JP2015075645A - Image reading apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reading apparatus capable of suppressing an optical sensor from erroneously detecting a document.SOLUTION: An image reading apparatus 31 includes: a document platen 33 that has a placement surface 61 for a document G on a first surface in which a first external edge 62 of the placement surface 61 extends in a first direction X from an original point while a second external edge 63 of the placement surface 61 extends in a second direction Y that crossed the first direction X from the original point; a document-suppressing white plate 38 that swings around a rotation axis extending in the first direction X, thus capable of shifting between a close position of overlapping the placement surface 61 and a detection position of forming sharp angles relative to the placement surface 61; a reading part 44 for reading the document G placed on the placement surface 61 from a second surface side of the document platen 33, the side that is opposite to the first surface; and an optical sensor 71 for detecting the document G from the second surface side of the document platen 33. An optical axis OA of the optical sensor 71 is inclined externally from inside of the second external edge 63.

Description

  The present invention relates to an image reading apparatus such as a flatbed scanner.

  Conventionally, as an example of an image reading apparatus, an original platen glass, a reflective optical sensor that detects the presence of an original on the original platen glass from below the original platen glass, and an original presser that covers the original platen glass and presses the original. There is a flatbed scanner including a white plate (for example, Patent Document 1).

JP 2008-107610 A

  By the way, when the light sensor emits light toward the original platen glass and receives light of a predetermined threshold value or more, the light sensor reflects the detection result that the emitted light is reflected on the original and there is an original. Output. On the other hand, the optical sensor outputs a detection result indicating that there is no document when the amount of received light is less than the threshold.

  It should be noted that the detection of the original by such an optical sensor is preferably performed in an environment where a certain amount of external light enters through the original platen glass and at the same time the influence of the external light on the optical sensor is small. Generally, it is performed in a state where

  However, if the optical sensor detects the original with the original pressing white plate and the original table glass forming an acute angle, the light emitted from the optical sensor may be reflected by the original pressing white plate. Then, there is a problem that the optical sensor receives the light reflected by the original pressing white plate and outputs an erroneous detection result that there is an original, even though there is no original.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an image reading apparatus that can suppress erroneous detection of an original by an optical sensor.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
An image reading apparatus that solves the above-described problems has a document placement surface on a first surface, and a first outer edge of the placement surface extends in a first direction from an origin while a second surface of the placement surface is second. A closed position that overlaps with the above-described placement surface by rotating around an original plate that extends from the origin in a second direction that intersects the first direction, and a rotation shaft that extends in the first direction. A document holding white plate that is displaceable to a detection position that forms an acute angle with respect to the surface, and the document placed on the placement surface is read from the second surface side opposite to the first surface of the document table. A reading unit; and an optical sensor that detects the document from the second surface side of the document table, and an optical axis of the optical sensor is inclined from the inside to the outside of the second outer edge. .

  If the light sensor receives the light reflected on the white plate when the original is not placed on the placement surface, it may cause a false detection that there is an original even though there is no original. . In this respect, since the optical axis of the optical sensor is inclined from the inside to the outside of the second outer edge extending in the second direction, it is difficult to receive the light reflected by the original pressing white plate. Accordingly, it is possible to suppress erroneous detection of the document by the optical sensor caused by receiving the light reflected by the document pressing white plate.

  In the above image reading apparatus, the optical sensor is inclined from the second surface side of the document table to the placement surface, and a light projecting unit that emits light from the inner side to the outer side of the second outer edge. A light receiving portion having the optical axis, and the optical axis of the light receiving portion is separated from the original pressing white plate when the original pressing white plate is disposed at the detection position.

According to this configuration, since the optical axis of the light receiving unit does not interfere with the document pressing white plate when the optical sensor detects the document, the light receiving unit is difficult to receive the light reflected by the document pressing white plate.
In the image reading apparatus, the light projecting unit emits light from the inside to the outside of the second outer edge so that the incident angle with respect to the document table is 15 degrees or more and 45 degrees or less.

  If the incident angle of the emitted light emitted from the light projecting unit is less than 15 degrees, the light receiving unit receives the light emitted from the light projecting unit and reflected by the document table, even though there is no document. There is a risk of false detection that there is an original document. On the other hand, if the incident angle of the light emitted from the light projecting unit with respect to the document table is greater than 45 degrees, the amount of reflected light from the document received by the light receiving unit decreases, and there is no document even though there is a document. There is a risk of false detection. In that respect, according to the above configuration, the incident angle of the light emitted from the light projecting unit to the document table is 15 degrees or more and 45 degrees or less, so that the reflected light from the document is suppressed while suppressing the reflection on the document table. It is possible to receive light appropriately and suppress erroneous detection of the document.

