JP5115438B2 - 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 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 and color copiers. .

  In the case of the sheet-through method, the image reading position is fixed, that 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. Due to the configuration, it is easily affected by foreign matter such as dust attached to the reading glass and residual dust, and a portion shielded by the foreign matter becomes streak-like image noise in the read image. If the manuscript is paper, it is inevitable that fine foreign substances such as fillers and fibers contained in the paper such as calcium carbonate adhere to the reading glass.

  In order to solve such problems, conventionally, in the process of processing a read image, dust on the image is detected and a warning is given to the user, streak noise is eliminated as image processing, or the reading glass is moved. Measures were taken to prevent them from reading garbage continuously. However, these measures cannot eliminate the accumulation of dust on the reading glass, and eventually a service person needs to clean the reading glass surface.

  Further, as disclosed in Patent Document 1, an image reading apparatus has been proposed in which an elastic member is rotated to clean the reading glass. As described above, the method of rotating the elastic member requires a short cleaning time, and is advantageous in image reading productivity. However, in this method, since the elastic member is rotationally driven only in one direction, there is a problem that the tip of the elastic member is deformed in the rotational direction due to long-term use and the cleaning function is deteriorated.

It is possible to correct the deformation by appropriately reversing the elastic member. However, if the elastic member is reversed, the foreign matter captured by the elastic member falls on the reading glass again or is pushed further upstream in the document transport direction from the reading position, and eventually the foreign matter remains on the reading glass and streaks in the read image. May cause noise.
JP 2000-270152 A

  Accordingly, an object of the present invention is to read an image which can prevent deterioration of the cleaning function due to deformation of the cleaning member by appropriately reversing the cleaning member and effectively prevent reattachment of foreign matter on the reading glass. To provide an apparatus.

In order to achieve the above object, an image reading apparatus according to an aspect of the present invention includes:
A document conveying means for sending out the documents one by one and passing the reading position;
Reading means for optically reading an image of the document conveyed at the reading position;
A transparent member disposed between the document conveyed at the reading position and the reading unit;
A cleaning member having elasticity for cleaning by rubbing the surface of the transparent member through which the document passes;
Said rotated forward to clean over said transparent member and the cleaning member from the upstream side in the transport direction of the document is conveyed by the document conveying means to the downstream side, and, to the upstream side from the downstream side of the transport direction driving means Ru is correct the deformity of the cleaning member is reversed and,
Control means for controlling rotation of the cleaning member via the drive means;
With
The control means rotates the cleaning member forward until the predetermined number of faces of the document is read, reverses the cleaning member after reading the predetermined number of faces of the document, and then Rotating the cleaning member forward before the document is conveyed to the reading position;
It is characterized by.

In the image reading apparatus, foreign matters can be removed from the reading position of the transparent member (reading glass) by rotating the cleaning member forward. The cleaning member is always driven to rotate in one direction, and it will be deformed to bend in the direction of rotation due to long-term use. However, the deformation is corrected by reversing the cleaning member after reading the predetermined number of faces of the document. Is done. Due to this reversal, the foreign matter captured by the cleaning member may fall on the transparent member again. However, after reversing the cleaning member, the cleaning member is rotated forward before the next document is conveyed to the reading position, thereby preventing foreign matter from reattaching and effectively removing it from the reading position. Can do.

  Embodiments of an image reading apparatus according to the present invention will be described below with reference to the accompanying drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same component and the same part, and the overlapping description is abbreviate | omitted.

(Image reader, see FIGS. 1 and 2)
As shown in FIG. 1, an image reading apparatus 10 according to an embodiment of the present invention is conveyed by a platen set method for reading an image of a document placed on a platen glass (not shown) and an automatic document conveying device 20. A reading optical system (scanner) 50 is installed.

  The reading optical system 50 is known per se and includes a lamp 53, mirrors 54, 55, and 56, an imaging lens (not shown), and an imaging unit (CCD color line sensor) 58. In order to read a document image by the platen set method, 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 each can move in the sub-scanning direction Y. . Reading of a document image by the sheet-through method is performed in a state where the optical system 50 is stationary at a reading position A shown in FIG.

  The automatic document feeder 20 includes a document placing tray 21, a pickup roller 22, a paper feed roller 23a and a separating roller 23b, a registration roller 24, reading unit rollers 25 and 26, discharge unit rollers 27 and 28, A document discharge tray 29 is included. A transparent member (hereinafter referred to as a reading glass 40) is installed at the reading position A.

