JP2005260684A - Contact image sensor module and image reading apparatus provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus provided with a contact image sensor module reading an image with high image quality at a fast reading speed. <P>SOLUTION: The image reading apparatus is provided with: the contact image sensor module including: a first light source section for emitting a plurality of colors of light subjected to time division; a second light source section for emitting white light to illuminate a second object; a first image sensor wherein a first light receiving element group of one channel is linearly arranged; a second image sensor wherein second light receiving element groups of 3 channels are arranged in parallel with the first light receiving element group, and whose resolution differs from that of the first image sensor; a first lens section for forming an image of a first object to the first light receiving element group; a second lens section for forming an image of a second object to the second light receiving element groups; and a color filter for separating colors of the white light emitted from the second light source and making the separated colors incident onto each channel of the second light receiving element group. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus including a contact image sensor module.

2. Description of the Related Art Conventionally, an image reading apparatus (see Patent Document 1) on which a contact image sensor module is mounted is known. Since the contact image sensor module has a short optical path of the optical system, the image reading apparatus can be easily downsized.
However, the contact image sensor module includes an image sensor having a length corresponding to the maximum reading width of a document. Therefore, for example, in an image reading apparatus having an A4 size width of the maximum reading width, it is necessary to increase the resolution of an A4 size width image sensor even in order to increase the reading resolution of a 35 mm film. In general, as the resolution of an image sensor increases, noise generated by the image sensor increases. Therefore, in the image reading apparatus described in Patent Document 1, when the resolution of the image sensor is increased in accordance with an original having a small original size such as a 35 mm film and a high recording density of image information, the image information is recorded like a printed document. There is a problem that the image quality of a read image of a document having a relatively low density is lowered in all document sizes.
In addition, the contact image sensor module includes an LED that emits red light, an LED that emits green light, and an LED that emits blue light. I do. For this reason, the image reading apparatus described in Patent Document 1 has a problem that reading speed is low.

The image reading apparatuses described in Patent Documents 2 and 3 include a plurality of optical systems, and can read an original with a desired resolution by changing an optical path according to the original. However, the image reading apparatuses described in Patent Documents 2 and 3 have a problem that the configuration of the optical system is complicated and the optical path is long, so that the manufacturing cost is high and it is not suitable for downsizing.
JP 2001-133906 A JP 2003-37712 A JP 2003-37713 A

  The present invention has been made in view of the above problems, and an object thereof is to provide an image reading apparatus including a contact image sensor module that has a high reading speed and can read a high-quality image. .

In order to achieve the above object, an image reading apparatus according to the present invention radiates a plurality of colors of light in a time-division manner, illuminates a first object, emits white light, and produces a second object. A second light source unit for illuminating an object, a first image sensor in which a first light receiving element group of one channel is arranged linearly, and a second light receiving element group of three channels are arranged in parallel with the first light receiving element group A second image sensor having a resolution different from that of the first image sensor, a first lens unit that forms an image of the first object on the first light receiving element group, and a second object connected to the second light receiving element group. A contact-type image sensor module having a second lens unit for imaging, and a color filter for separating white light emitted from the second light source unit and causing the white light to enter each channel of the second light receiving element group. . In general, as the resolution of an image sensor increases, noise generated by the image sensor increases. In the contact image sensor module according to the present invention, since the resolution of the first image sensor and the resolution of the second image sensor are different, an image sensor having a resolution suitable for the reading resolution can be used. By using a low-resolution image sensor in the low-resolution reading process, it is possible to reduce the occurrence of the above-described noise, so that the image quality of an image read at a low resolution can be improved.
In addition, the first image sensor converts an optical image of the first object into an electric signal by light emitted by the first light source unit in a time-sharing manner. Therefore, the reading time by the first image sensor is longer than the reading time by the second image sensor. By reading an image with a large number of pixels read by the second image sensor, the reading time can be shortened.

