JP3714277B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus that is compact and low-cost and capable of reading images on both sides of a document at high speed.
[0002]
[Prior art]
Some scanners, facsimiles, copiers, and the like are equipped with an image reading device that automatically and sequentially feeds a bundle of sheet-like documents such as paper and reads an image of each document. In general, the image reading apparatus includes a sheet fixing type that temporarily fixes and reads sequentially supplied documents, and a sheet through type that reads a document conveyed without fixing the document.
[0003]
The sheet fixing type image reading apparatus supplies, for example, the uppermost or lowermost original from a bundle of originals placed on a paper feed tray onto a platen glass such as a flatbed scanner by a pickup roller and a conveyor belt. Once the original is stopped on the platen glass, the scanner below the platen glass is moved to read the image information of the original, and the original after reading is discharged to the paper discharge tray, and the original to be read next is read. Similarly, the image of each original is automatically and sequentially read by supplying image data from the paper feed tray onto the platen glass and repeating the reading of the image information by the scanner.
[0004]
On the other hand, in the sheet-through type image reading apparatus, the scanner is stopped in advance under the platen glass, and sequentially conveyed onto the platen glass from the bundle of documents placed on the paper feed tray by the pick-up roller and the conveyance roller. The original to be read is read by the scanner.
[0005]
The sheet fixing type image reading apparatus temporarily stops the conveyed document at a predetermined position on the platen glass and then moves the scanner to read the document. There is a drawback in that the processing time is long compared to the sheet-through type image reading apparatus that reads a time lag and a time for returning the scanner to the initial position without stopping the document. This drawback becomes more conspicuous when reading both sides of a document automatically.
[0006]
Therefore, an image reading apparatus capable of reading both sides of a document often adopts a sheet-through type, and a conventional sheet-through type image reading apparatus is disclosed in, for example, JP-A-7-175279. There is.
[0007]
18 to 20 are schematic diagrams for explaining the outline of a conventional sheet-through type image reading apparatus 800. As shown in FIG. 18, the image reading apparatus 800 has a bundle of documents to be read. A paper feed tray 80, a pickup roller 81a for taking out the uppermost document from the paper feed tray, a paper feed roller 81b for feeding the document to the transport path 82, and transport for transporting the document in the transport path 82. A roller 81c, a platen glass 83 disposed below the conveyance path, a reduction optical system scanner 84 composed of a CCD or the like for reading an original through the platen glass 83, and a paper discharge roller for reversely feeding and discharging the original. 81d.
[0008]
The conveyance path 82 allows the original supplied from the paper feed tray 80 to pass over the platen glass 83 while being inverted downward, and is further discharged from below the paper feed tray 80 to a paper discharge tray (not shown). It is curved in a substantially U shape so as to be guided, and further, a return path 85 is provided in the transport path 82, which leads from the downstream side to the upstream side of the platen glass 83.
[0009]
Further, a document set sensor 86a, a lead sensor 86b, and a reversing sensor 86c that detect the presence or absence of a document and output a detection signal are arranged at required positions on the conveyance path 82, and are based on the detection signals of the sensors. Thus, the operation of a motor or clutch that rotates the pickup roller 81a, the paper feed roller 81b, the transport roller 81c, or the paper discharge roller 81d, or the reading operation of the scanner 84 is controlled.
[0010]
As shown in FIG. 18, the bundle of documents placed on the paper feed tray 80 has a top surface as a front surface. After the front surface is first read, the back surface of the same document is read, and the next document The front and back are sequentially read. In each figure, the first side, the second side,... Are shown in the document according to the reading order.
[0011]
From the bundle of documents placed on the paper feed tray 80, the uppermost document is taken out by the pickup roller 81 a and supplied to the conveyance path 82 by the paper feed roller 81. The document is conveyed by the conveyance roller 81c so as to be reversed in the conveyance path 82, and when passing over the platen glass 83, the scanner 84 reads the image of the document surface, that is, the first surface. The document whose first surface has been read is further transported, and the discharge roller 81d stops with the rear side in the transport direction of the document held between the nip surfaces of the discharge roller 81d, as shown in FIG. .
[0012]
The sheet discharge roller 81d rotates in the reverse direction while the document is held, and the document whose first surface is read is conveyed to the return path 85 as shown in FIG. The original returns from the return path 85 to the conveyance path 82 on the upstream side of the platen glass 83. Similarly, the original is conveyed so as to be reversed downward in the conveyance path 82 and passes over the platen glass 83. Thus, the image on the second surface is read.
[0013]
The document whose first surface and second surface are read is further conveyed, and as shown in FIG. 20 (a), the discharge roller with the rear side in the conveyance direction of the document held between the nip surfaces of the discharge roller 81d. 81d stops. At this stage, scanning of both sides of the document has been completed. However, when the document is discharged to the discharge tray as it is, the first surface becomes the upper surface, and the read documents are sequentially stacked on the upper surface side. The page order placed on the tray 80 is not aligned. Accordingly, the paper discharge roller 81d is reversed again to send the original to the return path 85, and similarly, the conveying path 82 is conveyed so as to be reversed downward, and as shown in FIG. The sheet is discharged to the sheet discharge tray so that the surface becomes the lower surface. In this way, it is possible to sequentially take out originals from a bundle of originals and read images on both sides of the originals.
[0014]
[Problems to be solved by the invention]
However, in the image reading apparatus 800, it is necessary to invert the original in order to read the second side of the original and further invert the original in order to align the pages of the read original, and the control mechanism is complicated. Since the transport distance is also long, there is a drawback that the document is likely to be skewed during the transport and easily jammed. Further, since the original to be read next cannot be supplied to the conveyance path 82 until the second reversal of the original is completed, there is a disadvantage that a reading time several times that of normal one-side reading is required.
