JP5826334B2 - Image reading apparatus and image forming apparatus equipped with the same - Google Patents

Description

  The present invention relates to an image reading apparatus used for a copying machine, an image scanner, and the like. The present invention also relates to an image forming apparatus equipped with the image reading apparatus.

  In general, an image reading apparatus used in a copying machine, an image scanner, or the like irradiates light toward a document placed on a contact glass or placed on a contact glass, and reflects the reflected light. The image data received and read on the surface of the document is read. The contact glass is made of transparent glass and is provided at a location on the upper surface of the apparatus main body. Inside the device body below the contact glass, there are provided a light source that emits light toward the document, a mirror for guiding the reflected light in a predetermined direction, an optical member such as an imaging lens, a line sensor that is an image sensor, and the like. ing.

  Some image reading apparatuses have a function of automatically measuring the size of a document placed on a contact glass. Various methods for measuring the document size have been proposed in the past, but in general, a plurality of sensors corresponding to the document size are arranged at appropriate positions in the image reading apparatus, or the document size is measured. A method of performing a scanning operation for reading image data and measuring a document size using a line sensor is employed.

  Examples of the prior art for measuring the size of a document placed on a contact glass can be seen in Patent Documents 1 and 2. In the copying machine described in Patent Document 1, a plurality of document size detection sensors are dispersedly arranged at predetermined positions below the document table in order to detect the size of the document placed on the document table. The image reading apparatus described in Patent Document 2 receives reflected light emitted from a light source toward a document by a line sensor, and determines a document size based on the output of the line sensor.

JP-A-10-282737 JP-A-11-75025

  However, since the copying machine described in Patent Document 1 has a document size detection sensor arranged corresponding to a fixed size such as B5 or A4, there is a possibility that an irregular document size cannot be detected. As a result, the user may have to measure the irregular original size by himself or manually input the measured paper size into the apparatus, which may be time-consuming.

  A line sensor used for reading image data of a document generally images reflected light from the surface of the document as white pixels. In order to identify the edge of the document, it is necessary to image the periphery of the document as pixels other than white, for example, black pixels. Therefore, the automatic measurement of the document size using the line sensor is executed before closing the document presser (platen cover or the like) provided to be openable and closable with respect to the contact glass. In the case of the image reading apparatus described in Patent Document 2, light is irradiated by a light irradiation unit (light source) having substantially the same length as one side of the contact glass in order to determine the document size, so that it is shorter than one side of the contact glass. When a document of a size is placed on the contact glass, there is a high possibility that light leaks from the outside of the document to the user side. As a result, the user may feel very dazzled and feel uncomfortable, and the work efficiency may be reduced.

  The present invention has been made in view of the above points, and can suppress the user's dazzling feeling when measuring the document size, and can easily perform the measurement of the irregular document size easily and automatically. An object of the present invention is to provide an image reading apparatus capable of improving work efficiency. It is another object of the present invention to provide an image forming apparatus equipped with such an image reading apparatus.

  In order to solve the above-described problems, an image reading apparatus according to the present invention includes a document table on which an original is placed and a reference point for placing the document so that the corners of the document are aligned. A light irradiating unit disposed below and having a plurality of light sources including one or a plurality of light emitting elements, the light sources being arranged linearly in the main scanning direction, and irradiating light toward the original; and perpendicular to the main scanning direction A scanning drive unit for moving the light irradiation unit in the sub-scanning direction, an image sensor that receives reflected light that is irradiated from the light irradiation unit and reflected by the document surface, and controls the scan drive unit Then, the light irradiation unit is moved in the sub-scanning direction, and each of the plurality of light sources of the light irradiation unit is individually turned on or off sequentially in the main scanning direction, and information from the image sensor that receives the reflected light Based on said criteria The edge of the document facing the main scanning direction is identified, the size of the document in the main scanning direction is measured from the distance between the edge and the reference point, and then the document is opposed to the reference point. A control unit for identifying an end portion of the document in the sub-scanning direction and measuring a size of the document in the sub-scanning direction from a distance between the end portion and the reference point.

  According to this configuration, the image forming apparatus turns on and off each of the plurality of light sources arranged in the main scanning direction individually in turn, while the end of the document in the main scanning direction and the end of the sub scanning direction. Perform part identification. Therefore, there are relatively few light sources that are lit in the area outside the edge of the document when measuring the document size.

  In the image reading apparatus having the above-described configuration, the control unit performs main scanning with the light sources that are turned on and the light sources that are turned off in the initial stage of moving the light irradiation unit in the sub-scanning direction. The light source is turned on or off in order so as to be alternately arranged along the direction, and then the light irradiation unit is moved a predetermined distance in the sub-scanning direction, and then the light source is turned on and off to switch two or more in the sub-scanning direction. The edge of the document in the main scanning direction is identified based on the information from the image sensor that has received the reflected light at the position, and the document is located in an area where the document exists with respect to the edge in the main scanning direction. The end of the document in the sub-scanning direction is determined based on information from the image sensor that receives reflected light when the light irradiating unit is continuously moved in the sub-scanning direction with one light source turned on. identification Was Rukoto.

  According to this configuration, in the initial stage when measuring the document size, the plurality of light sources are individually turned on or off alternately along the main scanning direction, and then the lighting and extinguishing of the documents are switched. An end in the main scanning direction is identified. Thereafter, one light source located in the area where the document exists is turned on to identify the end of the document in the sub-scanning direction. Therefore, when identifying the end of the document in the main scanning direction, only about half the light source of the light irradiating unit is turned on. Further, the light source is not turned on in an area outside the end of the document in the main scanning direction except for a short period until the end of the document in the main scanning direction is identified.

  Note that the “predetermined distance” described here is an arbitrary distance determined in advance with respect to the movement of the light irradiation unit in the sub-scanning direction in the initial stage of document size measurement. The “predetermined distance” can be set to an arbitrary distance such as 5 mm, 10 mm, and 15 mm, for example, and can be appropriately set as necessary. Therefore, in the embodiment described later, the “predetermined distance” is set to “5 mm”, for example, but is not limited to such a distance. Further, for example, the “predetermined distance” may be set as a distance corresponding to an equal multiple of the length (width) of the light irradiation unit in the sub-scanning direction.

