IMAGE READING APPARATUS AND IMAGE FORMING SYSTEM

An image reading apparatus reads an image of a sheet conveyed from an image forming apparatus. The image reading apparatus includes a transparent member including a first surface disposed on a first side on which the sheet is conveyed and a second surface disposed on a second side opposite to the first side, an image reading portion disposed on the second side and configured to read the image of the sheet at a reading position through the transparent member, an elastic member disposed to abut against the second surface of the transparent member and configured to press the transparent member toward the first side, and a guide disposed upstream of the reading position and configured to guide the sheet to the reading position. A downstream end of the guide contacts with the first surface of the transparent member and presses the transparent member toward the second side.

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

The present disclosure relates to an image reading apparatus and an image forming system.

Description of the Related Art

Conventionally, in order to improve image quality, an inspection apparatus incorporating an image reading apparatus has been devised as a device configured to read an image output from an image forming apparatus such as a copying machine and to detect the presence or absence of a defect in the image. The inspection apparatus reads an image data printed on a sheet while conveying a recording material (hereinafter referred to as a sheet) such as a sheet of paper on a reading glass. Further, Japanese Patent Application Laid-Open No. H11-69043 discloses an image reading apparatus in which a guide configured to introduce a sheet is provided on the upstream side of the reading glass in the sheet conveyance direction in order to smoothly pass the sheet onto the reading glass.

However, if there is a gap between the reading glass and the image reading apparatus, a foreign substance such as paper dust and dirt may enter through the gap. When the foreign substance adheres to a back side of the reading glass or a sensor of the image reading apparatus, the foreign substance is included as noise in an image data read by the image reading apparatus. Therefore, good image data cannot be obtained. To this end, it is conceivable to arrange an elastic member such as a sponge made of a foamed material for preventing intrusion of foreign substance in the gap between the reading glass and the image reading apparatus. By disposing the sponge in a squeezed state between the reading glass and the image reading apparatus, the intrusion path of the foreign substance can be blocked.

However, the reaction force of the squeezed sponge deflects the reading glass toward an opposed member. When the reading glass is deflected, a gap between the reading glass and the opposed member becomes smaller than a set distance. Therefore, a focus position of the image reading apparatus is shifted, which causes an issue of not being able to obtain good reading data.

SUMMARY OF THE DISCLOSURE

This disclosure improves image reading performance by reducing deflection of the reading glass.

An image reading apparatus configured to read an image of a sheet conveyed from an image forming apparatus configured to form the image on the sheet, the image reading apparatus comprising: a conveyance portion configured to convey the sheet in a conveyance direction; a transparent member including a first surface disposed on a first side on which the sheet is conveyed by the conveyance portion and a second surface disposed on a second side opposite to the first side; an image reading portion disposed on the second side with respect to the transparent member and configured to read the image of the sheet through the transparent member; an elastic member disposed to abut against the second surface of the transparent member on the second side and configured to press the transparent member toward the first side; and a guide disposed upstream of a reading position where the image reading portion reads the image of the sheet with respect to the conveyance direction and configured to guide the sheet conveyed by the conveyance portion to the reading position, wherein the guide is provided so that a downstream end of the guide with respect to the conveyance direction contacts with the first surface of the transparent member and presses the transparent member toward the second side.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will be described in exemplary detail with reference to the drawings below. However, the dimensions, materials and shapes of the components described in the embodiments should be appropriately changed according to the configuration of the apparatus to which the disclosure is applied and various conditions, and the scope of the disclosure is not limited to the following embodiments.

FIG. 1is a view showing an image forming system100. The image forming system100includes a printer101, an inspection apparatus (an image reading apparatus)102, and an output sheet sorting device (hereinafter referred to as a sorter)103. The printer101is an image forming apparatus configure to form an image on a sheet (recording material) P. The inspection apparatus102is connected to the printer101downstream of the printer101with respect to a conveyance direction CD of the sheet P. The sorter103is connected to the inspection apparatus102downstream of the inspection apparatus102with respect to the conveyance direction CD of the sheet P.

