JP5056030B2 - Image reader - Google Patents

Description

  The present invention relates to an image reading apparatus, and more particularly to a sheet-through type image reading apparatus used as an image input apparatus in a copying machine, a scanner, or the like.

  Conventionally, as an image reading apparatus that optically reads an image of a document, a platen set system that reads an image of the document placed on the platen glass, and a sheet that conveys the document one by one and reads the image of the document in the middle of conveyance The through method was used alone or in combination. The sheet-through method has advantages in downsizing, low cost, low noise, high speed image reading, and high print productivity, and both monochrome copying machines and color copying machines have become mainstream image reading apparatuses.

  In the case of the sheet-through method, the image reading position is fixed on a transparent member (elongated reading glass), and the reading optical system is focused on the image surface of the document conveyed through the reading glass. A portion that is easily affected by foreign matter such as dust adhered to the glass and is shielded by the foreign matter becomes streak-like image noise in the read image.

  The foreign material adhering to the transparent member is mainly an adhesive foreign material such as adhesive sticking or adhesive peel off from the tape affixed to the original, correction liquid, ball pen ink lump, eraser scrap, etc., and the original slides on the reading glass. Easy to be transferred to the part. Further, such a sticky foreign matter does not easily peel off and has a problem of causing image noise. In addition, there is a problem that floating foreign matters such as paper dust and dust in the air scattered from the conveyed document stay on the reading glass and cause image noise. In the sheet-through method, since the document is conveyed while being held in contact with a guide plate by a roller or the like, stress is applied to the document mainly composed of paper, and paper powder falls from the document surface.

  Therefore, in Patent Document 1, a step is provided on the upstream side of the reading position of the reading glass, and a rising member for raising the document is provided on the downstream side of the reading position of the reading glass, and corresponds to the reading position of the reading glass. A document feeding device is disclosed in which a portion is in sliding contact with the leading edge of a document. In the document feeder, foreign matter on the reading glass is removed by bringing the leading end of the document into sliding contact with the portion corresponding to the reading position of the reading glass.

However, the document feeder has a problem that foreign matter on the reading glass cannot be sufficiently removed. More specifically, since the leading edge of the original does not easily turn around at the boundary between the step and the reading glass, foreign matter tends to accumulate at the boundary. In particular, when the original is curled upward, the leading edge of the original does not easily turn around at the boundary between the step and the reading glass, and it is difficult to remove foreign matter.
JP 2002-314753 A

  Accordingly, an object of the present invention is a sheet-through system, which can more reliably eliminate foreign matter adhering to or remaining on a reading glass for reading an image of a conveyed document, and causing a streak noise in a read image. It is an object of the present invention to provide an image reading apparatus that can prevent the above-described problem.

The present invention includes a document conveying unit that sends a document so as to pass through a reading position, a reading unit that optically reads an image of a document that is conveyed at the reading position, a document that is conveyed at the reading position, and the reading unit. And a step portion provided on the upstream side in the document transport direction from the reading position and so as to form a surface higher than the main surface of the transparent member. When the leading edge and / or the trailing edge of the document passes through the reading position, the stepped portion is relatively relative to the transparent member than when the central portion of the document passes through the reading position. as the retracted position is moved to the upstream side in the transport direction, a moving means for moving the step portion from the initial position, has a, is moved with the stepped portion in the retracted position, the leading end of the document or after The end is the When the step portion is moved to the initial position without directly contacting the difference portion and the step portion is moved to the initial position, the document is lifted to the step portion, and the portions other than the leading and trailing edges of the document There characterized Rukoto is conveyed in a state of non-contact with the transparent member.

  According to the present invention, when the leading end and the trailing end of the document pass over the transparent member, the step portion and the step portion are arranged such that the step portion moves relative to the transparent member to the upstream side in the transport direction. The positional relationship with the transparent member is changed. For this reason, the leading edge and / or trailing edge of the document is not lifted by the stepped portion, and can easily come into contact with the transparent member. A relatively large amount of foreign matter adheres to the portions other than the leading and trailing edges of the document, whereas a very small amount of foreign matter adheres to the leading and trailing ends of the document. The transparent member can be cleaned by bringing it into contact with the transparent member.