  In the image reading apparatus having the above-described configuration, the control unit turns on the light irradiation unit after turning on the light sources at both ends in the main scanning direction at an initial stage of moving the light irradiation unit in the sub-scanning direction. Based on information from the image sensor that has received reflected light when the light sources are turned on one by one from each end in the main scanning direction to the other end while moving in the sub-scanning direction. The end in the main scanning direction and the end in the sub scanning direction are identified.

  According to this configuration, the light sources are turned on one by one at both ends in the main scanning direction in the initial stage when measuring the document size. Then, the light irradiation unit is moved in the sub-scanning direction, and the two lit light sources are sequentially moved toward the other end in the main scanning direction. Therefore, only two light sources are required to be lit in the area outside the edge of the document when measuring the document size.

  Further, in the image reading apparatus having the above-described configuration, the image reading apparatus includes a document press provided to be openable and closable with respect to the document table, and an open / close detection unit for detecting an open / close operation of the document press, and the control unit includes: Measuring the size of the document in the main scanning direction and the size of the document in the sub-scanning direction on the condition that the opened document presser is tilted to a predetermined angle in the closing direction based on information from the open / close detection unit It was decided to start.

  According to this configuration, the manuscript size is automatically started as the manuscript presser is tilted from the open state to the closing direction. Since document size measurement is started with the document retainer being opened to some extent, it is easy to identify the edge of the document.

  The “predetermined angle” described here is a predetermined arbitrary angle of the document pressing with respect to the document table that determines the start timing of the document size measurement. The “predetermined angle” can be set to an arbitrary angle such as 45 degrees, 30 degrees, and 25 degrees, for example, but can be appropriately set as necessary. Therefore, in the embodiments described later, the “predetermined angle” is set to “30 degrees”, for example, but is not limited to such an angle.

  In the present invention, the image reading apparatus is mounted on the image forming apparatus.

  According to this configuration, in the image forming apparatus, when the document size is measured, the number of light sources that are turned on in an area outside the edge of the document is relatively small.

  According to the configuration of the present invention, when measuring the document size, each of the plurality of light sources of the light irradiating unit is individually turned on or off in the main scanning direction in order, so that the end of the irregular document size can be easily measured. can do. Furthermore, since the number of light sources that are turned on in the area outside the edge of the document is relatively small, it is possible to prevent light from leaking from the outside of the document to the user side. Therefore, it is possible to prevent the user from being dazzled when measuring the document size, and to improve the work efficiency that can easily and automatically perform the measurement of the irregular document size. An image reading apparatus can be provided. It is also possible to provide an image forming apparatus equipped with such an image reading apparatus.

1 is a schematic vertical sectional front view of an image forming apparatus equipped with an image reading apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus in FIG. 1. FIG. 2 is a partial vertical cross-sectional front view of the periphery of the image reading apparatus of the image forming apparatus illustrated in FIG. 1. It is a top view of the light irradiation part of the image reading apparatus shown in FIG. FIG. 4 is a right side view of a schematic vertical cross section around the image reading apparatus in FIG. 3. FIG. 6 is a model vertical cross-section right side view around the image reading apparatus similar to FIG. 6 is a flowchart illustrating an operation related to document size measurement of the image reading apparatus according to the first embodiment. FIG. 6 is a top view showing the movement of the light irradiation unit for explaining the document size measuring method of the image reading apparatus of the first embodiment. 6 is a flowchart illustrating an operation related to document size measurement of an image reading apparatus according to a second embodiment of the present invention. It is a top view which shows the motion of the light irradiation part for demonstrating the document size measuring method of the image reading apparatus of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an image output operation of an image forming apparatus equipped with an image reading apparatus according to an embodiment of the present invention will be described while the outline of the structure will be described with reference to FIGS. FIG. 1 is a schematic vertical sectional front view of an image forming apparatus, and FIG. 2 is a block diagram showing a configuration of the image forming apparatus. This image forming apparatus is of a color printing type in which a toner image is transferred onto a sheet using an intermediate transfer belt.

  As shown in FIG. 1, the image forming apparatus 1 includes a paper feed cassette 3 below the main body 2. The paper feed cassette 3 stores and accommodates paper P such as cut paper before printing, which is a recording medium. The sheets P are separated and sent one by one toward the upper left of the sheet feeding cassette 3 in FIG. The paper feed cassette 3 can be pulled out horizontally from the front side of the main body 2.

  A paper transport unit 4 is provided inside the main body 2 and to the left of the paper feed cassette 3. The paper transport unit 4 is formed substantially vertically along the left side surface of the main body 2. The paper transport unit 4 receives the paper P sent out from the paper feed cassette 3 and transports it to the secondary transfer unit 5 vertically upward along the left side surface of the main body 2.

  On the other hand, an image reading device 30 is mounted on the upper part of the main body 2 of the image forming apparatus 1. The image reading device 30 includes a document presser 31 further above the upper surface of the main body 2. When the user copies a document, the document holder 31 is lifted upward to place one document at a time on the contact glass 32 that appears on the upper surface of the main body 2. . Then, the image drawn on the document is read by pressing the document against the surface of the contact glass 32 with the document press 31 and scanning the light within the image reading device 30.

  Reading of a document image and start of printing are executed using an operation panel 6 provided on the front side of the image reading apparatus 30 at the top of the main body 2. Furthermore, the operation panel 6 accepts settings such as printing conditions such as the type and size of the paper P used for printing by the user, enlargement / reduction, and presence / absence of double-sided printing, and accepts an error state and cancellation of the display. It plays the role of the operation part. In addition, the operation panel 6 also serves as a notification unit for notifying the user of, for example, by displaying the state of the device, precautions, and error messages.

  Information on the image data of the document is subjected to image processing via a main control unit 17 and an image processing unit 19 which will be described later, and then sent to the exposure unit 7 disposed above the paper feed cassette 3. The exposure unit 7 irradiates the image forming unit 30 with laser light L whose power level and the like are controlled based on the image data.

  As shown in FIG. 1, there are a total of four image forming units 8 above the exposure unit 7, and an intermediate transfer belt 9 using an intermediate transfer member in the form of an endless belt above each image forming unit 8. Is provided. The intermediate transfer belt 9 is supported by being wound around a plurality of rollers, and is rotated clockwise in FIG. 1 by a driving device (not shown).

