JP4479674B2 - Image reader - Google Patents

Description

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

  Conventionally, as an image reading apparatus for optically reading an image of a document, a platen set method for reading an image of a document placed on a platen glass, and a document are conveyed one by one, and an image of the document is read during conveyance. The sheet-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 has become the mainstream of image reading devices in monochrome copiers. The introduction is also desired.

  In the case of the sheet-through method, the image reading position is fixed on a transparent member (long 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 the adhesive part of the tape affixed to the original or peeling of the glue, correction liquid, ball pen ink lump, eraser scrap, etc., and the original rubs 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, Patent Documents 1 and 2 disclose measures for conveying a document in a non-contact state with respect to the reading glass by providing a step on the upstream side of the reading glass in the document conveying direction. In this non-contact conveyance method, the adhesive foreign matter can be prevented from adhering to the reading glass. On the other hand, floating foreign substances are those that are caught in a document to be conveyed and discharged naturally when the document comes into contact with the reading glass. There is a case where the rear end of the document loses its support immediately after passing through the step and comes into contact with the reading glass, and the rear end of the document entrains floating foreign matter and discharges it from the reading glass.

  However, the range in which the trailing edge of the document comes into contact with the reading glass is small, and it is difficult to reliably remove floating foreign matters remaining on the reading glass. In particular, the trailing edge of the document is curled or easily wrinkled, and is often not uniform. Therefore, contact with the reading glass is uncertain, and floating foreign matter that cannot be removed can be removed from the reading glass. Will stay on top.

  Patent Document 3 discloses, as an improvement measure of Patent Document 1, a capture member that captures foreign matter between a step and a reading position. However, maintenance (replacement and cleaning) of the capture member is necessary and complicated. In addition, a capture member cannot be installed at the reading position, and paper dust that has fallen to the reading position cannot be captured.

On the other hand, a monochrome image reader emphasizes character reproducibility by increasing the reproducibility of high-density parts such as characters and reducing the reproducibility of low-density parts such as the document background. Since image processing that is clearly reproduced is performed, image noise due to minute floating foreign matters such as paper dust does not become so obvious. However, in color image reading devices, since it is necessary to reproduce gradations such as photographs, it is important to read subtle gradation changes in a document. Fine streak noise is generated in the read image.
JP-A-9-307695 JP 11-146140 A Japanese Patent Laid-Open No. 2001-223832

  Accordingly, an object of the present invention is a sheet-through method, which prevents the sticky foreign matter from being transferred to a transparent member for reading an image of a conveyed document, and reliably prevents floating foreign matter. An object of the present invention is to provide an image reading apparatus which can be eliminated and can prevent the occurrence of streak noise in a read image.

In order to achieve the above object, an image reading apparatus according to the present invention comprises:
A document conveying means for feeding the documents one by one and passing them 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 transparent member that is disposed on the transparent member and upstream of the reading position in the document conveying direction , and the document is conveyed while being in contact with the upper surface thereof, so that the conveyed document is in a posture parallel to the transparent member. A manuscript guide member having a predetermined upper surface and a predetermined thickness;
Moving means for reciprocally moving either the transparent member or the document guide member in a state in which the document guide member is in contact with the transparent member, substantially parallel to the document conveyance direction;
The moving means, at the start of movement, immediately moves the transparent member backward after moving the transparent member upstream in the document transport direction, or immediately moves the document guide member backward after moving the document guide member downstream in the document transport direction,
The distance between the reading position and original conveying direction downstream side tip of the document guide member and x1, when the relative moving distance between the transparent member and the document guide member is a x2, Ri near relationship x1 <x2 ,
The document guide member removes foreign matter on the transparent member by the downstream end in the document transport direction ;
It is characterized by.

  According to the image reading apparatus of the present invention, the document is conveyed by the document guide member while being floated from the transparent member, and it is possible to prevent the sticky foreign matter from being transferred from the document surface to the transparent member. Then, by reciprocating either the transparent member or the document guide member so as to satisfy the above x1 <x2 substantially parallel to the document conveyance direction, the floating foreign matters remaining on the transparent member are surely removed from the reading position. it can. Accordingly, streak noise does not occur in the read image.

