JP2011035782A - Image reading apparatus provided with ion generator, and image data output processing apparatus - Google Patents

Abstract

In an image reading apparatus for irradiating a document placed or transported on a document table with light emitted from a light source and generating image data of the document based on reflected light from the document, charging of the document table Therefore, it is possible to easily and appropriately prevent latch-up from occurring in an IC (semiconductor integrated circuit) provided in the image reading apparatus.
A light source control unit having an IC for controlling a lighting state of a light source provided in a light source unit, and ions are generated, and the generated ions are ejected onto the document table to thereby change the document table. An ion generator 171 for removing static electricity is provided.
[Selection] Figure 1

Description

  The present invention relates to an image reading apparatus that reads an original and generates image data of the original, and an image data output apparatus such as an image forming apparatus, an image transmission apparatus, and an image storage apparatus provided with the image reading apparatus.

  2. Description of the Related Art Conventionally, an image reading apparatus that optically reads a document placed or conveyed on a document table, and an image output apparatus such as a copying machine, a facsimile machine, and a multifunction machine equipped with such an image reading apparatus have been used. Yes.

  However, this type of apparatus has a problem that, when a charged document is placed or transported on the document table, the document table is charged, which causes various problems. When the platen is made of glass, the glass is more charged than the paper (the one that tends to be charged positively when the two types of materials are rubbed together is higher, and the one that tends to be charged negatively is lower. In general, the document table is positively charged and the original is negatively charged.

  For example, Patent Document 1 includes an automatic document feeder that automatically conveys a document to an image reading position on a document plate made of a glass plate by a conveyance belt or the like, and automatically retrieves the document from the document plate after the image reading is completed. In the above configuration, it is described that when the document table is charged, the document is attracted to the document table to cause a conveyance failure. In Patent Document 1, a warning is given according to the detection result of the charged amount of the document table, and when the warning is issued, a service person or an operator applies a neutralizing agent to the document table to prevent a conveyance failure. ing.

  Further, Patent Document 2 describes that in an electrostatic adsorption device that electrostatically adsorbs paper, when papers before electrostatic attraction are charged, the papers are brought into close contact with each other to cause double feeding. In Patent Document 2, double feeding is prevented by applying positive and negative ions to a sheet before electrostatic attraction.

  In addition to the problems related to the conveyance of paper as described in Patent Documents 1 and 2 above, abnormal operation of various electronic components provided in the apparatus may occur due to charging of the document table.

  For example, Patent Document 3 describes that static electricity is generated by a charge charged on a document between the time the document is fed and the paper is discharged, and abnormalities occur in electrical components and the like due to the generated static electricity. Yes. In Patent Document 3, an abutting plate that restricts movement of the original bundle placed on the original table from the original table is provided, and a neutralizing brush that removes electric charges charged on the original is provided on the abutting plate, By neutralizing the document before being fed, static electricity generated between the time when the document is fed and the time when the document is ejected is reduced to prevent the above abnormality.

  Patent Document 4 describes that latch-up of a semiconductor device occurs when a voltage equal to or higher than a predetermined value is applied to an input / output pin of the semiconductor device. In Patent Document 4, in order to prevent latch-up of a semiconductor device, latch-up is performed by connecting the input / output pin to a low potential source when a voltage higher than a predetermined value is applied to the input / output pin of the semiconductor device. Is preventing.

  Latch-up is a phenomenon in which ICs do not operate normally due to the operation of parasitic elements inside the IC when excessive noise or surge exceeding the power supply voltage is applied to the input / output terminal or power supply terminal of the IC. It is known that when latch-up occurs, a large current continues to flow between the power supply and GND without returning to the original state unless the power supply is turned off or the power supply voltage is lowered.

JP-A-8-81077 (published March 26, 1996) JP-A-10-109775 (April 28, 1998) JP 2007-168947 A (July 5, 2007) JP-A-6-21324 (January 28, 1994)

  When the document table is charged in the image reading apparatus configured to irradiate the document on the document table with light from the light source and generate image data of the document based on the reflected light from the document, the image forming apparatus is caused by the charging. There is a problem that latch-up occurs in the IC provided in the IC. For example, when a light source lighting control IC is latched up, a light source lighting failure may occur.

  When the latch-up due to the charging of the document table occurs, in order to eliminate the latch-up, (i) a process of eliminating the charge of the document table to eliminate the charging of the document table, and (ii) an image It is necessary to perform processing to eliminate latch-up by turning the power of the reading device off and then on again, which is very time-consuming and takes time to restart the image reading processing. End up.

  In the technique of Patent Document 1, when charging of the document table is detected, it is necessary for a service person or an operator to apply a neutralizing agent to the document table. It takes a lot of work and time before the reading process can be performed.

  Further, in the techniques of Patent Documents 2 and 3, although charging can be suppressed to some extent by applying ions to the sheet before electrostatic adsorption and starting conveyance after discharging the sheet, for example, Since the sheet may be charged due to friction generated between the sheet and the sheet conveying means during sheet conveyance, charging of the document table cannot be completely suppressed.

  In the technique of Patent Document 4, latch-up can be prevented by connecting the input / output pin to a low potential source when a voltage higher than a predetermined value is applied to the input / output pin of the semiconductor device. While the output pin is connected to the low potential source, the semiconductor device cannot perform its original function, so that the image reading process cannot be performed. In other words, the cause of the latch-up is not eliminated unless the platen is neutralized, so that the input / output pins remain connected to the low potential source, and eventually the image reading process can be performed until the neutralization of the platen is performed. Can not.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to irradiate light emitted from a light source onto a document placed or transported on a document table, and based on reflected light from the document. An object of the image reading apparatus for generating image data of an original is to easily and appropriately prevent latch-up from occurring in an IC provided in the image reading apparatus due to charging of an original table.