  The four image forming units 8 are of a so-called tandem system arranged in a line from the upstream side to the downstream side in the rotational direction along the rotational direction of the intermediate transfer belt 9. The four image forming units 8 are a yellow image forming unit 8Y, a magenta image forming unit 8M, a cyan image forming unit 8C, and a black image forming unit 8B in this order from the upstream side. The toner (developer) corresponding to each color is supplied to each image forming unit 8 from a toner container of each color (not shown). In the following description, the identification symbols “Y”, “M”, “C”, and “B” are omitted unless particularly limited.

  In each image forming unit 8, an electrostatic latent image of a document image is formed by the laser light L emitted from the exposure unit 7, and a toner image is developed from the electrostatic latent image. The toner image is primarily transferred onto the surface of the intermediate transfer belt 9 by a primary transfer unit 10 provided above each image forming unit 8. As the intermediate transfer belt 9 is rotated, the toner images of the respective image forming units 8 are sequentially transferred to the intermediate transfer belt 9 at a predetermined timing, whereby yellow, magenta, cyan, and black 4 are formed on the surface of the intermediate transfer belt 9. A color toner image is formed by superimposing the color toner images. Note that the image forming apparatus 1 can also form a black-only toner image for monochrome printing.

  A secondary transfer unit 5 is disposed at a position where the intermediate transfer belt 9 is suspended on the sheet conveyance path. The color toner image on the surface of the intermediate transfer belt 9 is transferred to the paper P sent in synchronization by the paper transport unit 4 at the secondary transfer nip portion formed in the secondary transfer unit 5.

  After the secondary transfer, deposits such as toner remaining on the surface of the intermediate transfer belt 9 are provided on the upstream side of the intermediate image transfer belt 9 in the rotation direction of the yellow image forming portion 8Y. 11 is cleaned and collected.

  A fixing unit 12 is provided above the secondary transfer unit 5. The paper P carrying the unfixed toner image in the secondary transfer unit 5 is sent to the fixing unit 12, and the toner image is heated and pressed by a heat roller and a pressure roller to be fixed.

  A branch portion 13 is provided above the fixing portion 12. When the double-sided printing is not performed, the paper P discharged from the fixing unit 12 is discharged from the branching unit 13 to the in-body paper discharge unit 14 provided in the upper cylinder of the image forming apparatus 1.

  The discharge port portion from which the paper P is discharged from the branch portion 13 toward the in-body paper discharge portion 14 functions as a switchback portion 15. When performing duplex printing, the switchback unit 15 switches the transport direction of the paper P discharged from the fixing unit 12. Then, the paper P passes through the branching section 13 and is sent downward through the double-sided printing paper conveyance path 16 provided on the left side of the fixing section 12 and the left side of the secondary transfer section 5. Then, it is sent to the secondary transfer unit 5.

  Further, the image forming apparatus 1 includes a main control unit 17 constituted by a CPU 18 and other electronic parts (not shown) in the main body 2 as shown in FIG. The main control unit 17 uses a central processing unit (CPU) 18 and an image processing unit 19, and the image reading device 30, the exposure unit 7, and the image forming unit 8 based on programs and data stored and input in the storage unit 20 and the like. A series of image forming operations are realized by controlling components such as the intermediate transfer belt 9 and the fixing unit 12.

  Next, an outline of the structure of the image reading device 30 of the image forming apparatus 1 will be described with reference to FIGS. 3 to 5 in addition to FIG. 2. 3 is a partially vertical front view of a model vertical section around the image reading device 30, FIG. 4 is a top view of a light irradiation unit of the image reading device 30, and FIG. 5 is a right side view of the model vertical section around the image reading device 30. . In FIG. 3, drawing of components other than the image reading device 30 of the image forming apparatus 1 is omitted, and in FIG. 4, drawing of all light sources except for a part is omitted. In FIG. 4, the lower side is the front side of the image forming apparatus 1 and the upper side is the back side of the image forming apparatus 1 with respect to the paper surface.

  In addition to the document presser 31 described above, the image reading device 30 includes a contact glass 32, a light irradiation unit 33, a scanning drive unit 40, an imaging unit 50, a reading control unit 34, and an image processing unit 35 as shown in FIGS. And an opening / closing detection device 60 which is a storage unit 36 and an opening / closing detection unit.

  The contact glass 32 is provided on the upper surface of the image reading device 30. The contact glass 32 is formed of a thin flat transparent glass and extends widely in the front-rear direction (main scanning direction) and the left-right direction (sub-scanning direction) of the image reading apparatus 30 so that the entire surface of the document D can be optically scanned at a time. It has a rectangular shape. The document is placed on the upper surface of the contact glass 32 so that the reading surface faces downward. The document D is placed with its corners aligned with reference points A (see FIG. 4) provided on the left end side and back side of the upper surface of the contact glass 32 as a reference.

  The light irradiation unit 33 is disposed immediately below the contact glass 32 so as to irradiate the reading surface of the document D, that is, the light upward. As shown in FIG. 4, a plurality of, for example, about 60 white LEDs serve as light emitting elements 33a, and the light irradiating section 33 is a straight line having substantially the same length as the contact glass 32 in the main scanning direction, which is the front-rear direction of the image reading device 30. Arranged in the shape of an elongated shape. And the light irradiation part 33 forms the block light source 33b as a light source, for example, in which five light emitting elements 33a (white LEDs) are integrated, and is composed of twelve block light sources 33b. Regarding the lighting control of the light irradiation unit 33, the reading control unit 34 controls the block light source 33b as one light source for each block light source 33b, but controls the light emitting element 33a as one light source for each light emitting element 33a. It is also possible to do. Further, the image reading apparatus 30 includes a light source light emitting circuit 37 that can adjust the light amount of the block light source 33b by changing the magnitude of the current supplied to the light emitting element 33a and the magnitude of the voltage applied to the light emitting element 33a.

  The scanning drive unit 40 is provided below the contact glass 32 and includes a first optical system unit 41 and a second optical system unit 42.

  The first optical system unit 41 of the scanning drive unit 40 supports the light irradiation unit 33 and includes a first mirror 43. The first mirror 43 receives the reflected light of the light irradiating unit 33 reflected by the reading surface of the document D, and is further set to have a predetermined inclination to change the direction substantially horizontally at an angle of 90 degrees. Has been placed. The light irradiation unit 33 and the first mirror 43 are fixed to a first optical system support member (not shown).

