JP2003125176A - Flat bed type scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat bed type scanner capable of realizing correction of uneven luminous quantity of a surface light source even with a simple hardware configuration. SOLUTION: The flat bed type scanner, which has an optical unit provided with a line sensor movably placed along the face of an original set to a prescribed position and applying photoelectric conversion to an incident light into an electric signal, is provided with a surface light source unit placed opposite to the optical unit with the original and an original platen glass plate inbetween and emitting a light to a transparent original; a means for acquiring and storing line shading correction data in the main scanning direction; a means for acquiring and storing area shading correction data of the original face; and a means for using either or both of the two kinds of shading correction data to conduct shading correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flatbed type scanner device for reading a reflection-type and transmission-type document image set at a predetermined position.

[0002]

2. Description of the Related Art In general, a flatbed type scanner device has a two-dimensional structure which is obtained by scanning a one-dimensional sensor in a sub-scanning direction.
Reading a three-dimensional image. An optical unit called a carriage or the like is a light source for illuminating a document, optical parts such as lenses and mirrors for forming reflected light or transmitted light on a sensor, an image sensor in which elements for photoelectrically converting light into electric signals are arranged. Composed of. In such a unit, shading occurs due to uneven distribution of the characteristics of the lens, uneven sensitivity of the image sensor, etc. Therefore, when reading a reflective original, it is usually set outside the original reading range before starting reading. A white plate of uniform density called a standard white plate is read, shading correction data is generated, and an image is read while performing shading correction.

Further, when reading a transparent original, the light source of the surface light source unit set on the upper side of the original glass is used for reading, but a shield such as an original is placed outside the original reading range. An area for acquiring the prohibited shading data is provided, and shading correction is performed using data generated based on the data obtained by reading the range.

[0004]

When reading a reflective original, the system from the light source to the image sensor moves integrally in the sub-scanning direction, so shading with a two-dimensional spread is unlikely to occur. . Strictly speaking, the amount of light from the light source fluctuates, but it is possible to perform practically sufficient correction by performing level correction for each line.

However, the flat light source used for reading the transparent original has a system in which fluorescent lamps, which are originally linear light emitters, are arranged, and a flat light source is spread by using a light guide plate or the like. It has a structure in which unevenness in the amount of light having a two-dimensional spread is likely to occur. Therefore, the line shading represented by the data obtained in the shading data acquisition area as described above cannot completely correct the unevenness of the light amount of the planar light source, and the uneven density appears in the image. That is, two-dimensional shading correction is required.

Therefore, it is necessary to obtain shading correction data in the entire original reading range.
If this is done for all pixels as in the case of line shading, the amount of data becomes enormous and a large amount of memory becomes necessary. Therefore, as a conventional example, a method is known in which line shading and area shading are performed separately.

As described above, shading has variations in pixel sensitivity of the sensor and uneven light amount distribution of the surface light source.
In the former case, shading correction is required for each pixel because it is discontinuous for each pixel, but it is sufficient if the sensor for one line has correction data for one line. On the other hand, the latter shows continuous and smooth shading characteristics, but 2
Dimensional correction data is needed.

As described above, paying attention to the difference in the characteristics of the shading itself, the line shading for correcting the shading of the sensor and the area shading for correcting the shading of the surface light source are processed by different circuits, and the area shading correction data is obtained. Takes a wide sampling point interval and corrects with a representative value to reduce the amount of memory.

However, the area shading correction requires a correction that changes in the sub-scanning direction, which causes a problem that the hardware configuration becomes complicated. Further, since the line shading correction data and the area shading correction data were acquired separately, it was a troublesome work twice.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a flatbed type scanner device capable of correcting unevenness in light amount of a surface light source with a simple hardware configuration. .

[0011]

In order to achieve the above object, the present invention is provided so as to be movable along a document surface of a document set at a predetermined position, and photoelectrically converts incident light into an electric signal. In a flatbed scanner device including an optical unit including a line sensor for conversion, a flat light source unit for irradiating a transmissive original is disposed in a direction opposite to the optical unit with the original and the platen glass sandwiched, and a flat light source unit for main scanning direction. Shading correction is performed using one or both of the two types of shading correction data, a unit for acquiring and storing the line shading correction data, a unit for acquiring and storing the area shading correction data of the document surface. It is characterized in that means for performing is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a block diagram showing the configuration of a flatbed type scanner device according to the present invention. In FIG. 2, 201 is a scanner body and 202 is a scanner body 20.
1, a transparent original unit having a surface light source for reading a transparent original set above 1, and 203 is an image sensor for converting image information into an electric signal by photoelectrically converting light.