  Further, in this embodiment, as shown in FIG. 2, the guide sheet 41 that guides the document so that the image surface does not contact the reading glass 40 directly above the reading glass 40 is upstream of the reading glass 40 in the conveyance direction B. It is installed on the side. The original conveyed on the reading glass 40 is guided by sliding on the guide sheet 41, so that the original is conveyed in a state where the image surface is not in contact with the surface of the reading glass 40.

  When the original is brought into contact with the reading glass 40, adhesive foreign matters (adhesives such as adhesive tape and glue, correction liquid lump, ink ball of a ballpoint pen, eraser powder, etc.) adhering to the original are read glass. 40 is transferred and adhered onto the substrate 40. By conveying the document to the reading glass 40 in a non-contact manner, such transfer and adhesion of foreign matter can be prevented in advance. Of course, in this embodiment, even if an adhesive foreign material adheres to the reading glass 40, it can be eliminated by the cleaning member 45 described below.

  In addition to providing the guide sheet 41, such non-contact conveyance is achieved by conveying the document while curving the document with a certain curvature by the reading unit rollers 25 and 26.

  Further, in this embodiment, it is also possible to invert the front and back of a document on which images are formed on both sides and pass the reading position A again to continuously read the front and back images. Such a double-sided reading mechanism for a document is well known and will not be described.

(See cleaning member, FIGS. 2-5)
As shown in FIG. 2, a brush-like cleaning member 45 is rotatably disposed facing the reading position A of the reading glass 40. Further, a striking member 46 is disposed downstream of the cleaning member 45 in the document conveyance direction B. The cleaning member 45 is a member in which a cleaning brush 45b that is elastically deformable on a flat surface of the shaft member 45a is fixed in a line shape in a direction perpendicular to the conveyance direction B. The motor M1 (refer to FIG. Driven forward or reverse at speed. A white reference discriminating member (white film) 45c may be attached to the outer peripheral surface of the shaft member 45a facing the cleaning brush 45b for shading correction.

  The cleaning brush 45b is, for example, a 6 mm long, 2D (denier) conductive (11.5 LogΩ) polyimide resin implanted in a width of 5 mm and a length of 309 mm, and is used when the reading glass 40 is rubbed. The amount of biting is set to 1.5 mm, and the pressure is set to 6N.

  The striking member 46 is fixed in position, and scrapes off foreign matter captured by the cleaning brush 45b after the cleaning brush 45b rubs on the reading glass 40.

  As shown in FIG. 3A, the cleaning member 45 stands by as a home position when the cleaning brush 45b faces upward, and an arrow c from the home position to the downstream side in the document transport direction. Start normal rotation in the direction. Thereafter, the tip of the brush 45b rubs the surface of the reading glass 40 (see FIGS. 3B and 3C), captures foreign matter on the reading glass 40, and removes the foreign matter from the reading position A. Thereafter, the brush 45b contacts the hammering member 46 and returns to the home position.

  The captured foreign matter is knocked out of the brush 45 b by the hitting member 46, is caught in a document conveyed on the reading glass 40, and is discharged to the outside of the apparatus 10. As a result, the surface of the reading glass 40 (in particular, the reading position A) and the brush 45b are always kept clean, and foreign matter collected from the reading glass 40 by the brush 45b does not adhere to the reading glass 40 again. Therefore, it is possible to prevent streak noise from occurring in the read image. It should be noted that the foreign matter knocked out from the brush 45b may be removed by suction by a suction means (not shown).

  The brush 45b has conductivity and is connected to the ground. Therefore, the foreign matter on the reading glass 40 can be electrostatically attracted and recovered efficiently.

  Here, the shape of the tip portion of the cleaning brush 45b will be described with reference to FIG. FIG. 4A shows a first example, in which the tip portions of the brush bristles are aligned to the same length up to the tangent line C of the rotation locus F. FIG. FIG. 4B shows a second example, in which the tip of each bristle is aligned with the rotation locus F. FIG. 4C shows a third example, in which the tip of each bristle has a length up to a straight line that forms an angle θ with the tangent C. FIG. 4 (D) shows a fourth example. The brush bristles consist of two bundles 45d and 45e, the brush bundle 45d has a length up to the tangent C, and the tip of the brush bundle 45e is along the rotation locus F. It is cut diagonally in a line.

