JP2003060860A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader in which resolution in improved without increasing the number of pixels of a linear sensor. SOLUTION: Two lenses 29 and 30 are arrayed so that their optical axes O and P can be mutually parallel, and an original image on a main scanning line is almost bisected by these lenses 29 and 30 and formed being superimposed on a linear sensor 20. Further, a switching drum 60 is provided for selectively opening one of two optical paths from the surface of an original through the lenses 29 and 30 to the linear sensor 30 and closing the other optical path. In this switching drum 60, for example, one of optical paths is opened by opening the windows 70 and 71 and the other optical path is shut down by a light shading part 82 or 83 on the other hand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device.

[0002]

2. Description of the Related Art Conventionally, as a device for reading a document image, an image reading device such as an image scanner, a copying machine or a facsimile has been known. It is desired that these image reading devices have higher resolution.
The higher the resolution, the finer the original image can be read,
This is because it is possible to acquire a lot of information about the document image.

Some of the above-mentioned image reading devices are of a type in which an original image is formed on a linear sensor by using an optical system such as a lens and a mirror. The resolution in the main scanning direction of such an image reading device is determined by the number of pixels of the linear sensor. As a method of increasing the number of pixels, there is a method of reducing the size of one pixel without changing the length of the linear sensor in the main scanning direction and a method of lengthening the linear sensor in the main scanning direction without changing the pixel size. Known from the past.

[0004]

However, when the pixel size is reduced and the number of pixels is increased, the sensitivity of each pixel is lowered, and since the electric charge accumulated in each photoelectric conversion element is small, the linear sensor The influence of noise on the output signal becomes a problem.

Further, it is difficult to fabricate a linear sensor long in the main scanning direction in one chip due to restrictions such as the size of the wafer. However, it is also possible to lengthen the length in a pseudo manner by arranging a plurality of linear sensors in the main scanning direction,
It is difficult to arrange multiple linear sensors so that the entire continuous area in the main scanning direction can be read without omission.
This causes an increase in manufacturing cost.

When the number of pixels of the linear sensor is constant, the magnification of the optical system and the reading width in the main scanning direction are in inverse proportion. That is, when the magnification of the optical system is increased without changing the number of pixels of the linear sensor, the maximum width of the original image on the main scanning line that the optical system can form on the linear sensor is narrowed.

The present invention was created in view of such circumstances, and an object thereof is to provide an image reading apparatus for reading a large original image with high resolution without increasing the number of pixels of the linear sensor. Especially.

[0008]

According to the first aspect of the invention, the linear sensor outputs an image signal according to the density of the optical image by photoelectric conversion, and the plurality of lenses are arranged with their optical axes parallel to each other. The original image on the scanning line is superposed on the linear sensor to form an image, and the main scanning drive section selects and opens one of a plurality of optical paths from the original surface to the linear sensor through the lens. The sub-scanning drive unit moves the main scanning line in a direction perpendicular to the main scanning line, the processing unit processes the output signal of the linear sensor, and the control unit controls the linear sensor and the main scanning driving unit. Controlling the sub-scan drive unit and the processing unit.

According to the first aspect of the present invention, the lenses arranged so that their optical axes are parallel to each other form regions, which are regions of a part of the original image on the main scanning line and are different from each other, on the linear sensor. Therefore, by appropriately setting the lens arrangement, the main scanning line can be set to be long and a large original image can be read, and the magnification of the lens can be arbitrarily set according to the number of arranged lenses. Moreover, since each lens forms a narrow area, which is a part of the original image on the main scanning line, on the linear sensor, the original image in the area can be read with high resolution. In the present specification, the main scanning line is a scanning line for pixels of one row forming an image.

Further, according to the first aspect of the present invention, the main scanning drive section selects and opens one of the plurality of optical paths while blocking the other optical paths, so that each lens linearly scans the original image at different times. Form an image on the sensor. Further, the respective lenses arranged as described above form an original image at the same magnification without distortion. Therefore, by generating and synthesizing the image data representing the light and shade information of the original image formed by each lens on the linear sensor by the processing unit, the image data accurately representing the light and shade information of the entire original image can be obtained. .

From the above, according to the invention of claim 1,
It is possible to provide an image reading device that reads a large original image with high resolution without increasing the number of pixels of the linear sensor.

According to the invention of claim 2, the original images formed by the lenses adjacent to each other on the linear sensor partially overlap each other. Therefore, for example, when synthesizing the image data obtained as described above for each image formed by each lens on the linear sensor, the synthesizing accuracy can be improved by utilizing the overlapping portion.

