JP2006311316A - Image reading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means capable of obtaining the excellent read image even if ambient light has an adverse effect on the means when a light source is regulated in light volume in an image reading device which reads in images through a process of irradiating a manuscript with light emitted from a light source. <P>SOLUTION: The control unit 55 of a compound machine 1 sets the previously set light volume value equal to the volume value of light emitted from the light source 42 of a CIS unit 40 when the image is read in a case where the opened position of a manuscript pressing cover 6 is detected. Therefore, an image reading process can be carried out through the CIS unit 40 without using an adjusted light volume value affected by ambient light L when the manuscript pressing cover 6 is kept in an opened position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that reads an image by irradiating a document with light through a transmission member of a document table, and more particularly to an image reading apparatus that adjusts the amount of light irradiated from a light source with respect to a reference member. Is.

  Conventionally, as an image reading apparatus mounted on a copier, a scanner, or a multi-function apparatus having both of these functions, a flat bed scanner or an ADF (Auto Document) that transports a document from a paper feed tray to a paper discharge tray via a transport path. It is known that an automatic document transport mechanism called “Feeder” is equipped with an image reading means such as a CCD (Charge Coupled Device) or CIS (Contact Image Sensor) at a predetermined position to read an image of a document being transported. Yes.

  For example, in a conventional image reading apparatus 90 as shown in FIG. 11, the ADF 92 is provided in the document pressing cover 91, and the document on the sheet feeding tray is conveyed to the ADF reading area 93 </ b> A of the platen glass 93 by the ADF 92. An image of a document passing over the ADF reading area 93A can be read by an image scanner (not shown) disposed in the document table 94. The image reading device 90 can also be used as a flatbed scanner. The document placed on the stationary document reading area 93B of the platen glass 93 is fixed by closing the document pressing cover 91 and fixing the document. An image of the original can be read by an image scanner disposed inside the document.

  The CCD or CIS used as the image sensor emits light from a light source toward the platen glass 93, the light passes through the platen glass 93 and is reflected by the surface of the document, and the reflected light is converted into an electric signal by a light receiving element. The image of the original is optically read by converting to. Since the light source and light receiving element of such an image sensor have variations in light amount, uneven light distribution, and uneven sensitivity, after adjusting the light amount of the light source with respect to the white reference member, the reference member is read to So-called shading correction is performed in which level data and black level data are acquired and read data is corrected based on the white level data and black level data. For example, in the image reading apparatus 90, a reference member is disposed on the back side of the partition member 95 that partitions the platen glass 93 into an ADF reading area 93A and a stationary document reading area 93B, and prior to reading an image of a document. The light quantity adjustment and reference data acquisition are performed on the reference member.

  By the way, in recent years, it is possible to use a light source with low illuminance as the sensitivity of the image sensor is improved. For example, in CIS, an LED (Light Emitting Diode) light source, or a LIDE using an LED and a linear light guide. A light source is used. There is a problem that the influence of external light on the reference member is increased by reducing the illuminance of the light source. External light refers to a case where the image reading device 90 places an original on the stationary original reading area 93B of the platen glass 93 and reads an image with an image scanner with the original pressing cover 91 open as shown in the figure. In addition, it is indoor or outdoor light that enters the document table 94 from the ADF reading area 93A or the like.

  Such external light does not enter the document table 94 because the entire platen glass 93 is covered when the document pressing cover 91 is closed, but for example, when reading an image of a thick book document. In other words, the document pressing cover 91 cannot be completely closed, and external light may enter the document table 94. Further, when reading a large document, there is a case where the image is read without closing the document pressing cover 91 in order to confirm the reading position. 94 may enter.

  If the illuminance of the light source is sufficiently large with respect to the external light, the reflected light from the reference member also becomes sufficiently large. Therefore, even if a slight amount of external light is added to the reflected light, the effect of the read image Does not appear as significant degradation. However, as the illuminance of the light source decreases, the reflected light also decreases, so the ratio of external light added to the reflected light increases. For example, if external light affects the light amount adjustment, the light source of the image sensor is adjusted to a light amount that is smaller by the amount of external light. Therefore, the amount of light emitted from the light source to the document is also reduced, causing a problem that the read image becomes dark. In particular, when the image sensor is scanned with respect to a document placed on the stationary document reading area 93B, the influence of external light becomes smaller as the distance from the ADF reading area 93A increases, and image degradation is significant. In order to deal with such a problem, for example, a means for preventing light from entering the light receiving element of the image sensor by providing light shielding plates on both sides of the image sensor has been proposed (see Patent Document 1).

JP 2003-134307 A

  By providing a shielding plate in the image sensor, for example, external light entering from the side of the image sensor can be blocked, but external light entering the thickness of the platen glass 93 cannot be blocked. In particular, when a sufficient width cannot be set for the partition member 95 due to a request for downsizing of the apparatus, or when the platen glass 93 is formed of a single glass plate, the output of the image sensor with respect to the reference member. There is a problem that external light influences the adjustment.

  The present invention has been made in view of such a problem. In an image reading apparatus that reads an image by irradiating light from a light source to a document, the image reading apparatus is good even when it is affected by external light in adjusting the light amount of the light source. It is an object of the present invention to provide a means capable of obtaining a read image.

  The present invention provides a document placing table having a transmissive member for placing a document, a document pressing member provided on the document placing table so as to be openable and closable so as to cover the transmissive member, and irradiating the document from a light source. And an image reading means for reading an image recorded on the original based on the reflected light, and disposed on the opposite side to the original placement surface of the transmission member, and the image reading means is mounted along the transmission member. Scanning means for reciprocating in a predetermined direction, opening / closing detecting means for detecting opening / closing of the document pressing member, control means for controlling image reading of the image reading means and reciprocating movement of the scanning means, and the transmitting member. An image reading apparatus provided in a region exposed as an outer surface of the document placing table and serving as a lightness reference for the image reading means, wherein the control means includes the open / close detection means Is the above document When even detects the open state of the members, it is an amount value of the light emitted from the light source when the image reading a predetermined light amount set value.

  By closing the document pressing member with respect to the document placement table, the document placed on the transmission member is pressed against the transmission member and the transmission member is covered. This prevents external light from entering the inside of the document table. Then, the control unit operates the scanning unit and the image reading unit to read the image of the original. Prior to this image reading, the control means adjusts the light amount of the light source of the image reading means. When the document pressing member is closed with respect to the document placing table, that is, when the open / close detection means detects the closed position of the document pressing member, the control means adjusts the amount of light with respect to the reference member. Then, based on the obtained light quantity adjustment value, the image is read by irradiating light from the light source of the image reading means. On the other hand, when the document pressing member is open with respect to the document placement table, external light enters the document placement table, and the external light also affects the reference member. Therefore, when the document pressing member is opened with respect to the document placing table, that is, when the open / close detection unit detects the opening posture of the document pressing member, the control unit is not concerned with the obtained light amount adjustment value. First, image reading is performed by irradiating light from the light source of the image reading unit with a predetermined light amount setting value as a light amount value.

  According to the present invention, in the image reading apparatus, the control unit uses a predetermined light amount value set in advance as the light amount setting value.

  Such a light amount setting value may be set, for example, at the time of manufacturing or shipping the image reading apparatus. As the light amount setting value, a light amount adjustment value obtained by adjusting the light amount when the document pressing member is closed can be used.