  The second optical system unit 42 of the scanning drive unit 40 includes a second mirror 44 and a third mirror 45. The second mirror 44 receives light reflected by the first mirror 43 of the first optical system unit 41, and is further set to have a predetermined inclination to change the direction substantially vertically downward at an angle of 90 degrees. It is arranged at almost the same height. The third mirror 45 is disposed almost directly below the second mirror 44 so as to receive the light reflected by the second mirror 44 and to change the direction substantially horizontally at an angle of 90 degrees. The second mirror 44 and the third mirror 45 are fixed to a second optical system support member (not shown).

  In addition, each mirror provided in the first optical system unit 41 and the second optical system unit 42 is configured in an elongated shape extending in the main scanning direction with substantially the same length as the contact glass 32, as in the light irradiation unit 33.

  The first optical system unit 41 and the second optical system unit 42 read in the sub-scanning direction, that is, the image in parallel with the upper surface of the contact glass 32 in order to read the image on the entire reading surface of the document D placed on the upper surface of the contact glass 32. The reader 30 can be reciprocated in the left-right direction. Therefore, the scanning drive unit 40 of the image reading apparatus 30 includes a scanning motor 46, a motor driving circuit 47 for driving the scanning motor 46, and a moving rail (not shown) extending in the left-right direction in FIG. ) And are provided. The motor drive circuit 47 is controlled based on a command from the reading control unit 34, and the light irradiation unit 33 can be moved along the rail so as to scan and read an image drawn on the entire document D. . In addition, the light irradiation part 33 moves to the location near the left end in FIG.3 and FIG.4 of the contact glass 32 before reading, and the position (home position) is hold | maintained.

  The imaging unit 50 is fixed to the lower part inside the image reading device 30. The imaging unit 50 includes an imaging lens 52 that is an optical member and a line sensor 53 that is an imaging element, on the top of a mounting base 51. Reflected light from the reading surface of the document D reflected by the third mirror 45 of the second optical system unit 42 enters the imaging lens 52. The imaging lens 52 forms an image of the reflected light on the surface of the line sensor 53 provided on the downstream side of the optical path. In this manner, the image reading apparatus 30 can read the image on the reading surface of the document D as image data using the line sensor 53.

  For example, the line sensor 53 is configured by arranging a plurality of CCDs, which are solid-state imaging elements, in a line in a straight line in the main scanning direction that is the front-rear direction of the image reading device 30, that is, the depth direction in FIG. . Each mirror of the line sensor 53, the light irradiation unit 33, and the scanning drive unit 40 extends in parallel in the main scanning direction. The line sensor 53 converts the image information (optical information) obtained by the light receiving element into an electrical signal and outputs it. The image processing unit 35 performs image processing on information obtained by scanning the reading surface of the document D in the main scanning direction by the line sensor 53 and driving the scanning driving unit 40 to scan the light irradiation unit 33 in the sub-scanning direction. By executing the above, it is possible to obtain an image of the document D as image data.

  The reading control unit 34 is configured by an electronic component such as an IC (not shown), and is a control device that controls the image reading device 30 based on a command from the main control unit 17. The reading control unit 34 drives and controls the scanning drive unit 40 according to a control command from the main control unit 17, and executes image processing based on the output from the line sensor 53 using the image processing unit 35 and outputs image data. Thus, an image reading operation is realized. Note that the image processing may be executed by the image processing unit 19 of the main body 2. Further, the image data read by the image reading device 30 in this way can be stored in the storage unit 34 or the storage unit 20 of the main body 2.

  On the other hand, the document presser 31 is provided above the contact glass 32 so as to face the contact glass 32. The document retainer 31 is a rectangular flat plate member that covers the surface of the contact glass 32. As shown in FIGS. 3 and 5, the document pressing member 31 is provided with respect to the support member 31 b around two support shafts 31 a extending substantially horizontally in the left-right direction provided at one side of the back side of the image reading device 30. It is swingably attached. As a result, the document retainer 31 can be swung up and down with respect to the contact glass 32 by swinging up and down with one side of the front side of the image reading device 30 as a free end. 3 and 5 illustrate a state in which the document presser 31 is opened.

  A white mat 31 c is provided on the surface of the document holder 31 that faces the contact glass 32 when closed. The white mat 31c has a position and a size that cover the entire surface of the contact glass 32. When the document presser 31 is closed with respect to the image reading device 30, the white mat 31c holds the document D so that it does not move so that the entire surface of the white mat 31c is pressed against the contact glass 32 uniformly.

  An opening / closing detection device 60 for the document retainer 31 is provided at an intermediate position between the two support shafts 31a of the document retainer 31 as shown in FIGS. The open / close detection device 60 includes a contact piece 61, a sensor 62, a spring 63, and a stopper 64.

  As shown in FIG. 5, the contact piece 61 is a stick-like member extending in the vertical direction, and is provided so as to be slidable in the vertical direction. The contact piece 61 includes a contact portion 61 a that contacts the document presser 31 at the upper end, and a sensor interference portion 61 b that is used for opening / closing detection by the sensor 62 at the lower end. The sensor interference part 61 b has a shape protruding toward the sensor 62.

  The sensor 62 is provided in the vicinity of the sensor interference part 61 b of the contact piece 61. The sensor 62 is configured by a transmissive optical sensor such as a photo interrupter, and includes a light emitting unit and a light receiving unit (not shown). The sensor interference part 61b of the contact piece 61 appears and disappears on the optical path between the light emitting part and the light receiving part of the sensor 62. The sensor 62 outputs an ON electrical signal when there is nothing to block the optical path between the light emitting unit and the light receiving unit, and an OFF electrical signal when the optical path is blocked. An electrical signal for ON / OFF of the sensor 62 is transmitted to the reading control unit 34 of the image reading device 30 or the main control unit 17 of the main body 2.

  The spring 63 is provided below the contact piece 61. The spring 63 is composed of a compression coil spring, and always urges the contact piece 61 upward. The stopper 64 is fixed above a portion corresponding to the sensor interference portion 61 b of the contact piece 61. Since the sensor interference portion 61b is caught by the stopper 64, the contact piece 61 does not jump out beyond the position shown in FIG. 5 due to the elastic force of the spring 63.

  Next, an operation related to the document size measurement of the image reading apparatus 30 will be described with reference to FIGS. 6 to 8 in addition to FIGS. 6 is a schematic vertical sectional right side view of the periphery of the image reading device 30 similar to FIG. 5 and shows a state in which the document presser 31 is tilted halfway. FIG. 7 relates to the document size measurement of the image reading device 30. FIG. 8 is a top view showing the movement of the light irradiation unit 33 for explaining the document size measuring method of the image reading apparatus 30.