According to a third aspect of the present invention, the control section causes the linear sensor and the main scanning drive section to alternately scan the entire original image on the main scanning line and move the main scanning line. Since the sub-scanning drive unit is controlled, the main scanning line can be read at least once over the entire length of the original image in the direction perpendicular to the main scanning line. .

According to a fourth aspect of the present invention, the control unit causes the main scanning drive unit to switch the selection of the optical path and the sub-scanning drive unit to move the main scanning line alternately. Since the scan driving unit and the sub-scanning driving unit are controlled, the number of times the main scanning driving unit switches the optical path selection is reduced. Therefore, according to the invention of claim 3, the time required for reading the original image can be shortened.

According to a fifth aspect of the present invention, the main scanning drive section has a plurality of light blocking members and a drive section connected in the arrangement direction of the plurality of lenses, and the drive section has the plurality of lenses. By rotating the light shielding member about a rotation axis parallel to the arrangement direction axis, the plurality of light shielding members are moved in and out of the optical path with a predetermined phase difference. Therefore, for example, according to the rotation of the plurality of light shielding members, while the one light shielding member is caused to retreat from the one light path, while the phase difference is set so that the other light shielding member is allowed to enter the other light path, the main scanning drive unit is set. It can be realized with a simple structure.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment showing an embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows an image scanner 1 as an image reading apparatus according to an embodiment of the present invention.
0 is shown. The image scanner 10 includes a linear sensor 20, lenses 29 and 30 that form an original image on the linear sensor 20, a carriage 24 that carries the linear sensor 20 and the lenses 29 and 30, a linear sensor drive circuit 102 that drives the linear sensor 20, A processing unit 100 that processes the output signal of the linear sensor 20, a control unit 110, and the like are provided.

Hereinafter, a so-called flat bed type image scanner 10 in which a document table 14 is provided on an upper surface of a casing 12 having a generally box shape as shown in FIG. 4 will be mainly described. The document table 14 is formed of a transparent plate such as a glass plate, and the document is placed on the plate surface. At the periphery of the document table 14, the document table 14
A document guide 16 for positioning the document is provided on the board surface.

The carriage 24 is provided in the housing 12,
The linear sensor 20 and the lenses 29 and 30 are conveyed parallel to the platen surface of the document table 14. This carriage 24
The carriage frame 25 has a generally rectangular dish shape, and the carriage cover 26 covers the opening of the carriage frame 25, and has a space inside. The carriage 24 is slidably locked to a shaft or the like, and can reciprocate in the sub-scanning direction (direction a in FIG. 4) parallel to the plate surface of the document table 14 with the carriage cover 26 facing the document table 14. Is. The carriage 24 is reciprocated by a carriage driving device 27 (see FIG. 3). The carriage driving device 27 includes, for example, a belt locked to the carriage 24 and a driving source such as a stepping motor that easily controls the rotation of the belt. A white reference 50 for a reflective original having a high-reflectance uniform reflecting surface is provided at one edge of the original table 14 in the sub-scanning direction so as to extend parallel to the main scanning direction axis.

As shown in FIG. 1, the linear sensor 20 is
A plurality of photoelectric conversion elements are arranged in the carriage 24 in a posture in which they are arranged linearly in a direction perpendicular to the movement direction axis of the carriage 24 (direction b in the figure) and parallel to the surface of the document table 14. An example of the photoelectric conversion element is a photodiode. The arrangement direction of the photoelectric conversion elements of the linear sensor 20 is the main scanning direction, and the moving direction of the carriage 24 is the sub scanning direction. As the linear sensor 20, visible light, infrared light,
The electric charge obtained by photoelectrically converting light of a predetermined wavelength range such as ultraviolet light is accumulated for a certain period of time, and an electric signal according to the amount of received light is CC
A lens reduction type linear image sensor that outputs using a D (Charge Coupled Device), a MOS transistor switch, or the like is used.

An on-chip color output system is adopted, and a 3-line or 6-line linear sensor 20 in which a color filter array is formed on-chip in the light receiving portion is used. The linear sensor 20 outputs an electric signal according to the arrangement state of the color filter array. As a color filter array, for example, R for each line
(Red), G (Green), or B (Blue) primary color filter is used. In addition, C (Cyan), M (Magent
a), Y (Yellow) and G (Green) 4 colors or CMY3
A color filter array may be configured by complementary color filters, or filters of a plurality of colors may be arranged in one line. As the color output system, any of a dichroic mirror system, a light source switching system, and a filter switching system may be adopted in addition to the above-described on-chip system.
Further, the present invention can naturally be applied to a monochrome output image reading device.