  Further, in the image processing apparatus according to the present invention, the width in the longitudinal direction of the arrangement range of the first light receiving element group is different from the width in the longitudinal direction of the arrangement range of the second light receiving element group. The first image sensor or the second image can be obtained by shortening the width in the longitudinal direction of the arrangement range of the light receiving element group arranged in the image sensor that requires reading with a high resolution and reads a small-sized document according to the document. The manufacturing cost of the sensor can be reduced. That is, the manufacturing cost of the contact image sensor module according to the present invention can be reduced.

Hereinafter, an embodiment of the present invention will be described based on an example.
1 to 3 are schematic views showing an image scanner 1 as an image reading apparatus according to an embodiment of the present invention. The image scanner 1 is a so-called flat bed type image scanner. The image scanner 1 can read a reflective original 4 (see FIG. 1A) and a transparent original up to A4 size and A4 letter size. The reflective original 4 as the first object is a printed document, a photograph, or the like. The transparent original as the second object is a 35 mm film (negative / positive film) 6 (see FIG. 1B) or the like. In the following description, it is assumed that the transparent original is a 35 mm film 6. The image reading apparatus may be a sheet feed type image scanner or a multi-function machine. Further, the transparent original is not limited to the 35 mm film 6.

  The housing 8 is formed in a box shape having an upper opening, and supports the document table 10 on the opening side. The document table 10 is formed of a transparent plate such as a generally rectangular glass plate. A 35 mm film 6 held on the reflective original 4 or the holder 14 (see FIG. 1B) is placed on the surface 12 of the original table 10. The 35 mm film 6 fixed to the holder 14 is held at a position 1 mm above the board surface 12 of the document table 10.

  As shown in FIG. 3, a transparent document light source 18 is disposed on the document table 10 side of the document cover 16. The transmissive original light source 18 as the second light source unit includes a fluorescent tube lamp, a reflector, a diffusion plate and the like (not shown). The fluorescent lamp is arranged such that its longitudinal axis extends parallel to the longitudinal axis of the guide rod 20. The reflector is provided on the side opposite to the document table 10 of the fluorescent lamp. The diffusion plate is provided on the same side as the document table 10 of the fluorescent lamp. The light emitted from the fluorescent lamp is reflected by the reflector, diffused by the diffusion plate, and illuminates the reading area A1 (see FIG. 2) of the 35 mm film 6 with uniform illuminance. The fluorescent lamp may be an LED (light emitting diode).

The carriage 22 accommodates the contact image sensor module 2.
FIG. 4 is a schematic diagram showing the contact image sensor module 2 mounted on the image scanner 1.
The contact image sensor module 2 includes a light source 24 for a reflection document, a first rod lens array 26, a second rod lens array 28, a first image sensor 30, a second image sensor 32, and the like. As shown in FIG. 4B, the components of the contact image sensor module 2 are arranged in alignment with respect to each other in the longitudinal center. The longitudinal width of the first image sensor 30 is different from the longitudinal width of the second image sensor 32. Specifically, the width in the longitudinal direction of the arrangement range of the first light receiving elements 31 arranged in the first image sensor 30 is 218 mm so that an A4 size document and an A4 letter size document can be read. The width in the longitudinal direction of the arrangement range of the second light receiving elements 33 arranged in the second image sensor 32 is 27 mm that allows reading of a 35 mm film. The first light receiving element 31 and the second light receiving element 33 will be described later. The width in the longitudinal direction of the light source 24 for the reflection original and the first rod lens array 26 is designed based on the width in the longitudinal direction of the arrangement range of the first light receiving elements 31. The width in the longitudinal direction of the second rod lens array 28 is designed based on the width in the longitudinal direction of the arrangement range of the second light receiving elements 33. The arrangement of the components of the contact image sensor module 2 may be other arrangements. For example, as shown in FIG. 8, the components of the contact image sensor module 2 may be arranged in alignment with respect to one end face in the longitudinal direction. The longitudinal widths of the first image sensor 30 and the second image sensor 32 may be determined according to the document width, and are not limited to 218 mm and 27 mm, respectively.