  The image reading apparatus includes a first detection unit that detects a length of the document in the first direction, and a plurality of the optical sensors arranged in the second direction to detect the length of the document in the second direction. The first detector is disposed at a position farther from the origin than the second detector in the first direction.

  Since the optical axis of the optical sensor constituting the second detection unit is inclined from the inner side to the outer side of the second outer edge, light incident from the outer side of the second outer edge is easily received. Therefore, for example, when a photosensor that constitutes the first detection unit is arranged at a position closer to the origin than the second detection unit in the first direction, the light emitted from the light projecting unit of the same light sensor is transmitted to the second detection unit. The light sensor may receive light and cause erroneous detection of the document. In that respect, according to the above configuration, the first detection unit is arranged at a position farther from the origin than the second detection unit in the first direction, so that the second detection unit receives the light emitted from the first detection unit. It becomes difficult to do. Accordingly, it is possible to suppress erroneous detection of the document by the optical sensor that constitutes the second detection unit.

  In the image reading apparatus, the rotation shaft is disposed on the origin side of the placement surface in the second direction, a plurality of the optical sensors are disposed along the second outer edge, and the first shaft from the origin is disposed. The crossing angle of the optical axis of the optical sensor with respect to the mounting surface differs according to the distance in the two directions.

  According to this configuration, since the rotation shaft is arranged on the origin side of the placement surface in the second direction, when the document pressing white plate is at the detection position, the distance between the placement surface and the document pressing white plate is The longer the distance from the origin in the second direction, the longer. Therefore, the angle of the optical axis of the optical sensor that does not interfere with the original pressing white plate varies depending on the distance between the origin and the optical sensor in the second direction. Therefore, the angle of the optical axis of each optical sensor is optimized by setting the angle of the optical axis of the plurality of optical sensors arranged along the second direction according to the distance between the origin and the optical sensor. Can do.

The image reading apparatus includes an optical sensor housing portion that has an opening portion that opens toward the document table and houses the optical sensor, and a light absorbing member that is disposed along the opening portion.
According to this configuration, reflection of light around the opening can be suppressed by the light absorbing member disposed along the opening of the optical sensor housing that houses the optical sensor. Thereby, it is possible to suppress the erroneous detection of the document due to the light sensor receiving the light reflected around.

1 is a perspective view of a multi-function peripheral including an image reading apparatus according to an embodiment. FIG. 2 is a top view of a multifunction machine in which an opening / closing body is disposed in an open position. The top view of an image reading apparatus. FIG. 3 is a cross-sectional view illustrating a configuration of an optical sensor included in the image reading apparatus. FIG. 3 is a side view of a multifunction machine in which a document holding white plate is arranged at a detection position. The graph which shows the change of the output value of the optical sensor by the incident angle of emitted light. The table | surface which shows the relationship between the output result of an optical sensor, and the original document detected.

Hereinafter, embodiments of an image reading apparatus will be described with reference to the drawings.
The image reading device is, for example, a flat bed type scanner that constitutes a multi-function peripheral by being stacked in the vertical direction of a printer that is an example of a recording device.

  As illustrated in FIG. 1, the multifunction machine 11 according to the present embodiment includes a recording device 21 that performs printing (recording) on a recording medium S such as paper, and an image that is stacked on the recording device 21 in the vertical direction Z. A reading device 31.

  In the multifunction device 11, an operation panel 13 for operating the multifunction device 11 protrudes forward from the front side of the apparatus main body 12 in which the recording device 21 and the image reading device 31 are integrated. For example, a display unit or operation buttons for displaying a menu screen or the like can be arranged on the operation panel 13.

  A cover member 14 that covers an opening (not shown) for inserting the recording medium S is provided on the back side of the apparatus main body 12. A discharge unit 15 for discharging the recording medium S is provided on the front side of the apparatus main body 12 at a position below the operation panel 13 in the vertical direction Z. A storage cassette 17 that stores a plurality of recording media S in a stacked state is detachably attached to the lower portion of the apparatus main body 12.

  As shown in FIG. 2, the image reading device 31 includes a bottomed box-shaped reading unit case 32, a document table 33 and a reading table 34 fitted in the upper opening of the reading unit case 32, and a document table 33 and a reading unit. A frame member 35 for fixing the base 34 and an opening / closing body 37 rotatably attached via a hinge 36 provided on the back side are provided.

  The document table 33 and the reading table 34 can be made of, for example, a square plate-shaped transparent glass. The reading table 34 is shorter than the document table 33 in the longitudinal direction (left and right direction in FIG. 2) of the apparatus main body 12. The reading table 34 is arranged on one side (left side in FIG. 2) of the document table 33 in the longitudinal direction of the apparatus main body 12.

