JP5703162B2 - Image reading apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an image reading apparatus that reads a document. The present invention also relates to an image forming apparatus such as a multifunction machine, a copying machine, a printer, and a FAX apparatus provided with the image reading apparatus.

  The image reading device guides the light emitted from the light source and reflected by the document to the image sensor to obtain image data. In addition, the image reading apparatus may be provided in an image forming apparatus such as a multifunction machine, a copier, or a FAX apparatus. In some cases, the image reading apparatus is provided with a plurality of light sources. However, it is assumed that all the light sources are turned on, and if one of the light sources fails, accurate reading cannot be performed. An example of an image reading apparatus that detects a failure of a plurality of LEDs arranged in a row is described in Patent Document 1.

  Specifically, Patent Document 1 discloses a glass member on which an image reading object is placed, a light source unit in which a plurality of light emitting elements are arranged in one or a plurality of rows, and irradiates light on the image reading object, and an image reading object. An image pickup means for picking up an image reading object based on a result of receiving the reflected light reflected by the object, and at least a light source unit, and the glass member is placed on the side opposite to the image reading object across the glass member A traveling body that is movable along the traveling body, and a white reference member that is disposed at an end portion of the glass member in the traveling body movement direction and serves as a white reference for performing shading correction of reflected light received by the imaging means. Is detected to detect the failure of the light emitting element based on the result of receiving the reflected light reflected by the white reference member by the imaging means. mode Image reading apparatus is described with. With this configuration, it is attempted to detect a failure of a light emitting element corresponding to a non-uniform portion among a plurality of light emitting elements arranged in a row based on the presence or absence of a non-uniform portion in reflected light received using the white reference member. To do. (See Patent Document 1: Claim 1, paragraph [0009], etc.).

JP 2009-010830A

A CIS (Contact Image Sensor) type image sensor (contact image sensor) may be used for the image reading apparatus. In some cases, lamps are arranged on both sides of a CIS image sensor (line sensor). When lamps are arranged on both sides of the line sensor, even if one of the lamps does not turn on due to a failure or the like, the amount of light in the main scanning direction is uniform and the image quality is reduced, but a certain degree of reading can be performed.

  When lamps are arranged on both sides of such an image sensor, it is preferable that the amount of light emitted by each lamp (light emission level) is uniform. When reading a document with wrinkles or creases, if there is a difference in the amount of light from the two lamps that irradiate the wrinkles or creases, the wrinkled part of the document (the shadow part due to the wrinkles) ) Is emphasized, resulting in a reading result (image data). In other words, when the light quantity of the lamps on both sides is not uniform, when a document with irregularities such as wrinkles and folds is read, there is a problem that shadows are formed on the irregularities, and originally unnecessary irregularities appear clearly in the reading result. This problem becomes more conspicuous as the difference in the amount of light between the two lamps increases, such as when one of the lamps does not light due to a failure or the like.

  In Patent Document 1, although a plurality of light emitting elements are arranged in a row, the number of lamps extending in the main scanning direction is one, and lamps are not arranged on both sides of the image sensor (Patent Document 1). The described image reading apparatus is a so-called CCD system. In other words, a plurality of light emitting elements are not arranged in rows on both sides of the image sensor. Moreover, there is no description which suggests said problem. Therefore, the invention described in Patent Document 1 cannot solve the above problem.

  The present invention has been made in view of the above-described problems of the prior art, and can reduce the emphasis of the wrinkled portion of the document by making it possible to adjust the light quantity of the lamps arranged on both sides of the image sensor. Therefore, it is an object to improve image quality in reading.

Claim image reading apparatus according to 1, primary and image sensor are arranged a plurality of light receiving elements in the scanning direction, each provided in the main scanning direction and the longitudinal direction against the image sensor on the left and right sides of the sub-scanning direction, Each of which includes two lamps each having a light source, a reading unit that turns on each of the light sources when reading a document and performs reading by the image sensor, and a moving mechanism that moves the reading unit in the sub-scanning direction; A light emission control unit that controls light emission of the light source of each lamp, and a moving path of the reading unit, and is provided above the reading unit, and on the lower surface, at the center in the sub-scanning direction, as well as it has a downward convex portion, and a white reference plate flat surface portion is provided on the upper side than the lower surface of the convex portion on the left and right sides of the sub-scanning direction with respect to the convex portion, the image Based on the output value of the light receiving elements of Nsa, anda density checking unit for determining the density value is a value indicating the concentration of the flat surface portion in the sub-scanning direction left, the said flat surface section in the sub-scanning direction left The irradiation light from the lamp on the left side reaches the flat surface part on the left side in the sub-scanning direction at a predetermined distance from the step with respect to the convex portion and left on the left side in the sub-scanning direction. The left adjustment position is a position where the light is blocked by a step and does not reach the flat surface portion on the left side in the sub-scanning direction, and the flat surface portion on the right side in the sub-scanning direction and the convex portion among the flat surface portions on the right side in the sub-scanning direction The irradiation light from the right lamp reaches the flat surface portion on the right side in the sub-scanning direction at a predetermined distance from the step, and the irradiation light from the left lamp reaches the step. In front of the right side of the sub-scanning direction The moving mechanism to a position which does not reach the flat surface portion, and right adjustment position, together with the image sensor moves the reading unit in a position for reading the left adjustment position, the a position where the image sensor reads the right adjustment position The reading unit is moved, the reading unit reads at the left adjustment position and the right adjustment position, and the density confirmation unit reads the density value obtained by reading at the left adjustment position and the right adjustment position. read individually determined adjustment amount of the light amount of the light source of each of the obtained said lamp such that the difference is eliminated in the density values at the light emission control unit of the light source of each of the lamps on the basis of the adjustment amount The amount of light was adjusted individually .

  If a step is provided on the white reference plate, it is possible to read the light from one of the lamps by reflecting the light from the convex portion and not reaching the image sensor. Therefore, according to this configuration, the density confirmation unit adjusts the light amount of the light source so that there is no difference between the density value obtained by reading at the left adjustment position and the density value obtained by reading at the right adjustment position. Determine. This makes it possible to recognize the difference between the light amounts of the two lamps (density value difference) by using the image sensor originally provided in the image reading apparatus without installing a separate sensor. Then, the light emission control unit adjusts the light amount of the light source so that there is no difference in density value. Accordingly, since the light amounts of the lamps on both sides of the image sensor are adjusted so that the light amounts are equal, it is possible to reduce the emphasis on the wrinkles and folds of the document and improve the image quality in reading.

  According to a second aspect of the present invention, in the first aspect of the invention, when the density confirmation unit recognizes that the reading at the left adjustment position is darker, the light quantity of the light source of the left lamp is increased. The adjustment amount is determined as follows, and when the density confirmation unit recognizes that reading at the right adjustment position is darker, the adjustment amount is determined so as to increase the light amount of the light source of the right lamp. .

  According to this configuration, when the density confirmation unit recognizes that the reading at the left adjustment position is darker, the adjustment amount is determined to increase the light amount of the light source of the left lamp, and the density confirmation unit is at the right adjustment position. When it is recognized that the reading is darker, the adjustment amount is determined so as to increase the light amount of the light source of the right lamp. Thereby, the light quantity of the lamps on both sides of the image sensor can be adjusted so that the light quantity becomes equal while securing the total light quantity of the lamps on both sides.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the density check section outputs an output value of one light receiving element or outputs of the plurality of light receiving elements when read at the left adjustment position. Based on the average value of the value, the density value of the left adjustment position is determined, based on the average value of the output value of one of the light receiving elements or the output value of the plurality of light receiving elements when read at the right adjustment position, The density value at the right adjustment position was decided.

  According to this configuration, the density confirmation unit determines the density value of the left adjustment position based on the output value of one light receiving element or the average value of the output values of a plurality of light receiving elements when read at the left adjustment position, The density value at the right adjustment position is determined based on the output value of one light receiving element or the average value of the output values of a plurality of light receiving elements when read at the adjustment position. Thereby, if the density value is determined based on the output value of one light receiving element, the density value at each adjustment position and the difference between the density values (difference in the amount of light) can be obtained with extremely simple processing. Alternatively, by determining the density value by taking the average of the output values of a plurality of light receiving elements, the difference in density value (the amount of light) can be reduced while reducing individual differences and variations in the reading characteristics of each light receiving element (light receiving element). Difference).

  According to a fourth aspect of the present invention, in the first to third aspects of the invention, the moving mechanism is arranged such that when the light amount of any one of the light sources is adjusted to be in a position to read the convex portion. The reading unit is moved, the light emission control unit causes each light source to emit light with the adjusted light amount, the reading unit reads the convex portion of the white reference plate, and the density confirmation unit includes the convex portion. When a reference value is determined based on an output value of one of the light receiving elements when reading a portion or an average value of output values of the plurality of light receiving elements, and the reference value is not within a predetermined allowable range The light amount of some or all of the light sources is reduced or increased so as to be within the allowable range.

