apparatus of the present invention, the lighting energy supplied from the light quantity varying means to the document illuminating means for the light quantity fluctuation and the tint fluctuation of the document illuminating means in the image reading apparatus, and Since the gain of the gain variable means for amplifying the signal output from the image reading means can be made to follow by the sequential control, it is possible to considerably reduce the reading density fluctuation and the reading color fluctuation which are the conventional problems. effective.

According to the image reading apparatus of the seventh aspect, the image reading apparatus is applicable to a copying machine, and in addition to having the same effects as those of the image reading apparatuses of the first to sixth aspects, it is necessary to By updating the light amount control amount and the gain of the gain variable unit after the next image reading, even when the image reading apparatus of the present invention is applied to a copying machine, it is possible to reduce the influence on the reduction of the copying speed. This has the effect.

According to the image reading method of the present invention, the light amount variation and the tint variation in the document illumination step in the image reading apparatus to which the image reading method is applied are supplied from the light amount variable step to the document illumination step. Since the lighting energy that follows can be made to follow the sequential control, there is an effect that it is possible to considerably reduce the fluctuation of the reading density and the fluctuation of the reading tint which are the conventional problems.

According to the image reading method of the ninth aspect, a signal output from the image reading step is provided in response to a light amount variation and a tint variation in an original illumination step in an image reading apparatus to which the image reading method is applied. Since the gain of the variable gain step for amplifying can be followed by sequential control, there is an effect that it is possible to considerably reduce the reading density fluctuation and the reading tint fluctuation, which are conventional problems.

According to the image reading method of the present invention, the light amount change and the tint change in the original illuminating step in the image reading apparatus to which the image reading method is applied are changed from the light amount varying step to the original illuminating step. And the gain of the variable gain step for amplifying the signal output from the image reading step can be followed by sequential control, so that the conventional problems of reading density fluctuation and reading color fluctuation can be considerably reduced. There is an effect that can be reduced.

Further, according to the image reading method of the present invention, the image reading method is applicable to a copying machine. By updating the light amount control amount and the gain of the variable gain step after the next image reading, it is possible to reduce the influence of the copy speed reduction even when the image reading method of the present invention is applied to a copying machine. This has the effect.

Further, according to the storage medium of the present invention, the image reading method is read from the storage medium and executed by the image reading apparatus, so that the light quantity fluctuation and the tint fluctuation in the document illumination step in the image reading apparatus can be reduced. Since the lighting energy supplied from the light amount changing step to the document illuminating step can be made to follow the sequential control, there is an effect that it is possible to considerably reduce the reading density fluctuation and the reading color fluctuation which are the conventional problems.

According to the storage medium of the sixteenth aspect, the image reading method is read from the storage medium and executed by the image reading device, so that the light amount variation and the tint variation in the document illumination step in the image reading device can be reduced. Since the gain of the variable gain step for amplifying the signal output from the image reading step can be followed by sequential control, it is possible to considerably reduce the reading density fluctuation and the reading color fluctuation which are the conventional problems. There is an effect.

According to the storage medium of the present invention, the image reading method is read out from the storage medium and executed by the image reading apparatus, so that the light amount fluctuation and the tint fluctuation in the document illumination step in the image reading apparatus can be reduced. Lighting energy supplied from the light amount variable step to the document illumination step,
In addition, since the gain of the variable gain step for amplifying the signal output from the image reading step can be followed by the sequential control, it is possible to considerably reduce the conventional problems of reading density fluctuation and reading color fluctuation. There is an effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing shading correction of the image reading device according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating light amount correction control of the image reading apparatus according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating light amount correction control of the image reading apparatus according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating amplifier gain correction control of the image reading apparatus according to the embodiment of the present invention.

FIG. 6 is a flowchart illustrating amplifier gain correction control of the image reading apparatus according to the embodiment of the present invention.

FIG. 7 is an LA of the image reading apparatus according to the embodiment of the present invention;
FIG. 9 is an explanatory diagram showing a relationship between a change amount of MP-DATA and a value of ND.

FIG. 8 illustrates an LA of the image reading apparatus according to the embodiment of the present invention.
FIG. 9 is an explanatory diagram showing a relationship between a change amount of MP-DATA and a value of ND.

FIG. 9 is an explanatory diagram showing a relationship between a change amount of an amplifier gain and a value of Smax in the image reading apparatus according to the embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a relationship between a change amount of an amplifier gain and a value of Smax in the image reading apparatus according to the embodiment of the present invention.

FIG. 11 is a schematic diagram illustrating a configuration of an image reading system of an image reading apparatus according to a conventional example.

FIG. 12 is a perspective view illustrating a configuration of a scanning mechanism of an image reading apparatus according to a conventional example.

FIG. 13 is an explanatory diagram showing an example of an image reading sequence of an image reading apparatus according to a conventional example.

FIG. 14 is an explanatory diagram showing a characteristic example of a discharge type light source.

FIG. 15 is an explanatory diagram showing a characteristic example of a discharge type light source.