  The opening / closing body 37 is, for example, an auto document feeder that feeds a plurality of stacked originals G onto the reading table 34 while inverting one by one. A document pressing white plate 38 for pressing the document G placed on the document table 33 is attached to the opening / closing body 37. The opening / closing body 37 may be a plate-shaped lid member provided with a document pressing white plate 38. When the opening / closing body 37 is a lid member that does not function as an auto document feeder, the reading table 34 may not be provided.

  The document table 33 has a rectangular placement surface 61 on which the document G is placed on the first surface which is the upper surface in the present embodiment. The mounting surface 61 is one end in the longitudinal direction of the apparatus main body 12 (left end in FIG. 2), and in the depth direction intersecting with the longitudinal direction, the base end on the back side near the rotation axis AX of the opening / closing body 37. The origin OP is set.

  The first outer edge 62 of the mounting surface 61 extends from the origin OP in the first direction X (the right direction that is the longitudinal direction of the apparatus main body 12 in the present embodiment), while the second outer edge of the mounting surface 61 63 extends from the origin OP in a second direction Y (in the present embodiment, a forward direction opposite to the depth direction of the apparatus main body 12) intersecting the first direction. The placement surface 61 has a third outer edge 64 at a position facing the first outer edge 62, and a fourth outer edge 65 at a position facing the second outer edge 63.

  A rotation axis AX of the opening / closing body 37 is disposed on the origin OP side of the mounting surface 61 in the second direction Y of the apparatus main body 12 and extends along the first direction X. The original pressing white plate 38 is configured to be displaceable between a closed position overlapping the placement surface 61 and an open position away from the placement surface 61 when the opening / closing body 37 rotates about the rotation axis AX. It has become. In FIG. 2, in order to clearly show the document pressing white plate 38, a state in which the opening / closing body 37 is widened so that the document pressing white plate 38 forms an obtuse angle with the placement surface 61 is illustrated. Need only be open to the extent that the document G can be placed on the placement surface 61.

  The image reading device 31 includes a first opening / closing lever 66 disposed behind the document table 33 in the depth direction along the second direction Y, and a position closer to the rotation axis AX than the first opening / closing lever 66 in the depth direction. A second opening / closing lever 67 arranged at the position is provided so as to protrude from the frame member 35.

  As shown in FIG. 3, a guide rail 41 extending in the first direction X protrudes from the bottom of the reading unit case 32. In FIG. 3, the reading table 34 and the frame member 35 are not shown and the document table 33 is indicated by a dotted line in order to clearly show the configuration inside the reading unit case 32.

  A reading carriage 42 is accommodated in the reading unit case 32. The reading carriage 42 has an engaging portion 43 that engages with the guide rail 41, and is supported by the guide rail 41 via the engaging portion 43. The reading carriage 42 is equipped with a reading unit 44 that reads the document G placed on the document table 33 from the second surface side (the lower surface side in the present embodiment) opposite to the first surface of the document table 33. . The reading unit 44 is, for example, a contact type image sensor.

  The reading carriage 42 is reciprocated along the first direction X, which is the scanning direction, by being guided by the guide rail 41. Note that the engaging portion 43 of the reading carriage 42 with respect to the guide rail 41 is preferably arranged in the vicinity of the center of gravity of the reading carriage 42, so the engaging portion 43 is near the center in the longitudinal direction (second direction Y) of the reading carriage 42. Is arranged.

  A plurality of optical sensors 71 that detect a document placed on the placement surface 61 from the second surface side of the document table 33 are disposed on the bottom of the reading unit case 32. A plurality (two in this embodiment) of optical sensors 71X (71X1, 71X2) arranged in the first direction X constitute a first detection unit 68 for detecting the length of the document G in the first direction X. A plurality (five in the present embodiment) of optical sensors 71Y (71Y1, 71Y2, 71Y3, 71Y4, 71Y5) arranged in the second direction Y detect the length of the document G in the second direction Y. 2 detection part 69 is comprised.

  The optical axis OA of the optical sensor 71X constituting the first detection unit 68 is inclined from the inner side to the outer side of the fourth outer edge 65. As a result, the detection position DX of the document G by the first detection unit 68 (that is, the position where the optical axis OA of the optical sensor 71X and the placement surface 61 intersect) is the optical sensor 71X and the fourth in the first direction X. Between the outer edge 65 and the outer edge 65.

  On the other hand, the optical axis OA of the optical sensor 71 </ b> Y constituting the second detection unit 69 is inclined from the inner side to the outer side of the second outer edge 63. As a result, the detection position DY of the document G by the second detection unit 69 (that is, the position where the optical axis OA of the optical sensor 71Y intersects the placement surface 61) is the second sensor X in the first direction X and the second sensor sensor Y. Between the outer edge 63 and the outer edge 63.

