JP2010273099A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader reducing the amount of power consumption. <P>SOLUTION: In groups G1-G6 including a plurality of LEDs, only the groups G3, G4, G6 are turned on successively and the other groups are kept off in the detection of a document size. If the document size is detected at a point in time when, for example, the group G4 is turned on, document size detection operation is completed without turning on the group G6, thus reducing the amount of power consumption in the detection of the document size. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that reads an image on a document.

  Conventionally, a mechanism for detecting the size of a document in an image reading apparatus has been proposed. For example, Patent Document 1 describes a plurality of document detection sensors arranged in the main scanning direction and the sub-scanning direction.

JP 2007-28413 A

  In order to reduce the number of types of members, instead of providing a document detection sensor as in the prior art, for example, a light source used as illumination when reading an image from a document may be used for document detection. However, in recent years, there are cases where a plurality of light sources arranged in the main scanning direction are provided as illumination light sources, and turning on all of the plurality of light sources when detecting the document size wastes power. It will be. In addition, the user may feel uncomfortable due to glare.

  Accordingly, an object of the present invention is to provide an image reading apparatus capable of reducing power consumption.

  The first image reading apparatus includes a document placing table on which a document is placed, a plurality of light sources arranged in the main scanning direction, a light source driving unit that drives the light source, and two light sources when detecting the document size. A light source control unit that controls the light source driving unit to drive in the above groups, turns on the light source at different timing for each group, and terminates the lighting of the document when a document size is detected; Detecting a position of an edge of the document from a reading element disposed at a position for receiving light emitted from the light source and reflected by the document on the document table and an output signal from the reading element; A size detection unit that detects a document size; and a reading control unit that controls the light source driving unit to turn on the light source and illuminate the document when reading an image.

  The second image reading apparatus is the first image reading apparatus, and the light source control unit keeps the light sources of some of the groups turned off when the document size is detected.

  The third image reading device is the first or second image reading device, and the light source control unit can turn on two or more light sources of the groups when detecting the document size, A light source illuminates the placement positions of two or more standard originals having different sizes on the original placement table.

  The fourth image reading device is any one of the first to third image reading devices, and the light source control unit can turn on two or more light sources of the group when detecting the document size. In the document placing table, the light source is turned on so that regions illuminated by different groups of light sources straddle the position of the edge of the standard document on the document placing table.

  The fifth image reading device is any one of the first to third image reading devices, and the light source control unit is an area illuminated by the light source on the document placing table when the document size is detected. However, the original is turned on so as to be arranged between the edges of the standard originals having different sizes on the original placement table.

  According to a sixth image forming apparatus, on the recording medium, the image reading apparatus according to any one of the first to fifth inventions and image data obtained by the image reading apparatus reading an image on a document. And an image forming unit for forming an image.

  In the first image reading apparatus, the document size can be detected without turning on all the light sources. Therefore, this image reading apparatus can reduce power consumption.

1 is a perspective view of an image reading apparatus 1 according to a first embodiment. 1 is a diagram schematically showing an internal configuration of an image reading apparatus 1; The top view of the light source part 21b. FIG. 2 is a block diagram illustrating a main configuration of the image reading apparatus 1. 3 is a flowchart showing a flow of operations when detecting a document size in the image reading apparatus 1; 3 is a view showing the position of the first carriage 21a with respect to the platen glass 11. FIG. The figure which shows the mode of lighting / extinction of the light source part 21b at the time of document size detection. The figure which shows the mode of lighting / extinguishing of the light source part 21b at the time of document size detection in 2nd Embodiment. The figure which shows the mode of lighting / extinguishing of the light source part 21b at the time of the document size detection in 3rd Embodiment. The figure which shows the mode of lighting / extinguishing of the light source part 21b at the time of document size detection in 4th Embodiment. 1 is a block diagram showing an outline of an image forming apparatus incorporating an image reading apparatus.

  The following embodiments do not limit the present invention.

[1] First Embodiment (1-1) Schematic Configuration of Image Reading Apparatus 1 As shown in FIG. 1, the image reading apparatus 1 includes a casing 10, a platen glass (an example of a document table) 11, and a document cover 12. Prepare.