  If the total amount of light from the lamp is too large, a portion of the original that is brighter than a certain level may be read almost white (out-of-white). Also, if the total amount of light from the lamp is too small, a dark portion of a document that is darker than a certain level may be read as almost black (black crushing). Therefore, according to this configuration, the density confirmation unit determines the reference value based on the output value of one light receiving element when the convex portion is read or the average value of the output values of the plurality of light receiving elements, and the reference value is When it is not within the predetermined allowable range, the light amount of some or all of the light sources is reduced or increased so that it is within the allowable range. Thereby, as a result of the light amount adjustment, it is possible to prevent the total light amount of each lamp from becoming too much or too little. Here, the “allowable range” can be arbitrarily determined, and an appropriate and suitable reference value range determined in advance by experiments or the like so as to avoid the occurrence of overexposure or blackout in reading the document. It is.

The invention according to claim 5 is the invention of claim 1, wherein the moving mechanism, the image sensor in the left adjustment position from the left side of the step and the length of the reading line comma for reading The reading unit is moved to the left adjustment position and the right adjustment position with the same distance from the step on the right side to the reading line at which the image sensor reads at the right adjustment position. It was decided to.

According to this arrangement, the moving mechanism includes a distance in the reading line comma the image sensor in the left adjustment position from the left side of the step is to read, the image sensor at right adjustment position from the right side of the step reading to read The reading unit is moved to the left adjustment position and the right adjustment position with the same distance as the line. Thereby, the positional relationship between the reading line and the step at the left adjustment position and the positional relationship between the reading line and the step at the right adjustment position can be set to the same conditions. Thereby, the density values of the left adjustment position and the right adjustment position can be compared under the same conditions, and the light amounts of the lamps can be made more accurate and equal.

  According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the moving mechanism extends from the step on the left side to the reading line on which the image sensor at the left adjustment position reads in the sub-scanning direction. And the distance from the step on the right side to the reading line on which the image sensor reads at the right adjustment position is shorter than the distance between the reading line and the lamp as viewed from the sub-scanning direction. In addition, the reading unit is moved to the left adjustment position and the right adjustment position.

  According to this configuration, the moving mechanism includes the distance from the left step to the reading line that the image sensor reads at the left adjustment position, and the reading line that the image sensor reads from the right step to the right adjustment position. The reading unit is moved to the left adjustment position and the right adjustment position so that the distance up to is shorter than the distance between the reading line and the lamp as viewed from the sub-scanning direction. Thereby, the light from one lamp can be reliably blocked by the step. Therefore, it is possible to reliably recognize the presence or absence of a light amount difference (density value difference) between the lamps.

  According to a seventh aspect of the present invention, in the first to sixth aspects of the invention, the moving mechanism moves the reading unit to a plurality of different left adjustment positions and also reads the reading unit to a plurality of different right adjustment positions. The reading unit performs reading at each of the left adjustment position and the right adjustment position, and the density confirmation unit performs a main scanning direction on a plurality of lines read at each of the left adjustment positions. A density value of the left adjustment position is determined based on an average value of output values of a plurality of light receiving elements included in a predetermined number of light receiving element blocks in the sub-scanning direction, and a plurality of values read at the respective right adjustment positions For the line, the density value of the right adjustment position is determined based on an average value of output values of a plurality of light receiving elements included in a block of a predetermined number of light receiving elements in the main scanning direction and the sub scanning direction. It was decided to determine the amount of adjustment of the light amount of the light source so that the difference of each of the density values is eliminated.

  According to this configuration, the density confirmation unit includes a plurality of light receiving elements included in a predetermined number of light receiving element blocks in the main scanning direction and the sub scanning direction for the plurality of lines read at the respective left adjustment positions. A density value at the left adjustment position is determined based on the average value of the output values, and a plurality of lines read at each right adjustment position are included in a predetermined number of light receiving element blocks in the main scanning direction and the sub-scanning direction. The density value at the right adjustment position is determined based on the average value of the output values of the plurality of light receiving elements. Thus, by taking the average of a plurality of light receiving elements included in the light receiving element block, while reducing individual differences and variations in reading characteristics of each light receiving element (light receiving element), a difference in density value (light quantity difference) ) Can be recognized.

The invention according to claim 8 is the invention according to claims 1 to 6, wherein each lamp includes a rod-shaped light guide and two light sources at both ends of the light guide. For the two light sources on the near side when viewed from the main scanning direction, the output value of one light receiving element located on the near side of the center of the lamp when read at the left adjustment position, or a plurality of the light receiving elements The concentration value at the left adjustment position is determined based on the average value of the output values of the elements, and the output value of one light receiving element located on the front side of the center of the lamp when read at the right adjustment position, or The density value at the right adjustment position is determined based on the average value of the output values of the plurality of light receiving elements, the light amount adjustment amount of the light source on the near side is determined so that there is no difference between the density values, and the main scanning direction The left adjustment position for the light source on the back side The density value at the left adjustment position is determined based on the output value of one light receiving element located behind the center of the lamp when read, or the average value of the output values of a plurality of light receiving elements, The density at the right adjustment position based on the output value of one of the light receiving elements located at the back of the center of the lamp when read at the right adjustment position or the average value of the output values of the plurality of light receiving elements. A value is determined, and an adjustment amount of the light amount of the light source on the back side is determined so that there is no difference between the density values.

In a lamp in which light sources are provided at both ends of a light guide that emits light in the main scanning direction, more light from the light source provided on the near side is emitted on the front side as viewed from the main scanning direction (provided on the near side). The light source provided at the back side emits more light at the back side as viewed from the main scanning direction (the influence of the light source provided at the back side is strong). Therefore, according to this configuration, the density confirmation unit, for the two light sources on the near side as viewed from the main scanning direction, the light source on the near side so that there is no difference in density value between the two light sources on the near side. The light amount adjustment amount of the rear light source is determined so that there is no difference in density values between the two light sources on the rear side. Thereby, the light quantity of each light source provided at both ends of the lamp can be appropriately adjusted by the combination of the light sources on the near side and the back side .

  The invention according to claim 9 is the invention according to any one of claims 1 to 6, wherein each of the lamps includes a rod-shaped light guide and one light source at an end portion of the light guide. The density at the left adjustment position based on the output value of one light receiving element located at the center of the lamp when read at the left adjustment position or the average value of the output values of a plurality of light receiving elements A value is determined and read at the right adjustment position, based on the output value of one light receiving element located at the central portion of the lamp or the average value of the output values of a plurality of light receiving elements at the right adjustment position. The density value of the light source is determined, and the adjustment amount of the light amount of the light source is determined so that there is no difference between the density values.

In a lamp in which a light source is provided at one end of a light guide that emits light in the main scanning direction, whether or not the amount of light at the center position in the main scanning direction of the lamp is appropriate is one criterion. Therefore, according to this configuration, the density confirmation unit is based on the output value of one light receiving element located at the center of the lamp when read at the left adjustment position or the average value of the output values of a plurality of light receiving elements. Determine the density value at the left adjustment position, and adjust the right adjustment position based on the output value of one light receiving element located at the center of the lamp when read at the right adjustment position or the average value of the output values of a plurality of light receiving elements. The density value of the light source is determined, and the adjustment amount of the light amount of the light source is determined so that there is no difference between the density values. Thereby, the light quantity of each light source provided in one edge part of a lamp | ramp can be adjusted appropriately.

  According to a tenth aspect of the present invention, in the first to ninth aspects of the invention, the light amount adjustment amount of the light source is set according to a difference between the density value at the left adjustment position and the density value at the right adjustment position. A storage unit for storing the determined light amount adjustment table is included.

  According to this configuration, the storage unit that stores the light amount adjustment table that defines the light amount adjustment amount of the light source according to the difference between the density value at the left adjustment position and the density value at the right adjustment position is included. Thereby, by referring to the light amount adjustment table, it is possible to quickly and easily determine the adjustment amount for adjusting the light amount of the light source based on the difference in density value.

  The invention according to claim 11 includes the image reading device according to any one of claims 1 to 10.

  According to this configuration, in the image reading apparatus of the image forming apparatus, the light quantity of the lamps on both sides of the image sensor is adjusted so that the light quantity is equal, and the emphasis on the wrinkles and folds of the document is reduced, and the reading is performed. Image data with improved image quality can be obtained. Therefore, it is possible to provide an image forming apparatus that performs high-quality printing based on high-quality image data.

  The image processing apparatus according to any one of claims 1 to 10 includes a notification unit that notifies a message, and the notification unit is configured so that the density confirmation unit is in the left adjustment position even when adjustment is performed to increase the light amount of the light source. Based on the density value obtained by reading at the right adjustment position, when it is not recognized that the amount of light has increased, an abnormality of the lamp may be notified. Thereby, while being able to detect the failure of each lamp | ramp, a failure can be alert | reported to a user.