  The plurality of optical sensors 71 </ b> Y constituting the second detection unit 69 are arranged along the second outer edge 63. Further, the first detection unit 68 is arranged in a position farther from the origin OP than the second detection unit 69 in the first direction X. The optical sensor 71 </ b> X constituting the first detection unit 68 emits light toward the outside of the fourth outer edge 65.

  As shown in FIG. 4, the optical sensor 71 includes a light projecting unit 75 that emits light from the second surface side of the document table 33 toward the placement surface 61, and a document G placed on the placement surface 61. And a light receiving portion 76 for receiving the reflected light. Therefore, the optical axis OA of the optical sensor 71 indicates at least one of the optical axis OA1 of the light projecting unit 75 and the optical axis OA2 of the light receiving unit 76. However, in this embodiment, since the optical axis OA1 of the light projecting unit 75 and the optical axis OA2 of the light receiving unit 76 are set to be substantially parallel, the inclination angle of the optical axis OA1 with respect to the placement surface 61 is The inclination angle of the optical axis OA2 with respect to the placement surface 61 is equal.

  The optical sensor 71 is accommodated in an optical sensor accommodating portion 73 having an opening 72 that opens toward the document table 33. A black sheet as the light absorbing member 74 is disposed along the opening 72 of the optical sensor housing 73.

Next, the operation of the image reading apparatus 31 configured as described above will be described.
Since the light sensor 71 detects the presence or absence of the document G when the light receiving unit 76 receives the reflected light from the document G, for example, when external light reflected in the reading unit case 32 enters the light receiving unit 76 excessively. There is a risk of erroneous detection that there is a document G even though there is no document G.

  In this regard, in the present embodiment, by arranging the light absorbing member 74 around the optical sensor 71, reflection of light at the bottom of the reading unit case 32 is suppressed, and thus erroneous detection of the optical sensor 71 is suppressed. .

  In the present embodiment, as shown in FIG. 3, in addition to the periphery of the optical sensor 71, the guide rail 41 and the third outer edge 64 in a position where the external light easily enters at the bottom of the reading unit case 32, for example, in the second direction Y. The light absorbing member 74 is arranged in a wide range between the two. In addition, a light absorbing member 74 is disposed between the guide rail 41 and the first outer edge 62 in the second direction Y at a position close to the optical sensor 71. Thereby, reflection of light at the bottom of the reading unit case 32 is further suppressed.

  That is, when the document G is detected by the optical sensor 71, the opening / closing body 37 is disposed at the open position so that the light emitted from the light projecting unit 75 passes through the document table 33 when there is no document G, and It is necessary to prevent light from entering excessively. In order to prevent external light from entering excessively with the opening / closing body 37 in the open position, the open position where the document pressing white plate 38 forms an acute angle with respect to the placement surface 61 is set as the detection position. Is preferred.

  For example, as shown in FIG. 5, an open position where the document pressing white plate 38 forms 30 degrees with respect to the placement surface 61 is set as a detection position. The opening / closing body 37 can be opened to a position where the angle formed by the document pressing white plate 38 and the placement surface 61 becomes larger than the detection position. Then, the angle formed between the document pressing white plate 38 and the placement surface 61 is larger than 30 degrees, and the positions of the document pressing white plate 38 and the opening / closing body 37 when the document G is placed on the placement surface 61 are fully opened. And

  On the other hand, the position of the opening / closing body 37 when the document pressing white plate 38 is in the detection position is defined as a half-open position. That is, the opening / closing body 37 is displaced between the fully open position and the closed position by rotating about the rotation axis AX, and has a detection position at a midway position rotating from the fully open position toward the closed position. .

  Here, when the optical sensor 71 detects the document G, external light may be reflected by the document pressing white plate 38 and enter the placement surface 61 as indicated by an arrow in FIG. When the light receiving unit 76 shown in FIG. 4 receives such external light, the optical sensor 71 may erroneously detect that there is a document G even though there is no document G.

  Further, when the optical sensor 71 receives the light reflected by the original pressing white plate 38 and transmitted through the original table 33 when the original G is not placed on the placement surface 61, the original is sent even though there is no original. There is a risk of false detection that there is.

  In this regard, as shown in FIG. 3, in the present embodiment, in the first detection unit 68, the optical axis OA of the optical sensor 71 </ b> X is inclined from the inner side to the outer side of the fourth outer edge 65. 76 is difficult to receive the light reflected by the document holding white plate 38. Further, in the second detection unit 69, the optical axis OA of the optical sensor 71Y is inclined from the inner side to the outer side of the second outer edge 63, so that the light receiving unit 76 receives the reflected light from the document pressing white plate 38. Hard to do. For this reason, the light sensor 71 receives the reflected light from the document pressing white plate 38 and suppresses erroneous detection that the document G is present even though the document G is not present.

