JPH06189075A - Image reader - Google Patents

Abstract

PURPOSE:To improve the efficiency of reading due to high-speed processing and to keep the quality of reading by reading images while switching and moving a white reference board and a size detection board to a prescribed reading position for each original. CONSTITUTION:When a shift register 109 is turned on by the passage of an original 101, shading correction processing is executed for removing shading distortion caused by illumination nonuniformity or the sensitivity nonuniformity of a CCD image sensor 116. Namely, a fluorescent lamp 134 is turned on and the surface of a white reference board 103 is illuminated in the state of turning off a solenoid 108 and moving the white reference board 103 onto contact glass 112 with the energizing force of a spring 107. The reflected light provided by this illumination is guided to the CCD image sensor 116 by a reflection mirror 115 and based on inputted information, electric shading correction processing is executed.

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 such as a digital copying machine, a facsimile machine, an image scanner, or the like, and more specifically, an automatic document feeder (hereinafter referred to as an ADF) is used to automatically convey a document. The present invention relates to an image reading apparatus that realizes high-speed processing by alternately switching each reference plate at a document reading position during shading correction and document size detection for each document.

[0002]

2. Description of the Related Art Generally, in a digital scanner (image reading device), shading correction is performed on read image information to correct light amount unevenness of a light source, sensitivity unevenness of a CCD image sensor, and the like (shading distortion). . In this case, when a fluorescent lamp or the like is used as the light source, the light amount thereof fluctuates in a fine cycle, and thus shading correction is generally executed for each original.

For the above reason, the conventional image reading apparatus has, for example, the configuration shown in FIG. In the figure, 101 is a document to be read,
Reference numeral 103 denotes a white reference plate for shading correction, which is provided outside the document transport unit to prevent stains, and reference numeral 104 denotes a blackboard for document size detection, which are individually fixed at predetermined locations. Further, 106 is a document guide that conveys the document 101 in a predetermined direction, 113 is a carriage that scans the document 101 in the horizontal direction, and the fluorescent lamp 11 mainly illuminates the document 101.
4, and a reflection mirror 115 for guiding the light reflected from the document surface by the fluorescent lamp 114 to the next CCD image sensor 116.
It consists of

The operation of the conventional image reading apparatus configured as described above will be described. When the shading correction is performed, the carriage 113 is moved to the A position to read the white reference plate 103, and when the size of the original 101 is detected, the carriage 113 is moved to the B position to move the original 101 and the blackboard 104.
Is read, and when the image is read, it is moved to the C position, and the image information of the original 101 is read. In this way, each process is sequentially executed.

Further, as a reference technical document relating to the present invention, there is disclosed a technique in which a transparent member for protecting the document size detecting surface from abrasion due to movement of the document is provided so that the outer periphery is in close contact. There is a gazette "image reading device".

[0006]

However, in the conventional image reading apparatus as described above,
Since the white reference plate is arranged outside the document transport unit, in the case of continuously reading documents, the carriage must be moved to the A position each time to execute the shading correction process for each document. I won't. In such a configuration, when it is required to read various originals at high speed in applications such as filing, it is extremely difficult to perform continuous reading at high speed, and the reading efficiency including the processing speed is poor. There was a point. Further, the white reference plate arranged like the conventional image reading apparatus becomes dirty with time, and an accurate white level cannot be obtained. That is, there is a problem in that accurate shading data cannot be obtained, which causes deterioration of the image.

The present invention has been made in view of the above, and makes it possible to execute shading correction processing and size detection for each original document, stabilize the shading level with time, and read by high-speed processing. The purpose is to improve efficiency and maintain reading quality.

[0008]

In order to achieve the above object, the present invention comprises a white reference plate serving as a reference for shading correction, and a size detecting plate serving as a reference for document size detection.
There is provided an image reading apparatus including a moving unit that moves the white reference plate and the size detection plate with respect to a reading position for each shading correction or document size detection process.

Further, it is desirable that the document size detection is executed after a lapse of a predetermined time after the moving means is turned on.

For the shading correction, it is desirable that the correction data is read after the moving means starts its operation.

A white reference plate serving as a reference for shading correction, a size detecting plate serving as a reference for detecting the original size, and the white reference plate and the size detecting plate are moved with respect to the reading position for each shading correction or original size detection. (EN) An image reading apparatus provided with a moving means for moving and a translucent sealing member arranged on the original side of the moving means.

