JP6660026B2 - Image reading apparatus and image forming apparatus provided with the image reading apparatus - Google Patents

Description

  The present invention relates to an image reading device and an image forming apparatus provided with the image reading device.

  2. Description of the Related Art Conventionally, a technique has been proposed in which air is jetted between a contact glass and a document in order to remove foreign matters such as dust and dust on a contact glass of an image reading apparatus (for example, see Patent Document 1). This image reading apparatus has a fan for supplying air and a nozzle for ejecting the air supplied from the fan. The nozzles are provided over the entire area in the sheet width direction (a direction orthogonal to the document conveyance direction) upstream of the image reading position in the document conveyance direction. The timing of air injection by the fan is controlled by the controller. When the leading edge of the document reaches the reading position, the controller activates the fan to eject air, and stops the operation of the fan after the trailing edge of the document passes the reading position to stop the air ejection.

JP 2006-276131A

  In the image reading apparatus disclosed in Patent Document 1, air is blown between the contact glass and the document when the document passes the reading position. For this reason, there is a problem that the document is wavy due to a slight change in the air jet flow rate while the document is passing the reading position, and the accuracy of reading the image of the document is reduced.

  The present invention has been made in view of such a point, and an object of the present invention is to efficiently remove foreign matter on a contact glass without lowering the image reading accuracy of a document.

  An image reading device according to an aspect of the present invention is disposed to face an upper surface of a contact glass, and has a facing member that forms a gap through which a document passes between the upper surface and a plurality of documents facing the gap. A document feeding unit for feeding a document at a predetermined time interval, an image reading unit for reading an image of a document passing a reading position on the contact glass, and an air ejecting unit for supplying air to the upper surface of the contact glass are provided. .

  The air ejecting unit includes a micro blower that injects air, a duct having one end connected to an air outlet of the macro blower, and the other end communicating with the upstream end of the gap in the document conveying direction, and a rear end of the document. A blower control unit that controls the operation of the micro-blower so that air is injected by the micro-blower during a sheet interval before the end of the document passes through the reading position and before the next document is supplied to the gap. And

  An image forming apparatus according to another aspect of the present invention includes the above image reading device.

  ADVANTAGE OF THE INVENTION According to this invention, the foreign material on a contact glass can be removed efficiently, without lowering the image reading precision of a document.

FIG. 1 is a schematic diagram illustrating an image forming apparatus including an image reading device according to an embodiment. FIG. 2 is an enlarged view showing an air jet unit provided in the image reading apparatus and its periphery in an enlarged manner. FIG. 3 is a sectional view taken along line III-III of FIG. FIG. 4 is a side view showing the air ejecting unit as seen from the front-back direction (the direction orthogonal to the document feeding direction). FIG. 5 is a plan view showing the air injection unit as viewed from above. FIG. 6 is a block diagram illustrating a configuration of a control system of the air injection unit. FIG. 7 is a flowchart showing the contents of image reading control and air ejection control executed by the controller.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments.

  FIG. 1 illustrates a multifunction peripheral Y including an image reading apparatus X according to the embodiment. The MFP Y includes an image reading unit 1, an ADF (document feeding unit) 2, an image forming unit 3, a controller 4, an operation unit 5 (see FIG. 6), and the like. An image reading device X is configured by the image reading unit 1 and the ADF 2. In the following description, the front side and the rear side mean the front side and the back side in the direction perpendicular to the paper surface of FIG. 1, and the left side and the right side mean the left side and the right side when the MFP Y is viewed from the front side. I do.

  The multifunction peripheral Y is an electrophotographic image forming apparatus that forms an image on a sheet based on image data read by the image reading unit 1 or image data input from an information processing device such as an external personal computer. .

  The image forming unit 3 includes a paper feed cassette 30, a photosensitive drum 31, a charging device 32, a developing device 33, a toner container 34, a transfer roller 35, a static eliminator 36, a fixing roller 37, a pressure roller 38, and a discharge tray. 39 and the like.

  Then, the image forming section 3 forms an image on the paper supplied from the paper feed cassette 30 in the following procedure. Specifically, first, the photosensitive drum 31 is uniformly charged to a predetermined potential by the charging device 32. Next, the surface of the photosensitive drum 31 is irradiated with light based on image data by a laser scanning unit (LSU) not shown. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 31. The electrostatic latent image on the photosensitive drum 31 is developed by the developing device 33 as a toner image. The developing device 33 is supplied with toner from the toner container 34.

  The toner image formed on the photosensitive drum 31 is transferred to a sheet by the transfer roller 35. Thereafter, the toner image transferred to the sheet is heated and fixed by the fixing roller 37 when the sheet passes between the fixing roller 37 and the pressure roller 38. The potential of the photosensitive drum 31 is eliminated by the neutralization device 36.