The linear sensor (CCD linear image sensor) 20 will be described in detail. The linear sensor 20 has a photoelectric conversion element, a shift gate, an analog shift register, and a charge-voltage converter, and operates as follows. (1) When light is received by each photoelectric conversion element, charges are accumulated in each photoelectric conversion element by photoelectric conversion. (2) The shift pulse is input to the shift gate by the linear sensor drive circuit 102, which will be described later, so that the charges accumulated in the photoelectric conversion element are transferred to the analog shift register. This charge transfer is carried out simultaneously for all photoelectric conversion elements. The time for accumulating charges in the photoelectric conversion element can be changed by changing the pulse interval of the shift pulse or using an electronic shutter. (3) Based on the input of the transfer pulse to the analog shift register by the linear sensor drive circuit 102, the charges transferred to the analog shift register are transferred to the charge-voltage converter. (4) The charges transferred to the charge-voltage converter are converted into voltage signals.

The linear sensor drive circuit 102 generates drive pulses such as shift pulses and transfer pulses necessary for driving the linear sensor 20 and outputs them to the linear sensor 20. The linear sensor drive circuit 102 includes, for example, a synchronization signal generator, a drive timing generator, and the like.

The lenses 29 and 30 have the same optical properties. As shown in FIG. 1, the lenses 29 and 30 are arranged in the carriage 24 in such a posture that their optical axes O and P are parallel to each other. The lenses 29 and 30 are provided at positions which are line-symmetrical to each other with the vertical bisector V of the linear sensor 20 as the axis of symmetry, and are arranged in a direction parallel to the main scanning direction axis.

As shown in FIG. 4, a reflective original light source 35 and a plurality of mirrors 31, are provided inside the carriage 24.
32, 33, 34 are provided. Light source for reflective original 3
Reference numeral 5 (hereinafter, also simply referred to as “light source 35”) is composed of tube illumination such as a fluorescent tube lamp, and is attached to the carriage cover 26 in an attitude extending in the main scanning direction. As shown by the broken lines in FIGS. 1, 2 and 4, the reflected light image of the reflected original on the original table 14 illuminated by the light source 35 passes through the slit 42 provided in the carriage cover 26 and the plurality of mirrors 31. , 32, 33, 34, and then the lens 2
An image is formed on the linear sensor 20 by each of 9 and 30.
Thus, when reading the reflection original, the mirrors 31, 3 are
2, 33, 34 and lenses 29, 30 etc.
The optical system 39 forms a first optical path passing through the lens 29 and a second optical path passing through the lens 30. Mirror 3
Reference numerals 1, 32, 33 and 34 are for increasing the optical path length from the document to the lens 30.

As shown by a chain double-dashed line in FIGS. 3 and 4, a transparent original surface light source 40 (hereinafter also simply referred to as “surface light source 40”) is detachably provided in the housing 12. The surface light source 40 is mounted above the document table 14 when reading a transparent original, and is removed when reading a reflective original. The surface light source 40 in the present embodiment is composed of a tube illumination such as a fluorescent tube lamp (not shown) and a reflection plate and a diffusion plate (not shown), and the irradiation light of the tube illumination is transmitted to the transparent original on the original table 14 by the diffusion plate. Irradiation is almost uniform. The transmitted light image of the transparent original on the original table 14 illuminated by the surface light source 40 is the same as the case of the reflected light image.
An image is formed on the linear sensor 20 through two optical paths by an optical system including 2, 33, 34 and lenses 29, 30.

When reading any type of original with the image scanner 10, the lens 29 is, as shown in FIG. 1, a first portion (in FIG. 1) of the original image on the main scanning line extending from substantially the center to one end. The portion (A) is imaged on the entire width of the linear sensor 20. On the other hand, as shown in FIG. 2, the lens 30 forms a second portion (portion B in the same figure) of the original image on the main scanning line extending from the substantially center to the other end on the entire width of the linear sensor 20. That is, the first portion and the second portion are formed by the lenses 29 and 30 and the linear sensor 20.
Is superimposed and imaged. As described above, the lenses 29, 3
0 has the same optical properties and is arranged side by side in the direction parallel to the main scanning direction axis with the optical axes O and P parallel to each other, so that the first portion and the second portion are the same. An image is formed on the linear sensor 20 without distortion due to magnification. In this embodiment, the angle of view of the lens 30 is set to a predetermined value, as shown in FIG.
As shown in the enlarged view, the first portion and the second portion overlap by a predetermined width.