  Furthermore, when the leading edge and the trailing edge of the document pass over the transparent member, the step portion moves relative to the transparent member to the upstream side in the conveyance direction, so that the boundary portion between the step portion and the transparent member This makes it easier for the leading edge and trailing edge of the document to come into contact with each other. Since foreign matter tends to accumulate at the boundary between the stepped portion and the transparent member, the transparent member can be made cleaner by scraping the foreign matter accumulated in the portion with the leading edge and the trailing edge of the document.

  In the present invention, the moving means may include stepped portion moving means for reciprocating the stepped portion along the transport direction. Furthermore, in the first aspect of the present invention, the apparatus further comprises document detection means provided upstream of the stepped portion in the transport direction for detecting the presence or absence of the document, wherein the stepped portion moving means includes the document detection means. The step portion may be moved upstream in the transport direction in response to detecting the leading edge of the document.

  In the present invention, the position of the step when the leading edge of the document passes through the reading position is a retreat position, and the conveyance path length of the document from the detection position of the document detection means to the reading position is Z. The distance from the retracted position to the reading position is L, the document transport speed is S, and it takes for the stepped portion to move to the retracted position after the document detection means detects the leading edge of the document. When time is T, the relationship of T ≦ (Z−L) / S may be established. By establishing this relationship, when the leading edge of the document reaches the reading position, the movement of the step portion to the retracted position is completed. As a result, the leading edge of the document can easily come into contact with the transparent member.

  In the present invention, there may be further provided a document detecting means provided upstream of the stepped portion in the transport direction and detecting the presence or absence of the document, wherein the stepped portion moving means is configured such that the document detecting means is located behind the document. The step portion may be moved to the upstream side in the transport direction in response to detection of the end.

  In the present invention, the position of the step when the rear end of the document passes through the reading position is defined as a retreat position, and the conveyance path length of the document from the detection position of the document detection means to the reading position is defined as Z. The distance from the retracted position to the reading position is L, the document transport speed is S, and the step detection unit detects the trailing edge of the document until the stepped portion moves to the retracted position. When the time taken for T is T ′, the relationship of T ′ ≦ (Z−L) / S may be established. When this relationship is established, when the trailing edge of the document reaches the reading position, the movement of the step portion to the retracted position is completed. As a result, the trailing edge of the document can easily come into contact with the transparent member.

  In the present invention, the moving means may include transparent member moving means for reciprocating the transparent member along the transport direction.

  In the present invention, there is further provided an original detection unit that is provided upstream of the step portion in the transport direction and detects the presence / absence of the original, and the transparent member moving unit includes: In response to detecting the end, the transparent member may be moved downstream in the transport direction. Since the foreign matter accumulated at the boundary between the stepped portion and the transparent member moves to the downstream side together with the transparent member, the foreign matter is scraped off by the trailing edge of the document.

  Embodiments of an image reading apparatus according to the present invention will be described below with reference to the accompanying drawings.

(Overall configuration of image reader)
FIG. 1 is a configuration diagram of an image reading apparatus 1 according to an embodiment of the present invention. The image reading apparatus 1 includes a document conveying unit 2 as a document conveying unit that sends out a document P so as to pass through a reading position A, and a reading unit that optically reads an image of the document P conveyed at the reading position A. The image reading unit 3. The image reading apparatus 1 includes a platen set method for reading an image of the document P placed on the hand-held glass 39 and a sheet-through method for reading an image of the document P conveyed by the document conveying unit 2. Various image reading methods can be implemented. In the present embodiment, since the image reading is performed by the sheet through method, the description of the platen set method is omitted. In the following, for simplicity of explanation, “the conveyance direction of the document P” is simply referred to as “conveyance direction”, “upstream side of the conveyance direction of the document P” is simply referred to as “upstream side”, and “ The “downstream side in the transport direction” is simply referred to as “downstream side”.

  The document conveying unit 2 includes a paper feed tray 20, a pickup roller 21, a separating roller 22, a paper feed roller 23, a registration roller pair 24, a pre-reading roller pair 25, a pre-reading sensor 26, a post-reading roller pair 27, and a paper discharge roller pair. 28 and a paper discharge tray 29. On the other hand, the image reading unit 3 includes an exposure lamp 30, a first mirror 31, a second mirror 32, a third mirror 33, an imaging lens 34, a CCD 35, a reading glass 36, a step sheet 37, a scooping guide 38, and a hand-held glass 39. Is provided.