  In the image reading apparatus according to the aspect of the invention, the control unit may include a light amount of a light source of the image reading unit with respect to the reference member when the open / close detection unit detects a closed posture of the document pressing member. The light amount adjustment value obtained by the adjustment is stored, and the light amount adjustment value is used as the light amount setting value.

  As such a light amount setting value, for example, the light amount adjustment value obtained in the image reading that has already been performed, or when the power is turned on when the document cover is closed, the light amount adjustment is performed separately from the image reading by the image reading unit. The light amount adjustment value obtained by performing the above can be used.

  Further, according to the present invention, in the image reading apparatus, the opening / closing detection means detects the opening / closing of the document pressing member by detecting the presence / absence of external light entering the document table.

  Such detection of the presence / absence of external light can be performed using an image reading unit, so that it is not necessary to separately provide a sensor for detecting the opening / closing of the document pressing member, which reduces the size and cost of the apparatus. Realized.

  According to the present invention, in the image reading apparatus, the open / close detection unit is configured such that when the light amount adjustment value obtained by the image reading unit performing light amount adjustment on the reference member is outside a predetermined range, The holding member detects the open posture.

  When the document pressing member is opened with respect to the document mounting table, external light enters the document mounting table, and the external light also affects the reference member. When the light amount adjustment of the light source of the image reading unit is performed on the reference member, the obtained light amount adjustment value becomes smaller than the light amount adjustment value when the document pressing member is closed. Therefore, if the obtained light amount adjustment value is outside the predetermined range, it can be detected that the document pressing member is open to the extent that external light enters the document table. Further, the predetermined range can be determined based on the light amount setting value, for example.

  According to the present invention, in the image reading apparatus, the open / close detection means is a document pressing member when the read value when the image reading means turns off the light source and reads the reference member is out of a predetermined range. Is detected as an open posture.

  When the document pressing member is opened with respect to the document mounting table, external light enters the document mounting table, and the external light also affects the reference member. When the light source is turned off with respect to the reference member and the lightness reference of the image reading means is acquired, that is, when the black level reference is acquired, the obtained reading value is out of the reading value when the document pressing member is closed. It grows by the amount of light. Therefore, if the obtained reading value is outside the predetermined range, it can be detected that the document pressing member is open to the extent that external light enters the document table. The predetermined range can be determined based on, for example, a black level reference signal output from a device used as an image reading unit.

  According to the present invention, in the image reading apparatus, the reference member is provided with a white portion and a black portion in the moving direction of the scanning unit, and the open / close detection unit includes the image reading unit as a light source. Is turned off and the document pressing member detects the open position when the difference between the read values when the white portion and the black portion of the reference member are read is a predetermined threshold value or more.

  When the document pressing member is opened with respect to the document mounting table, external light enters the document mounting table, and the external light also affects the reference member. The light source is turned off with respect to the reference member, and the white portion and the black portion of the reference member are read. When the document pressing member is closed, these read values are the same. However, when the external light influences, the read values differ due to the difference in the reflectance of the external light. Therefore, if the difference between the obtained reading values is equal to or greater than a predetermined threshold, it can be detected that the document pressing member is open to the extent that external light enters the document table.

  According to the present invention, in the image reading apparatus, the control unit applies a light amount adjustment value obtained by adjusting a light amount of a light source of the image reading unit to the reference member. Then, the lightness reference of the image reading means is obtained by irradiating light from the light source.

  When the document holding member is open with respect to the document table, external light enters the document table and the external light also affects the reference member. Are performed on the same reference member, the influence of external light is also the same. Therefore, by obtaining the lightness reference of the image reading unit for the same reference member by the actual light amount adjustment value performed on the reference member affected by the external light, the appropriate light amount considering the external light is obtained. The brightness standard can be acquired.

  According to the present invention, in the image reading apparatus, the reference member includes the transmissive member, and a partition member that divides the region by disposing the transmissive member in a region exposed as an outer surface of the document table. Preferably, the image reading means reads the image of the document conveyed in a predetermined direction in the area where the transmission member is exposed as the outer surface of the document table. The transported document reading area and the image reading means divide into a stationary document reading area for reading an image of the document placed on the transmission member.

  Accordingly, it is not necessary to secure a space for arranging the reference member in a region other than the region where the transmission member is exposed as the outer surface of the document placing table, and the document placing table can be downsized.

  According to the present invention, in the image reading apparatus, the pressing member is provided with an automatic document transport mechanism that transports the document loaded in the paper feed tray to the transported document reading area and discharges the document to the discharge tray. The partition member is formed with a guide surface for guiding the document before reading to the transported document reading area on the surface on the pressing member side.

  By providing a guide surface on the partition member, it is possible to smoothly transport the document to the transported document reading region, and it is possible to reduce the size and cost of the apparatus by using the common member. Further, since the guide surface guides the document before reading to the transported document reading area, the lowermost part of the guide surface does not need to be recessed from the document placing surface of the transmitting member. Therefore, the transmissive member can be constituted by a single member extending over the transported document reading area and the stationary document reading area.

  According to the present invention, in the image reading apparatus, the image reading means is a contact image sensor. In a contact image sensor, a light source with a low illuminance such as a light emitting diode is often used as a light source, and when a light source with a low illuminance is used, it is easily affected by external light. Therefore, when the image reading means is a contact image sensor, the above-described operation and effect appear more remarkably.

  According to the image reading apparatus of the present invention, when the document pressing member is closed with respect to the document placing table, the control unit adjusts the light amount with respect to the reference member and sets the obtained light amount adjustment value. Based on this, the image is read by irradiating light from the light source of the image reading means, and when the document pressing member is opened with respect to the document placing table, the control means uses the predetermined light amount setting value as the light amount value. Since the image reading is performed by irradiating light from the light source of the reading unit, the image reading unit can read the image without using the light amount adjustment value affected by the external light when the document pressing member is in the open position. It can be carried out. Thereby, it is possible to prevent deterioration of the read image such as the read image becoming dark or blurred.

  Embodiments of the present invention will be described below with reference to the drawings as appropriate. In addition, this embodiment is only an example of this invention, and it cannot be overemphasized that embodiment can be changed suitably in the range which does not change the summary of this invention.

  FIG. 1 shows an external configuration of a multifunction machine 1 according to an embodiment of the present invention. The multi-function device 1 is a multi-function device (MFD: Multi Function Device) that integrally includes a scanner function, a printer function, and a facsimile function. The upper part of the multifunction device 1 is a scanner unit 2 for reading an image of a document, and the lower part of the multifunction device 1 is a printer unit 3 for recording an image on a recording sheet. The image reading apparatus according to the present invention is realized as the scanner unit 2 of the multifunction machine 1, and the printer function or the like is an arbitrary mechanism in the present invention. For example, the image reading apparatus according to the present invention as a single scanner having only the scanner function. An apparatus may be realized.

Hereinafter, the configuration of the scanner unit 2 will be described in detail. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 and shows a main configuration of the ADF 5.
As shown in FIGS. 1 and 2, the scanner unit 2 has an auto document feeder (ADF) 5 that is an automatic document feeder mechanism with respect to a document placing table 4 that functions as an FBS (Flatbed Scanner). A document pressing cover 6 (document pressing member) provided with is attached to be freely opened and closed via a hinge on the back side. The document table 4 is configured as a housing of the multifunction machine 1, and a platen glass 20 (transparent member) is disposed on the top surface facing the document pressing cover 6. When the document pressing cover 6 is opened, the platen glass 20 is exposed as the upper surface of the document placing table 4, and when the document pressing cover 6 is closed, the entire upper surface of the document placing table 4 including the platen glass 20 is covered. Is called. An image reading unit 21 is built in the document table 4 so as to face the platen glass 20.