A white reference plate serving as a reference for shading correction, a size detection plate serving as a reference for document size detection, and the white reference plate and size detection plate are moved with respect to the reading position for each shading correction or document size detection. There is provided an image reading apparatus including a moving unit for moving the cleaning unit and a cleaning member that contacts the reference surfaces of the white reference plate and the size detection plate to clean the reference surfaces.

A white reference plate serving as a reference for shading correction, a size detection plate serving as a reference for detecting an original size, and a moving means for moving the white reference plate or the size detection plate to a reading position are provided. An image reading device is provided in which a plate (size detection plate) is fixed at a reading position, and the size detection plate (white reference plate) is moved by the moving means for each shading correction or document size detection process with respect to the reading position. Is.

A white reference plate serving as a shading correction reference, a size detecting plate serving as a document size detecting reference, a moving means for moving the white reference plate or the size detecting plate to a reading position, and a moving means for moving the moving means. Along with this, there is provided a cleaning member for cleaning the white reference plate or the size detection plate, the white reference plate (size detection plate) is fixed at the reading position, and the size detection plate (white reference plate) is moved by the moving means. An image reading device is provided which moves with respect to a reading position for each shading correction or document size detection process.

A white reference plate serving as a shading correction reference, a size detecting plate serving as a document size detecting reference, a moving means for moving the white reference plate or the size detecting plate to a reading position, the moving means and the document mounting plate. And a translucent sealing member disposed between the mounting portions, the white reference plate (size detection plate) is fixed at the reading position, and the size detection plate (white reference plate) is read by the moving unit. In contrast, the present invention provides an image reading device that moves for each shading correction or document size detection process.

[0016]

In the image reading apparatus according to the present invention, during shading correction and document size detection, the white reference plate and the size detection plate are read by the moving means in a predetermined condition by the moving means while the optical system remains fixed. Achieves high-speed reading of information by switching to a position and moving to execute image reading.

Further, either the size detection plate or the white reference plate is fixed to the original reading portion, and a reference plate other than the fixed one is attached to the moving means, and the optical system is fixed during shading correction and original size detection. In this state, by moving either the white reference plate or the size detection plate for each original by the moving means, the image is read by switching to the reading position of the white reference plate or the size detection plate, Achieve high-speed reading of information.

In the above description, the cleaning member arranged in contact with each reference surface removes the adhering matter on the surface with the reciprocating movement of the moving means and always stabilizes the shading correction and the size detection state. Further, a translucent sealing member is provided on the original side of the moving means to prevent foreign matter from entering each reference surface and stabilize shading correction and size detection state.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing a main part configuration of an image reading apparatus according to the present invention. In FIG. 1, reference numeral 101 denotes a document to be read, and this apparatus is roughly composed of an ADF portion and a reading optical system. FIG. 2 is a perspective view showing the structure of this ADF. In FIGS. 1 and 2, 10
Reference numeral 2 is a reference plate attachment member, to which a white reference plate 103 for shading correction and a blackboard 104 for detecting the document size are attached.

Reference numeral 105 denotes a blackboard tension member that fixes the reference plate mounting member 102 and moves in the horizontal direction. Reference numeral 106 denotes a document guide that forms a conveyance path for the document 101. Reference numeral 107 hangs one of the document guides 106 to pull the blackboard. A spring for urging the member 105 in the horizontal direction, 108 is the blackboard tension member 10
5 is a solenoid attached so as to perform a suction operation in a direction opposite to the biasing direction of the spring 107, and 109 is an original document 10.
Registration sensors 110 and 111 for detecting the leading edge of the sheet 1 and outputting a read timing signal are conveying rollers for conveying the original 101.

The reading optical system is constructed as follows. That is, it is composed of a transparent contact glass 112 with which the surface of the original 101 is in close contact, and a carriage 113 that can scan in parallel and horizontally with respect to the surface of the contact glass 112. The lamp 114 and a reflecting mirror 115 for guiding the light reflected from the document surface by the fluorescent lamp 114 to the next CCD image sensor 116 and the like. When reading a thick original such as a book, the ADF portion is opened and the carriage 113 is horizontally scanned for reading.