  In the image reading apparatus according to the present invention, it is preferable that the transparent member and the document guide member change their relative positions while being in contact with each other at least at a position where x1 = x2. Further, when the distance from the downstream end of the document guide member of the transparent member in the document transport direction to the downstream end surface in the document transport direction is x3, the relationship may be x2 ≧ x3. It becomes possible to discharge the foreign matter reliably from the transparent member.

  The document guide member may always be in contact with the transparent member, or may be held in a non-contact state with respect to the transparent member when the document is transported and contacted with the transparent member when foreign matter is excluded. Also good.

  Further, a sheet member that is in contact with the back surface of the transparent member and is provided integrally with the document guide member may be provided. The back surface of the transparent member can also be cleaned. Alternatively, the shape of the edge portion on the downstream side in the document conveyance direction of the document guide member may gradually change in a plan view. That is, the edge portion of the document guide member may have a shape inclined at a small angle with respect to the document conveyance direction or an arc shape other than the shape orthogonal to the document conveyance direction.

  Embodiments of an image reading apparatus according to the present invention will be described below with reference to the accompanying drawings. In each embodiment, the same parts and the same parts are denoted by the same reference numerals, and redundant description is omitted.

(Image reader, see FIGS. 1-6)
FIG. 1 shows an image reading apparatus 1 according to an embodiment of the present invention. The image reading apparatus 1 includes a platen set method for reading an image of a document (not shown) placed on the platen glass 10 and a sheet-through method for reading the document D conveyed by the automatic document conveying device 20. In addition, a reading optical system (scanner) 50 is installed.

  Reading by the platen set method is performed, for example, by irradiating a document placed on the platen glass 10 with a lamp 53 such as a rare gas fluorescent lamp, and forming an image of reflected light from the document surface via mirrors 54, 55, and 56. This is performed by entering the lens 57 and forming an image on the imaging unit (CCD color line sensor) 58. The lamp 53 and the mirror 54 are mounted on the first slider 51, and the mirrors 55 and 56 are mounted on the second slider 52, and are movable in the sub-scanning direction Y, respectively. A white reference plate 11 for performing shading correction is installed on the upstream side of the platen glass 10 in the sub-scanning direction Y.

  On the other hand, the automatic document feeder 20 includes a plurality of roller pairs 21, 22, 23, and 24. The documents D are picked up one by one from the tray 25, fed from the roller pairs 21, 22, 23 onto the reading glass 12, and read by the reading optical system 50 set immediately below the reading position A. 24 is discharged onto the tray 26.

  The image data read by the reading optical system 50 is transferred to an image processing unit 63 (see FIG. 10), and further transferred to a laser scanning unit (not shown) of a digital copying apparatus, and a sheet is formed by a known electrophotographic method. An image is formed on top. The document image reading process by the platen set method or the sheet through method and the image forming process by the electrophotographic method are well known, and detailed description thereof is omitted.

  FIG. 2 shows an enlarged cross-section of a document reading unit using the sheet-through method. Around the reading glass 12, document guide plates 25a, 25b, 26a, and 26b and a guide 27 for scooping up the document that has passed the reading position A are arranged. A document guide sheet 30 is attached to the mounting plate 35 on the reading glass 12 upstream of the reading position A in the document conveying direction B so that the document being conveyed does not directly touch the reading glass 12. It is placed in contact with the surface of the reading glass 12.

  In the image reading apparatus 1, an original conveyed rightward while sliding on the upper surface of the original guide sheet 30 by the conveyance roller pairs 23 and 24 has a predetermined position at a reading position A depending on the thickness of the guide sheet 30. The image is conveyed to the reading glass 12 in a non-contact state, and the original image is read by the reading optical system through the reading glass 12. Since there is a gap between the original surface and the reading glass 12, adhesive foreign matters such as correction liquid do not adhere to the reading glass 12.

  Further, the reading glass 12 is held by a holding member 13, and as shown in FIG. 3, the crank arm 15 connected to the shaft 14 of the holding member 13 is rotated once by the eccentric cam 16 by a drive motor (stepping motor) 17. By doing so, it reciprocates in parallel with the document conveying direction B. The amount of movement of the reading glass 12 can also be controlled by the number of drive pulses of the drive motor 17. The movement timing of the reading glass 12 will be described in detail later.