  First, the configuration of the document conveying unit 2 will be described. A plurality of documents P are placed on the sheet feed tray 20. The pickup roller 21 picks up a part of a plurality of documents P. The separating roller 22 and the sheet feeding roller 23 separate and convey one by one when a plurality of documents P are picked up by the pickup roller 21. The registration roller pair 24 corrects the inclination of the original P that has been conveyed one by one and conveys it to the pre-reading roller pair 25. The pre-reading roller pair 25 conveys the original P onto the reading glass 36. The pre-read sensor 26 detects the presence or absence of the document P that has passed through the pre-read roller pair 25. After reading, the roller pair 27 conveys the original P that has passed over the reading glass 36 to the paper discharge roller pair 28. The paper discharge roller pair 28 discharges the original P conveyed from the roller pair 27 after reading to the paper discharge tray 29.

  Next, the configuration of the image reading unit 3 will be described. The exposure lamp 30, the first mirror 31, the second mirror 32, the third mirror 33, the imaging lens 34, and the CCD 35 serve as reading means for optically reading the image of the document P conveyed at the reading position A. . Specifically, the exposure lamp 30 serves to irradiate the reading position A with light, and is realized by, for example, a fluorescent lamp. The first mirror 31, the second mirror 32, and the third mirror 33 serve to guide the light reflected by the original P sent to the reading position A to the imaging lens 34. Specifically, the first mirror 31 reflects the light reflected by the document surface sent to the reading position A in the left direction in FIG. The second mirror 32 reflects the light reflected by the first mirror 31 downward in FIG. The third mirror 33 reflects the light reflected by the second mirror 32 in the right direction in FIG.

  The imaging lens 34 plays a role of imaging the light reflected by the first mirror 31, the second mirror 32 and the third mirror 33 on the CCD 35. The CCD 35 plays a role of converting a document image formed on the imaging lens 34 into digital image data. The reading glass 36 is a transparent member disposed between the document P conveyed at the reading position A and the first mirror 31, and transmits light from the exposure lamp 30 to the document P side. The light reflected by is transmitted to the first mirror 31.

  Here, the configuration in the vicinity of the reading position A will be described in more detail with reference to FIG. FIG. 2 is a diagram illustrating a configuration of the image reading apparatus 1 in the vicinity of the reading position A.

  Around the reading glass 36, a reading guide 51 and a scooping guide 38 for scooping up the document P that has passed the reading position A are arranged. Further, in order to prevent the document P being conveyed from directly touching the reading glass 36, the stepped sheet 37 has a stepped portion C on the surface of the reading glass 36 on the document P side upstream of the reading position A. It is provided to be formed. Accordingly, the stepped portion C, which is the edge portion of the stepped sheet 37, is provided on the upstream side of the reading position A, and forms a surface higher than the surface of the reading glass 36 on the original P side (the upper surface of the stepped sheet 37). To come. The step sheet 37 has a thickness (step) of 0.65 mm and is formed of a material having a low sliding resistance (preferably a friction coefficient of 0.3 or less) such as ultrahigh molecular weight polyethylene, and is in contact with the surface of the reading glass 36. It is arranged in the state.

  In this image reading apparatus 1, the document P conveyed rightward while sliding on the upper surface of the step sheet 37 by the pre-reading roller pair 25 and the post-reading roller pair 27 has a reading position A at a predetermined height depending on the thickness of the step sheet 37. Therefore, the image is conveyed in a non-contact state with the reading glass 36, and the original image is read through the reading glass 36 by reading means. Since there is a gap between the original surface and the reading glass 36, it is possible to prevent adhesive foreign matters such as correction liquid from adhering to the reading glass 36.

  By the way, in the image reading apparatus 1, since the original P is conveyed in a non-contact state with respect to the reading glass 36, adhesive foreign matter from the original P is not transferred to the reading glass 36. On the other hand, floating foreign matters such as paper dust fall on the surface of the reading glass 36 from the original P.

  Therefore, in the image reading apparatus 1, when the leading edge and / or the trailing edge of the document P passes the reading position A, the stepped portion C has the reading glass more than when the central portion of the document P passes the reading position A. Moving means is provided for changing the positional relationship between the stepped portion C and the reading glass 36 so that the position moves relative to the upstream side. Thus, by changing the positional relationship between the stepped portion C and the reading glass 36 according to the position of the original P, the leading edge or the rear end of the original P can easily come into contact with the reading glass 36, and paper dust or the like Floating foreign matter will be removed.