  When the document D is placed on the contact glass 32, the document presser 31 is in an open state as shown in FIGS. At this time, the contact piece 61 of the open / close detection device 60 is urged upward by the spring 63 but is prevented from moving by the stopper 64, so the contact portion 61 a is not in contact with the document presser 31. As a result, the sensor 62 has nothing to block its optical path and is in an ON state.

  Then, after placing the document D on the contact glass 32, in the process of closing the document retainer 31, the inclination angle with respect to the surface of the contact glass 32 is tilted to a predetermined angle, for example, 30 degrees, as shown in FIG. At this time, the contact piece 61 of the open / close detection device 60 is pushed down with the document retainer 31 coming into contact with the contact portion 61a. As a result, the contact piece 61 moves downward, and the optical path of the sensor 62 is shielded by the sensor interference portion 61b of the contact piece 61 and is turned off.

  The reading control unit 34 of the image reading device 30 controls the light irradiation unit 33, the scanning drive unit 40, and the line sensor 53 based on the information of the open / close detection device 60 in which the sensor 62 is turned off, and starts measuring the document size. . The document size is measured by identifying an end portion of the document D facing the reference point A of the contact glass 32 in the main scanning direction and determining the distance between the end portion and the reference point A in the main scanning direction of the document D. The size of the document D is then measured, the end of the document D facing the reference point A in the sub-scanning direction is identified, and the size of the document D in the sub-scanning direction is measured from the distance between this end and the reference point A It is realized by doing. The reading control unit 34 moves the light irradiation unit 33 to the home position with respect to the contact glass 32 to irradiate light toward the document D, and starts identifying the end portion of the document D.

  Next, details of the size measurement of the document D will be described with reference to FIG. 8 along the flow shown in FIG. In FIG. 8, the lower side is the front side of the image forming apparatus 1 and the upper side is the back side of the image forming apparatus 1 with respect to the paper surface. Further, in FIG. 8, a plurality of light irradiation units 33 that move are described in association with each step of the flow of FIG. In FIG. 8, the lighted block light source 33b is drawn in white, and the lighted block light source 33b is shaded.

  Based on the information of the open / close detection device 60, the reading control unit 34 turns on each of the 12 block light sources 33b on condition that the document presser 31 is tilted to 30 degrees in the closing direction (start of FIG. 7). The block light sources 33b and the block light sources 33b that have been turned off are sequentially turned on or off so that they are alternately arranged along the main scanning direction, and image information is read using the line sensor 53 (step # 101). As shown in FIG. 8, the twelve block light sources 33b are controlled to be turned on, turned off, and turned on in the order from the back side of the image reading device 30 to the front side in the main scanning direction.

  With respect to the light emitted from the light irradiation unit 33, when the original D is on the upper surface of the contact glass 32, reflected light having a high intensity is obtained from the reading surface of the original D irradiated with the light. Almost no reflected light is obtained. The reflected light guided to the light receiving elements constituting the line sensor 53 is converted into a voltage of 0V to 1.5V, for example. The higher the intensity of the reflected light, that is, the higher the amount of light, the higher the voltage, and the lower the intensity of the reflected light, that is, the lower the amount of light, the lower the voltage. A threshold value is set in advance for the voltage signal obtained from the reflected light, and the image processing unit 35 processes a document with a voltage higher than the threshold value, that is, a light amount, and a document with no voltage when the voltage is lower than the threshold value, that is, a light amount is small. Based on the information from the line sensor 53 processed by the image processing unit 35, the reading control unit 34 identifies the region where the document D on the upper surface of the contact glass 32 is present and the region where it is not present.

  Next, the reading control unit 34 controls the scanning drive unit 40 to move the light irradiation unit 33 by a predetermined distance in the sub-scanning direction (step # 102). Note that this predetermined distance is an arbitrary distance that is predetermined for the movement of the light irradiation unit 33 in the sub-scanning direction in the initial stage of document size measurement. As the predetermined distance, for example, a value of 5 mm is set in advance and stored in the storage unit 20, but can be appropriately set as necessary.

  Then, the reading control unit 34 switches on and off the block light source 33b of the light irradiation unit 33, and executes reading of image information using the line sensor 53 (step # 103). As shown in FIG. 8, the twelve block light sources 33b are controlled to be turned off, turned on, and turned off in the order from the back side of the image reading device 30 to the front side in the main scanning direction. As in step # 101, the image processing unit 35 performs image processing on the presence or absence of the document D using an electrical signal obtained from the line sensor 53 that receives the reflected light for each of the lit block light sources 33b. Based on the information from the line sensor 53 processed by the image processing unit 35, the reading control unit 34 identifies the region where the document D on the upper surface of the contact glass 32 is present and the region where it is not present.

  Subsequently, based on the image information from the line sensor 53 that has received the reflected light at two locations in the sub-scanning direction of steps # 101 and # 103, the reading control unit 34 is a document facing the reference point A of the contact glass 32. The end of D in the main scanning direction is identified and confirmed (step # 104). The reading control unit 34 combines the region where the document D exists on the upper surface of the contact glass 32 and the region where the document D does not exist at two locations in the sub-scanning direction of steps # 101 and # 103, thereby combining the end portions of the document D in the main scanning direction. Is identified and confirmed.

  Subsequently, the reading control unit 34 measures the size of the document D in the main scanning direction from the distance between the end of the document D in the main scanning direction and the reference point A (step # 105). More specifically, the reading control unit 34 measures the size of the document D in the main scanning direction from the number of dots from the reference point A to the position of the end in the main scanning direction × the pitch per dot in the image data.

  When the size measurement of the document D in the main scanning direction is completed, the reading control unit 34 turns on one block light source 33b located in the region where the document D exists with respect to the end in the main scanning direction (step # 106). The single block light source 33b that is lit is located in an area inside the document D drawn by a two-dot chain line in FIG.

  Subsequently, in a state in which one block light source 33b located in the area where the document D exists is lit, the reading control unit 34 controls the scanning driving unit 40 to move the light irradiation unit 33 in the sub-scanning direction (step). In step # 107, image information is read using the line sensor 53 (step # 108). Then, the reading control unit 34 determines whether or not the document D is present based on the image information from the line sensor 53 that has received the reflected light with respect to the single block light source 33b that is turned on (step # 109). .

