JP2008312033A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To read quantity-of-light signals from the same density at a constant level and maintain excellent quality in reading both sides of a document at one time with two document readers. <P>SOLUTION: An image reader has a first document reading means 3 which is placed on one carrying surface on a conveyer 22, and a second document reading means 4 which is placed on another carrying surface. When images on both sides of a document are simultaneously read using the first and second document reading means 3 and 4 at the same scanning rate, both sides of the document are simultaneously read by the first and second document reading means 3 and 4 at a slower scanning rate of two image reading means. Then, the amount of light from a light source of the first or second document reading means with a faster scanning rate is corrected comparing to one-side reading, and irradiation energy is kept constant in one-side and both-side document reading. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that includes at least two document reading units and that can simultaneously read both the front and back surfaces of a document and generate double-sided image data in a single process of transporting the document.

The image reading apparatus is used to read an image of a document and acquire image data by being installed alone or attached to a copying machine, a facsimile machine, a multifunction machine, or the like. In this image reading apparatus, image data is obtained by an original reading apparatus including a light source for irradiating light on a document and a light receiving means such as a CCD for receiving reflected light reflected from the document. The image reading apparatus also includes a conveying unit that conveys the document in addition to reading the image by placing the document on the platen, and irradiates light from the light source to the moving document while conveying the document by the conveying unit. In some cases, the original can be read by receiving the reflected light.
Some originals have images on one side, and others have images on both sides. When reading both the front and back sides of the same document with only one original reading device, A mechanism to reverse is required. Therefore, when both sides are read in the automatic automatic document conveyance / reverse process, the apparatus becomes large and the processing capacity is limited. Since a large tension is applied to the document in the conveyance process, the document may be damaged, and the shape of the document is also limited.

  On the other hand, there has been proposed an image reading apparatus that simplifies the mechanical automatic document transporting process and simultaneously reads both the front and back surfaces of the document in a single process of transporting the document. The image reading device includes two document reading devices, and the document reading devices are arranged one on each side of the transport surface of the document transport path. One document reading device simultaneously reads the front side of the document, and the other document reading device simultaneously reads the back side of the document. In one document reader, light from a light source is irradiated on the surface of the document, and an image sensor receives reflected light from the surface of the document. In the other document reader, light from the light source is applied to the back surface of the document. When the image sensor receives the reflected light from the back side of the original and receives image data on both sides of the original.

By the way, due to spatial limitations of the mechanism of the image reading apparatus, a non-contact type CCD sensor is often used for one of the two document reading apparatuses and a contact type CIS (contact image sensor) is often used for the other. As an apparatus having such a configuration, for example, there is an image reading apparatus described in Patent Document 1. The image reading apparatus sequentially outputs image reading information obtained by the CCD sensor unit and the CIS sensor unit to the image processing unit. The image processing unit writes and reads the image information acquired above to and from the image memory unit, and the CPU sets and controls the image processing unit and reads and writes the image information. Also, a reading mode setting and a reading operation start instruction are performed by the operation unit, and mode setting is performed by the display unit.
JP 2003-264671 A

  By the way, in order to increase the reading operation speed of the image reading apparatus when the image reading apparatus reads both sides of the original, it is conceivable to increase the frequency of the reading clock that defines the scanning speed of the original reading apparatus. However, there is a difference in the inherent scanning speed limit between the CCD sensor and the CIS. In general, the scanning speed of a 1 × optical system using CIS is lower than the scanning speed of a reduction optical system using a CCD sensor. In an image reading apparatus that simultaneously reads both the front and back surfaces of a document in a single process of transporting the document, when the document is scanned on both sides, the scanning operation speed is the same as that of a 1 × optical system using a CIS with a low scanning speed. The scanning speed of the CCD sensor and the CIS must be matched to the scanning speed.

  In order to increase the reading operation speed of the image reading apparatus when the image reading apparatus reads the original on one side, one side of the original is read by a reduction optical system original reading apparatus using a CCD sensor having a high scanning speed. . The scanning speed of the document reader of the reduction optical system using the CCD sensor can be increased to the limit of the scanning speed inherent to the CCD sensor when the image reading of the image reader is single-sided. When reading is performed on both sides, it can only be increased to the limit of the scanning speed inherent to the CIS sensor as described above. For this reason, the scanning speed of the document reading device of the reduction optical system using the CCD sensor differs depending on whether the image reading of the image reading device is one side or both sides.

  The scanning speed is related to the irradiation time indicating the light irradiation time. When the scanning speed is high, the irradiation time is short, and when the scanning speed is low, the irradiation time is long. The scanning speed of a reduction optical system document reader using a CCD sensor is lower when the image reader of the image reader is double-sided than when it is single-sided. The irradiation time of a reduction optical system original reading apparatus using a CCD sensor is longer when the image reading of the image reading apparatus is double-sided than when it is single-sided. As a result, the irradiation energy of the document reading device of the reduction optical system using the CCD sensor becomes larger when reading the document of the image reading device is double-sided than when it is single-sided. When the irradiation energy is different, the light amount signals from the same density of the original image are different, and a difference occurs in the reading quality of the original on both sides of the original.

  The present invention has been made to solve the above-described problem, and keeps the light amount signal from the same density of the original image constant when the original of the image reading apparatus is double-sided or single-sided. An object of the present invention is to provide an image reading apparatus that enables the above.

  That is, among the image reading apparatuses according to the present invention, the invention according to claim 1 is a first document reading unit arranged on one conveyance surface side on a conveyance path on which a document is conveyed and a document conveyance unit that conveys the document. And a second document reading unit disposed on a conveyance surface side different from the conveyance surface side on which the first document reading unit is disposed on the conveyance path, and reads a document image on one side of the document. When one of the first document reading unit and the second document reading unit stops, it reads the document transported along the transport path by the light source included in each of the first document scanning unit and the second document scanning unit at a predetermined single-side scanning speed. When reading the document images on both sides of the document, the first document reading unit and the second document reading unit stop themselves and share the document transported on the transport path by a light source provided in each. At the time, when reading the original images on both sides of the original in the image reading apparatus that reads at the same scanning speed, the predetermined single-side scanning speed in the first original reading means and the predetermined in the second original reading means. The first document reading unit and the second document reading unit stop at a scanning speed which is smaller than the scanning speed at the time of single-sided reading, and read the document images on both sides of the document at the same time. And the first original reading means having a higher scanning speed than the predetermined single-side reading scanning speed of the first original reading means and the predetermined single-side reading scanning speed of the second original reading means, or The amount of light from the light source of the second document reading unit is corrected in comparison with the amount of light from the light source when reading a document image on one side of the document.

In the present invention, a first document reading unit and a second document reading unit are provided, and when reading a document image on one side of a document (hereinafter referred to as single-sided reading), any of the first and second document reading units is provided. The image data can be acquired depending on the situation. There is no particular limitation as to which original reading means performs reading at the time of single-sided reading, but it is usually desirable to use the original reading means having the higher scanning speed at the time of single-sided reading. The selection may be made as an initial setting in advance, or the operator may change the selection as desired. The scanning speed at the time of reading one side of the original in the first and second original reading means is determined in advance in consideration of the reading ability of the reading means. Since the first and second document reading units normally have a difference in reading ability, the scanning speed at the time of single-sided reading differs. The control unit provided in the image reading apparatus controls the document conveying speed by the conveying unit, and conveys the document at a conveying speed that matches the scanning speed of the first or second document reading unit that stops and reads the document itself. To do. Further, the first or second document reading unit may be capable of reading an image of a document placed on a platen or the like by moving as desired.
Each of the first and second document reading units includes a light source, a CCD sensor that receives reflected light reflected from the document surface by the light emitted from the light source, and a CIS as a light receiving unit. . The optical path can include an appropriate optical system such as a reflecting mirror and a lens.