(About transportation means)
Below, the structure of a moving means is demonstrated, referring drawings. The moving means includes a stepped portion moving means for moving the stepped portion C (stepped sheet 37) in the transport direction and a transparent member moving means for moving the reading glass 36 in the transport direction. Further, the moving means includes angle changing means for changing the angle formed by the step sheet 37 and the reading glass 36.

  First, the step part moving means will be described with reference to FIGS. FIG. 3 is an exploded perspective view of the step portion moving means and the angle changing means. FIG. 4 is a diagram showing the behavior of the step portion moving means and the angle changing means. The step part moving means includes a step sheet attaching plate 52, a rack attaching plate 53, a motor 54, gears 55, 56, 57, 57 ′, racks 58, 58 ′, a light shielding part 59, and a light shielding part detection sensor 60.

  The step sheet mounting plate 52 is made of, for example, metal. A step sheet 37 is attached to the downstream end of the step sheet attaching plate 52 so as to protrude to the downstream side. Further, hinges are provided at both ends to which the step sheet 37 is attached, and a rack mounting plate 53 is attached via the hinges. As a result, the level difference sheet mounting plate 52 is swingably supported with respect to the rack mounting plate 53. As the step sheet mounting plate 52 swings, the step sheet 37 also swings. Further, the rack attachment plate 53 is attached to the racks 58 and 58 ′ by screws.

  The motor 54 is, for example, a stepping motor. A gear 55 is attached to the motor 54. The gears 56 and 57 play a role of transmitting the driving force of the motor 54. The gear 57 ′ is connected to the gear 57 via a shaft. Further, the racks 58, 58 ′ and the gears 57, 57 ′ are engaged with each other. Thereby, when the motor 54 rotates, the racks 58 and 58 'move in the transport direction, and the rack mounting plate 53, the step sheet mounting plate 52, and the step sheet 37 move in the transport direction. Specifically, when the motor 54 rotates counterclockwise in the state shown in FIG. 4A, the gear 57 ′ rotates counterclockwise, and as shown in FIG. 4B, the rack 58 ′, The rack mounting plate 53, the step sheet mounting plate 52, and the step sheet 37 move to the upstream side. Hereinafter, the position of the stepped portion C when the stepped portion C is at a position relatively close to the reading position A as shown in FIG. Further, as shown in FIG. 4B, the position of the stepped portion C when the stepped portion C is on the upstream side from the initial position D is referred to as a retracted position E.

  Further, as shown in FIG. 3, a light shielding portion 59 is provided so as to extend from the downstream end portion of the rack 58 ′ to the downstream side. In the vicinity of the light shielding part 59, a light shielding part detection sensor 60 for detecting the presence or absence of the light shielding part 59 is provided. The light shielding part detection sensor 60 detects whether the stepped part C is at the initial position D or the retracted position E by detecting the presence or absence of the light shielding part 59. Therefore, when the stepped portion C is at the initial position D, the light-blocking portion detection sensor 60 shields the light-receiving portion by the light-blocking portion 59 and also when the stepped portion C is at the retracted position E. The light receiving unit 59 is arranged so as not to be shielded from light. The light-shielding part detection sensor 60 outputs a detection signal when the light-receiving part is shielded from light.

  Next, the angle changing means will be described with reference to FIGS. The angle changing means includes a motor 61, gears 62 and 63, cams 64 and 64 ′, a light shielding part 65, and a light shielding part detection sensor 66.

  The motor 61 is, for example, a stepping motor. A gear 62 is attached to the motor 61. The gear 63 meshes with the gear 62 and plays a role of transmitting the driving force of the motor 61. The cam 64 is connected to the gear 63. Furthermore, the cam 64 ′ is connected to the cam 64 via a shaft. That is, when the gear 63 rotates, the cams 64 and 64 ′ also rotate. 4A, when the motor 61 rotates counterclockwise in a state where the small diameter portion of the cam 64 ′ is in contact with the step sheet mounting plate 52, the cam 64 ′ rotates clockwise. Then, as shown in FIG. 4C, the large diameter portion of the cam 64 ′ pushes up the step sheet mounting plate 52. As a result, the step sheet 37 changes from a horizontal state to an inclined state while its downstream end is in contact with the reading glass 36. In the following, the angle formed between the reading glass 36 and the step sheet 37 in the state of FIG. 4A is an initial angle θ ′ (0 ° in the present embodiment), and in the state of FIG. And the step sheet 37 is referred to as an inclination angle θ. Note that a relationship of θ ′ <θ is established between the initial angle θ ′ and the inclination angle θ.

