JP2010178213A - Image reading apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus and an image forming apparatus that prevent occurrence of a black shadow originated in the thickness of a manuscript in the image reading apparatus that radiates light from a moving light source on the manuscript placed on a manuscript table to read images by scanning the manuscript, and to prevent occurrence of variations in light volume of each light source when a plurality of light sources are provided. <P>SOLUTION: Two light sources opposedly arranged along the moving direction and a detection portion that detects light volume of each light source are provided. A voltage or a current to be applied to the two light sources is adjusted based on detection results of the detection portion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image reading apparatus and an image forming apparatus provided with means for irradiating light from a moving light source onto a document placed on a document table and scanning the document to read an image.

  2. Description of the Related Art Conventionally, an image reading apparatus such as a scanner holds a document table on which a document is placed, a document pressing mat that presses and closes the document placed on the document table, and holds the document pressing mat. An original holding plate for preventing the original holding mat from being lifted is provided. The document pressing mat includes a rectangular white resin sheet, and an elastic member that is interposed between the white sheet and the document pressing plate and follows the white sheet. The document pressing plate is attached to be freely opened and closed.

  In the conventional image reading apparatus having such a configuration, the document is placed on the document table, the document pressing plate is closed, and the document is mated to the document table with the document pressing mat. The light from the light source was irradiated from below the document table toward the document, and the document was scanned to read the image of the document.

  FIG. 13 is an explanatory diagram for explaining a problem in the conventional image reading apparatus. In the figure, white arrows indicate light paths. In a conventional image reading apparatus, for example, a rectangular document P is placed on the left side of the document table 130, and scanning is performed while the light source L moves from the left side to the right side of the document table 130. When the original P to be read is thin, the original P is brought into close contact with the original table 130 with almost no gap between the edge of the original P and the sheet S, so that the image data of the read image is displayed. Good prints can also be obtained in printing based on this.

  On the other hand, when the original P to be read is thick, such as drawing paper, a postcard, and a business card, the edge of the right end of the original P and the sheet are caused by the thickness of the original P, as shown in FIG. A step (G) occurs between S and S. Therefore, when the light source L is positioned below the right end portion of the document P, a black shadow is generated near the edge of the document P. When printing is performed based on the image data of the image read in this state, there is a problem that the shadow appears on the printed matter.

  FIG. 14 is a cross-sectional view showing a longitudinal section of an image reading apparatus that prevents black shadows from occurring due to the thickness of the document. In the figure, the arrows indicate the light paths. The image reading apparatus includes a light source L that irradiates light on a document placed on the document table 130 from below the document table 130, and the reflected light reflected by the document or the document table 130 is again applied to the document. A reflecting plate R that reflects toward the light source L is provided on the right side of the light source L across the space, and the light amount ratio between the light source L and the reflecting plate R is 4: 6.

  Therefore, as described above, when the original is placed in the back left of the original table 130 and scanning is performed while the light source L is moving from the left side to the right side of the original table 130, the right end portion of the original plate. Even if the light source L is positioned below, the light from the reflecting plate R irradiates the vicinity of the edge of the right end portion of the document, so that it is possible to prevent a shadow from being generated near the edge of the right end portion of the document.

  Further, in Patent Document 1, a plurality of light sources are provided, the plurality of light sources are individually turned on, the amount of light of each light source is measured, and it is determined whether or not each light source has reached the end of its life. A possible image reading apparatus is disclosed.

JP 2000-39679 A

  However, the conventional image reading apparatus as described above cannot cope with the deterioration of the light source as the usage time elapses. In other words, the light quantity ratio cannot be maintained due to the deterioration of the light source as the usage time elapses, and there is a possibility that a black shadow due to the thickness of the document may occur.

  In addition, since the image reading apparatus of Patent Document 1 includes a plurality of light sources, the light sources deteriorate as the usage time elapses, and there is a possibility that the light amounts of the respective light sources may vary.

  The present invention has been made in view of such circumstances, and an object of the present invention is to irradiate a document placed on a document table with light from a moving light source and scan the document to obtain an image. An image reading apparatus including a reading unit includes two light sources disposed to face each other in a moving direction thereof, and a detection unit that detects a light amount of each light source, and the two light sources based on a detection result of the detection unit By adjusting the voltage or current applied to the light source, it is possible to prevent black shadows from occurring due to the thickness of the document due to deterioration of the light source, and in the case where a plurality of light sources are provided, the light quantity of each light source It is an object of the present invention to provide an image reading apparatus and an image forming apparatus that can prevent the occurrence of variations.

  An image reading apparatus according to the present invention is an image reading apparatus provided with means for irradiating light from a moving light source to a document placed on a document table and scanning the document to read an image. Two arranged light sources, a detection unit for detecting the light quantity of each light source, and an adjusting unit for adjusting a voltage or a current applied to the two light sources based on a detection result of the detection unit are provided. It is characterized by that.

  In the present invention, the detection unit detects the amount of light of each of the two light sources. The adjustment means adjusts the voltage or current applied to the two light sources so that the light amounts of the two light sources are equal based on the detection result of the detection unit, and the light amounts of the two light sources vary. To prevent. Further, the adjustment means adjusts the voltage or current applied to the two light sources based on the detection result of the detection unit so that the light amounts of the two light sources have a predetermined light amount ratio. To prevent shadows from appearing.