  When the original images on both sides of the original are read using both the first and second original reading means, the first and second original reading means are scanned at the scanning speed corresponding to the scanning speed at the smaller one-side reading. Then, reading is performed by the second document reading unit. At this time, the first or second document reading means having the smaller scanning speed at the time of single-side reading reads at the same scanning speed as the scanning speed at the time of normal single-sided reading. On the other hand, the first or second document reading means having the higher scanning speed at the time of single-side reading reads at a scanning speed lower than the normal scanning speed at the time of single-side reading. As a result, the time that the document is irradiated with light becomes longer, and if the amount of light applied to the document from the light source is the same as that for single-sided scanning, the quality of the image data obtained is that of single-sided scanning. And the quality of the image data obtained from both sides of the document is different.

  Therefore, in the present invention, when reading both sides of a document, it is obtained by correcting the amount of light from the light source in the first or second document reading unit that performs reading at a scanning speed lower than the normal one-side scanning speed. It is possible to reduce or eliminate the difference in the quality of image data. The amount of light can be corrected by changing the light emission intensity by adjusting a current value applied to a light source such as an LED. Further, the correction of the light quantity can be performed by providing a light quantity correction means in the optical path from the light source to the original irradiation surface. It is also possible to provide a plurality of light emitting units as a light source, and to correct the light amount by changing the number of light emitting units that emit light.

  According to a second aspect of the present invention, there is provided the image reading apparatus according to the first aspect, wherein the first original reading means having a higher scanning speed at the time of the one-side reading is read when reading the original images on both sides of the original. By correcting the amount of light from the light source of the second original reading means, the original image on one side of the original in the first original reading means or the second original reading means having a higher scanning speed during the predetermined single-side reading. The irradiation energy for reading the image and the irradiation energy for reading the document images on both sides of the document are made substantially constant.

  According to the second aspect of the present invention, when correcting the amount of light from the light source in the first or second document reading means that performs reading at a scanning speed lower than the normal single-sided scanning speed when reading both sides of the document. In addition, the quality of the acquired image data can be made substantially constant by making the irradiation energy on the original irradiation surface substantially constant during single-sided reading and double-sided reading.

  According to a third aspect of the present invention, there is provided the image reading apparatus according to the second aspect, wherein the irradiation energy is a product of a light amount indicating the intensity of the irradiated light and an irradiation time indicating the time during which the document is irradiated with light. It is defined by.

  According to the third aspect of the present invention, the irradiation energy can be captured by the product of the light amount and the irradiation time on the original irradiation surface, and the correction amount of the light amount from the light source can be easily set.

  According to a fourth aspect of the present invention, there is provided the image reading apparatus according to any one of the first to third aspects, wherein when the original image on both sides of the original is read, the predetermined one-side reading scanning speed is higher. The first document reading unit or the second document reading unit corrects the amount of light from the light source based on the scanning speed of the predetermined one-sided scanning speed, which is smaller, and stops itself so that the original on one side of the document It is characterized by reading an image.

  According to the fourth aspect of the present invention, when correcting the amount of light from the light source in the first or second document reading means in which reading is performed at a scanning speed lower than the normal single-sided scanning speed when reading both sides of the document. In addition, the correction is performed in consideration of the low scanning speed, so that the quality of the obtained document can be kept unchanged between the single-side reading and the double-side reading.

  According to a fifth aspect of the present invention, there is provided the image reading apparatus according to any one of the first to fourth aspects, wherein the first original reading means has a one-side reading scanning speed V1 (mm / sec) and the second original. The scanning speed V2 (mm / sec) at the time of single-sided reading of the reading unit has a magnitude relationship of V1> V2, and when reading original images on both sides of the original, the first original reading unit and the second original reading unit are V2 At the same scanning speed, the document images on both sides of the document are read at the same time, and the light quantity from the light source of the first document reading means is L1 (lx) when reading the document image on one side of the document. ) By correcting L1 * (V2 / V1) (lx) when reading the original images on both sides of the original, the first original reading means uses the irradiation energy when reading the original image on one side of the original, and the original Characterized by the irradiation energy when reading of both sides of the original image substantially constant.

  According to the fifth aspect of the present invention, the correction amount of the light source can be easily determined so that the irradiation energy becomes substantially the same depending on the scanning speed at the time of single-side reading of the first and second document reading units.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the light amount is corrected by adjusting a current value applied to the light source.

  According to the sixth aspect of the present invention, the light emission intensity can be changed by adjusting the value of the current applied to the light source, so that the amount of light for the original can be easily corrected.

  According to a seventh aspect of the present invention, there is provided an image reading apparatus according to any one of the first to sixth aspects, wherein the original image on one side of the original is read and the original image on both sides of the original is read. The change of the document conveying speed in the conveying path is compared with the predetermined single-sided scanning speed in the first original reading unit and the predetermined single-sided scanning speed in the second original reading unit. Control means for correcting the amount of light from the light source of the first document reading unit or the second document reading unit having the higher scanning speed is provided.

  According to the seventh aspect of the invention, according to the single-sided reading and the double-sided reading, the document conveying speed and the correction of the amount of light from the light source can be performed by the control means, and automatic adjustment is performed. The control means can be configured mainly by a CPU and a program for operating the CPU, for example, and may also serve as an apparatus control unit that controls the entire image reading apparatus.

  According to an eighth aspect of the present invention, there is provided the image reading apparatus according to the seventh aspect, wherein the control means reads the first image having a higher scanning speed during single-sided reading when reading the original images on both sides of the original. The correction is performed so as to reduce the light emission intensity of the light source of the original reading means or the second original reading means.

  As described above, according to the image reading apparatus of the present invention, the document conveying unit that conveys the document, the first document reading unit that is disposed on one conveyance surface side on the conveyance path through which the document is conveyed, A second document reading unit disposed on a conveyance surface side different from a conveyance surface side on which the first document reading unit is disposed on the conveyance path, and when reading a document image on one side of the document, One of the first document reading unit and the second document reading unit stops itself and reads the document conveyed by the light source provided at each at a predetermined single-sided scanning speed for each of the documents. When reading a two-sided document image, the first document reading unit and the second document reading unit are stopped at the same time, and the documents transported along the transport path by the light sources provided in the first document reading unit and the second document reading unit are synchronized at the same time. In the image reading apparatus that reads at a scanning speed of 2, when reading the original images on both sides of the original, the scanning speed at the predetermined single-side reading in the first original reading means and the predetermined single-side reading at the second original reading means The first document reading unit and the second document reading unit stop at a scanning speed that is smaller than the scanning speed and read the document images on both sides of the document at the same time. The first original reading means or the second original having a higher scanning speed than the predetermined single side reading scanning speed of the first original reading means and the predetermined single side reading scanning speed of the second original reading means. When reading both sides of the document, the amount of light from the light source of the reading means is corrected compared to the amount of light from the light source when reading the document image on one side of the document. Both sides can be read by transporting the document once, and the light intensity signal from the same density of the document image can be kept constant when the document is read by the image reading device on both sides and on one side. The design of image processing at the subsequent stage of the reading apparatus can be facilitated.