  As shown in FIG. 1A, the reflection original light source 24, the first rod lens array 26, and the first image sensor 30 are used for the process of reading the reflection original 4. As shown in FIG. 1B, the second rod lens array 28 and the second image sensor 32 are used for the process of reading the 35 mm film 6. The resolution of the first image sensor 30 and the resolution of the second image sensor 32 are different. Specifically, the resolution of the first image sensor 30 is 1200 dpi that can sufficiently reproduce the image information recorded on the reflective original 4. The resolution of the second image sensor 32 is 2400 dpi that can sufficiently reproduce the image information recorded on the 35 mm film 6. Note that the resolution of the first image sensor 30 is not limited to 1200 dpi. Further, the resolution of the second image sensor 32 is not limited to 2400 dpi.

  The reflective original light source 24 as the first light source unit includes an LED that emits light of a specific color and a light guide. Specifically, for example, the reflection original light source 24 emits red light for reading a color image (red LED), green light emitting LED (green LED), and blue light. LED (blue LED) is provided. The light emitted from the LED is guided to the document table 10 side by the light guide to illuminate the reflective document 4. A light guide (not shown) is formed of a light transmissive member such as glass. The first light source unit may include a fluorescent lamp.

  The first rod lens array 26 as the first lens unit has a plurality of cylindrical lenses (rod lenses) 36 arranged linearly. The first rod lens array 26 is a first light receiving element in which an optical image on the scanning line by light emitted from the light source 24 for the reflective original and reflected by the reflective original 4 is arranged on the first image sensor 30 by the first rod lens 36. An image is formed on the 31 light receiving surface at an equal magnification.

  The first image sensor 30 is mounted on the printed circuit board 40. The first image sensor 30 includes a plurality of first light receiving elements 31 and MOS transistor switches arranged in a line in a straight line. The first image sensor 30 scans the optical image of the reflective original 4 formed by the first rod lens array 26 and outputs an electrical signal correlated with the density of the optical image. As a result, the optical image of the reflective original 4 is converted into an image signal.

  The focal length of the first rod lens array 26 and the distance between the first rod lens array 26 and the first image sensor 30 are such that an optical image is clearly formed on the light receiving surface of the first image sensor 30 by the first rod lens array 26. The document is designed so that the position (focal position) of the document to be placed becomes the surface 12 of the document table 10. Therefore, the image scanner 1 can clearly read the reflection document 4 placed on the platen surface 12 on the document table 10.

  The second rod lens array 28 as the second lens unit has the same configuration as the first rod lens array 26 and includes a second rod lens 38. The focal length of the second rod lens array 28 is equal to the focal length of the first rod lens array 26. The second rod lens array 28 irradiates the optical image on the scanning line by the light irradiated from the transmission original light source 18 and transmitted through the 35 mm film 6 on the light receiving surface of the second light receiving element 33 arranged in the second image sensor 32. Doubles the image.

  The second image sensor 32 includes a plurality of second light receiving elements 33, MOS transistor switches, and the like arranged in three rows in parallel with the first light receiving elements 31 of the first image sensor 30, and each of the columns has a different color. A color filter 44 is provided. Specifically, for example, the color filter 44 is a filter (red filter) 44r that transmits red light, a filter (green filter) 44g that transmits green light, and a filter (blue filter) 44b that transmits blue light. Thereby, the white light emitted from the light source 18 for transmissive originals can be separated into red light, green light, and blue light. The second image sensor 32 scans the optical image of the 35 mm film 6 formed by the second rod lens array 28, and outputs an electrical signal correlated with the density of the optical image. Thereby, the optical image of the 35 mm film 6 is converted into an image signal. The color filter 44 has been described as being provided on the second image sensor 32 (on-chip color filter), but may be a separate component from the second image sensor 32.