  The platen glass 11 is provided on the upper surface of the housing 10. The platen glass 11 is a plate-like member made of a transparent material such as glass.

  The document cover 12 is fixed to one edge of the upper surface of the housing 10 via a hinge. The document cover 12 opens and closes with respect to the platen glass 11 by rotating via a hinge.

  As shown in FIG. 2, a reading unit 2 is provided in the housing 10. The reading unit 2 includes an illumination unit 21, an optical unit 22, a lens 23, and a reading element 24.

  The illumination unit 21 includes a first carriage 21a, a light source unit 21b, a mirror, and the like. The first carriage 21a is provided so as to be movable in the sub-scanning direction. The light source unit 21b is provided in the first carriage 21a.

  As shown in FIG. 3, the light source unit 21 b includes a base material 27 and LEDs 28.

  The base material 27 is a plate-like member extending in the main scanning direction. The length of the base material 27 in the main scanning direction is longer than the width of the maximum size of the document that can be read by the image reading apparatus 1 in the main scanning direction. For example, in the present embodiment, the maximum document size is A3, and as shown in FIG. 7, the maximum document width in the main scanning direction is the width in the short direction of A3 (the width in the longitudinal direction of A4). It is. Therefore, the length of the base material 27 in the main scanning direction is set to be slightly longer than the width (297 mm) of A4 in the longitudinal direction, for example, about 350 mm.

  Further, the width in the short direction of the base material 27 is not particularly limited, but is set to about 15 mm, for example.

  The base material 27 has attachment holes 28 in the vicinity of both ends in the longitudinal direction, and is fixed to the substrate by screws through the attachment holes 28. The illustration of both the screw and the substrate is omitted.

  The LED 28 is an example of a light source and has a rectangular shape of about 1 mm × 2 mm. In the light source unit 21 b, a plurality of LEDs 28 are arranged on the base material 27 in the main scanning direction. As will be described later, the LEDs 28 are divided into n (n is a natural number of 2 or more) groups G1 to Gn, and are turned on and off for each group.

  As shown in FIG. 2, the optical unit 22 includes a second carriage 22a and a mirror provided in the second carriage 22a. The carriage 22a is also provided so as to be movable in the sub-scanning direction.

  The lens 23 is disposed on the optical path from the optical unit 22 to the reading element 24.

  The reading element 24 converts light into an electrical signal. As the reading element 24, a known element such as a CCD or a CMOS is preferably used.

  As shown in FIG. 4, the reading unit 2 includes a light source driving unit 210 and a carriage moving unit 211 in addition to the configuration described above.

  The light source driving unit 210 turns on the LED 28 of the illumination unit 21. As shown in FIG. 3, the light source driving unit 210 can drive the LEDs 28 for each of the groups G1, G2,... Gn. n is changed according to the type of document size to be detected. In the present embodiment, n = 6, and the groups G1 to G6 each include a plurality of LEDs 28.

  The carriage moving unit 211 moves the first carriage 21a and the second carriage 22a in the sub-scanning direction. Specifically, the carriage moving unit 211 includes members such as a motor and a gear, and moves the carriages 21a and 22a along a rail (not shown) extending in the sub-scanning direction.

  As shown in FIG. 4, the image reading apparatus 1 includes an image processing unit 42, an open / close sensor 43, and a control device 50 in addition to the configuration described above.

  The image processing unit 42 includes an A / D converter, a shading correction circuit, and the like.

  The open / close sensor 43 is connected to a button 431 (FIG. 1) protruding from the upper surface of the housing 10, and when the downward movement amount of the button 431 exceeds the first predetermined value, the document cover 12 has started to close. Is output to the control device 50.

  The document sensor 44 is an optical sensor unit having a light source and a light receiving unit. The document sensor 44 is disposed under the platen glass 11, that is, in the housing 10 at a position where the document size in the sub-scanning direction can be detected.

As shown in FIG. 7, a document instruction plate 30 is installed outside the platen glass 11 in the sub-scanning direction. The document instruction plate 30 is a plate member with a scale indicating the placement position of the document. According to the scale of the document instruction plate 30, the document is placed so that one corner of the document matches the upper left corner of the platen glass 11 in FIG. The upper left corner of the platen glass 11 is referred to as the “origin” and is given the reference numeral “11a”. In this embodiment, the A6, A5, and A4 size documents are arranged so that the sides in the longitudinal direction are along the main scanning direction. A3 size originals are arranged so that the sides in the short direction are along the main scanning direction. That is, the A3 and A4 size documents have the same length in the main scanning direction.