The printer101is a four-color full-color printer using an electrophotographic process. The printer101forms an image on the sheet P based on an image signal inputted to a control unit (not shown) from an information terminal (not shown) such as a personal computer (not shown) or an external device (not shown) such as an image reader (not shown), and discharges the sheet P on which the image is formed. The sheet P is a recording material on which an image is formed with toner. The sheet P includes, for example, plain paper, cardboard, transparencies, coated paper, and label paper. An operator operates the printer101through an operation portion21.

The printer101has four image forming portions11Y,11M,11C and11K provided side by side. The image forming portion11Y forms a yellow (Y) toner image. The image forming portion11M forms a magenta (M) toner image. The image forming portion11C forms a cyan (C) toner image. The image forming portion11K forms a black (K) toner image. Laser scanner units3Y,3M,3C, and3K as exposure apparatuses are arranged in the upper portions of the image forming portions11Y,11M,11C, and11K, respectively. The image forming portions11Y,11M,11C and11K are provided with electrophotographic photosensitive drums1Y,1M,1C and1K as image bearing members, chargers2Y,2M,2C and2K, and developing units4Y,4M,4C and4K, respectively. The image forming portions11Y,11M,11C and11K further have drum cleaners7Y,7M,7C and7K, respectively.

An intermediate transfer belt50is disposed below the image forming portions11Y,11M,11C and11K. The intermediate transfer belt50is stretched over a drive roller51, a tension roller52and a secondary transfer inner roller53, and is rotated in a direction indicated by an arrow R. The primary transfer rollers6Y,6M,6C, and6K are disposed opposite to the electrophotographic photosensitive drums1Y,1M,1C, and1K, respectively, via the intermediate transfer belt50. The image forming portions11Y,11M,11C and11K have substantially the same structure except for the color of the toner contained in the developing units4Y,4M,4C and4K.

The chargers2Y,2M,2C, and2K uniformly charge surfaces of the electrophotographic photosensitive drums1Y,1M,1C, and1K, respectively. The laser scanner units3Y,3M,3C, and3K expose the uniformly charged surfaces of the electrophotographic photosensitive drums1Y,1M,1C, and1K according to image signals of respective colors to form electrostatic latent images. The developing units4Y,4M,4C, and4K develop the electrostatic latent images formed on the surfaces of the electrophotographic photosensitive drums1Y,1M,1C, and1K with toners of respective colors to form toner images of yellow, magenta, cyan, and black. The yellow, magenta, cyan and black toner images are transferred on the intermediate transfer belt50by the primary transfer rollers6Y,6M,6C and6K and superimposed on top of one another.

On the other hand, sheets P are fed one by one from a cassette24and conveyed through a conveyance path13to a secondary transfer nip portion15formed between the intermediate transfer belt50and a secondary transfer roller14at a predetermined control timing. The toner images of the four colors on the intermediate transfer belt50are collectively transferred to a sheet P by the secondary transfer nip portion15. A transfer residual toner remaining on the intermediate transfer belt50after the secondary transfer is removed from the surface of the intermediate transfer belt50by a belt cleaner19. The sheet P on which the toner image is transferred is conveyed to a fixing device16. The fixing device16heats and pressurizes the sheet P to fix the toner image on the sheet P. A sheet P on which a full color image is formed is discharged from the printer101by a pair of discharge rollers17.

The sheet P discharged from the printer101is delivered to the inspection apparatus102connected downstream of the printer101. The inspection apparatus102is a device configured to detect the presence/absence of abnormality of print information of the sheet P discharged from the printer101. The inspection apparatus102has a first image reading apparatus202configured to read an image formed on one side of the sheet P and a second image reading apparatus204configured to read an image formed on the other side of the sheet P. First, a sheet P on which reference images are formed is conveyed to the inspection apparatus102. The first image reading apparatus202and the second image reading apparatus204read the reference images formed on the sheet P, and register (save) the images as the reference images in a computer210connected to the inspection apparatus102.

Thereafter, the inspection apparatus102reads the images of the sheet P conveyed from the printer101by the first image reading apparatus202and the second image reading apparatus204. The computer (an inspection portion)210performs image inspection by comparing the read images with the reference images. The image information of the read sheet P is compared with the image information of the reference images registered in advance, and an existence of a difference between the images formed by the printer101and the reference images is determined. Based on the difference between the image information of the images formed by the printer101and the image information of the reference images, it is determined whether or not the image formed on the sheet P by the printer101is an abnormal image.

