JP6884591B2 - Image reader and image forming device - Google Patents

Description

The present invention relates to an image reading device capable of reading an image of a document and an image forming device using the same.

In a conventional image reading device, a fixed reading in which a document reading unit uses a close contact image sensor (hereinafter, CIS: contact image sensor) to fix a document on a platen glass and move the CIS to scan, and automatic document transport. There is a document scanning device capable of scanning a document transported by an apparatus (hereinafter, ADF: auto document sensor). (See, for example, Patent Document 1.)

Published Japanese Patent Application Laid-Open No. 2015-61249

A flexible flat cable (hereinafter, FFC: flexible flat cable) is generally used as a cable connecting a movable reading unit using CIS and a control board. As a measure against noise caused by external static electricity on the FFC, a conductive member is added to the surface of the FFC. In the case of scanning in a low temperature and low humidity environment, when the original is continuously passed through the paper, static electricity may be generated due to the rubbing between the original and the reading glass, and the reading glass may be charged. Here, when the frame is made of metal and the frame is grounded, there is no problem because the electric charge generated in the reading glass is grounded through the frame. However, when the frame is made of resin, even if the resin frame is grounded, the electric charge generated on the reading glass is transmitted through the resin frame to the conductive foil on the surface of the FFC, and the conductive foil is charged. Sometimes. When the conductive member is charged, it affects the CIS and the image signal passing through the control substrate, which causes a problem that the image of the read image is deteriorated.

One aspect of the image reading device according to the present invention is a transporting unit that conveys a sheet, a transparent member that contacts the sheet conveyed by the conveying portion and guides the sheet, and light reflected from the sheet is transmitted through the transparent member. A reading unit that receives light and reads an image of a sheet, a flexible flat cable that is provided with a conductive member on the surface and is connected to the reading unit, a resin frame that supports the transparent member, and a frame that is provided on the frame. comprising a charge removing member for the said discharging member, when the reading unit is positioned at the reading position for reading an image of the sheet conveyed by the conveyance unit, and the conductive member and the frame body is proximate The static elimination member is provided at a position and is grounded.

According to the present invention, it is possible to prevent the FFC provided with the conductive member from being charged and causing image deterioration of the read image.

The perspective view of the image reading apparatus which concerns on embodiment of this invention. Sectional drawing of the image reading apparatus which concerns on embodiment of this invention. The schematic which shows the structure of the image formation engine which concerns on embodiment of this invention. An enlarged cross-sectional view of an image reader according to an embodiment of the present invention. The perspective view of the image reading apparatus which concerns on embodiment of this invention. The figure which shows the charge amount of FFC.

[Example]
Hereinafter, the image reading device and the image forming device according to the present disclosure will be described with reference to the drawings. FIG. 1 is an upward perspective view of the image reading unit 10, FIG. 2 is a main sectional view of the image reading device, and FIG. 3 is a schematic view showing a configuration of an image forming engine.

[overall structure]
First, the outline of the printer 100, which is an example of the image forming apparatus, will be described. The printer 100 is an electrophotographic laser beam printer. As shown in FIG. 1, the printer 100 includes a printer main body 70 and an image reading unit 10 (image reading device) mounted on the upper part of the printer main body 70. In the following, the sheet includes, in addition to plain paper, special paper such as coated paper, recording material having a special shape such as envelope and index paper, and plastic film and cloth for overhead projectors.

The printer main body 70 has an image forming engine 60 inside the housing 70A. As shown in FIG. 3, the image forming engine 60 includes an electrophotographic image forming unit PU and a fixing device 7. When the start of the image forming operation is commanded, the photosensitive drum 1 which is a photoconductor rotates, and the drum surface is uniformly charged by the charging device 2. Then, the exposure apparatus 3 modulates and outputs the laser beam based on the image data transmitted from the image reading unit 10 or an external computer, scans the surface of the photosensitive drum 1, and forms an electrostatic latent image. This electrostatic latent image is visualized (developed) by the toner supplied from the developing device 4 to become a toner image.

In parallel with such an image forming operation, a feeding operation of feeding a sheet loaded on a cassette or a manual feed tray (not shown) to the image forming engine 60 is executed. The fed sheet is conveyed in accordance with the progress of the image forming operation by the image forming unit PU. Then, the toner image supported on the photosensitive drum 1 is transferred to the sheet by the transfer roller 5. The toner remaining on the photosensitive drum 1 after the toner image transfer is recovered by the cleaning device 6. The sheet on which the unfixed toner image is transferred is delivered to the fixing device 7, sandwiched between roller pairs, and heated and pressurized. The sheet in which the toner is melted and fixed to the sheet and the image is fixed is discharged to the outside of the housing 70A by the discharge roller pair.