  The document pressing cover 6 is provided with an ADF 5 that continuously conveys documents from the paper feed tray 22 to the paper discharge tray 23 via a predetermined conveyance path 26. In the conveyance process by the ADF 5, the document passes over the platen glass 20, and the image reading unit 21 reads the image of the document below the platen glass 20. Details of the structure of the ADF 5 will be described later. In addition, a pressing member 19 made of a sponge, a white plate, or the like is disposed on the lower surface of the document pressing cover 6 in order to press the document placed on the platen glass 20.

  An operation panel 7 is provided on the front side of the document table 4. The operation panel 7 includes various operation buttons and a liquid crystal display unit, and the multifunction device 1 operates according to instructions from the operation panel 7. In addition to the instruction from the operation panel 7, the multifunction device 1 also operates according to an instruction connected to the computer and transmitted from the computer via a printer driver, a scanner driver, or the like.

  In addition, a slot portion 8 into which various small memory cards as recording media can be loaded is provided in the upper left part of the front surface of the multifunction device 1. The image data recorded in the small memory card loaded in the slot unit 8 is read out, information about the image data is displayed on the liquid crystal display unit, and an input for recording an arbitrary image on the recording sheet by the printer unit 3 is performed. This can be done from the operation panel 7.

  As shown in FIGS. 1 and 2, the document pressing cover 6 is provided with a paper feed tray 22 and a paper discharge tray 23 in two upper and lower stages. The paper feed tray 22 is formed integrally with the upper surface of the document pressing cover 6. A document whose image is read by the ADF 5 is placed on the paper feed tray 22 so that a plurality of sheets are stacked and the front end in the paper feed direction is inserted into the ADF 5. In addition, a pair of document guides 24 are provided on the paper feed tray 22 so as to be slidable in the depth direction across the depth direction of the multifunction machine 1. The document guide 24 stands up from the sheet feed tray 22 and guides both ends in the width direction of the document placed on the sheet feed tray 22, and either one of a pair of documents by a well-known interlocking mechanism. When the guide 24 is slid, the other document guide 24 is also slid in the opposite direction.

  That is, when the document width is narrow, if one document guide 24 on the front side of the multifunction machine 1 is slid to the back side, the other document guide 24 on the back side slides to the front side in conjunction with this. Moving. As a result, the width of the document guided by the pair of document guides 24 can be reduced with the approximate center in the depth direction as the center. On the contrary, when the document width is wide, when one document guide 24 on the front side of the multifunction machine 1 is slid and moved to the front side, the other document guide 24 on the back side is linked to the back side. By sliding, the width of the document guided by the pair of document guides 24 can be increased.

  A paper discharge tray 23 is integrally formed with the pair of document guides 24 so as to be separated from the paper feed tray 22 in the vertical direction. The document discharged from the ADF 5 is held on both sides of the document by the discharge tray 23 and is held in a state separated from the document on the sheet feed tray 22. Since the length of the paper discharge tray 23 in the paper discharge direction is shorter than the length of the document, the front end side of the document in the paper discharge direction is held on the paper feed tray 22 so as to hang down from the paper discharge tray 23. Accordingly, the leading end portion of the document in the paper discharge direction on the paper discharge tray 23 overlaps the rear end portion of the document in the paper feeding direction on the paper feed tray 22, but the leading end portion of the document in the paper feeding direction on the paper feed tray 22. And the rear end portion of the original on the paper discharge tray 23 in the paper discharge direction are held in two stages by the paper discharge tray 23, so that these originals are not confused. Further, by shortening the paper discharge tray 23, a necessary space on the document pressing cover 6 can be reduced, and the multifunction device 1 can be made thin and small.

  In addition, at the end of the paper feed tray 22 on the side where the ADF 5 is not provided, the posture changes between a standing posture standing up from the top surface of the paper feed tray 22 and a lying posture lying down together with the top surface of the paper feed tray 22. A document stopper 25 is provided. As shown in the figure, by placing the document stopper 25 in an upright posture, for example, when a document having the same size as the paper feed tray 22 is discharged from the ADF 5, the document is stopped by the document stopper 25, It is possible to prevent sliding from the paper feed tray 22. In this way, by receiving the discharged document with the document stopper 25, the area of the sheet feed tray 22 can be reduced, and the document pressing cover 6 integrally formed with the sheet feed tray 22 can be downsized. Further, when the document stopper 25 is not necessary, by adopting a lying posture, the multifunction device 1 can be made compact when packed or stored without protruding from the document pressing cover 6.

  As shown in FIG. 2, inside the ADF 5, a conveyance path 26 is formed in a substantially U shape in the horizontal direction so as to connect the paper feed tray 22 and the paper discharge tray 23. The conveyance path 26 includes an ADF main body 27 formed integrally with the document pressing cover 6 and an ADF cover 28 provided on the ADF main body 27 so as to be freely opened and closed. As shown in the figure, the suction chute 29 of the ADF 5 includes a horizontal plate formed in the ADF main body 27 and a partition plate 30 disposed inside the ADF cover 28 so that the paper feed tray 22 is extended. Is configured as a passage having a predetermined width in the vertical direction. The conveyance path 26 is formed in a substantially U shape from the suction chute 29 to the paper discharge chute 38 through the curved portion 37, and the curved portion 37 and the paper discharge chute 38 are also formed in the ADF main body 27, A passage having a predetermined width is continuously formed by the ADF cover 28, the partition plate 30, and the like.

  Conveying means for conveying the document is disposed in the conveying path 26. Specifically, as shown in the figure, the sheet is conveyed by a suction roller 31 and a suction nip piece 32 that is in pressure contact therewith, a separation roller 33 and a separation nip piece 34 that is in pressure contact therewith, and a conveyance roller 35 and a pinch roller 36 that is in pressure contact therewith Means are configured. The configuration of each roller and nip piece constituting the conveying means is an example, and the number and arrangement of rollers can be changed, or a pinch roller can be used in place of each nip piece, and other known conveying means can be changed. Of course.

  As shown in the figure, the suction roller 31 is provided at the approximate center of the suction chute 29 so that a part of the roller surface is exposed from the upper surface of the horizontal plane formed on the ADF main body 27. . Similarly, the separation roller 33 can be rotated at a position separated from the suction roller 31 in the paper feeding direction so that a part of the roller surface is exposed from the upper surface of the horizontal plane formed in the ADF main body 27. Is provided. A driving force from a conveyance motor 62 (see FIG. 7) is transmitted to the suction roller 31 and the separation roller 33 so as to be rotationally driven. The suction roller 31 and the separation roller 33 have the same diameter and are rotated at the same peripheral speed. In addition, a one-turn clutch is interposed in the drive transmission to the suction roller 31, and the suction roller 31 can idle for one turn.