  In the image reading apparatus according to the present invention, the document table is rectangular, and the scanning is performed from one end side of the document table toward the other end side facing the one end side, and receives a predetermined instruction from the outside. A receiving unit, and when the receiving unit receives the instruction, the adjusting unit applies a voltage or a current to be applied to a light source on the other end side of the document table among the two light sources from a light source on one end side. It is characterized by being configured to be adjusted higher.

  In the present invention, when the accepting unit accepts the instruction, the adjusting unit applies a voltage or a current applied to the light source on the other end side of the document table among the two light sources on one end side. Since the light quantity of the light source on the other end side is increased by adjusting higher than the light source, for example, when scanning with a thick original placed on one end side of the original table, the other end of the original table is scanned. It is possible to prevent a shadow from being generated near the edge of the original on the side.

  The image reading apparatus according to the present invention includes position detection means for detecting positions of the two light sources with respect to the original, and the adjustment means determines whether the voltage applied to the two light sources or the voltage based on the detection result of the position detection means. It is configured to adjust the current.

  In the present invention, for example, when the position detection unit detects that the two light sources are located near the center of the document, the adjustment unit causes the light amounts of the two light sources to be equal. In addition, the voltage or current applied to each light source is adjusted. When the position detection unit detects that the two light sources are located near one edge of the document, the adjustment unit determines the light amount of the light source near the one edge among the two light sources. The voltage or current applied to each light source is adjusted so as to be high.

  The image reading apparatus according to the present invention includes a receiving unit that receives a predetermined instruction from the outside. When the receiving unit receives the instruction, the adjusting unit is configured to perform the two operations based on the detection result of the position detecting unit. The voltage or current applied to the light source is changed, respectively.

  In the present invention, when the receiving unit receives the instruction, the adjusting unit changes the voltage or current applied to the two light sources based on the detection result of the position detecting unit, and the 2 The light amounts of the two light sources are appropriately adjusted according to the positions of the two light sources with respect to the document.

  The image reading apparatus according to the present invention is characterized in that the light source includes an LED, a halogen lamp, and / or a xenon lamp.

  In the present invention, the light source includes, for example, a plurality of LEDs arranged in parallel in a direction crossing the moving direction, or a halogen lamp or a xenon lamp extending in the direction.

  An image forming apparatus according to the present invention includes any one of the image reading devices described above, and is configured to form an image on a sheet based on image data of an image read by the image reading device. It is characterized by being.

  In the present invention, an image is read by the image reading device, and an image is formed on a sheet based on the image data of the image.

  According to the present invention, the light source includes two light sources arranged opposite to each other in the moving direction, and a detection unit that detects the light amount of each light source, and applies to the two light sources based on the detection result of the detection unit. Since the voltage or current is adjusted, it is possible to prevent the occurrence of black shadows due to the thickness of the original with the deterioration of the light source, and in the case where a plurality of light sources are provided, the amount of light of each light source varies. Can be prevented.

1 is a schematic longitudinal sectional view of a digital multi-function peripheral according to Embodiment 1 of the present invention. 1 is a block diagram illustrating a main configuration of an image reading device of a digital multifunction peripheral according to a first embodiment of the present invention. It is a schematic diagram which shows typically the structure of the reading unit of an image reading apparatus. 1 is a perspective view showing a light source unit of a digital multi-function peripheral according to Embodiment 1 of the present invention. It is a schematic diagram which illustrates typically the structure of the light source unit of the digital multifunctional device which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view of the light source unit of the digital multi-functional peripheral according to the first embodiment of the present invention. FIG. 5 is an explanatory diagram for explaining document detection by a document detection unit of the digital multi-function peripheral according to Embodiment 1 of the present invention. It is a figure which shows the operation panel and display part of a digital multi-function peripheral which concern on Embodiment 1 of this invention. 6 is an explanatory diagram for explaining a reception screen in the digital multi-function peripheral according to Embodiment 1 of the present invention. FIG. 4 is a flowchart showing processing of a CPU of the digital multi-function peripheral according to Embodiment 1 of the present invention. FIG. 6 is an explanatory diagram for explaining an irradiation state when the first light source and the second light source are located below the right end portion of the document in the digital multi-functional peripheral according to the first embodiment of the present invention. 6 is a flowchart illustrating processing of a CPU of a digital multi-function peripheral according to Embodiment 2 of the present invention. It is explanatory drawing for demonstrating the problem in the conventional image reading apparatus. FIG. 3 is a cross-sectional view illustrating a vertical cross section of an image reading apparatus that prevents black shadows from occurring due to the thickness of a document.

  Hereinafter, an embodiment in which an image reading apparatus and an image forming apparatus according to the present invention are applied to a digital multi-function peripheral having a copy function, a print function, and the like will be specifically described with reference to the drawings. For convenience of explanation, a case where the light amount of the light source is adjusted by controlling the applied voltage will be described as an example.

(Embodiment 1)
FIG. 1 is a schematic longitudinal sectional view of a digital multifunction peripheral according to Embodiment 1 of the present invention.

  The digital multi-function peripheral according to the present invention includes an apparatus main body 200 and an image reading apparatus 100 provided on the upper part of the apparatus main body 200.