The sheet P discharged from the inspection apparatus102is conveyed to the sorter103. In a case in which the inspection apparatus102determines that there is no abnormality in the image formed on the sheet P discharged from the printer101, the sorter103discharges the sheet P to a tray501. In a case in which the inspection apparatus102determines that there is an abnormality in the image formed on the sheet P discharged from the printer101, the sorter103discharges the sheet P to a tray502. As a result, a series of image forming, inspection processing and sorting processing by the image forming system100is completed.

FIG. 2is a cross-sectional view of the first image reading apparatus202and the second image reading apparatus204. A conveyance of the sheet P (not shown inFIG. 2) in the first image reading apparatus202and the second image reading apparatus204disposed in the inspection apparatus102will be described with reference toFIG. 2. The printer101(not shown inFIG. 2) is disposed on the right side ofFIG. 2, and the sorter103(not shown inFIG. 2) is disposed on the left side ofFIG. 2. There is a floor (not shown inFIG. 2) on the lower side ofFIG. 2and a ceiling (not shown inFIG. 2) on the upper side ofFIG. 2. The sheet P is conveyed in the conveyance direction CD.

The inspection apparatus102has an inlet lower guide221and an inlet upper guide222. The inlet lower guide221and the inlet upper guide222suppress the fluttering of the sheet P caused by the conveyance of the sheet P entering the inspection apparatus102. The material of the inlet lower guide221and the inlet upper guide222is SUS 420 CP. A polishing process is applied to the contact surfaces of the inlet lower guide221and the inlet upper guide222with the sheet P to improve the surface properties of the contact surfaces so as not to damage the sheet P. An inlet sensor223detects the sheet P entering the inspection apparatus102. A reflection type photosensor is used as the inlet sensor223.

Based on a timing at which the inlet sensor223detects the sheet P entering the inspection apparatus102, a timing at which the first image reading apparatus202reads the image formed on the one side of the sheet P is controlled. Further, if it is determined based on the detection result of the inlet sensor223that there is an abnormality in the conveyance of the sheet P, a jam processing of the sheet P is executed.

A first conveyance roller pair201comprises a conveyance roller211having a steel shaft211aattached with two pieces of silicone rubber211bhaving an outer diameter of 20 mm, and a rotatable member212made of POM resin arranged at a position corresponding to each piece of the silicone rubber211b. The POM resin is a polyoxymethylene resin or a polyacetal resin. The conveyance roller211is rotated by a rotation drive transmitted from a driving motor (not shown) to the end of the conveyance roller211via a timing belt (not shown).

The rotatable member212is rotatably supported on an axis. The rotatable member212is urged against the conveyance roller211by an elastic member such as a spring (not shown) with a force of 1.2N. The rotatable member212is rotated in association with the rotation of the conveyance roller211.

The sheet P is conveyed by the conveyance roller211to a first image reading process portion231comprising the first image reading apparatus202and a first backing roller203. The sheet P is further conveyed by the conveyance roller211to a second image reading process portion232comprising the second image reading apparatus204and a second backing roller205. The first image reading apparatus202and the first backing roller203have the same structures as the second image reading apparatus204and the second backing roller205, respectively. The first image reading apparatus202is arranged below the conveyance path for the sheet P. The second image reading apparatus204is arranged above the conveyance path for the sheet P. The first image reading apparatus202and the second image reading apparatus204are arranged opposite to each other with respect to the conveyance path. The first image reading apparatus202and the second image reading apparatus204have different reading directions. Therefore, the first image reading apparatus202and the second image reading apparatus204can read image information of images formed on both sides (front side and back side) of the sheet P only by passing the sheet P through the conveyance path one time without reversing the sheet P in another conveyance path.