  Specifically, the document guide sheet 30 is formed of a material having a thickness (step) of 0.65 mm and a low sliding resistance (preferably a friction coefficient μ0.3 or less) such as ultrahigh molecular weight polyethylene. If a material having low sliding resistance is used, the load when the reading glass 12 is moved is reduced, and troubles such as generation of abnormal noise can be prevented.

  The document guide plate 25b regulates the posture of the document D being conveyed, and the clearance from the reading glass 12 is set to 1.2 mm in order to perform stable image reading. If the gap with the reading glass 12 is increased to 1.4 mm or more, the posture of the conveyed document is not stabilized, the paper passing property is deteriorated, and the density of the read image varies.

  By the way, in the image reading apparatus 1, since the original is conveyed in a non-contact state with respect to the reading glass 12, adhesive foreign matter from the original is not transferred to the reading glass 12. On the other hand, floating foreign matters such as paper dust fall on the surface of the reading glass 12 from the original, and many of them are caught in the original being conveyed and discharged from the reading glass 12. However, some of the floating foreign matters such as paper dust and dust in the air are located on the reading glass 12 from the vicinity of the leading end step of the document guide sheet 30 as indicated by symbol E in FIG. A will remain over A.

  Therefore, in the image reading apparatus 1, the reading glass 12 is reciprocated from the home position (position shown in FIG. 4A) by the drive motor 17 and the eccentric cam 16, thereby causing floating foreign matter at the front end of the document guide sheet 30. E is removed from the reading position A to prevent the occurrence of streak noise in the read image. That is, when the distance between the tip of the guide sheet 30 and the reading position A is x1, and the moving distance of the reading glass 12 by the eccentric cam 16 is x2, the relation of x1 <x2 is set. The guide sheet 30 is elongated in the direction orthogonal to the document conveying direction B, and the leading edge portion thereof is in uniform contact with the reading glass 12, so that the floating foreign matter E can be reliably removed from the reading position A. Specifically, x1 is 6 mm and x2 is 10 mm.

  First, as shown in FIG. 4A, the reading glass 12 is moved by x2 (10 mm) from the home position in the direction opposite to the document conveying direction B with the floating foreign matter E remaining on the reading glass 12. (See FIG. 4B). As a result, the floating foreign matter E is scraped to a portion shifted from the reading position A on the reading glass 12. Thereafter, when the reading glass 12 is returned to the home position, the reading position A is cleanly cleaned (see FIG. 4C). The floating foreign matter E has almost no adhesion to the reading glass 12 and can be easily removed at the leading edge portion of the guide sheet 30. Further, since the guide sheet 30 is formed of a member having low sliding resistance, the surface of the reading glass 12 is not damaged.

  Further, as shown in FIG. 5, when the distance from the leading edge portion of the document guide sheet 30 of the reading glass 12 to the downstream end surface in the document conveying direction B is x3, the distance x3 and the moving distance x2 of the reading glass 12 The relationship may be x2 ≧ x3. Thus, by moving the reading glass 12 back and forth by the distance x2, the floating foreign matter E on the reading glass 12 is pushed out from the end face of the reading glass 12 and completely removed from the reading glass 12.

  In the above description, the reading glass 12 is moved. However, the reading glass 12 may be fixed and the document guide sheet 30 may be reciprocated. Moreover, these moving means can also be comprised combining arbitrary mechanisms.

  With respect to the shape of the document guide sheet 30, various shapes can be adopted for the tip (downstream side in the document transport direction B) edge portion in plan view. Normally, as shown in FIG. 6A, the edge portion 30a is a straight line orthogonal to the document transport direction B, but may be gradually changed. That is, it is skewed as shown in FIG. 6 (B), is skewed with respect to the center as shown in FIG. 6 (C), and is arcuate as shown in FIG. 6 (D). Also good.

  When the leading edge portion 30a of the document guide sheet 30 has various shapes, the distance x1 from the reading position A is set with reference to the most upstream side in the document conveyance direction B of each edge portion 30a.