  In order to solve the above problems, an image reading apparatus according to the present invention includes a document table, a light source that irradiates light on a document placed or conveyed on the document table, a light source emitted from the light source, and An image reading apparatus including an imaging unit that receives reflected reflected light and converts it into an electrical signal to generate image data of the original, and controls operations of electrical components included in the image reading apparatus And a circuit board having a semiconductor integrated circuit, and an ion generator for generating ions and discharging the generated ions onto the document table to neutralize the document table.

  According to said structure, an ion generator produces | generates ion and discharges the said original stand by ejecting the produced | generated ion to the said original stand. Thereby, it is possible to easily and appropriately prevent the semiconductor integrated circuit from being latched up due to charging of the document table.

  Further, a switching element for switching the light source between a lighting state and a light-off state may be provided, and the semiconductor integrated circuit may be configured to control the operation of the switching element.

  According to the above configuration, since the latch-up of the semiconductor integrated circuit can be prevented, it is possible to prevent the malfunction of the switching element due to the latch-up of the semiconductor integrated circuit and the lighting failure of the light source.

  And a step-up transformer that boosts a voltage applied to the primary coil and supplies the voltage from the secondary coil to the light source. The switching element includes a gate electrode connected to the semiconductor integrated circuit and a drain electrode connected to the semiconductor integrated circuit. A field effect transistor connected to a power supply voltage source via a primary coil of a step-up transformer and having a source electrode grounded via an electric resistor, and the semiconductor integrated circuit controls a voltage applied to the gate electrode; The light source is switched between a light-on state and a light-off state by switching the field effect transistor between a conductive state and a cut-off state, and a detection signal corresponding to the potential of the source electrode is output to the semiconductor integrated circuit. An overcurrent detection unit, and the field effect transistor provided in the semiconductor integrated circuit, when the potential of the detection signal is a potential indicating an overcurrent. An emergency cut-off circuit that switches the circuit to a cut-off state, a potential difference detection unit that detects a potential difference between the potential of the detection signal and the ground potential, and a potential difference detected by the potential difference detection unit with respect to a potential at which latch-up occurs in the semiconductor integrated circuit And a control unit that controls the ion generating device to inject ions onto the document table when the value exceeds a predetermined value set to a value that takes into account a predetermined safety factor.

  According to the above configuration, the input potential to the semiconductor integrated circuit is out of the predetermined range due to the charging of the document table based on the potential difference between the potential of the input signal from the overcurrent detection unit to the emergency cut-off circuit and the ground potential. When it is detected that the document is out of the predetermined range, it is possible to automatically perform the neutralization process on the document table. As a result, the latch-up of the semiconductor integrated circuit can be easily and appropriately prevented without increasing the user's effort.

  A detector that detects the amount of charge on the document table; and a control unit that controls the ion generator to inject ions onto the document table when the amount of charge detected by the detector is equal to or greater than a predetermined value. It is good also as a structure provided with.

  According to the above configuration, since the neutralization process of the document table is automatically performed when the charging amount of the document table exceeds a predetermined value, the semiconductor integrated circuit can be latched up without increasing the user's effort. It can be prevented easily and appropriately.

  The controller may be configured to stop the operation of the ion generator during a period when the document table is not neutralized.

  According to said structure, power consumption can be reduced by stopping operation | movement of an ion generator during the period which does not neutralize a platen.

  The document table may be made of glass, and the ion generator may generate at least negative ions and eject the negative ions onto the document table.

  When the document table is made of glass as in the above configuration, the document table is positively charged and the document is negatively charged. Therefore, by generating negative ions by the ion generator and ejecting the negative ions onto the document table, the document table can be appropriately neutralized.

  Further, the ion generator may be configured to generate positive ions and negative ions and inject them onto the document table.

  According to the configuration described above, ions having the same polarity as the charged polarity of the document table are repelled by the document table, and ions of the opposite polarity are attracted to the document table, so that the document table can be appropriately neutralized.

  The ion generator includes an ion generation unit that generates positive ions and negative ions, a first duct that injects positive ions and negative ions generated by the ion generation unit onto the document table, and the ion generation unit. A second duct for discharging the positive ions and negative ions generated by the unit to the outside of the image reading device, and the transport destination of the positive ions and negative ions generated by the ion generating unit as the first duct or the second duct. A switching unit for switching to any one of the above, and when neutralizing the document table, ions generated by the ion generation unit are jetted onto the document table via the first duct, and the document table During the period during which no static elimination is performed, the operation of the switching unit is controlled so that ions generated by the ion generation unit are released to the outside of the image reading apparatus via the second duct. Switching control unit which may Configurations which comprises a.

  According to the above-described configuration, when performing neutralization of the document table, it is possible to appropriately neutralize the document table by ejecting positive ions and negative ions generated by the ion generation unit from the first duct to the document table. Further, during the period when the platen is not neutralized, positive ions and negative ions generated by the ion generator are discharged from the second duct to the outside of the image reading device, thereby cleaning the air around the image reading device. Can be sterilized.

  The semiconductor integrated circuit may be disposed below the document table, and the ion generator may be configured to eject ions onto the upper surface of the document table.

  According to the above configuration, by performing the charge removal process on the document table, it is possible to more effectively prevent the latch-up of the semiconductor integrated circuit due to the charging of the document table.

  An image data output processing device according to the present invention includes any one of the above-described image reading devices, an image forming process for forming an image on a recording material according to image data of a document generated by the image reading device, and the image data And an output processing unit for performing at least one of image transmission processing for transmitting the image data to another device and image storage processing for storing the image data in a storage medium.

  According to the above configuration, it is possible to appropriately generate the image data of the document and to output the generated image data by preventing the operation failure caused by the charging of the document table in the image reading apparatus.

  As described above, the image reading apparatus of the present invention generates a circuit board having a semiconductor integrated circuit for controlling the operation of an electrical component provided in the image reading apparatus, and generates the ions, and ejects the generated ions onto a document table. By so doing, an ion generator is provided that neutralizes the document table.

  Therefore, latch-up of the semiconductor integrated circuit due to charging of the document table can be easily and appropriately prevented.