Further, the printer main body 70 is equipped with a control unit 80. The control unit 80 includes a central processing unit (CPU) that controls the printer 100 in an integrated manner, and a memory that stores programs, image information, and setting information executed by the CPU. The control unit 80 can control the image forming engine 60 to perform an image forming operation of forming an image on a sheet which is a recording medium.

The image forming engine 60 is an example of an image forming means capable of forming an image on a sheet as a recording medium, and an intermediate transfer method including an intermediate transfer body may be used instead of the above-mentioned direct transfer method. , Other mechanisms such as an inkjet method may be used.

[Image reader]
Next, the image reading unit 10 which is an example of the image reading device will be described. As shown in FIG. 2, the image reading unit 10 includes an ADF 11 that automatically feeds a document placed on a document tray 14, and a scanner unit 12 provided with a platen glass 30 and a scanning glass 23 (transparent member). And have. The ADF 11, which is an example of the sheet feeding device, is rotatably supported with respect to the scanner unit 12 by a hinge so that the platen glass 30 and the reading glass 23 can be opened. That is, the frame body of the image reading unit 10 is composed of a main body frame that constitutes the scanner unit 12 and an opening / closing frame that constitutes the ADF 11 and can be opened and closed with respect to the main body frame. The sheet used as the original may be a blank sheet or may have an image formed on one side or both sides. The platen glass 30 and the reading glass 23 may be shared by a single piece of glass.

As shown in FIG. 2, the ADF 11 includes a document tray 14 on which the document D1 is placed, a document transport section 15 for transporting the document D1 fed from the document tray 14, and an ejection tray 29 on which the document D1 is ejected. And have. The document transport section 15 has a document transport path (U turn path) 22 that is curved in a substantially U shape. The document transport section 15 includes a pickup roller 17, a separation roller 18, a separation pad 19, a document stopper 40, a document presence / absence sensor 41, a transport roller pair 43, a discharge roller pair 24, and a document edge sensor along the document transport path 42. 45 is arranged.

Sensor units 16 and 26 capable of reading image information from the document D1 are arranged in the ADF 11 and the scanner unit 12, respectively. The sensor unit 26 is an example of a reading unit. A close contact type image sensor (CIS) is used for the sensor units 16 and 26. The sensor units 16 and 26 include an LED array, a lens, and a sensor element as a light source. The LED array irradiates the image information surface of the document D1 with light, and the reflected light reflected on the image information surface is imaged on the sensor element through the lens. The sensor element photoelectrically converts the received light and outputs it as image data. In this way, the sensor units 16 and 26 read the image information of the document D1. The image data is output to the control unit 80 of the main body by the FFC 22 (FIGS. 4 and 5) which is a flexible flat cable described later.

Hereinafter, an operation (scanning operation) in which the image reading unit 10 reads image information from the document D1 while feeding the document D1 by the ADF 11 will be described. First, the operator places the document D1 on the document tray 14. At this time, the tip position of the document D1 is regulated by the document stopper 40, the document D1 is detected by the document presence / absence sensor 41, and the control unit 80 recognizes the existence of the document.

Then, when the operator instructs the start of scanning via an operation unit (not shown), the document stopper 40 is pushed down by the driving force supplied from the drive unit (not shown), and the document D1 is separated from the separation roller 18 by the pickup roller 17. It is conveyed to the separation part between the pads 19. Then, the document D1 is separated from other documents by the separation pad 19, and the uppermost document D1 is conveyed by the separation roller 18. The separated document D1 is conveyed along the document transfer path 42 by the transfer roller pair 43, and is conveyed toward the reading position by the sensor units 16 and 26. The document D1 comes into contact with the reading glass 23 near the reading position and is guided by the reading glass 23.

