JP5663961B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that reads an image of a document, and more specifically, a first image reading unit that reads one side of a document that is transported along a transport path, and the document that is transported along the transport path. The present invention relates to an image reading apparatus including a second image reading unit that reads the other surface of the image reading unit.

  2. Description of the Related Art Conventionally, an image reading device that reads an image of a document is applied to devices such as a scanner, a copying machine, and a facsimile machine. As a configuration for reading images on both sides of a document with this type of image reading apparatus, a configuration has been proposed in which a single image reading unit reads images on both the front and back sides by reversing the document by devising the conveyance path of the document. In recent years, however, a configuration has been proposed in which two image reading units simultaneously read both front and back images. For example, a first image reading unit that reads one side of a document that is conveyed along a conveyance path and a second image reading unit that reads the other side of the document that is conveyed along the conveyance path are provided. In the image reading apparatus, the image reading operation on the one surface by the first image reading unit and the image reading operation on the other surface by the second image reading unit can be executed in parallel, thereby improving the reading speed. be able to.

  Further, in this type of image reading apparatus, the first image reading unit and the second image reading unit are connected to a common line buffer group via a switch, and the switch is used to alternately read the read signal output from each image reading unit. It has been proposed to store in the line buffer group by switching to (for example, see Patent Document 1).

  On the other hand, in an image reading apparatus having a plurality of light receiving elements arranged in the main scanning direction and including an image reading unit that sequentially outputs a read signal of each light receiving element, a light receiving element disposed in a so-called dummy pixel region is used. It is known that the read signal is unnecessary. Therefore, in an image reading apparatus that includes one image reading unit and reads an image on one side of a document, the transfer clock of the read signal corresponding to the dummy pixel area is made faster than the transfer clock of the read signal corresponding to the effective area. This has also been proposed (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 9-200347 JP 2004-172854 A

  However, when the reading signal from the first image reading unit and the reading signal from the second image reading unit are alternately switched and stored in a common line buffer group as in Patent Document 1, the reading from each image reading unit is performed. The reading time is longer than when the signals are individually stored in separate line buffer groups. That is, in this case, sharing the line buffer group is advantageous in terms of cost but disadvantageous in reading time. If the technique of Patent Document 2 is combined with the technique of Patent Document 1, the reading speed is somewhat improved, but this is not sufficient.

  Accordingly, the present invention provides a first image reading unit that reads one side of a document that is conveyed along a conveyance path, and a second image reading unit that reads the other side of the document that is conveyed along the conveyance path. In the image reading apparatus having the above, the reading signal from each image reading unit can be processed by one processing unit while ensuring the reading speed.

The image reading apparatus of the present invention made to achieve the above object has a plurality of first light receiving elements arranged in the main scanning direction, and one surface of the document conveyed in the sub-scanning direction along the conveying path. A first image reading unit that sequentially reads the image of the first light receiving element and sequentially outputs a read signal of the first light receiving element, and a plurality of second light receiving elements arranged in the main scanning direction. Second image reading for reading an image on the other side of the document conveyed in the sub-scanning direction along the conveyance path through each second light receiving element and sequentially outputting a read signal of each second light receiving element A control unit that controls the output timing of the read signal by the first image reading unit and the second image reading unit, and a document width detection unit that detects the width of the document in the main scanning direction, wherein, depending on the prior SL width document width detection unit detects Set the output timing of the read signal by the first image reading unit and the output timing of the read signal by the second image reading unit, and correspond to the width of the read signal output by the first image reading unit The output of the read signal by the second image reading unit is started before the output of the read signal related to the read region is completed, thereby corresponding to the width of the read signal output by the first image reading unit. When output of the read signal related to the read area is completed, output of the read signal related to the read area corresponding to the width of the read signal output from the second image reading unit is started. It is characterized by.