1 is a cross-sectional view showing an embodiment of an image forming apparatus according to an embodiment of the present invention. (A) is a side view of a light source control unit provided in the image forming apparatus of FIG. 1, and (b) is a top view thereof. FIG. 2 is a circuit diagram of a light source control unit provided in the image forming apparatus of FIG. 1. (A) is a front view of the image forming apparatus of FIG. 1, and (b) is a side view thereof. FIG. 2 is an explanatory diagram illustrating an outline of a charge removal process in the image forming apparatus of FIG. 1. (A) is sectional drawing of the ion generator with which the image forming apparatus of FIG. 1 is equipped, (b) is a top view of the ion generating element with which the said ion generator is equipped. (A) is sectional drawing of the periphery of the light source unit with which the image forming apparatus of FIG. 1 is equipped, (b) is sectional drawing of the said light source unit.

  An embodiment of the present invention will be described.

  FIG. 1 is a cross-sectional view of an image forming apparatus (image data output processing apparatus) 100 according to the present embodiment. As shown in this figure, the image forming apparatus 100 includes a document reading device (image reading device) 101, an image forming unit 110, and a communication device (not shown).

(1-1. Configuration of Document Reading Device 101)
The document reading apparatus 101 includes a document transport unit 120, a scanner unit 90, a light source control unit 130, and an ion generator 171.

  The document transport unit 120 picks up the documents placed on the document set tray 41 one by one and transports them to the document reading position of the scanner unit 90 set on the document table 92, and the document reading process by the scanner unit 90 is performed. The original after being performed is discharged to the paper discharge tray 59.

  Specifically, when a document is set on the document set tray 41, the document transport unit 120 rotates the document pickup roller 44 while pressing it against the document surface, and pulls out the document set on the document set tray 41. Then, the drawn document is supplied between the suction roller 45 and the separation pad 46, so that only one document is separated from the other documents and is transported to the conveyance path 47.

  In the conveyance path 47, the leading edge of the document is brought into contact with the document registration roller 49 to align the leading edge of the document in parallel with the extending direction of the document registration roller 49, and then the document registration roller 49 is rotated to convey the document. Then, it passes between the reading guide 51 and the first reading position 52 on the document table 92. Further, the document that has passed through the first reading position 52 is transported by the transport roller 60 and finally discharged onto the paper discharge tray 59 via the paper discharge roller 58.

  The scanner unit 90 optically reads a document and converts it into image data, and includes a document table 92, a light source unit 54, a mirror unit 53, and a CCD (Charge Coupled Device) unit 56.

  The document table 92 is a transparent member provided so that the document conveyed by the document conveying unit 120 can be read by the CCD unit 56 or the like, and is made of, for example, glass.

  FIG. 7A is a sectional view around the light source unit 54, and FIG. 7B is a sectional view of the light source unit 54. As shown in these drawings, the light source unit 54 includes a base 112, a light source 111, a first mirror (reflector) 113, a slit 114, and a second mirror 115. The light source unit 54 is provided with a lighting circuit 135 that is a main part of a light source control unit 130 described later. The first mirror 113 collects the irradiation light from the light source 111 at a predetermined position on the document table 92. The slit 114 allows only the reflected light reflected by the original to pass by irradiating the original with the irradiation light. The second mirror 115 changes the optical path of the reflected light that has passed through the slit 114 by about 90 degrees and emits it toward the mirror unit 53. In the present embodiment, a cold cathode ray tube lamp (xenon lamp) is used as the light source 111. The lighting state of the light source 111 is controlled by a light source control unit 130 described later.

  The mirror unit 53 includes a pair of mirrors, and the pair of mirrors changes the optical path of the reflected light from the document emitted from the light source unit 54 by 180 degrees and emits the light toward the CCD unit 56.

  The CCD unit 56 includes an imaging lens 55 and a CCD (imaging unit) 57. Then, the reflected light from the document emitted from the mirror unit 53 is imaged on the detection surface of the CCD 57 by the imaging lens 55, whereby the reflected light from the document is converted into an electric signal by the CCD 57, and the image data of the document is converted. Generate.

  When reading a document conveyed by the document conveying unit 120, the light source unit 54 and the mirror unit 53 are arranged at predetermined positions corresponding to the first reading position 52, and the first on the reading guide 51 and the document table 92. When passing between the reading position 52 and the light, the light from the light source 111 of the light source unit 54 is applied to the original through the original table 92, and the reflected light enters the light source unit 54 through the original table 92. The reflected light is guided to the imaging lens 55 of the CCD unit 56 through the light source unit 54 and the mirror unit 53, and is imaged on the CCD 57 by the imaging lens 55.

  Further, the document reading apparatus 101 can read not only the document conveyed by the document conveying unit 120 but also the document placed on the document table 92.

  Specifically, the document conveying unit 120 is supported so as to be openable and closable around an end on the back side of the document reading apparatus 101. When the document conveying unit 120 is opened, the document table 92 is exposed, and the user places the document table The document can be manually placed on the 92. When a document is placed on the document table 92 and the document conveyance unit 120 is closed, the light source unit 54 and the mirror unit 53 move in the sub-scanning direction, and the surface of the document on the document table 92 is exposed by the light source unit 54. The reflected light from the document is imaged on the CCD 57 via the document table 92, the light source unit 54, the mirror unit 53, and the imaging lens 55. At this time, the moving speed (positional relationship) of the light source unit 54 and the mirror unit 53 is controlled so that the optical path length of the reflected light from the document surface to the CCD 57 is kept constant. Thereby, the focus of the original image on the CCD 57 is always accurately maintained.

  The document image data acquired as described above is sent to a control unit (not shown) of the image forming apparatus 100, and the control unit controls the operation of each unit of the image forming unit 110 according to the image data. Thus, an image corresponding to the image data of the original is formed on the recording material. Note that the image data of the document acquired by the document reading apparatus 101 may be transmitted to another apparatus via a communication unit (not shown), and is attached to or detached from the storage unit provided in the image forming apparatus 100 or the image forming apparatus 100. You may make it memorize | store in the memory | storage part mounted | worn freely.