[0015]
On the other hand, a reading unit that reads the front surface of the document and a reading unit that reads the back side of the document are arranged at substantially opposite positions on the document transport path, and the images read simultaneously on the front and back surfaces of the document transported on the transport path in one transport. A reading device has also been proposed (Japanese Patent Laid-Open No. 1-194658). However, in order to simultaneously read the first side and the second side of the document, an image memory for temporarily storing the read image data and an image processing circuit for performing shading processing of the image data are provided for each reading unit. There is a problem that the cost of the image reading apparatus becomes high.
[0016]
The present invention has been made in view of these problems, and provides an image reading apparatus capable of reading both sides of an original, shortening the reading time of the original, and simple and low-cost. The purpose is to provide.
[0017]
Another object of the present invention is to provide an image reading apparatus capable of sharing an image processing circuit for processing each image data read on both sides with each scanner.
[0018]
[Means for Solving the Problems]
An image reading apparatus according to the present invention includes a transport unit that transports a document placed on a paper feed tray to a paper discharge tray via a substantially U-shaped transport path, and is disposed in the transport path from the paper feed tray. A first reading unit that reads an image on the first surface of the document that is being reversed and conveyed, and a first reading unit that is disposed on a conveyance path on the opposite side and downstream of the first reading unit. In an image reading apparatus comprising a second reading means for reading an image on two sides, the distance of the conveyance path between the reading position of the first reading means and the reading position of the second reading means should normally be read A retract path for retracting a document transported in the reverse direction that is longer than the length of the document is substantially U-shaped upward after branching from the transport path between the first reading means and the second reading means. Curved to the upper side of the second reading means and the casing of the image reading device The first detection is provided so as to communicate with the formed retraction opening, and is provided at a predetermined position on the upstream side of each of the first reading means and the second reading means at a distance slightly longer than the normal reading size. When the length of the document to be read detected by the first detection unit and the second detection unit is equal to or shorter than the distance of the conveyance path between the reading position of the first reading unit and the reading position of the second reading unit. After the reading of the first reading unit, the document is further conveyed by the conveying unit and read by the second reading unit, and the length in the conveying direction of the document to be read is the distance If the length is longer, after the reading of the first reading means is completed, the trailing edge of the original is detected by the second detecting means upstream of the reading position of the second reading means, and then the leading edge of the original is detected by the conveying means. Detected by the second detection means Control means is provided for controlling the second reading means to read after being conveyed in the reverse direction while being retreated in a substantially U shape to the retraction path until known. Is.
As a result, when reading a double-sided document below the document to be normally read, the image reading of the first reading unit and the image reading of the second reading unit do not overlap.
[0019]
Further, according to the present invention, the first detection means detects a document being conveyed and outputs a detection signal in order to control the start and end of image reading of the first reading means, and the second detection means In order to control the start and end of image reading by the second reading means, the conveyed document is detected and a detection signal is output.
[0020]
Here, the document to be normally read is set in advance according to the purpose for which the image reading apparatus is used. For example, in a general office where an office document is often used as a document, the image is to be read. When using the reading device, it is preferable to set the document to be normally read as an A4 size (JIS standard A row No. 4: 210 mm × 297 mm).
[0021]
An A4 size document may be read vertically or horizontally, but the distance between the conveyance paths can be shortened by setting the document conveyance direction to the horizontal direction. This is preferable because the image reading apparatus can be made more compact. The distance between the conveyance paths at that time is 210 mm or more.
[0022]
According to the present invention, in the image processing apparatus, an image processing circuit that performs image processing of image data read by the first reading unit and the second reading unit is provided. As described above, since the image reading of the first reading unit and the second reading unit does not overlap, it is possible to simplify the configuration of the image reading apparatus assuming that one image processing circuit is shared.
[ 0023 ]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an image reading apparatus according to an embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the configuration of the image reading apparatus 100, and FIG. 2 is a block diagram showing the control of the image reading apparatus 100.
[ 0024 ]
As shown in the drawing, the image reading apparatus 100 includes a paper feed tray 101 on which a bundle of documents to be read is placed, a pickup roller 102a that takes out and supplies the top sheet from the bundle of documents, a separation roller 102b, A retard roller 102 c, a conveyance path 104 that guides the supplied document to the paper discharge tray 103 while being reversed downward, a conveyance roller 105 that is appropriately disposed in the conveyance path 104 and conveys the document, and the most downstream of the conveyance path 104 A discharge roller 106 disposed on the side for discharging the original, a first reading unit (first reading means) 107 disposed at a predetermined position on the conveyance path 104, and a downstream side of the first reading unit 107. A second reading unit (second reading means) 108 and a branch path from the conveyance path 104 between the first reading unit 107 and the second reading unit 108 are provided. Was those formed by and a retracting path 109. Further, a document set sensor 110 that detects the presence or absence of a document on the paper feed tray 101, a first lead sensor (first detection means) 111 that detects a document at a predetermined position upstream of the first reading unit 107, and a first And a second read sensor (second detection means) 112 for detecting a document at a predetermined position upstream of the two reading unit 108.
[ 0025 ]
FIG. 2 is a block diagram showing the control of the image reading apparatus 100. The image reading control unit (control means) detects each of the document set sensor 110, the first lead sensor 111, and the second lead sensor 112. Based on the signal, the first reading unit (scanner) 107 and the second reading unit (scanner) 108, a paper feed motor, a paper feed clutch, and the like are controlled. Further, the image reading apparatus 100 is mounted on a main body having a function of a well-known and arbitrary facsimile machine and copying machine, and the configuration of the main body will not be described in detail. The image data read by the 107 and the second reading unit 108 is output to the main body control unit and is transmitted by the printer via printing or CODEC. Although the figure shows a configuration in which an image reading control unit is provided in addition to the main body control unit, the main body control unit controls the first reading unit 107 and the second reading unit 108, a paper feed motor, a paper feed clutch, and the like. It is also possible to adopt a configuration.