  When the presence of the document D is detected with respect to the single block light source 33b that is turned on, that is, when it is determined that the document D is not the end of the document D (No in Step # 109), the reading control unit 34 continues. Is moved in the sub-scanning direction (step # 107), and the step of reading image information using the line sensor 53 (step # 108) is repeated. For the movement of the light irradiation unit 33 in the sub-scanning direction in step # 107, for example, a moving distance such as 5 mm or 10 mm is preset, and reading by the line sensor 53 in step # 108 and original in # 109 are performed for each moving distance. Identification of the end of D may be performed.

  When it is determined that the document D does not exist for one block light source 33b lit in step # 109, that is, it is the end of the document D (Yes in step # 109), the reading control unit 34 determines the contact glass 32. The end of the document D facing the reference point A in the sub-scanning direction is determined (step # 110). At this time, the light irradiation unit 33 is located outside the region where the document D exists in the sub-scanning direction as shown in FIG.

  Subsequently, the reading control unit 34 measures the size of the document D in the sub-scanning direction from the distance between the end of the document D in the sub-scanning direction and the reference point A (step # 111). More specifically, the reading control unit 34 measures the size of the document D in the sub-scanning direction from the number of dots from the reference point A to the position of the edge in the sub-scanning direction × the pitch per dot in the image data. Then, the reading control unit 34 ends the operation flow relating to the document size measurement (END in FIG. 7).

  As described above, the reading control unit 34 of the image reading apparatus 30 moves the light irradiation unit 33 in the sub-scanning direction, and individually turns on or sequentially turns on each of the plurality of block light sources 33b of the light irradiation unit 33 in the main scanning direction. Based on the information from the line sensor 53 that is turned off and receives the reflected light, the end portion of the document D facing the reference point A of the contact glass 32 in the main scanning direction is identified, and the end portion and the reference point A are identified. The size of the document D in the main scanning direction is measured from the distance between them, and then the end of the document D facing the reference point A in the sub-scanning direction is identified and the distance between this end and the reference point A is determined. The size of the document D in the sub-scanning direction is measured. In other words, the image forming apparatus 1 turns on and off each of the plurality of block light sources 33b arranged in the main scanning direction in turn, while turning the end of the document D in the main scanning direction and the end of the sub scanning direction. Perform part identification. As a result, it is possible to relatively reduce the number of light sources that are lit in the region outside the edge of the document D when measuring the document size. Therefore, it is possible to prevent the user from being dazzled when measuring the document size, and it is possible to easily and automatically perform measurement of an irregular document size.

  Then, in the initial stage of moving the light irradiation unit 33 in the sub-scanning direction, the reading control unit 34 alternately turns on the block light sources 33b that are turned on and the block light sources 33b that are turned off along the main scanning direction. Are sequentially turned on or off so as to be lined up, and then the light irradiation unit 33 is moved 5 mm in the sub-scanning direction, and then the block light source 33b is turned on and off to receive reflected light at two locations in the sub-scanning direction. Based on the information from the line sensor 53, the end of the document D in the main scanning direction is identified. Further, the reading control unit 34 continues to move the light irradiation unit 33 in the sub-scanning direction with one of the block light sources 33b located in the region where the document D exists with respect to the end in the main scanning direction. Based on the information from the line sensor 53 that has received the reflected light, the end of the document D in the sub-scanning direction is identified. Thus, when identifying the end of the document D in the main scanning direction, only about half the block light source 33b of the light irradiation unit 33 is lit. Further, the block light source 33b is not turned on in an area outside the edge of the document D in the main scanning direction except for a short period until the edge of the document D in the main scanning direction is identified. Therefore, it is possible to further suppress the user's dazzling feeling when measuring the document size.

  In the above embodiment, when identifying the end portion of the document D in the main scanning direction, the identification is performed based on information from the line sensors 53 at two locations in the sub scanning direction in which the block light source 33b is turned on and off. However, it may be identified based on information of three or more locations.

  In addition, the light irradiation unit 33 is formed by integrating a plurality of light emitting elements 33a to form one block light source 33b, and is configured by a plurality of block light sources 33b. The reading control unit 34 turns on or off the light emitting elements 33a for each block light source 33b. Therefore, the time required for measuring the document size is relatively short. Therefore, it is possible to more easily measure the document size.

  Further, the reading control unit 34 has an angle of 30 degrees with respect to the upper surface of the contact glass 32 when the document holder 31 opened based on information from the opening / closing detection device 60 for detecting the opening / closing operation of the document holder 31 is directed in the closing direction. Since the measurement of the size of the document D in the main scanning direction and the size measurement of the document D in the sub-scanning direction are started, the document presser 31 is automatically tilted from the open state to the closing direction and automatically scanned. Size measurement starts. Since document size measurement is started with the document retainer 31 opened to some extent, it is possible to easily identify the end of the document D.

  According to the configuration of the above embodiment, when measuring the document size, each of the plurality of block light sources 33b of the light irradiation unit 33 is individually turned on or off sequentially in the main scanning direction. Can be easily measured. Further, since the number of block light sources 33b that are lit in an area outside the edge of the document D is relatively small, it is possible to prevent light from leaking from the outside of the document D to the user side. Therefore, it is possible to prevent the user from being dazzled when measuring the document size, and to improve the work efficiency that can easily and automatically perform the measurement of the irregular document size. The image reading device 30 can be provided. Further, it is possible to provide the image forming apparatus 1 equipped with such an image reading device 30.

  Next, an image reading apparatus according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a flowchart showing an operation related to the document size measurement of the image reading apparatus, and FIG. 10 is a top view showing the movement of the light irradiation unit for explaining the document size measurement method of the image reading apparatus. Since the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 1 to 8, the same reference numerals are given to the configurations common to the first embodiment and Description and explanation thereof will be omitted.

  The image reading apparatus 30 according to the second embodiment performs size measurement of the document D according to the following flow.

  Based on the information of the open / close detection device 60, on the condition that the document presser 31 is tilted up to 30 degrees in the closing direction (start of FIG. 9), the reading control unit 34 performs main scanning among the 12 block light sources 33b. The block light sources 33b at both ends in the direction are turned on, and image information is read using the line sensor 53 (step # 201). As for the two block light sources 33b, as shown in FIG. 10, one place on the back side and one place on the front side of the image reading device 30 are respectively lit.