  The light source control unit 130 controls the lighting state (ON / OFF) of the light source 111 provided in the light source unit 54. The light source control unit 130 is provided near the bottom surface of the document reading apparatus 101 and is connected to the light source 111 by a cable (not shown). Yes. The light source control unit 130 turns on the light source 111 when performing a document reading process, and turns off the light source 111 during a period when the reading process is not performed. Details of the light source control unit 130 will be described later.

  The ion generator 171 generates positive ions and negative ions, and discharges the generated ions toward the document table 92. Details of the ion generator 171 will be described later.

(1-2. Configuration of Image Forming Unit 110)
The image forming unit 110 forms a color or monochrome image on a recording material according to image data obtained by reading a document or image data received from the outside via a communication device (not shown). .

  As shown in FIG. 1, the image forming unit 110 includes a laser exposure device 1, image forming units pa to pd, an intermediate transfer unit 6, a secondary transfer device 10 a, a fixing device 7, a paper transport path S, and a paper feed tray 81. , And a paper discharge tray 91.

  The image data handled in the image forming apparatus 100 corresponds to a color image using each color of black (K), cyan (C), magenta (M), yellow (Y), or a single color (for example, black). This corresponds to a monochrome image using. For this reason, the image forming apparatus 100 includes four sets of image forming units pa to pd corresponding to the respective colors. The toner images of the respective colors formed by these four sets of image units are superimposed on the intermediate transfer belt 61. It is designed to transfer together. That is, the image forming units pa to pd form toner images of black (K), cyan (C), magenta (M), and yellow (Y), respectively, and the intermediate transfer belt so that these toner images overlap each other. Transfer to 61.

  In the image forming unit pa, a charger 5, a developing device 2, and a cleaner device 4 are disposed around a photosensitive drum 3 (image carrier) 3 that is rotatably provided along the rotation direction of the photosensitive drum 3. The configuration is arranged in the order of levers.

  The charger 5 is for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. In the present embodiment, a charging roller type (contact charging type) is used as the charger 5. However, the configuration of the charger 5 is not limited to this. For example, a non-contact charger such as a corona discharge method may be used, or a contact charger such as a brush charger may be used.

  The laser exposure apparatus 1 exposes the surface of the photosensitive drum 3 charged by the charger 5 according to image data, thereby forming an electrostatic latent image according to the image data on the surface of the photosensitive drum 3. belongs to. For the laser exposure apparatus 1, for example, a laser scanning unit (LSU) including a light source and a reflection mirror is used.

  The developing device 2 develops the electrostatic latent image formed on the photosensitive drum 3 with toner. As the toner, for example, a non-magnetic one-component developer (non-magnetic toner), a non-magnetic two-component developer (non-magnetic toner and carrier), a magnetic developer (magnetic toner) and the like can be used.

  The toner image visualized by the developing device 2 is transferred onto the intermediate transfer belt 61 by an intermediate transfer roller 64 provided in the intermediate transfer unit 6. The intermediate transfer roller 64 is disposed at a position facing the photosensitive drum 3 via the intermediate transfer belt 61.

  The cleaner device 4 is for removing and collecting the toner remaining on the surface of the photosensitive drum 3 after the toner image is transferred to the intermediate transfer belt 61.

  The image forming units pb to pd have substantially the same configuration as the image forming unit pa except that the color of the toner used for the development processing is different. That is, black (B), yellow (Y), magenta (M), and cyan (C) toners are stored in the developing units of the image forming units pa to pd, respectively.

  The intermediate transfer unit 6 includes an intermediate transfer belt 61, an intermediate transfer belt driving roller (tension roller) 62, an intermediate transfer belt driven roller (tension roller) 63, an intermediate transfer belt cleaning unit 65, and four intermediate transfer rollers 64. And.

  The intermediate transfer belt 61 is an endless belt made of a film having a thickness of about 100 μm to 150 μm, and is suspended from each intermediate transfer roller 64, the intermediate transfer belt drive roller 62, and the intermediate transfer belt driven roller 63. It is provided in contact with the photosensitive drum 3 and is driven to rotate. The toner images of the respective colors formed on the photosensitive drum 3 are transferred so as to sequentially overlap the intermediate transfer belt 61, and a color toner image (multicolor toner image) is formed on the intermediate transfer belt 61. It has become.

  Each intermediate transfer roller 64 is disposed so as to face the photosensitive drum 3 through the intermediate transfer belt 61 at a position between the facing portion of the photosensitive drum 3 facing the developing device 2 and the facing portion of the cleaner device 4. Has been. By applying a high voltage (+) opposite to the toner charging polarity (−) to the intermediate transfer roller 64, the toner image on the photosensitive drum 3 is superimposed and transferred onto the intermediate transfer belt 61. It is like that. Each 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). By this conductive elastic material, a high voltage can be uniformly applied to the recording paper.

  The toner image formed on the intermediate transfer belt 61 is conveyed to a facing portion between the intermediate transfer belt driving roller 62 and the secondary transfer device 10a, and transferred onto a recording material such as a recording sheet conveyed to the facing portion. It has become so.

  The intermediate transfer belt 61 and the transfer roller 10 of the secondary transfer device 10a are pressed against each other to form a nip region. In addition, the transfer roller 10 of the secondary transfer device 10a has a voltage (high polarity (+) opposite to the toner charge polarity (-)) for transferring the toner image of each color on the intermediate transfer belt 61 onto the recording paper. Voltage) is applied. In order to obtain the nip area constantly, either the transfer roller 10 or the intermediate transfer belt drive roller 62 of the secondary transfer device 10a is made of a hard material (metal or the like), and the other is a soft material such as an elastic roller. (Such as an elastic rubber roller or a foaming resin roller).