  Further, as shown in FIG. 3, an arc-shaped light shielding portion 65 is provided so as to protrude from the side surface of the cam 64 ′. In the vicinity of the light shielding part 65, a light shielding part detection sensor 66 for detecting the presence or absence of the light shielding part 65 is provided. The light shielding part detection sensor 66 detects whether the reading glass 36 and the step sheet 37 have an initial angle θ ′ or an inclination angle θ by detecting the presence or absence of the light shielding part 65. Therefore, when the reading glass 36 and the step sheet 37 are at the initial angle θ ′, the light-shielding part detection sensor 66 shields the light-receiving part from the light-shielding part 65 and the reading glass 36 and the step sheet 37. Are arranged such that the light receiving part 65 is not shielded from light by the light shielding part 65. The light shielding part detection sensor 66 outputs a detection signal when the light receiving part is shielded from light.

  Next, the transparent member moving means will be described with reference to FIGS. FIG. 5 is an exploded perspective view of the transparent member moving means. FIG. 6 shows the operation of the transparent member moving means. The transparent member moving means includes a reading glass mounting plate 71, holders 72 and 72 ′, a motor 73, gears 74, 75, 76, and 76 ′, racks 77 and 77 ′, a light shielding portion 78, and a light shielding portion detection sensor 79.

  The reading glass mounting plate 71 is made of, for example, metal, and the reading glass 36 is placed on the main surface thereof. Both ends of the reading glass 36 placed on the reading glass mounting plate 71 are fixed to the reading glass mounting plate 71 by holders 72 and 72 ', respectively. Further, the scooping guide 38 is attached to the reading glass mounting plate 71 so as to be positioned downstream of the reading glass 36. Further, the reading glass mounting plate 71 is attached to the racks 77 and 77 ′ by screws.

  The motor 73 is, for example, a stepping motor. A gear 74 is attached to the motor 73. The gears 75 and 76 play a role of transmitting the driving force of the motor 73. The gear 76 'is connected to the gear 76 via a shaft. Furthermore, the racks 77 and 77 ′ and the gears 76 and 76 ′ are engaged with each other. Thus, when the motor 73 rotates, the racks 77 and 77 ′ move in the transport direction, and the reading glass mounting plate 71 and the reading glass 36 move in the transport direction. Specifically, in the state shown in FIG. 6A, when the motor 73 rotates clockwise, the gear 76 ′ rotates clockwise, and as shown in FIG. 6B, the rack 77 ′ and the reading glass are rotated. The mounting plate 71 and the reading glass 36 move downstream. In the following, the position of the downstream end of the reading glass 36 when the downstream end of the reading glass 36 is relatively upstream as shown in FIG. Call it. As shown in FIG. 6B, the position of the downstream end of the reading glass 36 when the downstream end of the reading glass 36 is relatively downstream is referred to as a downstream position G.

  Further, as shown in FIG. 5, a light shielding portion 78 is provided so as to extend from the downstream end portion of the rack 77 ′ to the downstream side. In the vicinity of the light shielding part 78, a light shielding part detection sensor 79 for detecting the presence or absence of the light shielding part 78 is provided. The light shielding part detection sensor 79 detects whether the downstream end of the reading glass 36 is at the initial position F or the downstream position G by detecting the presence or absence of the light shielding part 78. Therefore, when the downstream end of the reading glass 36 is at the initial position F, the light shielding portion detection sensor 79 does not shield the light receiving portion by the light shielding portion 78 and the downstream end of the reading glass 36 When in the downstream position G, the light-shielding part 78 is arranged so that the light-receiving part is shielded from light. The light shielding part detection sensor 79 outputs a detection signal when the light receiving part is shielded from light.