  In the present invention configured as described above, the first image reading unit includes a plurality of first light receiving elements arranged in the main scanning direction, and one of the documents conveyed in the sub-scanning direction along the conveyance path. The image of the surface is read through the first light receiving elements, and the read signals of the first light receiving elements are sequentially output. Similarly, the second image reading unit includes a plurality of second light receiving elements arranged in the main scanning direction, and images the other surface of the document conveyed in the sub scanning direction along the conveyance path. Reading is performed via the second light receiving elements, and read signals of the respective second light receiving elements are sequentially output.

The document width detection unit detects the width of the document in the main scanning direction. Then, the read signal from the light receiving element disposed in the area deviated from the width of the document detected by the document width detecting unit is unnecessary as the read signal from the light receiving element disposed in the dummy pixel area described above. It can be seen that this is a read signal. Therefore, the image reading control section provided in the apparatus of the present invention, by pre-Symbol the second image reading unit and the output timing of the read signal by the first image reading unit according to the document width width detecting section detects The output timing of the reading signal is set, and the second image reading unit outputs the reading signal related to the reading area corresponding to the width among the reading signals output by the first image reading unit. When the output of the reading signal is started, the second image reading unit is output when the output of the reading signal related to the reading region corresponding to the width of the reading signal output by the first image reading unit is completed. Among the read signals output by the, the output of the read signal related to the read area corresponding to the width is started . For this reason, the time during which an unnecessary read signal is output is reduced, and the reading speed can be improved satisfactorily. Moreover, since the first image reading unit outputs a read signal according to the reading area of the second image reading unit before SL is corresponding to the width from the output of a read signal according to the reading area corresponding to the width, each It is also possible to process the read signal from the image reading unit with one processing unit.

  The control unit outputs a selection signal for selecting one of the first image reading unit or the second image reading unit, and the reading signal output from the first image reading unit or the second image reading unit. And a switching unit that switches between input of a read signal from the first image reading unit or a read signal from the second image reading unit to the processing unit in accordance with the selection signal; May be further provided.

  In this case, according to the selection signal output from the control unit, the switching unit switches whether the reading signal from the first image reading unit or the reading signal from the second image reading unit is input to the processing unit. The processing unit executes processing on the read signal input through the switching unit. In this way, by controlling which of the image reading units the reading signal is input to the processing unit by switching by the switching unit, the reading signal from each image reading unit can be processed smoothly by one processing unit. it can. Note that the processing unit may perform relatively simple processing such as transferring the read signal to another medium or simply performing A / D conversion, and performs relatively advanced processing such as image processing. You may do it.

  In addition, a range in the main scanning direction in which the first light receiving elements are arranged and a range in the main scanning direction in which the second light receiving elements are arranged may be different from each other. In this case, the present invention is as follows. The effect is more prominent. That is, when the range in the main scanning direction in which the first light receiving elements are arranged and the range in the main scanning direction in which the second light receiving elements are arranged are different from each other, both sides of the document conveyed along the conveyance path are arranged. When reading, the number of light receiving elements arranged in a region outside the width of the original increases. In the present invention, as described above, the time required for outputting the read signal from such a light receiving element can be reduced, and thereby the reading speed can be further remarkably improved.

1 is a perspective view schematically illustrating a configuration of a multifunction machine to which the present invention is applied. FIG. 2 is a cross-sectional view schematically illustrating a configuration of a main part of an image reading apparatus mounted on the multifunction machine. FIG. 3 is a perspective view illustrating a configuration in the vicinity of a first reading device in the image reading apparatus. It is a schematic diagram showing the structure of each reading device of the image reading apparatus. It is a block diagram showing the structure of the control system of the image reading apparatus. It is a flowchart showing the process performed with the control system. It is a time chart which illustrates the effect of the processing. It is a time chart which illustrates the effect of the modification of the above-mentioned image reading device. It is a flowchart showing the modification of the said process.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view schematically showing the configuration of a multifunction machine 1 to which the present invention is applied. FIG. 2 is a schematic diagram showing the configuration of the main part of an image reading apparatus 10 mounted on the multifunction machine 1. It is sectional drawing to represent. As shown in FIG. 1, the multifunction machine 1 includes a document cover 30 that can be opened and closed on the upper surface of the base body 20.