  The second rod lens array 28 is fixed to the carriage 22 at a position closer to the board surface 12 of the document table 10 by 1 mm than the first rod lens array 26. The second image sensor 32 is mounted on a printed circuit board 42 fixed to the carriage 22 at a position closer to the platen surface 12 of the document table 10 by 1 mm than the printed circuit board 40. Therefore, the light receiving surface of the second light receiving element 33 is closer to the platen surface 12 of the document table 10 by 1 mm than the light receiving surface of the first light receiving element 31. Since the second rod lens array 28 and the light receiving surface of the second light receiving element 33 are arranged at a position close to the platen surface 12 of the document table 10 by 1 mm, the focal point of the second rod lens array 28 and the second image sensor 32 is increased. The position is a position away from the surface 12 of the document table 10 by 1 mm. That is, the image scanner 1 can clearly read the 35 mm film 6 held by the holder 14 at a distance of 1 mm above the platen surface 12 of the document table 10. The height of the second image sensor 32 may be designed to be 1 mm higher than that of the first image sensor 30, and the first image sensor 30 and the second image sensor 32 may be mounted on the same printed circuit board 40. Further, the distance from the platen surface 12 of the document table 10 to the focal position may be determined according to the position where the document is held, and is not limited to 1 mm.

FIG. 5 is a block diagram illustrating a hardware configuration of the image scanner 1.
The main scanning drive unit 50 is a drive circuit that outputs drive pulses necessary for driving the first image sensor 30 and the second image sensor 32 to the first image sensor 30 and the second image sensor 32. The main scanning drive unit 50 includes, for example, a synchronization signal generator, a driving timing generator, and the like.

  The sub-scanning drive unit 52 includes a guide rod 20 that slidably holds the carriage 22, a stepping motor (not shown), a drive belt 46, a drive circuit (not shown), and the like. When the stepping motor pulls the carriage 22 with the driving belt 46, the first image sensor 30 and the second image sensor 32 and the reflective original 4 or the 35 mm film 6 are relatively moved. As a result, a two-dimensional image can be scanned.

  The AFE (analog front end) unit 54 includes an analog signal processing unit (not shown), an A / D converter, and the like. The analog signal processing unit subjects the electrical signals output from the first image sensor 30 and the second image sensor 32 to analog signal processing such as amplification and noise reduction processing, and outputs the result. The A / D converter quantizes the electrical signal output from the analog signal processing unit into an output signal in a digital representation having a predetermined bit length, and outputs the output signal.

  The digital image processing unit 56 performs image processing such as gamma correction, interpolation of defective pixels by a pixel interpolation method, shading correction, image signal sharpening, color space conversion, and the like on the output signal output from the AFE unit 54.

The interface unit 58 is configured in accordance with a communication standard such as RS-232C, Bluetooth, or USB. The image scanner 1 can be communicably connected to a personal computer (PC) (not shown) through the interface unit 58.
The control unit 60 includes a CPU 62, a ROM 64, and a RAM 66. The CPU 62 executes computer programs stored in the ROM 64 to control each unit of the image scanner 1. The ROM 64 is a memory that stores various programs and data, and the RAM 66 is a memory that temporarily stores various programs and data.

  FIG. 6 is a flowchart of processing for reading the reflective original 4. In the process of reading the reflection document 4, the image scanner 1 turns on the LEDs of the respective colors of the light source 24 for the reflection document in a time-division manner while reading one line, thereby reflecting the reflection document 4 for one line by three readings. Read color image data. In the following description, it is assumed that the image scanner 1 is connected to a PC so as to be communicable.

  The user transmits a request to read the reflection original 4 to the image scanner 1 by operating the PC. The image scanner 1 receives a request to read the reflective original 4 via the interface unit 58. When the control unit 60 receives a request to read the reflective original document 4, the control unit 60 controls the sub-scanning drive unit 52 to convey the carriage 22 to the reading start position of the reflective original document 4 (step S100).