(About operation of image reader)
The operation of the image reading apparatus 1 configured as described above will be described with reference to the drawings. FIG. 7 is a block diagram of the image reading apparatus 1. FIG. 8 is a flowchart illustrating an operation performed by the control unit 100. FIG. 9 is a diagram illustrating the operation of the image reading apparatus 1.

  As shown in FIG. 7, the control unit 100 of the image reading apparatus 1 includes a paper feeding unit 101 including a pickup roller 21, a separating roller 22, and a paper feeding roller 23, a registration roller pair 24, a pre-reading roller pair 25, and a reading. A conveyance unit 102 including a rear roller pair 27 and a paper discharge roller pair 28, a pre-reading sensor 26, a CCD 35, motors 54, 61, 73, and light shielding unit detection sensors 60, 66, 79 are connected. The control unit 100 is realized by a CPU, for example, and controls the entire image reading apparatus 1. Hereinafter, the operation of the image reading apparatus 1 will be described with reference to FIG.

  First, the control unit 100 receives an instruction to start reading the document P from the user and drives the sheet feeding unit 101 (step S1). Specifically, the control unit 100 feeds the original P placed on the paper feed tray 20 to the pickup roller 21, the separation roller 22, and the paper feed roller 23 one by one.

  When feeding of the document P is started, the control unit 100 drives the transport unit 102 (step S2). Specifically, the control unit 100 starts the rotation of the registration roller pair 24, the pre-reading roller pair 25, the post-reading roller pair 27, and the paper discharge roller pair 28, and conveys the document P. At this time, the stepped portion C is located at the initial position D as shown in FIG. Therefore, the light receiving unit of the light shielding unit detection sensor 60 is in a state where the light shielding unit 59 is shielded from light, and a detection signal is output from the light shielding unit detection sensor 60 to the control unit 100.

  When the conveyance of the document P is started, the control unit 100 stands by while determining whether or not the pre-reading sensor 26 has detected the leading edge of the document P (step S3). If the pre-read sensor 26 does not detect the leading edge of the document P, this process repeats step S3. If the pre-read sensor 26 detects the leading edge of the document P, the process proceeds to step S4.

  When the leading edge of the document P is detected, the control unit 100 drives the motor 54 to move the stepped portion C to the upstream retracted position E (step S4). Specifically, the control unit 100 drives the motor 54 until the light shielding unit 59 of the light receiving unit of the light shielding unit detection sensor 60 is unshielded and no detection signal is output from the light shielding unit detection sensor 60. As a result, the stepped portion C moves from the initial position D to the retracted position E as shown in FIG. When the stepped portion C moves to the retracted position E, the leading edge of the document P comes into direct contact with the main surface of the reading glass 36 without contacting the stepped portion C. Since there is almost no foreign matter such as adhesive tape on the front end of the original P, the front end of the original P scrapes off the foreign matter as it passes over the reading glass 36.

  Next, the control unit 100 stands by while determining whether or not a predetermined time has elapsed since the leading edge of the document P was detected (step S5). This predetermined time is preferably set to a time from when the leading edge of the document P is detected until the leading edge of the document P reaches the reading position A. If the predetermined time has not elapsed, step S5 is repeated. If the predetermined time has elapsed, the process proceeds to step S6.

  When the predetermined time has elapsed, the control unit 100 drives the motor 54 to move the stepped portion C to the initial position D on the downstream side (step S6). Specifically, the control unit 100 drives the motor 54 until the light receiving unit of the light shielding unit detection sensor 60 is shielded by the light shielding unit 59 and a detection signal is output from the light shielding unit detection sensor 60. . Thereby, as shown in FIG. 9C, the stepped portion C moves from the retracted position E to the initial position D. After the leading edge of the document P passes through the reading position A, the step C is moved to the initial position D, whereby the document P is lifted to the step C, and a portion other than the leading and trailing edges of the document P (for example, , The central portion of the original P) is prevented from contacting the reading glass 36.

  Next, the control unit 100 waits while determining whether or not the pre-reading sensor 26 has detected the trailing edge of the document P (step S7). If the pre-read sensor 26 does not detect the trailing edge of the document P, this process repeats step S7. If the pre-read sensor 26 detects the trailing edge of the document P, the process proceeds to step S8.