  The suction nip piece 32 is provided at a position facing the suction roller 31 of the partition plate 30 so as to be able to swing in a direction in which the suction nip piece 32 contacts and separates from the suction roller 31. The suction nip piece 32 is elastically biased downward by a spring member (not shown), and is pressed against the roller surface of the suction roller 31 without nipping the document. Similarly, the separation nip piece 34 is provided at a position facing the separation roller 33 of the partition plate 30 so as to be able to swing in a direction in which the separation nip piece 34 contacts and separates from the separation roller 33, and is elastically downward by a spring member (not shown). As a result, the roller is pressed against the roller surface of the separation roller 33 without nipping the document. When the original is nipped by the suction nip piece 32 and the separation nip piece 34, the original is pressed against the suction roller 31 and the separation roller 33, and the rotational force of the suction roller 31 and the separation roller 33 is transmitted to the original. .

  The conveyance roller 35 is disposed in a curved portion 37 that is substantially U-shaped in the lateral direction of the conveyance path 26. The conveying roller 35 has an outer diameter such that the roller surface forms part of the curved portion 37. Similar to the suction roller 31 and the separation roller 33, the transport roller 35 is driven to rotate by receiving a driving force from the transport motor 62.

  Around the conveying roller 35, pinch rollers 36 are provided at three locations. Each pinch roller 36 is elastically biased by a spring piece, is rotatably supported by the ADF main body 27 or the ADF cover 28, and is in pressure contact with the roller surface of the transport roller 35. And if the conveyance roller 35 rotates, it will follow and the pinch roller 36 will also rotate. By these pinch rollers 36, the original is pressed against the conveying roller 35, and the rotational force of the conveying roller 35 is transmitted to the original.

  A paper discharge chute 38 is formed on the downstream side of the conveyance roller 35 in the document conveyance direction. The paper discharge chute 38 is formed between the ADF cover 28 and the partition plate 30 so as to be continuous with the curved portion 37 of the conveyance path 26 constituted by the inner surface of the ADF cover 28 and the conveyance roller 35. . Accordingly, the original supplied from the paper feed tray 22 to the conveyance path 26 is sequentially discharged through the suction chute portion 29, the curved portion 37, and the paper discharge chute portion 38 to the paper discharge tray 23.

  The ADF cover 28 is provided so as to be pivotable upward from the suction roller 31 with the paper feed tray 22 side as a pivot. By opening the ADF cover 28, the suction chute portion 29 and the curved portion 37 are opened, and the suction roller 31 and the separation roller 33 are separated from the suction nip piece 32 and the separation nip piece 34. Therefore, by opening the ADF cover 28, it is possible to eliminate a paper jam generated in the transport path 26 and to perform maintenance inside the ADF 5.

  As shown in FIGS. 2 and 3, a platen glass 20 is disposed on the upper surface of the document table 4. The platen glass 20 is used to place a document when the scanner unit 2 is used as an FBS, and is a single transparent glass plate. The casing 39 of the document placing table 4 has an opening for exposing the platen glass 20 at the center of the upper surface thereof. The platen glass 20 is sufficiently larger than the opening, and an area of the platen glass 20 exposed from the opening is a document reading area.

  An image reading unit 21 is disposed in the casing 39, that is, on the opposite side of the platen glass 20 from the document placement surface. The casing 39 is made of synthetic resin, and supports the partition plate that partitions the portion where the image reading unit 21 is disposed and the portion where the substrate of the operation panel 7 is disposed, and the platen glass 20. Support ribs, bosses for screwing various members, through holes for electrical wiring, etc. are provided, but these are appropriately designed according to the embodiment of the document table 4, Detailed description is omitted.

  As shown in FIG. 2, the image reading unit 21 includes a CIS unit 40 (image reading means), a carriage 41 (scanning means), and a scanning mechanism (not shown). The CIS unit 40 is a so-called contact-type image sensor that irradiates a document with light from a light source 42 through the platen glass 20 and condenses reflected light from the document on a light receiving element 44 by a lens 43 to convert it into an electrical signal. . The light receiving elements 44 are arranged in a line in the axial direction of the transport roller 35, that is, in the width direction of the document, for example, in units of chips, and the light source 42 and the lens 43 are also arranged in the same direction. As the light source 42, light emitting diodes (LEDs) of three colors separated into red (R), green (G), and blue (B) are used.

  As shown in FIG. 4, the CIS unit 40 is mounted on a carriage 41 and is in close contact with the platen glass 20. The carriage 41 is provided so as to be able to scan below the platen glass 20 by a belt drive mechanism which is a scanning mechanism. ing. The carriage 41 is fitted with a guide shaft 45 installed across the width direction of the casing 39 of the document table 4 and is driven by a belt drive mechanism (not shown) to slide on the guide shaft 45 and move. The carriage 41 is mounted so that the CIS unit 40 is brought into close contact with the platen glass 20 and moved on the guide shaft 45, whereby the CIS unit 40 is scanned along the platen glass 20.

  As shown in the figure, the carriage 41 carries the CIS unit 40 so as to be carried on the upper side thereof, and a shaft receiver that fits on the lower surface of the carriage 41 so as to straddle a guide shaft 45 from above. A portion 46 is formed. The shaft receiving portion 46 and the guide shaft 45 are fitted, and the carriage 41 is carried on the guide shaft 45 so as to be slidable in the axial direction of the guide shaft 45. Further, a belt gripping portion 47 projects downward from the side of the shaft receiving portion 46. The belt gripping portion 47 is for connecting the timing belt and the carriage 41 by gripping the timing belt of the belt driving mechanism. As a result, the driving force is transmitted from the belt driving mechanism to the carriage 41, and the carriage 41 moves on the guide shaft 45. In the belt driving mechanism, for example, a timing belt is wound between a driving pulley and a driven pulley, the rotation of the motor is output to the shaft of the driving pulley, and the rotation of the driving pulley causes the timing belt to move circumferentially. It is configured.

  In addition, two spring receiving portions 48 are formed on the left and right sides of the carriage 41 on which the CIS unit 40 is mounted. The spring receiving portions 48 are positioned by the spring receiving portions 48 so that they are positioned between the CIS unit 40 and the carriage 41. A coil spring 49 is interposed between the two. The coil spring 49 is in close contact with the CIS unit 40 mounted on the carriage 41 so as to be pressed against the lower surface of the platen glass 20. Rollers 50 are provided at both ends of the CIS unit 40, and the CIS unit 40 pressed against the lower surface of the platen glass 20 is brought into close contact with the lower surface of the platen glass 20 as the carriage 41 moves. While moving smoothly.

  As shown in FIG. 3, a partition member 51 is provided on the upper surface of the platen glass 20 to partition an area where the platen glass 20 is exposed as the upper surface of the document table 4. The partition member 51 is a flat plate-like member that is long in the depth direction of the document table 4, in other words, in the extending direction of the image reading unit 21. As shown in FIG. It is partitioned. As shown in FIG. 2, one end side (left side in the figure) of the platen glass 20 reaches the lower side of the conveying roller 35, and constitutes a reading surface when image reading is performed using the ADF 5.

  On the other hand, the other end side of the platen glass 20 forms a document placement surface when the scanner unit 2 is used as an FBS. The partition member 51 partitions the platen glass 20 in the left and right directions into a transported document reading region 20L that is a reading surface in the ADF 5 and a stationary document reading region 20R that is a document placing surface in the FBS. The partition member 51 is used as a document positioning reference when placing a document on the stationary document reading area 20R. Therefore, the document is placed on the stationary document reading area 20R with the center position described on the partition member 51 as a reference, and the partition member 51 shows the center position and both end positions of various document sizes such as A4 size and B5 size. The display is marked.