The sheet P passed through the second image reading apparatus204is guided by an outlet lower guide224and an outlet upper guide225, and is discharged from the inspection apparatus102by a second conveyance roller pair206and conveyed to the sorter103. The material of the outlet lower guide224and the outlet upper guide225is SUS 420 CP. The polishing process is applied to the contact surfaces of the outlet lower guide224and the outlet upper guide225with the sheet P to improve the surface properties of the contact surfaces so as not to damage the sheet P. Since the second conveyance roller pair206has the same structure as the first conveyance roller pair201, a description thereof will be omitted. An outlet sensor226detects the sheet P discharged from the inspection apparatus102. Since the outlet sensor226has the same structure as the inlet sensor223, a description thereof will be omitted.

A conveyance speed of the sheet P conveyed by the first pair of conveyance rollers (conveyance portion)201is the same as a conveyance speed of the sheet P discharged from the printer101. A line connecting a nip of the first conveyance roller pair201and a nip of the second conveyance roller pair206is arranged so as to substantially coincide with a sheet-passing surface through the first image reading apparatus202and a sheet-passing surface through the second image reading apparatus204. The reason is to keep the sheet P conveyed in the inspection apparatus102straight so as not to apply deflecting stress to the sheet P.

In a case in which the conveyance path of the sheet P is bent, the deformation stress to the sheet P increases at the bent point, so that an issue occurs in that the image formed on the sheet P is damaged or the paper dust is generated. In a case in which the image of the sheet P is damaged or the paper dust is generated, noise is mixed in the read image information of the sheet P so that good read image information cannot be obtained. Therefore, the conveyance path of the sheet P is configured so as not to cause the above-mentioned issue.

FIG. 3is an explanatory view of the first image reading process portion231. The first image reading process portion231comprises the first image reading apparatus202and the first backing roller203provided in the inspection apparatus102. The printer101is disposed on the right side ofFIG. 3. The sorter103is disposed on the left side ofFIG. 3. The floor is belowFIG. 3and the ceiling is aboveFIG. 3.FIG. 4is a cross-sectional view of the first image reading process portion231taken along line IV-IV ofFIG. 3.

The first image reading apparatus202includes a contact image sensor (hereinafter referred to as CIS)301serving as an image reading portion. A reading glass (transparent member)302is disposed at a predetermined distance L from an upper surface T of the CIS301. In the present embodiment, the predetermined distance L is 13.1 mm, but the present disclosure is not limited thereto. In the present embodiment, the thickness of the reading glass302is 3.9 mm, but the present disclosure is not limited thereto. The reading glass302has a length of 38 mm in the conveyance direction CD of the sheet P and a length of 366 mm in a main scanning direction MS orthogonal to the conveyance direction CD. The first image reading apparatus202is arranged opposite to the reading glass302on a side (second side) opposite to a side (first side) on which the sheet P is conveyed with respect to the reading glass302, and reads an image of the sheet P conveyed on the reading glass302.

A surface treatment is applied to the sheet-passing surface (passing surface)302aof the reading glass302on which the sheet P passes in order to eliminate elements that obstruct the conveyance property of the sheet P such as sticking of the sheet P to the sheet-passing surface302a. As described above, the sheet-passing surface302aof the reading glass302has the same level as the line connecting the nip of the first conveyance roller pair201and the nip of the second conveyance roller pair206.

A dustproof plate303configured to prevent intrusion of foreign substance is arranged between the CIS301and the reading glass302. The dustproof plate303includes a steel plate303aof ZINKOTE (trademark) having a thickness of 1 mm, and foamed urethane sponges (elastic members)303band303cfixed to the steel plate303aby double-sided adhesive tape. The sponge303bis disposed between the steel plate303aand a non-sheet-passing surface302bof the reading glass302. The sponge303cis disposed between the steel plate303aand an upper surface T of the CIS301. The dustproof plate303including sponges303aand303bextends in the main scanning direction along the reading glass302.

In order to smoothly deliver the sheet P conveyed from the first conveyance roller pair201to the sheet-passing surface302aof the reading glass302, an introduction guide305is provided on the upstream side of the reading glass302in the conveyance direction CD. The introduction guide305is made of a spring material (elastic material) made of SUS 304 CSP-1/2H having a thickness of 0.1 mm. One end of the introduction guide305is fixed to a frame306by screws307, and the other end (free end) of the introduction guide305is disposed so as to be in close contact with the upper surface of the reading glass302. A portion of the frame306is a supporting member of the introduction guide305and also serves as a sheet guide configured to guide the sheet P.