In step S <b> 102, the control unit 60 reads the color image of the reflective original 4 with the red LED, the green LED, and the blue LED of the reflective original light source 24 turned on in a time division manner while moving the carriage 22.
Specifically, for example, the control unit 60 turns on the red LED and controls the main scanning drive unit 50 to convert the optical image of the reflection original 4 in the scanning range into an electrical signal (red electrical signal) correlated with the red component. The digital data (red data) correlated with the red component output from the AFE unit 54 is stored in the RAM 66. Next, the control unit 60 turns on the green LED, converts the optical image of the reflection original 4 in the scanning range into an electrical signal (green electrical signal) correlated with the green component, and digital data (green data) correlated with the green component. Is stored in the RAM 66. Next, the control unit 60 turns on the blue LED, converts the optical image of the reflection original 4 in the scanning range into an electrical signal (blue electrical signal) correlated with the blue component, and digital data correlated with the blue component (blue data). Is stored in the RAM 66. When the red data, the green data, and the blue data continuously read at different positions are stored in the RAM 66, the control unit 60 sends the color image data for one line to the digital image processing unit 56 based on the digital data. Is generated.
The controller 60 reads the color image of the reflective original 4 by repeating the reading of the color image data for one line while moving the carriage 22 until the color image data of all the lines of the reflective original 4 is acquired. .
When the reading of the reflective original 4 is completed, the control unit 60 conveys the carriage 22 to the standby position in step S104.

  FIG. 7 is a flowchart of processing for reading the 35 mm film 6. In the process of reading the 35 mm film 6, the optical image of the 35 mm film 6 is converted into an electrical signal correlated with the color component corresponding to the color of the color filter 44 provided in each row by the second light receiving elements 33 arranged in three rows. To do. Specifically, for example, an optical image of the 35 mm film 6 is read once for the red electric signal in the first row of the second light receiving element 33, the green electric signal in the second row, and the blue electric signal in the third row. Convert with. That is, the color image data of the 35 mm film 6 for three lines can be read by three readings (see FIG. 9).

  The user transmits a request for reading the 35 mm film 6 to the image scanner 1 by operating the PC. The image scanner 1 receives a request for reading the 35 mm film 6 via the interface unit 58. When receiving the request for reading the 35 mm film 6, the control unit 60 turns on the fluorescent lamp of the light source 18 for transmissive originals (step S200).

In step S <b> 202, the controller 60 conveys the carriage 22 to the reading start position of the 35 mm film 6.
In step S <b> 204, the control unit 60 converts the optical image of the scanning range of the 35 mm film 6 color-separated by the color filter 44 into an electrical signal correlating to each color component while moving the carriage 22 to change the color of the 35 mm film 6. Read the image. FIG. 9 is a schematic diagram showing a specific example of an operation for reading a color image of the 35 mm film 6. FIG. 9 shows five reading operations from a certain point in time. In this example, it is assumed that reading is repeated at the timing when the carriage 22 moves by the width between the rows of the second light receiving elements 33 arranged in three rows of the second image sensor 32. Positions X1 to X7 indicate reading positions by the second light receiving element 33. The red electrical signals R1 to R5 represent red electrical signals converted at positions X1 to X5, respectively, the green electrical signals G2 to G6 represent green electrical signals converted at positions X2 to X6, respectively, and the blue electrical signal B3 To B7 indicate the blue electrical signals converted at positions X3 to X7, respectively.

The second image sensor 32 outputs a red electrical signal, a green electrical signal, and a blue electrical signal at different positions in one reading. For example, in the first reading, the red electric signal R1 at the position X1, the green electric signal G2 at the position X2, and the blue electric signal B3 at the position X3 are output simultaneously. The electrical signals of the respective color components output from the second image sensor 32 are converted into digital data by the AFE unit 54 and stored in the RAM 66. When the red data, green data, and blue data at the reading position are stored in the RAM 66, the control unit 60 causes the digital image processing unit 56 to generate one line of color image data based on the digital data. For example, when the third reading is completed, the control unit 60 outputs one line based on the red data, the green data, and the blue data correlated with the electrical signal (R3, G3, B3) at the position X3 stored in the RAM 66. Color image data ((R3, G3, B3)) is generated. Similarly, when the fourth reading is completed, the control unit 60 generates one line of color image data ((R4, G4, B4)) at the position X4. When the fifth reading is completed, the control unit 60 generates one line at the position X5. Color image data ((R5, G5, B5)) is generated. That is, color image data for three lines can be read by reading three times.
The control unit 60 reads the color image of the 35 mm film 6 by repeating the reading of one line while moving the carriage 22 until the color image data of all lines is acquired.
When the reading of the color image of the 35 mm film is completed, the control unit 60 turns off the fluorescent lamp of the light source 18 for transmissive originals (step S206) and transports the carriage 22 to the standby position (step S208).