(See other document guide sheets, Fig. 7)
As shown in FIG. 7, the document guide sheet 30 may be installed so as to be swingable in the vertical direction with a support shaft 31 provided at the rear end of the guide sheet 30 as a fulcrum. The document guide sheet 30 contacts / separates on the reading glass 12 as it swings. In this case, the document guide sheet 30 is attached to the frame of the automatic document feeder 20 via the support shaft 31.

  The document guide sheet 30 guides the conveyance of the document in a state where the leading edge portion is separated from the reading glass 12 (see FIG. 7A). When the floating foreign substance E is removed, the guide sheet 30 swings downward and comes into contact with the reading glass 12, and in this contact state, the reading glass 12 moves from the home position by a distance x2 (see FIG. 7B). ). Thereafter, the reading glass 12 returns to the home position, and the guide sheet 30 swings upward (see FIG. 7C). Thereby, the floating foreign matter E is removed from the reading position A.

(Cleaning the back side of the reading glass, see Fig. 8)
As shown in FIG. 8, a cleaning sheet 32 may also be provided on the back side of the reading glass 12. The cleaning sheet 32 is made of a material having a low sliding resistance similar to the document guide sheet 30 and is fixed to the mounting plate 36. As the reading glass 12 reciprocates by the distance x2 as described above, the foreign matter adhered to the back surface of the reading glass 12 is cleaned. In addition, the structure which cleans only the back surface of the reading glass 12 in this way may be sufficient.

(Reading glass cleaning control)
Next, control for reciprocating the reading glass 12 in order to remove floating foreign substances from the reading position A will be described. Even when the document guide sheet 30 is reciprocated instead of the reading glass 12, the control is performed at the same timing.

  First, the appearance of the image reading apparatus 1 is shown in FIG. The image reading apparatus 1 is installed on the upper side of the digital copying apparatus 5, and the automatic document feeder 20 is in a closed state (see FIG. 9A) covering the platen glass 10 and the reading glass 12 with the back as a fulcrum 40 (see FIG. 9A) and an open state (see FIG. 9B), a sensor 41 that is manually movable and detects an open / close state is provided. An operation / display panel 45 as job input means is installed on the front side. The panel 45 is provided with a reading start (print start) button, a numeric keypad for setting the number of prints, and the like, and various job mode setting screens are displayed. The job mode includes single-sided original reading, double-sided original reading, single-sided copying, combination of double-sided copying, copy magnification, various finishing processes such as sorting and stapling.

  FIG. 10 shows a schematic configuration of the control unit. The control unit includes a ROM 61 storing a program and a RAM 62 temporarily storing parameters centered on the CPU 60, and an image read by the image forming process control unit 64, the image reading process control unit 65, and the imaging unit (CCD) 58. The processing unit 63 is connected. Further, detection signals from the open / close detection sensor 41 of the automatic document feeder 20, the home position detection sensor 42 of the reading glass 12, and the document detection sensor 43 on the tray 25 are input to the CPU 60.

(See Control Example 1, FIG. 11)
First, when it is detected that a document is placed on the tray 25 (YES in step S1), it is determined whether or not the automatic document feeder 20 is in a closed state (step S2). If it is open, a warning that the automatic document feeder 20 should be closed is displayed on the panel 45 (step S3). If it is in the closed state, it is determined whether or not the reading glass 12 is set at the home position (step S4). If it is not set at the home position, the drive motor 17 is turned on, and the reading glass 12 is returned to the home position (step S5). If it is set at the home position, a READY signal indicating that the preparation for reading the original is completed is output (step S6).

  Thereafter, the job content is input (step S7), and when the print start button is turned on (YES in step S8), the drive motor 17 is turned on (step S9). Thus, when the reading glass 12 reciprocates and returns to the home position (step S10), the drive motor 17 is turned off (step S11). As a result, the reading glass 12 reciprocates once, and floating foreign matters on the reading glass 12 are removed from the reading position A. Thereafter, the conveyance of the original, the reading of the image, and the printing operation are executed according to the job content (step S12).

  In this control example 1, the reading glass 12 is moved for cleaning only when the automatic document feeder 20 is in the closed state. Accordingly, the reading glass 12 is prevented from being damaged. Further, since the cleaning is performed immediately before the job operation, the document image is read with the reading glass 12 always being cleaned cleanly.