When the tip of the document D1 is detected by the document edge sensor 45, the sensor units 16 and 26 start reading the image information at the timing when the tip of the document D1 is conveyed by a predetermined amount from the detection position of the document edge sensor 45. To. The sensor unit 16 arranged in the scanner unit 12 reads image information from the first surface (front surface) of the document D1, and the sensor unit 26 arranged in the ADF 11 has a second surface (back surface) opposite to the first surface of the document D1. ) Read the image information. The document D1 that has passed the reading positions of the sensor units 16 and 26 is conveyed toward the discharge roller pair 24. Then, when the rear end portion of the document D1 is detected by the document edge sensor 45, the image information by the sensor units 16 and 26 is transmitted at the timing when the rear end portion of the document D1 is conveyed from the detection position of the document edge sensor 45 by a predetermined amount. Reading ends. Then, the document D1 is discharged to the discharge tray 29 by the discharge roller pair 24. Such a scanning operation is repeated until the document presence / absence sensor 41 detects that the document placed on the document tray 14 does not exist.

The image reading unit 10 can execute an operation (fixed reading operation) of reading image information from a document placed on the platen glass of the scanner unit 12. In this case, the image information is read from the document by moving the sensor unit 16 in the sub-scanning direction a (first direction) along the platen glass while the document is placed still on the platen glass.

[Detailed configuration of reader]
The detailed configuration of the reading unit will be described with reference to FIG. FIG. 4 is an enlarged cross-sectional view of the vicinity of the sensor unit 26 of FIG. FIG. 5 is a perspective view of the sensor unit 26 of FIG. Note that FIG. 5 does not show the reading glass 23, but shows the sensor unit 26 so as to be exposed.

The sensor unit 26 is housed inside a frame including an upper cover 25 and an exterior frame 20. The upper cover 25 and the outer frame 20 are made of resin, and are specifically made of PC-ABS. The reading glass 23 is supported by the exterior frame 20. The sensor unit 26 is supported by the shaft 31 so as to be movable in the sub-scanning direction a. The FFC 22 is connected to the read sensor unit 26. The image data output from the sensor unit 26 is transmitted to the control unit 80 provided in the printer main body 70 through the FFC 22. The FFC 22 is provided with a metal foil 22a, which is an example of a conductive member, in a part of the FFC in the width direction. The metal foil 22a is provided as a noise countermeasure against external static electricity on the FFC 22. The FFC 22 is arranged so that a curved portion W is provided between the end portion on the sensor unit 26 side and the end portion on the printer main body 70 side. The metal foil 22a is provided on the outside of the curved portion W. When the sensor unit 26 is located at the reading position, the metal leaf 22a provided on the curved portion W is close to the exterior frame 20.

[Structure of static eliminator]
When the document D1 is continuously scanned, an electric charge E is generated by rubbing between the document D1 and the reading glass 23. As shown in FIG. 4, the generated electric charge E is transmitted to the reading glass 23, the upper cover 25, and the outer frame 20 as shown by the arrows. In the figure, the electric charge E is schematically shown as passing through the inside of the substance, but the electric charge E is actually transmitted on the surface of the member. If the upper cover 25 and the outer frame 20 are made of a conductive metal material, the electric charge E can be released by grounding some part of the metal material. However, when the upper cover 25 and the outer frame 20 are molded of resin as in the present embodiment, there is a problem that the metal foil 22a is charged. It is considered that this is because the electric charge E is transmitted on the surface of the resin material and flies from the exterior frame 20 to the metal foil 22a at the curved portion W where the metal foil 22a and the exterior frame 20 are close to each other. When the metal leaf 22a of the FFC 22 is charged, it affects the image data transmitted through the FFC, resulting in defective image data. This problem occurs especially in a low temperature and low humidity environment. Further, this problem occurs when the distance between the metal foil 22a and the exterior frame 20 is close (for example, when they are close to each other within 10 mm).

In order to solve this problem, in the present embodiment, an aluminum tape 21 which is an example of a static elimination body is provided on the surface of the exterior frame 20 facing the metal foil 22a of the curved portion W. When the sensor unit 26 is located at the reading position, the distance between the metal foil 22a and the aluminum tape 21 is larger than 0 mm and 10 mm or less. The aluminum tape 21 is provided with a conductive double-sided tape on one surface, and is adhered to the exterior frame 20 by the double-sided tape. A metal plate may be used as the static eliminator instead of the aluminum tape. The aluminum tape 21 is fastened to the shaft holding member 27 for fixing the shaft 31 with screws 28. The shaft holding member 27 is an example of a shaft fixing member. The shaft holding member 27 and the screw 28 are provided of a conductive metal, and are grounded to the ground of the main body of the apparatus by a ground wire (not shown). By doing so, the electric charge E transmitted to the exterior frame 20 is transmitted to the aluminum tape 21, the shaft holding member 27, and the ground wire and falls to the ground of the main body of the apparatus. It is possible to suppress charging. Then, by suppressing the charging of the exterior frame 20, it is possible to prevent the metal foil 22a of the FFC 22 from being charged and causing image defects in the read image.