  Further, by optimizing the scanning speed of the document reading device when reading a document image on one side of the document and the scanning speed of the document reading device when reading the document image on both sides of the document, the capability of the image reading device is enhanced. Can keep.

The best mode for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing the configuration of an image reading apparatus in which the present invention is implemented.
The image reading apparatus 1 includes an automatic document conveying device 2 that is a conveying unit, a first document reading device 3 that is a first document reading unit, a second document reading device 4 that is a second document reading unit, and a document reading control device described later. 5, an image processing device 6 and an input / output interface 7 are provided.

The automatic document feeder 2 sequentially feeds the documents one by one from the document tray 20 to the discharge tray 23 on the conveyance path 22, and the first document reading device 3 and the second document reading device 4 in the middle of the document image Causes scanning and reading.
The automatic document feeder 2 includes the document tray 20, a pickup roller 21a, a feed roller 21b, a pre-registration roller 21c, a registration roller 21d, a platen roller 21e, an out roller 21f, a discharge roller 21g, and the discharge tray 23. The document tray 20 is a place where one document or a plurality of documents are stacked and stacked. The pickup roller 21 a conveys a document positioned at the top of the bundle of documents placed on the document tray 20. The feed roller 21b conveys the document one sheet at a time downstream of the conveyance path 22. The pre-registration roller 21 c aligns the leading edge of the document with the position of the registration roller 21 d located downstream of the conveyance path 22. The registration roller 21 d conveys the document to the document reading positions of the first document reading device 3 and the second document reading device 4 in accordance with the document reading start timing of the first document reading device 3 and the second document reading device 4. The platen roller 21 e presses the document at the document reading position of the first document reading device 3 against the platen glass 10. The out roller 21 f conveys the document downstream of the conveyance path 22 while keeping the speed of the document passing through the document reading positions of the first document reading device 3 and the second document reading device 4 constant. The paper discharge roller 21g discharges the conveyed document to the discharge tray 23. The discharge tray 23 is a place where a document on which a document image has been read by the image reading device 1 is stacked.

  As described above, the automatic document feeder 2 starts conveying the document located at the top of the document bundle on the document tray 20 by the pickup roller 21a. The originals conveyed by the pickup roller 21a are conveyed one by one to the downstream of the conveyance path 22 by the feed roller 21b, and the leading edge of the original is adjusted to the position of the registration roller 21d which is stopped downstream of the conveyance path 22 by the pre-registration roller 21c. The automatic document feeder 2 corrects deviations in the position and angle of the document caused by the transportation process by the pre-registration roller 21c. Further, in the automatic document feeder 2, the registration roller 21 d is rotated in accordance with the document reading start timing of the first document reading device 3 and the second document reading device 4, so that the document is fed to the first document reading device 3 and the second document reading device. The document is conveyed to the document reading position of the reading device 4, and the document at the document reading position of the first document reading device 3 is pressed against the platen glass 10 by the platen roller 21e. The platen roller 21e prevents defocusing of the original reading of the first original reading device 3 caused by the floating of the original in the conveying process. The automatic document conveying device 2 further conveys the document downstream of the conveying path 22 while maintaining the speed of the document passing through the document reading positions of the first document reading device 3 and the second document reading device 4 by the out roller 21f. The deviation of the position and angle of the document caused by the conveyance process and the accuracy of document reading by the first document reading device 3 and the second document reading device 4 are corrected by the out roller 21f, and the document image is corrected by the paper discharge roller 21g. The document that has been read is discharged to the discharge tray 23.

  The first document reading device 3 and the second document reading device 4 scan an original document that has moved and stopped, or scan an original document that has stopped and moved, and read an original image. 6 outputs an image signal. The document reading control device 5 shown in FIG. 5 comprehensively controls the entire processing of document reading by the automatic document feeder 2, the first document reading device 3, and the second document reading device 4. The image processing device 6 performs predetermined processing on the image signals obtained by the first document reading device 3 and the second document reading device 4 and converts them into image data effective for the output device. The input / output interface 7 receives a control signal from an output device (not shown), and can output image data to the output device in synchronization with the control signal.

  The first document reading device 3 includes a scanning light source unit 30, a scanning mirror unit 31, an imaging lens 32, and a CCD image sensor 33. FIG. 2 is an outline view showing the overall configuration of the first document reading device 3. The scanning light source unit 30 includes a light source 30a and a first mirror 30b. The light source 30 a irradiates the original with light, and the first mirror 30 b receives the reflected light from the original and reflects it to the scanning mirror unit 31. The scanning mirror unit 31 includes a second mirror 31a and a third mirror 31b. The second mirror 31a receives the reflected light from the scanning light source unit 30 and reflects it to the third mirror 31b. The third mirror 31 b receives the reflected light from the second mirror 31 a and reflects it to the imaging lens 32. The imaging lens 32 receives the reflected light from the scanning mirror unit 31 and forms an image on the light receiving surface of the CCD image sensor 33.

  The CCD image sensor 33 is composed of a CCD (Charge Coupled Device) that is a solid-state imaging device. The CCD image sensor 33 reads the amount of light imaged by the imaging lens 32 as a light amount signal. The light amount signal is converted into an electrical signal by photoelectric conversion by the solid-state imaging device and output. The CCD image sensor 33 is a one-dimensional sensor and can simultaneously convert a light amount signal for one line into an electric signal.

  The first document reading device 3 described above can read a document image by scanning a document that has moved and stopped, and can output an image signal to the image processing device 6. When reading a document placed on the platen glass 10, the first document reading device 3 moves the scanning light source unit 30 and the scanning mirror unit 31 in the scanning direction at a rate of 2: 1. The scanning light source unit 30 moves from the leading end to the trailing end of the document, and the scanning mirror unit 31 moves a distance that is ½ of the moving distance of the scanning light source unit 30. When the scanning light source unit 30 moves from the leading end to the trailing end of the document, the first document reading device 3 turns on the light source 30a of the scanning light source unit 30 and irradiates the document with light. The first document reading device 3 receives reflected light from the document and reflects the light sequentially in order to the first mirror 30b of the scanning light source unit 30, the second mirror 31a of the scanning mirror unit 31, and the third mirror 31b. The light is condensed on the lens 32. The reflected light from the original focused on the imaging lens 32 forms an image on the light receiving surface of the CCD image sensor 33. The light amount signal of the document image is converted into an electrical signal by photoelectric conversion by the CCD image sensor 33 that receives the reflected light from the document. In the first document reading device 3, when the photoelectric conversion process for one line of the document image is completed, the scanning light source unit 30 and the scanning mirror unit 31 are moved in the scanning direction to read the next one line of the document. The first original reading device 3 reads one original by reading the original one line at a time and converting the original image into an electric signal line by line for all the originals. The obtained electrical signal of the document image is output to the image processing device 6 as an image signal.

  Further, the first document reading device 3 can read a document image by scanning a document that stops and moves, and can output an image signal to the image processing device 6. In the first document reading device 3, when reading a document conveyed by the automatic document conveying device 2, the scanning light source unit 30 and the scanning mirror unit 31 are stopped at a predetermined document reading position on the platen glass 10. In the first document reader 3, when the automatic document feeder 2 passes the document reading position from the leading edge to the trailing edge of the document, the light source 30 a of the scanning light source unit 30 is turned on to irradiate the document with light. The first document reading device 3 receives reflected light from the document and reflects the light sequentially in order to the first mirror 30b of the scanning light source unit 30, the second mirror 31a of the scanning mirror unit 31, and the third mirror 31b. The light is condensed on the lens 32. The reflected light from the document focused on the imaging lens 32 is imaged on the light receiving surface of the CCD image sensor 33, and the light amount signal of the document image is converted into an electrical signal by photoelectric conversion by the CCD image sensor 33. When the photoelectric conversion process for one line of the original image is completed, the first original reading device 3 reads the next one line of the original conveyed by the automatic original conveying apparatus. One original is read by reading the original one line at a time and converting the original image into an electric signal line by line for all the originals. The obtained electrical signal is output to the image processing device 6 as an image signal.