  In the example shown in FIGS. 4B, 4 </ b> C, and 4 </ b> D, when the brush 45 b rotates and rubs on the reading glass 40, the tip of each bristle pops out from the rotation locus F. In other words, it is possible to keep the contact amount and contact pressure of the brush 45b to the reading glass 40 constant.

  By the way, the cleaning of the reading glass 40 by the cleaning member 45, that is, the normal rotation of the cleaning member 45 at the reading position A is performed at an arbitrary timing at which the brush 45b does not interfere with the original conveyed at the reading position A. For example, it is executed when reading of a plurality of images is started, when reading is completed, or while the reading glass 40 is exposed between the document to be conveyed.

  If the cleaning member 45 is always driven to rotate normally in one direction to clean the reading glass 40, the tip of the brush 45b is deformed to be curved in the rotational direction due to long-term use, and the cleaning function is deteriorated. In order to correct this deformation, in this embodiment, the cleaning member 45 is reversed at a predetermined timing described in the following control example. As a result of this reverse rotation, the cleaning brush 45b rubs against the hammering member 46 and the reading glass 40 in the reverse direction to receive the deformation force in the reverse direction, the deformation is corrected, and a good cleaning function is maintained for a long time.

  On the other hand, when the cleaning member 45 is reversed, the foreign matter taken in by the brush 45b falls on the reading glass 40 again or is pushed further upstream from the reading position A in the transport direction B, and the foreign matter remains on the reading glass 40 after all. This may cause streak noise in the read image. Therefore, in this embodiment, after the cleaning member 45 is reversed, the cleaning member is rotated forward before the next original is conveyed to the reading position A. As a result, it is possible to prevent the foreign matter from reattaching to the reading glass 40 and effectively remove the foreign matter from the reading position A. Details of forward and reverse control of the cleaning member 45 will be described later.

  Next, the drive means of the cleaning member 45 will be described with reference to FIG. The sprocket 31 fixed to one end of the shaft member 45a is connected to the output sprocket 32 of the cleaning motor M1 via the timing belt 33. The cleaning motor M1 is a stepping motor that can be driven forward and reverse.

  Further, an arc-shaped protruding piece 35 is attached to the sprocket 31, and a home position sensor SE2 for detecting the protruding piece 35 is disposed. When the sensor SE2 detects the end 35a of the protruding piece 35, it is detected that the cleaning brush 45b is located at the home position.

(Control unit, see FIG. 6)
The control unit of the image reading apparatus 10 will be described with reference to FIG. The control unit is configured with the CPU 60 as the center, and the CPU 60 includes a ROM 61, a RAM 62, and a memory 63 that store programs and the like. The information input to the CPU 60 includes the number of sheets read from the number counter 64 that counts the number of the scanned images, the leading edge and the trailing edge of the document from the document sensor SE1 (see FIG. 2) arranged upstream of the reading position A. Detection signal, a detection signal from the home position sensor SE2 of the cleaning member 45, and the like. Further, the CPU 60 controls a document conveying system such as various rollers, a cleaning motor M1, and the like.

(Outline explanation of control example)
Below, the example of control of the normal rotation of the cleaning member 45 and reverse rotation is demonstrated. First, the cleaning member 45 is reversed every predetermined number of reading surfaces (for example, 5 to 20 surfaces). If the prescribed number of readings is reached in the course of one job in which images of a plurality of documents are continuously read, the next document is placed on standby upstream of the reading position A, and the cleaning member 45 is rotated in the reverse and normal directions. (It will be described below as control example 1).

Also, if it reaches the reading surface number of provisions in the middle of one job continuously performing image reading of a plurality of originals, after reading the images of all the originals in one job, it reverses the cleaner 45 and Forward rotation (described below as control example 2).

  If the specified number of pages has been reached in the middle of one job in which images of a plurality of documents are continuously read, the cleaning member 45 is reversed immediately after reading all the images of the documents in one job. When the job is started, the cleaning member 45 is rotated forward (described below as control example 3).

When the specified number of pages has been reached in the middle of one job in which images of a plurality of documents are continuously read, when the next job is started after all the images of the documents in one job have been read. The cleaning member 45 is rotated reversely and forwardly (described below as a control example 4).