FIG. 6 shows the transition of the charge amount of the FFC 22 between the configuration in which the metal foil 22a which is a static elimination member is used for the exterior frame 20 as in the present embodiment and the configuration in which the static elimination member is not provided. The horizontal axis is the number of sheets continuously passed through the document D, and the other axis is the charge amount of FFC22.

As is clear from FIG. 6, the configuration using the metal foil 22a can suppress an increase in the amount of charge of the FFC 22.

In the present embodiment, the aluminum tape 21 is provided on a part of the surface of the exterior frame 20 facing the metal foil 22a. Specifically, in the main scanning direction (second direction) orthogonal to the sub-scanning direction a, the sensor unit 26 to which the FFC 22 is connected extends from one side toward the center. The aluminum tape 21 is not provided on the other end side of the sensor unit 26 in which the FFC 22 does not exist. By doing so, it is possible to reduce the cost as compared with the case where the entire exterior frame is made of a metal frame or a structure having conductivity. Further, the aluminum tape 21 is grounded by being connected to the shaft holding member 27 of the shaft 31 that supports the sensor unit 26. The shaft holding member 27 is made of metal. This is intended to be firmly fixed to the frame so that the sensor unit 26 does not shake when the sensor unit 26 moves on the shaft 31. Further, the shaft 31 is made of metal in consideration of rubbing against the sensor unit 26, and the shaft holding member 27 is grounded in order to eliminate static electricity from the shaft 31. In this way, by using the shaft holding member 27 that was originally grounded, it is possible to reduce the cost as compared with the case where a metal member dedicated to grounding is provided for grounding the aluminum tape 21. The aluminum tape 21 may be connected to the shaft 31 instead of the shaft holding member 27.

In the present embodiment, the electrophotographic image forming apparatus has been described as an example, but it can also be applied to an image reading apparatus such as a flatbed scanner having no image forming portion.

In the present embodiment, although the resin exterior frame is described, metal is used as a part of the exterior frame at a position (a position not facing the FFC 22) where the problem according to the present invention does not occur. You may.

20 Exterior frame 21 Static eliminator 22 FFC
23 Reading glass (transparent member)
26 Sensor unit (reading unit)
27 Shaft holding member (shaft fixing member)

Claims (8)

The transport unit that transports the sheet and
A transparent member that comes into contact with the sheet conveyed by the conveying unit and guides the sheet,
A reading unit that receives the light reflected from the sheet through the transparent member and reads the image of the sheet.
A flexible flat cable provided with a conductive member on the surface and connected to the reading unit,
A resin frame that houses the reading unit inside,
A static elimination member provided on the frame body is provided.
The discharging member, when the reading unit is positioned at the reading position for reading an image of the sheet conveyed by the conveying unit, disposed at a position between the conductive member and the frame body are close,
An image reading device characterized in that the static elimination member is grounded. The image reading device according to claim 1, wherein the flexible flat cable has a curved portion when the reading unit is located at the reading position, and the conductive member is provided at the curved portion. The conductive member is provided on the outside of the curved portion, and is provided on the outside of the curved portion.
The static elimination member is characterized in that it is provided on the surface of the frame body facing the conductive member when the reading unit is positioned at a reading position for reading an image of a sheet conveyed by the conveying unit. The image reading device according to claim 2. The image reading device according to claim 2 or 3 , wherein when the reading unit is located at the reading position, the distance between the conductive member and the static elimination member is greater than 0 mm and 10 mm or less. The reading unit is provided so as to be movable.
The moving direction of the reading unit is defined as the first direction, and the direction orthogonal to the first direction is defined as the second direction.
The flexible flat cable is provided on one side of the center of the reading unit in the second direction.
The image reading device according to any one of claims 1 to 4 , wherein the static elimination member is provided so as to extend between the one side and the center in the second direction. A shaft that movably supports the reading unit is provided.
A shaft fixing member for fixing the shaft is provided.
The image reading device according to any one of claims 1 to 5 , wherein the static elimination member is grounded via the shaft fixing member. A shaft that movably supports the reading unit is provided.
The image reading device according to any one of claims 1 to 5 , wherein the static elimination member is grounded via the shaft. The image reading device according to any one of claims 1 to 7 , an image forming unit that forms an image based on an image read by the image reading device, and an image forming unit.
An image forming apparatus comprising.

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