  As shown in FIG. 4, the optical axis OA2 of the light receiving unit 76 of the optical sensor 71Y is positioned away from the original pressing white plate 38 when the original pressing white plate 38 is disposed at the detection position. It is preferable that the intersection angle θc between the OA 2 and the placement surface 61 is set. If the document holding white plate 38 at the detection position and the optical axis OA2 of the light receiving unit 76 intersect, the light receiving unit 76 receives the reflected light from the document holding white plate 38 and the document G is not present even though there is no document G. It is because there exists a possibility of misdetecting that there exists G.

  However, even if the original pressing white plate 38 and the optical axis OA2 of the light receiving unit 76 are not separated from each other, the optical axis OA of the optical sensor 71 extends from the inside to the outside of the outer edges 63 and 65 of the mounting surface 61 extending in the second direction Y. Since the optical sensor 71 is less likely to receive the reflected light from the original pressing white plate 38 by tilting it toward, an effect of suppressing erroneous detection can be expected.

  Further, the light projecting unit 75 and the light receiving unit 76 of the optical sensor 71Y are arranged side by side in the first direction X. In order to make it difficult to receive the reflected light from the original pressing white plate 38, the light receiving unit 76 projects the light. It is preferable to dispose the second outer edge 63 closer to the second direction 63 than the portion 75 in the first direction X.

  With such an arrangement, the optical axis OA of the optical sensor 71Y is inclined from the inner side to the outer side of the second outer edge 63. As a result, the light receiving unit 76 is located farther from the document table 33 than the light projecting unit 75. In the embodiment, it is arranged on the lower side in the vertical direction). This is preferable because unnecessary light that causes erroneous detection, such as external light transmitted through the document table 33, is difficult to reach the light receiving unit 76.

Further, the incident angle θi of the emitted light will be described in relation to the inclination of the optical axis OA of the optical sensor 71.
In the case where the light receiving unit 76 of the optical sensor 71 includes a photodiode, a current corresponding to the amount of received light flows, so that the amount of received light can be output as a voltage signal. Therefore, for example, when the voltage value VP output from the light receiving unit 76 is equal to or greater than the threshold value, the detection result (for example, the presence of the original G is assumed to have received the light reflected by the original G on the placement surface 61). , “1”) is output by the optical sensor 71. On the other hand, when the voltage value VP output from the light receiving unit 76 is less than the threshold value, the optical sensor 71 outputs a detection result (for example, “0”) that there is no document G.

  The threshold used for detecting the document G is set based on the reflectance of white paper that is frequently used as the document G, for example. However, when the emitted light is reflected on the document table 33 or the external light is transmitted through the placement surface 61 of the document table 33 and enters the document table 33, the voltage value VP is determined depending on whether or not the document G is present. There is a possibility that the difference becomes small and erroneous detection occurs.

  FIG. 6 shows an example of a change in the output value of the optical sensor 71 depending on the incident angle θi of the outgoing light. The voltage value VP when the original G is not on the placement surface 61 is G (0), and the outgoing light is applied to the original G. The voltage value VP when reflected is G (1), and the voltage value VP when outgoing light is reflected by the original pressing white plate is 38.

  As shown in FIG. 6, when the incident angle θi of the emitted light with respect to the placement surface 61 is smaller than 15 degrees, the light receiving unit 76 receives the emitted light reflected by the document table 33, and therefore G (0 ), A voltage value VP of the same level as that of G (1) where the original G is present is output. That is, if the incident angle θi of the emitted light with respect to the document table 33 is smaller than 15 degrees, the optical sensor 71 may erroneously detect that the document G is present even though the document G is not present.

  On the other hand, if the incident angle θi of the emitted light with respect to the document table 33 is greater than 45 degrees, the amount of reflected light from the document G received by the light receiving unit 76 decreases, and therefore G (0) without the document G and the document G The difference in voltage value VP from G (1) becomes smaller. That is, if the incident angle θi of the emitted light with respect to the document table 33 is larger than 45 degrees, the optical sensor 71 may erroneously detect that there is no document G even though the document G exists.

  Therefore, in order to appropriately receive the reflected light with respect to the original G while suppressing the reflection of the outgoing light on the original table 33, the incident angle θi of the light emitted from the light projecting unit 75 with respect to the original table 33 is 15 degrees. It is preferably 45 degrees or less. In order to further suppress the influence of reflection on the document table 33, it is more preferable that the incident angle θi of the emitted light is 25 degrees or more and 45 degrees or less.