  On the other hand, the second document reading device 4 includes a light source unit 40, a rod lens array 41, and a line sensor unit 42 as shown in FIG. FIG. 3 is an outline view showing the overall configuration of the second document reading device 4. The second document reading device 4 employs a 1 × optical system using a rod lens array 41 and a line sensor unit 42. The line sensor unit 42 uses a CIS (Contact Image Sensor) that is simple in configuration and can be downsized due to the limitations of the mechanism of the entire image reading apparatus.

  The light source unit 40 includes an LED 40a, a light guide 40b, and a holding member 40c. A plurality of LEDs 40a are used and arranged two-dimensionally or three-dimensionally. If it is arranged three-dimensionally, the amount of light emission can be increased compared to the case where it is arranged two-dimensionally. If the required amount of light emission can be obtained, one LED may be used. When reading a color image, LEDs of red (red), green (green), and blue (blue) are used. The light guide 40b is formed of a light transmissive member such as glass. The light guide 40b has a diffusing surface and an exit surface. A reflective sheet having a high light reflectance is applied to the diffusing surface of the light guide 40b, or a reflective film having a high light reflectance is applied or deposited. To increase the diffusion rate. Further, the exit surface of the light guide 40b is disposed in the opening of the holding member 40c.

  The light emitted from the LED 40a is incident on the light guide 40b, and the light diffused on the diffusion surface of the light guide 40b is emitted from the emission surface of the light guide 40b disposed in the opening of the holding member 40c. The light emitted from the light exit surface of the light guide 40b is configured to irradiate the original. If the light exit surface of the light guide 40b is formed in a lens shape, the original can be illuminated more brightly. The holding member 40c is formed of a light impermeable member having a high light reflectance. The inner surface of the holding member 40c is coated with a reflective sheet having a high light reflectivity, or a reflective film having a high light reflectivity is applied or deposited, thereby increasing the reflectivity. The holding member 40c is guided across an air layer. It is formed so as to cover the light body 40b. In the holding member 40c, the light leaked from the light guide 40b is incident on the light guide 40b again. By installing the holding member 40c, it is possible to reduce the attenuation loss of light. The lighting timing of the LED 40a is controlled by the light source driver 55 of the document reading control device 5 shown in FIG.

  The rod lens array 41 is composed of a plurality of cylindrical lenses (rod lenses 41a) arranged in a line in a predetermined direction. The arrangement direction of the rod lens 41a is the same as the direction in which the plurality of solid-state imaging elements 42a constituting the line sensor unit 42 are arranged. Each rod lens 41a is installed in one-to-one correspondence with each solid-state imaging element 42a of the line sensor unit 42. The rod lens array 41 receives the reflected light from the original and forms an image on the solid-state image sensor 42a at the same magnification as the original. On the line sensor unit 42, an optical image of the reading portion of the document is formed.

  The line sensor unit 42 is composed of a plurality of solid-state imaging elements 42a arranged in a line in a predetermined direction, and the rod lens array 41 is arranged in the predetermined direction in which the solid-state imaging element 42a is arranged as described above. The same as the predetermined direction. And the solid-state image sensor 42a of the line sensor unit 42 is arrange | positioned corresponding to the rod lens 41a one-to-one. The solid-state imaging device 42a reads the magnitude of the amount of light imaged by the rod lens array 41 as a light amount signal at a predetermined cycle. The light quantity signal is converted into an electrical signal by photoelectric conversion by the solid-state imaging element 42a and output. In the line sensor unit 42, the received light in a predetermined wavelength region is photoelectrically converted by the solid-state imaging device 42a such as a photodiode into electric charge, and accumulated for a predetermined time. The electric charge accumulated for each solid-state imaging element 42a is output for a predetermined time using a MOS transistor switch or the like as an electric signal corresponding to the light quantity signal. The time during which the CIS converts received light into charges and accumulates it is defined as a photoelectric conversion period, and the time during which accumulated charges are output is defined as a charge output period. The timing of the CIS photoelectric conversion period and the charge output period is controlled by the sensor driver 56 of the document reading control device 5.

  The second document reading device 4 scans a document that stops and moves, reads a document image, and outputs an image signal to the image processing device 6. The second document reading device 4 reads a document conveyed by the automatic document conveying device 2. The second document reading device 4 is installed at a predetermined document reading position between the platen roller 21e and the out roller 21f of the document transport path 22. In the second document reading device 4, the LED 40 a of the light source unit 40 is turned on when the automatic document feeder 2 passes the document reading position from the leading edge to the trailing edge of the document. The light emitted from the LED 40a is incident on the light guide 40b, and the light diffused on the diffusion surface of the light guide 40b is emitted from the emission surface of the light guide 40b disposed in the opening of the holding member 40c. . The light emitted from the light exit surface of the light guide 40b is applied to the document. In the second document reading device 4, the reflected light from the document is received and condensed on the rod lens array 41. The reflected light from the original focused on the rod lens array 41 is imaged on the light receiving surface of the line sensor unit 42, and the light quantity signal of the original image is converted into an electrical signal by photoelectric conversion by the line sensor unit 42. When the photoelectric conversion processing for one line of the original image is completed, the second original reading device 4 reads the next line of the original conveyed by the automatic original conveying device 2. The second original reading device 4 reads one original by reading the original one line at a time and converting the original image into an electric signal line by line for all the originals. The obtained electrical signal of the document image is output to the image processing device 6 as an image signal.

  When the second document reading device 4 reads a document transported by the automatic document transport device 2, as shown in FIG. 4, a control member that controls the dynamic displacement of the transported document at the document reading position of the transport path 22 43a and a pressing member 43b may be provided as a target when the conveyed document is pressed by the control member 43a. FIG. 4 is a view showing the periphery of the second document reading device 4. The control member 43a and the pressing member 43b are installed facing each other. The document is conveyed between the control member 43a and the pressing member 43b. The distance between the control member 43a and the pressing member 43b can vary according to the thickness of the document being conveyed. Even when the document is folded or curled, the document is pressed against the pressing member 43b by the control member 43a when passing through the document reading position of the second document reading device 4. By the control member 43a and the pressing member 43b, the document can stably pass through the document reading position of the second document reading device 4. Since the second document reading device 4 uses the rod lens array 41 as an optical imaging lens, the depth of focus is relatively shallow at ± 0.3 mm. In order for the line sensor unit 42 to read a document normally, it is necessary to control the reading position of the document within a specified range. A control member 43a and a pressing member 43b are provided. When the document is conveyed between the control member 43a and the pressing member 43b and the document passes through the document reading position of the line sensor unit 42, the control member 43a presses the document. By pressing to 43b, the height of the original at the original reading position of the line sensor unit 42 can be stabilized, and the defocus of original reading due to the CIS having a shallow depth of focus can be prevented. Thereby, the document reading defocusing of the second document reading device 4 caused by the document floating caused by the document conveying process is avoided.