  Further, the toner image on the intermediate transfer belt 61 may not be completely transferred onto the recording paper by the secondary transfer device 10a, and the toner may remain on the intermediate transfer belt 61. In this process, toner color mixture occurs. Therefore, the residual toner is removed and collected by the intermediate transfer belt cleaning unit 65. The intermediate transfer belt cleaning unit 65 is provided with, for example, a cleaning blade as a cleaning member that comes into contact with the intermediate transfer belt 61 to remove residual toner. The back side of the intermediate transfer belt 61 is supported.

  The paper feed tray 81 is a tray for storing recording paper (recording material), and is provided below the image forming unit 110.

  The image forming unit 110 is provided with a paper transport path S for sending the recording paper supplied from the paper feed tray 81 to the paper discharge tray 91 via the secondary transfer device 10 a and the fixing device 7. Along the paper conveyance path S, a paper pickup roller 11a, a paper conveyance roller 12a, a paper registration roller 13, a secondary transfer device 10a, a fixing device 7, a paper conveyance roller 12b, and the like are arranged.

  The paper pickup roller 11 a is a calling roller that is provided at the end of the paper feed tray 81 and supplies recording paper from the paper feed tray 81 to the paper transport path S one by one. The paper transport rollers 12 a and 12 b are small rollers for promoting and assisting the transport of the recording paper, and a plurality of paper transport rollers 12 a and 12 b are provided along the paper transport path S.

  The paper registration roller 13 temporarily stops the recording paper that has been conveyed, aligns the leading edge of the recording paper, and in the nip region between the intermediate transfer belt 61 and the transfer roller 10 of the secondary transfer device 10a, the intermediate transfer belt. The recording paper is conveyed in a timely manner in accordance with the rotation of the photosensitive drum 3 and the intermediate transfer belt 61 so that the toner image on 61 is transferred to a predetermined position on the recording paper.

  The fixing device 7 includes a fixing roller 71 and a pressure roller (pressure member) 72 that is pressed against the fixing roller 71 with a predetermined load, and the conveyance direction of the recording paper is greater than that of the secondary transfer device 10a. It is arranged downstream. The fixing roller 71 is temperature-controlled so as to reach a predetermined fixing temperature based on a detection output of a temperature detector (not shown). Then, the fixing device 7 feeds the recording paper onto which the toner image has been transferred by the secondary transfer device 10a to the pressure contact portion (fixing nip portion) between the fixing roller 71 and the pressure roller 72, and passes this pressure contact portion. Thus, the toner image is fixed on the recording material by heat and pressure. Note that the surface of the recording material on which the unfixed toner image is formed contacts the fixing roller 71, and the surface of the recording material opposite to the surface on which the unfixed toner image is formed contacts the pressure roller 72.

  The recording paper on which the toner image of each color is fixed by the fixing device 7 is discharged face down on the paper discharge tray 91 by the paper transport roller 12b.

(1-3. Configuration of Light Source Control Unit 130)
FIG. 3 is a circuit diagram of the light source control unit 130.

  As shown in FIG. 3, the light source control unit 130 includes a circuit board 131, a switching FET (field effect transistor) 153, a step-up transformer 160, and a control unit 170. The circuit board 131, the switching FET 153, and the step-up transformer 160 constitute a lighting circuit 135 that controls the lighting state of the light source 111. As shown in FIG. 1, the control unit 170 is attached to the lower surface of the metal casing (frame) 103 of the document reading apparatus 101, and the lighting circuit 135 is attached to the light source unit 54.

  2A is a side view of the lighting circuit 135, and FIG. 2B is a top view of the lighting circuit 135. As shown in these drawings, each member constituting the lighting circuit 135 is accommodated in a housing 134. Further, a heat radiating plate 132 made of a metal having high thermal conductivity such as aluminum is attached to the circuit board 131 and the switching FET 153. The circuit board 131, the switching FET 153, and the heat radiating plate 132 are provided with mounting holes. The circuit board 131 and the heat radiating plate 132, and the switching FET 153 and the heat radiating plate 132 are respectively shared by screws through the holes. By tightening, the circuit board 131 and the switching FET 153 are attached to the heat sink 132.

  The switching FET 153 is a light source lighting control circuit for controlling ON / OFF of the power supplied to the light source 111 provided in the light source unit 54, and the output terminal of the light source lighting control IC 161 provided in the circuit board 131 and the step-up transformer 160. It is electrically connected to the primary coil. The step-up transformer 160 boosts the power supply voltage output from the switching FET 153 and supplies it to the light source 111.

  Specifically, the gate electrode of the switching FET 153 is connected to the light source lighting control IC 161 of the circuit board 131, and the drain electrode is connected to the supply source of the power supply voltage VCC having a predetermined frequency via the primary side coil of the step-up transformer 160. The source electrode is connected to the module B167 of the circuit board 131 and grounded via the resistor R1. The resistor R1 and the module B167 are for detecting an overcurrent of the switching FET 153.

  When the light source 111 is turned on, the switching FET 153 operates to energize the power supply voltage VCC to the primary coil of the step-up transformer 160 in accordance with a control signal from the light source lighting control IC 161 of the circuit board 131, thereby boosting the voltage. A high voltage is generated in the secondary coil of the transformer 160, and this high voltage is supplied to the light source 111. Note that one end of the secondary side coil of the step-up transformer 160 is connected to the light source lighting control IC 161 of the circuit board 131 via the resistor R2, so that the light source lighting control IC 161 generates the voltage of the secondary side coil of the step-up transformer 160. The voltage is detected and feedback controlled.

  The heat radiating plate 132 is for radiating the heat generated in the switching FET 153 to the outside, and the switching FET 153 is attached to the heat radiating plate 132. Since the heat sink 132 occupies a large area in the lighting circuit 135, the heat sink 132 is easily affected by the charging potential of the document table 92. When the document plate 92 is charged, the heat sink 132 is placed on the document table 92. Is charged to a potential of the opposite polarity.