  The image reading unit 1 includes a contact glass 11, a reading unit 12, mirrors 13 and 14, an optical lens 15, and a CCD sensor 16.

  The contact glass 11 is mounted on an upper wall portion of the scanner housing C that forms an outer wall of the image reading unit 1. The contact glass 11 includes a first contact glass 11a used when reading an image by a sheet-through method described later and a second contact glass 11b used when reading an image using a fixed method. The first contact glass 11a has a rectangular plate shape that is long in the front-rear direction (the direction orthogonal to the document conveyance direction), and is mounted on the left end of the upper wall of the scanner housing C. The second contact glass 11b has a rectangular plate shape that is long in the left-right direction, and is disposed on the right side of the first contact glass 11a.

  The reading unit 12 is housed in a scanner housing C and has an LED light source 121 and a mirror 122. The reading unit 12 is configured to be movable in the left-right direction (sub-scanning direction) by a driving mechanism (not shown) using a driving motor such as a stepping motor. When the reading unit 12 is moved in the sub-scanning direction by the drive motor, light emitted from the LED light source 121 to the contact glass 11 is scanned in the sub-scanning direction.

  The mirror 122 reflects reflected light from the LED light source 121 when the document P passing through the reading position 12A is irradiated with light, toward the mirror 13. Then, the light reflected by the mirror 122 is guided to the optical lens 15 by the mirrors 13 and 14. The mirrors 13 and 14 are mounted on a carriage (not shown) and move in the sub-scanning direction at half the speed of the reading unit 12 during a reading operation by a sheet fixing method described later.

  The optical lens 15 condenses the incident light and causes the light to enter the CCD sensor 16. The CCD sensor 16 converts reflected light from the original image into analog image data by photoelectrically converting the light and outputs the analog image data to the controller 4.

  The controller 4 controls the entire operation of the image reading apparatus X, and is composed of a microcomputer having a CPU 4a, a ROM 4b, and a RAM 4c (see FIG. 6). The controller 4 creates digital data of the document image based on the analog image data received from the CCD sensor 16 and stores the digital data in the ROM 4b.

  The ADF 2 is an automatic document feeder including a document feed tray 21, a plurality of transport rollers 22, a guide member 23, and a discharge tray 24. The ADF 2 can be opened and closed with respect to the contact glass 11.

  The ADF 2 supplies and conveys the document P set on the document feed tray 21 to the reading position 12A on the first contact glass 11a at a predetermined time interval by driving each of the conveying rollers 22 by a motor (not shown). I do. The document P that has passed the reading position 12A is discharged to the discharge tray 24.

  A guide member (opposing member) 23 for guiding the document P passing through the reading position 12A is provided at a portion of the document pressing surface of the ADF 2 facing the first contact glass 11a. The guide member 23 is a rectangular plate-shaped member extending in the front-rear direction, and is also used as a white reference plate for shading correction. At the four corners of the guide member 23, columnar bosses 23a (see FIG. 2) are protruded. When the ADF 2 is closed, the boss 23a abuts on the upper surface of the image reading unit 1 (scanner housing C), so that a gap for document passage is secured between the guide member 23 and the first contact glass 11a. You.

  As a method for reading an original image by the image reading apparatus X, there are two types of methods, a sheet-through method and a fixed method. In the sheet-through system, the reading unit 12 is kept stationary below the reading position 12A on the first contact glass 11a, and in this state, the document P is moved by the ADF 2 into the gap between the guide member 23 and the first contact glass 11a. Supply and transport toward. Then, the image of the document P is read by moving and transporting the document P from one side in the sub-scanning direction to the other side with respect to the reading position 12A. On the other hand, in the image reading operation by the sheet fixing method, the image of the document P is read by moving the reading unit 12 from one side in the sub-scanning direction to the other side in a state where the document P is fixed on the second contact glass 11b. In the sheet fixing system, the ADF 2 simply functions as a document pressing member.

  As shown in FIGS. 2 and 3, an air injection unit 50 is housed in the scanner housing C. In the present embodiment, two air injection units 50 are provided as an example. The two air jet units 50 are arranged in the scanner housing C side by side in the front-rear direction. Each air ejecting section 50 ejects air toward a gap between the guide member 23 and the first contact glass 11a at the time of reading an image by the sheet-through method, so that foreign matter (dust and the like) on the upper surface of the first contact glass 11a. Is removed by wind pressure. Since the configuration of the front and rear air injection units 50 is the same, the following description will be given without distinguishing the front and rear air injection units 50 unless otherwise specified.