The document reading control device 5 serving as a control unit includes a CPU 50, a ROM 51, a RAM 52, a memory 53, a motor driver 54, a light source driver 55, and a sensor driver 56. FIG. 5 is a block diagram showing the overall configuration of the document reading control device 5, the image processing device 6, and the input / output interface 7.
The CPU 50 includes a ROM 51 that stores a program and various reference data for comprehensively controlling the entire document reading process by the automatic document feeder 2, the first document reading device 3, and the second document reading device 4. The entire document reading process by the automatic document feeder 2, the first document reading device 3, and the second document reading device 4, together with a RAM 52 in which programs and various data are temporarily stored and a rewritable memory 53 such as an EPROM. Overall control. Further, the CPU 50 controls the motor driver 54, the light source driver 55, the sensor driver 56, the analog signal processing unit 60 and the digital signal processing unit 61 constituting the image processing apparatus 6, and the operations of the respective units to The entire document reading process by the first document reading device 3 and the second document reading device 4 is comprehensively controlled.

  The motor driver 54 picks up the roller 21a, the feed roller 21b, the pre-registration roller 21c, the registration roller 21d, the platen roller 21e, the out roller 21f, the paper discharge of the automatic document feeder 2 in order to move the document at a predetermined timing and at a predetermined speed. The rotational drive of a pulse motor (not shown) of the roller 21g is controlled. By controlling the rotation of the pulse motor by the motor driver 54, the rotation timing of the pickup roller 21a, the feed roller 21b, the pre-registration roller 21c, the registration roller 21d, the platen roller 21e, the out roller 21f, and the discharge roller 21g of the automatic document feeder 2 Determine the rotation speed. According to the rotation timing and rotation speed of these rollers, the movement timing and movement speed of the document on the conveyance path 22 from the document tray 20 to the discharge tray 23 are determined.

  The light source driver 55 controls the timing of turning on and off the light sources of the first document reading device 3 and the second document reading device 4. That is, the light source driver 55 turns off the light source 30a of the first document reading device 3 until the leading edge of the document reaches a predetermined document reading position of the first document reading device, and the first document from the leading edge to the trailing edge of the document. When passing through a predetermined document reading position of the reading device 3, the light source 30a of the first document reading device 3 is turned on. Further, the light source driver 55 turns off the light source 30 a of the first document reading device 3 after the trailing edge of the document has passed a predetermined document reading position of the first document reading device 3.

  Further, the light source driver 55 turns off the light source 40a of the second document reading device 4 until the leading end of the document reaches a predetermined document reading position of the second document reading device 4, and the second portion extends from the leading end to the trailing end of the document. When passing a predetermined document reading position of the document reading device 4, the light source 40a of the second document reading device 4 is turned on. After the trailing edge of the document passes a predetermined document reading position of the second document reading device 4, the light source 40a of the second document reading device 4 is turned off. Then, the first document reading device 3 reads a document while the light source 30a of the first document reading device 3 is turned on, and the second document reading device 4 is turned on the light source 40a of the second document reading device 4. Read the document while

  The sensor driver 56 drives solid-state image sensors corresponding to the light receiving portions of the first document reading device 3 and the second document reading device 4. That is, the sensor driver 56 controls the period of the photoelectric conversion period and the charge output period of the solid-state image sensor, and charges accumulated in the solid-state image sensor during the photoelectric conversion period are transferred from the document reader to the image processing device 6 during the charge output period. To the analog signal processing unit 60.

  The image processing device 6 includes an analog signal processing unit 60 and a digital signal processing unit 61. The image processing device 6 receives image signals of document images from the first document reading device 3 and the second document reading device 4. The image processing device 6 performs predetermined processing on the image signal and converts it into image data effective for the output device. The analog signal processing unit 60 includes an analog signal correction unit 60a and an A / D conversion unit 60b. The analog signal correction unit 60a performs analog signal processing such as offset correction, amplification correction, and noise removal on the analog electric signal output from the document reading apparatus and outputs an analog image signal. The A / D conversion unit 60b converts the analog image signal output from the analog signal correction unit 60a into digital image data having a predetermined bit depth.

  The digital signal processing unit 61 performs digital signal processing such as shading correction by the shading correction unit 61a, γ correction, defective pixel interpolation processing, and filter processing on the digital image data output from the analog signal processing unit 60. A part or all of various digital signal processing performed by the digital signal processing unit 61 can be performed by the CPU by a program.

  The input / output interface 7 outputs the digital image data output from the digital signal processing unit 61 to a connected output device. The document reading control device 5 is connected to an output device via an input / output interface 7. The document reading control device 5 receives a control signal from the output device, and outputs digital image data to the output device in synchronization with the control signal.

Next, the operation of the image reading apparatus in which the present invention is implemented will be described. FIG. 6 is a flowchart showing an initial operation of the image reading apparatus in which the present invention is implemented.
In this initial operation, it is determined whether the image reading is double-sided original reading or single-sided original reading (step s1). An operator can select whether to read a double-sided document or a single-sided document using an operation panel (not shown), and either a double-sided document reading or a single-sided reading is set as an initial setting in advance.
By this determination, a single-sided original reading process (step s2) or a double-sided original reading process (step s3) is performed.

The operation of the image reading apparatus when the original is read on one side will be described with reference to the flowcharts of FIGS.
When one document or a plurality of documents are stacked on the document tray 20, it is determined that there is a document on the document tray 20 (step s201), and the process proceeds to the next step. In the next step, it is determined whether there is a reading start command from the document reading control device 5 (step s202). The single-sided reading start command is issued by a start command operation by an operator, detection of a document placed on the document tray 20, or the like.
The automatic document feeder 2 starts conveying the document located at the top of the bundle of documents on the document tray 20 by the rotation of the pickup roller 21a (step s203). The automatic document feeder 2 conveys the document conveyed by the pickup roller 21a one sheet at a time downstream of the conveyance path 22 by the feed roller 21b (step s204). The automatic document feeder 2 rotates the pre-registration roller 21c to align the leading edge of the document with the position of the registration roller 21d that is stopped downstream of the conveyance path 22 (step s205).

  When the original is read on one side, the reading operation speed of the image reading apparatus depends only on the scanning speed of the original reading apparatus used for reading. Therefore, if the first document reading device 3 having a larger scanning speed is used, the document can be conveyed and read at a higher speed in accordance with the optimum scanning speed.

  The first document reading device 3 stops the scanning light source unit 30 and the scanning mirror unit 31 at a predetermined document reading position on the platen glass 10 when reading the document conveyed by the automatic document conveying device 2. When the leading edge of the document reaches the position of the registration roller 21d (step s206), the document reading control device 5 stops the rotation of the registration roller 21c (step s207), and sets the timer 1 and timer 3 (step s208).

  When there is a notification of completion of document reading preparation of the first document reading device 3 (step s209), the automatic document feeder 2 rotates the registration roller 21d (step s210), whereby the document is read from the document of the first document reading device 3. Transport to the reading position. A document position sensor is provided in the vicinity of the registration roller 21 d in the transport path 22, and the document position sensor detects the position of the document on the transport path 22. When the document position sensor detects whether or not the document has passed the observation point of the document position sensor, and the document position sensor detects the leading edge of the document that starts passing through the observation point (step s211), the document reading control device 5 sets a timer. A countdown of 1 is started (step s212). When the timer 1 becomes 0, it indicates the time when the leading edge of the document reaches the document reading position of the first document reading device. When the timer 1 reaches 0 (step s213), the document reading control device 2 turns on the light source 30a and causes the first document reading device 3 to start reading a document (step s214). The automatic document feeder 2 presses the document at the document reading position of the first document reading device 3 against the platen glass 10 by the platen roller 21e (step s215).