[ 0026 ]
The paper feed tray 101 is provided at an upper portion of the image reading apparatus 100 so as to be inclined in a direction in which a document is supplied, and a bundle of documents is placed so as to be aligned with the inclined lower end side of the paper feed tray 101. The A pickup roller 102 a, a separation roller 102 b, and a retard roller 102 c are arranged in the vicinity of the inclined lower end side of the sheet feeding tray 101, and these and the conveying roller 105 constitute a document conveying unit.
[ 0027 ]
The pickup roller 102 a is for taking out the uppermost paper of the document placed on the paper feed tray 101, is pivotally supported by the swing arm 20, and can be brought into contact with and separated from the bottom surface of the paper feed tray 101. . The swing arm 20 swings up and down by a paper feed clutch (not shown), and the pickup roller 102a is separated from the paper feed tray 101 in a normal state such as when a document is placed. It is lowered so as to come into contact with the uppermost sheet of the document placed when the document is taken out. Since the pickup roller 102a can be lowered until it comes into contact with the bottom surface of the paper feed tray 101, the pickup roller 102a can always come into contact with the uppermost paper even if the thickness of the bundle of documents changes depending on the number of documents.
[ 0028 ]
On the other hand, the separation roller 102b and the retard roller 102c are arranged so that the surfaces of the respective rollers nip, and the separation roller 102b sends the document taken out by the pickup roller 102a to the conveyance path 104 at a constant speed. The retard roller 102c rotates in the direction opposite to the conveyance direction to reliably separate the uppermost sheet from the bundle of documents.
[ 0029 ]
The pickup roller 102a, the separation roller 102b, and the retard roller 102c are rotated by an unillustrated paper feed motor through appropriate gears, and the presence or absence of the document on the paper feed tray 101 is determined by the document setting. Based on the detection signal, the image reading control unit controls the operations of the pickup roller 102a, the separation roller 102b, and the retard roller 102c.
[ 0030 ]
The conveyance path 104 is a substantially U-shaped conveyance path that allows the paper feed tray 101 and the document discharge tray 103 to communicate with each other, and the document supplied from the paper feed tray 101 is inverted downward by the conveyance path 104. Are guided onto the first reading unit 107. That is, the upper surface of the paper feed tray 101 is the lower surface, and this surface is read by the first reading unit 107.
[ 0031 ]
In the conveyance path 104, a conveyance roller 105 for conveying the document is appropriately disposed. The conveying roller 105 is provided with a pair of a rotating roller rotated by a motor and a driven roller driven by the rotation of the roller at an opposing position so as to sandwich the conveying path 104. A discharge roller 106 is provided on the most downstream side of the conveyance path 104. Similarly, the discharge roller 106 is provided so that a pair of a rotation roller and a driven roller sandwich the conveyance path 104. In FIG. 1, five transport rollers 105 and two discharge rollers 106 are arranged in the transport path 104, but depending on the shape and distance of the transport path 104, the transport rollers 105 and the discharge rollers 106 are appropriately set. It can be increased or decreased.
[ 0032 ]
The first reading unit 107 includes a transparent platen glass 70 provided so as to be close to the conveyance path 104, a light source 71 that irradiates light on a document conveyed on the conveyance path 104 through the platen glass 70, and a document A reflection mirror 72 for guiding reflected light from the light in a predetermined direction, a lens 73 for converging the reflected light, and a charge coupled device 74 (hereinafter referred to as “CCD”) for converting the converged light into an electric signal. ), And is a movable image reading means disposed so as to be movable in the horizontal direction below the conveyance path 104, as shown in the figure.
[ 0033 ]
That is, the first reading unit 107 is used in combination with a reading unit of a flat bed scanner. When reading a document with the flat bed, the first reading unit 107 moves in the horizontal direction below the flat bed portion to read the document. Is read below the platen glass 70. In this manner, the images of the original document that is conveyed on the conveyance path 104 and passes immediately above the platen glass 70 are sequentially read.
[ 0034 ]
A first read sensor 111 is disposed at a predetermined position upstream of the first reading unit 107, detects a document conveyed on the conveyance path 104, and an image reading control unit detects the document on the basis of the detection signal. The document reading operation of the first reading unit 107 is controlled. That is, the first reading unit 107 starts reading an image after a predetermined count after the first read sensor 111 detects the presence of a document, and the first reading unit after a predetermined count after the first read sensor 111 detects the absence of the document. 107 finishes image reading.
[ 0035 ]
The second reading unit 108 is a so-called contact image sensor (hereinafter referred to as “CIS”). Although not shown in detail in the drawing, the second reading unit 108 converges reflected light from a document irradiated by a light source. It is a fixed reading means that converges and reads on the photoconductive element with a fiber. As shown in the drawing, the second reading unit 108 is disposed on the conveyance path 104 on the opposite side of the first reading unit 107 and on the downstream side of the first reading unit 107, thereby the first reading unit 107. The original image on the side opposite to the unit 107 is sequentially read.
[ 0036 ]
Here, the CIS employed in the second reading unit 108 generally has a shallow depth of field of about several tenths of a millimeter, so that, for example, an image is read while a document is nipped by a platen roller (not shown). It has become. However, document flickering is likely to occur at positions where the conveyance path 104 is curved, and the image read by the second reading unit 108 may be distorted. Further, as described above, since the gap between the CIS and the platen roller is very narrow, jamming is likely to occur if the document is guided to the gap in a curved state. Therefore, in the second reading unit 108, the position where the conveyance path 104 is linear, in particular, as shown in the figure, the conveyance path 104 is horizontal for a certain distance, and the document is conveyed linearly without being curved. It is preferable to dispose at a position to be placed.
[ 0037 ]
A second read sensor 112 is disposed at a predetermined position upstream of the second reading unit 108, and, similar to the first reading unit 107, image reading is performed based on a detection signal from the second read sensor 112. The control unit controls the document reading operation of the second reading unit 108. In the present embodiment, a compact CIS is adopted as the second reading unit 108, but a CCD image sensor can be adopted as in the first reading unit 107.