  Specifically, as shown in FIG. 7A, due to the friction between the document table 92 and the document, the upper surface of the document table 92 made of glass (contact surface with the document) is positively charged and is made of paper. The document is negatively charged. Accordingly, the lower surface of the document table 92 is negatively charged due to dielectric polarization, a negative electric field is generated in the space between the lower surface of the document table 92 and the housing 103, and the heat radiating plate 132 disposed in this space is Charge. Further, the charging potential of the heat sink 132 is input to the terminal of the circuit board 131 connected to the heat sink 132.

  As shown in FIG. 3, the circuit board 131 includes a light source lighting control IC 161, a module B167, and a module D168. The light source lighting control IC 161 includes an oscillator (OSC) 162, a module A163, a module C164, a driver 165, and a module E166.

  The light source lighting control IC 161 is a switching power supply control IC that controls driving of the switching FET 153.

  The oscillator 162 is an oscillator for driving the switching FET 153 to be turned on / off at a predetermined frequency.

  The module A163 drives the module E166 by controlling the output voltage to the module E166 based on the voltage of the oscillation output from the oscillator 162 and the drive voltage of the light source 111 fed back from one end of the resistor R2.

  The module E (emergency cut-off circuit) 166 is driven by the output of the module A 163 and the output of the module C 164 described later, and drives the switching FET 153 via the driver 165.

  The driver (emergency cut-off circuit) 165 includes two transistors 165a and 165b connected in series, and the potential of the control signal to the gate electrode of the switching FET 153 is set to the Vcc potential (power supply) according to the polarity of the output from the module E166. Potential) or ground potential. As a result, the switching FET 153 is turned ON / OFF at a predetermined frequency.

  The module B (overcurrent detection unit) 167 is for detecting the overcurrent of the switching FET 153 based on the feedback voltage from the source electrode of the switching FET 153 as described above. Specifically, the module B167 outputs a signal having a potential corresponding to the voltage value of the feedback voltage to the module C164. In the present embodiment, when the feedback voltage exceeds a preset threshold value (voltage value indicating an overcurrent), the potential of the output signal to the module C164 becomes a predetermined output potential (+5 V). It is set as follows.

  The module C 164 controls the output to the module E 166 when the output potential from the module B 167 input via the input terminal to the light source lighting control IC 161 is a value indicating that an overcurrent flows through the switching FET 153. Then, the module E166 is operated so as to turn off the switching FET 153. Thereby, the overcurrent state of the switching FET 153 is eliminated.

  Module D (potential difference detection unit) 168 detects the potential difference between the input potential from module B 167 to module C 164 and the ground potential, and transmits a signal indicating whether or not this potential difference has become a predetermined value or more to control unit 170.

  When the potential difference becomes equal to or greater than a predetermined value, the control unit 170 determines that the document table 92 is charged beyond an allowable range, and discharges ions generated by the ion generator 171 toward the document table 92. Thus, the document table 92 is neutralized.

  The predetermined value is set to a value in consideration of a predetermined safety factor with respect to a potential difference that actually causes latch-up so that latch-up can be reliably prevented. That is, the predetermined value is set to a value at which latch-up is expected to occur in the near future when the document reading process is continued without discharging the document table 92. For example, when the latch-up of the light source lighting control IC 161 occurs when the input potential of the module C164 falls below the ground potential by 10V, the predetermined value is set to a potential 5V lower than the ground potential, and the module C164 What is necessary is just to comprise so that charging may be alert | reported when an input electric potential is 5V below a grounding electric potential.

  When the document table 92 is charged, the heat radiating plate 132 is charged due to the influence. When the heat radiating plate 132 is charged, due to the influence, the potential of the feedback voltage from the source electrode of the switching FET 153 input to the module B167 is lowered, and the input potential of the module C164 is lowered. When the input potential of the module C164 drops below a certain value, latch-up occurs in the parasitic transistor provided in the module E166. Since the module E166 is an output stage of the control signal to the switching FET 153, the occurrence of latch-up in the module E166 is directly connected to the control abnormality (lighting failure) of the switching FET 153. Therefore, in this embodiment, the input potential of the module C164 is monitored by the module D168, and when the input potential drops below a predetermined value, the control unit 170 charges the document table 92 beyond the allowable range. Judge. Thus, by monitoring the input potential of the module C164, the influence of charging of the document table 92 can be detected most sensitively.

(1-4. Ion generator 171)
4A is a front view of the image forming apparatus 100, and FIG. 4B is a side view of the image forming apparatus 100 viewed from the direction of arrow A shown in FIG. 4A. As shown in this figure, the ion generator 171 is disposed on one side of the document reader 101 above the document table 92.

  5A is a cross-sectional view of the ion generator 171, and FIG. 5B is a side view of the ion generating element 185 provided in FIG. 5A viewed from the direction of arrow A shown in FIG. FIG.

  As shown in FIG. 5A, the ion generator 171 includes a housing 181, a fan unit 182 disposed in the lower portion of the housing 181, and a plurality of suction holes 181 a formed in the lower side wall of the housing 181. A suction duct 183 disposed between the suction hole 181a and the suction port 182a of the fan unit 182; A duct 184 and a plurality of ion generating elements 185 arranged around a fan 182c provided in the fan unit 182 are provided.

  The ion generator 171 has a shape extending in the depth direction of the image forming apparatus 100 as shown in FIG. 4B, and includes a housing 181, each suction hole 181a, a suction duct 183, and a fan unit. 182, the blowout duct 184, and the blowout port 181b are also shaped to extend in the depth direction of the image forming apparatus 100. Further, as shown in FIG. 5B, a plurality of ion generating elements 185 are arranged side by side in the depth direction of the image forming apparatus 100.

  In addition, a blowout port 181b formed in the upper part of the housing 181 generates a first duct 186a for discharging ions generated by the ion generator 171 toward the upper surface of the document table 92, and is generated by the ion generator 171. A second duct 186b is connected to discharge the generated ions to the outside of the image forming apparatus 100 (original reading apparatus 101).