  In the first document reading device 2, when the automatic document feeder 2 passes the document reading position from the leading edge to the trailing edge of the document, the light source 30a of the scanning light source unit 30 is turned on as described above to emit light to the document. Irradiate. The first document reading device 3 receives the reflected light from the document, collects it through the scanning light source unit 30, the scanning mirror unit 31, and the imaging lens 32 as described above, and performs photoelectric conversion by the CCD image sensor 33. Thus, the light quantity signal of the document image is converted into an electric signal. When the photoelectric conversion process for one line of the original image is completed, the first original reading device 3 reads the next one line of the original conveyed by the automatic original conveying device 2. One original is read by reading the original one line at a time and converting the original image into an electric signal line by line for all the originals. The electrical signal of the document image is output to the image processing device 6 as an image signal. When the original is read on one side, the reading operation speed of the image reading apparatus depends only on the scanning speed at the time of single-sided reading of the first original reading apparatus.

  The image processing device 6 inputs an image signal of a document image from the first document reading device 3, performs predetermined processing on the image signal by the analog signal processing unit 60 and the digital signal processing unit 61 as described above, and outputs the image signal. Convert to valid image data.

  The automatic document feeder 6 conveys the document downstream of the conveyance path 22 while keeping the speed of the document passing the document reading position of the first document reading device 3 constant by the out roller 21f (step s216). When the document position sensor detects the trailing edge of the document after the document has passed the observation point (step s217), the document reading control device 5 starts a countdown of the timer 3 (step s218). When the timer 3 reaches 0, it indicates the time when the trailing edge of the document reaches the document reading position of the first document reading device. When the timer 3 reaches 0 (step s219), the document reading control device 2 ends the reading of the document by the first document reading device 3 (step s220). The first document reading device 3 turns off the light source of the scanning light source unit and finishes reading a series of documents. Further, the automatic document feeder 2 discharges the document whose document image has been read by the discharge roller 21g to the discharge tray (steps s221 and 222).

  When a document remains on the document tray 20, the automatic document feeder 2 starts transporting the document located at the top of the document bundle on the document tray 20 by the pickup roller 21a (to step s203). Repeat the series of operations. When no document remains on the document tray, the image reading apparatus finishes reading the document (step s223).

Next, the operation of the image reading apparatus when the original is read on both sides will be described with reference to the flowcharts of FIGS.
When one document or a plurality of documents are stacked on the document tray 20, it is determined that there is a document on the document tray 20 (step s301), and the process proceeds to the next step. In the next step, it is determined whether or not there is a reading start command from the document reading control device 5 (step s302). The double-sided reading start command is issued by a start command operation by an operator, detection of a document placed on the document tray 20, or the like. The automatic document feeder 2 starts conveying the document located at the top of the bundle of documents on the document tray 20 by the rotation of the pickup roller 21a (step s303). The automatic document feeder 2 conveys the document conveyed by the pickup roller one sheet at a time downstream of the conveyance path by the feed roller 21b (step s304). The automatic document feeder 2 rotates the pre-registration roller 21c to align the leading edge of the document with the position of the registration roller 21d that is stopped downstream of the conveyance path 22 (step s305).

  When the document is read on both sides, the document conveyance speed is the same for both the first document reading device 3 and the second document reading device 4. The reading operation speed of the image reading device depends on the scanning speed of the lower one of the scanning speed of the first document reading device 3 and the scanning speed of the second document reading device 4. In the image reading apparatus of this embodiment, the first document reading device 3 uses a CCD sensor, and the second document reading device 4 uses a CIS. The scanning speed of CIS is generally relatively small relative to the scanning speed of the CCD sensor. The reading operation speed of the image reading device depends on the CIS scanning speed of the second document reading device 4, and the document conveying speed is set in accordance with the scanning speed.

  The first document reading device 3 stops the scanning light source unit 30 and the scanning mirror unit 31 at a predetermined document reading position on the platen glass 10 when reading the document conveyed by the automatic document conveying device 2. When the leading edge of the document reaches the position of the registration roller 21d (step s306), the document reading control device 2 stops the rotation of the pre-registration roller 21c (step s307) and sets the timers 1 to 4 (step s308).

  When notification of completion of document reading preparation of the first document reading device 3 and the second document reading device 4 is received (step s309), the automatic document feeder 2 rotates the registration roller 21d (step s310), and the document is first printed. The first document reading device 3 and the second document reading device 4 are transported to the document reading position. Then, it is detected whether or not the original passes through the observation point of the original position sensor. When the document position sensor detects the leading edge of the document that starts to pass through the observation point (step s311), the document reading control device 2 starts counting down timers 1 and 2 (step s312). When the timer 1 reaches 0 (step s313), it indicates the time when the leading edge of the document reaches the document reading position of the first document reading device. When the timer 1 reaches 0, the document reading control device causes the first document reading device 3 to start reading a document (step s314). The automatic document feeder 2 presses the document at the document reading position of the first document reading device 3 against the platen glass 10 by the platen roller 21e (step s315). When the timer 2 reaches 0, the time when the leading edge of the document reaches the document reading position of the second document reading device 4 is indicated. When the timer 2 reaches 0 (step s316), the document reading control device 2 causes the second document reading device to start reading a document (step s317).

  When the automatic document feeder 2 passes the document reading position from the leading edge to the trailing edge of the document, the first document reading device 3 turns on the light source 30a of the scanning light source unit 30 and irradiates the document with light. The first document reading device 3 has a scanning speed at the time of double-sided reading that is lower than the scanning speed at the time of single-sided reading, and the light emission intensity of the light source 30a is adjusted by adjusting the current value for the light source 30a. It correct | amends so that it may decrease. The first document reading device 3 receives reflected light from the document and forms an image on the light receiving surface of the CCD image sensor 33 through the scanning light source unit 30, the scanning mirror unit 31, and the imaging lens 32 as described above. . The light amount signal of the document image is converted into an electric signal by photoelectric conversion by the CCD image sensor 33. When the photoelectric conversion process for one line of the original image is completed, the first original reading device 3 reads the next line of the original conveyed by the automatic original conveying device 2, reads the original one line at a time, and reads the original image. One original is read by executing conversion to an electric signal line by line for all the originals. The electrical signal of the document image is output to the image processing device 6 as an image signal.

When the document passes through the document reading position of the second document reading device 4, the document is pressed against the pressing member 43b by the control member 43a.
The second document reading device 4 turns on the LED 40a of the light source unit 40 when the automatic document feeder 2 passes the document reading position from the leading edge to the trailing edge of the document. In the second document reading device 4, the scanning speed for single-sided reading and the scanning speed for double-sided reading are the same, and the light emission intensity of the LED 40a is the same as that for single-sided reading.

  The light emitted from the LED 40 a is incident on the light guide 41, and the light diffused on the diffusion surface of the light guide 41 is emitted from the emission surface of the light guide 41 disposed in the opening of the holding member 42. The document is irradiated. The second document reading device 4 receives the reflected light from the document, collects it on the rod lens array 41, and forms an image on the light receiving surface of the line sensor unit 42. The light amount signal of the document image is converted into an electric signal by photoelectric conversion by the line sensor unit 42. When the photoelectric conversion processing for one line of the original image is completed, the second original reading device 4 reads the next line of the original conveyed by the automatic original conveying device 2 and reads the original one line at a time. One original is read by executing conversion to an electric signal line by line for all the originals. The electrical signal of the document image is output to the image processing device 6 as an image signal.