[Entire configuration of image reading apparatus]
As shown in FIG. 1, a glass platen 21 on which an original (not shown) is placed on the upper end surface of the base 20 when the image reading apparatus 10 of the present embodiment is used as a flatbed scanner. Is provided. Then, the document cover 30 is closed on the surface of the document table 21 to cover the document placed on the document table 21, so that one side of the upper end surface of the base body 20 (the back side in FIG. The side of the side is also referred to as the rear side), and is attached to the end edge via a hinge 31 so as to be opened and closed.

  Further, as shown in FIG. 2, the document cover 30 is configured as a document cover having an ADF (Automatic Document Feeder), and conveys the document placed on the sheet feeding tray 110 in the sub-scanning direction along the conveyance path. In addition, a transport unit 100 that functions as an ADF and a first reading device 210 (an example of a first image reading unit) capable of reading an image on the back side of a document transported along a transport path are provided. Note that a second reading device 230 (an example of a second image reading unit) capable of reading an image on the surface of a document in parallel with the first reading device 210 is provided on the base 20.

  The transport unit 100 includes transport rollers 121 to 129 that transport the document placed on the paper feed tray 110 to the paper discharge tray 130 along the transport path (dotted line in FIG. 2). Of these transport rollers 121 to 129, the most upstream transport rollers 121 and 122 are held by a holder 133.

  In addition, an upstream side reading position and a downstream side reading position are set in this conveyance path, and the first reading device 210 for reading an image on the back side (corresponding to one side) of the document is the upstream side reading. Further, a back side document presser 220 is provided that presses a document passing through the upstream reading position against the reading surface of the first reading device 210. A second reading device 230 provided on the document table 21 for reading an image on the surface of the document (corresponding to the other surface) is configured to be movable to a position corresponding to the downstream reading position. A front-side document holder 240 that presses a document passing through the downstream reading position against the reading surface of the second reading device 230 is provided.

  Further, an F sensor 310, an RB sensor 320, and an R sensor 330 are provided as document sensors for detecting the presence or absence of a document being conveyed at a corresponding position on the conveyance path. The second reading device 230 is fixed to an endless belt 357 provided between a driving pulley 353 that is rotationally driven by a motor 351 and a driven pulley (not shown), and the document table is rotated according to the rotation of the motor 351. 21 can be moved in the sub-scanning direction (left-right direction).

  Further, as shown in FIG. 3 in which a part of the document cover 30 is opened, the width L in the main scanning direction of the first reading device 210 is designed to be smaller than the width D of the document that can be transported by the transport unit 100. ing. The width in the main scanning direction of the second reading device 230 is designed to be slightly larger than the width D. This is because the conveyance unit 100 can convey up to A3 size originals, and the width D matches the short side of the A3 size. This is because the first reading device 210 can read up to A4 size vertically placed originals. That is, the width L is designed to be slightly longer than the short side of the A4 size in consideration of a dummy pixel region described later, and single-sided reading using only the second reading device 230 for an A3 size document. Is only feasible.

FIG. 4A is a schematic diagram illustrating the configuration of the second reading device 230, and FIG. 4B is a schematic diagram illustrating the configuration of the first reading device 210.
As shown in FIG. 4A, the second reading device 230 includes a plurality of lenses 234 arranged in the main scanning direction over a range slightly longer than the short side of the A3 size (A3 document size). A plurality of light receiving elements 235 (an example of second light receiving elements) are provided at the imaging positions of the lenses 234, respectively. The electric charge accumulated according to the amount of light received by each light receiving element 235 via the lens 234 is sequentially output for each light receiving element 235 at a timing according to a trigger signal TGB (see FIG. 5) described later, and an output device comprising an amplifier. 236 is amplified. The light receiving elements 235 near both ends in the main scanning direction are light receiving elements 235 in a so-called dummy pixel area where an appropriate output cannot be obtained, and the light receiving elements 235 disposed inside the area have a short side of A3 size. It is arranged over the length.