FIG. 3 is an explanatory diagram showing the relationship between the optical system and the white reference plate 103 when the shading is corrected (the solenoid 108 is in the OFF state), and FIG. 4 shows the optical system and the blackboard 104 when the size is detected. It is explanatory drawing which shows a relationship (solenoid 108 is ON state). The operation of the image reading apparatus will be described with reference to FIGS. When the original 101 is set at the original setting position (not shown) and the reading process is started, the original 101 is conveyed by the conveying rollers 110 and 111, and the leading edge thereof is detected by the registration sensor 109.

When the registration sensor 109 is turned on by the passage of the original 101, shading correction processing is first executed in order to remove shading distortion caused by uneven illumination, uneven sensitivity of the CCD image sensor 116, and the like. That is, the solenoid 108 is turned off and the white reference plate 103 is moved onto the contact glass 112 by the biasing force of the spring 107 as shown in FIG. . The reflected light obtained by this illumination reflects the reflection mirror 11
The image is guided to the CCD image sensor 116 by 5 and an electrical shading correction process is executed based on the input information.

Immediately after the shading correction process is completed, as shown in FIG. 4, the solenoid 108 is turned on and the blackboard tension member 105 is moved to the right side to move the blackboard 1.
04 onto the contact glass 112 to move the original 10
The size detection operation 1 is performed. That is, the original 101
1 is conveyed onto the contact glass 112 at a predetermined speed by the rotation of the conveying roller 110 as shown in FIG. At this time, the original 101 is illuminated by the illumination of the fluorescent lamp 103, and the reflected light is reflected by the reflection mirror 115,
An image is formed on the CCD image sensor 116. In this way, the image reading of the original 101 by the original illumination and the original conveyance is executed for each line in the main scanning direction, and the entire surface is read by the movement of the original 101 in the sub scanning direction.

Next, the shading correction processing and the size detection processing will be described in more detail. FIG. 5 is a block diagram showing a schematic configuration of the image signal processing circuit according to the present invention. Reference numeral 501 is an amplifier for amplifying a signal, 502 is an A / D converter for converting an analog signal into a digital signal,
Reference numeral 503 is a selector for selecting an input signal, 504 is an image processing unit for executing predetermined image processing based on the signal input from the selector 503, 505 is a D / A converter for converting a digital signal into an analog signal, 506 Is a line memory that stores the output data from the selector 503, and 507 is a size detection unit that detects the size of the original 101.

The operation of the image signal processing circuit configured as described above will be described. As described above, the reflected light incident on the CCD image sensor 116 is photoelectrically converted depending on its intensity. The image data is amplified by the amplifier 501, input to the A / D converter 502, converted into a digital signal, and input to the selector 503.
At this time, when executing the shading correction processing,
The selector 503 is set in the B direction to output data, and the output data is stored in the line memory 506 for the designated line.

When image data is to be taken in, the selector 503 is set in the A direction to output the data, the shading data is read from the line memory 506, and this is converted into an analog signal by the D / A converter 505. After that, it is output as the reference voltage of the A / D converter 502.

When the size of the original 101 is to be detected, the selector 503 is set in the A direction and the image data is output to the size detecting unit 507 for detection. This size detection is performed by detecting the difference between the reflected lights of the original 101 portion and the background portion from the data of one line or more. Therefore, the background portion must be darker than the original 101. Therefore, a black reference plate is usually used as the background of the reading unit. Further, in the case of a manuscript 101 having a large light transmittance such as tracing paper, a reflection plate is installed on the background to make it equivalent to black, and the manuscript 101 part is captured as image data by light scattering.

FIG. 6 is a timing chart showing the first operation timing according to the present invention. In the figure, when the document 101 is conveyed, the registration sensor 109 is turned on (point A), and the leading edge of the document 101 reaches the reading position after T ₁ hour. That is, during this time T _1, it is executed in the state shown in FIG. 3 the shading correction process described above. Immediately after the shading correction process, the solenoid 108 is turned on, and the background of the document reading portion becomes the blackboard 104 for size detection as shown in FIG. Note that, generally, the solenoid 108 does not operate immediately even when an ON signal is output, and there is an operation delay.

Further, this delay time has a variation width due to variations in the solenoid 108 and mechanical parts. Therefore, the size detection start timing is the image reading start (D
The point () is not used as a reference, and the time when the solenoid 108 is turned on is used as a reference for delaying the time (T ₃ ) in consideration of variations. Therefore, it is possible to perform the size detection accurately and speedily. Next, when the image reading is completed (point E), the shading correction process is executed again, so the solenoid 108 is turned off T ₄ hours before considering the margin.