  When the trailing edge of the document P is detected, the control unit 100 drives the motor 54 to move the stepped portion C to the upstream retracted position E (step S8). Specifically, the control unit 100 drives the motor 54 until the light shielding unit 59 of the light receiving unit of the light shielding unit detection sensor 60 is unshielded and no detection signal is output from the light shielding unit detection sensor 60. As a result, the stepped portion C moves from the initial position D to the retracted position E as shown in FIG. When the stepped portion C moves to the retracted position E, the trailing edge of the document P comes into direct contact with the main surface of the reading glass 36 without contacting the stepped portion C. Since there is almost no foreign matter such as adhesive tape on the rear end of the original P, the rear end of the original P scrapes off the foreign matter on the reading glass 36.

  Finally, the control unit 100 stands by while repeatedly determining whether or not the conveyance of the document P has been completed (step S9). When the conveyance of the original P is completed, this process ends.

  As described above, according to the image reading apparatus 1 according to the present embodiment, when the leading edge and the trailing edge of the document P pass over the reading glass 36, the leading edge and the trailing edge of the document P are in contact with the reading glass 36. The stepped portion C is retracted so that the document P is easily moved, and when a portion other than the leading edge and the trailing edge of the document P passes over the reading glass 36, a portion other than the leading edge and the trailing edge of the document P is read glass 36. The stepped portion C is brought close to the reading position A so that it is difficult to come into contact with the reading position A. A relatively large amount of foreign matter adheres to portions other than the leading edge and the trailing edge of the document P, whereas foreign matter hardly adheres to the leading edge and the trailing edge of the document P. Therefore, by moving the stepped portion C as described above, foreign matter can be prevented from adhering to the reading glass 36, and the reading glass 36 can be cleaned by the leading edge or the trailing edge of the document P.

  Further, when the leading edge and the trailing edge of the document P pass over the reading glass 36, the stepped portion C moves to the retracted position E, so that the document P is placed at the boundary portion between the stepped portion C and the reading glass 36. The front end and the rear end are easy to contact. Since foreign matter tends to accumulate at the boundary portion between the stepped portion C and the reading glass 36, the reading glass 36 can be made clean by scraping the portion with the leading edge and the trailing edge of the original P.

  By the way, in the image reading apparatus 1 according to the present embodiment, as shown in FIG. 9B, the transport path length of the document P from the position where the sensor 26 before reading is detected to the reading position A of the sensor 26 before reading is Z. The distance from the retreat position E to the read position A is L, the transport speed of the original P is S, and it takes from the time when the sensor 26 before reading detects the leading edge of the original P to the step C moved to the retract position E. When the time is T, it is preferable that the relationship of T ≦ (Z−L) / S is satisfied. When this relationship is established, when the leading edge of the document P reaches the reading position A, the movement of the stepped portion C to the retracted position E is completed. As a result, the leading edge of the document P can easily come into contact with the reading glass 36.

  Furthermore, in the image reading apparatus 1 according to the present embodiment, when the time required for the stepped portion C to move to the retracted position E after the pre-reading sensor 26 detects the trailing edge of the document P is T ′, It is preferable that the relationship of T ′ ≦ (Z−L) / S is satisfied. When this relationship is established, when the trailing edge of the document P reaches the reading position A, the movement of the stepped portion C to the retracted position E is completed. As a result, the rear end of the document P is likely to come into contact with the reading glass 36.

  The step C is positioned at the initial position D only after the leading edge of the document P passes the reading position of the pre-reading sensor 26 and until the trailing edge of the document P passes the reading position. May be.

(Other control examples)
In the image reading apparatus 1 according to the embodiment, the stepped portion C is moved. However, instead of moving the stepped portion C, the reading glass 36 may be moved. FIG. 10 is a configuration diagram in the vicinity of the reading position A in another control example.

  As shown in FIG. 10A, when a portion other than the rear end of the document P passes through the reading position A, the downstream end of the reading glass 36 is positioned at the initial position F. When the pre-read sensor 26 detects the trailing edge of the document P, as shown in FIG. 10B, the control unit 100 drives the motor 73 to move the reading glass 36 to the downstream side. The end of the reading glass 36 is positioned at the downstream position G. As a result, the foreign matter accumulated at the boundary between the stepped portion C and the reading glass 36 moves to the downstream side together with the reading glass 36 and is scraped off by the trailing edge of the original P.

  Note that the image reading apparatus 1 can perform the operation shown in FIG. 9 and the operation shown in FIG. 10 in combination.

