JP2000125094A - Device and method for reading image and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the influence of a back reflection phenomenon and staining on a light distribution reference surface on the quality of a read image although the light distribution reference surface is installed on a document guide surface. SOLUTION: The light distribution reference surface 24 is provided on the top surface of a document guide 23 so as to correct the illumination distribution (light distribution) at a read position of a document feeding device 2. Prior to a read of an image of a document 20, the light distribution reference surface 24 which is provided on the top surface of the document guide 23 and has reflection density of a low reflection factor is read and the reflection density of the light distribution reference surface 24 is corrected and equalized to that for a case where the light distribution reference surface 24 has a high reflection factor, thereby making the light distribution uniform.

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 an image reading apparatus having a function of reading an original surface while moving an original to be read.

[0002]

2. Description of the Related Art Conventionally, in an image reading apparatus for transferring image data to a host computer, correction of non-uniformity of an optical system and output non-uniformity of individual pixels of an image sensor, that is, so-called shading correction, is performed, and reading is performed. In order to eliminate unevenness (spots), it is common to use a white surface with a high reflectance for the document guide surface and use this white surface as a light distribution reference surface.

[0003]

In the conventional image reading apparatus as described above, when a double-sided original is read, there is a phenomenon in which the density of the back side changes, in particular, character information is shown off and affects the front side. This has led to a decrease in the accuracy of character recognition (OCR).

Further, in an image reading apparatus for reading color information, there has been a phenomenon that color reproducibility is deteriorated due to turbidity of a color affected by coloring on the back surface of a document.

Furthermore, the white light distribution reference surface provided on the surface of the document guide is easily stained, and the user often needs to clean it.

The object of the present invention is to pay attention to the above-mentioned conventional problems and to solve the problem, while the light distribution reference surface is set on the surface of the document guide, and the show-through phenomenon and the dirt on the light distribution reference surface are reduced. An object of the present invention is to provide an image reading device, an image reading method, and a storage medium that can reduce the influence on quality.

[0007]

In order to achieve the above object, an image reading apparatus according to the present invention, while moving a document,
An image reading apparatus for reading an image on a document by converting reflection density information of reflected light from an irradiated document surface into an electrical signal by a photoelectric conversion element, wherein the document is guided in a predetermined direction by defining a document position On the surface of the guide, a light distribution reference surface having a reflection density with a low reflectance in a measurable range of the light amount distribution is provided.

In one aspect of the image reading apparatus of the present invention, the reflection density of the light distribution reference surface is made uniform based on the reflection density information of the light distribution reference surface so that the light distribution at the reading position of the document is uniform. Is provided.

One embodiment of the image reading apparatus of the present invention includes a document feeding mechanism including the document guide and the light distribution reference surface, and an image reading mechanism including the photoelectric conversion element and the correction unit. The reflection density information of the light distribution reference plane stored in the transmission mechanism is communicated to the correction means of the image reading mechanism and used for calculation of reflection density correction.

According to the image reading method of the present invention, an image read on an original is converted by converting the reflection density information of the reflected light from the irradiated original surface into an electric signal by a photoelectric conversion element while moving the original. A light distribution reference surface having a reflection density of low reflectance within a measurable range of a light amount distribution provided on a surface of a document guide for defining a document position and guiding the document in a predetermined direction. The reflection density information of the light reference plane is detected, and based on the reflection density information, the reflection density of the light distribution reference plane is corrected so that the light distribution at the reading position of the document is uniform.

The storage medium of the present invention stores a computer-readable program for causing a computer to function as each component of the image reading apparatus.

The storage medium of the present invention stores a program for causing a computer to execute the image reading method in a computer-readable manner.