  Subsequently, the reading control unit 34 applies the two block light sources 33b that are lit on the upper surface of the contact glass 32 corresponding to the two block light sources 33b based on information from the line sensor 53 that has received the reflected light. It is determined whether or not the document D exists at each location (step # 202). For example, in the initial stage of document size measurement, as shown in FIG. 10, the light irradiation unit 33 is located at a position corresponding to the left end of the contact glass 32, so the document D is located at the block light source 33 b on the back side of the document reading device 30. And the document D is not detected at the block light source 33b on the front side.

  When the presence of the document D is not detected for any one of the two block light sources 33b that are lit (No in Step # 202), the reading control unit 34 controls the scanning drive unit 40 to perform sub-scanning on the light irradiation unit 33. The direction is moved (step # 203). Further, the reading control unit 34 moves the two block light sources 33b to be turned on from both ends in the main scanning direction by one block each toward the other end, and executes reading of image information using the line sensor 53 ( Step # 204). At this time, as shown in FIG. 10, the two block light sources 33b that are lit are moved to the second locations counted from both ends in the main scanning direction.

  And the reading control part 34 is the location of the upper surface of the contact glass 32 corresponding to two block light sources 33b based on the information from the line sensor 53 which received those reflected light with respect to the two block light sources 33b lighted. It is determined again whether or not each document D exists (step # 202).

  When the presence of the document D is not detected for any one of the two block light sources 33b that are lit (No in Step # 202), the reading control unit 34 continues to move the light irradiation unit 33 in the sub-scanning direction (Step S202). Step # 203) repeats the step of moving the block light source 33b to be turned on and reading the image information using the line sensor 53 (Step # 204).

  Note that in detail regarding the movement of the light irradiation unit 33 in the sub-scanning direction in step # 203, a movement distance such as 30 mm or 40 mm is set in advance, and the block light source 33b to be lit in step # 204 is set for each movement distance. The movement and reading by the line sensor 53 are performed, and the edge of the document D is identified in step # 202. During the movement in the sub-scanning direction such as 30 mm or 40 mm, the block light source 33b to be lit is kept in the same place without moving in the main scanning direction, and for example, a line for each moving distance in the sub-scanning direction such as 5 mm or 10 mm. Reading by the sensor 53 and identification of the edge of the document D are executed.

  When the presence of the document D is detected for both of the two block light sources 33b that are lit in step # 202 (Yes in step # 202), the reading control unit 34 scans the document D facing the reference point A of the contact glass 32. The end in the main scanning direction is determined (step # 205). At this time, as shown in FIG. 10, the two block light sources 33b that are lit are both located inside the area where the document D exists in the main scanning direction.

  Subsequently, the reading control unit 34 measures the size of the document D in the main scanning direction from the distance between the end of the document D in the main scanning direction and the reference point A (step # 206). More specifically, the reading control unit 34 measures the size of the document D in the main scanning direction from the number of dots from the reference point A to the position of the end in the main scanning direction × the pitch per dot in the image data.

  Next, the reading control unit 34 controls the scanning drive unit 40 to move the light irradiation unit 33 in the sub-scanning direction (step # 207). Further, the reading control unit 34 moves the two block light sources 33b that are sequentially turned on from both ends in the main scanning direction by one block each toward the other end, and reads the image information using the line sensor 53. (Step # 208). And the reading control part 34 is the location of the upper surface of the contact glass 32 corresponding to two block light sources 33b based on the information from the line sensor 53 which received those reflected light with respect to the two block light sources 33b lighted. It is determined whether or not each document D exists (step # 209).

  When the presence of the document D is detected for one of the two block light sources 33b that are lit (Yes in Step # 209), the reading control unit 34 continues to move the light irradiation unit 33 in the sub-scanning direction. (Step # 207), the step of executing the movement of the block light source 33b to be lit and the reading of the image information using the line sensor 53 (Step # 208) is repeated.

  Note that in detail regarding the movement of the light irradiation unit 33 in the sub-scanning direction in step # 207, as in step # 203, a movement distance such as 30 mm or 40 mm is preset, and the step is performed for each movement distance. The block light source 33b to be turned on in # 208 is moved and read by the line sensor 53, and the edge of the document D is identified in step # 209. During the movement in the sub-scanning direction such as 30 mm or 40 mm, the block light source 33b to be lit is kept in the same place without moving in the main scanning direction, and for example, a line for each moving distance in the sub-scanning direction such as 5 mm or 10 mm. Reading by the sensor 53 and identification of the edge of the document D are executed.

  When the presence of the document D is not detected for both of the two block light sources 33b lit in step # 209 (No in step # 209), the reading control unit 34 scans the document D facing the reference point A of the contact glass 32. An end in the sub-scanning direction is determined (step # 210). At this time, the light irradiation unit 33 is located outside the region where the document D exists in the sub-scanning direction as shown in FIG.

  Subsequently, the reading control unit 34 measures the size of the document D in the sub-scanning direction from the distance between the end of the document D in the sub-scanning direction and the reference point A (step # 211). More specifically, the reading control unit 34 measures the size of the document D in the sub-scanning direction from the number of dots from the reference point A to the position of the edge in the sub-scanning direction × the pitch per dot in the image data. Then, the reading control unit 34 ends the operation flow relating to the document size measurement (END in FIG. 9).

  As described above, the reading control unit 34 turns on the block light sources 33b at both ends in the main scanning direction at the initial stage of moving the light irradiation unit 33 in the sub scanning direction, and then moves the light irradiation unit 33 in the sub scanning direction. The main scanning of the document D is based on information from the line sensor 53 that receives the reflected light when the block light sources 33b are turned on one by one from the both ends in the main scanning direction toward the other end in the main scanning direction. Identify the end in the direction and the end in the sub-scanning direction. Thereby, only one block light source 33b is required to be lit in an area outside the edge of the document D when measuring the document size. Therefore, it is possible to further suppress the user from being dazzled when measuring the document size.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, the image forming apparatus 1 equipped with the image reading apparatus 30 according to the above-described embodiment of the present invention is an image forming apparatus for color printing that transfers a toner image onto a sheet using an intermediate transfer belt. The image forming apparatus is not limited to such a type, and may be an image forming apparatus that does not use an intermediate transfer belt or an image forming apparatus for black and white printing.