  Each air injection unit 50 has a micro blower 51 and a duct 52. The micro blower 51 blows air by vibrating a plate-shaped vibration plate with a piezoelectric element. The micro blower 51 is fixed to the inner surface of the left side wall of the scanner housing C. The duct 52 is connected to an air outlet 51 a of the micro blower 51.

  As shown in FIGS. 4 and 5, the duct 52 has a duct body 52a and a duct tip 52b.

  The duct body 52a has a base end connected to the air outlet 51a of the micro blower 51. The duct main body 52a is a flat duct part whose width in the front-rear direction increases from the base end side toward the front end side (from the upstream side to the downstream side in the air supply direction). The duct main body 52a is inclined upward toward the right side. The distal end of the duct body 52a penetrates through the upper wall of the scanner housing C and is located in the gap between the guide member 23 and the first contact glass 11a. The width in the front-rear direction of the distal end (downstream end) of the duct main body 52a is substantially half the width in the front-rear direction of the gap between the guide member 23 and the first contact glass 11a.

  The duct tip 52b is connected to the duct body 52a. The channel width in the front-rear direction of the duct distal end portion 52b is constant without changing from the base end side to the distal end side. The vertical channel width of the duct tip 52b gradually decreases from the base end toward the tip. That is, the duct distal end portion 52b has a nozzle shape in which the flow path cross-sectional area decreases from the base end side toward the distal end side.

  The air outlet of the duct tip 52b includes a plurality of ventilation holes 52c arranged in the front-rear direction as shown in FIG. The plurality of ventilation holes 52c are formed such that the hole diameters at both ends in the front-rear direction of the duct tip 52b are larger than those at the center.

  An upper surface 52e (see FIGS. 2 and 4) of the duct tip 52b is an inclined surface whose height from the first contact glass 11a decreases from the upstream side to the downstream side in the document conveying direction. The upper surface 52e of the duct tip 52b functions as a guide surface for guiding the document P supplied and conveyed by the ADF 2 to the gap between the guide member 23 and the first contact glass 11a.

  Next, a configuration of a control system of the air injection unit 50 will be described with reference to FIG. This control system has a controller 4. The controller 4 is electrically connected to the operation unit 5 and the micro blower 51. The operation unit 5 is configured by, for example, a touch-type liquid crystal panel. The user can set the number of documents P to be read by the image reading unit 1 and the image reading method (sheet-through method or sheet fixing method) through the operation unit 5. The operation unit 5 converts the information set by the user into a signal and transmits the signal to the controller 4. The controller 4 executes the image reading control and the air injection control by the micro blower 51 based on the signal from the operation unit 5.

  An example of the image reading control and the air ejection control in the controller 4 will be described with reference to FIG.

  In step S1, it is determined whether or not there is an image reading request based on a signal from the operation unit 5. If the determination is NO, the process returns. If the determination is YES, the process proceeds to step S2.

  In step S2, it is determined whether or not the image reading request is based on the sheet-through method. If this determination is NO, the process proceeds to step S7, while if YES, the process proceeds to step S3.

  In step S3, the micro blower 51 is operated to inject air into the gap between the guide member 23 and the first contact glass 11a for a predetermined time (for example, 0.1 to 0.5 seconds).

  In step S4, the document P is supplied and transported by the ADF 2 toward the gap between the guide member 23 and the first contact glass 11a.

  In step S5, it is determined whether or not the trailing edge of the document P has passed the reading position 12A. If this determination is NO, the process of step S5 is executed again. Proceed to S6.

  In step S6, the set number of sheets set by the user through the operation unit 5 is recognized based on the signal from the operation unit 5, and it is determined whether or not the image reading operation of the set number of originals P has been completed. Then, if this determination is NO, the process returns to step S3, while if YES, the image reading operation ends and returns.

  In step S7, to which the operation proceeds when the determination in step S2 is NO, an image reading operation by a fixed reading method is executed, and thereafter, the process returns.

  As described above, when there is an image reading request of the document P by the sheet-through method (when the determination in step S2 is YES), the controller 4 passes the rear end of the document P through the reading position 12A. After that, in the sheet interval time before the next original P is supplied and conveyed to the gap between the guide member 23 and the first contact glass 11a (from the determination of YES in step S5 to the execution of step S4, the original P Until the tip of the micro-blower reaches the gap, the air injection by the micro-blower 51 is executed (step S3).

  As a result, the foreign matter on the first contact glass 11a is blown by the wind pressure of the air blown from the micro blower 51 during the sheet interval after the image reading of the document P is executed and before the image reading of the next document P is executed. Can be skipped and removed.