1 is a configuration diagram of an image reading apparatus according to an embodiment of the present invention. It is the figure which showed the structure of the image reading apparatus in the reading position vicinity. It is a disassembled perspective view of a step part moving means and an angle changing means. It is the figure which showed the mode of operation | movement of a level | step difference part moving means and an angle change means. It is a disassembled perspective view of a transparent member moving means. It is the figure which showed operation | movement of the transparent member moving means. It is a block diagram of an image reading apparatus. It is the flowchart which showed the operation | movement which a control part performs. It is a figure showing operation of an image reading device. It is the figure which showed operation | movement of the image reading apparatus in the other example of control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Document conveying part 3 Image reading part 25 Pre-reading roller pair 26 Pre-reading sensor 36 Reading glass 37 Level difference sheet 38 Scooping guide 51 Reading guide 52 Level difference sheet attaching plate 53 Rack attaching plates 54, 61, 73 Motor 55, 56, 57, 57 ', 62, 63, 74, 75, 76, 76' Gear 58, 58 ', 77, 77' Rack 59, 65, 78 Light-shielding part 60, 66, 79 Light-shielding part detection sensor 64, 64 ' Cam 71 Reading glass mounting plate 100 Control unit 101 Paper feeding unit 102 Conveying unit A Reading position C Stepped portion D, F Initial position E Retraction position G Downstream position P Document

Claims (8)

A document conveying means for feeding the document so as to pass through the reading position;
Reading means for optically reading an image of a document conveyed at the reading position;
A transparent member disposed between the document conveyed at the reading position and the reading unit;
A step portion provided upstream of the reading position in the document transport direction and provided to form a surface higher than the main surface of the transparent member;
When the leading edge and / or trailing edge of the document passes through the reading position, the stepped portion is relatively in the transport direction with respect to the transparent member than when the central portion of the document passes through the reading position. Moving means for moving the stepped portion from the initial position so as to be the retracted position moved to the upstream side of
Equipped with a,
When the stepped portion is moved to the retracted position, the leading edge or the rear end of the document does not contact the stepped portion but directly contacts the main surface of the transparent member, and the stepped portion is moved to the initial position. document is lifted step portion, the tip and a portion other than the rear end of the document is conveyed in a state of non-contact with the transparent member image reading apparatus according to claim Rukoto. The moving means is
Including step part moving means for reciprocating the step part along the transport direction;
The image reading apparatus according to claim 1. An original detection unit that is provided upstream of the stepped portion in the transport direction and detects the presence or absence of the original;
Further comprising
The step portion moving means moves the step portion to the upstream side in the transport direction in response to the document detecting means detecting the leading edge of the document;
The image reading apparatus according to claim 2. The position of the step when the leading edge of the document passes through the reading position is defined as a retracted position, the transport path length of the document from the detection position of the document detecting means to the reading position is defined as Z, and from the retracted position The distance to the reading position is L, the transport speed of the document is S, and the time it takes for the stepped portion to move to the retracted position after the document detection means detects the leading edge of the document is T. When
T ≦ (Z−L) / S
That the relationship of
The image reading apparatus according to claim 3. An original detection unit that is provided upstream of the stepped portion in the transport direction and detects the presence or absence of the original;
Further comprising
The step portion moving means moves the step portion to the upstream side in the transport direction in response to the document detection means detecting the trailing edge of the document;
The image reading apparatus according to claim 2, wherein the image reading apparatus is an image reading apparatus. The position of the step when the rear end of the document passes through the reading position is defined as a retracted position, the transport path length of the document from the detection position of the document detecting means to the reading position is defined as Z, and the retracted position The distance from the reading position to the reading position is L, the conveyance speed of the document is S, and the time it takes for the stepped portion to move to the retracted position after the document detection means detects the trailing edge of the document. When T '
T ′ ≦ (Z−L) / S
That the relationship of
The image reading apparatus according to claim 5. The moving means is
Including transparent member moving means for reciprocating the transparent member along the transport direction;
The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus. An original detection unit that is provided upstream of the stepped portion in the transport direction and detects the presence or absence of the original;
Further comprising
The transparent member moving means moves the transparent member to the downstream side in the transport direction in response to the document detecting means detecting the trailing edge of the document;
The image reading apparatus according to claim 7.

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