As shown in FIG. 1, a switching drum 60 is further mounted inside the carriage 24. The switching drum 60 is provided to select one of the two optical paths, open the same, and block the other.

Specifically, the switching drum 60 includes a drum body 62 having a generally cylindrical shape and the drum body 6 thereof.
The rotary shafts 63 and 64 extend outwardly in the direction of the cylinder axis from both ends of the shaft 2. The rotary shafts 63 and 64 are supported by rolling bearings 65 and 66 fixed to the carriage 24, respectively. With the drum body 62 facing the two lenses 29, 30 and the linear sensor 20,
It is rotatable about a rotation axis (cylindrical axis) Q extending parallel to the main scanning direction axis.

The outer peripheral surface of the drum body 62 is divided into a first area 67 on the lens 29 side and a second area 68 on the lens 30 side with a plane S bisecting the linear sensor 20 in between. There is. As shown in FIG. 1 and FIG. 6A, in the first region 67, two opening windows 70 penetrating the cylindrical wall,
71 is formed at a position facing each other across the rotation axis Q, and light-shielding portions 80 and 81 are formed at the portions sandwiched by the opening windows 70 and 71 in the circumferential direction. Meanwhile, FIG. 2 and FIG.
As shown in (b), the opening window 7 is formed in the second area 68.
Two opening windows 72 and 73 similar to 0 and 71 are the rotation axis Q.
Light-shielding portions 82 and 83 are formed so as to face each other with the opening windows sandwiched therebetween, and are sandwiched by the opening windows 72 and 73 in the circumferential direction. The direction in which the opening windows 70, 71 face each other is
The opening windows 72, 73 are deviated by 90 degrees around the rotation axis Q with respect to the direction in which they face each other. The opening windows 70, 71 in the first area 67 and the opening windows 72, 73 in the second area 68 are not adjacent to each other in the rotation axis direction. In the present embodiment, a part of the opening windows 70, 71 in the first area 67 and a part of the opening windows 72, 73 in the second area 68 respectively correspond to the light shielding portions 82, 83 in the second area 68 and the first opening. It penetrates into the light shielding portions 80 and 81 in the area 67.

The switching drum 60 (drum body 62) is intermittently rotated by the drum driving device 90 between the first rotation position and the second rotation position with a phase difference of 90 degrees about the rotation axis Q. The drum drive device 90 includes a drive source such as a stepping motor that is easy to control. For example, as shown in FIG. 1, the first rotation position (hereinafter, also simply referred to as “first position”) opens the first optical path with the opening windows 70 and 71 and blocks the second optical path with the light shielding portion 82 or 83. The position. The second rotation position (hereinafter, also simply referred to as “second position”) is, for example, as shown in FIG. 2, the opening windows 72 and 73.
Is the position where the second optical path is opened and the first light path is blocked by the light shielding portion 80 or 81. As described above, in the present embodiment, the light shielding portion 80,
The selection of the optical path is switched by causing 81 and the light shielding portions 82 and 83 to enter each optical path with a phase difference of 90 degrees. Although the switching drum 60 is provided between the lenses 29 and 30 on the two optical paths and the linear sensor 20 in this embodiment,
It may be provided between the original and the lenses 29 and 30.

As shown in FIG. 3, the processing section 100 comprises an analog signal processing circuit 104, an A / D converter 106 and a digital signal processing circuit 108. In this embodiment, the analog signal processing circuit 10 of the processing unit 100 is used.
4 and the A / D converter 106 are the linear sensor drive circuit 10
The digital signal processing circuit 108 is mounted on the carriage 24 together with the control unit 110. The circuit mounted on the carriage 24 and the circuit fixed to the housing 12 are connected by a flexible flat cable (not shown).

The analog signal processing circuit 104 performs analog signal processing such as amplification and noise reduction processing on the analog electric signal output from the linear sensor 20, and outputs the processed signal to the A / D converter 106. Output. Amplification in the analog signal processing is performed by, for example, a preamplifier or an auto gain control circuit. The noise reduction process is performed using, for example, the correlated double sampling method. The analog signal processing circuit 104 can further perform a white clipping process of limiting a signal amplitude and clipping a white level for an excessively large input signal.