  In addition, a switching plate 186 is provided at a connection portion between the air outlet 181b and the first duct 186a and the second duct 186b. The switching plate 186 is rotatably supported by a shaft member having one end connected to a driving means (not shown) including a motor, a gear, and the like, and the control unit 170 controls the operation of the driving means. Thus, the shaft member rotates about the shaft member (fulcrum), and either the first duct 186a or the second duct 186b is closed. As a result, ions generated by the ion generator 171 are discharged to either the first duct 186a or the second duct 186b. Note that the controller 170 discharges ions generated by the ion generator 171 toward the document table 92 via the first duct 186a when discharging the document table 92, and in other cases, the ion generator. The operation of the switching plate 186 is controlled so that the ions generated in 171 are released to the outside of the image forming apparatus 100 through the second duct 186b.

  When the fan 182c of the fan unit 182 is rotationally driven by a driving means such as a motor (not shown), as indicated by an arrow G in FIG. 5A, the suction hole 181a and the suction port 182a are connected through the suction duct 183a. Air is sucked into the fan unit 182, and the sucked air passes through the vicinity of each ion generating element 185 and passes through the outlet 182 b and the outlet duct 184 together with positive ions and negative ions generated by the ion generating element 185. It discharges | emits from the blower outlet 181b to the 1st duct 186a or the 2nd duct 186b. The operation of the driving means of the fan 182c is controlled by the control unit 170.

  In the present embodiment, a plasma cluster ion (registered trademark) generation element (PCI) is used as each ion generation element 185, and two ion generation elements 185 are provided as shown in FIG. 100 are arranged side by side in the depth direction.

Each ion generating element 185 includes a plurality of sets of first electrode 185a and second electrode 185b arranged so as to face each other through an insulator (not shown) such as glass, and the first electrode 185a and the second electrode 185a. By applying an AC voltage between the electrode 185b, positive ions and negative ions are generated simultaneously. Specifically, H ⁺ ions are mainly generated from water molecules in the air, and O ₂ ⁻ ions are generated from oxygen molecules. In addition, water molecules are attached in the form of clusters around these H ⁺ ions and O ₂ ⁻ ions to generate cluster ions.

  For each of these electrodes, for example, a conductive oxidation resistant material such as stainless steel is used. Such an ion generating element 185 is disclosed in detail in, for example, Japanese Patent Application Laid-Open No. 2002-58731 (Reference 1) filed earlier by the applicant of the present invention.

  As described above, when the image forming apparatus 100 (original reading apparatus 101) according to the present embodiment detects that the original table 92 is charged to a predetermined value or more, the positive ions generated by the ion generator 171 and By discharging negative ions toward the document table 92, the document table 92 is neutralized.

  Accordingly, the document table 92 is neutralized, the light source control unit 130 is prevented from being latched up due to the charging of the document table 92, and the problem that the light source 111 is turned off during document reading can be prevented.

  FIG. 6 is an explanatory diagram for explaining a mechanism by which the document table 92 is neutralized by discharging positive ions and negative ions toward the document table 92.

  As described above, since the charged column is higher in the glass than in the paper, the document table 92 is positively charged. Therefore, positive ions released from the ion generator 171 onto the document table 92 repel the surface of the document table 92, and negative ions are attracted. As a result, the charge on the platen 92 is neutralized and the charge is eliminated.

  In the present embodiment, when the neutralization process of the document table 92 is not performed, ions generated by the ion generator 171 are released to the outside of the image forming apparatus 100 (document reading apparatus 101).

  Thereby, positive ions and negative ions are diffused around the image forming apparatus 100, and airborne bacteria and the like in the air are removed by these positive ions and negative ions to purify the air around the image forming apparatus 100. it can.

  Note that in an electrophotographic image forming apparatus, harmful exhaust gas mainly composed of longifolene or the like estimated to be generated from recording paper may be generated. In contrast, the positive ions and negative ions generated by the ion generator 171 as described above are released to the periphery of the image forming apparatus 100 to remove harmful components contained in the exhaust gas and to form the image forming apparatus. It is possible to prevent a person around 100 from feeling uncomfortable.

  By the way, in this embodiment, the present invention includes an original reading device (image reading device) 101 and an image forming unit 110 that forms an image on a recording material according to image data read from the original by the original reading device 101. The case of applying to the provided image forming apparatus (image data output processing apparatus) 100 has been described, but the application target of the present invention is not limited to this. For example, the present invention is applied to an image transmission device (image data output processing device) including a document reading device 101 and a communication device that transmits image data read by the document reading device 101 to another device that is communicably connected. Also good. Alternatively, the present invention may be applied to an image storage device (image data output processing device) including a document reading device 101 and a storage processing unit that stores image data read by the document reading device 101 in a predetermined storage medium. Examples of the storage medium include magnetic tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks / hard disks, and optical disks such as CD-ROM / MO / MD / DVD / CD-R. A disk system, a card system such as an IC card (including a memory card) / optical card, or a semiconductor memory system such as a mask ROM / EPROM / EEPROM / flash ROM can be used.

  Further, the configuration of the ion generating element provided in the ion generating apparatus 171 is not limited to the above-described configuration, and various conventionally known configurations can be used.

  In this embodiment, an ion generator that generates both positive ions and negative ions is used. However, the present invention is not limited to this, and only ions having a polarity opposite to the charged polarity of the surface on which the ions are ejected on the document table are used. A generating ion generator may be used. That is, when ions are ejected onto the upper surface of the document table 92, an ion generator that generates only negative ions may be used. In this case, the generated negative ions may be released to the outside of the image forming apparatus 100 when the document table 92 is not neutralized. Alternatively, the switching plate 186 and the second duct 186b may be omitted, and the discharge destination of the negative ions generated by the ion generator may be the original table 92 only.

  In this embodiment, positive ions and negative ions are released to the outside of the document reading apparatus 101 during a period when the document table 92 is not neutralized. However, the present invention is not limited to this, and the document table 92 is not neutralized. You may make it stop operation | movement of an ion generator during a period.