  Further, in the invention of claims 1 to 10, the light emission control unit may adjust the light amount of each light source by changing a duty ratio of a voltage applied to the light source or a supplied current. Thereby, the light quantity of the light source of a lamp can be adjusted.

  Alternatively, in the first to tenth aspects of the present invention, the light emission control unit may adjust the light amount of each light source by changing a voltage applied to the light source or a magnitude of a supplied current. Thereby, the light quantity of the light source of a lamp can be adjusted.

According to the present invention, so as to perform the adjustment of the uniformity of the lamp light quantity disposed on both sides of the image sensor, reducing the enhancement of wrinkle portions of the document, it is possible to improve the image quality in reading.

1 is a schematic front sectional view of a multifunction machine. 2 is a block diagram illustrating an example of a hardware configuration of a multifunction peripheral. FIG. It is a model front sectional view showing an example of an image reading device. It is a block diagram which shows an example of an image reading apparatus. (A) is sectional drawing of a reading part, (b) is explanatory drawing which shows an example of the structure of an image sensor. It is explanatory drawing which shows an example of a white reference board. It is a flowchart which shows an example of the flow of light quantity adjustment of each lamp. It is explanatory drawing which shows an example of the left adjustment position. It is explanatory drawing which shows an example of a right adjustment position. It is explanatory drawing which shows an example of a light quantity adjustment table. It is an example of the abnormality alerting | reporting screen of a lamp | ramp (light source). It is explanatory drawing which shows an example of the reading position of a white reference board. It is explanatory drawing for demonstrating the concept of the whole light quantity adjustment after the light quantity adjustment of a light source. It is explanatory drawing for demonstrating how to determine the density value in 2nd Embodiment. It is the schematic diagram which looked at the reading part in a 3rd embodiment from the upper part. It is the schematic diagram which looked at the reading part in a 4th embodiment from the upper part. It is explanatory drawing which shows an example of the light quantity adjustment table in 5th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. First, the first embodiment will be described with reference to FIGS. 1 to 13 by taking a multifunction peripheral 101 (image forming apparatus) as an example. However, each element such as configuration and arrangement described in each embodiment does not limit the scope of the invention and is merely an illustrative example.

(Outline of configuration of MFP 101)
First, an outline of a multifunction peripheral 101 including an image reading apparatus 100 according to the first embodiment will be described with reference to FIG. FIG. 1 is a schematic front sectional view of the multifunction machine 101.

  As shown in FIG. 1, a multifunction machine 101 according to the present embodiment includes an image reading apparatus 100 including a document cover 102 and an image reading unit 1 at an upper part (details will be described later). In addition, an operation panel 2 (illustrated by a broken line, corresponding to a notification unit) is provided on the front surface of the image reading unit 1, and a sheet feeding unit 3a, a conveyance path 3b, an image forming unit 4a, and a fixing unit 4b are provided in the main body of the multifunction machine 101. Etc. are provided.

  As shown in FIG. 1, the operation panel 2 is provided on the upper front side of the multifunction machine 101. The operation panel 2 includes a liquid crystal display unit 21 that displays the state of the multifunction machine 101 and various messages. The liquid crystal display unit 21 can display one or a plurality of keys for performing function selection, setting, character input, and the like. Further, a touch panel unit 22 (for example, a resistive film type) is provided on the upper surface of the liquid crystal display unit 21. The touch panel unit 22 is for extracting the position and coordinates of the portion pressed by the liquid crystal display unit 21. The operation panel 2 is also provided with various hard keys such as a start key 23 for instructing start of execution of various functions such as copying.

The paper feed unit 3a stores a plurality of sheets (for example, various sheets such as copy sheets, plain sheets, recycled sheets, thick sheets, and OHP sheets) and sends them one by one to the conveyance path 3b. The transport path 3b is a path for transporting paper from the paper feed unit 3a to the discharge tray 31. Then, the conveying path 3b is and the transport roller pair 32, 33 that rotates when the sheet conveying a sheet conveyed on standby in front of the image forming unit 4a, the paper combined toner image formation timing A pair of registration rollers 34 and the like are provided.

  The image forming unit 4a forms a toner image based on the image data, and transfers the toner image to the conveyed paper. Therefore, the image forming unit 4a includes a photosensitive drum 41 supported so as to be rotationally driven in the direction of the arrow shown in FIG. 1, and a charging device 42, an exposure device 43, and a developing unit disposed around the photosensitive drum 41. A device 44, a transfer roller 45, a cleaning device 46, and the like are provided.

  The toner image formation and transfer process will be described. The photoconductor drum 41 is provided substantially at the center of the image forming unit 4a and is driven to rotate in a predetermined direction. The charging device 42 charges the photosensitive drum 41 to a predetermined potential. In FIG. 1, an exposure device 43 outputs a laser beam based on image data, scans and exposes the surface of the photosensitive drum 41, and forms an electrostatic latent image corresponding to the image data. As the image data, image data obtained by the image reading unit 1, image data transmitted from an external computer 200 or a counterpart FAX apparatus 300 (see FIG. 5) connected by a network or the like is used.

  The developing device 44 supplies toner to the electrostatic latent image formed on the photosensitive drum 41 and develops it. The transfer roller 45 is pressed against the photosensitive drum 41 to form a nip. The sheet enters the nip while being timed according to the toner image. When the paper enters, a predetermined voltage is applied to the transfer roller 45, and the toner image on the photosensitive drum 41 is transferred to the paper. The cleaning device 46 removes the toner remaining on the photosensitive drum 41 after the transfer.

  The fixing unit 4b fixes the toner image transferred to the paper. The fixing unit 4b in the present embodiment is mainly composed of a heating roller 47 and a pressure roller 48 that incorporate a heating element. The heating roller 47 and the pressure roller 48 are pressed to form a nip. Then, as the sheet passes through the nip, the toner on the sheet surface is melted and heated, and the toner image is fixed on the sheet. The paper after the toner is fixed is received by the discharge tray 31. In this way, image formation (printing) is performed when the copy function and printer function are used.

(Hardware configuration of MFP 101)
Next, a hardware configuration of the multifunction machine 101 according to the first embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating an example of a hardware configuration of the multifunction machine 101.

  As illustrated in FIG. 2, the multifunction peripheral 101 according to the present embodiment includes a main control unit 5 therein. The main control unit 5 controls the entire multifunction machine 101. For example, the main control unit 5 includes a CPU 51, a storage unit 52, and the like.

  The CPU 51 is a central processing unit, and controls and performs each unit of the multifunction machine 101 based on a control program stored in the storage unit 52 and developed. The storage unit 52 includes a storage device such as a ROM, a RAM, an HDD, or a flash ROM. The storage unit 52 stores a control program, control data, setting data, image data scanned by the image reading unit 1, and the like of the multifunction machine 101.

  The main control unit 5 is connected to the image reading apparatus 100 (image reading unit 1) and the sheet feeding unit 3a, the conveyance path 3b, the image forming unit 4a, the fixing unit 4b, the operation panel 2 and the like in the multifunction machine 101. Based on the control program and data in the storage unit 52, the operation of each unit is controlled so that image formation is performed appropriately.

  Further, the main control unit 5 is connected to an I / F unit 53 including various connectors, sockets, a communication control chip, and the like. The I / F unit 53 communicatively connects the computer 200 (for example, a personal computer or a server), the other party's FAX apparatus 300, and the multifunction machine 101 via a network, a cable, a public line, or the like. For example, image data including setting data and the like can be transmitted and received (scanner function, FAX function) to / from external computer 200 or counterpart FAX apparatus 300 (Internet FAX may be used). In addition, image data from the external computer 200 or the counterpart FAX apparatus 300 can be stored in the storage unit 52 or printed (printer function, FAX function).

(Outline of the image reading apparatus 100)
Next, the image reading apparatus 100 according to the first embodiment will be described with reference to FIG. FIG. 3 is a schematic front sectional view showing an example of the image reading apparatus 100.

  An image reading apparatus 100 according to the present embodiment is included in a multifunction machine 101. Therefore, FIG. 3 is an enlarged view of only the document cover 102 and the image reading unit 1 in the multifunction machine 101 extracted. The document cover 102 can be lifted upward by a fulcrum (not shown) provided on the far side in the direction perpendicular to the paper surface of FIG. Then, the user opens the document cover 102 and places the document on the contact glass 11. Thereafter, the user closes the document cover 102 and presses the document with the document cover 102.

  Next, the image reading unit 1 will be described. The image reading unit 1 includes a transparent plate-like contact glass 11 on the upper surface. The image reading unit 1 irradiates the document placed on the contact glass 11 with light, reads the document based on the reflected light, and generates image data.