  In the present embodiment, the first condition that the original pressing white plate 38 at the detection position and the optical axis OA2 of the light receiving unit 76 do not intersect with each other, and the incident angle θi of the emitted light is 15 degrees or more and 45 degrees or less. The intersection angle θc of the optical axis OA (OA1, OA2) of the optical sensor 71 with respect to the document table 33 is set to 60 degrees so as to satisfy both of the two conditions. At this time, the incident angle θi of the emitted light with respect to the document table 33 is 30 degrees.

Next, the operation of the image reading device 31 will be described.
When reading the document G, first, the opening / closing body 37 is disposed at the fully open position so that the surface of the document G to be read faces the placement surface 61 and the corner of the document G is positioned at the origin OP. The original G is placed on the original table 33 while being aligned with the original position.

  When the placement of the original G is completed, the opening / closing body 37 in the fully open position is rotated toward the closed position. Then, when the opening / closing body 37 rotates from the open position to the half-open position, the opening / closing body 37 presses the first opening / closing lever 66, thereby detecting that the original pressing white plate 38 is disposed at the detection position. When the document pressing white plate 38 is disposed at the detection position, the light sensor 71 emits light from the light projecting unit 75 and receives light as a detection operation for detecting the document G placed on the placement surface 61. A detection result based on the amount of light received by the unit 76 is output.

  For example, when the light intensity of light received by the light receiving unit 76 when the light projecting unit 75 emits light toward the mounting surface 61 is greater than or equal to the threshold value, the light sensor 71 outputs the mounting surface. As a result of reflection on the original G on 61, a detection result “1” indicating that there is an original G is output. On the other hand, when the amount of light received by the light receiving unit 76 is less than the threshold, a detection result “0” indicating that there is no document G is output.

  Then, as shown in FIG. 7, the optical sensor 71Y1, 71Y2, 71Y3, 71Y4, 71Y5, 71X1, 71X2 is mounted on the mounting surface 61 based on the combination of detection results (“1” or “0”). The size and orientation of the original G are detected. If all the optical sensors 71 output “0”, a detection result indicating that there is no document G is obtained.

  When the first direction X is the horizontal direction and the second direction Y is the vertical direction, when the document G is placed so that the first direction X is the longitudinal direction, the original G is placed horizontally, and the second direction Y is the longitudinal direction. When the original G is placed so that 3 and 7, the original G (A5S) is horizontally placed in A5 size, the original G (A4L) is vertically placed in A4 size, the original G (B5S) is horizontally placed in B5 size, and the original G (A4S). Means A4 size landscape, document G (B4S) means B4 size landscape, and document G (A3S) means A3 size landscape.

  In other words, the optical sensors 71X1, 71X2, 71Y1, 71Y2, 71Y3, 71Y4, 71Y5 overlap the corresponding original G in plan view so that the original G of a plurality of sizes and the orientation of the original G can be discriminated. Placed in position.

  Subsequently, when the opening / closing body 37 further rotates from the detection position and pushes the second opening / closing lever 67, it is detected that the document pressing white plate 38 is disposed at the closed position. Note that the optical sensor 71 may perform the detection operation again when the document holding white plate 38 is disposed at the closed position. When performing the detection operation twice in this way, for example, the optical sensor 71 detects based on the difference between the light reception amount in the first detection operation and the light reception amount in the second detection operation. Output the result.

  Here, at the time of the second detection operation, the document pressing white plate 38 is overlaid on the document G, so that the optical sensor 71 detects the document G placed on the placement surface 61 or the document pressing white plate. The outgoing light reflected by 38 is received. As shown in FIG. 6, since the document pressing white plate 38 has reflection characteristics similar to those of the document G, all the light sensors 71 receive light in the second detection operation performed by placing the document pressing white plate 38 in the closed position. The amount should be the same value as when there is paper.

  Therefore, for example, when the reflected light from the document G is received in the first detection operation, the difference between the light reception amount in the first detection operation and the light reception amount in the second detection operation is zero. Close value. Accordingly, in this case, the optical sensor 71 outputs a detection result “1” indicating that the document G is present.

  On the other hand, when the reflected light from the document G is not received in the first detection operation, the absolute value of the difference between the light reception amount in the first detection operation and the light reception amount in the second detection operation is The value is close to the amount of light received when the document G is present. Therefore, in this case, the optical sensor 71 outputs a detection result “0” indicating that there is no document G.

  However, for example, if the light projecting unit 75 of the optical sensor 71 does not emit light or if the light receiving sensitivity of the light receiving unit 76 decreases due to deterioration over time, the amount of light received by the optical sensor 71 decreases. That is, when the amount of light received by the optical sensor 71 in the second detection operation performed by placing the document pressing white plate 38 in the closed position is small, it is suspected that the optical sensor 71 is in a defective state. Therefore, by detecting the original G by two detection operations, a more accurate detection result can be obtained.