  The apparatus main body 200 includes an exposure unit 1, a developing device 2, a photosensitive drum 3, a cleaner unit 4, a charger 5, an intermediate transfer belt unit 6, a fixing unit 7, a paper feed cassette 81, a paper discharge tray 91, and the like. It is configured.

  The image data handled in the digital multifunction peripheral according to the present invention is, for example, in accordance with a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Accordingly, four developing devices 2, photosensitive drums 3, chargers 5, and cleaner units 4 are provided so as to form four types of latent images corresponding to the respective colors. Black, cyan, magenta, and yellow are respectively provided. These are set to form four image stations.

  The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 with a predetermined potential.

  The exposure unit 1 is configured as a laser scanning unit (LSU) provided with a laser emitting portion, a reflection mirror, and the like. The exposure unit 1 includes a polygon mirror that scans a laser beam, and optical elements such as a lens and a mirror for guiding the laser beam reflected by the polygon mirror to the photosensitive drum 3. In addition, as the exposure unit 1, for example, a method using an EL and LED writing head in which light emitting elements are arranged in an array can be employed.

  The exposure unit 1 has a function of forming an electrostatic latent image corresponding to the image data on the surface thereof by exposing the charged photosensitive drum 3 according to the input image data. The developing device 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toner of four colors (YMCK). The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The intermediate transfer belt unit 6 disposed above the photosensitive drum 3 includes an intermediate transfer belt 61, an intermediate transfer belt driving roller 62, an intermediate transfer belt driven roller 63, an intermediate transfer roller 64, and an intermediate transfer belt cleaning unit 65. I have. Four intermediate transfer rollers 64 are provided corresponding to each color for YMCK.

  The intermediate transfer belt driving roller 62, the intermediate transfer belt driven roller 63, and the intermediate transfer roller 64 are driven to rotate while the intermediate transfer belt 61 is stretched. Each intermediate transfer roller 64 provides a transfer bias for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 61. The intermediate transfer belt 61 is provided in contact with each photosensitive drum 3. A function of forming a color toner image (multicolor toner image) on the intermediate transfer belt 61 by sequentially superimposing and transferring the toner images of the respective colors formed on the photosensitive drum 3 onto the intermediate transfer belt 61. have. The intermediate transfer belt 61 is formed in an endless shape using, for example, a film having a thickness of about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 61 is performed by an intermediate transfer roller 64 that is in contact with the back side of the intermediate transfer belt 61. A high-voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 64 in order to transfer the toner image. The intermediate transfer roller 64 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 61. In Embodiment 1, a roller shape is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the electrostatic images visualized according to the respective hues on the respective photosensitive drums 3 are laminated on the intermediate transfer belt 61. As described above, the laminated image information is transferred onto the sheet by the transfer roller 10 disposed at a contact position between the sheet and the intermediate transfer belt 61 described later by the rotation of the intermediate transfer belt 61. At this time, the intermediate transfer belt 61 and the transfer roller 10 are pressed against each other at a predetermined nip, and a voltage for transferring the toner onto the sheet is applied to the transfer roller 10 (the polarity opposite to the toner charging polarity (−)). (+) High voltage). Further, in order to obtain the nip constantly, the transfer roller 10 uses either the transfer roller 10 or the intermediate transfer belt drive roller 62 as a hard material (metal or the like) and the other as a soft material such as an elastic roller (elastic rubber roller). Or a foaming resin roller or the like).

  Further, the toner adhering to the intermediate transfer belt 61 due to contact with the photosensitive drum 3 or the toner remaining on the intermediate transfer belt 61 without being transferred onto the sheet by the transfer roller 10 will be mixed in the next step. In order to cause this to occur, the intermediate transfer belt cleaning unit 65 is set to be removed and collected. The intermediate transfer belt cleaning unit 65 includes a cleaning blade as a cleaning member that comes into contact with the intermediate transfer belt 61. The intermediate transfer belt 61 that comes into contact with the cleaning blade is supported by an intermediate transfer belt driven roller 63 from the back side. ing.

The fixing unit 7 includes a heat roller and a pressure roller. The fixing unit 7 is rotated by sandwiching the sheet on which the toner image is transferred by these two rollers, and the toner image is heated and fixed on the sheet by the heat of the heat roller.

  The paper feed cassette 81 is a tray for storing sheets (recording paper) used for image formation, and is provided below the exposure unit 1 of the apparatus main body 200. A sheet used for image formation can also be placed in the manual paper feed cassette 82. A paper discharge tray 91 provided above the apparatus main body 200 collects printed sheets face down.

  Further, the apparatus main body 200 has a substantially vertical sheet conveyance path S for feeding the sheets of the sheet feeding cassette 81 and the manual sheet feeding cassette 82 to the sheet discharge tray 91 via the transfer roller 10 and the fixing unit 7. Is provided. In the vicinity of the paper transport path S from the paper feed cassette 81 or the manual paper feed cassette 82 to the paper discharge tray 91, pickup rollers 11a and 11b, a plurality of transport rollers 12a, 12b, 12c and 12d, a registration roller 13, and a transfer roller 10, a fixing unit 7 and the like are arranged. The conveyance rollers 12 a, 12 b, 12 c, and 12 d are small rollers for promoting and assisting the conveyance of the sheet, and a plurality of conveyance rollers 12 a, 12 b, 12 c, and 12 d are provided along the sheet conveyance path S. The pickup roller 11 a is provided near the end of the paper feed cassette 81, picks up sheets one by one from the paper feed cassette 81, and supplies them to the paper transport path S. Similarly, the pickup roller 11 b is provided near the end of the manual paper feed cassette 82, picks up sheets one by one from the manual paper feed cassette 82, and supplies the sheets to the paper transport path S.