  In order to read the original, the image reading unit 1 includes a CIS (Contact Image Sensor) type reading unit 6 (details of the reading unit 6 will be described later). The reading unit 6 is provided below the contact glass 11.

  The reading unit 6 is connected to a winding drum 13 (corresponding to a moving mechanism) by a wire 12 (corresponding to a moving mechanism). The take-up drum 13 is rotated by a take-up motor 14 that rotates forward and backward (refer to FIG. 4, corresponding to a moving mechanism), and the reading unit 6 can be moved freely in the horizontal direction (the left-right direction of the multifunction machine 101). it can. Note that a plurality of wires 12 are connected to the reading unit 6, and the plurality of wires 12 are laid around in the image reading unit 1. In FIG. 3, only one wire 12 is shown for convenience. .

When reading the document on the contact glass 11, the reading unit 6 is moved in the horizontal direction by the rotational drive of the winding drum 13. In addition, instead of the document cover 102, the image reading apparatus 100 (multifunction machine 101) according to the present embodiment may be equipped with a document conveying apparatus that automatically and continuously conveys documents one by one to a reading position. . Then, a feed reading contact glass 15 is provided on the left side of the contact glass 11 at a distance from the contact glass 11. When the document transport device is attached, the document transported by the document transport device passes over the feed reading contact glass 15 . The reading unit 6 reads a document that passes through the feed reading contact glass 15 .

Here, a guide member 16 is provided between the contact glass 11 and the feed reading contact glass 15 . On the upper surface of the guide member 16, a reference position and paper size for placing a document on the contact glass 11 are written. The guide member 16 also has a function of guiding document conveyance when a document conveyance device is provided. A white reference plate 7 for obtaining a white reference is provided below the guide member 16. The white reference plate 7 is a plate extending in the main scanning direction of the image reading apparatus 100 (a direction perpendicular to the document conveyance direction, a direction perpendicular to the paper surface of FIG. 3). The white reference plate 7 has a convex portion 71 directed downward (details of the white reference plate 7 will be described later).

(Hardware configuration of image reading apparatus 100 and flow of image data)
Next, based on FIG. 4, the hardware configuration of the image reading apparatus 100 according to the first embodiment and the generation of image data will be described. FIG. 4 is a block diagram illustrating an example of the image reading apparatus 100. In FIG. 4, the flow of image data is indicated by white arrows.

  The image reading unit 1 that is a part of the image reading apparatus 100 is provided with a reading control unit 10 (corresponding to a density confirmation unit). The reading control unit 10 is a substrate on which various electronic components such as a CPU and a chip are mounted. Note that a storage unit 10 a can be provided in the reading control unit 10. The storage unit 10a stores, for example, a program and data for controlling the image reading apparatus 100. The reading control unit 10 is communicably connected to the main control unit 5 of the MFP 101 main body. When reading a document such as when the start key 23 of the operation panel 2 is pressed, the main control unit 5 gives a document reading instruction to the reading control unit 10. The reading control unit 10 receives an instruction from the main control unit 5 and controls the image reading apparatus 100. In the reading control unit 10, a light emission control unit 10 b that controls turning on and off of each light source 80 of each lamp 8 of the reading unit 6 and controlling the amount of light is provided. The light emission control unit 10 b is a circuit that supplies current to each light source 80. Note that the light emission control unit 10 b may be provided outside the reading control unit 10.

  In the present embodiment, the light emission control unit 10b adjusts the amount of light by controlling the turn-on time and turn-off time of each light source 80. Specifically, the light emission control unit 10b individually generates a PWM signal for each light source 80, adjusts the duty ratio of the PWM signal (the ratio of the on time to turn on and the off time to turn off), and the light amount of each light source 80 Adjust and control. Therefore, the light emission control unit 10b of the present embodiment includes a plurality of PWM circuits.

  When reading a document, the reading control unit 10 operates the reading unit 6. The reading unit 6 includes a plurality of lamps 8 (left lamp 8L and right lamp 8R) and an image sensor 9 (details will be described later). Specifically, when reading a document, the reading control unit 10 lights each lamp 8 of the reading unit 6 and drives the image sensor 9. Further, the reading control unit 10 controls a winding motor 14 that rotates the winding drum 13.

  Note that the image sensor 9 of the present embodiment can read in black and white. Therefore, the image sensor 9 includes a Bk / W (monochrome reading) line sensor. The image sensor 9 may further include, for example, three line sensors of R (for red), G (for green), and B (for blue) in order to support color reading. .

The output of the image sensor 9 of the reading unit 6 is input to the processing unit 17. The processing unit 17 includes, for example, an A / D conversion unit 17a, a reference value holding unit 17b, a correction unit 17c, an image memory 17d, and the like. The processing unit 17 includes various types of electronic circuits and circuits dedicated to image processing such as ASICs and memories. Each light receiving element 90 of the image sensor 9 photoelectrically converts the reflected light, accumulates electric charge according to the level of the reflected light (light reception amount), and discharges the electric charge at a certain timing. In other words, each light receiving element 90 outputs a voltage (current) corresponding to the intensity of the reflected light. The image sensor 9 outputs an analog output (for example, voltage) from each light receiving element 90 of the line sensor to the processing unit 17. In some cases, an amplification unit that amplifies the output of each light receiving element 90 may be provided inside and outside the image sensor 9. In this case, the processing unit 17 receives the amplified voltage value as an output value from each light receiving element 90.

  The A / D conversion unit 17a of the processing unit 17 converts the analog output (analog output voltage) of each light receiving element 90 into a digital value (hereinafter, the converted digital value is referred to as “output value”). The digital output value obtained by converting the analog output of each light receiving element 90 is used to determine the density value in the present invention (details will be described later).

  Further, in consideration of variations in sensitivity of each light receiving element 90 and unevenness of light irradiated to the original depending on the position in the main scanning direction, the digital output value of each light receiving element 90 is gradationized and determined in advance. In order to obtain a pixel value having a number of bits (for example, 8 to 10 bits), a reference value holding unit 17b for storing a white reference value and a black reference value is provided. When a plurality of line sensors are provided, the reference value holding unit 17b holds a white reference value and a black reference value for each color line sensor.

  Here, the black reference value and the white reference value in gradation to pixel values will be described. First, acquisition of the white reference value and the black reference value will be described. The reading control unit 10 causes the reading unit 6 to perform reading before document reading, after the main power is turned on, or when returning from the power saving mode, and causes the reference value holding unit 17b to hold the black reference value and the white reference value.

  In the present embodiment, the reading control unit 10 outputs the output value (output voltage value) of each light receiving element 90 of the image sensor 9 with each lamp 8 (left lamp 8L and right lamp 8R) turned off. The black reference value of 90 is stored in the reference value holding unit 17b. In other words, the reference value holding unit 17b acquires a digital value obtained by converting the analog output voltage from each light receiving element 90 when each lamp 8 is extinguished by the A / D conversion unit 17a, and uses it as a black reference value for each light receiving element 90. Remember. Specifically, the reference value holding unit 17b acquires several lines of output values of each light receiving element 90 when each lamp 8 is turned off, averages the output values for each light receiving element 90, and reduces the influence of noise. Thus, the black reference value of each light receiving element 90 is obtained.

  Further, the reading control unit 10 turns on the lamps 8 (the left lamp 8L and the right lamp 8R), and outputs the output values (output voltage values) of the light receiving elements 90 of the image sensor 9 when the pure white reference plate 7 is read. ) As a white reference value of each light receiving element 90 in the reference value holding unit 17b. In other words, the reference value holding unit 17b obtains a digital value obtained by converting the analog output voltage from each light receiving element 90 when the white reference plate 7 is read by turning on each lamp 8, and converted by the A / D conversion unit 17a. And stored as the white reference value of each light receiving element 90. Specifically, the reference value holding unit 17b acquires several lines of output values of each light receiving element 90 when reading the white reference plate 7, averages the output values for each light receiving element 90, and influences noise. The white reference value of each light receiving element 90 is obtained by reducing.

  Then, the reference value holding unit 17b of the processing unit 17 gives the white reference value and the black reference value to the correction unit 17c for each light receiving element 90 of each image sensor 9 of the reading unit 6. Then, the correction unit 17c, for each light receiving element 90 (each light receiving element 90), between the white reference value and the black reference value with a predetermined number of steps (the number of gradations, for example, 8-bit 256 gradations). Grading is performed in accordance with the magnitude of the output value from each light receiving element 90 (each light receiving element 90). For example, when the processing unit 17 outputs monochrome image data, the output value of one light receiving element 90 is output in 8 bits (256 gradations), and the value of each light receiving element 90 (pixel) is a value indicating the density. Become. In the case of color, the processing unit 17 gradations the output value of one light receiving element 90 in RGB to a total of 24 bits (for example, Red = 8 bits, Green = 8 bits, Blue = 8 bits, 0 to 0 respectively). It takes a value of 255 and 256 gradations). If the output value from each light receiving element 90 input to the processing unit 17 does not fall between the white reference value and the black reference value, for example, the maximum value in gray scale (if it is pure white, for example, 256 gray scales). 255) or the minimum value (black, for example, 0). Thereby, image data of the document is obtained.