(Refer to Control Example 1 and FIG. 7)
In the control example 1, as shown in FIG. 7, when the document feeding is started (step S1) and the leading edge of the document is detected by the sensor SE1 (step S2), the count value of the surface number counter 64 is added. (Step S3), the count value is compared with the specified value (Step S4). The specified value is normally set to an arbitrary value between 5 and 20.

  When the count value reaches the specified value (YES in step S4), the conveyance of the next document is stopped (step S5), and the cleaning member 45 is reversed (step S6). Thereafter, the surface number counter 64 is reset (step S7), and the cleaning member 45 is rotated forward (step S8). Next, the conveyance of the next document is resumed (step S9), and if there is another document (YES in step S10), the process returns to step S1.

  On the other hand, if the count value has not reached the specified value (NO in step S4), the conveyance of the next original is continued and step S10 is executed.

(Refer to Control Example 2 and FIG. 8)
In the control example 2, as shown in FIG. 8, the document feeding is started (step S11), and when the leading edge of the document is detected by the sensor SE1 (step S12), the count value of the surface number counter 64 is added. (Step S13), the cleaning member 45 is rotated forward (Step S14). If there is a next original (YES in step S15), the process returns to step S11. If there is no next original (NO in step S15), that is, if reading of all originals is completed, the count value of the number counter 64 is compared with the specified value (step S16). The specified value is normally set to an arbitrary value between 5 and 20.

  If the count value has reached the specified value (YES in step S16), the cleaning member 45 is reversely rotated (step S17) and forwardly rotated (step S18). Thereafter, the surface number counter 64 is reset (step S19).

  On the other hand, if the count value has not reached the specified value (NO in step S16), the apparatus 10 is kept waiting until the next reading job and the count value of the number counter is held (step S20).

(Refer to Control Example 3 and FIG. 9)
In the control example 3, as shown in FIG. 9, first, the count value of the surface number counter 64 is compared with the specified value (step S21). The specified value is normally set to an arbitrary value between 5 and 20. If the count value has reached the specified value (YES in step S21), the cleaning member 45 is rotated forward (step S22), and the surface number counter 64 is reset (step S23). If the count value has not reached the specified value (NO in step S21), the process proceeds to the next step S24.

  Next, the feeding of the document is started (step S24), and when the leading edge of the document is detected by the sensor SE1 (step S25), the count value of the surface number counter 64 is added (step S26), and the cleaning member 45 is moved. Forward rotation (step S27). If there is a next original (YES in step S28), the process returns to step S24. If there is no next original (NO in step S28), that is, if reading of all originals is completed, the count value of the number-of-faces counter 64 is compared with the specified value (step S29).

  If the count value has reached the specified value (YES in step S29), the cleaning member 45 is reversed (step S30).

  On the other hand, if the count value has not reached the specified value (NO in step S29), the apparatus 10 is kept waiting until the next reading job and the count value of the number counter is held (step S31).

(Refer to Control Example 4 and FIG. 10)
In the control example 4, as shown in FIG. 10, first, the count value of the surface number counter 64 is compared with the specified value (step S41). The specified value is normally set to an arbitrary value between 5 and 20. If the count value has reached the specified value (YES in step S41), the cleaning member 45 is reversely rotated (step S42) and forwardly rotated (step S43). Then, the surface number counter 64 is reset (step S44). If the count value has not reached the specified value (NO in step S41), the process proceeds to the next step S45.

  Next, the feeding of the document is started (step S45). When the leading edge of the document is detected by the sensor SE1 (step S46), the count value of the surface number counter 64 is added (step S47), and the cleaning member 45 is moved. Forward rotation (step S48). If there is a next original (YES in step S49), the process returns to step S45. If there is no next original (NO in step S49), that is, if all the originals have been read, the control is ended.

(Cleaning member forward / reverse control)
When the time from the start of feeding the first document to the time when the leading edge of the document reaches the reading position A is Ta, and the time from the reverse of the cleaning member 45 to the normal rotation is Tb, Ta When> Tb, the cleaning member 45 may be reversely rotated and rotated forward during the time Ta, and when Ta ≦ Tb, the cleaning member 45 may be controlled not to operate during the time Ta.

  Since reading at a high resolution has a relatively low document conveyance speed, Ta> Tb, and there is room for the cleaning member 45 to be reversed and rotated forward. On the other hand, since reading at a low resolution has a relatively high document conveyance speed, Ta <Tb, and there is no room for reverse and forward operations of the cleaning member 45. Therefore, the reverse operation is not performed in the latter case. However, the forward rotation operation for cleaning can be executed.