  The image reading apparatus 100 includes a document placing table 130 made of rectangular transparent glass on which a document is placed, and a document feeding device 120 that sends the document to the document placing table 130 is provided above the document placing table 130. Yes. The document feeder 120 is mounted so as to be rotatable in the direction of arrow N in FIG. 1, and is configured so that a document can be placed manually by opening the document table 130. The image reading apparatus 100 includes a reading unit 140 that reads an image of a document on the document table 130.

  FIG. 2 is a block diagram illustrating a main part configuration of the image reading apparatus 100 of the digital multi-function peripheral according to the first embodiment of the present invention. FIG. 3 is a schematic diagram schematically illustrating the configuration of the reading unit 140 of the image reading apparatus 100. FIG. In FIG. 3, the light path is indicated by a white arrow.

  The image reading apparatus 100 of the digital multifunction peripheral according to the first embodiment of the present invention includes a control device 101, a document reading control unit 102, a scanning motor driving unit 103, a scanning motor 104, a light amount control unit 105, and a first pair of light sources. A light source 141A, a second light source 141B, a document detection unit 106, and a storage unit 107 are provided. In addition, the image reading apparatus 100 includes an operation panel 108 having a display unit 109 in front of the document placing table 130.

  The reading unit 140 includes a light source unit 141, a mirror unit 142, an imaging lens 143, a CCD 144 (detection unit), and the like for reading an image recorded on the surface of the document P. The light source unit 141 and the mirror unit 142 constitute a scanning unit (not shown) that moves in the sub-scanning direction (indicated by a white arrow in the drawing) when scanning the document P.

  The control device 101 includes a CPU 101A and a ROM 101B. The CPU 101A controls the various hardware described above. Further, the CPU 101A determines whether or not the light amounts of the first light source 141A and the second light source 141B are equal, and calculates a voltage value to be applied to the first light source 141A and the second light source 141B. The ROM 101B stores a control program for controlling each hardware described above, a program for displaying a reception screen described later, and the like.

  The document reading control unit 102 controls the movement of the scanning unit by controlling the scanning motor driving unit 103 in accordance with an instruction from the CPU 101A.

  The scanning motor driving unit 103 drives the scanning motor 104 such as a stepping motor, for example, in accordance with a signal from the document reading control unit 102, and moves the scanning unit.

  The document reading control unit 102 controls the operation of the scanning motor driving unit 103 based on an instruction from the CPU 101 </ b> A of the control device 101. That is, when the document reading control unit 102 receives an instruction for executing reading from the CPU 101A, the document reading control unit 102 outputs a driving start signal to the scanning motor driving unit 103, and the scanning motor driving unit 103 responds to the driving start signal with the scanning unit. A driving voltage is applied to the scanning motor 104 which is a driving source of the moving operation. As a result, the scanning motor 104 rotates and the scanning unit reciprocates in the sub-scanning direction.

  The light quantity control unit 105 includes two circuits that apply voltages to the first light source 141A and the second light source 141B in response to an instruction from the CPU 101A based on the detection result of the light quantity by the CCD 144, and the two circuits are provided via the two circuits. By adjusting the applied voltage, the light amounts of the first light source 141A and the second light source 141B are controlled.

  The first light source 141A and the second light source 141B are arranged to face each other in the sub-scanning direction (or the moving direction of the scanning unit). The first light source 141A includes a plurality of LEDs 145, 145, 145,... On a strip-shaped substrate 147 extending in the main scanning direction intersecting with the sub-scanning direction. ) Along the line. Note that the second light source 141B has a plurality of LEDs 146, 146, and 146 on a substrate 148 provided at an appropriate interval in the right direction of the substrate 147 of the first light source 141A, like the first light source 141A. Are arranged along the longitudinal direction of the substrate 148. In Embodiment 1, a case where an LED is used as a light source will be described as an example, but the present invention is not limited to this. For example, a configuration in which a rod-like fluorescent lamp, a halogen lamp, a xenon lamp or the like extending along the main scanning direction is attached may be used.

  Hereinafter, the configuration of the light source unit 141 including the first light source 141A and the second light source 141B will be described. 4 is a perspective view showing the light source unit 141 of the digital multi-function peripheral according to Embodiment 1 of the present invention, FIG. 5 is a schematic diagram schematically explaining the configuration of the light source unit 141, and FIG. 6 is a longitudinal section of the light source unit 141. FIG. In FIG. 6, the light path is indicated by arrows.

  The substrate 147 of the first light source 141A and the substrate 148 of the second light source 141B are attached obliquely with respect to the document table 130, and a plurality of LEDs 145, 145, 145,... And a plurality of LEDs 146, 146, 146, respectively. … Is implemented. The LED 145 and the LED 146 are so-called side-emitting LEDs that emit light from the side surface of the cubic LED. The LED 145 and the LED 146 emit light from the side surfaces facing each other, and irradiate the document P placed on the document table 130. To do.