[ 0038 ]
The distance of the conveyance path 104 between the reading position of the first reading unit 107 and the reading position of the second reading unit 108, and between the detection position of the first lead sensor 111 and the detection position of the second lead sensor 112. The distance of the conveyance path 104 is equal to or longer than the length of the document that the image reading apparatus 100 should normally read. The length of a document to be normally read varies depending on the purpose of use of the image reading apparatus 100, but when used for general office work, the document to be normally read should be A4 size and the transport direction should be a horizontal direction. That is, it is preferable that the distance is 210 mm or more. As described above, the distance of the conveyance path 104 between the detection position of the first lead sensor 111 and the detection position of the second lead sensor 112 is sufficiently secured to be 210 mm or more, so that the first reading unit 107 and the second reading unit are connected. The units 108 are also sufficiently separated from each other so that the original reading of the first reading unit 107 and the second reading unit 108 does not overlap when reading an A4 size or smaller original, and the first reading unit 107 and the second reading unit 108 are not duplicated. These light sources do not interfere with each other.
[ 0039 ]
As shown in the drawing, the retreat path 109 branches from the conveyance path 104 between the first reading unit 107 and the second reading unit 108, curves upward and reaches the upper side of the second reading unit 108. It has become. Here, it is preferable that the branch point of the retreat path 109 is upstream of the second lead sensor 112 and the forward / reverse rotation of the discharge roller 106 is controlled by the detection signal of the second lead sensor 112.
[ 0040 ]
A retraction port 91 is formed in the casing of the image reading apparatus 100 and communicates with the retraction path 109. As a result, a part of the document retracted to the retracting path 109 can project from the retracting port 91. When the document is retracted to the retreat path 109, the document is reversely fed until the leading end of the document is upstream of the second lead sensor 112. In this case, the distance from the second read sensor 112 to the rear end of the retreat path 109 needs to be longer than the length of the largest document in the conveyance direction to be read by the image reading apparatus 100. Is projected from the retraction opening 91, so that the retraction path 109 can be shortened and the image reading apparatus 100 can be made more compact.
[ 0041 ]
When the retract path 109 is stored in the casing of the image reading apparatus 100, the maximum length of a document to be read varies depending on the purpose of use of the image reading apparatus 100, but when used for general office work. It is preferable that the maximum size of the document to be read is A3 size (JIS standard A row 3), the transport direction is the horizontal direction, and the distance is 420 mm or more.
[ 0042 ]
Similarly to the conveyance path 104, the retraction path 109 is provided with a retraction roller 113 for conveying the document. The retracting roller 113 has the same configuration as the conveying roller 105, and a pair of a rotating roller and a driven roller is disposed so as to sandwich the retracting path 109.
[ 0043 ]
FIG. 3 is an enlarged view of the vicinity of the branch point of the retreat path 109. As shown in the drawing, a blade-shaped guide member 90 that can be elastically deformed is provided at the branch point of the transport path 104 and the retreat path 109. It has been. The guide member 90 is a thin piece that is wide in the width direction of the transport path 104, and is fixed so as to protrude obliquely downward from the upper side of the branch point of the transport path 104 toward the downstream side of the transport path 104. In the state, the tip is in contact with the bottom surface of the conveyance path 104.
[ 0044 ]
The guide member 90 arranged in this way is difficult to deform from the normal state to the upstream side because its tip abuts against the bottom surface of the conveyance path 104, but easily deforms to the downstream side. It is. Therefore, the document conveyed from the upstream side to the downstream side (in the right direction in the drawing) passes through the branch point by elastically deforming the guide member 90 by contacting the guide member 90 at the branch point. On the other hand, the original conveyed from the most downstream side of the conveying path 104 to the upstream (in the left direction in the figure) abuts on the guide member 90, but the guide member 90 does not elastically deform and guides the original to the retreat path 109. Is done.
[ 0045 ]
The guide member 90 is an example. For example, instead of the guide member 90, a guide plate capable of swinging around a branch point is provided, and a drive unit such as a solenoid moves the transport path 104 side or the retreat path 109 side. The document to be conveyed may be guided to the conveyance path 104 or the retreat path 109. By adopting the guide plate, it is possible to convey a soft or thin document that does not have sufficient strength to elastically deform the guide member 90.
[ 0046 ]
Further, in the present embodiment, the retreat path 109 is branched upward in a substantially U shape from the conveyance path 104, but the retreat path 109 can be an arbitrary path according to the free space of the image reading apparatus 100. Is possible. For example, the evacuation path 109 is bent downward in a U shape as shown in FIG. 4A, or branched in a direction opposite to the discharge direction of the conveyance path 104 as shown in FIG. 4B. It can also be In addition, when a manual document path is separately provided in the conveyance path 104, a part of the path may be shared with the path.
[ 0047 ]
Hereinafter, the operation of the image reading apparatus 100 will be described with reference to the drawings.
The operation of the image reading apparatus 100 is different depending on whether it is a size smaller than the original size to be read or not, and FIGS. 5 and 6 are flowcharts showing the operations of the image reading apparatus 100. FIGS. 7 to 12 are schematic diagrams showing a document conveyance state in each operation.
[ 0048 ]
FIG. 13A is a schematic diagram for explaining a document placed on the paper feed tray 101 and a reading order. In the image reading apparatus 100, a document is sequentially placed from the topmost sheet of the placed document. The upper surface is read as the first surface by the first reading unit 107 and the lower surface is read by the second reading unit 108 while being taken out and placed on the paper feed tray 101. Accordingly, as shown in the figure, a bundle of n originals is read sequentially from the upper surface of the uppermost sheet as the first surface, the second surface,..., And the upper surface of the lowermost sheet is the first ( The 2n-1) plane and the lower plane are read as the (2n) plane by the first reading unit 107 or the second reading unit 108, respectively, and the image reading is finished.
[ 0049 ]
Note that the reading order in the present embodiment is an example. For example, as shown in FIG. 13B, it is of course possible to sequentially read out and read from the bottom sheet, and the reading order in that case is also possible. The upper surface of the bottom paper is the first surface, the lower surface is the second surface, the upper surface of the uppermost paper is the second (2n-1) surface, and the lower surface is the second n surface, respectively. Reading is performed by the first reading unit 107 or the second reading unit 108.