  As shown in FIG. 5, the partition member 51 has a guide surface 52 formed on the surface facing the document pressing cover 6. The guide surface 52 is formed by inclining the surface of the partition member 51 facing the conveyance roller 35 so that the thickness decreases toward the conveyance document reading area 20L of the platen glass 20. The leading edge of the document transported from the paper tray 22 to the transport path 26 is guided to the transported document reading area 20L. Thus, the conveyance of the original to the conveyed original reading area 20L is smoothed, and it is not necessary to provide a guide member separately from the partition member 51, and the scanner unit 2 can be reduced in size and cost by using the common member. be able to.

  Further, since the guide surface 52 guides the document before reading to the transported document reading area 20L, it is not necessary to have the lowermost portion of the guide surface 52 recessed from the surface of the platen glass 20. That is, the guide surface 39A formed on the downstream side of the transported document reading area 20L guides the scanned document so as to be scooped up from the transported document reading area 20L. If it protrudes from the surface, the leading edge of the document after reading may come into contact with the lowermost end of the guide surface 39A and cause a jam or the like. Therefore, the lowermost end of the guide surface 39A is preferably recessed from the surface of the platen glass 20.

  On the other hand, even if the lowermost end of the guide surface 52 of the partition member 51 protrudes from the platen glass 20, there is no possibility that the document abuts on the partition member 51 and a jam occurs. Therefore, it is not necessary to divide the platen glass 20 into the conveyed document reading region 20L and the stationary document reading region 20R, and the bottom end of the guide surface 52 of the partition member 51 does not need to be recessed from the platen glass 20, and these regions are formed as one sheet. The platen glass 20 is configured, and the partition member 51 can be disposed on the upper surface of the platen glass 20. Thereby, the configuration of the platen glass 20 and the partition member 51 is simplified, and the assembly of the scanner unit 2 is facilitated.

  As shown in FIG. 5, a reference member 53 is provided on the lower surface side of the partition member 51 so as to be interposed between the platen glass 20. The reference member 53 is a lightness reference for the CIS unit 40. Specifically, the reference member 53 is a thin-film strip-like member that covers almost the entire lower surface of the partition member 51, and, as shown in FIG. 6, has three regions in the sub-scanning direction of the CIS unit 40, that is, in the horizontal direction of the drawing. Have The left end side region 53 </ b> A is a region colored in white and is used for light amount adjustment of the CIS unit 40 and acquisition of white level data. The central area 53B is an area colored in black and is used for acquiring black level data of the CIS unit 40. The boundary between the left end region 53A and the central region 53B is a reference in the sub-scanning direction of the CIS unit 40. The right end region 53C is a region in which the center in the depth direction is colored white and both ends are colored black, and serves as a reference in the main scanning direction of the CIS unit 40. Such a reference member 53 is interposed between the partition member 51 and the platen glass 20 so that each region is in the same direction as the extending direction of the CIS unit 40.

  Thus, by providing the reference member 53 on the lower surface of the partition member 51, for example, it is not necessary to secure a space for providing the reference member 53 at the scanning end on the left side of the document placement table 4, and the document placement table 4. Can be miniaturized. In particular, by reducing the space on the side of the document table 4 where the transported document reading area 20L is provided, that is, the left side of the document table 4 in FIG. 3, the transport roller 35 of the ADF 5 is made as much as possible. The document pressing cover 6 can be disposed at the end in the width direction, and the dimension of the scanner unit 2 in the width direction can be reduced. In addition, since the partition member 51 and the reference member 53 have substantially the same width, the width of the partition member 51 is reduced, so that the area of the platen glass 20 exposed on the upper surface of the document table 4 can be reduced. . Thereby, the area of the upper surface of the document table 4 can be reduced, and the scanner unit 2 can be downsized.

  FIG. 7 shows the configuration of the control unit 55 of the multifunction machine 1. The control unit 55 controls the overall operation of the multifunction machine 1 including not only the scanner unit 2 but also the printer unit 3. However, since the components of the printer unit 3 do not need to be described in detail in the present embodiment, the components of the printer unit 3 are omitted in the drawing. As shown in the figure, the control unit 55 is configured as a microcomputer mainly including a CPU 56, a ROM 57, a RAM 58, and an EEPROM (Electrically Erasable and Programmable ROM) 59, and an ASIC (Application Specific Integrated Circuit) via a bus 60. 61 is connected.

  The ROM 57 stores a program for controlling various operations of the multifunction machine 1. The RAM 58 is used as a storage area or work area for temporarily recording various data used when the CPU 56 executes the program. For example, the light amount adjustment value of the light source 42 of the CIS unit 40 and the white level data and black level data acquired for the reference member 53 are stored in the RAM 58. The EEPROM 59 is a storage area for storing various settings and flags that should be kept even after the power is turned off. For example, the light quantity setting value of the CIS unit 40 is stored. The light amount setting value is a light amount adjustment value that will be obtained when the CIS unit 40 performs a light amount adjustment to be described later on the reference member 53 with the document pressing cover 6 closed. It is input and set in advance at the time of shipment or factory shipment.

  The ASIC 61 generates a phase excitation signal and the like for energizing the conveyance (LF) motor 62 in accordance with a command from the CPU 56, applies the signal to the drive circuit 63 of the conveyance motor 62, and drives the drive signal via the drive circuit 63. , The rotation control of the transport motor 62 is performed.

  The drive circuit 63 drives the conveyance motor 62 connected to the suction roller 31, the separation roller 33, and the conveyance roller 35, and receives an output signal from the ASIC 61, and an electric signal for rotating the conveyance motor 62. Form. In response to the electrical signal, the transport motor 62 rotates, and the rotational force of the transport motor 62 is transmitted to the separation roller 33 and the transport roller 35 via a known drive mechanism including a gear, a drive shaft, and the like.

  Similarly, the ASIC 61 generates a phase excitation signal and the like for energizing the carriage (CR) motor 64 in accordance with a command from the CPU 56, applies the signal to the drive circuit 65 of the carriage motor 64, and passes through the drive circuit 65. Thus, the carriage motor 64 is rotated by energizing the carriage motor 64 with a drive signal.

  The drive circuit 65 drives the carriage motor 64 of the belt drive mechanism connected to the carriage 41. The drive circuit 65 receives an output signal from the ASIC 61 and forms an electrical signal for rotating the carriage motor 64. The carriage motor 64 is rotated in response to the electric signal, and the carriage 41 is scanned by transmitting the rotational force of the carriage motor to the carriage 41 via a known belt driving mechanism.

  Further, the ASIC 61 includes a lead sensor 66 for detecting a document in the conveyance path 26, a rotary encoder 67 provided for detecting the rotation amounts of the separation roller 33 and the conveyance roller 35, and a movement amount of the carriage 41. Is connected to the linear encoder 68.

  The ASIC 61 is connected to a CIS unit 40 that reads an image of a document conveyed on the conveyance path 26. Based on the control program stored in the ROM 57, light amount adjustment, acquisition of white level data and black level data, and image reading are performed. In the present embodiment, the CIS unit 40 also functions as an opening / closing detection unit that detects opening / closing of the document pressing cover 6. More specifically, when the document pressing cover 6 is opened, the platen glass 20 on the upper surface of the document placing table 4 is exposed, and external light enters the inside of the document placing table 4 through the platen glass 20. On the other hand, when the document pressing cover 6 is closed, the platen glass 20 is covered with the document pressing cover 6, so that external light is blocked and does not enter the document placing table 4.