  Therefore, as shown in FIG. 7, the document sensor 44 is arranged between the right end of the A4 size document on the platen glass 11 and the right end of the A3 size document as viewed from the user.

  The control device 50 includes a size detection execution unit 51 and a reading control unit 55. The control device 50 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and other memories. The function of the control device 50 is realized by the CPU reading and executing a program stored in the ROM or the like.

  The size detection execution unit 51 includes a carriage control unit 52, a light source control unit 53, and a size detection unit 54.

(1-2) Operation when Detecting Document Size During standby, as shown in FIG. 6, the first carriage 21a is positioned at the standby position P1.

  As shown in FIG. 5, when a signal indicating that the document cover 12 has started to close is received from the open / close sensor 43 (Yes in step S51), the carriage moving unit 211 controls the first under the control of the carriage control unit 52. The carriage 21a is moved in the sub scanning direction. As a result, the first carriage 21a is disposed at the size detection position P2 (FIG. 6) (step S52). At this time, under the control of the carriage control unit 52, the second carriage 22a uses the carriage moving unit 211 to convert the light from the first carriage 21a existing at the size detection position P2 (reflected light from the document D) to the second. The mirror in the carriage 22 a is disposed at a position where it can be guided to the lens 23.

  The light source control unit 53 controls lighting of the groups G3, G4, and G6 among the groups G1 to G6 of the LEDs 28 as the first group F1, the second group F2, and the third group F3, respectively.

  As shown in FIG. 7, below the platen glass 11, the group G3 (first group F1) has the A5 size so that the group G4 (second group F2) straddles the edge of the A6 size document in the main scanning direction. The group G6 (third group F3) is positioned so as to straddle the edge of the A4-size document so as to straddle the edge of the document.

  As shown in FIG. 5, under the control of the light source controller 53, the light source driver 210 first turns on the LEDs 28 of the first group F1 arranged closest to the origin 11a (steps S53 → S54).

  The size detection unit 54 analyzes the image data read by the reading element 24 in this state (step S55). When the size detection unit 54 determines from the image data that the edge of the document exists at the position illuminated by the first group F1 (Yes in step S56), the document size is determined to be A6 as shown in Table 1. (Step S57). The LED 28 other than the first group F1 is not lit, and the size detection operation ends.

  On the other hand, if the first group F1 is turned on and no document is detected (No in step S56), the light source control unit 53 turns on the LED 28 of the second group F2 next to the origin 11a next to the first group F1. The LEDs 28 of the first group F1 are turned off (Yes in step S58 → S59 → S54). The size detector 54 tries to detect the size of the document in the same manner as when the first group F1 is lit (step S55). If the edge of the document exists at the position illuminated by the second group F2 (Yes in step S56), the size detection unit 54 determines the document size as A5 as shown in Table 1 (step S57).

  If the edge of the document is not detected even when the second group F2 is turned on (No in step S56), the light source control unit 53 turns on the LED 28 of the third group F3 next to the origin 11a next to the second group F2, The LEDs 28 of the second group F2 are turned off (Yes in step S58 → S59 → S54). The size detector 54 tries to detect the size of the document in the same manner as when the first group F1 is lit (step S55). If there is a document edge at the position illuminated by the third group F3 (Yes in step S56) and the document sensor 44 detects that there is no document, the size detection unit 54 determines the document size as A4, If the document sensor 44 detects that there is a document, the document size is determined as A3 (step S57, Table 1).

  If the document is not detected even when the third group F3 is turned on, that is, if any of the first group F1 to the third group F3 is turned on, if the image data is black as described later, the size is It is determined to be less than A6 (Table 1).