[ 0050 ]
First, before reading an image, the size of a document to be read in advance is input in the operation unit, and the length of the document to be read in the conveyance direction of the image reading apparatus 100 is the reading position of the first reading unit 107 and the second reading unit 108. The transport method is selected depending on whether the distance is longer than the distance of the transport path 104 to the reading position, that is, whether the document is A4 size or less. Hereinafter, the image reading operation when the document is A4 size or smaller will be described with reference to FIGS. 5 and 7 to 9.
[ 0051 ]
When the start button of the operation unit is pressed, the image reading apparatus 100 starts reading an image of a document. The document set sensor 110 detects whether or not a document is placed on the paper feed tray 101 (S1). When the document set sensor 110 outputs a detection signal (ON) indicating that a document is placed, Based on the detection signal, the image reading control unit operates the paper feeding clutch (S2), and the swing arm 20 is lowered and the pickup roller 102a is placed on the uppermost sheet of the paper feeding tray 101 as shown in FIG. Abut.
[ 0052 ]
When the motor further rotates (S3), the pickup roller 102a, the separation roller 102b, the retard roller 102c, and the transport roller 105 rotate, and as shown in FIG. The roller 102c separates only one uppermost original, and the original is sent to the conveyance path 104 by the separate roller 102b. The conveyance roller 105 conveys the document along the conveyance path 104.
[ 0053 ]
As shown in FIG. 8A, the first read sensor 111 detects the leading edge of the conveyed document and outputs (turns on) a detection signal (S4), and the image reading control unit outputs the detection signal. After the reception, after a predetermined time has elapsed (after T1 conveyance, S5), as shown in FIG. 8B, image reading of the first reading unit 107 is started (S6). The predetermined time (T1 conveyance) is performed until the detected leading edge of the document reaches the reading position of the first reading unit 107 according to the conveyance distance and the conveyance speed from the first read sensor 111 to the first reading unit 107. For example, it is possible to control by the count number of the stepping motor that rotates the conveyance roller 105. Similarly, after the first read sensor 111 detects (turns off) the trailing edge of the document being conveyed (S7), the image of the first reading unit 107 is detected after a predetermined time has elapsed (S8 after T2 conveyance). Reading is terminated (S9).
[ 0054 ]
Further, the document is transported along the transport path 104 and reaches a branch point with the retreat path 109, but as shown in FIG. 3, the document comes into contact with the guide member 90 provided on the retreat path 109 to guide the document. The member 90 is pressed by the original and is elastically deformed downstream, so that the original can pass through the branch point in the direction of the conveyance path 104. Accordingly, as shown in FIG. 9A, the document is conveyed through the conveyance path 104 as it is without being guided to the retreat path 109.
[ 0055 ]
Thereafter, the second read sensor 112 detects the leading edge of the conveyed document (S10). The second read sensor 112 detects the leading edge of the document being conveyed and outputs a detection signal (ON), and the image reading control unit receives the detection signal and then passes a predetermined time (after T3 conveyance, S11). 9 (b), image reading of the second reading unit 108 is started (S12), and the second read sensor 112 detects (turns off) the trailing edge of the conveyed document. From (S13), the image reading of the second reading unit 108 is finished (S15) after a lapse of a predetermined time (T14 transport, S14).
[ 0056 ]
Here, since the document to be read is A4 size or smaller, as shown in FIG. 9A, the second read sensor 112 detects the leading edge of the document being conveyed, and the second reading unit 108 detects the document. When reading the second surface, the trailing edge of the document has already passed the reading position of the first reading unit 107. Therefore, since the image reading of the first reading unit 107 and the image reading of the second reading unit 108 do not overlap, the image processing circuit can be shared by the first reading unit 107 and the second reading unit 108.
[ 0057 ]
FIG. 14 is a block diagram illustrating an example of a circuit configuration until image data read by the first reading unit 107 and the second reading unit 108 is output to the main body control unit. The image data read by the second reading unit 108 is converted into digital data by the A / D conversion circuit and stored in the line memory, and the image data is subjected to image processing such as shading processing by the image processing circuit. It is configured to be output to the main body control unit.
[ 0058 ]
As described above, since the image reading of the first reading unit 107 and the image reading of the second reading unit 108 do not overlap, for example, the image data on the first surface and the image data on the second surface are processed simultaneously. Therefore, it is possible to switch and use one image processing circuit to sequentially process the image data of the first surface and the image data of the second surface and output them to the main body control unit. Thereby, the circuit configuration of the image reading apparatus 100 can be simplified and the cost can be reduced. For example, by outputting a signal for instructing the changeover switch to the A / D conversion circuit and the line memory, the A / D conversion circuit and the line memory are also connected between the first image reading unit 107 and the second image reading unit 108. It can be shared.
[ 0059 ]
The document on which the image reading on both sides has been completed is discharged to the discharge tray 103 by the discharge roller 106. Further, when the next document is present in the paper feed tray 101 (S16), the paper feed clutch is activated (S2), and the same operation as described above is repeated, and the document placed on the paper feed tray 101 is repeated. Documents are sequentially taken out from the bundle, and image reading from the first side to the nth side is performed. Of course, it is also possible to carry the next document into the conveyance path 104 before completely reading the both sides of the document.
[ 0060 ]
Further, the document whose image reading has been completed is discharged with the upper side of the original placed on the paper feed tray 101 being the lower side of the paper discharge tray 103, and the subsequent originals are similarly discharged. Since the sheets are stacked on the paper discharge tray 103, the page order of the bundle of discharged originals is the same as that on the paper supply tray 101.