  When the detection operation by the optical sensor 71 is completed and the opening / closing body 37 is disposed at the closed position, the reading carriage 42 scans and is mounted on the reading carriage 42 based on the detected size and orientation of the document G. The read unit 44 reads the original G.

According to the above embodiment, the following effects can be obtained.
(1) Since the optical axis OA of the optical sensor 71Y is inclined from the inner side to the outer side of the second outer edge 63 extending in the second direction Y, it is difficult to receive the light reflected by the original pressing white plate 38. Therefore, erroneous detection of the original G by the optical sensor 71Y caused by receiving the light reflected by the original pressing white plate 38 can be suppressed.

  (2) Since the optical axis OA2 of the light receiving unit 76 does not interfere with the document pressing white plate 38 when the optical sensor 71Y detects the document G, the light receiving unit 76 hardly receives the light reflected by the document pressing white plate 38.

  (3) Since the incident angle θi of the light emitted from the light projecting unit 75 with respect to the document table 33 is not less than 15 degrees and not more than 45 degrees, the reflected light from the document G is appropriately controlled while suppressing the reflection on the document table 33. The erroneous detection of the original G can be suppressed.

  (4) Since the optical axis OA of the optical sensor 71Y constituting the second detection unit 69 is inclined from the inner side to the outer side of the second outer edge 63, the light incident from the outer side of the second outer edge 63 is received. It's easy to do. Therefore, for example, when the optical sensor 71X constituting the first detection unit 68 is disposed at a position closer to the origin OP than the second detection unit 69 in the first direction X, the light projecting unit 75 of the optical sensor 71X is emitted. There is a possibility that the light sensor 71Y of the second detection unit 69 receives the light and causes erroneous detection of the document G. In that respect, according to the embodiment described above, the first detection unit 68 is arranged at a position farther from the origin OP than the second detection unit 69 in the first direction X, and thus the light emitted by the first detection unit 68 is emitted. The second detector 69 is less likely to receive light. Therefore, erroneous detection of the original G by the optical sensor 71Y constituting the second detection unit 69 can be suppressed.

  (5) Light reflection around the opening 72 can be suppressed by the light absorbing member 74 disposed along the opening 72 of the light sensor housing 73 that houses the light sensor 71. Thereby, it is possible to suppress erroneous detection of the document G caused by the light sensor 71 receiving light reflected by the surroundings.

In addition, you may change the said embodiment as follows.
When a plurality of optical sensors 71Y are arranged along the second direction Y, the mounting surface of the optical axis OA2 of the light receiving unit 76 according to the distance in the second direction Y from the origin OP of the optical sensor 71Y. The crossing angle θc with respect to 61 may be different. In other words, the distance between the placement surface 61 and the original pressing white plate 38 becomes longer as the distance from the origin OP in the second direction Y increases. The shorter the distance between the placement surface 61 and the document pressing white plate 38, the easier the optical axis of the optical sensor 71Y intersects with the document pressing white plate 38. Therefore, as the distance in the second direction Y from the origin OP of the optical sensor 71Y is longer, even if the intersection angle θc of the optical axis OA2 with respect to the placement surface 61 is increased, the original pressing white plate 38 located at the detection position with the optical axis OA2. And can not be crossed.

  That is, since the rotation axis AX is disposed on the origin OP side of the placement surface 61 in the second direction Y, when the document pressing white plate 38 is in the detection position, the placement surface 61 and the document pressing white plate 38 The distance increases as the distance from the origin OP in the second direction Y increases. Therefore, the angle of the optical axis OA of the optical sensor 71 that does not interfere with the original pressing white plate 38 varies depending on the distance between the origin OP and the optical sensor 71 in the second direction Y. Therefore, by setting the angle of the optical axis OA of the plurality of optical sensors 71Y arranged along the second direction Y according to the distance between the origin OP and the optical sensor 71Y, the optical axis OA of each optical sensor 71Y. The angle can be optimized.

  Further, as the distance from the origin OP of the optical sensor 71Y in the first direction X is shorter, the optical axis OA2 and the original pressing white plate 38 at the detection position are less likely to intersect with each other. The longer the distance from, the longer the distance from the origin OP of the optical sensor 71Y in the first direction X may be.

  From the viewpoint of suppressing erroneous detection of the document G due to the influence of reflected light from the document holding white plate 38, the optical axis OA1 of the light projecting unit 75 and the optical axis of the light receiving unit 76 as the optical axis OA of the optical sensor 71Y. Of OA2, at least the optical axis OA2 of the light receiving portion 76 only needs to be inclined from the inner side to the outer side of the second outer edge 63.