CIS holders401and402made of aluminum as holding members configured to hold the CIS301are fixed to both ends of the CIS301with respect to the main scanning direction MS by screws. The CIS holders401and402also hold the reading glass302at a predetermined distance (predetermined value) L from the upper surface T of the CIS301. Positioning portions (butting portions)401aand402ahaving protrusions projecting toward the reading glass302are provided on the upper portions of the CIS holders401and402, respectively. The sheet-passing surface302aof the reading glass302is butted against the positioning portions401aand402a. As shown inFIG. 4, the non-sheet-passing surface302bof the reading glass302is butted against a pressing member403. The pressing member403includes a steel plate403aof ZINKOTE (trademark) and a hard rubber (elastic member)403b. The hard rubber403bis disposed between the steel plate403aand the non-sheet-passing surface302bof the reading glass302. The pressing member403presses the reading glass302against the positioning portions401aand402ato fix the reading glass302.

The first backing roller203is hereinafter simply referred to as a backing roller203. The backing roller203is disposed so that an outer periphery of the backing roller203is separated by a predetermined distance from the sheet-passing surface302aof the reading glass302, thereby forming a gap δ between the outer periphery of the backing roller203and the sheet-passing surface302aof the reading glass302(FIG. 8). In the embodiment, the predetermined distance is 0.4 mm. However, the predetermined distance is not limited to 0.4 mm, and is appropriately set in accordance with the specifications of the inspection apparatus102. The backing roller203is disposed opposite to the reading glass302on the side (the first side) on which the sheet P is conveyed with respect to the reading glass302. The backing roller203functions as a regulating portion (an opposed member) configured to regulate the conveyance of the sheet P so as to properly maintain the distance between the reading glass302and the sheet P within a predetermined range. The backing roller203has an aluminum pipe material203aand shafts203bpressed into both ends of the pipe material203a. A black urethane coat is applied to an outer peripheral surface of the pipe material203a. The backing roller203has an outer diameter of 20 mm.

At each of both ends of the backing roller203with respect to the main scanning direction MS, a butt roller404having an outer diameter of 20.8 mm are arranged coaxially with the backing roller203. The backing roller203is supported by an arm405and is urged by springs406at a pressure of 5.9N. As a result, as shown inFIG. 4, the butt rollers404are butted against the sheet-passing surface302aof the reading glass302, so that the gap δ (FIG. 8) between the reading glass302and the backing roller203is held at 0.4 mm.

A rotational force is transmitted from a drive motor (not shown) to the end of the backing roller203on the right side (rear side) ofFIG. 4through a timing belt (not shown). The backing roller203rotates at the same conveyance speed as the first conveyance roller pair201and the second conveyance roller pair206. This is to prevent the backing roller203from becoming a conveyance resistance of the sheet P when the sheet P passes through the gap δ (FIG. 8) between the reading glass302and the backing roller203. Thus, paper dust generated when the sheet P passes through the backing roller203can be reduced.

FIG. 5is an explanatory view of a focal position Q of the CIS301. The focal position Q of the CIS301is 0.2 mm±0.2 mm from the reading glass302. By setting the gap δ (FIG. 8) between the reading glass302and the outer periphery of the backing roller203to 0.4 mm, no matter where the sheet P passes through the gap δ (FIG. 8), the sheet P passes through a focal region of the CIS301, thereby ensuring good image reading. A light emitting portion351of the CIS301irradiates light M toward the focal position Q. A light receiving portion352of the CIS301receives light J.

A predetermined distance L between the upper surface T of the CIS301and the reading glass302shown inFIG. 3is held by the CIS holders401and402shown inFIG. 4. The dustproof plate303is disposed between the CIS301and the reading glass302. The sponge303bis squeezed between the steel plate303aand the reading glass302. An original thickness of the sponge303bbefore mounting is 3 mm. A thickness D of the sponge303bsqueezed after mounting is 2 mm. The sponge303cis squeezed between the steel plate303aand the CIS301. An original width of the sponge303cbefore mounting is 7 mm. A width E of the sponge303csqueezed after mounting is 5.8 mm. Squeezing amounts of the sponges303band303care set to 1 mm and 1.2 mm, respectively.