  In the above embodiment, when measuring the document size, the light irradiation unit 33 is controlled to be turned on for each block light source 33b that is a light source to identify the end of the document D. However, the document size measurement method is limited to this. However, the end of the document D may be identified by turning on and off the single light emitting element 33a as a light source as a control unit.

  The start timing of the document size measurement by the document reading device 30 is limited to the condition that the document holder 31 is tilted to a predetermined angle (for example, 30 degrees with respect to the surface of the contact glass 32) in the closing direction. I don't mean. For example, the document size measurement may be performed with the document retainer 31 opened, or the document size measurement may be performed at the beginning of closing the document retainer 31 in the opened state. Even when the document size measurement is executed with the document retainer 31 opened as described above, since the block light sources 33b that are lit in the area outside the edge of the document D are relatively few, the user feels dazzled. It is possible to suppress this.

  The present invention can be used in general image reading apparatuses used for copying machines, image scanners, and the like.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 6 Operation panel 17 Main control part 30 Image reading apparatus 31 Document holding | pressing 32 Contact glass (original platen)
33 Light irradiation part 33a Light emitting element 33b Block light source (light source)
34 Reading control unit (control unit)
35 Image processing unit 36 Storage unit 40 Scanning drive unit 50 Imaging unit 53 Line sensor (imaging device)
60 Open / close detection device

Claims (3)

A document table on which a document is placed on the upper surface and a reference point is provided for placing the document so that the corners of the document are aligned;
A document presser that is openable and closable with respect to the document table;
An open / close detection unit for detecting an opening / closing operation of the document press and detecting that an inclination angle of the document press with respect to a surface of the document table has fallen to a predetermined angle in a process of closing the document press ;
A light irradiating unit that is disposed below the document table and includes a plurality of light sources including one or a plurality of light emitting elements, and the light sources are linearly arranged in a main scanning direction to irradiate light toward the document;
A scanning drive unit for moving the light irradiation unit in a sub-scanning direction perpendicular to the main scanning direction;
An image sensor that receives reflected light that is irradiated from the light irradiation unit and reflected from the surface of the document;
A control unit for measuring the size of the size and the sub-scanning direction in the main scanning direction of the document based on information from the imaging device,
With
The control unit detects that the document presser is in the closing direction when the open / close detection unit detects that the inclination angle of the document press with respect to the surface of the document table has fallen to a predetermined angle in the process of closing the document presser. It is determined that the light source has been tilted to a predetermined angle, and on this condition, the light source that turns on each of the light sources of the light irradiation unit and the light source that is turned off are alternately along the main scanning direction. After turning on or off sequentially so as to line up, reading image information using the image sensor is performed, and then controlling the scanning drive unit to move the light irradiation unit by a predetermined distance in the sub-scanning direction. Reading of image information using the image sensor is performed by switching between turning on and off each of the plurality of light sources, and the base is based on image information from the image sensor at these two locations. It measures the main scanning direction size of the document from the distance between the identifying the end of the main scanning direction of the document opposite to the point with the end portion and the reference point, followed the document exists area Whether the original exists based on the image information from the image sensor by controlling the scanning drive unit with the light source located in the position on and moving the light irradiation unit a predetermined distance in the sub-scanning direction If the presence of the original is detected and it is determined that the original is not an end portion of the original, the light irradiation unit is moved a predetermined distance in the sub-scanning direction to obtain image information from the image sensor. Whether or not the original exists, and if it is determined that the original does not exist and is an end of the original, an end in the sub-scanning direction of the original facing the reference point is identified. the original Te from the distance between the reference point and the end Image reading apparatus according to claim Rukoto which to measure the total sub-scanning direction size of the. A document table on which a document is placed on the upper surface and a reference point is provided for placing the document so that the corners of the document are aligned;
A document presser that is openable and closable with respect to the document table;
An open / close detection unit for detecting an opening / closing operation of the document press and detecting that an inclination angle of the document press with respect to a surface of the document table has fallen to a predetermined angle in a process of closing the document press ;
A light irradiating unit that is disposed below the document table and includes a plurality of light sources including one or a plurality of light emitting elements, and the light sources are linearly arranged in a main scanning direction to irradiate light toward the document;
A scanning drive unit for moving the light irradiation unit in a sub-scanning direction perpendicular to the main scanning direction;
An image sensor that receives reflected light that is irradiated from the light irradiation unit and reflected from the surface of the document;
A control unit for measuring the size of the size and the sub-scanning direction in the main scanning direction of the document based on information from the imaging device,
With
The control unit detects that the document presser is in the closing direction when the open / close detection unit detects that the inclination angle of the document press with respect to the surface of the document table has fallen to a predetermined angle in the process of closing the document presser. Subject to this as well as determined that the brought down to a predetermined angle towards, using the imaging device after each lit the light source at both ends of the main scanning direction among the plurality of light sources of the light irradiation unit Reading of image information is performed to determine whether or not the document exists based on the image information, and it is determined that the presence of the document is not detected for one of the two light sources that are lit. Subsequently, the scanning drive unit is controlled to move the light irradiation unit by a predetermined distance in the sub-scanning direction, and the light source to be turned on among the plurality of light sources of the light irradiation unit is mainly used. It is determined whether or not the original exists for the two light sources that are moved one by one in order from each end portion in the scanning direction and turned on based on image information from the image sensor. When it is determined that the presence of the original is detected for both of the two light sources that are lit, the edge of the original in the main scanning direction facing the reference point based on the image information from the image sensor at this time And determining the size of the original in the main scanning direction from the distance between the edge and the reference point, and then controlling the scan driving unit to set the light irradiation unit in the sub-scanning direction. The light source to be turned on among the plurality of light sources of the light irradiation unit is moved one by one from the both end portions at the beginning of movement in the main scanning direction toward the other end in order to move the distance from the image sensor. Previous based on image information It is determined whether or not a document exists, and when the presence of the document is detected and it is determined that the document is not an end portion of the document, the light irradiation unit is moved a predetermined distance in the sub-scanning direction and the light irradiation is continued. Whether the original is present based on image information from the imaging device by moving one of the plurality of light sources to be turned on one by one from the both ends in the main scanning direction toward the other end If the document does not exist and it is determined that the document is an end portion of the document, an end portion in the sub-scanning direction of the document facing the reference point is determined, and the end portion and the reference point are determined. image reading apparatus according to claim Rukoto which to measure total sub-scanning direction size of the document from the distance between the.   An image forming apparatus comprising the image reading apparatus according to claim 1.

Images