Reference numeral 204 denotes an analog circuit for applying analog processing to the image signal output from the image sensor 203, further A / D converting it, and sending the digitized image signal to the subsequent stage.
Reference numeral 05 denotes a digital circuit for processing a digital image signal, 20
Reference numeral 6 is a RAM for storing various data such as image signals and correction data.

Reference numeral 207 is a CP for controlling the entire scanner.
U and 208 are ROMs that store information describing the operation sequence of the CPU 207, 209 is a motor drive circuit that controls the motor that moves the optical unit, and 210 is an I / F circuit that communicates with the host computer.

Reference numeral 211 denotes a flat light emitting body, which is a flat light source unit for irradiating the transparent original with light. 212
Is a lamp-in park for causing the flat light source unit to emit light.

FIG. 3 is a schematic cross-sectional view of a flat bed type scanner device according to the present invention. In FIG. 3, 301 is an image reading device body for reading a reflective original, 302 is an upper part of the image reading device 301, and is transparent. It is a transparent document unit that enables the reading of documents. A transparent original such as a film is arranged in the 303 part. Reference numeral 304 denotes a flat light source unit that emits flat light, and reference numeral 305 denotes an in-park unit for lighting a lamp in the flat light source unit 304.

Reference numeral 306 is a platen glass for placing a reflection original or a transmission original, and 307 is an optical unit incorporating optical system parts such as a mirror, a lens, and a CCD sensor. When reading a document on the platen glass 306, the optical unit 307 moves in the sub-scanning direction to perform reading. Thirty
Reference numeral 8 is a mirror for reflecting the light emitted from the original, and 309 is a lens unit for forming an image of the light reflected by the mirror on the sensor. Reference numeral 310 denotes a line image sensor that converts the light imaged by the optical system into an electric signal.
Is a sensor board unit on which the line image sensor 310 is mounted, 312 is a flexible flat cable that connects the sensor board unit and the main control board, and 313 is the processing of the image signal sent from the sensor board unit 311 and the entire image reading apparatus. This is the main control board that controls the.

FIG. 4 is a schematic view of the document surface of the transparent document reading unit.

In FIG. 4, reference numeral 401 denotes a transparent original unit main body, and 402 denotes an effective light source area of a light source, and the area emits illumination light. An area 403 for line shading is provided with a light source having a sufficiently flat light distribution characteristic in the main scanning direction of the sensor. 404
Is an area where the original is actually read.

FIG. 1 shows how shading correction data is generated.

A surface light source 101 emits a light source on a plane. The light amount in the effective reading area of the flat light source is read by the line sensor 102, converted into an electric signal, and stored as shading data through the analog circuit 103, the A / D converter 104, and the controller 105. Line shading correction data is the scanner body 1
It is stored in the line shading data storage memory 106 built in the 09. The area shading correction data is stored in the area shading correction data storage memory 107 built in the host computer 108.

FIG. 5 shows how shading correction is performed when a transparent original is read.

The line shading correction is performed through the line shading correction circuit on the main body side as in the reading of the reflection original. Area shading correction for surface light source correction is processed by the driver software on the host computer side. This process is not performed at the time of reading the reflection original, because it is unnecessary.

Next, the two reading modes of the reflective original reading and the transparent original reading will be described in detail with reference to the flowchart showing the flow of the image reading operation of FIG.

First, the case of reading a reflective original will be described. Upon receiving the scan start command in step 601, the image reading apparatus next determines in step 602 whether the book scan mode for reading a reflective original or the transparent mode for reading a transparent original. At the time of book scanning, line shading correction data is acquired at step 603. At this time, the image serving as the original data for calculating the shading correction data is the white reference plate provided on the back side of the platen glass. The line shading correction data is calculated as a coefficient for correcting the non-uniformity of the data when the white reference plate with uniform density is read. At the time of actual reading, several lines are read to eliminate unnecessary data and an average value is taken for the purpose of repelling defective data when dust or scratches are present on the white reference plate. The data thus calculated is stored in the line shading correction data storage memory.
Next, in step 604, scanning is started.

Next, the case of reading a transparent original will be described.

If it is determined in step 602 that the reflection original is not read, the flow advances to step 605 to enter the transparent original reading mode. In step 605, first, the surface light source is turned on with no document placed in the effective reading area, and the entire document is read. The image data obtained at this time is called shading source data.