  As shown in FIG. 4B, the first reading device 210 includes a plurality of lenses 214 arranged in the main scanning direction over a slightly longer range than the short side of A4 size (A4 document size). A plurality of light receiving elements 215 (an example of first light receiving elements) are provided at the imaging positions of the lenses 214. The charges accumulated in each light receiving element 215 according to the amount of received light are sequentially output for each light receiving element 215 at a timing according to a trigger signal TGA (see FIG. 5) described later and amplified by the output unit 216. Further, as shown in FIGS. 4A and 4B, the second reading device 230 and the first reading device 210 are arranged so that the centers in the main scanning direction coincide with each other.

[Configuration of control system of image reading apparatus]
Next, FIG. 5 is a block diagram illustrating a configuration of a control system of the image reading apparatus 10. As shown in FIG. 5, this control system is configured around an ASIC 400 (an example of a control unit), and the ASIC 400 includes a first reading device 210 (ADF side CIS) and a second reading device 230 (FB side CIS). A timing generation circuit 401 that outputs the above-described trigger signals TGA and TGB is provided. Note that the timing generation circuit 401 also outputs clock signals CLKA and CLKB to the first reading device 210 and the second reading device 230, respectively, and also outputs the following selection signal SEL.

  That is, the outputs (read signals) from the aforementioned output devices 216 and 236 are output from the first reading device 210 and the second reading device 230 as analog outputs A and B (AnalogOUTPUTA, B). In an A / D conversion circuit 410 as an example of a processing unit that converts these analog outputs A and B into digital signals, one of the analog outputs A and B includes a switch circuit 420 (an example of a switching unit). Is input via. The switch circuit 420 switches which analog output A or B is input to the A / D conversion circuit 410 based on the selection signal SEL input from the timing generation circuit 401.

  Further, the ASIC 400 includes a CPU 402, a ROM 403, a RAM 404, and an image processing unit 406, which are connected to the timing generation circuit 401 via the bus 409. The output converted into a digital signal by the A / D conversion circuit 410 is temporarily stored as data in the RAM 404 and then subjected to various image processing by the image processing unit 406. Although not shown in FIG. 5, the ASIC 400 includes an operation panel 600 (see FIG. 1) provided on the housing surface of the multifunction device 1, a motor (not shown) for driving the transport unit 100, Various sensors 310 to 330 (see FIG. 2) are also connected. Note that the operation panel 600 has an input unit such as a switch and a display unit.

[Processing in the above control system]
Next, FIG. 6 is a flowchart showing processing executed by the CPU 402 of the ASIC 400 based on a program stored in the ROM 403. This process is started when a document is placed on the paper feed tray 110 and reading of the document is instructed via the operation panel 600.

  As shown in FIG. 6, in this process, first, in S101 (S represents a step: the same applies hereinafter), the transport unit 100 is driven to start transporting a document. Then, in subsequent S102, based on the signals from the various sensors 310 to 330, it is determined whether or not the document has been conveyed to the image reading position (back surface position) by the first reading device 210. If the document is not transported to the back surface position (S102: N), the process stands by in S102, and if the document is transported to the back surface position (S102: Y), the process proceeds to S103. In S103, when the selection signal SEL is controlled to L level, the switch circuit 420 is switched to the analog output A side, and the first reading device 210 performs the reading operation of the back side of the document. In S104 as an example of the subsequent document width detection unit, processing for detecting the document size is executed based on the reading result.