  The first light source 141A and the second light source 141B are attached so as to face each other with an appropriate interval, and the reflected light reflected by the document P is between the first light source 141A and the second light source 141B. A passing slit 149 is provided. A first mirror 141 </ b> C that guides the reflected light to the mirror unit 142 is provided obliquely with respect to the document placement table 130 immediately below the slit 149. The reflected light passes through the slit 149, is reflected by the first mirror 141C, and enters the mirror unit 142.

  The mirror unit 142 includes a second mirror 142A and a third mirror 142B, and the light incident on the mirror unit 142 is further reflected by the second mirror 142A and the third mirror 142B and guided to the lens 143.

  The reflected light entering the lens 143 is collected by the lens 143 and enters the CCD 144. The CCD 144 is an image sensor that forms an image in response to incident reflected light, and includes several thousand photocells. Each photocell performs photoelectric conversion and converts the incident light into an analog electrical signal corresponding to the amount of light. Convert and output. The analog electrical signal from the CCD 144 is then A / D converted.

  The document detection unit 106 detects the position and size of the document P placed on the document placement table 130. FIG. 7 is an explanatory diagram for explaining document detection by the document detection unit 106. The digital multifunction peripheral according to Embodiment 1 of the present invention is provided with three optical sensors 131, 132, and 133 below the document table 130. Each of the optical sensors 131, 132, and 133 includes a light emitting element S1 and a light receiving element R1, a light emitting element S2 and a light receiving element R2, a light emitting element S3, and a light receiving element R3, and is appropriately disposed below the document table 130. If the light emitting elements S1, S2, and S3 of the optical sensors 131, 132, and 133 emit light toward the document placing table 130, and the document is placed on the document placing table 130, the light is reflected by the document and the light receiving element R1. , R2 and R3 receive the reflected light, so that the presence of the document can be detected. On the other hand, if there is no document on the document table 130, the light from the light emitting elements S1, S2, and S3 is not reflected by the document, so that the light receiving elements R1, R2, and R3 cannot receive the reflected light, and the presence of the document is detected. Can not. For example, when the light receiving elements R1, R2, and R3 also receive light, the document detection unit 106 detects that the document placed on the document placement table 130 is A3 size. Accordingly, when a document of a standard size (for example, A3, A4, A4R, B4, B5, etc.) is placed on the left side of the document placement table 130, the position and size of the document can be detected.

  On the other hand, if the document placed on the document placement table 130 is not a standard size, or if the document is not placed on the back left of the document placement table 130, pre-scanning is performed before reading the document. Then, the size and position of the document are detected from the pixels at the edge of the document in the main scanning direction and the sub-scanning direction of the document imaged on the CCD 144.

  The moving position of the scanning unit can be detected from the pulse of the scanning motor 104 that drives the scanning units (the first light source 141A and the second light source 141B), so that the edge of the document placed on the document placement table 130 can be detected. When the scanning unit (the first light source 141A and the second light source 141B) is positioned below, the light amounts of the first light source 141A and the second light source 141B can be adjusted as will be described later. Further, the present invention is not limited to this, and the time until the scanning unit moves below the edge of the document placed on the document placement table 130 by measuring the time from the start of scanning (reading) of the scanning unit. You may comprise so that time may be calculated and the light quantity of 1st light source 141A and 2nd light source 141B may be adjusted so that it may mention later.

  The storage unit 107 converts the light amounts of the first light source 141A and the second light source 141B detected by the CCD 144 into digital signals, and stores data relating to such digital values. The storage unit 107 stores data related to the position of the document on the document table 130 detected by the document detection unit 106.

  The operation panel 108 includes a display unit 109 and receives an instruction from a user operation. FIG. 8 shows the operation panel 108 and the display unit 109. The operation panel 108 includes an input unit 108A including various input keys such as a numeric keypad, a start key, and a clear key, and a display unit 109 such as a liquid crystal display, and inputs instructions for operating the entire apparatus, various settings, and the like. The input content and the operation status of the entire apparatus are displayed via the display unit 109. Note that the display unit 109 is provided with a touch panel so that an input operation can be performed via the touch panel.

  The display unit 109 has a reception screen T (reception unit) that receives a selection (predetermined instruction) from the user as to whether the original to be read is thick paper such as postcards and paper, a book, or plain paper. Is displayed. FIG. 9 is an explanatory diagram for explaining the reception screen T. The reception screen T is provided with “plain paper” and “thick paper or book” soft keys. For example, the user can perform the selection by pressing one of the soft keys with a fingertip. The CPU 101A accepts the selection instruction via the display unit 109 and performs appropriate processing.

Hereinafter, detection and adjustment of the light amounts of the first light source 141A and the second light source 141B in the digital multi-function peripheral according to Embodiment 1 of the present invention will be described.
The first light source 141A and the second light source 141B are arranged at positions where exposure is possible by the first light source 141A and the second light source 141B, and a shading sheet (or white reference plate) for acquiring reference data for shading correction is used. The CCD 144 receives the reflected light and receives the reflected light via the mirror unit 142. The CCD 144 converts the reflected light into an analog electric signal corresponding to the amount of light, and outputs the analog electric signal. The analog electric signal is A / D converted, for example, converted into an 8-bit (0 to 255 gradation) digital electric signal. . A digital value related to the digital electric signal is stored in the storage unit 107.