  Since the CIS unit 40 is disposed inside the document placing table 4, as will be described later, when the CIS unit 40 performs light amount adjustment on the reference member 53, the obtained light amount adjustment value is within a predetermined range. The opening / closing of the document pressing cover 6 can be determined on the basis of whether or not it is within. That is, if external light has entered, a constant output can be obtained even if the light amount of the light source 42 of the CIS unit 40 is small by the external light amount, so the light amount adjustment value becomes small. Therefore, if the light amount adjustment value is smaller than the predetermined range, it can be determined that the document pressing cover 6 is open. Such an open / close detection means includes the CPU 56, ROM 57, RAM 58, EEPROM 59, and CIS unit 40. The predetermined range is set based on a value obtained by multiplying the light amount setting value stored in the EEPROM 59 by a predetermined coefficient.

  Thus, by determining whether the document pressing cover 6 is opened or closed based on the detection of external light by the CIS unit 40, there is no need to separately provide a sensor for detecting the opening / closing of the document pressing cover 6. Miniaturization and cost reduction are realized. Note that the CIS unit 40 may be operated at all times while the power of the multifunction device 1 is turned on to detect the presence or absence of external light. In this case, when the CIS unit 40 detects outside light, that is, when the output of the CIS unit 40 is outside the predetermined range, the document pressing cover 6 is in the open posture, and when the output is within the predetermined range, the document pressing cover. 6 can be determined to be a closed posture. The predetermined range is set based on, for example, a black level reference signal output from the CIS unit 40.

  Further, the ASIC 61 transmits and receives data to and from an operation panel 7 for instructing operation of the multifunction device 1, a slot portion 8 into which various small memory cards are inserted, an external device such as a personal computer via a parallel cable or a USB cable. A parallel interface 69 and a USB interface 70 for performing, an NCU (Network Control Unit) 71 and a MODEM 72 for realizing a facsimile function are also connected.

Hereinafter, the operation of the scanner unit 2 will be described.
When the scanner unit 2 is used as an FBS, the document pressing cover 6 is opened and the document G is placed on the stationary document reading area 20R of the platen glass 20. Then, the document pressing cover 6 is closed and the document G is fixed on the platen glass 20. Thereafter, when the start button on the operation panel 7 is pressed, the control unit 55 moves the carriage 41 along the platen glass 20, and the CIS unit 40 places the carriage 41 on the stationary document reading area 20R of the platen glass 20 during the movement. The image of the placed original G is read.

  On the other hand, when the ADF 5 is used, the document pressing cover 6 is closed with respect to the document placing table 4. Then, the original G to be read is placed on the paper feed tray 22. The document G may be one sheet or a plurality of sheets. For example, when reading images of a plurality of originals G of the same size, the originals G are overlapped and aligned, and one end thereof is inserted into the suction chute 29 from the paper feed tray 22.

  When the start button on the operation panel 7 is pressed, the control unit 55 drives the motor to rotationally drive the suction roller 31, the separation roller 33, and the conveyance roller 35 at a predetermined timing. Then, the sheets are separated one by one from the lowermost document G that directly receives the rotational force of the suction roller 31 and the separation roller 33 and sent to the conveyance path 26. The fed document G is guided to the transport path 26 and transported to the transported document reading area 20L, and the image of the document G is read by the CIS unit 40 stationary under the transported document reading area 20L. Then, the original G that has been read is discharged from the discharge chute 38 to the discharge tray 23.

  In such image reading by the scanner unit 2, before the CIS unit 40 starts reading an image of the original G, as the output adjustment of the CIS unit 40, the light amount adjustment of the light source 42 and the acquisition of the white level data and the black level data are performed. Is done.

  As will be described in detail with reference to FIGS. 5 to 10, first, the control unit 55 moves the carriage 41 to the reference position RP. The reference position RP is a boundary between the left end region 53A and the center region 53B of the reference member 53, and can be determined by changing the output of the CIS unit 40 between white and black. Prior to image reading, the carriage 41 is moved below the reference member 53, that is, to the home position HP in FIG. The home position HP is a position corresponding to the left end region 53 </ b> A of the reference member 53. In this way, by setting the same position as the reference member 53 as the home position HP as the standby position of the CIS unit 40, the distance by which the carriage 41 is moved before the light amount adjustment with respect to the reference member 53 is shortened. The image reading operation can be speeded up.

  And the control part 55 performs the light quantity adjustment of the light source 42 of the CIS unit 40 with respect to the reference member 53 (S1). Specifically, first, light is irradiated from the light source 42 to the region 53A of the reference member 53 with a sufficiently small amount of light. In this case, since the reflected light from the region 53A is also small, the output from the light receiving element 44 of the CIS unit 40 is also small. Then, the light amount of the light source 42 is increased stepwise until the output of the light receiving element 44 reaches a desired value, and when the output of the CIS unit 40 reaches the desired value S as shown in FIG. The light amount is stored in the RAM 58 as a light amount adjustment value (S2).

  Subsequently, the control unit 55 acquires white level data and black level data of the CIS unit 40 from the reference member 53 (S3, S4). In detail, the control unit 55 irradiates the region 53A with light amount adjustment values from the light source 42 of the CIS unit 40 at a position corresponding to the left end region 53A of the reference member 53 with the carriage 41. Then, the reflected light from the region 53A is converted into an electric signal by the light receiving element 44 to acquire white level data (S3). The white level data may be acquired a plurality of times for the area 53A and the average may be used, or may be performed while moving the carriage 41 within the area 53A.

  After acquiring the white level data, the control unit 55 drives the carriage motor 64 to move the carriage 41 to a position corresponding to the central region 53B of the reference member 53. Then, black level data is acquired from the electrical signal of the light receiving element 44 obtained with the light source 42 turned off (S4). The black level data may be acquired a plurality of times as described above or may be performed while moving the carriage 41 within the area 53B. Further, the acquisition of the white level data and the acquisition of the black level data may be reversed. The white level data and black level data thus obtained are stored in the RAM 58 for use as reference data for shading correction in image reading (S5).

  Subsequently, it is determined whether or not the obtained light amount adjustment value is within a predetermined range (S6). This predetermined range is determined based on the light amount setting value stored in the EEPROM 59. Specifically, the light quantity setting value input to the EEPROM 59 at the time of shipment of the multifunction device 1 is determined by multiplying it by a predetermined coefficient such as 0.8. The light amount setting value is a light amount adjustment value that will be obtained when the document pressing cover 6 is closed and the light amount adjustment is performed, and is input and set in the EEPROM 59 in advance.

  As shown in FIG. 5, when the document pressing cover 6 is in the closed position, the transported document reading area 20 </ b> L is covered with the transporting roller 35 and the entire platen glass 20 is covered with the document pressing cover 6. Therefore, the outside light L does not enter the vicinity of the reference member 53. Accordingly, as shown in FIG. 9A, when the light intensity adjustment is performed on the reference member 53 so that the output of the CIS unit 40 becomes a predetermined output S, a value almost the same as the light intensity setting value is obtained as the light intensity adjustment value. can get. Therefore, even if there is some variation due to the stability of the light source 42 and the light receiving element 44, the light amount adjustment value within a certain range can be obtained from the light amount setting value. Therefore, if the obtained light amount adjustment value is within a predetermined range with respect to the light amount setting value, the control unit 55 determines that the document pressing cover 6 is in the closed posture.