[0013]

In the image reading apparatus according to the present invention, prior to reading a document image, a light distribution reference surface having a low reflection reflectance provided on the document guide surface is read, and the reflection density of the light distribution reference surface is read. Is corrected to make it equivalent to the case where the light distribution reference plane has a high reflectance, and the light distribution is made uniform. That is, since a light distribution reference plane having a low reflection rate is used as a light distribution reference plane for white shading correction, show-through on the back side of the document is suppressed to be low, and density gradation information and color reproducibility on the document surface are good. In addition to reading out image data, it is possible to perform white shading correction equivalent to the case where a light distribution reference plane having a high reflectance is used.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several embodiments to which the present invention is applied will be described below in detail and specifically with reference to the drawings.

(First Embodiment) FIG. 1 is a schematic diagram showing a schematic configuration of an image reading apparatus according to a first embodiment.
In FIG. 1, reference numeral 1 denotes an image reading apparatus main body (image reading mechanism);
Denotes a document feeding device (document feeding mechanism), which is connected to the main body via an interface (not shown). 3 is a platen glass for placing the original 20 on the main body, and 4 is the original 20
5 is a first optical system unit at the main body reference position, 6 is a second optical system unit when the first optical system unit 5 is at the main body reference position, and is a document image illuminated by the light source 4. Are the first and second optical system units 5,
Through the lens unit 6, an image is formed on a photoelectric conversion element 8 such as a CCD by a lens unit 7 and converted into an electric signal. 9
Indicates that the reference position of the first optical system unit 5 is
Body reference position detection mark for detection by the signal of
Reference numeral 10 denotes a main body light distribution reference plane which is provided in the vicinity of the main body reference position detection mark 9 and is used when reading a document 20 placed on the platen glass 3.

When reading the original 20 fed by the original feeder 2, the first and second optical system units 5 and 6 first move to the reference positions 5a and 6a in the original feeder 2. Moving. Reference numeral 23 denotes a document guide provided on the document feeder 2 for defining a document position and guiding the document in a predetermined direction. The document 23 is fed by the conveyance rollers 21 and 22 along the document guide 23. Read 20. 2
Reference numeral 4 denotes a light distribution reference surface provided on the surface of the document guide 23 for correcting an illumination distribution (light distribution) at a reading position in the document feeding device 2.

FIG. 2 is a schematic diagram showing an electric block configuration of the image reading apparatus according to one embodiment of the present invention. Here, reference numeral 8 denotes a photoelectric conversion element such as a CCD for converting density information of a document image into an electric signal by photoelectric conversion, 31 denotes an amplifier circuit for amplifying an output electric signal of the photoelectric conversion element 8, and 32 denotes an amplified analog electric signal. A / that converts the
The D conversion unit 33 corrects the influence of the non-uniformity of the light amount in the image data after A / D conversion based on the correction data stored in the light amount distribution correction data storage unit 34 to make the light amount distribution uniform. A circuit 34 is a correction data memory composed of a RAM or the like for storing correction data created by the CPU 38 based on the data obtained by reading the light distribution reference surface 24, and 35 is an A / D-converted image signal having a density. An image processing unit 37 for performing correction, color correction, enlargement / reduction, etc. sends image data to an information processing device 70 such as a computer or a word processor, or the CPU 38 communicates commands and reports with the information processing device 70. , A buffer memory for temporarily storing read image data, and a control unit 38 according to the first embodiment stored in the ROM 39. Following the procedure, while using the RAM40 as a work area, and controls the image reading apparatus performs a process of sending the original image data to the information processing apparatus 70 CPU
It is.

The CPU 38 drives a motor 42 by a motor drive circuit 41 to move the first and second optical system units 5 and 6. Reference numeral 60 denotes an interface through which the CPU 38 communicates with the electric block 50 constituting the document feeder 2.

Electric block 5 constituting document feeder 2
Reference numeral 0 denotes a document sensor 52 for detecting the presence or absence of the document 20, the position of the document 20, and the like, and the transport roller 2 of the document feeder 2.
A motor 54 for driving the motors 1 and 22, a drive circuit 53 for driving the motor 54, and information of the document sensor 52 are communicated to the main body CPU 38 via the interface 60.
Alternatively, it is configured by a CPU 51 that controls the motor 54 according to a command from the main body CPU 38.