In this way, the sponges303band303care arranged in a state in which the sponges303band303care squeezed between the reading glass302and the CIS301, thereby blocking the path through which foreign substances such as dirt and paper dust enter between the reading glass302and the CIS301. However, the squeezed sponge303bpresses the reading glass302toward the backing roller203on the side (first side) on which the sheet P is conveyed.FIG. 6is an explanatory view of the gap δ between the reading glass302and the backing roller203. Due to a reaction force W generated when the sponge303bis squeezed, the reading glass302deflects toward the backing roller203as indicated by the two-dot chain line inFIG. 6. If the reading glass302deflects toward the backing roller203, the gap δ between the reading glass302and the backing roller203becomes smaller than the set value. In a case in which the gap δ becomes smaller than the set value, resistance may be generated in the conveyance of the sheet P in the gap δ between the reading glass302and the backing roller203, or paper dust may be generated. Therefore, in the embodiment, the deflection of the reading glass302is suppressed by the introduction guide305. Hereinafter, a mechanism configured to suppress the deflection of the reading glass302toward the backing roller203caused by the reaction force W generated when the sponge303bis squeezed will be described.

In order to smoothly deliver the sheet P conveyed by the first conveyance roller pair201onto the reading glass302, the introduction guide305is disposed upstream of the reading glass302in the conveyance direction CD. The introduction guide305is arranged on the side of the reading glass302with respect to a conveyance path in which the sheet P is conveyed. The introduction guide305can prevent the sheet P from being scratched by being caught on the end of the reading glass302, the sheet P from being broken, or the sheet P from being jammed.

As described above, a line connecting the nip of the first conveyance roller pair201and the nip of the second conveyance roller pair206is arranged so as to substantially coincide with the sheet-passing surface302aof the reading glass302, thereby the sheet P is conveyed linearly during image reading. This is to reduce damage to an image of the sheet P and generation of paper dust by preventing deflecting stress from being applied to the sheet P during image reading. Therefore, a material requiring a thickness as a material for forming the introduction guide305is unsuitable. This is because a large deflecting stress is applied to the sheet P by a step (level difference) formed between the sheet-passing surface302aof the reading glass302and the introduction guide305, and image damage and paper dust are generated.

Hereinafter, a mechanism will be described in which a step formed by the sheet-passing surface302aof the reading glass302and an introduction guide1305causes paper dust and image damage in a case in which the introduction guide1305having a large thickness is used in place of the introduction guide305according to the present embodiment.FIG. 7is an explanatory view of the deflecting of the sheet P in a case in which the introduction guide1305of the reference example is used. The gap δ between the sheet-passing surface302aof the reading glass302and the outer periphery of the backing roller203is set to 0.4 mm as described above. The introduction guide1305of the reference example is made of a steel plate having a thickness of 1 mm. The sheet P conveyed in the conveyance direction CD passes through the gap δ of 0.4 mm from a position having a height of 1 mm starting from the sheet-passing surface302aof the reading glass302. At this time, as shown inFIG. 7, the sheet P is slightly bent. Therefore, the sheet P and the introduction guide1305of the reference example are more rubbed, and paper dust is generated.

Next, a case in which the introduction guide305according to the present embodiment is used will be described with reference toFIG. 8.FIG. 8is an explanatory view of the bending of the sheet P in a case in which the introduction guide305of the embodiment is used. The introduction guide305is made of a spring material having a thickness of 0.1 mm. The introduction guide305is provided with a bent portion305d. The radius of curvature of the bent portion305dis preferably 0.5 mm or more. The sheet P conveyed in the conveyance direction CD passes through the gap δ having a height of 0.1 mm from a position having a height of 0.4 mm starting from the sheet-passing surface302aof the reading glass302. Since the height of the step formed by the sheet-passing surface302aof the reading glass302and the introduction guide305is 0.1 mm, the bending of the sheet P is suppressed. Thus, sliding resistance when the sheet P passes on the introduction guide305is reduced, and generation of paper dust is suppressed.