  On the other hand, when the scanner unit 2 is used as an FBS, if a thick document such as a book document is placed on the platen glass 20, the document pressing cover 6 cannot be completely closed. Further, when a part of a document having a size larger than the stationary document reading area 20R of the platen glass 20 is read, it is assumed that the image reading is performed without closing the document pressing cover 6 in order to confirm the reading position. Is done. As shown in FIG. 10, when the document pressing cover 6 is in the open position, the transported document reading area 20L is exposed, so that external light L enters the document table 4 from the transported document reading area 20L.

  The outside light L is reflected on a member inside the document table 4, is incident on the reference member 53 while being reflected within the thickness of the platen glass 20, or is incident on the CIS unit 40 at the home position HP. In particular, as shown in FIG. 2, the CIS unit 40 is arranged with the light receiving element 44 facing upward, so that external light L that has entered from the upper surface of the CIS unit 40 into the output of the light receiving element 44. Easy to influence. Therefore, if the light amount adjustment is performed on the reference member 53 in a state where the external light L has entered, the light amount emitted from the light source 42 is small by the amount of the external light L as shown in FIG. Even with the light quantity, the light receiving element 44 receives the sum of the reflected light quantity and the external light L, so that a predetermined output S is obtained. As a result, the light source 42 has a light amount adjustment value that results in an output S1 that is smaller by the amount of external light L indicated by hatching in the drawing. Therefore, if the coefficient is 0.8, if the light amount adjustment value that is the output S1 is less than 80% of the light amount setting value, the control unit 55 determines that the document pressing cover 6 is in the open posture.

  Subsequently, the control unit 55 moves the carriage 41 to a position P1 that is a reading start position in the stationary document reading area 20R. When the control unit 55 determines that the document pressing cover 6 is in the closed position, the control unit 55 moves the carriage 41 along the platen glass 20 while irradiating light from the light source 42 with the light amount adjustment value obtained for the reference member 53. Then, the reflected light from the original G is converted into an electrical signal by the light receiving element 44, and the image is read (S7). When the document pressing cover 6 is closed, the light amount adjustment (S1) of the light source 42 described above is not affected by the external light L, so that an appropriate light amount adjustment value is obtained. Therefore, by irradiating the original G with light from the light source 42 with the light amount adjustment value, an output equivalent to the output of the CIS unit 40 obtained for the white of the region 53A and the black of the region 53B of the reference member 53 is obtained. , Obtained from the white portion and black portion of the original G.

  On the other hand, when determining that the document pressing cover 6 is in the open position, the control unit 55 moves the carriage 41 along the platen glass 20 while irradiating light from the light source 42 with the light amount setting value stored in the EEPROM 59. The reflected light from the original G is converted into an electrical signal by the light receiving element 44 and image reading is performed (S8). When the document pressing cover 6 is opened, the light amount adjustment (S1) of the light source 42 described above is affected by the external light L. On the other hand, as shown in FIG. 10, the reading start position P1 of the stationary document reading area 20R is sufficiently separated from the transported document reading area 20L, and thus hardly affected by the external light L. Accordingly, when the light source 42 irradiates light to the original G with the light amount adjustment value obtained with respect to the reference member 53, that is, the light amount adjustment value that becomes the output S1 shown in FIG. The amount of light received by the light receiving element 44 is insufficient.

  If the light source 42 irradiates light to the original G with the light amount adjustment value that becomes the output S1, the output is smaller than the output of the CIS unit 40 obtained for the white of the region 53A and the black of the region 53B of the reference member 53. However, since it is obtained from the white portion and the black portion of the original G, the read image becomes dark overall. Therefore, even if the document pressing cover 6 is opened by irradiating light from the light source 42 using the light amount setting value stored in the EEPROM 59 without using the light amount adjustment value affected by the external light, the document Light can be emitted from the light source 42 with the amount of light obtained when the pressing cover 6 is closed.

  Subsequently, the control unit 55 performs shading correction on data sequentially output from the CIS unit 40 during the movement of the carriage 41 (S9). Specifically, the output signal of the CIS unit 40 is converted from analog to digital, and shading correction is performed based on the reference data stored in the RAM 58. The reference data includes white level data obtained by irradiating light from the light source 42 to the region 53A of the reference member 53 with the light amount adjustment value obtained in each state regardless of whether the document pressing cover 6 is opened or closed, and the light source. This is the black level data obtained for the area 53B with 42 turned off.

  When the document pressing cover 6 is closed, the light amount adjustment value obtained by adjusting the light amount with respect to the reference member 53 is not affected by the external light L. Since the acquisition of the white level data and black level data for the reference member 53 and the image reading of the original G are also performed without being affected by the external light L, the light amount adjustment values obtained in all of these operations are used. That's fine.

  On the other hand, when the document pressing cover 6 is opened, the light amount adjustment value obtained by adjusting the light amount with respect to the reference member 53 is affected by the external light L. However, since the white level data and the black level data are acquired for the same reference member 53 affected by the external light L, if the white level data and the black level data are acquired using the light amount setting value, As shown in FIG. 9C, the output corresponding to the external light L indicated by hatching in the figure is added to the desired output S that should be originally obtained for the region 53A of the reference member 53, and is larger than the output S. The white level data of the output S2 is acquired.

  On the other hand, since the image reading of the original G is hardly affected by the external light L as described above, an output equivalent to the output S can be obtained from the white portion of the original G. On the other hand, if the shading correction is performed on the basis of the white level data from which the output S2 is obtained, the read image becomes dark overall. Therefore, the white light level data is acquired for the reference member 53 by irradiating light from the light source 42 using the light amount adjustment value obtained by adjusting the light amount for the reference member 53 affected by the external light L. Thus, reference data with an appropriate amount of light considering the external light L can be acquired.

  The output data of the CIS unit 40 that has been subjected to the shading correction is stored in the RAM 58 as image data. When the image reading is completed, the control unit 55 returns the scanning carriage 41 to the home position HP and enters a standby state.

  As described above, according to the scanner unit 2 of the multifunction machine 1, when the document pressing cover 6 is closed with respect to the document placing table 4, the control unit 55 adjusts the light amount with respect to the reference member 53. If the original G is read by irradiating light from the light source 42 of the CIS unit 40 based on the obtained light quantity adjustment value, and the original pressing cover 6 is opened with respect to the original placing table 4 The control unit 55 reads the image of the document G by irradiating light from the light source 42 of the CIS unit 40 using the predetermined light amount setting value as the light amount value. The image reading of the original G by the CIS unit 40 can be performed without using the light amount adjustment value affected by the light L. Thereby, it is possible to prevent deterioration of the read image such as the read image becoming dark or blurred.

  In the present embodiment, the light amount setting value is input and set in the EEPROM 59 at the time of manufacture or factory shipment, but the light amount setting value according to the present invention is not limited to such a preset value. . Specifically, for example, in the operation of the scanner unit 2 shown in FIG. 8, when the control unit 55 determines that the obtained light amount adjustment value is within a predetermined range (S6), that is, the document pressing cover. 6 is closed with respect to the document table 4, the light amount adjustment value stored in the RAM 58 by the light amount adjustment (S1) performed on the reference member 53 (S2) is stored in the EEPROM 59, and thereafter It can be used as a light amount setting value in image reading.