  That is, the optical sensor 71 detects the document G in a region where the optical axis OA1 of the light projecting unit 75 and the optical axis OA2 of the light receiving unit 76 are not parallel, and the optical axis OA1 and the optical axis OA2 intersect. Also good. In this case, an optimum angle can be set between the optical axis OA1 of the light projecting unit 75 and the optical axis OA2 of the light receiving unit 76.

  For example, when the bottom of the reading unit case 32 is black, reflection of light at the bottom of the reading unit case 32 can be suppressed without arranging the light absorbing member 74 around the optical sensor 71. . Note that the distance between the placement surface 61 and the original pressing white plate 38 increases as the distance from the origin OP in the second direction Y increases. Therefore, when the document pressing white plate 38 is at the detection position, the influence of the external light reflected on the document pressing white plate 38 and incident on the placing surface 61 as shown by an arrow in FIG. The closer you are, the bigger it will be. Therefore, in the case where reflection of light in the reading unit case 32 is suppressed by measures such as the arrangement of the light absorbing member 74 or black paint, the origin OP is set in the second direction Y in addition to the periphery of the optical sensor 71. It is preferable to apply the same countermeasure to the bottom of the near reading unit case 32.

  In the mounting surface 61, the outer edges 63 and 65 extending in the second direction Y may be longer than the outer edges 62 and 64 extending in the first direction X, and the lengths of the outer edges 62 and 64 and the outer edges 63 and 65 may be longer. May be equal. Moreover, the shape of the mounting surface 61 may not be rectangular.

  The number and arrangement of the optical sensors 71 can be arbitrarily changed according to the size and orientation of the original G to be detected. For example, only one optical sensor 71Y may be provided to detect only the presence or absence of the document G.

  The recording device 21 provided in the multifunction machine 11 is not limited to a printer, and may be, for example, a facsimile or a copying machine. Further, the image reading device 31 is not limited to a scanner, and may be, for example, a card reader or an authentication device.

  G: Document, X: First direction, Y: Second direction, θc: Crossing angle, θi: Incident angle, AX: Rotating axis, OA, OA1, OA2 ... Optical axis, OP ... Origin, 31 ... Image reading device , 33 ... document table, 38 ... document pressing white plate, 44 ... reading unit, 61 ... placement surface, 62 ... first outer edge, 63 ... second outer edge, 68 ... first detection unit, 69 ... second detection unit , 71, 71X, 71Y, 71X1, 71X2, 71Y1, 71Y2, 71Y3, 71Y4, 71Y5 ... optical sensor, 72 ... opening, 73 ... photosensor housing, 74 ... light absorbing member, 75 ... light projecting unit, 76 ... Light receiving section.

Claims (6)

The first surface has a document placement surface, and the first outer edge of the placement surface extends in the first direction from the origin, while the second outer edge of the placement surface extends from the origin to the first direction. A document table extending in a second direction that intersects;
A document holding white plate that is displaceable between a closed position that overlaps the placement surface and a detection position that forms an acute angle with respect to the placement surface by pivoting about a pivot shaft extending in the first direction;
A reading unit that reads the document placed on the placement surface from a second surface side opposite to the first surface of the document table;
An optical sensor for detecting the document from the second surface side of the document table;
With
An image reading apparatus, wherein an optical axis of the optical sensor is inclined from the inside to the outside of the second outer edge. The optical sensor includes a light projecting unit that emits light from the second surface side of the document table toward the placement surface, and the optical axis that is inclined from the inner side to the outer side of the second outer edge. A light receiving portion,
The image reading apparatus according to claim 1, wherein the optical axis of the light receiving unit is separated from the original pressing white plate when the original pressing white plate is disposed at the detection position.   The light projecting unit emits light from the inside to the outside of the second outer edge so that an incident angle with respect to the document table is 15 degrees or more and 45 degrees or less. Image reading apparatus. A first detector for detecting a length of the document in the first direction;
A second detection unit including a plurality of the optical sensors arranged in the second direction in order to detect the length of the document in the second direction;
The said 1st detection part is arrange | positioned in the said 1st direction in the position away from the said origin rather than the said 2nd detection part, The Claim 1 characterized by the above-mentioned. Image reading device. The pivot shaft is disposed on the origin side of the placement surface in the second direction,
A plurality of the optical sensors are arranged along the second outer edge, and an intersection angle of the optical axis of the optical sensor with respect to the mounting surface is different according to a distance in the second direction from the origin. The image reading apparatus according to any one of claims 1 to 4. An optical sensor accommodating portion for accommodating the optical sensor having an opening that opens toward the document table;
The image reading apparatus according to claim 1, further comprising a light absorbing member disposed along the opening.