(Number of reverse rotations)
Further, the cleaning member 45 may be continuously reversed several times, and the number of reverse rotations is preferably changed, for example, as shown in FIG. Thus, it is possible to effectively correct the deformation of the brush 45b caused by continuing the forward rotation operation.

(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.

  For example, in the above-described embodiment, the document is conveyed in a non-contact manner with respect to the reading glass, but it is not always necessary to convey the document in a non-contact manner. Further, the striking member for the cleaning member is optional in its configuration and operation, and may be omitted.

It is a schematic block diagram which shows one Example of the image reader which concerns on this invention. It is sectional drawing which shows the vicinity of an image reading position. It is explanatory drawing which shows the cleaning operation | movement of the reading glass by a cleaning member. It is explanatory drawing which shows the various brush shape of a cleaning member. It is a perspective view which shows the drive means of the cleaning member. It is a block diagram which shows the control part of an image reading apparatus. It is a flowchart figure which shows the example 1 of control. It is a flowchart figure which shows the example 2 of control. It is a flowchart figure which shows the example 3 of control. It is a flowchart figure which shows the example 4 of control. It is a graph which shows the frequency | count of reverse rotation with respect to the normal rotation accumulation frequency of a cleaning member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image reading device 20 ... Automatic document feeder 40 ... Reading glass 45 ... Cleaning member 45b ... Cleaning brush 50 ... Reading optical system 60 ... CPU
M1 ... Cleaning motor A ... Reading position B ... Original transport direction

Claims (8)

A document conveying means for sending out the documents one by one and passing the reading position;
Reading means for optically reading an image of the document conveyed at the reading position;
A transparent member disposed between the document conveyed at the reading position and the reading unit;
A cleaning member having elasticity for cleaning by rubbing the surface of the transparent member through which the document passes;
Said rotated forward to clean over said transparent member and the cleaning member from the upstream side in the transport direction of the document is conveyed by the document conveying means to the downstream side, and, to the upstream side from the downstream side of the transport direction driving means Ru is correct the deformity of the cleaning member is reversed and,
Control means for controlling rotation of the cleaning member via the drive means;
With
The control means rotates the cleaning member forward until the predetermined number of faces of the document is read, reverses the cleaning member after reading the predetermined number of faces of the document, and then Rotating the cleaning member forward before the document is conveyed to the reading position;
An image reading apparatus.   The image reading apparatus according to claim 1, wherein the cleaning member is a brush, and at least a portion of the brush that contacts the transparent member is less rigid than the transparent member and elastically deforms by contact.   The control means waits for the next original on the upstream side of the reading position when the predetermined number of reading faces is reached in the course of one job in which images of a plurality of the originals are continuously read. The image reading apparatus according to claim 1, wherein the member is rotated reversely and forwardly.   The control means reads all the images of the originals in the one job even when the specified number of reading faces is reached in the middle of one job in which the image reading of a plurality of the originals is continuously performed. The image reading apparatus according to claim 1, wherein the cleaning member is rotated backward and forward after the cleaning.   The control means reads all the images of the originals in the one job even when the specified number of reading faces is reached in the middle of one job in which the image reading of a plurality of the originals is continuously performed. 3. The image reading apparatus according to claim 1, wherein the cleaning member is reversely rotated immediately after the rotation, and the cleaning member is rotated forward when the image reading of the original is started next.   The control means reads all the images of the originals in the one job even when the specified number of reading faces is reached in the middle of one job in which the image reading of a plurality of the originals is continuously performed. 3. The image reading apparatus according to claim 1, wherein when the image reading of the original is started next, the cleaning member is rotated reversely and forwardly. 4.   The control means sets Ta as the time from the start of feeding the first original to the reading position until the leading edge of the original reaches the reading position, and Tb as the time from the reverse of the cleaning member to normal rotation. When Ta> Tb, the cleaning member is reversely rotated and rotated forward during the time Ta, and when Ta ≦ Tb, the cleaning member is not rotated reversely and forwardly during the time Ta. The image reading apparatus according to claim 1.   The image reading apparatus according to claim 1, wherein the control unit increases the number of times the cleaning member is reversely rotated in accordance with a cumulative number of normal rotations of the cleaning member.

Images