The A / D converter 106 quantizes the analog electric signal output from the analog signal processing circuit 104 into a digital image signal of a predetermined gradation, and outputs the image signal to the digital signal processing circuit 108.

The digital signal processing circuit 108 is an A / D
Various processes are performed on the image signal output from the converter 106. Specifically, the digital signal processing circuit 108
Is a shading correction unit 120 and a gamma correction unit 122.
And a defective pixel correction unit 124.

The shading correction unit 120 corrects shading due to variations in sensitivity of each pixel of the linear sensor 20 or each block of several pixels, and an irradiation light amount distribution in the main scanning direction of the light source 35 or the surface light source 40. . This shading correction is performed by reading the white reference 50 for the reflective original at each rotational position of the switching drum 60 prior to the reading of the original or by making the irradiation light of the surface light source 40 incident on the linear sensor 20 without transmitting the transparent original. Using the white reference data obtained by the above, or the white reference data and the memory (for example, the ROM 13
4) using the black reference data stored in advance.

The gamma correction unit 122 performs gamma correction on the image signal according to the gamma characteristic of the image processing apparatus 150 connected to the image scanner 10. This gamma correction is performed by a look-up table method, for example. The look-up table method uses a memory (for example, RO
In M134), the data written in the address corresponding to the input level of the image signal is searched and read as an output signal.

The defective pixel correction section 124 is a unit for interpolating a signal of a defective pixel with a signal of an adjacent pixel by a pixel interpolation method to generate the signal.

In the digital signal processing circuit 108, in addition to the above-described corrections, for example, pixel number conversion processing, color correction for faithfully reproducing the color of the original image, and high-frequency components of the image signal are emphasized and sharpened. It is possible to perform MTF correction for this purpose, white clip processing using a multiplexer, and the like. The digital signal processing circuit 108 can further perform standardization processing, binarization processing, dither processing for reproducing halftones, and the like depending on the type of the image processing apparatus 150. It should be noted that the various types of processing performed by the digital signal processing circuit 108 can be replaced with processing by a computer program executed by the control unit 110 or the image processing apparatus 150.

In the present embodiment, the digital signal processing circuit 108 scans the first or second portion of the original image on the main scanning line with the linear sensor 20 while the switching drum 60 is held at the first or second position. Each time the A / D converter 106 outputs a signal that correlates to the shade of the first or second portion, the above-described various processes are executed to generate the first or second main scanning data. That is, as shown in FIG. 8, the obtained first main scanning data and second main scanning data represent the shading of the first portion or the second portion of the original image on one main scanning line. The digital signal processing circuit 108 can output the obtained main scan data after connecting them to each other or without connecting them. For example, the first main scanning data and the second main scanning data can be connected and output by providing the digital signal processing circuit 108 with the following main scanning data combining unit 126. Specifically, as shown in FIG. 8, the control unit 110 detects pixels (boundary pixels) at which the lenses 29 and 30 form black dots provided as a reference, at the time of manufacturing or before the reading operation of each document, and the same pixel is detected. The first main scanning data and the second main scanning data obtained for the main scanning line are combined by the main scanning data combining unit 126 at each boundary pixel and combined. Up to this point, the A / D converter 1
06 output signal to the digital signal processing circuit 108
It is described that after performing various processes such as correction to generate the first main scanning data and the second main scanning data, the corrected first main scanning data and the second main scanning data are connected. In the digital signal processing circuit 108
The first main scanning data and the second main scanning data are concatenated and combined at the pre-stage or the mid-stage of each process for the output signal of the D / D converter 106, and the obtained image data is subjected to the remaining correction process to form an image. It may be transferred to the processing device 150.

As shown in FIG. 3, the control unit 110 is a CPU.
It has 130, RAM 132, and ROM 134.
The CPU 130 controls the drive of the linear sensor 20 (that is, the operation control of the linear sensor drive circuit 102) and the movement of the carriage 24 (that is, the carriage drive device 27).
Control of the switching drum 60 (that is, the driving of the drum driving device 90), the blinking operation of the light source 35 for the reflective original and the surface light source 40 for the transparent original, the control of the light amount, the operational control of the processing unit 100, etc. Image scanner 1
Controls the entire 0. The RAM 132 temporarily stores main scanning data generated by the digital signal processing circuit 108, image signals being processed by the digital signal processing circuit 108, and the like. The ROM 134 stores various computer programs for the CPU 130 to control each unit of the image scanner 10.