  More details are as follows. When the LED 28 is turned on while the document D is placed on the platen glass 11, the light reflected by the document D out of the light from the light source unit 21 b is further reflected by the mirror of the illumination unit 21 and the mirror of the optical unit 22. Reflected and guided to the lens 23. The reading element 24 detects light passing through the lens 23 and outputs an electrical signal to the image processing unit 42. Image data obtained by processing the electrical signal by the image processing unit 42 is output to the control device 50. Light that has not been reflected by the document D, that is, light from the LED 28 disposed at a position where the document D does not exist, is not detected by the reading element 24. As a result, the area outside the document is a black area on the image data.

  Table 1 shows the correspondence between the image data and the size detection result.

  In Table 1, “G3”, “G4”, and “G6” correspond to image data of regions illuminated on the platen glass 11 by the respective groups G3, G4, and G6.

  When the light amount (that is, the brightness of the image) is greater than or equal to a predetermined value, the size detection unit 54 recognizes the image data of the pixel as “white” (that is, the region where the document exists), and the light amount is less than the predetermined value It may be recognized as “black” (that is, an area where no document exists). The size detection unit 54 recognizes the brighter data as “white” and the darker data as “black” when the difference in signal magnitude between pixels is a certain value or more. It may be.

  A portion where the image data changes from “white” to “black” from the origin 11a toward the main scanning is recognized as the edge of the document. Then, the document size is determined from the position of the edge.

  As described above, the image reading apparatus 1 performs the size determination by turning on some of the LEDs 28 of the light source unit 21b. When the size determination is completed, the size detection is terminated at that time, and therefore, all the LEDs 28 are detected. The size can be detected without lighting up. Therefore, power consumption is reduced. Further, glare can be reduced.

(1-3) Operation at the time of image reading When reading the image of the document D on the platen glass 11, the image reading device 1 operates as follows.

  Under the control of the reading control unit 55, the carriage moving unit 211 moves the illumination unit 21 and the optical unit 22 in the sub-scanning direction so as to illuminate the entire surface of the document D. At this time, the reading control unit 55 adjusts the movement range of the illumination unit 21 and the optical unit 22 in the sub-scanning direction based on the document size detected by the size detection unit 54 described above. That is, if the document size is A5, the illumination unit 21 and the optical unit 22 are moved so as to illuminate from the left end to the right end of the A5 size document in FIG. Since it is not necessary to illuminate the right side of the right end of the A5 size document, the illumination unit 21 is returned to the standby position P1 when it is moved from the standby position P1 to the right end of the A5 size document.

  Further, the range of the LED 28 that is turned on at the time of image reading may be adjusted by the reading control unit 55 based on the document size detected by the size detecting unit 54. In this case, if the document size is A5, the LEDs 28 of the groups G1 to G4 are turned on, and the LEDs 28 of the groups G5 and G6 are turned off.

[2] Second Embodiment As described below, the number of groups of LEDs 28 is not limited to “6” in the first embodiment, and can be changed as appropriate.

  The image reading apparatus of the second embodiment has the same configuration as that of the image reading apparatus 1 of the first embodiment, except for the configuration mentioned below. Therefore, members that have already been described may be given the same reference numerals and descriptions thereof may be omitted.

  As shown in FIG. 8, the light source driving unit 210 can drive the LEDs 28 in 16 groups. That is, in this embodiment, n = 16. The number of LEDs 28 included in each group G1 to G16 is the same.

  As shown in FIG. 8, the areas illuminated by the groups G8, G11, and G16 on the platen glass 11 are positioned so as to straddle the edges in the main scanning direction of the A6, A5, A4 (A3) size documents. .

  In this embodiment, when the document size is detected (step S53), the LEDs 28 of the groups G8, G11, and G16 are turned on, and the other LEDs 28 are turned off. That is, the group G8 corresponds to the first group F1, the group G11 corresponds to the second group F2, and the group G16 corresponds to the third group F3.

  At the time of image reading, the light source driving unit 210 may turn on the LEDs 28 of all the groups G1 to G16 according to the control of the reading control unit 55, or the detected document to the extent that the entire document can be illuminated. You may change the group which lights up according to size.

[3] Third Embodiment The image reading apparatus according to the third embodiment has the same configuration as that of the image reading apparatus 1 according to the first embodiment, except for the configuration mentioned below. Therefore, members that have already been described may be given the same reference numerals and descriptions thereof may be omitted.