FIG. 7 is a timing chart showing the second operation timing according to the present invention. In contrast to FIG. 6, the operation timing of the solenoid 108 is advanced to perform the shading correction processing a plurality of times during the reading operation of one sheet. It makes it feasible. Here, as the size of _the original 101 becomes smaller, the time T ₅ shown in FIG. 6 can be shortened, and therefore the time for turning on the solenoid 108 (T ₁₀ ).
Then, the shading correction is executed while moving the white reference plate 103. As a result, the size detection time T ₃ ′ of the original 101 can be shortened, and T ₅ ′ is also shortened.

When the shading correction like F'is executed twice, for example, the white reference plate 103 is moved, so that the positions in the first and second shading processes are different from each other. , For example,
By averaging, the influence of dirt or the like on the surface of the white reference plate 103 can be reduced. Further, in this case, it is more effective that the number of shading corrections is as large as time permits. In addition to averaging the shading data processing, removal of abnormal peak values can be performed to achieve more reliable shading correction.

FIG. 8 is an explanatory view showing the structure of another main part of the image reading apparatus according to the present invention. In addition to the structure shown in FIG. 1, the transparent glass 8 is provided at the opening of the document guide 106.
01 is provided, and the conveying portion of the original 101 and the side of the white reference plate 103 have a closed structure. As a result, it is possible to prevent dust such as paper dust from entering the white reference plate 103 side, and it is possible to eliminate variations in the reading level of the white reference plate 101 over time.

FIG. 9 is an explanatory view showing the structure of another main part of the image reading apparatus according to the present invention. In addition to the structure shown in FIG. The brush 901 for removing the original guide 106 is brought into contact with the white reference plate 103 and the blackboard 104, respectively.
To be installed. As a result, the solenoid 108 is turned ON / O.
When the FF slides, the brush 901 rubs the surfaces of the white reference plate 103 and the blackboard 104, so that it is possible to remove adhered substances such as paper dust and dust. Therefore, since each reference surface is stable, variations in the reading level over time can be eliminated.

FIG. 10 and FIG. 11 are explanatory views showing the configuration of another main part of the image reading apparatus according to the present invention. In contrast to the configuration shown in FIG.
Only 04 is attached to the reference plate mounting member 102 in an overlapping manner, the original reading portion of the blackboard tension member 105 is opened, and the white reference plate 103 is fixed on the original reading portion.

The operation in the above configuration is the same as that shown in FIG. 1, and FIG.
FIG. 11 shows operating states when the size of the original 101 is detected. With this configuration, the weight of the reference plate mounting member 102 that moves for each sheet of the original 101 is reduced, so that the background portion of the original 101 can be switched more quickly, and the throughput can be further improved.
Further, the solenoid 108 can be downsized and power can be saved. Contrary to this example, the reference plate mounting member 10
The same effect can be obtained by attaching only the white reference plate 103 to 2 and fixing the blackboard 104.

FIG. 12 is an explanatory view showing the structure of another main part of the image reading apparatus according to the present invention. In addition to the structure shown in FIG. 11, the manuscript guide 106 is the same as that shown in FIG. A transparent glass 801 is provided at the opening of the
01 The transport portion and the white reference plate 103 side have a closed structure.
As a result, dust such as paper dust can be prevented from entering the white reference plate 103 side, and variations in the reading level of the white reference plate 103 over time can be eliminated.

FIG. 13 is an explanatory view showing the structure of another main part of the image reading apparatus according to the present invention. In addition to the structure shown in FIG. 11, a white reference plate similar to that shown in FIG. 1
A brush 901 for removing deposits on the 03 side is provided on the reference plate mounting member 102 so as to contact the white reference plate 103, and the brush 901 is attached to the document guide 106 so as to contact the blackboard 104 side. To be installed. This allows the white reference plate 103 and the blackboard 10 to be moved during the sliding operation by turning the solenoid 108 ON / OFF.
By rubbing the four surfaces with the brush 901, the attached matter can be removed. Therefore, since each reference surface is stable, variations in the reading level over time can be eliminated. For the brush 901, a flocked brush or a felt material is used.