  In addition, the correction unit 17c performs various corrections on the image data, such as γ correction, unevenness in the light amount distribution of each lamp 8, and individual distortion of each light receiving element 90, such as correction of distortion depending on the position of the light receiving element 90. You may make it apply to.

  The image data processed by the correction unit 17c is stored in the image memory 17d. The image memory 17d outputs image data to the storage unit 52 (for example, RAM) on the main body side, for example, in document page units or block units (band units) on a strip obtained by dividing the document page into a plurality of pages.

  The image data stored in the storage unit 52 is input to the image processing unit 54 of the main body. The image processing unit 54 according to the present embodiment is a circuit configured by combining calculation related to image data, a work RAM as a work area, an ASIC as a dedicated circuit, and the like. Note that the image processing program 54 can also be realized by software by storing an image processing program in the CPU 51 or the storage unit 52 of the main control unit 5.

  The image processing unit 54 can perform various types of image processing such as density conversion processing, enlargement / reduction processing, and data format (file format) conversion processing of image data. However, since image processing that can be performed is diverse, in this description, the image processing unit 54 can perform known image processing, and a detailed description of image processing that can be performed by the image processing unit 54 is omitted.

  Then, the image data after the image processing unit 54 performs the image processing is sent to, for example, the exposure device 43 of the image forming unit 4a and used for scanning / exposure of each photosensitive drum 41. Thus, printing can be performed based on the original (copy function). Further, for example, the image data after the image processing unit 54 performs image processing can be sent to the storage unit 52 and stored in the storage unit 52 (scanner function). Alternatively, the image data after the image processing unit 54 performs image processing can be transmitted to the external computer 200 or the FAX apparatus 300 via the I / F unit 53 (transmission function).

  Note that the operation panel 2 can display and notify information regarding the image reading apparatus 100 included in the multifunction peripheral 101. Therefore, the operation panel 2 functions not only as the multifunction machine 101 but also as a notification unit of the image reading apparatus 100.

(Reading unit 6)
Next, the reading unit 6 according to the first embodiment will be described with reference to FIG. FIG. 5A is a cross-sectional view of the reading unit 6, and FIG. 5B is an explanatory diagram illustrating an example of the structure of the image sensor 9.

  First, the reading unit 6 is provided with a housing 61 having a substantially U-shaped cross section. The casing 61 has a box shape with the direction perpendicular to the paper surface of FIG. The longitudinal direction of the housing 61 is the main scanning direction of the reading unit 6. A plate-like glass 62 is attached to the upper surface of the housing 61 so as to close the opening on the upper surface of the housing 61.

  An image sensor 9 extending in the direction perpendicular to the paper surface (main scanning direction) in FIG. The image sensor 9 is a line sensor in which a plurality of light receiving elements 90 (photoelectric conversion elements) are arranged along the main scanning direction. In the reading unit 6 of the present embodiment, the image sensor 9 is longer than the short side of the A3 size paper so that the A3 size paper can be read.

  Here, an example of the structure of the image sensor 9 will be described with reference to FIG. The image sensor 9 includes a line sensor in which a plurality of light receiving elements 90 are arranged in a row. The image sensor 9 includes a plurality of line sensors in the case of color reading. The number and size of each light receiving element 90 depends on the reading resolution. For example, a read register 91 is provided for each light receiving element 90. The read register 91 sequentially outputs the outputs of the light receiving elements 90 to the outside with a constant clock.

  Above the image sensor 9, a rod lens array 63 is provided as a lens. The rod lens array 63 includes a plurality of rod lenses 63 a arranged in the main scanning direction, and guides reflected light of the document to the image sensor 9.

  Light guides 81 are provided on both sides of the rod lens array 63, respectively. As indicated by broken lines in FIG. 5A, light sources 80 are provided at the front and back end portions of the casing 61 in the direction perpendicular to the paper surface of each light guide 81 (the light source 80 on the front side is invisible). ). Accordingly, two light sources 80 are provided at each of the longitudinal ends of the light guide 81 of the reading unit 6 (four in total) (see FIG. XX). Here, in the present embodiment, each light source 80 is an LED.

  One lamp 8 includes one light guide 81 and light sources 80 at both ends of the light guide 81. The lamps 8 are provided on the left side (left lamp 8L) and the right side (right lamp 8R) of the image sensor as viewed from the main scanning direction.

The light guide 81 guides light emitted from the light source 80 in the longitudinal direction (main scanning direction) of the light guide 81. Further, the light guide 81 is a rod lens so that the light quantity level is substantially uniform at each position in the longitudinal direction (main scanning direction) of the reading unit 6 as indicated by a two-dot chain line arrow in FIG. Light is emitted above the array 63 (above the glass 62). Each rod lens 63a included in the rod lens array 63 collects the light reflected by the reading target (for example, the document or the white reference plate 7) and guides it to the image sensor 9 (an example of the direction of the reflected light). (Indicated by a two-point difference line with an arrow).

(White reference plate 7)
Next, an example of the white reference plate 7 according to the first embodiment will be described with reference to FIG. FIG. 6 is an explanatory diagram showing an example of the white reference plate 7.

  In the image reading apparatus 100 of the present embodiment, the white reference plate 7 is provided below the guide member 16. As shown in FIG. 6, the white reference plate 7 of the present embodiment has a convex portion 71 unlike the conventional white reference plate 7. 6 is a view of the white reference plate 7 viewed from below. The lower part of FIG. 6 is a cross-sectional view taken along line A-A ′ of the upper part.

  The length of the white reference plate 7 in the main scanning direction is equal to or slightly longer than the length of the image sensor 9 in the main scanning direction. And the convex part 71 is provided in the white reference | standard board 7 from one edge part of the main scanning direction (longitudinal direction) to the other edge part. The protrusion 71 forms two steps 72 when viewed from the main scanning direction (hereinafter, the left step 72L is referred to as “left step 72L” and the right step 72R is referred to as “right step 72R”).

(Flow of light intensity adjustment for each lamp 8)
Next, an example of the flow of light amount adjustment of each lamp 8 in the image reading apparatus 100 according to the first embodiment will be described with reference to FIGS. FIG. 7 is a flowchart illustrating an example of the flow of light amount adjustment of each lamp 8. FIG. 8 is an explanatory diagram illustrating an example of the left adjustment position. FIG. 9 is an explanatory diagram illustrating an example of the right adjustment position. FIG. 10 is an explanatory diagram showing an example of the light amount adjustment table T1. FIG. 11 is an example of the abnormality notification screen S1 of the lamp 8 (light source 80). FIG. 12 is an explanatory diagram showing an example of the reading position of the white reference plate 7. FIG. 13 is an explanatory diagram for explaining the concept of overall light amount adjustment after light amount adjustment of the light source 80.

  In the image reading apparatus 100 of the present embodiment, the reading unit 6 is provided with two lamps 8, a left lamp 8L and a right lamp 8R. If there is a difference in the amount of light between the two lamps 8, the two lamps 8 cannot uniformly illuminate the wrinkles or folds of the document, and wrinkles or creases appear in the image data as a result of reading. End up. Therefore, in the image reading apparatus 100 and the multifunction peripheral 101 of the present embodiment, the white reference plate 7 having the step 72 is read so that the light quantity of each lamp 8 (the left lamp 8L and the right lamp 8R) is adjusted to be uniform. can do.

  Here, the adjustment (light amount adjustment) for making the light amount of each lamp 8 uniform is performed, for example, at the time of factory shipment of the multifunction peripheral 101 or during maintenance after the multifunction peripheral 101 is installed. Alternatively, the user may be able to adjust the light quantity uniformity at an arbitrary time.

  In order to adjust the light amount of each lamp 8 (left lamp 8L and right lamp 8R), the operation panel 2 is operated to instruct execution of the light amount adjustment of each lamp 8. Thereby, the light quantity adjustment of each lamp 8 is started. The start point of the light amount adjustment of each lamp 8 is the start of FIG.

  When the light amount adjustment of each lamp 8 is started, the reading control unit 10 reads data (light amount data) indicating the light amount of each light source 80 from the storage unit 10a (step # 1). In the present embodiment, the light amount of each light source 80 (LED) is adjusted by PWM, so that each light amount data becomes the frequency of the PWM signal (not necessary when the frequency is fixed) and the duty ratio. When the light amount adjustment is performed for the first time, or when the light amount adjustment is not changed from the default value, the light amount data for each light source 80 is a predetermined default value. In the second and subsequent light amount adjustments, the light source 80 whose light amount has been changed is the light amount data set (corrected) in the previous adjustment.