(Refer to Control Example 2 and FIG. 12)
In this control example 2, the reading glass 12 is cleaned after the job operation is completed. That is, when the preliminary operation of the image reading apparatus 1 and the copying apparatus 5 is completed (YES in step S21), the job content is input (step S22), and the print start button is turned on (YES in step S23), the job operation is performed. Is executed (step S24). Thereafter, when the job operation is completed (YES in step S25), the reading glass 12 is cleaned (see step S26, steps S9, S10, and S11 in FIG. 11), and a READY signal is output (step S27). Note that the job operation executed in step S24 varies depending on the contents of the input job.

(Refer to Control Example 3 and FIG. 13)
In this control example 3, the reading glass 12 is cleaned when the automatic document feeder 20 changes from the open state to the closed state. That is, after the READY signal is output in step S31, it is detected that the automatic document feeder 20 is opened (YES in step S32), and further, it is detected that the automatic document feeder 20 is closed (in step S33). YES), the reading glass 12 is cleaned (see step S34, steps S9, S10, and S11 in FIG. 11).

  When the automatic document feeder 20 is opened, dust in the atmosphere may adhere to the reading glass 12, or dust may adhere due to the touch of the user's hand. According to the control example 3, such dirt can be removed.

(Refer to Control Example 4 and FIG. 14)
In this control example 4, the reading glass 12 is cleaned when the power is turned on. That is, when the power is turned on (step S41), it is confirmed that the automatic document feeder 20 is closed (YES in step S42), and the reading glass 12 is cleaned (step S43, FIG. 11). The READY signal is output (see steps S9, S10, and S11) (step S44). When the power is off, it cannot be detected whether the automatic document feeder 20 is in a closed state or an open state. Therefore, when the power is turned on, the reading glass 12 is cleaned after confirming that the automatic document feeder 20 is in the closed state.

(Refer to Control Example 5 and FIG. 15)
In this control example 5, when a paper jam occurs in the automatic document feeder 20, the reading glass 12 is cleaned when the paper jam is removed. That is, if a paper jam is detected during the job operation (step S51) (YES in step S52) and the paper jam removal process is completed (YES in step S53), for example, the frame of the automatic document feeder 20 is opened to open the original. When it is detected that the frame has been taken out and closed, the reading glass 12 is cleaned (see step S54, steps S9, S10 and S11 in FIG. 11).

  When a paper jam occurs, the document is excessively stressed by the collision with the conveyance guide plate, and paper dust and minute foreign matters are often peeled off from the document. In addition, there is a case where a user contacts the reading glass 12 and a foreign matter adheres for paper jam processing. Therefore, it is effective to clean the reading glass 12 when the paper jam is removed.

(See Control Example 6, FIG. 16)
In this control example 6, the reading glass 12 is cleaned when the reading optical system 50 performs the shading correction operation. When reading a document image, the reading optical system 50 turns on the lamp 53 to read the amount of light reflected from the document by the imaging unit (CCD) 58 and processes the density as image information. When reading a plurality of documents, the lamp 53 is continuously turned on for a long time. At this time, the amount of light of the lamp 53 is the largest at the time of lighting, attenuates according to the lighting time, and becomes stable after a certain time. As it is, the amount of light incident on the imaging unit (CCD) 58 is reduced as compared with the initial lighting state, and the image is processed as a dark image (high density image). In order to prevent this, the white reference plate 11 is read again and the shading correction operation is performed before the amount of change in the amount of light of the lamp 53 exceeds a predetermined reference value.

  This shading correction operation is performed by moving the reading optical system 50 directly below the white reference plate 11, and the conveyance and reading of the document are temporarily stopped. Therefore, in this control example 6, when the shading correction operation is performed even during the job operation, the reading glass 12 is cleaned. The foreign matter accumulated on the reading glass 12 can be removed by continuous conveyance of the original.

  That is, when the print start button is turned on (YES in step S61), a shading correction operation is first executed by the reading optical system 50 (step S62). Thereafter, the reading optical system 50 is moved to the document reading position A (step S63), the lamp 53 is turned on and a timer is started (step S64).