  The light source driving unit 210 is not limited to the configuration for driving the LED 28 by equally dividing it as in the first and second embodiments. For example, as shown in FIG. 9, the number of LEDs 28 included in each of the groups G1 to Gn may be different from each other. That is, the lengths in the main scanning direction of the groups G1 to Gn may be different from each other.

  In the present embodiment, n = 6, and the LED 28 that illuminates the region straddling the edge of the A6 size document is in front of the group G2 from the end of the platen glass 11 of the light source unit 21b on the origin 11a side (see FIG. LED 28 that illuminates the area across the edge of the group G1, A5 size document is the group G4, and the LED 28 between the groups G2 and G4 is the group G3, A4 (A3) size. An LED 28 that illuminates an area that crosses the edge of the document is assigned to group G6, and an LED 28 between groups G4 and G6 is assigned to group G5.

  In the present embodiment, the groups G2, G4, and G6 correspond to the first group F1, the second group F2, and the third group F3, respectively.

[4] Fourth Embodiment An image reading apparatus according to the fourth embodiment has the same configuration as that of the image reading apparatus 1 according to the second embodiment, except that the configuration of the light source control unit 53 is different. Therefore, members that have already been described may be given the same reference numerals and descriptions thereof may be omitted.

  In the first to third embodiments, the area illuminated when the document size is detected on the platen glass 11 is positioned so as to straddle the edge of the standard document on the platen glass 11, but the present invention is not limited to this.

  For example, when a document size is detected, if the area between the edges of a standard document of a different size on the platen glass 11 is illuminated, the document size can be detected even if the area across the document edge is not illuminated. It is.

  In the present embodiment, as shown in FIG. 10, the light source driving unit 210 can drive the LEDs 28 by equally dividing the LEDs 28 into 16 groups, as in the second embodiment.

  On the platen glass 11, areas illuminated by the LEDs 28 of the groups G5, G10, and G14 are the origin 11a side, the edge of the A6 document, and the edge of the A5 document in the main scanning direction. Located between the edge of the document and the edge of the A5 size document and the A4 (A3) size document.

  In the present embodiment, the groups G5, G10, and G14 correspond to the first group F1, the second group F2, and the third group F3, respectively.

  In this embodiment, the relationship between the image data and the determination result of the size detection unit 54 is as shown in Table 2.

  That is, in the present embodiment, the light source control unit 53 detects the edge of the document by turning on at least two groups of LEDs 28. As described above, the portion where the image data has changed from “white” to “black” from the origin 11a toward the main scan is recognized as the edge of the document, and the document size is determined from the position of the edge. . When the edge of the document is recognized, the LED 28 is turned on.

  In this embodiment, if the image data is “white” when any of the three groups of the first group F1 to the third group F3 is lit, the size detection unit 54 has the document edge of A4. (A3) It is determined that the image is located at the same position as the edge of the original of size.

[5] Other Embodiments (5-1) In each of the embodiments described above, the light source control unit 53 keeps the LED 28 that is once lit on during the document size detection operation. May be. That is, in step S54 of FIG. 5, the “others are extinguished” process need not be performed.

  (5-2) In each of the embodiments described above, the LEDs 28 to be lit are three groups of the first to third groups. Therefore, in step S58, the subsequent processing is performed depending on whether or not k has reached “3”. change. However, the number of groups to be lit may be other than “3”. That is, the numerical value of this determination criterion may be a numerical value other than “3”, and is appropriately set according to the maximum number of groups to be lit.

  For example, as in the first embodiment (FIG. 7), when the light source driving unit 210 drives the LED 28 by equally dividing the LED 28 into six groups, the light source control unit 53 detects all the groups G1 to G1 at the time of size detection. G6 may be lit. That is, the groups G1 to G6 correspond to the first group F1 to the sixth group F6, respectively, and the determination in step S58 is “k <6?”.

  For example, if the document size is A5, the groups G1 to G4 are sequentially turned on to perform size detection, and the size detection operation is terminated without turning on the group G5.

  (5-3) In the first to fourth embodiments, the light source control unit 53 controls the light source driving unit 210 to place two or more standard originals having different sizes on the platen glass 11 when the document size is detected. This is merely an example of the control for illuminating the installation position, and the position of the LED 28 to be lit is not limited to the first to fourth embodiments.