  Next, the reading control unit 10 controls the winding motor 14 to move the reading unit 6 to the left adjustment position (step # 2). The left adjustment position is a position where a line (reading line) read by the image sensor 9 is positioned on the left side of the left step 72 </ b> L of the white reference plate 7. Then, the reading control unit 10 lights each light source 80 on the light emission control unit 10b based on the light amount data read from the storage unit 10a, and causes the image sensor 9 of the reading unit 6 to perform reading at the left adjustment position (step # 3). ).

Here, reading at the left adjustment position will be described with reference to FIG. As shown in FIG. 8, when the reading line of the image sensor 9 is left outer side than the step 72 L (when the left adjustment position), the light emitted from the right lamp 8R is against the protrusion 71 of the white reference plate 7 Reflected. Therefore, the light emitted from the right lamp 8R is difficult to reach the image sensor 9. The light received by the image sensor 9 is dominantly emitted from the left lamp 8L (an example of light emitted by a broken line is illustrated).

  Then, the reading control unit 10 causes the A / D conversion unit 17a to convert the analog output voltage of each light receiving element 90 of the image sensor 9 in reading at the left adjustment position into a digital value (step # 4). Then, the reading control unit 10 determines the density value at the left adjustment position based on the output value of each light receiving element 90 that has become a digital value (step # 5).

  Here, the reading control unit 10 may determine the output value of any one of the plurality of light receiving elements 90 at a predetermined position as a density value indicating the density at the left adjustment position. Alternatively, the reading control unit 10 determines an average value of output values of a plurality of light receiving elements 90 at predetermined positions among the light receiving elements 90 of the image sensor 9 as a density value indicating the density at the left adjustment position. Also good. Here, when taking the average of the output values, the reading control unit 10 may obtain the average of the output values of all the light receiving elements 90 for one line in the main scanning direction to determine the density value, for example, in the main scanning direction. The density value may be determined by obtaining an average value of the output values of a plurality of (for example, about 1 to 10) light receiving elements 90 at the central position.

  Next, the reading control unit 10 controls the winding motor 14 to move the reading unit 6 to the right adjustment position (step # 6). The right adjustment position is a position where a line (reading line) read by the image sensor 9 is positioned on the right side of the right step 72R of the white reference plate 7. Then, the reading control unit 10 turns on each light source 80 based on the data indicating the light amount read from the storage unit 10a, and causes the image sensor 9 of the reading unit 6 to perform reading at the right adjustment position (step # 7).

Similarly to FIG. 8, reading at the right adjustment position will be described with reference to FIG. As shown in FIG. 9, when the reading line of the image sensor 9 is on the right outside of the step 72 R (when the right adjustment position is reached), the light emitted from the left lamp 8L hits the convex portion 71 of the white reference plate 7. Reflected. Therefore, the light emitted from the left lamp 8L becomes difficult to reach the image sensor 9. The light received by the image sensor 9 is dominantly emitted from the right lamp 8R (an example of light emitted by a broken line is illustrated).

  Then, the reading control unit 10 causes the A / D conversion unit 17a to convert the analog output voltage of each light receiving element 90 (each light receiving element 90) of the image sensor 9 in reading at the right adjustment position into a digital value (step # 8). ). Then, the reading control unit 10 determines the density value at the right adjustment position based on the output value of each light receiving element 90 that has become a digital value (step # 9).

  Here, the reading control unit 10 determines the density value at the right adjustment position in the same manner as the density value at the left adjustment position. When the output value of one of the light receiving elements 90 at a predetermined position is determined as a density value indicating the density at the left adjustment position, the reading control unit 10 performs the left adjustment according to the reading at the right adjustment position. The output value of one light receiving element 90 at the same position (predetermined position) as the position is determined as the density value at the right adjustment position.

  Alternatively, when the average value of the output values of the plurality of light receiving elements 90 at a predetermined position is determined as the density value indicating the density at the left adjustment position, the reading control unit 10 responds to the reading at the right adjustment position. The average value of the output values of the plurality of light receiving elements 90 at the same position (predetermined position) as in the left adjustment position is determined as the density value at the right adjustment position. Thereby, the density value of the left adjustment position and the density value of the right adjustment position to be compared are obtained by the same standard and method.

  Then, the reading control unit 10 compares the density values and recognizes the density value difference (step # 10). Specifically, as the amount of light received by the light receiving element 90 increases, the amount of stored charge increases, and thus the output value of each light receiving element 90 increases. On the other hand, the smaller the amount of received light, the smaller the output value. Therefore, the reading control unit 10 can recognize which lamp 8 is darker or brighter depending on the density value at the left adjustment position and the density value at the right adjustment position. In addition, the difference in the amount of light can be recognized from the difference in density value between the left adjustment position and the right adjustment position.

  Here, in order to compare the density values based on the same reference, the reading control unit 10 controls the winding motor 14 so that the distance d1 from the left step 72L to the reading line at the left adjustment position and the right step 72R. The reading unit 6 may be moved to the left adjustment position and the right adjustment position with the same distance (distance d1 = distance d2) from the distance d2 to the reading line at the right adjustment position (see FIGS. 8 and 9).

  Further, the reading control unit 10 determines the distance from the left step 72L to the reading line at the left adjustment position in the sub-scanning direction so that the light of one lamp 8 is reliably blocked by the convex portion 71 of the white reference plate 7. d1 and the distance d2 from the right step 72R to the reading line at the right adjustment position are shorter than the distance d3 between the reading line and the lamp 8 when viewed from the sub-scanning direction (distance d1 <distance d3, distance d2 < The distance d3) and the reading unit 6 may be moved to the left adjustment position and the right adjustment position (see FIGS. 8 and 9).

  Next, the reading control unit 10 determines the light amount adjustment amount based on the difference between the density values of the left adjustment position and the right adjustment position, corrects the light amount data of the light source 80 of the darker lamp 8, and the corrected data. Is stored in the storage unit 10a (step # 11).

  Specifically, the reading control unit 10 corrects the light amount of the light source 80 of the darker lamp 8 to increase. For the amount of light to be increased, the reading control unit 10 determines how much the duty ratio of the light source 80 that increases the amount of light is increased based on the difference in density value (determines an adjustment amount). For example, as shown in FIG. 10, a light amount adjustment table T1 in which a duty ratio to be increased with respect to the difference in density value is stored in the storage unit 10a. Then, the reading control unit 10 refers to the light amount adjustment table T1 and adjusts the duty ratio of the PWM signal to be increased by the light source 80 that increases the light amount according to the difference in density value between the left adjustment position and the right adjustment position. Determine as quantity.

  If there is no difference in density value, or there is a difference, it may be acceptable and may be a slight difference. Therefore, the light amount adjustment table T1 also defines a case where the light amount data is not corrected even if there is a difference in density value. In other words, when the difference between the density values of the left adjustment position and the right adjustment position falls within a predetermined tolerance, the reading control unit 10 does not correct data indicating the light amount of the light source 80.

Next, the reading control unit 10 detects a failure of the lamp 8 (step # 12). This failure detection is performed when the light amount of the light source 80 is increased. Specifically, Step # 2 to Step # 10 are performed in a state where the corrected light amount data is used and the light amount is adjusted to be uniform. Then, the reading control unit 10 compares the density value difference between the right adjustment position and the left adjustment position before correction of the light amount data with the difference between the density value values of the right adjustment position and the left adjustment position after the light amount correction. Check if the difference in values is small. Alternatively, the reading control unit 10 moves the reading unit 6 to a position where the light of the lamp 8 that has increased the amount of light is dominant in the winding motor 14, compares the density value before and after correction, and the amount of light is You may confirm whether it increased.

  If the light amount of the lamp 8 that should have increased the light amount has not increased despite the light amount adjustment (even though the light amount data has been corrected), the reading control unit 10 has failed the light source 80 of the lamp 8. Is detected. On the other hand, if an increase in the light amount of the lamp 8 (light source 80) that has increased the light amount is recognized according to the light amount adjustment (according to the correction of the light amount data), the reading control unit 10 has failed in the light source 80 of the lamp 8. Recognize not.

  Here, if the reading control unit 10 detects a failure of the lamp 8 (light source 80), the reading control unit 10 notifies the abnormality of the lamp 8 (light source 80). Specifically, as illustrated in FIG. 11, the reading control unit 10 displays an abnormality notification screen S1 for notifying abnormality of the lamp 8 (light source 80). For example, as shown in FIG. 11, the reading control unit 10 displays the fact that there is an abnormality in the lamp 8 of the reading unit 6 and the necessity for replacement or inspection, and causes the operation panel 2 to notify.