Next, an image reading procedure by light amount distribution correction using the light distribution reference plane 24 having a reflection density of low reflectance will be described.

Step 1: The CPU 38 turns on the light source 4 of the main body 1 of the image reading apparatus to turn on the main body reference position detection mark 9
Is detected by the output signal of the image sensor 8, and the reading optical systems 5 and 6 are moved in the directions A1 and A2 in FIG.

Step 2: After detecting the end position P0 of the main body reference position detection mark 9, the first and second optical system units 5 and 6 are further moved by a predetermined distance Ld on the document feeding device 2. After the original 20 is moved to the positions 5a and 6a for reading, the drive unit (not shown) of the main body is stopped.

Step 3: The image information after the A / D conversion of the light distribution reference surface 24 on the document guide 23 is stored in the buffer memory 3
Temporarily save to 6.

Step 4: The CPU 38 creates correction data of the light distribution based on the reflection density distribution data of the light distribution reference plane 24 temporarily stored in the buffer memory 36, and stores it in the correction data memory 34. At this time, the document feeder 2 is set based on a given reflection density D0adf (%) of the light distribution reference plane stored in the ROM 40 storing the program of the CPU 38.
Is corrected in the range of the light distribution reference plane 24, and D ′
Use after converting to adf. D'adf = Dadf * 100 / D0adf (1)

Step 5: After feeding the document 20 set in the document feeder 2 to the document reading position Pa, using the correction data of the light distribution on the correction data memory 34 calculated in step 4 The image is read while the light distribution is corrected by the light amount distribution correction circuit 33, and the light distribution state is corrected as in the case where the light distribution reference surface 24 is configured to have a high reflectance.

In this way, the original feeding device 2 and the image reading device main body 1 configured by using the light distribution reference surface 24 having a non-white reflection density D0adf on the surface perform proper light distribution correction. Then, the reading of the document 20 is performed.

Further, as the reflection density of the light distribution reference surface 24 increases, the amount of light reflected on the surface decreases in inverse proportion to the reflection density. By processing such as using as a representative value,
It is possible to avoid adverse effects.

As described above, according to the image reading apparatus of the first embodiment, by providing the light distribution reference surface 24 having the reflection density of low reflectance on the surface of the document guide 23, As show-through can be reduced,
It becomes possible to read image data having good density tone information and color reproducibility on the original surface.

Further, since the light distribution reference surface 24 is not a white surface having a high reflectance, the influence of dirt on the surface on the light distribution correction data is reduced, and the frequency of cleaning by the user is reduced.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a block diagram showing a schematic circuit configuration of an image reading apparatus according to another embodiment of the present invention.

Reference numeral 55 denotes a reference surface density storage device for storing the reflection density D0adf of the light distribution reference surface of the document feeder, such as an electric storage device such as an EEPROM which is a nonvolatile memory, or a DIP switch. It is composed of a mechanical storage device and is installed in the document feeder 2.

Value D stored in reference plane density storage device 55
0adf is set at the time of manufacture of the document feeder 2, and the CPU 51 of the document feeder 2 transmits this value D0adf to the CPU 38 of the main body which calculates light distribution correction data via the interface 60 every time the power is turned on. Communicated. Other components are the same as in the first embodiment.

The operation of this embodiment is performed in the same manner as in the first embodiment. However, the reflection density D0adf of the light distribution reference surface 24 in the above equation (1) is added to the reference surface obtained by communication from the document feeder 2. The stored information of the density is used.

According to the second embodiment, in addition to the effects achieved by the first embodiment, the density information of the light distribution reference surface 24 is stored together with the program in the ROM 40 of the image reading apparatus main body 1. Instead, it can be stored as a unique value for each document feeder 2, so that uniform quality can be maintained while flexibly responding to changes in manufacturing conditions and improvement of functions.

In order to realize the functions of the image reading apparatus and the image reading method described in the first and second embodiments, various components of the image reading apparatus are operated and step 1 of the image reading method is performed. The program code itself for executing the steps 5 to 5 and means for supplying the program code to a computer, for example, a storage medium storing such a program code belong to the scope of the present invention.