Next, in step 606, shading correction data is calculated. At this time, both the line shading correction data and the area shading correction data are generated from the shading source data. Since the line shading appears only in the main scanning direction, only the shading component in the main scanning direction can be extracted by averaging several lines of the shading source data in the sub scanning direction. Of course, if all lines are used, the accuracy can be improved, and it is also effective to add processing such as detecting and removing unnecessary data as in the case of a reflection original. In this way, line shading correction data for each pixel is generated.

Next, regarding the area shading correction data, since the sampling point interval does not need to be every pixel, the effective reading range is divided into blocks of, for example, 16 × 16 pixel size, and for each block. 1
One data may be used as the shading correction data. At this time, the host computer that controls the scanner has the function of controlling the area shading correction, and the shading correction data is also stored in the host computer. When the preparation for shading correction is completed in this way, scanning is performed in step 604.

[0031]

As is apparent from the above description, according to the present invention, it is provided so as to be movable along the document surface of a document set at a predetermined position, and photoelectrically converts incident light into an electric signal. In a flatbed scanner device including an optical unit including a line sensor for conversion, a flat light source unit for irradiating a transmissive original is disposed in a direction opposite to the optical unit with the original and the platen glass sandwiched, and a flat light source unit for main scanning direction. Shading correction is performed using one or both of the two types of shading correction data, a unit for acquiring and storing the line shading correction data, a unit for acquiring and storing the area shading correction data of the document surface. Since the means for performing is provided, it is possible to obtain the effect that the uneven light amount correction of the surface light source can be realized with a simple hardware configuration. .

[Brief description of drawings]

FIG. 1 is a compound diagram showing how shading correction data is generated when a transparent original is read.

FIG. 2 is a block diagram showing a configuration of a flatbed type scanner device according to the present invention.

FIG. 3 is a cross-sectional view of a flatbed type scanner device according to the present invention.

FIG. 4 is a schematic view of the transparent original reading unit set above the flatbed scanner according to the present invention, as viewed from the original side.

FIG. 5 is a diagram showing how shading correction is performed when an image is read.

FIG. 6 is a flowchart showing a flow of an image reading operation.

[Explanation of symbols]

101 Surface Light Source 102 Line Sensor 103 Analog Circuit 104 A / D Converter 105 Controller 106 Line Shading Data Saving Memory 107 Area Shading Correction Data Saving Memory 108 Host Computer 201 Scanner Main Body 202 Transparent Original Document Unit 203 Image Sensor 204 Analog Circuit 205 Digital Circuit 206 RAM 207 CPU 208 ROM 209 Motor drive circuit 210 I / F circuit 301 Image reading device main body 302 Transparent original document unit 304 Flat original document unit 305 Inverter unit 306 Original table glass 307 Optical unit 308 Mirror 309 Lens unit 310 Line image sensor 311 Sensor board Unit 312 Flexible flat cable 313 Main controller Rubodo 401 transparent original unit body

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/107 H04N 1/40 101A 1/401 F term (reference) 2H108 AA01 CA01 CB01 GA02 5B047 AA01 AA05 DA04 DB01 DC07 5C072 AA01 BA08 CA02 CA14 EA05 FB12 LA02 RA15 UA02 UA05 UA11 UA13 VA03 5C077 LL04 MM27 PP06 PP08 PP10 PQ08 PQ12 PQ24 PQ25 SS01 TT06

Claims (4)

[Claims] 1. A flat bed type equipped with an optical unit provided movably along a document surface of a document set at a predetermined position and having a line sensor for photoelectrically converting incident light into an electric signal. In the scanner device, a flat light source unit that is located in the opposite direction of the optical unit with the original and the platen glass sandwiched, illuminates the transparent original, a means for acquiring and storing line shading correction data in the main scanning direction, and an original surface. Flatbed type scanner device, characterized by including means for acquiring and storing the area shading correction data of 1. and means for performing shading correction using one or both of the two types of shading correction data. . 2. When reading a reflective original, correction is performed using only shading correction data in the main scanning direction, and when reading a transparent original, both shading correction data for line shading and area shading are used. The flatbed type scanner device according to claim 1, wherein the correction is performed by performing the correction. 3. The flatbed scanner according to claim 1, wherein either one or both of the area shading data and the line shading data at the time of reading the transparent original is generated from data of an area including an effective reading range. apparatus. 4. A scanner body having line shading correction data and a line shading correction function,
2. The flatbed scanner apparatus according to claim 1, wherein the host computer has area shading correction data and an area shading correction function.