The control section 110 is connectable to an image processing apparatus 150 such as a personal computer via an interface (I / F) 140 provided on the housing 12. The control unit 110, based on the read command signal from the image processing apparatus 150 connected thereto, controls the ROM 1
Of the computer programs stored in 34, those relating to the reading of the original document are executed. As a result, the original is read and the data output from the digital signal processing circuit 108 is transferred to the image processing device 15 through the I / F 140.
Is transferred to 0.

The configuration of the image scanner 10 has been described above. The operation of the image scanner 10 will be described below.
In the description below, the image scanner 10 is a personal computer (PC) as the image processing apparatus 150.
Be connected to.

The user of the image scanner 10 places an original on the original table 14 and then instructs the image scanner 10 to read the original by an input operation to the PC 150. In response to the command, the image scanner 10 operates as follows.

First, the operation when the carriage 24 is moved only once in the sub-scanning direction to scan the entire portion of the original image will be described with reference to FIGS. 7 (a) and 7 (b). (1) First, the carriage 24 is moved in a state where the switching drum 60 is rotated to the first position, and the linear sensor 20 is caused to scan an area A of approximately half of the main scanning line at a predetermined position in the sub scanning direction. Next, the switching drum 60 is rotated to the second position, and the linear sensor 20 is caused to scan the remaining area B of the same main scanning line as the previous time at the same position in the sub scanning direction as the previous time. At this time, it suffices that the position in the sub-scanning direction scanned by the linear sensor 20 is substantially the same as the previous position, and the position may be deviated by a slight distance in the sub-scanning direction. That is, it is not always necessary to stop the carriage 24 during main scanning, and the width of the main scanning line in the sub scanning direction may be larger than the width of one pixel. (2) Next, the main scanning line is moved in the sub-scanning direction by moving the carriage 24. Then, the switching drum 6
In the state where 0 is held at the second position or when it is rotated to the first position, the linear sensor 20 has an area B which is approximately half of the main scanning line at a position away from the previous time by a predetermined distance in the sub-scanning direction (FIG. 7A).
Or in the area A (in the case of FIG. 7B). When the area B on the same main scanning direction side as the previous area is scanned without rotating the switching drum 60, the movement of the carriage 24 and the rotating operation of the switching drum 60 are alternately performed, and the rotation of the switching drum 60 is performed. Since the number of operations is reduced by half, the time required for reading can be shortened. Then, the switching drum 60 is rotated to a rotation position different from the previous rotation position, and the linear sensor 20 is caused to scan the remaining area A or B of the same main scanning line as the previous time at the same position in the sub scanning direction as the previous time. (3) The above steps (1) and (2) are repeated until the main scanning line reaches the moving end in the sub-scanning direction. As described above, in the present embodiment, the switching drum 60 is used to switch the optical path at high speed, so that the entire original image can be scanned at high speed. (4) Each area A, B of one main scanning line is processed by the processing unit 100.
Each time the scanning is performed, the output signal from the linear sensor 20 is processed, and each time the first main scanning data and the second main scanning data are generated for the same main scanning line, the digital signal processing circuit 108 outputs the first and second main scanning data. The two main scan data are concatenated and combined, and the combined image data is connected to the PC1.
Transfer to 50. The image data for each main scanning line transferred to the PC 150 are connected to each other by the processing of the PC 150, and as a result, image data representing the optical density information of the entire original image is acquired. The A / D converter 10
The digital signal processing circuit 108 performs various processes such as correction on the output signal of 6 to generate the first main scanning data and the second main scanning data, which are then individually transferred to the PC 150, and the PC 150 performs each main scanning. You may make it synthesize | combine data.

Next, the operation when the carriage 24 is moved twice in the sub-scanning direction to scan the entire portion of the original image will be described with reference to FIG. (1) First, the carriage 24 is moved in a state where the switching drum 60 is rotated to the first position, and the linear sensor 20 is caused to scan an area A of approximately half of the main scanning line at a predetermined position in the sub scanning direction. Next, while the switching drum 60 is held at the first position, the carriage 24 is moved to move the main scanning line in the sub-scanning direction, and then the linear sensor 20 is moved to a position separated from the previous position by a predetermined distance in the sub-scanning direction. The area A, which is almost half of the main scanning line, is scanned. The above is repeated until the main scanning line reaches the moving end in the sub scanning direction. (2) Next, rotate the switching drum 60 to the second position,
The linear sensor 20 is caused to scan the remaining area B of the same main scanning line as the previous time at the same position in the sub-scanning direction as the previous time. Subsequently, with the switching drum 60 held at the second position, the carriage 24 is moved to move the main scanning line in the sub-scanning direction, and then the linear sensor 20 is moved to a position away from the previous time by a predetermined distance in the sub-scanning direction. The area B, which is almost half of the main scanning line of the above, and is on the main scanning direction side same as the previous area is scanned.
The above is repeated until the main scanning line reaches the moving end in the sub scanning direction. (3) By the processing unit 100, the areas A and B of one main scanning line
Every time is scanned, the output signal from the linear sensor 20 is processed to generate the first main scanning data or the second main scanning data, which is transferred to the PC 150. The respective main scan data transferred to the PC 150 are processed by the PC 150 to compare a predetermined number (for example, 100 pixels) of pixel information from both ends, detect an overlapped imaged area, and combine them. Image data representing information is generated.