  In the image processing device 6, image signals of document images are input from the first document reading device 3 and the second document reading device 4. The image processing device 6 performs predetermined processing on the image signals from the first document reading device 3 and the second document reading device 4 by the analog signal processing unit 60 and the digital signal processing unit 61, respectively, as described above. Convert to image data valid for the output device.

  The automatic document feeder 2 conveys the document downstream of the conveyance path 22 while keeping the speed of the document passing through the document reading positions of the first document reading device 3 and the second document reading device 4 by the out roller 21f (step). s318). When the document position sensor detects the trailing edge of the document after the document has passed the observation point (step s319), the document reading control device 5 starts counting down timers 3 and 4 (step s320). When the timer 3 becomes 0, the time when the trailing edge of the document reaches the document reading position of the first document reading device 3 is indicated. When the timer 3 reaches 0 (step s321), the document reading control device 5 ends the reading of the document by the first document reading device 3 (step s322). When the timer 4 reaches 0, it indicates the time when the trailing edge of the document reaches the document reading position of the second document reading device. When the timer 4 reaches 0 (step s323), the document reading control device 5 ends the reading of the document by the second document reading device 4 (step s324).

The first document reading device 3 turns off the light source 30a of the scanning light source unit 3 and finishes reading a series of documents. The second document reading device 4 turns off the LED 40a of the light source unit 40 and finishes reading a series of documents.
The automatic document feeder 2 discharges the document whose document image has been read by the discharge roller 21g to the discharge tray 23 (steps s325 and 326).
When the document remains on the document tray 20, the automatic document feeder 2 starts transporting the document located at the top of the document bundle on the document tray 20 by the pickup roller 21a (to step s303), and Repeat a series of actions. When no document remains on the document tray (step s327), the image reading apparatus finishes reading the document.

  FIG. 13 is a timing chart showing an operation when the image reading apparatus of the present invention reads both sides of a document. The document position sensor device detects the position of the document on the conveyance path 22 and detects whether or not the document passes through the observation point of the document position sensor device. The document position sensor device outputs a 1 signal when the document passes the observation point of the document position sensor device, and a 0 signal when the document does not pass.

  When the document position sensor device detects the leading edge of the document that starts passing through the observation point, the output signal from the document position sensor device changes from 0 to 1. When the output signal from the document position sensor device changes from 0 to 1, the document reading control device 5 starts counting down timers 1 and 2. When the timer 1 reaches 0, the time when the leading edge of the document reaches the reading point of the first document reading device 3 is indicated. The document reading control device 5 causes the first document reading device 3 to start document reading processing. The first document reading device 3 turns on the light source and starts a series of document reading processes. When the timer 2 reaches 0, it indicates the time when the leading edge of the document reaches the reading point of the second document reading device 4. The document reading control device 5 causes the second document reading device 4 to start document reading processing. The second document reading device 4 turns on the light source and starts a series of document reading processes.

  When the document position sensor device detects the trailing edge of the document that has passed the observation point, the output signal from the document position sensor device changes from 1 to 0. When the output signal from the document position sensor device changes from 1 to 0, the document reading control device starts to count down timers 3 and 4. When the timer 3 reaches 0, it indicates the time when the trailing edge of the document reaches the reading point of the first document reading device 3. The document reading control device 5 causes the first document reading device 3 to finish the document reading process. The first document reading device 3 turns off the light source and ends a series of document reading processing. When the timer 4 becomes 0, it indicates the time when the trailing edge of the document reaches the reading point of the second document reading device 4. The document reading control device 5 causes the second document reading device 4 to finish the document reading process. The second document reading device 4 turns off the light source and ends a series of document reading processing.

As described above, the reading point of the first document reading device 3 and the reading point of the second document reading device 4 are relatively distant from each other in the document conveyance path direction. The reading point of the first document reading device 3 is located upstream of the reading point of the second document reading device 4 in the document conveyance path direction. The document first passes through the reading point of the first document reading device 3 and then passes through the reading point of the second document reading device 4. The leading edge of the document passes through the reading point of the first document reading device 3 when the timer 1 becomes 0, and passes through the reading point of the second document reading device 4 when the timer 2 becomes 0. The trailing edge of the document passes through the reading point of the first document reading device 3 when the timer 3 becomes 0, and passes through the reading point of the second document reading device 4 when the timer 4 becomes 0. The time from when the timer 1 becomes 0 to when the timer 3 becomes 0 is the time during which the document passes the reading point of the first document reading device 3. The time from when the timer 2 becomes 0 to when the timer 4 becomes 0 is the time during which the document passes the reading point of the second document reading device 4.
The first document reading device 3 reads the document by turning on the light source from the time when the timer 1 becomes 0 until the time when the timer 3 becomes 0. The second document reading device 4 reads the document by turning on the light source from the time when the timer 2 becomes 0 until the time when the timer 4 becomes 0.

  As described above, when the original is read on one side, the reading operation speed of the image reading apparatus depends only on the scanning speed of the first original reading apparatus 3. When the original is read on both sides, the reading operation speed of the image reading apparatus depends on the smaller one of the scanning speed of the first original reading apparatus 3 and the scanning speed of the second original reading apparatus 4. In the image reading apparatus of this embodiment, the first document reading device 3 uses a CCD sensor, and the second document reading device 4 uses a CIS. The reading operation speed of the image reading apparatus 3 depends on the scanning speed of the CCD sensor of the first original reading apparatus 3 when the original is read on one side, and the reading speed of the second original reading apparatus 4 when the original is read on both sides. Depends on CIS scanning speed.

The scanning speed of the first document reading device 3 is adjusted to the scanning speed V _CCD of the CCD sensor used by the first document reading device 3 when the document reading of the image reading device is single-sided. When reading is performed on both sides, the scanning speed V _CIS of the CIS used by the second document reading device 4 is set. The CIS scanning speed V _CIS is generally relatively lower than the CCD sensor scanning speed V _CCD , and the first document reading device 3 has a scanning speed when the document reading of the image reading device is double-sided or single-sided. Smaller than

  The first document reading device 3 converts the light amount signal of the document image into an electrical signal by photoelectric conversion by the CCD image sensor 33 that receives the reflected light from the document. The light amount signal of the document image increases when the density of the document image is low and decreases when the density is high. In order to maintain the linearity of the light amount signal from the low density pixel to the high density pixel of the original image, it is necessary to keep the irradiation energy of the light applied to the original constant. Irradiation energy can be defined by the product of the amount of light indicating the intensity of light to be irradiated and the irradiation time indicating the time of light irradiation.

  The scanning speed of the first document reading device 3 is related to the irradiation time indicating the light irradiation time. When the scanning speed is high, the irradiation time is short, and when the scanning speed is low, the irradiation time is long. The scanning speed of the first document reading device 3 is smaller when the image reading device reads the document on both sides than on the one side. The irradiation time of the first document reading device 3 is longer when the image reading device reads the document on both sides than on the one side. The irradiation energy of the first document reading device 3 is greater when the amount of light applied to the document is constant when the image reading device reads the document on both sides than on the one side. When the irradiation energy is different, the light amount signal from the same density of the document image is different. In order to keep the light quantity signal from the same density of the original image constant, it can be dealt with by changing the quantity of light indicating the intensity of the irradiated light depending on whether the original of the image reading apparatus is reading on both sides or on one side.