  In the present embodiment, ions generated by the ion generator 171 are emitted toward the upper surface of the document table 92, that is, the surface on which the document is placed and the surface on which the light source control unit 130 is disposed. ing. As a result, the document table 92 is neutralized, and adverse effects on the light source control unit 130 due to charging of the document table 92 can be prevented. The positive ions and negative ions generated by the ion generator 171 may be emitted toward the lower surface of the document table 92, or may be emitted toward both the upper surface and the lower surface of the document table 92. Also good. Further, only positive ions may be emitted toward the lower surface of the document table 92, negative ions may be emitted to the upper surface of the document table 92, and positive ions may be emitted to the lower surface of the document table 92. In any case, the document table 92 is neutralized, and the adverse effect on the light source control unit 130 due to the charging of the document table 92 can be prevented.

  Further, in the present embodiment, when the input potential to the module C provided in the light source lighting control IC 161 of the light source control unit 130 is compared with the ground potential, the input potential of the module C 164 decreases by a predetermined value or more with respect to the ground potential. However, the present invention is not limited to this. For example, a detecting means for detecting the charged potential of the original table 92 is provided, and the controller 170 removes the static electricity from the original table 92 according to the detection result of the detecting means. It may be determined whether or not to perform. In this case, not only the light source lighting control IC 161 but also the latch-up of, for example, the driving IC for the light source unit 54 and the mirror unit 53, the control IC for the CCD 57, and the control IC for the document conveying unit 120 can be prevented appropriately.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be applied to an image reading apparatus that reads an original and generates image data of the original, and an image output apparatus including the image reading apparatus.

52 First Reading Position 53 Mirror Unit 54 Light Source Unit 55 Imaging Lens 56 CCD Unit 57 CCD (Imaging Section)
90 Scanner unit 92 Document table 100 Image forming apparatus (image data output processing apparatus)
101 Document reading device (image reading device)
110 Image forming unit 111 Light source 120 Document transport unit 130 Light source control unit 131 Circuit board 132 Heat sink 134 Case 135 Lighting circuit 160 Step-up transformer 162 Oscillator 165 Driver 165a, 165b N channel transistor 170 Control unit 171 Ion generator 182c Fan 185 Ion Generating element 186a First duct 186b Second duct 163 Module A
167 Module B (overcurrent detector)
164 Module C
165 Driver (Emergency cut-off circuit)
168 Module D (potential difference detector)
166 Module E (Emergency cut-off circuit)
153 Switching FET
161 Light source lighting control IC

Claims (10)

A document table, a light source for irradiating light on the document placed on or conveyed on the document table, and reflected light emitted from the light source and reflected by the document, and converted into an electric signal An image reading apparatus including an imaging unit that generates image data of a document,
A circuit board having a semiconductor integrated circuit for controlling the operation of electrical components provided in the image reading apparatus;
An image reading apparatus comprising: an ion generating device that generates ions and discharges the generated document by ejecting the generated ions onto the document table. A switching element for switching the light source between a lighting state and a light-off state is provided,
The image reading apparatus according to claim 1, wherein the semiconductor integrated circuit controls an operation of the switching element. A step-up transformer that boosts the voltage applied to the primary coil and supplies the voltage to the light source from the secondary coil;
The switching element has a field effect in which a gate electrode is connected to the semiconductor integrated circuit, a drain electrode is connected to a power supply voltage source via a primary coil of the step-up transformer, and a source electrode is grounded via an electric resistance. A transistor,
The semiconductor integrated circuit controls the voltage applied to the gate electrode to switch the field effect transistor between a conduction state and a cutoff state, thereby switching the light source between a lighting state and a light-off state.
An overcurrent detection unit that outputs a detection signal corresponding to the potential of the source electrode to the semiconductor integrated circuit;
An emergency cutoff circuit that is provided in the semiconductor integrated circuit and switches the field-effect transistor to a cutoff state when the potential of the detection signal is a potential indicating an overcurrent;
A potential difference detection unit for detecting a potential difference between the potential of the detection signal and the ground potential;
When the potential difference detected by the potential difference detection unit exceeds a predetermined value that is set to a value that considers a predetermined safety factor with respect to the potential at which latch-up occurs in the semiconductor integrated circuit, the ion generator is controlled. The image reading apparatus according to claim 2, further comprising a control unit that ejects ions to the document table. Detection means for detecting the charge amount of the document table;
4. The apparatus according to claim 1, further comprising: a control unit that controls the ion generation device to inject ions onto the document table when the charge amount detected by the detection unit is equal to or greater than a predetermined value. The image reading apparatus according to claim 1.   5. The image reading apparatus according to claim 3, wherein the control unit stops the operation of the ion generation device during a period in which the document table is not neutralized. The platen is made of glass,
The image reading apparatus according to claim 1, wherein the ion generation device generates at least negative ions and ejects the negative ions onto the document table.   7. The image reading apparatus according to claim 1, wherein the ion generation device generates positive ions and negative ions and jets the positive ions and the negative ions onto the document table. The ion generator is
An ion generator that generates positive ions and negative ions;
A first duct for injecting positive ions and negative ions generated by the ion generator to the document table;
A second duct for discharging positive ions and negative ions generated by the ion generation unit to the outside of the image reading device;
A switching unit for switching the transfer destination of the positive ions and negative ions generated by the ion generation unit to either the first duct or the second duct,
When neutralizing the original platen, ions generated by the ion generation unit are jetted to the original platen via the first duct, and generated by the ion generation unit during a period when neutralization of the original platen is not performed. The image reading apparatus according to claim 7, further comprising a switching control unit that controls an operation of the switching unit so that ions are released to the outside of the image reading apparatus through the second duct. The semiconductor integrated circuit is disposed below the document table,
9. The image reading apparatus according to claim 1, wherein the ion generating apparatus ejects ions onto an upper surface of the document table. An image reading apparatus according to any one of claims 1 to 9,
Image forming processing for forming an image corresponding to the image data of the document generated by the image reading device on a recording material, image transmission processing for transmitting the image data to another device, and storing the image data in a storage medium An image data output processing apparatus, comprising: an output processing unit that performs any one or more of the image storage processes to be performed.

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