In the image scanner 10 described above,
Since each lens 29, 30 forms a narrow area of almost half of the original image on the main scanning line on the linear sensor 20, the original image in the area can be read with high resolution. Further, the first and second main scanning data obtained by the digital signal processing circuit 108 are transmitted to the linear sensor 20 by the lenses 29 and 30 at the same magnification without distortion of the first portion or the second portion of the original image on one main scanning line. The image data represents the formed image. Therefore, the image data obtained by synthesizing the respective main scanning data accurately represents the grayscale information of the entire original image.

As is apparent from the above description, in the present embodiment, the drum drive device 90 and the switching drum 60 constitute an example of the "main scanning drive section" described in the claims, and each light shield is provided. The parts 80, 81, 82, and 83 configure an example of the “light-shielding member” described in the claims, and the drum driving device 90 configures an example of the “drive unit” described in the claims, and drive the carriage. The device 27 and the carriage 24 constitute an example of a "sub-scanning drive unit" described in the claims, and the processing unit 100 is a "processing unit" described in the claims.
That is, the control unit 110 constitutes an example of the “control unit” described in the claims.

Although one embodiment of the present invention has been described in detail above, this is merely an example, and the present invention should not be construed as being limited by the description of such an embodiment.

For example, in the above embodiment, two lenses 2
9 and 30 are arranged so that the optical axes O and P are parallel to each other, and the original image on the main scanning line is almost divided into two to form a linear sensor 20.
However, three or more lenses may be arranged so that their optical axes are parallel to each other, and the original image may be further finely divided to form an image on the linear sensor 20. In this case, it is desirable to set the angle of view of the lens so that the divided areas overlap each other, as in the above-described embodiment. Note that FIG. 9 shows three lenses 4
An example is shown in which 00, 402, 404 are arrayed and the original image on the main scanning line is divided into approximately three and formed on the linear sensor 20.

Further, in the above-described embodiment, in order to switch the selection of the optical paths, the light-shielding portions 80 and 81 and the light-shielding portions 82 and 83 formed on the drum body 62 having a generally cylindrical shape have a phase difference of 90 degrees with each optical path. Although the switching drum 60 that is inserted into the optical path switching member 60 is used, the optical path switching member 300 shown in FIG. 10 may be used instead of such a switching drum 60. This optical path switching member 300 serves as a light blocking member.
It has two light blocking plates 304 and 306. Those shading plates 30
4, 306 are connected to each other side by side in the direction of the rotation axis R via the rotation axis 302, and spread in the plane directions of two imaginary planes orthogonal to each other with the rotation axis R as a line of intersection. The optical path switching member 300 is intermittently rotated by 90 degrees about a rotation axis R by a driving device (not shown) as a driving source, and the light shielding plates 304, 3 are rotated according to the rotation position.
06 is made to enter each optical path with a phase difference of 90 degrees. In addition, the switching drum 60 and the optical path switching member 300.
In both cases, when three or more optical paths are formed by arranging three or more lenses, a light shielding part or a light shielding plate is added in the rotation axis direction according to the number of the optical paths. In addition to the above-described switching drum 60 and the optical path switching member 300 that utilize the rotational movement of the light blocking member, for example, there are a plurality of opening windows that open a plurality of optical paths and are arranged in the arrangement direction of the plurality of lenses. The main scanning drive unit described in the claims may be configured by an optical path switching mechanism including an optical path switching mechanism that includes a shutter member that selectively blocks the plurality of opening windows to block the optical path.