  For example, the digital value of the amount of light related to the reflected light when the first light source 141A irradiates the shading sheet is 250, and the digital value of the amount of light related to the reflected light when the second light source 141B irradiates the shading sheet is 240. In some cases, these digital values are stored in the storage unit 107. In such a case, the light amounts of the first light source 141A and the second light source 141B vary.

  At this time, when the light amount ratio of the first light source 141A and the second light source 141B is set to 1: 1 and the variation in the light amount is eliminated, the light amount control unit 105 is based on the digital value stored in the storage unit 107, for example, The voltage applied to the second light source 141B is multiplied by “250/240” with respect to the one light source 141A.

  When the light amount ratio between the first light source 141A and the second light source 141B is set to 4: 6, for example, the light amount control unit 105 is based on the digital value stored in the storage unit 107, for example, based on the first light source 141A. Thus, the voltage applied to the second light source 141B is multiplied by “250/240 × 6/4”.

  Hereinafter, reading processing by the digital multi-function peripheral according to Embodiment 1 of the present invention will be described. FIG. 10 is a flowchart showing processing of the CPU 101A of the digital multi-function peripheral according to Embodiment 1 of the present invention. For convenience of explanation, the first light source 141 </ b> A and the second light source 141 </ b> B move back and forth from the left side to the right side of the document placing table 130 and back and forth from the right side to the left side of the document placing table 130. At this time, the document placed on the document placing table 130 is scanned, and the left to right direction of the document placing table 130 is set as the sub-scanning direction, and the direction crossing the sub-scanning direction is set as the main scanning direction. It is assumed that a rectangular document is placed on the left side of the document placing table 130 and the document is read in accordance with an instruction from the user.

  The user places a document on the left side of the document placing table 130 and operates the operation panel 108 to instruct reading of the document. The CPU 101A accepts a document reading instruction from the user via the operation panel 108 (step S101).

  The CPU 101A detects the light amounts of the first light source 141A and the second light source 141B in response to a document reading instruction from the user (step S102). The amount of light is detected by the CCD 144 receiving reflected light when the first light source 141A and the second light source 141B separately irradiate the shading sheet, and converting the reflected light into an analog electrical signal corresponding to the amount of light. Done. Detailed description is as described above, and will be omitted. The detected light amount is stored in the storage unit 107.

  Next, the CPU 101A displays a reception screen T on the display unit 109 using a program for displaying the reception screen T stored in the ROM 101B (step S103). The acceptance screen T is provided with two soft keys “plain paper” and “thick paper or book”, and the CPU 101A accepts a selection instruction by selecting and pressing one of them.

  The CPU 101A determines whether or not an instruction to select “thick paper or book” has been received by monitoring the touch panel of the display unit 109 (step S104).

  If the CPU 101A determines that an instruction to select “thick paper or book” has been received (step S104: YES), the CPU 101A sets the light amounts of the first light source 141A and the second light source 141B to a predetermined ratio (eg, 4: 6). The voltage value to be applied to each of the first light source 141A and the second light source 141B is calculated (step S105). This is performed based on the light amounts of the first light source 141A and the second light source 141B stored in the storage unit 107, and the detailed description thereof has been described above and is omitted.

  Based on the calculated voltage value, the CPU 101A adjusts the voltage to be applied to each of the first light source 141A and the second light source 141B (step S106). This is performed by the CPU 101A instructing the light amount control unit 105 to apply a voltage to the first light source 141A and the second light source 141B based on the voltage value calculated in step S105.

  Next, the CPU 101A instructs the document reading control unit 102 to start reading (step S107). The document reading control unit 102 outputs a driving start signal to the scanning motor driving unit 103 in response to a reading execution instruction from the CPU 101A, and the scanning motor driving unit 103 applies a driving voltage to the scanning motor 104 in response to the driving start signal. This is applied to drive the scanning unit, and scanning (reading) is started. At this time, the first light source 141 </ b> A and the second light source 141 </ b> B irradiate the document placed on the document placement table 130 while maintaining a light quantity ratio of 4: 6. Therefore, when the original is thick, it is possible to prevent black shadows from occurring near the right edge of the original due to the thickness of the original. This will be described in detail below.

  FIG. 11 is an explanatory diagram for explaining an irradiation situation when the first light source 141A and the second light source 141B are located below the right end portion of the document. For convenience of explanation, the sub-scanning direction in the figure is the left-right direction.

  The document feeder 120 holds a deformable document pressing mat 120A that presses and closely contacts the document P placed on the document table 130, and the document pressing mat 120A. The document pressing mat 120A is lifted by the document P. A document holding plate 120B is provided. When the original P is read with the thick original P placed on the left side (A side in the sub-scanning direction in FIG. 11) of the original placement table 130, the right end of the original P depends on the thickness of the original P. A step (G) is generated between the edge of the document and the original presser mat 120A. In such a case, the shadow from the step (G) is generated by the light from the first light source 141A (left side in the figure). However, since the light from the second light source 141B provided at an appropriate distance from the first light source 141A in the right direction is irradiated toward the step (G), it is prevented that a shadow is generated by illuminating the step (G). it can.