[ 0061 ]
Next, with respect to image reading when the document to be read is larger than A4 size, for example, B4 size (JIS standard B row No. 4) or A3 size (JIS standard A row No. 3), FIGS. 12 will be described. As described above, the image reading apparatus 100 starts reading an image of a document by inputting the size of the document to be read in advance on the operation unit and then pressing the start button on the operation unit. The document set sensor 110 detects (turns on) that a document is placed on the paper feed tray 101 (S20), and the image reading control unit operates the paper feed clutch and the like (S21), so that the topmost document Only one sheet is separated and conveyed on the conveyance path 104 (S22), and the first read sensor 111 detects (turns on) the leading edge of the conveyed document (S23), and after a predetermined time has elapsed (after T1 conveyance). , S24), and until the image reading of the first reading unit 107 is started (S25), as described above, is the same as the case where the document is A4 size or smaller.
[ 0062 ]
In addition, after the first read sensor 111 detects (turns off) the trailing edge of the conveyed document (S26), the first reading unit 107 reads the image after a predetermined time has elapsed (T2 transported, S27). Although the process ends (S28), since the original to be read is larger than the A4 size, as shown in FIG. 10A, when the first read sensor 111 detects the trailing edge of the conveyed original. In addition, the leading edge of the document reaches the detection position of the second lead sensor 112. That is, the state in which the first lead sensor 111 detects a document (on state) and the state in which the second lead sensor 112 detects a document (on state) overlap. In this state, even when the second read sensor 112 detects the leading edge of the document, the image reading control unit does not start the image reading of the second reading unit 108.
[ 0063 ]
After the image reading of the first reading unit 107 is completed (S28), the second reading sensor 112 detects the trailing edge of the document as shown in FIG. The document is conveyed on the conveyance path 104 until it is detected (S29). When the second read sensor 112 receives a detection signal (OFF) that detects the trailing edge of the document, the image reading control unit reversely rotates the paper discharge roller 106 and the retracting roller 113 (S30). As a result, the document is fed back along the conveyance path 104, and the second read sensor 112 detects (turns on) the document again.
[ 0064 ]
The reversely fed document reaches a branch point with respect to the retreat path 109, and the leading end (reverse feed direction) of the document contacts the guide member 90 provided at the branch point. However, as shown in FIG. The member 90 guides the document to the retreat path 109 without elastic deformation. As a result, as shown in FIG. 11A, the leading edge (backward direction) of the reversely fed document is retracted to the retract path 109 and does not reach the reading position of the first reading unit 107. Therefore, while the image reading by the first reading unit 107 is completed and the original is being reversely fed, the original to be read next can be carried into the conveyance path 104.
[ 0065 ]
Thereafter, as shown in FIG. 11 (b), the second read sensor 112 detects the trailing edge (backward direction) of the reversely fed document and outputs a detection signal (OFF) (S31). In response to the detection signal, the image reading control unit normally rotates the discharge roller 106 and the retracting roller 113 (S32). As a result, the document that has been fed back to the retreat path 109 is conveyed along the conveyance path 104 toward the paper discharge tray 103.
[ 0066 ]
The second read sensor 112 again detects the leading edge of the conveyed document and outputs a detection signal (ON) (S33), and the image reading control unit receives the detection signal and then a predetermined time has elapsed. As shown in FIG. 12 (after T3 conveyance, S34), the second reading unit 108 starts image reading (S35), and the second read sensor 112 detects the trailing edge of the conveyed document (OFF). ) (S36), the image reading of the second reading unit 108 is terminated (S38) after a predetermined time has elapsed (S37 after T4 conveyance). The document on which the image reading on both sides has been completed is discharged to the discharge tray 103 by the discharge roller 106.
[ 0067 ]
Further, when the next document is present in the paper feed tray 101 (S39), the paper feed clutch is operated (S21), and the same operation as described above is repeated, and the document placed on the paper feed tray 101 is repeated. Documents are sequentially taken out from the bundle, and image reading from the first side to the nth side is performed. Of course, as described above, after the image reading by the first reading unit 107 is completed, the next original can be carried into the conveyance path 104.
[ 0068 ]
As described above, according to the image reading apparatus 100 according to the present embodiment, the distance of the conveyance path 104 between the reading position of the first reading unit and the reading position of the second reading unit, and the first read sensor 111. The distance of the conveyance path between the detection position of the second read sensor 112 and the detection position of the second read sensor 112 is set to an A4 size width (210 mm) or more, so the first reading unit 107 and the second reading in double-sided reading of A4 size or less. There is no duplication of image reading with the unit 108. As a result, the image processing circuit and the like can be shared by the first reading unit 107 and the second reading unit 108, the circuit configuration can be simplified, and the apparatus can be made compact and the cost can be reduced.
[ 0069 ]
An A4 size or smaller document can be read on both sides by one conveyance in one direction. On the other hand, a document larger than an A4 size can be conveyed once in the reverse direction after the first reading unit 107 completes image reading. Thus, the second reading unit 108 can read an image. As a result, the image reading speed of an A4 size or smaller original is increased, and the conveyance distance and the conveyance direction are simplified, so that jamming or the like hardly occurs.
[ 0070 ]
Further, a retreat path 109 is provided in the transport path 104, and when a document larger than A4 size is transported in the reverse direction, the rear end of the document is guided to the retreat path 109 to the reading position of the first reading unit 107. Therefore, the document to be read next can be supplied to the conveyance path 104 in advance. Thereby, the image reading speed is further increased.
[ 0071 ]
Hereinafter, an image reading apparatus 200 according to a modification of the embodiment will be described.
As shown in FIGS. 15 and 16, the image reading apparatus 200 includes a size sensor 114 for detecting the length in the conveyance direction of a document on a conveyance path 104 between the document set sensor 110 and the first lead sensor 111. And a width sensor 115 for detecting the length in the width direction of the document, and other configurations are the same as those of the image reading apparatus 100, and the same reference numerals as those in FIG. .