In this case, the program code stored in the storage medium is read out by a predetermined storage / reproduction device, and the EEPROM operates. As a storage medium for storing such a program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.

When the computer executes the supplied program code, not only the functions of the respective embodiments are realized, but also the OS (operating system) or other application running on the computer in the program code. Such a program code is also included in the present invention when the functions of each embodiment are realized in cooperation with software or the like.

Further, after the supplied program code is stored in a memory provided in a function expansion board of the computer or a function expansion unit connected to the computer, the function expansion board or the function expansion unit is specified based on the instruction of the program code. The present invention also includes a system in which a CPU or the like included in the system performs part or all of actual processing, and the processing realizes the functions of the embodiments.

[0039]

According to the present invention, by providing a light distribution reference surface having a reflection density of low reflectance on the surface of a document guide of an image reading apparatus, the show-through on the back side of the document can be reduced, so that the density of the document surface can be reduced. It becomes possible to read image data with various tone information and good color reproducibility.

Further, since the light distribution reference surface is not a white surface having a high reflectance, the influence of dirt on the surface on the light distribution correction data is reduced, and the frequency of cleaning by the user is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic circuit configuration of the first embodiment of the present invention.

FIG. 3 is a block diagram illustrating a schematic circuit configuration according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading apparatus main body 2 Document feeder 3 Platen glass 4 Light source 5 First optical system unit 6 Second optical system unit 7 Lens unit 8 Photoelectric conversion element 9 Main body reference position detection mark 10 Main body light distribution reference plane 20 Original 21, 22 Conveyance Roller 23 Document Guide 24 Light Distribution Reference Surface 31 Amplification Circuit 32 A / D Converter 33 Light Amount Distribution Correction Circuit 34 Correction Data Memory 35 Image Processor 36 Buffer Memory 37 Communication I / F 38 CPU 50 Electric Block 60 Interface 70 Information processing device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H110 AA25 AC02 AC14 BA17 CC11 CD06 5C072 AA01 BA08 BA20 CA15 DA12 EA05 FB12 LA03 LA04 LA15 NA01 RA16 UA02 UA11 UA13 5C077 LL04 MM03 MM27 PP06 PP09 PP15 PP43 PP08 PP58 PP65 PRR TT06

Claims (6)

[Claims] 1. An image reading apparatus for reading an image on a document by converting reflection density information of reflected light from an irradiated document surface into an electric signal by a photoelectric conversion element while moving the document. An image reading apparatus, comprising: a light distribution reference surface having a reflection density with a low reflectance in a measurable range of a light amount distribution on a surface of a document guide for guiding the light guide in a predetermined direction. And a correction unit for correcting the reflection density of the light distribution reference plane based on the reflection density information of the light distribution reference plane so that the light distribution at the reading position of the document is uniform. The image reading device according to claim 1, wherein: 3. An original feeding mechanism including the original guide and the light distribution reference surface; and an image reading mechanism including the photoelectric conversion element and the correction unit, wherein the light distribution stored in the original feeding mechanism is provided. 3. The reflection density information of a reference surface is communicated to the correction means of the image reading mechanism and used for calculation of reflection density correction.
The image reading device according to claim 1. 4. An image reading method for reading an image on a document by converting reflection density information of reflected light from an irradiated document surface into an electric signal by a photoelectric conversion element while moving the document, Using a light distribution reference surface having a reflection density of a low reflectance within a measurable range of the light amount distribution provided on the surface of the document guide for guiding the light distribution guide in a predetermined direction, the reflection density information of the light distribution reference surface is obtained. An image reading method comprising: detecting and correcting the reflection density of the light distribution reference plane based on the reflection density information so that the light distribution at the reading position of the document is uniform. 5. A storage medium storing a program for causing a computer to function as each component of the image reading apparatus according to claim 1. 6. A storage medium storing a computer-readable program for causing a computer to execute the image reading method according to claim 4.