Furthermore, in the above-mentioned embodiment, the case where the present invention is applied to the flatbed type image scanner has been described. However, the present invention is not limited to the flatbed type image reading device but also to the sheet feed type image reading device. Applicable. When the present invention is applied to a sheet feed type image reading apparatus, an auto sheet feeder can be used as an example of the sub-scanning driving unit described in the claims.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining how an original image on a main scanning line is formed on a linear sensor by one of two lenses in an image scanner according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining how an original image on a main scanning line is formed on a linear sensor by the other of two lenses in an image scanner according to an embodiment of the present invention.

FIG. 3 is a block diagram showing an image scanner according to an exemplary embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of an image scanner according to an exemplary embodiment of the present invention.

FIG. 5 is a schematic view showing a state in which original images formed by the lenses on the linear sensor partially overlap in the image scanner according to the embodiment of the present invention, and FIGS.
It is equivalent to the enlarged view of the C section in FIG.

FIG. 6 is a cross-sectional view showing a switching drum provided in the image scanner according to the embodiment of the present invention, FIG.
1 corresponds to the α-α sectional view of FIG. 1, and (b) corresponds to the β-β sectional view of FIG. 1.

FIG. 7 is a schematic view for explaining a method of scanning the entire portion of the original image in the image scanner according to the embodiment of the present invention, and FIGS. 7A and 7B are diagrams showing the carriage 24 in the sub-scanning direction. In the case of moving the carriage 24 only once, (c) shows the case of moving the carriage 24 twice in the sub-scanning direction.

FIG. 8 is a schematic diagram for explaining a method of linking and combining first main scanning data and second main scanning data acquired for the same main scanning line in the image scanner according to the embodiment of the present invention. .

FIG. 9 is a schematic diagram showing an example in which, unlike the image scanner according to the embodiment of the present invention, three lenses are arranged and a document image on a main scanning line is substantially divided into three and formed on a linear sensor.

FIG. 10 is a schematic view showing an optical path switching member that can be used instead of the switching drum of the image scanner according to the embodiment of the present invention, FIG.
Is a sectional side view.

[Explanation of symbols]

10 image scanner 20 linear sensor 24 carriage 27 Carriage drive 29, 30, 400, 402, 404 Lens 60 switching drum 70,71,72,73 Opening window 80, 81, 82, 83 Light-shielding part 90 drum drive 100 processing unit 102 Linear sensor drive circuit 110 control unit 300 Optical path switching member 304,306 Light shield A first part (area) B Second part (area) O, P optical axis Q, R rotation axis

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/028 H04N 1/04 102 F term (reference) 5B047 AA01 BA02 BB02 BC01 BC05 BC15 CA05 CA07 CA11 CA14 CA17 CB17 5C051 AA01 BA03 DA03 DB01 DB07 DB22 DB24 DB28 DC03 DC04 DC07 DE02 DE09 FA01 5C072 AA01 BA16 DA03 DA15 DA21 EA05 FB02 FB03 FB27 MB08 RA06

Claims (5)

[Claims] 1. A linear sensor that outputs an image signal according to the light and shade of an optical image by photoelectric conversion, and an original image on a main scanning line, which is arranged with their optical axes parallel to each other, is superimposed and formed on the linear sensor. A plurality of lenses, a main scanning drive unit that selects one of a plurality of optical paths from the document surface to the linear sensor through the lens to open it and block the other, and a main scanning line perpendicular to the main scanning line A sub-scanning driving unit that moves in any direction, a processing unit that processes the output signal of the linear sensor, a control unit that controls the linear sensor, the main scanning driving unit, the sub-scanning driving unit, and the processing unit, An image reading apparatus comprising: 2. The image reading apparatus according to claim 1, wherein the original images formed by the lenses adjacent to each other on the linear sensor partially overlap each other. 3. The control unit controls the linear sensor, the main scanning drive unit, and the sub-scanning drive unit so that scanning of the entire original image on the main scanning line and movement of the main scanning line are performed alternately. The image reading apparatus according to claim 1, which is controlled. 4. The main scanning drive unit and the sub-scanning unit so that the switching of the optical path selection by the main scanning drive unit and the movement of the main scanning line by the sub-scanning drive unit are alternately performed by the control unit. The image reading apparatus according to claim 3, wherein the driving unit is controlled. 5. The main scanning drive unit includes a plurality of light-shielding members connected in the arrangement direction of the plurality of lenses, and the light-shielding member around a rotation axis parallel to an arrangement direction axis of the plurality of lenses. 5. The image reading apparatus according to claim 1, further comprising a drive unit that rotates each of the plurality of light blocking members into and out of the optical path with a predetermined phase difference.