It is desirable that the height of the introduction guide305from the reading glass302is smaller than the gap δ between the reading glass302and the backing roller203and as low as possible. The introduction guide305of the embodiment is made of the spring material of SUS 304 CSP-1/2H having a thickness of 0.1 mm. By using the material having the thickness of 0.1 mm, the step caused by the reading glass302and the introduction guide305is reduced, and the generation of image damage and paper dust caused when the sheet P passes on the introduction guide305is reduced. The introduction guide305of the embodiment is preferably made of a thin spring material having the thickness of 0.1 mm. The spring material includes, for example, spring steel such as high carbon steel, alloy steel, and stainless steel.

As described above, the dustproof plate303configured to prevent foreign substance such as paper dust and dirt from entering is disposed between the CIS301and the reading glass302in the state in which the sponge303bis squeezed. If the introduction guide305of the present embodiment is not provided on the reading glass302, as shown inFIG. 6, the reading glass302deflects toward the backing roller203and deforms so that the gap δ between the reading glass302and the backing roller203becomes small. However, in the embodiment, the introduction guide305made of the spring material is disposed on the reading glass302.

FIG. 9is a view of the introduction guide305fixed to the frame306. The introduction guide305extends in the main scanning direction MS. An end portion (hereinafter referred to as one end portion)305aon an upstream side of the introduction guide305with respect to the conveyance direction (sub-scanning direction) CD of the sheet P is fixed to the frame306as a fixed end portion by a plurality of screws307. The frame306is fixed to a casing102aof the inspection apparatus102via another frame411(FIG. 4). Since the one end portion305aas the fixed end of the introduction guide305is fixed to the frame306by the screws307, the introduction guide305is surely grounded, and generation of static electricity can be prevented.

An end portion (hereinafter referred to as the other end portion)305bon the downstream side of the introduction guide305with respect to the conveyance direction CD of the sheet P is a free end portion. When the frame306is attached to the another frame411by screws410(FIG. 4), the other end portion305b, which is the free end portion of the introduction guide305, is disposed so as to be in close contact with the upper surface of the reading glass302. At this time, the other end portion305b, which is the free end portion of the introduction guide305, is attached so as to be in close contact with the reading glass302while being deformed by about 2.6 mm in the height direction. The other end portion305b, which is the free end portion of the introduction guide305formed of the spring material (leaf spring), generates a spring force toward the reading glass302. The other end portion305b, which is the free end portion of the introduction guide305, presses the reading glass302toward the side (second side) on which the first image reading apparatus202is disposed. The spring force of the introduction guide305can cancel the force of deflecting the reading glass302toward the backing roller203by the reaction force W generated when the sponge303bis squeezed. That is, the other end portion305bof the introduction guide305presses the reading glass302with a pressing force that suppresses deformation of the reading glass302by the sponge303band flattens the reading glass302. Therefore, the sheet-passing surface302aof the reading glass302is held in a substantially horizontal state by the introduction guide305. The sheet P is conveyed without giving bending stress to the sheet P by the introduction guide305.

FIG. 10is a perspective view of the first image reading apparatus202.FIG. 11is a perspective view of the first image reading apparatus202in which the frame306, the introduction guide305and the backing roller203are assembled. The other end portion305b, which is the free end portion of the introduction guide305, is in close contact with the reading glass302to prevent the deflection of the reading glass. Further, since the step between the reading glass302and the introduction guide305is small, image damage and paper dust are suppressed when the sheet P passes on the reading glass302, and image data with less noise can be read.

The first image reading apparatus202has been described above. The second image reading apparatus204is arranged in the direction opposite to that of the first image reading apparatus202with respect to the conveyance path of the sheet P. Since the configuration, functions and effects of the second image reading apparatus204are the same as those of the first image reading apparatus202, a description of the second image reading apparatus204is omitted.

According to the embodiment, the deflection of the reading glass302can be reduced to improve the image reading performance.

This application claims the benefit of Japanese Patent Application No. 2021-007005, filed Jan. 20, 2021, which is hereby incorporated by reference herein in its entirety.