  By operating the light source control unit 53 in this way, it is possible to quickly determine the sizes of documents of different sizes.

  For example, when detecting the document size, an area from the edge of the standard document to a predetermined position inside the standard document may be illuminated. Referring to FIG. 9, the group G2 (first group F1) in FIG. 9 is shifted upward so that the lower end of the group G2 is located at the edge (dotted line) in the main scanning direction of the A5 size document. As long as they are arranged. Similarly, the groups G4 (second group F2) and G6 (third group F3) of FIG. 9 may be arranged so that the lower ends of the groups are positioned at the edges of A5 and A4, respectively.

  (5-5) The size detection result by the size detection unit 54 may be stored in a storage device such as an HDD (Hard Disk Drive) (not shown). Then, the light source control unit 53 may preferentially turn on the LEDs 28 of the group corresponding to the most frequently detected document size based on the past size detection result.

  For example, in the example illustrated in FIG. 7, when the number of detections of the A5 size is the largest, the number of detections of the A4 (or A3) size is the largest, and the number of detections of the A6 size is the smallest in the past, the light source control unit 53. The LED 28 in the second group F2 may be turned on first, the LED 28 in the third group F3 may be turned on, and the LED 28 in the first group F1 may be turned on last.

  (5-6) Configurations obtained by appropriately combining configurations described as different embodiments are also included in the embodiments of the present invention.

  (5-8) The number of LEDs 28 included in each group (group) is not limited to a plurality, and is appropriately set within a range of one or more. That is, the LEDs 28 may be turned on one by one from the origin 11a side.

  (5-9) The image reading apparatus of each embodiment described above may be incorporated not only in a scanner that obtains image data, but also in an apparatus such as a copying machine, a multifunction machine, or a facsimile machine.

  That is, the image reading apparatus 1 may be incorporated in the image forming apparatus 100 (FIG. 11). The image forming apparatus 100 includes an image forming unit 101 that forms an image on a recording medium (for example, paper) based on the image data obtained by the reading unit 2. As the image forming unit 101, a mechanism such as an electrophotographic system or an inkjet system can be employed.

  The present invention can be used for a scanner, a copying machine, a multifunction machine, a facsimile machine, and the like.

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Reading part 11 Platen glass (an example of a document mounting base)
210 Light source driving unit 24 Reading element 28 LED (an example of a light source)
44 Document sensor 52 Carriage control unit 53 Light source control unit 54 Size detection unit 55 Reading control unit 100 Image forming apparatus 101 Image forming unit

Claims (6)

An original table on which an original is placed;
A plurality of light sources arranged in the main scanning direction;
A light source driving unit for driving the light source;
When the document size is detected, the light source driving unit is controlled so that the light sources are driven in two or more groups, the light sources are turned on at different timings for each group, and the document is detected when the document size is detected. A light source controller that terminates the lighting of
A reading element disposed at a position for receiving light emitted from the light source and reflected by the document on the document table;
A size detection unit that detects a document size by detecting a position of an edge of the document from an output signal from the reading element;
A reading control unit that controls the light source driving unit to turn on the light source and illuminate the document during image reading;
An image reading apparatus comprising: The image reading apparatus according to claim 1, wherein the light source control unit maintains a state in which a part of the light sources of the group are turned off when the document size is detected. The light source control unit can turn on two or more light sources of the group when detecting the document size, and the placement positions of two or more standard documents having different sizes on the document placement table by the light sources of different groups. The image reading apparatus according to claim 1, wherein each of the image reading apparatuses is illuminated. The light source control unit can turn on two or more light sources of the group when detecting a document size, and an area illuminated by a light source of a different group in the document placement table is an edge of the standard document on the document placement table. The image reading apparatus according to claim 1, wherein the light source is turned on so as to straddle the position. The light source control unit is configured to detect the size of the original so that an area illuminated by the light source is disposed between edges of the standard originals having different sizes on the original placement table. The image reading device according to claim 1, wherein the image reading device is turned on. An image reading apparatus according to any one of claims 1 to 5,
An image forming unit that forms an image on a recording medium based on image data obtained by the image reading device reading an image on a document;
An image forming apparatus comprising:

Images