[ 0072 ]
The size sensor 114 detects the presence or absence of a document conveyed on the conveyance path 104 and outputs a detection signal. The distance of the conveyance path 104 to the first lead sensor 111 is the distance of the document to be normally read. It is arranged at a position slightly longer than the length. On the other hand, the width sensor 115 detects the length in the width direction of the document conveyed on the conveyance path 104. Although not shown in detail in the drawing, for example, a standard width such as A4 size, B4 size, etc. Are arranged in the width direction at the positions.
[ 0073 ]
Also in the image reading apparatus 200, the uppermost sheet of the document placed on the paper feed tray 101 is fed into the conveyance path 104 by the pickup roller 102 a, the separation roller 102 b, and the retard roller 102 c, and the document is loaded by the conveyance roller 105. While being conveyed along the conveyance path 104, the size sensor 114 outputs an ON signal when the leading edge of the original is detected, and outputs an OFF signal when the trailing edge is detected. Of course, on / off may be reversed. The width sensor 115 detects the width of the document.
[ 0074 ]
When the original is further conveyed, the first read sensor 111 detects the leading edge of the original. When the image reading control unit receives the detection signal from the first read sensor 111, the size sensor 114 is turned on. Check the / off signal. As shown in FIG. 17A, when the document is A4 size or smaller, the trailing edge of the document has passed the detection position of the size sensor 114, and the size sensor 114 has already output an OFF signal. . On the other hand, as shown in FIG. 17B, when the document is larger than the A4 size, the trailing edge of the document is upstream of the detection position of the size sensor 114, and the size sensor 114 outputs an ON signal. It remains.
[ 0075 ]
As described above, the image reading control unit converts the image of the document into the first reading unit based on the output signal of the size sensor 114 and the output signal of the width sensor 115 when the first read sensor 111 detects the leading edge of the document. If the size of the document is determined before reading in 107 and the conveyed document is A4 size or smaller, as described above, the operation shown in FIG. The image reading apparatus 200 is controlled to perform the operation shown in FIG.
[ 0076 ]
As a result, even when the bundle of documents placed on the paper feed tray 101 is a mixture of various sizes such as A4 size and B4 size, the document size is read before image reading based on the detection signal of the size sensor 114. If the document is A4 size or smaller, the document is conveyed on the conveyance path 104 as it is and double-sided scanning is performed. If the document is larger than A4 size, the document is temporarily sent back to the retreat path 109. After that, the second reading unit 108 can be read. Therefore, for example, it is possible to appropriately read various sizes of originals and print them at the respective sizes, or to appropriately reduce or enlarge the originals to be printed in the A4 size.
[ 0077 ]
Even when the document size is constant, the image reading control unit automatically determines the document size based on the detection signal of the size sensor 114, so that it is not necessary to input the document size in advance using the operation unit. Operation is simplified.
[ 0078 ]
In this modification, the length in the document transport direction is read by the first read sensor 111 and the size sensor 114. However, after the size sensor 114 reaches the leading edge of the document, a timer is provided in the size sensor 114. It is also possible to detect the time for detecting the edge and output the on / off signal, and compare the detected value with a threshold value for determining whether the size is A4 size or less in advance, thereby determining the size of the document.
[ 0079 ]
In this modification, the length of the document in the conveyance direction is read by the first lead sensor 111 and the size sensor 114. Instead, the first lead sensor 111 and the second lead sensor 112 are used. It is also possible to read the length of the document in the conveyance direction. As described above, the distance of the conveyance path 104 between the first read sensor 111 and the second read sensor 112 is set to the first reading unit 107 in double-sided reading of an A4 size or smaller document by assuming that the document to be normally read is A4 size. In order to prevent image reading between the second reading unit 108 and the second reading unit 108, the distance is set to 210 mm or more. However, when the second lead sensor 112 detects the leading edge of the document, the distance is set to be slightly longer than 210 mm. By confirming the ON / OFF signal of the sensor 111, it is possible to determine whether or not the original is A4 size or smaller by reading the length of the original in the conveyance direction as described above. Thus, the image reading control unit determines the size of the document before reading the image with the second reading unit 108, and the document is A4 size or smaller, that is, the image reading between the first reading unit 107 and the second reading unit 108 is performed. If they do not overlap, the original can be conveyed and read by the second reading unit 108, and if it is larger than A4, it can be controlled to be sent back to the retreat path 109.
[0080]
【The invention's effect】
As described above, according to the image reading apparatus according to the present invention, the conveying unit that conveys the document placed on the sheet feeding tray to the sheet discharge tray via the substantially U-shaped conveying path, and the conveying path are arranged. A first reading unit that reads an image on the first side of the document that is being conveyed downwardly from the paper feed tray, and a conveyance path that is disposed on a conveyance path on the opposite side and the downstream side of the first reading unit. An image reading apparatus comprising: a second reading unit that reads an image on a second surface of a document that has been read; and a conveyance path between a reading position of the first reading unit and a reading position of the second reading unit. After the distance is equal to or longer than the length of the original to be read and the retract path for retracting the original conveyed in the reverse direction branches off from the transport path between the first reading means and the second reading means Curved upward in a substantially U-shape and reached above the second reading means to read the image It is provided so as to communicate with a retraction opening formed in the casing of the apparatus, and is provided at a predetermined distance on the transport path on the upstream side of each of the first reading means and the second reading means with a distance slightly longer than the normal reading size. The length of the document to be read detected by the first detection means and the second detection means in the conveyance direction is less than the distance of the conveyance path between the reading position of the first reading means and the reading position of the second reading means. In this case, after the reading of the first reading means, the document is further conveyed by the conveying means and read by the second reading means, and the length of the document to be read in the conveying direction is controlled. If the distance is longer than the distance, after the reading of the first reading means, the trailing edge of the original is detected by the second detecting means upstream from the reading position of the second reading means, and then the conveying means. The front of the document is in front Control is performed so that the second reading unit reads the second reading unit after the sheet is conveyed in the reverse direction while being retreated in a substantially U shape until it is detected by the second detection unit. Since the control means is provided, it is possible to read documents of all sizes, and those that are less than the length of the document to be normally read can be read in one direction without being fed back and circulated. Image reading on both sides can be performed with a single conveyance.