  Since the image scanner 1 according to the embodiment of the present invention described above includes the first image sensor 30 having a resolution of 1200 dpi and the second image sensor 32 having a resolution of 2400 dpi, the reflective original 4 having a low recording density of image information is provided. The 35 mm film 6 having a high recording density of image information can be read by the second image sensor 32 by the first image sensor 30. The reflection original 4 that can be sufficiently reproduced by reading 1200 dpi is not read by the second image sensor 32 of 2400 dpi, but is read by the first image sensor 30 of 1200 dpi, and tends to increase as the resolution of the image sensor increases. Noise generation can be reduced. That is, the image quality of the read image of the reflective original 4 can be improved.

Further, when the white light emitted from the light source 18 for transmissive original is color-separated by the color filter 44 and the image is read by reading the 35 mm film 6 by the second image sensor 32 that reads the image. Compared with, reading time can be shortened.
Furthermore, the width of the 2400 dpi second image sensor 32 in the longitudinal direction is not a width in which the A4 size and the A4 letter size can be read, but 27 mm in accordance with the 35 mm film 6, thereby manufacturing the second image sensor 32. Cost can be reduced. That is, the manufacturing cost of the image scanner 1 can be reduced.

  The contact image sensor module 2 may be provided with a second light source for the reflective original that radiates light reflected by the reflective original 4 and incident on the light receiving surface of the second image sensor 32. Thereby, the reflection original 4 in the range of the reading area A1 of the 35 mm film 6 can be read with high resolution.

1 is a schematic diagram illustrating an image reading apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating an image reading apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating an image reading apparatus according to an embodiment of the present invention. It is a schematic diagram concerning one example of the present invention. 1 is a block diagram of an image reading apparatus according to an embodiment of the present invention. 3 is a flowchart according to an embodiment of the present invention. 3 is a flowchart according to an embodiment of the present invention. It is a schematic diagram concerning one example of the present invention. It is a schematic diagram concerning one example of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image scanner (image reading apparatus), 2 Contact-type image sensor module, 4 Reflected original (1st target object), 6 35mm film (2nd target), 10 Original stand, 18 Light source for transparent originals (2nd light source) , 24 Light source for reflective document (first light source), 26 First rod lens array (first lens portion), 28 Second rod lens array (second lens portion), 30 First image sensor, 31 First light receiving element, 32 Second image sensor, 33 Second light receiving element, 44 Color filter

Claims (2)

A first light source unit that emits light of a plurality of colors in a time-sharing manner and illuminates the first object;
A second light source that emits white light and illuminates the second object, a first image sensor in which a first light receiving element group of one channel is arranged in a straight line, and a second light receiving element group of three channels are A second image sensor arranged in parallel with one light receiving element group and having a resolution different from that of the first image sensor; a first lens unit that forms an image of a first object on the first light receiving element group; and the second light receiving part. A second lens unit that forms an image of the second object on the element group; and a color filter that color-separates white light emitted from the second light source unit and causes the light to enter each channel of the second light receiving element group. A contact image sensor module;
An image reading apparatus comprising:   The image reading apparatus according to claim 1, wherein a width in a longitudinal direction of the arrangement range of the first light receiving element group is different from a width in a longitudinal direction of the arrangement range of the second light receiving element group.

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