  Here, when a rotary fan is used as the air supply source, the air is continuously injected by the rotation of the fan, so that the fan rotates by inertia even after issuing a stop command to the fan. Therefore, the air ejection cannot be completely completed within the sheet interval, and air is supplied from the fan into the gap even while the document P is passing through the reading position 12A. As a result, the document P may be wavy by the wind pressure and the image reading accuracy may be reduced.

  On the other hand, in the present embodiment, the micro-blower 51 using the piezoelectric element is used as the air supply source, so that the air injection by the air supply source can be surely terminated within the paper interval. Therefore, it is possible to prevent the document P from waving due to the supply of air into the gap while the document P is passing through the reading position 12A.

  Further, by using the micro blower 51, air can be instantaneously injected at a higher speed than when a fan is used. Therefore, the foreign matter on the first contact glass 11a can be surely removed by vigorously blown off by the jet air flow.

  The downstream end of the duct 52 in the air supply direction (duct end 52b) has a shape that is long in the front-rear direction. Therefore, the air flow jetted by the micro blower 51 can be supplied in a curtain shape to the upper surface of the first contact glass 11a, and the foreign matter on the first contact glass 11a can be blown off evenly by the jet air flow.

  When the duct tip 52b is formed long in the front-rear direction in this way, the distance from the micro-blower 51 is shortest at the center in the front-rear direction of the duct tip 52b, while the distance from the micro-blower 51 is long at both ends. Become. For this reason, the flow velocity of the air blown out from the duct tip 52b is not uniform between the center and both ends in the front-back direction, and as a result, the air volume of the air blown out from the duct 52 is reduced in the center and both ends in the front-back direction. It may not be uniform between the parts.

  On the other hand, in the present embodiment, the air outlet of the duct tip 52b is constituted by a plurality of ventilation holes 52c, and the diameter of the ventilation holes 52c at both ends in the front-rear direction of the duct tip 52b is larger than the diameter of the hole at the center. I made it bigger. Thereby, the air volume of the air blown out from the duct tip 52b can be made uniform in the front-rear direction.

  The upper surface 52e of the duct tip 52b is formed such that the height from the upper surface of the first contact glass 11a decreases from the upstream side to the downstream side in the document conveying direction. The upper surface 52e of the duct tip 52b functions as a guide surface for guiding the document P to a gap between the guide member 23 and the first contact glass 11a. Thereby, the posture of the document P entering the gap can be stabilized, and the reading accuracy of the document image by the image reading unit 1 can be improved.

  The duct tip 52b has a nozzle shape in which the cross-sectional area of the flow path decreases toward the tip. Thereby, the flow velocity of the air blown out from the duct tip 52b can be increased as much as possible. Therefore, the effect of cleaning the upper surface of the first contact glass 11a by the jet airflow can be improved.

<< Other embodiments >>
In the above embodiment, the MFP Y is described as an example of the image forming apparatus on which the image reading apparatus X is mounted. However, the present invention is not limited to this, and the image forming apparatus may be a copier, a facsimile, or the like. It may be.

  As described above, the present invention is useful for an image reading apparatus and an image forming apparatus including the image reading apparatus.

P Document X Image reading device Y Multifunction machine (image forming device)
1 image reading unit 2 ADF (document feeding unit)
4 Controller (blower control unit)
11a First contact glass 12A Reading position 50 Air injection unit 51 Micro blower 52 Duct 52b Duct tip (downstream end of duct)
52c Vent 52e Top surface of duct tip

Claims (3)

An opposing member disposed opposite to the upper surface of the contact glass to form a gap between the upper surface and the document, and a document feeder for feeding a plurality of documents toward the gap at predetermined time intervals An image reading device, comprising: an image reading unit that reads an image of a document passing a reading position on the contact glass; and an air ejecting unit that ejects air onto an upper surface of the contact glass.
The air injection unit,
A micro-blower as an air supply,
One end is connected to the ventilation hole of the micro blower, the other end is located in the gap between the contact glass and the facing member in the gap, a duct,
After the rear end of the document has passed through the reading position, the operation of the micro-blower is controlled so that the air blow by the micro-blower is executed during the sheet interval before the next document is supplied to the gap. Having a blower control unit ,
The upper surface of the downstream end of the duct in the air supply direction is formed so that the height from the upper surface of the contact glass decreases from the upstream side to the downstream side in the document conveying direction, and that acts as a guide surface for guiding in the gap, the image reading apparatus. The image reading device according to claim 1 ,
An image reading device, wherein a downstream end of the duct in the air supply direction has a nozzle shape in which a flow path cross-sectional area decreases toward the downstream side. Image forming apparatus including an image reading apparatus according to claim 1 or 2, wherein.

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