As a result, the image reading speed is increased and jamming or the like in the conveyance path is less likely to occur. Further, in double-sided reading below the original to be read, image reading by the first reading unit and the second reading unit does not overlap. As a result, a circuit for processing signals read by the first reading unit and the second reading unit can be shared, and the apparatus can be made compact and the cost can be reduced.
Further, after branching from the conveying path between the first reading means and the second reading means, the retraction opening formed in the casing of the image reading apparatus is curved upward in a substantially U shape and reaches the upper side of the second reading means. Since the evacuation path is provided so as to communicate with the document, the document conveyed in the reverse direction is conveyed to the evacuation path, and the rear end of the document does not reach the reading position of the first reading unit, and is read next. The original to be fed can be supplied to the conveyance path. Thereby, the image reading speed is further increased.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of an image reading apparatus 100 according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating control of the image reading apparatus 100.
FIG. 3 is an enlarged view showing a configuration near a branch point of a retreat path 109;
FIG. 4 is a schematic diagram showing a modified example of the retreat path 109;
FIG. 5 is a flowchart showing the operation of the image reading apparatus 100 when reading a document of A4 size or smaller.
FIG. 6 is a flowchart showing the operation of the image reading apparatus 100 when reading a document larger than A4 size.
FIG. 7 is a schematic diagram illustrating a document conveyance state when the image reading apparatus 100 reads a document of A4 size or smaller.
FIG. 8 is a schematic diagram illustrating a document conveyance state when the image reading apparatus 100 reads a document of A4 size or smaller.
FIG. 9 is a schematic diagram illustrating a document conveyance state when the image reading apparatus 100 reads a document of A4 size or smaller.
FIG. 10 is a schematic diagram illustrating a document conveyance state when the image reading apparatus 100 reads a document larger than A4 size.
FIG. 11 is a schematic diagram illustrating a document conveyance state when the image reading apparatus 100 reads a document larger than an A4 size.
12 is a schematic diagram illustrating a document conveyance state when the image reading apparatus 100 reads a document larger than an A4 size. FIG.
FIG. 13A is a schematic diagram showing a reading order when reading a document from the top sheet, and FIG. 13B is a schematic diagram showing a reading order when reading a document from the bottom sheet. It is.
14 is a block diagram showing an example of a circuit configuration until image data read by the first reading unit 107 and the second reading unit 108 is output to the main body control unit. FIG.
FIG. 15 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus 200 according to a modification of the present embodiment.
16 is a block diagram showing control of the image reading apparatus 200. FIG.
17A is a schematic diagram illustrating a document conveyance state when a document of A4 size or smaller is read, and FIG. 17B is a schematic diagram illustrating a document conveyance state when a document larger than A4 size is read. is there.
FIG. 18 is a schematic diagram for explaining the configuration of a conventional sheet-through type image reading apparatus 800.
FIG. 19 is a schematic diagram for explaining the operation of a conventional sheet-through type image reading apparatus 800;
20 is a schematic diagram for explaining the operation of a conventional sheet-through type image reading apparatus 800. FIG.
[Explanation of symbols]
100, 200 image reading apparatus
101 Paper tray
103 Output tray
104 Transport path
105 Conveying roller (conveying means)
107 1st reading unit (1st reading means)
108 Second reading unit (second reading means)
109 Retreat path
111 First lead sensor (first detecting means)
112 Second lead sensor (second detection means)

Claims (6)

A conveying unit that conveys a document placed on the sheet feeding tray to a sheet discharge tray through a substantially U-shaped conveying path, and is disposed on the conveying path and is reversed and conveyed downward from the sheet feeding tray. First reading means for reading an image on the first surface of the document, and second reading for reading an image on the second surface of the document being conveyed, which is arranged on the transport path opposite and downstream of the first reading means. An image reading apparatus comprising:
The distance of the conveyance path between the reading position of the first reading means and the reading position of the second reading means is equal to or longer than the length of the original to be read;
A retraction path for retreating a document conveyed in the reverse direction branches from the conveyance path between the first reading means and the second reading means, and then curves upward in a substantially U shape so that the second reading means Is provided to communicate with a retraction opening formed in the casing of the image reading apparatus.
The first detection means and the second detection means should be read by the first detection means and the second detection means provided at predetermined positions on the upstream-side conveyance path at a distance slightly longer than the normal reading size. When the length of the document in the conveyance direction is equal to or less than the distance of the conveyance path between the reading position of the first reading unit and the reading position of the second reading unit, after the reading of the first reading unit is finished, Control is performed so that the document is further conveyed by the conveying unit and read by the second reading unit. If the length of the document to be read in the conveying direction is longer than the distance, the first reading unit After the end of reading, the trailing edge of the document is detected by the second detection means upstream of the reading position of the second reading means, and then retracted until the leading edge of the document is detected by the second detection means by the conveying means. Retreat to the road in a substantially U shape After transporting in the opposite direction while the image reading apparatus according to the positive direction is conveyed to, characterized in that the control means for controlling so as to read the second reading means is provided again.   The first detection means detects a document being conveyed and outputs a detection signal to control the start and end of image reading of the first reading means, and the second detection means outputs the detection signal. The image reading apparatus according to claim 1, wherein the image reading apparatus detects a document being conveyed and outputs a detection signal in order to control start and end of image reading.   The image reading apparatus according to claim 1, wherein the document to be normally read is an A4 size document.   The image reading apparatus according to claim 1, wherein a distance of the conveyance path between the reading position of the first reading unit and the reading position of the second reading unit is 210 mm or more.   The image reading apparatus according to claim 2, wherein a distance of the conveyance path between the detection position of the first detection unit and the detection position of the second detection unit is 210 mm or more.   6. The image reading apparatus according to claim 1, further comprising an image processing circuit that performs image processing of image data read by the first reading unit and the second reading unit. .

Images