When the CIS scanning period is T _CIS , the CIS scanning speed V _CIS is represented by s / T _CIS . s is the moving distance of CIS. When the CCD scanning period is T _CCD , the CCD scanning speed V _CCD is represented by s / T _CCD . The irradiation energy E is defined by the product of a light amount L indicating the intensity of light to be irradiated and an irradiation time T indicating the time of light irradiation. The irradiation energy E _CCD of the _CCD is defined by the product of the light amount L _CCD indicating the intensity of the irradiation light of the light source of the scanning light source unit in the first document reading device 3 and the irradiation time T _CCD indicating the light irradiation time. The When the document reading of the image reading apparatus is single-sided, the irradiation energy E _CCD of the CCD of the first document reading apparatus 3 is represented by L _CCD × T _CCD .
On the other hand, when the image reading apparatus reads the original on both sides, the moving distance of the CIS is equal to the moving distance of the CCD, so that _TCCD is represented by (V _CIS / V _CCD ) × _TCIS . When the image reading apparatus reads both sides of the original, the irradiation energy E _CCD of the CCD of the first original reading apparatus 3 is expressed by L _CCD × (V _CIS / V _CCD ) × _TCIS . When the document reading of the image reading device is double-sided, the scanning cycle of the first document reading device 3 is matched with the scanning cycle T _CIS of the _CIS , and the irradiation energy of the CCD is set so that the document reading of the image reading device is single-sided. In order to match the irradiation energy, the amount of light to be irradiated may be L _CCD × (V _CIS / V _CCD ).

In addition, the scanning speed of the first document reading device 3 is reduced from V _CCD to V _CIS when the document reading of the image reading device is double-sided than when single-sided. The irradiation time of the first document reading device is longer from _TCCD to T _CIS when the document reading of the image reading device is double-sided than when it is single-sided. The irradiation energy E _CCD of the first document reading device is greater when the image reading device reads the document on both sides than on the one side. When the irradiation energy is different, the light amount signal from the same density of the document image is different. In order to keep the light amount signal from the same density of the original image constant, the amount of light indicating the intensity of the irradiated light is changed from L _CCD to L _CCD × This can be _handled by changing to (V _CIS / V _CCD ).

According to the above, the light quantity of the CCD of the first document reading device 3 is L _CCD when the document reading of the image reading device is one side, and L _CCD × (V _CIS when the document reading of the image reading device is both sides. / V _CCD ). The amount of light L _CCD × (V _CIS / V _CCD ) of the CCD of the first document reading device when the document reading of the image reading device is double-sided is the first document when the document reading of the image reading device is single-sided. The light amount L of the CCD of the reading device is lower than that of the _CCD . The light quantity can be corrected by adjusting the light emission intensity of the light source by adjusting the current value applied to the light source.

1 is a schematic external view of a configuration showing an image reading apparatus according to an embodiment of the present invention. FIG. 2 is a schematic external view showing the overall configuration of the first document reading device. FIG. 3 is a schematic external view showing the overall configuration of the second document reading device. FIG. 3 is a schematic outline view showing the periphery of the second document reading device. FIG. 2 is a block diagram showing the overall configuration of the document reading control device, the image processing device, and the input / output interface. It is a flowchart which similarly shows the operation | movement at the time of start of embodiment. 6 is a flowchart showing an operation when reading a single side of a document. 6 is a flowchart showing an operation when reading a single side of a document. 6 is a flowchart showing an operation when reading a single side of a document. 3 is a flowchart showing an operation when reading both sides of a document. 3 is a flowchart showing an operation when reading both sides of a document. 3 is a flowchart showing an operation when reading both sides of a document. Similarly, it is a timing chart showing an operation when reading both sides of a document.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Automatic document conveying apparatus 22 Conveyance path 3 1st original reading apparatus 30a Light source 33 CCD image sensor 4 2nd original reading apparatus 40a LED
42 Line sensor unit 5 Document reading control device 6 Image processing device

Claims (8)

An original conveying means for conveying an original, a first original reading means arranged on one conveying surface side on the conveying path for conveying the original, and the first original reading means on the conveying path are arranged. A second document reading unit disposed on a conveyance surface side different from the conveyance surface side,
When reading a document image on one side of the document, one of the first document reading unit and the second document reading unit stops and stops the document transported along the transport path by a light source included therein. Read at the scanning speed when reading one side of
When reading the original images on both sides of the original, the first original reading means and the second original reading means are stopped, and the originals conveyed along the conveyance path by the light sources included in the first original reading means and the second original reading means at the same time. In an image reading device that reads at the same scanning speed,
When reading the original images on both sides of the original, the scanning speed which is smaller than the predetermined single-side reading scanning speed of the first original reading means and the predetermined single-side reading scanning speed of the second original reading means. At a speed, the first document reading unit and the second document reading unit stop and read the document images on both sides of the document at the same time, and the predetermined one-sided reading by the first document reading unit The amount of light from the light source of the first document reading unit or the second document reading unit, which has a higher scanning speed than the time scanning speed and the predetermined single-sided scanning speed of the second document reading unit, An image reading apparatus characterized by correcting the amount of light from a light source when reading an original image on one side of an original.   When reading the original images on both sides of the original, the predetermined light quantity is corrected by correcting the light quantity from the light source of the first original reading means or the second original reading means that has a higher scanning speed at the time of the one-side reading. Irradiation energy when reading the original image on one side of the original and irradiation energy when reading the original image on both sides of the original in the first original reading means or the second original reading means with the higher scanning speed during single-side reading The image reading apparatus according to claim 1, wherein: is substantially constant.   The image reading apparatus according to claim 2, wherein the irradiation energy is defined by a product of a light amount indicating the intensity of irradiated light and an irradiation time indicating a time during which the document is irradiated with light.   When reading the original images on both sides of the original, the first original reading means or the second original reading means having the higher scanning speed at the predetermined single-sided reading has the lower scanning speed at the predetermined single-sided reading. 4. The image reading apparatus according to claim 1, wherein the light emission intensity of the light source is corrected on the basis of the light source, and the light source stops and reads a document image on one side of the document.   The scanning speed V1 (mm / sec) at the time of single-sided reading of the first original reading unit and the scanning speed V2 (mm / sec) at the time of single-sided reading of the second original reading unit have a magnitude relationship of V1> V2. When reading the original images on both sides of the original, the first original reading means and the second original reading means stop at the scanning speed of V2 and read the original images on both sides of the original at the same time. By correcting the amount of light from the light source of the first document reading unit to L1 (lx) when reading a document image on one side of the document and L1 * (V2 / V1) (lx) when reading a document image on both sides of the document. In the first document reading means, the irradiation energy when reading a document image on one side of the document and the irradiation energy when reading a document image on both sides of the document are made substantially constant. The image reading apparatus according to any one of Items 1 to 4.   The image reading apparatus according to claim 1, wherein the correction of the light amount is performed by adjusting a current value applied to a light source.   Depending on when reading the original image on one side of the original and when reading the original image on both sides of the original, the change in the conveyance speed of the original in the conveyance path and the predetermined single side in the first original reading means Comparing the amount of light from the light source of the first document reading unit or the second document reading unit, which has a higher scanning speed than the scanning speed during reading and the predetermined single-sided scanning speed in the second document reading unit The image reading apparatus according to claim 1, further comprising a control unit that performs the following operations.   The control unit corrects the light amount from the light source of the first document reading unit or the second document reading unit, which has a higher scanning speed at the time of single-sided reading, when reading the document images on both sides of the document. The image reading apparatus according to claim 7, wherein:

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