  In addition to the image reading operation by the scanner unit 2, for example, the control unit 55 operates the CIS unit 40 and the carriage 41 to adjust the light amount with respect to the reference member 53 at a predetermined time interval when the power is turned on or after the power is turned on. I do. When it is determined that the obtained light amount adjustment value is within a predetermined range, the light amount adjustment value can be stored in the EEPROM 59 as a light amount setting value and used as a light amount setting value in subsequent image reading.

  In the present embodiment, the light amount of the light source 42 of the CIS unit 40 is adjusted with respect to the reference member 53, and it is determined whether or not the obtained light amount adjustment value is within a predetermined range. In other words, the CIS unit 40 is similarly used as an open / close detection means according to the present invention, based on the read value of the CIS unit 40 obtained by another operation. It is also possible to determine whether the pressing cover 6 is opened or closed.

  Specifically, the light source 42 of the CIS unit 40 is turned off and the reference member 53 is read. If the external light L has not entered the document table 4, the read value obtained by turning off the light source 42 is a value close to the black level data, but if the external light L has entered, Since the light receiving element 44 reads the external light L, a reading value higher than the black level data is obtained. Therefore, for example, when an appropriate range is set for the read value based on the black level reference signal output from the CIS unit 40 and the obtained read value is outside the predetermined range, the document pressing cover 6 is It can be determined as an open posture.

  Further, as another operation, the light source 42 of the CIS unit 40 is turned off, the left end region 53A and the central region 53B of the reference member 53 are read, and the opening / closing of the document pressing cover 6 is determined from the difference between these read values. can do. If the outside light L does not enter the document table 4, the read value obtained by turning off the light source 42 is the read value of both the white region 53A and the black region 53B. Both values are equivalent to the black level data, but if the outside light L enters, a difference occurs between both reading values due to the difference in reflectance. Therefore, an appropriate threshold value is set for the difference between the reading values, and when the obtained reading value difference is equal to or larger than the threshold value, it is possible to determine that the document pressing cover 6 is in the open posture.

  Further, instead of using the CIS unit 40 as an open / close detection unit according to the present invention, the opening / closing of the document pressing cover 6 may be directly detected using a magnet sensor or an optical sensor.

  In the present embodiment, the case where the CIS unit 40 which is a contact image sensor is used as the image reading device according to the present invention has been described. However, the image reading device according to the present invention is not limited to the contact image sensor. For example, a reduction optical system CCD image sensor can be used.

FIG. 1 is a perspective view showing an external configuration of a multifunction machine 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA showing the main configuration of the ADF 5. FIG. 3 is a plan view showing the configuration of the document table 4. FIG. 4 is a longitudinal sectional view of the document placing table 4 showing the configuration of the carriage 41. FIG. 5 is an enlarged cross-sectional view showing a configuration in the vicinity of the reference member 53. FIG. 6 is a plan view showing the configuration of the reference member 53. FIG. 7 is a block diagram illustrating a configuration of the control unit 55 of the multifunction machine 1. FIG. 8 is a flowchart showing output adjustment of the CIS unit 40. FIG. 9A is a graph showing the output of the CIS unit 40 in the light amount adjustment, and FIG. 9B is a graph showing the output of the CIS unit 40 in the light amount adjustment with the document pressing cover 6 open. FIG. 9C is a graph showing the output of the CIS unit 40 when the light source 42 is irradiated with the light amount setting value with the document pressing cover 6 opened. FIG. 10 is an enlarged cross-sectional view showing a configuration in the vicinity of the reference member 53 in a state where the document pressing cover 6 is opened. FIG. 11 is a perspective view showing a schematic configuration of a conventional image reading apparatus 90.

Explanation of symbols

1 ... Multifunction machine (image reading device)
4 ... Document placement table 5 ... ADF (automatic document feeder)
6 ... Document holding member 20 ... Platen glass (transmission member)
20L ... Conveyed document reading area 20R ... Still document reading area 22 ... Feeding tray 23 ... Discharge tray 40 ... CIS unit (image reading means, contact type image sensor, open / close detection means)
41... Carriage (scanning means)
42 ... light source 51 ... partition member 52 ... guide surface 53 ... reference member 55 ... control unit (control means)
G ... manuscript

Claims (12)

A document placing table having a transmissive member for placing the document;
A document pressing member provided on the document placing table so as to be openable and closable so as to cover the transmission member;
Image reading means for irradiating a document from a light source and reading an image recorded on the document based on the reflected light;
A scanning unit disposed on a side opposite to the document placement surface of the transmission member, mounted with the image reading unit, and reciprocating in a predetermined direction along the transmission member;
Open / close detecting means for detecting opening / closing of the document pressing member;
Control means for controlling the image reading of the image reading means and the reciprocating movement of the scanning means;
An image reading apparatus comprising: a reference member that is disposed in an area exposed as an outer surface of the document placing table and serves as a lightness reference for the image reading unit;
The control unit is configured to use a predetermined light amount setting value as a light amount value of light emitted from a light source at the time of image reading when the open / close detection unit detects an open posture of the document pressing member. .   The image reading apparatus according to claim 1, wherein the control unit uses a predetermined light amount value set in advance as the light amount setting value.   The control means stores a light quantity adjustment value obtained by adjusting the light quantity of the light source of the image reading means with respect to the reference member when the open / close detection means detects the closed posture of the document pressing member. The image reading apparatus according to claim 1, wherein the light amount adjustment value is used as the light amount setting value.   4. The image reading apparatus according to claim 1, wherein the open / close detection unit detects opening / closing of the document pressing member by detecting presence / absence of external light entering the document placement table. 5.   The open / close detecting means detects that the document pressing member is in an open position when a light quantity adjustment value obtained by the light reading adjustment performed on the reference member by the image reading means is outside a predetermined range. Item 5. The image reading apparatus according to Item 4.   5. The open / close detection means detects that the document pressing member is in an open position when a read value when the image reading means turns off a light source and reads the reference member is out of a predetermined range. The image reading apparatus described in 1. The reference member is provided with a white portion and a black portion in the moving direction of the scanning means,
The open / close detection unit is configured to detect a document holding member when a difference between reading values when the image reading unit turns off a light source and reads a white portion and a black portion of the reference member is a predetermined threshold value or more. The image reading apparatus according to claim 4, wherein the image reading apparatus detects an open posture.   The control means irradiates the reference member with light from the light source based on the light quantity adjustment value obtained by adjusting the light quantity of the light source of the image reading means to the reference member, and The image reading apparatus according to claim 1, which acquires a brightness standard.   The reference member is interposed between the transmissive member and a partition member that is disposed in a region where the transmissive member is exposed as an outer surface of the document table and divides the region. The image reading apparatus according to any one of 1 to 8.   The partition member includes an area where the transmission member is exposed as an outer surface of the document placing table, a transport document reading area for the image reading unit to read an image of a document transported in a predetermined direction, and the image reading The image reading apparatus according to claim 9, wherein the means divides into a stationary document reading region for reading an image of the document placed on the transmissive member. The pressing member is provided with an automatic document transport mechanism that transports a document loaded in a paper feed tray to the transported document reading area and discharges it to a paper discharge tray.
The image reading apparatus according to claim 10, wherein the partition member is formed with a guide surface for guiding a document before reading to a transported document reading region on a surface on the pressing member side. The image reading apparatus according to claim 1, wherein the image reading unit is a contact image sensor.

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