  Next, an original conveying operation is executed to start reading an original image (step S65). When the original passes the reading position A (step S66), it is determined whether or not the next original is to be conveyed (step S67). . If there is no next original, the transport operation is stopped (step S68), the lamp 53 is turned off (step S69), and the READY signal is output (step S70).

  On the other hand, if the next original is to be conveyed, it is determined whether or not it is time to redo the shading correction accompanying the light amount attenuation of the lamp 53 based on the count value T of the timer (step S71). When it is time to redo the shading correction, the reading optical system 50 is moved directly below the white reference plate 11 to execute a shading correction operation (step S72), and then the reading optical system 50 is moved to the reading position A ( Step S73). In parallel with this, the reading glass 12 is cleaned (see step S74, steps S9, S10, and S11 in FIG. 11).

(Refer to Control Example 7, FIGS. 17 and 18)
In this control example 7, the reading glass 12 is cleaned while the trailing edge of the previous document and the leading edge of the next document that are successively conveyed pass the reading position A. In this case, the cleaning operation may be started before the trailing edge of the preceding document passes the reading position A, or when the distance between the trailing edge of the preceding document and the reading position A is outside the image reading range. May be started.

  As shown in FIG. 17, the automatic document feeder 20 is provided with a document detection sensor 44 on the upstream side of the reading position A. A predetermined time after the trailing edge of the previous document D1 is detected by this sensor 44, that is, The forward movement (cleaning operation) of the reading glass 12 is started at the timing when the rear end of the previous document D1 passes the reading position A, and the reading glass 12 is moved until the leading edge of the next document D2 reaches the reading position A. Complete the backward movement (cleaning operation).

  Incidentally, wrinkles or the like may occur near the edge of the document and be distorted, so that the reading density and the linearity of the image cannot be ensured accurately. Even if an image near the edge of the original is read, it is difficult for the copying apparatus 5 to form a good image near the edge of the paper. Therefore, normally, an image is not read in the vicinity of the edge of the document (an area of about 5 mm). Prohibiting the movement of the reading glass 12 during image reading is necessary to avoid disturbance of the reading image. However, when the outside of the image reading range of 5 mm passes the reading position A, the reading glass 12 is moved. Even if it is made to do, there is no trouble in reading the image. Therefore, the document interval at which the reading glass 12 is moved for cleaning in the control example 7 means an interval including the trailing end non-reading area (about 5 mm) of the previous document.

  Specifically, as shown in FIG. 18, when the print start button is turned on (YES in step S81), a shading correction operation is first executed by the reading optical system 50 (step S82). Thereafter, the reading optical system 50 is moved to the document reading position A (step S83), and the lamp 53 is turned on (step S84).

  Next, a document conveying operation is executed and reading of a document image is started (step S85). When the trailing edge of the document is detected by the detection sensor 44 (YES in step S86), a timer is started (step S87), and when the trailing edge of the document reaches the reading position A based on the count value of this timer. If the non-reading area is taken into consideration, the reading glass 12 is cleaned when the position 5 mm before the trailing edge of the document reaches the reading position A (YES in step S88) (step S89, step of FIG. 11). (See S9, S10, S11).

  If the original passes through the reading position A in parallel with the cleaning operation (YES in step S88), it is determined whether or not the next original is to be conveyed (step S90). If there is no next original, the transport operation is stopped (step S91), the lamp 53 is turned off (step S92), and the READY signal is output (step S93). If there is a next original, the process returns to step S85.

(Other image reading device, see FIG. 19)
As shown in FIG. 19, the image reading apparatus 1 has an automatic document feeder 20 fixed to the main body frame of the reading apparatus 1 with screws 9, and the automatic document feeder 20 shifts to an open state in which the reading glass 12 is exposed. There is something that prohibited. This is to prohibit easy opening operation. In some cases, the automatic document feeder 20 is integrally formed with the main body frame of the reading apparatus 1 and is essentially prohibited from shifting to the open state.

  In such a forbidden open type image reading apparatus 1, the open / close detection sensor 41 shown in FIG. 9 is unnecessary, and it is possible to determine whether or not the reading glass 12 can be cleaned by determining its detection state. It is unnecessary.

(Other examples)
The image reading apparatus according to the present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the gist thereof. In particular, the configuration of the mechanism for conveying the document and the reading optical system is arbitrary.