Then, the read control unit 10 controls the take-up motor 14, a position of the reading unit 6 reads the convex portion 71 of the white reference plate 7 (reading line is between the step 72 L and the step 72 R position) (Step # 13). Then, the reading control unit 10 turns on the light sources 80 of the left lamp 8L and the right lamp 8R with the light amount after the light amount adjustment (after correcting the light amount data), and causes the image sensor 9 of the reading unit 6 to perform reading. (Step # 14).

  Here, the movement of the reading unit 6 will be described. For example, a reference position sensor 18 for detecting whether or not the reading unit 6 is at the reference position (home position) is provided in the image reading unit 1 (see FIG. 4). The reference position sensor 18 is an optical sensor, for example, and the output of the reference position sensor 18 is input to the reading control unit 10. For example, the reference position of the reading unit 6 is set below the white reference plate 7.

Based on the output of the reference position sensor 18, the reading control unit 10 recognizes whether the reading unit 6 is at the reference position. When the reading of the original is completed, the reading unit 6 controls the winding motor 14 to retract the position of the reading unit 6 to the reference position. And, the storage unit 10a, the reference position from to the left adjustment position, the reference position from to the right adjustment position, the take-up motor from the reference position to a position for reading between the step 72 L and the step 72 R of the white reference plate 7 14 Is stored (for example, the number of pulses to be input to the motor). Thus, the read control unit 10, and the right adjustment position by controlling the take-up motor 14, the left adjustment position or, the white reference plate 7 the step 72 L and the step 72 accurately reading unit 6 in a position to read between R Can be moved.

Then, the reading control unit 10 causes the A / D conversion unit 17a to convert the analog output voltage of each light receiving element 90 of the image sensor 9 in reading by the convex portion 71 of the white reference plate 7 into a digital value (step # 15). ). Then, the reading control unit 10 among the light receiving elements 90 of the image sensor 9 outputs an output value of one light receiving element 90 at a predetermined position in the main scanning direction or an average of output values of a plurality of light receiving elements 90. The value is determined as a reference value (step # 16). Here, the reading control unit 10 may determine the average value of the output values of all the light receiving elements 90 for one line in the main scanning direction as a reference value. For example, a plurality of (for example, a plurality of central positions in the main scanning direction (for example, The average value of the output values of the light receiving elements 90 (about 1 to 10) may be obtained and defined as the reference value.

  Then, the reading control unit 10 performs final light amount adjustment with respect to the total light amount of each lamp 8 based on the reference value (step # 17).

  When the light amount of the light source 80 of one lamp 8 is increased, the light amount of the left lamp 8L and the light amount of the right lamp 8R can be made uniform. However, the total light quantity of the left lamp 8L and the right lamp 8R that are made uniform is not always appropriate. If the total amount of light is too large, whiteout may occur when a document is read. If the total amount of light is too small, black crushing may occur. Therefore, in the light amount adjustment of each lamp 8, final light amount adjustment is performed with respect to the total light amount of each lamp 8 after the light amount correction of the light source 80 (step # 17).

  Here, an example of the final light amount adjustment will be described with reference to FIG. First, in reading, an allowable range indicating a reference value range when whiteout or blackout is difficult to occur is determined in advance. The allowable range is obtained by experiments or the like as a reference value range when appropriate reading can be performed. Data indicating an allowable range (an appropriate range of the total light amount of each lamp 8) is stored in, for example, the storage unit 10a.

  The reading control unit 10 reads data indicating the allowable range from the storage unit 10a and compares it with the obtained reference value. As shown in FIG. 13, if the obtained reference value falls below the allowable range, it can be said that the light amount is insufficient as a whole. Therefore, the reading control unit 10 corrects the data indicating the light amounts of all the light sources 80 so that the light amounts of the respective light sources 80 are increased. On the other hand, if the obtained reference value exceeds the allowable range, it can be said that the amount of light is excessive (too much) as a whole. Therefore, the reading control unit 10 corrects data indicating the light amounts of all the light sources 80 so that the light amounts of the respective light sources 80 are reduced.

  For the amount of light to be increased or decreased for each light source 80, the reading control unit 10 determines how much the duty ratio of each light source 80 is based on the difference between the reference value and the median value of the allowable range (which may be an upper limit value or a lower limit value). Decide whether to increase or decrease. For example, a table in which the duty ratio to be increased / decreased per light source 80 with respect to the difference between the reference value and the median value of the allowable range is stored in the storage unit 10a. Then, the reading control unit 10 refers to the table and corrects the light source 80 by equally increasing / decreasing the duty ratio, and stores the corrected duty ratio of each light source 80 in the storage unit 10a.

  If the white reference plate 7 is provided with a step 72, the light of one of the lamps 8 (the left lamp 8L and the right lamp 8R) is reflected by the convex portion 71 and can be read so as not to reach the image sensor 9. It becomes possible. Therefore, the image reading apparatus 100 (multifunction machine 101) according to the present embodiment includes the image sensor 9 in which a plurality of light receiving elements 90 are arranged in the main scanning direction, and the main scanning direction as the longitudinal direction and the image sensor 9 in the sub scanning direction. And two lamps 8 (left lamp 8L and right lamp 8R) each having a light source 80. When reading a document, each light source 80 is turned on and read by the image sensor 9. , A moving mechanism (winding motor 14, winding drum 13, wire 12, etc.) that moves the reading unit 6 in the sub-scanning direction, and a light emission control unit that controls light emission of the light source 80 of each lamp 8. 10b, a white reference plate 7 provided on the moving path of the reading unit 6 and provided above the reading unit 6, having a downward convex portion 71, and provided with a step 72, and an image A density confirmation unit (reading control unit 10) that determines a density value that is a value indicating density based on the output value of each light receiving element 90 of the sensor 9, and the moving mechanism is configured such that the image sensor 9 moves from the left step 72L to the white level. The reading unit 6 is moved to the left adjustment position for reading the position separated in the left outer direction of the reference plate 7 and the right adjustment position for the image sensor 9 to read the position separated in the right outer direction of the white reference plate 7 from the right step 72R. The reading unit 6 is moved to the position where the reading unit 6 performs reading at the left adjustment position and the right adjustment position, and the density confirmation unit reads the density value obtained by reading at the left adjustment position and the reading at the right adjustment position. The light amount adjustment amount of the light source 80 is determined so that the obtained density value difference is eliminated, and the light emission control unit 10b adjusts the light amount of the light source 80 based on the adjustment amount.

  As a result, the difference in the amount of light (difference in density value) between the two lamps 8 (left lamp 8L, right lamp 8R) is recognized using the image sensor 9 that the image reading apparatus 100 originally has, without installing a separate sensor. be able to. Then, the light emission control unit 10b adjusts the light amount of the light source 80 so that there is no difference in density value. Accordingly, since the light amounts of the lamps 8 on both sides of the image sensor 9 are adjusted so that the light amounts are equal, emphasis on the wrinkles and folds of the document can be reduced and the image quality in reading can be improved.

  When the density confirmation unit (reading control unit 10) recognizes that the reading at the left adjustment position is darker, the light amount of the light source 80 of the left lamp 8 (left lamp 8L, right lamp 8R) is increased. An adjustment amount is determined, and when the density confirmation unit (reading control unit 10) recognizes that the reading at the right adjustment position is darker, the adjustment amount is determined so as to increase the light amount of the light source 80 of the right lamp 8. Thereby, the light quantity of the lamps 8 on both sides of the image sensor 9 can be adjusted so that the light quantity becomes equal while securing the total light quantity of the lamps 8 (left lamp 8L, right lamp 8R) on both sides.

  Further, the density confirmation unit (reading control unit 10) determines the density value at the left adjustment position based on the output value of one light receiving element 90 or the average value of the output values of the plurality of light receiving elements 90 when read at the left adjustment position. And the density value at the right adjustment position is determined based on the output value of one light receiving element 90 or the average value of the output values of the plurality of light receiving elements 90 when read at the right adjustment position. Thus, if the density value is determined based on the output value of one light receiving element 90, the density value at each adjustment position and the difference between the density values (difference in the amount of light) can be obtained with extremely simple processing. Alternatively, the density value is determined by taking the average of the output values of the plurality of light receiving elements 90 to reduce individual differences and variations in the reading characteristics of each light receiving element 90, while reducing the difference in density value (difference in light amount). Can be recognized.