  On the other hand, when the CPU 101A determines in step S104 that the instruction to select “thick paper or book” has not been received (step S104: NO), the first light source 141A and the second light source 141B stored in the storage unit 107 are determined. Based on the light amount, it is determined whether or not the light amounts of the first light source 141A and the second light source 141B are equal (step S108).

  When the CPU 101A determines that the light amounts of the first light source 141A and the second light source 141B are not equal (step S108: NO), in order to make the light amounts of the first light source 141A and the second light source 141B equal by the above-described method, A voltage value to be applied to each of the first light source 141A and the second light source 141B is calculated (step S109).

  Next, the CPU 101A adjusts the voltage to be applied to each of the first light source 141A and the second light source 141B based on the calculated voltage value (step S110).

  CPU 101A instructs document reading control unit 102 to start reading (step S111). At this time, the first light source 141A and the second light source 141B irradiate the document placed on the document placement table 130 while maintaining a light quantity ratio of 1: 1. Accordingly, it is possible to prevent variation in the light amount of each light source due to deterioration of the light source.

  On the other hand, when CPU 101A determines in step S108 that the light amounts of first light source 141A and second light source 141B are equal (step S108: YES), the process proceeds to step S111.

(Embodiment 2)
FIG. 12 is a flowchart showing processing of the CPU 101A of the digital multi-function peripheral according to Embodiment 2 of the present invention. For convenience of explanation, the first light source 141 </ b> A and the second light source 141 </ b> B move back and forth from the left side to the right side of the document placing table 130 and back and forth from the right side to the left side of the document placing table 130. At this time, the document placed on the document placing table 130 is scanned, and the left to right direction of the document placing table 130 is set as the sub-scanning direction, and the direction crossing the sub-scanning direction is set as the main scanning direction. It is assumed that a rectangular document is placed on the left side of the document placing table 130 and the document is read in accordance with an instruction from the user.

  The user places a document on the left side of the document placing table 130 and operates the operation panel 108 to instruct reading of the document. The CPU 101A accepts a document reading instruction from the user via the operation panel 108 (step S201).

  The CPU 101A detects the light amounts of the first light source 141A and the second light source 141B in response to a document reading instruction from the user (step S202). The amount of light is detected by the CCD 144 receiving reflected light when the first light source 141A and the second light source 141B separately irradiate the shading sheet, and converting the reflected light into an analog electrical signal corresponding to the amount of light. Done. The detected light amount is stored in the storage unit 107.

  Next, the CPU 101A instructs the document detection unit 106 to detect the position of the document (step S203). In response to the CPU 101A, the document detection unit 106 detects the position (size) of the document based on the detection results of the optical sensors 131, 132, and 133. Hereinafter, for convenience of explanation, it is assumed that the document is A4 size.

  Next, the CPU 101A displays the reception screen T on the display unit 109 using a program for displaying the reception screen T stored in the ROM 101B (step S204). The acceptance screen T is provided with two soft keys “plain paper” and “thick paper or book”, and the CPU 101A accepts a selection instruction by selecting and pressing one of them.

  The CPU 101A determines whether or not an instruction to select “thick paper or book” has been received by monitoring the touch panel of the display unit 109 (step S205).

  When the CPU 101A determines that an instruction to select “thick paper or book” has been received (step S205: YES), the first light source 141A and the second light source 141B are set to 1: 1 and 4: 6 in order to change the light amounts of the first light source 141A and the second light source 141B. Voltage values to be applied to the light source 141A and the second light source 141B are calculated (step S206). This is performed based on the light amounts of the first light source 141A and the second light source 141B stored in the storage unit 107, and the detailed description thereof has been described above and is omitted.

  The CPU 101A should apply to each of the first light source 141A and the second light source 141B based on the voltage value for setting the light amount of the first light source 141A and the second light source 141B to 1: 1 among the calculated voltage values. The voltage is adjusted (step S207). This is performed by the CPU 101A instructing the light amount control unit 105 to apply a voltage to the first light source 141A and the second light source 141B based on the voltage value calculated in step S206.

  Next, the CPU 101A instructs the document reading control unit 102 to start reading (step S208). The document reading control unit 102 outputs a driving start signal to the scanning motor driving unit 103 in response to a reading execution instruction from the CPU 101A, and the scanning motor driving unit 103 applies a driving voltage to the scanning motor 104 in response to the driving start signal. This is applied to drive the scanning unit, and scanning (reading) is started. At this time, the first light source 141A and the second light source 141B irradiate the document placed on the document placement table 130 while maintaining a light quantity ratio of 1: 1.

  Thereafter, the CPU 101A detects the position of the scanning unit (first light source 141A and second light source 141B) with respect to the document (step S209), and the scanning unit (first light source 141A and second light source 141B) is the document placement table. It is determined whether or not the document is placed below the right end of the document placed on 130 (step S210). As described above, the moving position of the scanning unit can be detected from the pulse of the scanning motor 104 that drives the scanning unit, and since the document is already detected in step S203, it is detected that the document is A4 size. Based on this, the CPU 101A can detect the position of the scanning unit (the first light source 141A and the second light source 141B) and determine whether or not it is located below the right end portion of the document placed on the document placement table 130. .

  If the CPU 101A determines that the first light source 141A and the second light source 141B are not located below the right end portion of the document placed on the document placement table 130 (step S210: NO), the first light source 141A and the first light source 141A It waits until the two light sources 141B are positioned below the right end of the document placed on the document placement table 130.