  In the subsequent S105, it is determined whether or not the document size has been detected by the process of S104. If it can be detected (S105: Y), the output timings of the trigger signals TGA and TGB at the time of double-sided reading (S108) to be described later. If the document size cannot be detected after the calculation in S106 (S105: N), the process proceeds to S107. In S107, based on the signals from the various sensors 310 to 330, it is determined whether or not the document has been conveyed to the image reading position (front surface position) by the second reading device 230. If the document has not been transported to the front surface position (S107: N), the process proceeds to S103 described above, the back side scanning is continued, and if the document is transported to the front surface position (S107: Y), the process proceeds to S108. Migrate to In S108, the reading operation of both the front and back sides of the document by the first reading device 210 and the second reading device 230 is executed as follows based on the calculation result in S106.

  That is, the output timing of the trigger signals TGA and TGB is set as shown in FIG. That is, the analog output A is output according to the trigger signal TGA, the trigger signal TGB is output after the output ends, and the analog output B is output. On the other hand, for example, if it is determined in S106 that the document size is A4 portrait (that is, the width in the main scanning direction is the short side of the A4 size), the output timing of the trigger signals TGA and TGB is as shown in FIG. ). That is, when the output of the reading area corresponding to the A4 size short side of the analog output A output in response to the trigger signal TGA is completed, the reading area corresponding to the A4 size short side of the analog output B is finished. The output timing of the trigger signal TGB is controlled so that the output is started. The selection signal SEL is controlled to H level only during the output of the reading area of the analog output B, and the analog output B of the reading area is switched via the switch circuit 420 to the A / D conversion circuit 410. Is input.

  In addition, when a negative determination is always made in S105 during the back side reading by the processing of S103 to S107 and the calculation in S106 is not performed, the trigger signals TGA and TGB are output at the initial setting timing shown in FIG. Is done.

  Returning to FIG. 6, in S <b> 108, such double-sided reading is executed, and in subsequent S <b> 109, based on the signals from the various sensors 310 to 330, whether or not the trailing edge of the document has passed the aforementioned back surface position is determined. To be judged. If the document has not passed the back surface position (S109: N), the process proceeds to S108, duplex scanning is continued, and if the document passes the back surface position (S109: Y), the process proceeds to S110. In S110, when the selection signal SEL is controlled to H level, the switch circuit 420 is switched to the analog output B side, and the reading operation of the surface of the document by the second reading device 230 is executed. In subsequent S111, it is determined whether or not the document discharge is completed based on signals from the various sensors 310 to 330. If the document discharge has not been completed (S111: N), the process proceeds to S110, the front side reading is continued, and when the document discharge is completed (S111: Y), the process is temporarily terminated. .

[Effect of this embodiment and its modification]
As described above, the ASIC 400 sets the output timing of the trigger signals TGA and TGB as illustrated in FIG. 7A, for example, so that the output of the reading area corresponding to the short side of A4 size in the analog output A can be obtained. At the time of completion, output of the reading area corresponding to the short side of A4 size in the analog output B is started. For this reason, the time during which an unnecessary read signal is output is reduced, and the reading speed can be improved satisfactorily. That is, in the conventional double-sided reading, as shown in FIG. 7B, the reading time becomes long, but in this embodiment, the reading time can be shortened favorably.

  Further, in the present embodiment, the analog output B is output in the reading area after the output of the analog output A in the reading area is completed, so that each analog output A, B can be processed satisfactorily. Furthermore, in the present embodiment, the main scanning direction range in which the light receiving elements 215 of the first reading device 210 are arranged is different from the main scanning direction range in which the light receiving elements 235 of the second reading device 230 are arranged. Yes. For this reason, when both sides of the document are read, the number of light receiving elements 235 disposed in a region outside the width of the document increases. In this embodiment, the output of a read signal from such a light receiving element 235 is provided. Therefore, the reading speed can be significantly improved.

  In addition, this invention is not limited to the said embodiment at all, It can implement with a various form in the range which does not deviate from the summary of this invention. For example, in the above embodiment, the second reading device 230 and the first reading device 210 are arranged so that the centers in the main scanning direction coincide with each other, but the second reading device 230 and the first reading device 210 are different from each other. You may arrange | position so that the end of the main scanning direction may correspond. Also in this case, the same processing as in the above embodiment can be applied.