[Explanation of symbols]

 Reference Signs List 101 Image sensor 102, 103, 104 Variable gain amplifier 108 Shading correction circuit 110 Illumination light source 111 Lamp power supply 112 CPU

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/40 101A F-term (Reference) 2H110 AA01 BA13 BA17 CB76 CC11 CE02 5B047 AA01 AB04 BC11 CB04 DA01 DA04 DC06 5C072 AA01 BA04 BA08 BA19 CA02 CA14 EA04 FB12 RA16 UA02 UA05 UA12 XA01 5C077 LL04 PP72 PQ03

Claims (17)

[Claims] 1. An image reading apparatus having a reference white plate for shading correction, comprising: a light amount varying means for varying a light amount for illuminating a document to an appropriate light amount; and a signal level when the reference white plate is read. Control means for changing a light amount control value for the light amount variable means in response to the change. 2. An image reading apparatus having a reference white plate for shading correction, comprising: a gain varying means for amplifying an image read signal to an appropriate signal level; and a signal level when the reference white plate is read. And a control unit for changing a gain control value for the gain variable unit. 3. An image reading apparatus having a reference white plate for shading correction, comprising: a light amount varying means for varying an amount of light illuminating a document to an appropriate amount; and a gain for amplifying an image reading signal to an appropriate signal level. Variable means, and control means for changing a light quantity control value for the light quantity variable means according to a signal level when the reference white plate is read, and changing a gain control value for the gain variable means. Image reading device. 4. An original illuminating unit for illuminating an original, an image reading unit for converting reflected light from the original or the reference white plate into an electric signal, and a data read from the reference white plate by the image reading unit. 2. A shading correction means for performing shading correction.
The image reading device according to any one of claims 1 to 3. 5. The light amount varying means according to a signal level when the reference white plate is read by the image reading means.
4. The method according to claim 1, wherein a change amount of a parameter for determining a light amount of the document illuminating means can be arbitrarily set.
5. The image reading device according to any one of 4. 6. The gain changing means can arbitrarily set a change amount of gain control for the gain changing means in accordance with a signal level when the image reading means reads the reference white plate. 5. The method according to claim 2, wherein
The image reading device according to any one of the above. 7. The apparatus according to claim 1, wherein the light amount control value and the gain control value are updated after the next image reading when the light amount and the gain are substantially appropriate. 7. The image reading device according to any one of claims 1 to 6. 8. An image reading method applied to an image reading apparatus having a reference white plate for shading correction, comprising: a light amount changing step of changing a light amount for illuminating a document to an appropriate light amount; A control step of changing a light quantity control value for the light quantity variable step according to a signal level at the time of reading. 9. An image reading method applied to an image reading apparatus having a reference white plate for shading correction, comprising: a gain variable step of amplifying an image read signal to an appropriate signal level; and reading the reference white plate. A control step of changing a gain control value for the gain variable step according to a signal level at the time of the image reading. 10. An image reading method applied to an image reading apparatus having a reference white plate for shading correction, comprising: a light amount changing step of changing a light amount for illuminating a document to an appropriate light amount; A variable gain step for amplifying the signal level to an appropriate signal level, and a control step for changing a light quantity control value for the variable light quantity step and a gain control value for the variable gain step according to the signal level when the reference white plate is read. An image reading method comprising: 11. A document illuminating step of illuminating a document,
An image reading step of converting reflected light from a document or the reference white plate into an electric signal, and a shading correction step of performing shading correction based on data obtained by reading the reference white plate in the image reading step. The image reading method according to claim 8. 12. In the light amount changing step, a change amount of a parameter for determining a light amount in the document illumination step can be arbitrarily set according to a signal level when the reference white plate is read in the image reading step. The image reading method according to any one of claims 8, 10, and 11, wherein: 13. The variable gain step, wherein a change amount of gain control for the variable gain step can be arbitrarily set according to a signal level when the reference white plate is read in the image reading step. The image reading method according to any one of claims 9 to 11, wherein: 14. The method according to claim 8, wherein the light amount control value and the gain control value are updated after the next image reading when the light amount and the gain are substantially appropriate. 14. The image reading method according to any one of claims 13 to 13. 15. A storage medium readable by a computer storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction, wherein the image reading method includes the steps of: A light amount changing step of changing an illuminating light amount to an appropriate light amount; and a control step of changing a light amount control value for the light amount changing step in accordance with a signal level when the reference white plate is read. Storage medium. 16. A computer-readable storage medium storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction, wherein the image reading method includes an image reading method. A memory, comprising: a gain variable step of amplifying a signal to an appropriate signal level; and a control step of changing a gain control value for the gain variable step according to a signal level when the reference white plate is read. Medium. 17. A storage medium readable by a computer storing a program for executing an image reading method applied to an image reading apparatus having a reference white plate for shading correction, wherein the image reading method includes the steps of: A light amount varying step of varying an illuminating light amount to an appropriate light amount; a gain varying step of amplifying an image reading signal to an appropriate signal level; A control step of changing a light amount control value and changing a gain control value for the gain variable step.