[0039]

As described above, the image reading apparatus according to the present invention detects the white reference plate and the size of each original by moving means while the optical system is fixed during shading correction and original size detection. The plate is switched to the reading position to perform image reading, the cleaning member is placed in contact with each reference surface, the adhering material on the surface is removed as the moving means reciprocates, and Since a light-tight sealing member is provided on the original side of the moving means to prevent foreign matter from entering each reference surface, it is possible to perform shading correction and size detection for each original. Since the shading level can be stabilized over time and high-speed processing is possible, the reading efficiency and reading quality can be improved.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a schematic configuration of an ADF portion according to the present invention.

FIG. 3 is an explanatory diagram showing a relationship (a solenoid is in an OFF state) between an optical system and a white reference plate during shading correction according to the present invention.

FIG. 4 is an explanatory diagram showing a relationship between an optical system and a blackboard at the time of size detection according to the present invention (a solenoid is in an ON state).

FIG. 5 is a block diagram showing a schematic configuration of an image signal processing circuit according to the present invention.

FIG. 6 is a timing chart showing a first operation timing according to the present invention.

FIG. 7 is a timing chart showing a second operation timing according to the present invention.

FIG. 8 is an explanatory diagram showing another main part configuration of the image reading apparatus according to the present invention.

FIG. 9 is an explanatory diagram showing the configuration of another main part of the image reading apparatus according to the present invention.

FIG. 10 is an explanatory diagram showing another main configuration of the image reading apparatus according to the present invention.

11 is an explanatory diagram showing an operation state at the time of detecting the document size shown in FIG.

FIG. 12 is an explanatory diagram showing another main part configuration of the image reading apparatus according to the present invention.

FIG. 13 is an explanatory diagram showing the configuration of another main part of the image reading apparatus according to the present invention.

FIG. 14 is an explanatory diagram showing a main part configuration of a conventional image reading apparatus.

[Explanation of symbols]

103 White Reference Plate 104 Blackboard 105 Blackboard Tensile Member 108 Solenoid 801 Transparent Glass 901 Brush

Claims (8)

[Claims] 1. A white reference plate serving as a reference for shading correction, a size detection plate serving as a reference for document size detection, and a shading correction or document size detection process for the reading position of the white reference plate and the size detection plate. An image reading apparatus, comprising: a moving unit that moves each unit. 2. The image reading apparatus according to claim 1, wherein the document size detection is executed after a lapse of a predetermined time after the moving unit is turned on. 3. The image reading device according to claim 1, wherein in the shading correction, the correction data is read after the movement means starts the operation. 4. A white reference plate serving as a reference for shading correction, a size detection plate serving as a reference for document size detection, and the white reference plate and the size detection plate for each shading correction or document size detection with respect to a reading position. An image reading apparatus comprising: a moving unit for moving the moving unit to a position and a translucent sealing member arranged between the moving unit and a document placing portion. 5. A white reference plate serving as a shading correction reference, a size detecting plate serving as a document size detecting reference, and the white reference plate and the size detecting plate for each shading correction or document size detection with respect to a reading position. An image reading apparatus comprising: a moving unit for moving the reference plane of the white reference plate and the size detection plate to clean the reference plane. 6. A white reference plate as a reference for shading correction, a size detection plate as a reference for document size detection, and a moving means for moving the white reference plate or the size detection plate to a reading position. A white reference plate (size detection plate) is fixed at the reading position, and the size detection plate (white reference plate) is moved by the moving means for each shading correction or document size detection process with respect to the reading position. Image reading device. 7. A white reference plate serving as a reference for shading correction, a size detection plate serving as a reference for detecting an original size, moving means for moving the white reference plate or the size detecting plate to a reading position, and the moving means. A cleaning member that cleans the white reference plate or the size detection plate as it moves,
The white reference plate (size detection plate) is fixed to the reading position, and the size detection plate (white reference plate) is moved by the moving unit for each shading correction or document size detection process with respect to the reading position. Image reading device. 8. A white reference plate as a reference for shading correction, a size detection plate as a reference for original size detection, a moving means for moving the white reference plate or the size detection plate to a reading position, and the moving means. And a translucent sealing member disposed between the document placing portions, the white reference plate (size detection plate) is fixed at a reading position, and the size detection plate (white reference plate) is moved by the moving means. An image reading apparatus which moves with respect to a reading position for each shading correction or document size detection process.