  Further, both the second reading device 230 and the first reading device 210 may correspond to the A3 document size. In this case, the output timings of the trigger signals TGA and TGB are set as follows.

  That is, when double-sided scanning of an A3 size document is executed, as illustrated in FIG. 8A, when the output of the reading area corresponding to the short side of A3 size in the analog output A is completed, The timing is set so that the output of the reading area corresponding to the short side of the A3 size of the analog output B is started and the output of the reading area of the analog output A is started when the output of the reading area is finished. Is done. When double-sided scanning of an A4 size document is executed, the analog output is completed when the output of the reading area corresponding to the short side of A4 size is completed in the analog output A output in response to the trigger signal TGA. The output timing of the trigger signal TGB is set so that the output of the reading area corresponding to the A4 size short side of B is started. In these cases, the reading time can be shortened satisfactorily as in the above embodiment.

  In the above embodiment, the document size is detected when reading the back side (S104). However, the document size may be detected based on an input from the operation panel 600 (an example of a document width detection unit). FIG. 9 is a flowchart showing such a form of processing. As shown in FIG. 9, in this process, first, in S201, the document size is detected based on the input from the operation panel 600, and in the subsequent S202, the output timings of the trigger signals TGA and TGB are the same as in S106. Calculated. In the subsequent S203, the document is read based on the timing calculated in S202, and the process ends. Note that the process of S203 is the same as the process in which the processes of S103 to S106 are deleted in the flowchart of FIG. Also in this case, the reading time can be shortened satisfactorily as in the above embodiment.

DESCRIPTION OF SYMBOLS 1 ... MFP 10 ... Image reading device 21 ... Document stand 30 ... Document cover 100 ... Conveying section 210 ... First reading device 215, 235 ... Light receiving element 230 ... Second reading device 310 ... F sensor 320 ... RB sensor 330 ... R Sensor 351 ... Motor 400 ... ASIC 401 ... Timing generation circuit 410 ... A / D conversion circuit 420 ... Switch circuit 600 ... Operation panel

Claims (3)

It has a plurality of first light receiving elements arranged in the main scanning direction, reads an image of one side of the document conveyed in the sub scanning direction along the conveyance path through each first light receiving element, and A first image reading unit that sequentially outputs a reading signal of the first light receiving element;
It has a plurality of second light receiving elements arranged in the main scanning direction, reads the image of the other side of the document conveyed in the sub scanning direction along the conveying path through each second light receiving element, and A second image reading unit that sequentially outputs a reading signal of each second light receiving element;
A control unit for controlling the output timing of the read signal by the first image reading unit and the second image reading unit;
A document width detector for detecting a width of the document in the main scanning direction;
With
Wherein the control unit sets an output timing before Symbol the read signal by the second image reading unit and the output timing of the read signal by the first image reading unit according to the width of the document width detecting unit detects, By starting the output of the reading signal by the second image reading unit before the output of the reading signal related to the reading region corresponding to the width among the reading signals output by the first image reading unit is completed, When the output of the read signal related to the read area corresponding to the width of the read signal output by the first image reading unit is completed, the width of the read signal output by the second image reading unit is set to the width. An image reading apparatus , wherein output of a reading signal related to a corresponding reading area is started . The control unit outputs a selection signal for selecting one of the first image reading unit or the second image reading unit,
A processing unit for processing a read signal output from the first image reading unit or the second image reading unit;
A switching unit for switching whether to input a reading signal from the first image reading unit or a reading signal from the second image reading unit to the processing unit in accordance with the selection signal;
The image reading apparatus according to claim 1, further comprising:   3. The image reading according to claim 1, wherein a range in the main scanning direction in which the first light receiving elements are arranged and a range in the main scanning direction in which the second light receiving elements are arranged are different from each other. apparatus.

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