It is a schematic block diagram which shows one Example of the image reader which concerns on this invention. It is a principal part expanded sectional view of the image reading apparatus shown in FIG. It is a schematic sectional drawing which shows the moving mechanism of reading glass. It is explanatory drawing which shows the cleaning operation | movement by a document guide sheet. It is explanatory drawing which shows the other example of the moving distance of reading glass. It is a top view which shows the various shapes of the front-end | tip edge part of a document guide sheet. It is explanatory drawing which shows the cleaning operation | movement by the original document guide sheet | seat of another structure. It is sectional drawing of the example which enabled cleaning of the back surface of reading glass. It is a perspective view which shows the external appearance of an image reader, (A) shows a closed state, (B) shows an open state. 2 is a block diagram illustrating a control unit of a copying machine including an image reading device. FIG. It is a flowchart figure which shows the cleaning control example 1 of a reading glass. It is a flowchart figure which shows the cleaning control example 2 of a reading glass. It is a flowchart figure which shows the cleaning control example 3 of a reading glass. It is a flowchart figure which shows the cleaning control example 4 of a reading glass. It is a flowchart figure which shows the cleaning control example 5 of a reading glass. It is a flowchart figure which shows the cleaning control example 6 of a reading glass. FIG. 6 is an explanatory diagram illustrating a state where a document is continuously conveyed. It is a flowchart figure which shows the cleaning control example 7 of a reading glass. It is a perspective view which shows the external appearance of the image reading apparatus which consists of another structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image reading device 12 ... Reading glass 17 ... Drive motor 20 ... Automatic document feeder 30 ... Document guide sheet (cleaning member)
32 ... Back surface cleaning sheet 50 ... Reading optical system A ... Reading position

Claims (9)

A document conveying means for feeding the documents one by one and passing them 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 transparent member that is disposed on the transparent member and upstream of the reading position in the document conveying direction , and the document is conveyed while being in contact with the upper surface thereof, so that the conveyed document is in a posture parallel to the transparent member. A document guide member having an upper surface parallel to the predetermined thickness and a predetermined thickness;
Moving means for reciprocally moving either the transparent member or the document guide member in a state in which the document guide member is in contact with the transparent member, substantially parallel to the document conveyance direction;
The moving means, at the start of movement, immediately moves the transparent member backward after moving the transparent member upstream in the document transport direction, or immediately moves the document guide member backward after moving the document guide member downstream in the document transport direction,
The distance between the reading position and original conveying direction downstream side tip of the document guide member and x1, when the relative moving distance between the transparent member and the document guide member is a x2, Ri near relationship x1 <x2 ,
The document guide member removes foreign matter on the transparent member by the downstream end in the document transport direction ;
An image reading apparatus.   2. The image reading apparatus according to claim 1, wherein the transparent member and the document guide member change relative positions in a state where they are in contact with each other at least at a position where x1 = x2.   3. The relationship of x2 ≧ x3 is established, where x3 is a distance from the downstream end of the document guide member on the transparent member to the downstream end surface in the document transport direction. The image reading apparatus described in 1.   3. The relationship of x2> x3 is satisfied, where x3 is a distance from the downstream end of the original guide member of the transparent member in the original conveyance direction to the downstream end surface in the original conveyance direction. The image reading apparatus described in 1.   5. The region in which the document to be conveyed does not contact the transparent member is formed between the downstream end of the document guide member on the downstream side in the document conveyance direction and the transparent member. The image reading apparatus described in 1.   6. The image reading apparatus according to claim 1, further comprising second moving means for contacting / separating the document guide member on the transparent member. A regulating member that regulates the posture of the upper surface of the conveyed document;
The document to be conveyed is conveyed while being regulated in a posture parallel to the transparent member by the document guide member and the regulating member;
The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus. Further, the contact with the back surface of the transparent member, the image reading apparatus according to any one of claims 7 to claims 1, characterized in that with the original guide member integrally with provided sheet member. The document guide member is the shape of the original conveying direction downstream side edge portion in plan view are inclined with respect to a direction perpendicular to the document conveying direction, or, according to claim claims 1, characterized in that an arc-shaped 9. The image reading device according to any one of 8 above.

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