  On the other hand, when the CPU 101A determines that the first light source 141A and the second light source 141B are located below the right end portion of the document placed on the document placement table 130 (step S210: YES), the first light source 141A. And based on the voltage value for making the light quantity of the 2nd light source 141B 4: 6, the voltage which should be applied to each of the 1st light source 141A and the 2nd light source 141B is adjusted (step S211).

  Accordingly, the first light source 141 </ b> A and the second light source 141 </ b> B irradiate the document placed on the document placement table 130 in a state where the light amount ratio of 1: 1 is changed to the light amount ratio of 4: 6. Therefore, when the original is thick, it is possible to prevent black shadows from occurring near the right edge of the original due to the thickness of the original.

  On the other hand, if the CPU 101A determines in step S205 that the instruction to select “thick paper or book” has not been received (step S205: NO), the first light source 141A and the second light source 141B stored in the storage unit 107 are determined. Based on the light amount, it is determined whether the light amounts of the first light source 141A and the second light source 141B are equal (step S212).

  When the CPU 101A determines that the light amounts of the first light source 141A and the second light source 141B are not equal (step S212: NO), in order to make the light amounts of the first light source 141A and the second light source 141B equal by the above-described method, Voltage values to be applied to the first light source 141A and the second light source 141B are calculated (step S213).

  Next, the CPU 101A adjusts the voltage to be applied to each of the first light source 141A and the second light source 141B based on the calculated voltage value (step S214).

  CPU 101A instructs document reading control unit 102 to start reading (step S215). At this time, the first light source 141A and the second light source 141B irradiate the document placed on the document placement table 130 while maintaining a light quantity ratio of 1: 1.

  On the other hand, when the CPU 101A determines in step S212 that the light amounts of the first light source 141A and the second light source 141B are equal (step S212: YES), the process proceeds to step S215.

  In the second embodiment, a case where a rectangular document is placed on the left side of the document placing table 130 has been described as an example. However, the present invention is not limited to this. For example, the effect of the present invention can be achieved even when a document is placed at a predetermined interval from the left back of the document placement table 130. In such a case, the light quantity ratios of the first light source 141A and the second light source 141B may be changed on the left and right ends of the document based on the result of the document position detection by prescan.

  Specifically, when the first light source 141A and the second light source 141B are located below the left end portion of the document, the light amount of the first light source 141A is higher than that of the second light source 141B (for example, 6: 4). Irradiation is performed toward a step formed between the edge of the left end portion of the original and the original presser mat 120A depending on the thickness of the original. Further, when the first light source 141A and the second light source 141B are positioned below the left end portion and the right end portion of the original, the light amounts of the first light source 141A and the second light source 141B are made equal. When the first light source 141A and the second light source 141B are located below the right edge of the document, the light amount of the second light source 141B is higher than that of the first light source 141A (for example, 4: 6), and the above. What is necessary is just to comprise so that it may irradiate toward the level | step difference which arises between the edge of the right end part of this original, and the original presser mat 120A according to the thickness of the original.

  In the above description, the case where the applied voltage is adjusted when the first light source 141A and the second light source 141B are positioned below the right end portion of the document placed on the document placement table 130 has been described as an example. However, in practice, it is desirable to adjust the applied voltage several milliseconds before the first light source 141A and the second light source 141B are positioned below the right end of the document placed on the document placement table 130. .

  In the above description, the case where the light amount of the light source is adjusted by controlling the applied voltage has been described as an example. However, the present invention is not limited to this, and the light amount of the light source can be controlled by controlling the applied current. You may comprise so that it may adjust.

108 Operation Panel 109 Display Unit 101A CPU
106 Document Detection Unit 141A First Light Source 141B Second Light Source 130 Document Placement Table P Document T Reception Screen 144 CCD
145, 146 LED

Claims (6)

In an image reading apparatus comprising means for irradiating a document placed on a document table with light from a moving light source and scanning the document to read an image,
Two light sources arranged opposite to each other in the moving direction;
A detector for detecting the amount of light from each light source;
An image reading apparatus comprising: adjusting means for adjusting a voltage or a current applied to the two light sources based on a detection result of the detection unit. The document table is rectangular, and the scanning is performed from one end side of the document table to the other end side facing the one end side,
A reception means for receiving a predetermined instruction from the outside,
When the accepting means accepts the instruction,
The adjusting means is configured to adjust a voltage or a current applied to a light source on the other end side of the document table among the two light sources to be higher than a light source on one end side. The image reading apparatus according to 1. A position detecting means for detecting positions of the two light sources with respect to the document;
The image reading apparatus according to claim 1, wherein the adjustment unit is configured to adjust a voltage or a current applied to the two light sources based on a detection result of the position detection unit. A reception means for receiving a predetermined instruction from the outside,
When the receiving means receives the instruction,
The image reading apparatus according to claim 3, wherein the adjustment unit is configured to change a voltage or a current applied to the two light sources based on a detection result of the position detection unit.   The image reading apparatus according to claim 1, wherein the light source includes an LED, a halogen lamp, and / or a xenon lamp. An image reading device according to any one of claims 1 to 5, comprising:
An image forming apparatus configured to form an image on a sheet based on image data of an image read by the image reading apparatus.

Images