  If the total amount of light from the lamps 8 (the left lamp 8L and the right lamp 8R) is too large, a portion that is brighter than a certain level may be read in almost white (out-of-white). Further, if the total light amount of the lamps 8 is too small, a darker portion of the document may be read as almost black (black crushing). Therefore, the moving mechanism (the winding motor 14, the winding drum 13, the wire 12, etc.) moves the reading unit 6 so that the convex portion 71 is positioned to read when the light quantity of any one of the light sources 80 is adjusted to be increased. The light emission control unit 10b causes each light source 80 to emit light with the adjusted light amount, the reading unit 6 reads the convex portion 71 of the white reference plate 7, and the density confirmation unit (reading control unit 10) A reference value is determined based on an output value of one light receiving element 90 when the convex portion 71 is read or an average value of output values of a plurality of light receiving elements 90, and the reference value is not within a predetermined allowable range. Sometimes, the light quantity of some or all of the light sources 80 is reduced or increased so as to be within an allowable range. Thereby, as a result of the light amount adjustment, it is possible to prevent the total light amount of each lamp 8 from becoming too much or too little. Here, the “allowable range” can be arbitrarily determined, and an appropriate and suitable reference value range determined in advance by experiments or the like so as to avoid the occurrence of overexposure or blackout in reading the document. It is.

  If the increase is not recognized even when the amount of light is increased, it is considered that the lamp 8 (left lamp 8L, right lamp 8R) has failed. In view of this, the image reading apparatus 100 according to the present embodiment includes a notification unit (operation panel 2) that notifies a message, and the notification unit is a density confirmation unit (reading control) even when the light amount of the light source 80 is adjusted. The unit 10) notifies the abnormality of the lamp 8 when it is not recognized that the amount of light is increasing based on the density values read at the left adjustment position and the right adjustment position. Thereby, it is possible to detect a failure of each lamp 8 (left lamp 8L, right lamp 8R) and to notify the user of the failure.

The mobile mechanism (take-up motor 14, the winding drum 13, the wire 12, etc.), the image sensor 9 of the left adjustment positions from left step 72L is a distance d1 in the reading line comma reading, right step 72R The reading unit 6 is moved to the left adjustment position and the right adjustment position with the same distance (distance d1 = distance d) as the distance d2 from the image sensor 9 to the reading line where the image sensor 9 reads at the right adjustment position. Thereby, the positional relationship between the reading line and the step 72 at the left adjustment position and the positional relationship between the reading line and the step 72 at the right adjustment position can be set to the same conditions. Thereby, the density values of the left adjustment position and the right adjustment position can be compared under the same conditions, and the light amounts of the lamps 8 (the left lamp 8L and the right lamp 8R) can be equalized more accurately.

  The moving mechanism (winding motor 14, winding drum 13, wire 12, etc.) has a distance d1 from the left step 72L to the reading line where the image sensor 9 reads at the left adjustment position in the sub-scanning direction, and The distance d2 from the right step 72R to the reading line on which the image sensor 9 reads at the right adjustment position is based on the distance d3 between the reading line and the lamp 8 (left lamp 8L, right lamp 8R) as viewed from the sub-scanning direction. Also, the reading unit 6 is moved to the left adjustment position and the right adjustment position so that the distance becomes shorter (distance d1 <distance d3, distance d2 <distance d3) (see FIGS. 8 and 9). Thereby, the light from one lamp 8 (the left lamp 8L or the right lamp 8R) can be surely blocked by the step 72. Accordingly, it is possible to reliably recognize the presence or absence of a light amount difference (density value difference) between the lamps 8.

  In addition, the light emission control unit 10b adjusts the light amount of each light source 80 by changing the duty ratio of the voltage applied to the light source 80 or the current to be supplied. Thereby, the light quantity of the light source 80 of the lamp 8 (left lamp 8L, right lamp 8R) can be adjusted.

  In addition, the image reading apparatus 100 according to the present embodiment stores a light amount adjustment table T that defines an adjustment amount of the light amount of the light source 80 according to the difference between the density value at the left adjustment position and the density value at the right adjustment position. 10a is included. Thereby, by referring to the light amount adjustment table T, the adjustment amount for adjusting the light amount of the light source 80 can be determined quickly and easily based on the difference in density value.

  Further, the image forming apparatus (multifunction peripheral 101) of this embodiment includes an image reading apparatus 100. As a result, in the image reading apparatus 100 of the image forming apparatus (multifunction machine 101), the light amounts of the lamps 8 (the left lamp 8L and the right lamp 8R) on both sides of the image sensor 9 are adjusted so that the light amounts are equal. It is possible to obtain image data in which wrinkles and creases are emphasized and image quality in reading is improved. Therefore, an image forming apparatus (multifunction peripheral 101) that performs high-quality printing based on high-quality image data can be provided.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. FIG. 14 is an explanatory diagram for explaining how to determine the density value in the second embodiment.

  This embodiment is different from the first embodiment in that a plurality of left adjustment positions and a plurality of right adjustment positions are set. Further, it differs in that the density value at the left adjustment position and the density value at the right adjustment position are obtained by using the reading results at each position of the plurality of left adjustment positions and the reading results at each position of the plurality of right adjustment positions. . In other respects, it may be the same as that of the first embodiment, and the common parts will be omitted and the illustrations and descriptions will be omitted.

  Specifically, in the present embodiment, a plurality of left adjustment positions are set. At this time, the reading control unit 10 controls the winding motor 14 to move it to each left adjustment position. The reading unit 6 performs reading at a plurality of left adjustment positions. The reading control unit 10 sets the average value of the output values of the respective light receiving elements 90 in the block predetermined so as to straddle the plurality of lines as the density value at the left adjustment position for the plurality of lines obtained by the reading.

  For example, assume that three left adjustment positions are set. And as shown in FIG. 14, the output value of each light receiving element 90 of the image sensor 9 for 3 lines is obtained. Then, in order to determine the density value at the left adjustment position, the reading control unit 10 outputs the output value of each light receiving element 90 in, for example, a 3 × 3 block (shown by hatching in FIG. 14) across adjacent lines. The average value is defined as the concentration value.

  Similarly, in the present embodiment, a plurality of right adjustment positions are also set. At this time, the reading control unit 10 controls the winding motor 14 to move it to each right adjustment position. For example, the number of right adjustment positions is the same as that of the left adjustment positions. Also, the distance d2 from the reading line step 72 (right step 72R) at each right adjustment position may be equal to the distance d1 from the reading line step 72 (left step 73R) at each left adjustment position. Then, the reading unit 6 performs reading at a plurality of right adjustment positions. The reading control unit 10 calculates the average value of the output values (digital) of the respective light receiving elements 90 in the block predetermined so as to straddle the plurality of lines for the plurality of lines obtained by the reading at the right adjustment position. And

  For example, like the left adjustment position, three right adjustment positions are set. And as shown in FIG. 14, the output value of each light receiving element 90 of the image sensor 9 for 3 lines is obtained. Then, in order to determine the density value at the right adjustment position, the reading control unit 10 straddles adjacent lines, as in the case of the left adjustment position, for example, a 3 × 3 block (shown by shading in FIG. 14). ) Is determined as the density value.

  Then, comparing the density value at the left adjustment position with the density value at the right adjustment position, the reading control unit 10 determines the light quantity adjustment amount and corrects the light quantity data so that the difference in density value is eliminated. The light quantity of the light source 80 of the darker lamp 8 is increased. The flow of light amount adjustment itself may be the same as that in the first embodiment described with reference to FIG.

  As described above, in the image reading apparatus 100 according to the present embodiment, the moving mechanism (the winding motor 14, the winding drum 13, the wire 12, etc.) moves the reading unit 6 to a plurality of different left adjustment positions, and a plurality of moving mechanisms. The reading unit 6 is moved to different right adjustment positions, the reading unit 6 performs reading at each of the left adjustment position and the right adjustment position, and the density confirmation unit (reading control unit 10) reads at each left adjustment position. For the plurality of lines, the density value of the left adjustment position is determined based on the average value of the output values of the plurality of light receiving elements 90 included in a block of a predetermined number of light receiving elements 90 in the main scanning direction and the sub-scanning direction, The average value of the output values of a plurality of light receiving elements 90 included in a predetermined number of blocks of the light receiving elements 90 in the main scanning direction and the sub scanning direction with respect to the plurality of lines read at the respective right adjustment positions. Based determines the density value of the right adjustment position, determining the adjustment amount of the light quantity of the light source 80 so that the difference of each density value is eliminated. Thus, by taking the average of the plurality of light receiving elements 90 included in the block, it is possible to recognize the difference in density value (difference in light amount) while reducing individual differences and variations regarding the reading characteristics of each light receiving element 90. it can.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG. FIG. 15 is a schematic view of the reading unit 6 in the third embodiment as viewed from above.

  In the present embodiment, among the four light sources 80, the light source 80 on the near side in the main scanning direction (viewed from the front of the image reading apparatus 100 and the multifunction machine 101) is the light source of the left lamp 8L and the right lamp 8R on the near side. The light amount is adjusted by a combination of 80, and the light source 80 on the back side is different in that the light amount is adjusted by a combination of the light source 80 of the left lamp 8L and the right lamp 8R. The other points may be the same as those of the first and second embodiments, and the common parts will be omitted from the illustration and description as being used.

  In the reading unit 6 of the present embodiment, as shown in FIG. 15, light sources 80 (LEDs) are provided at both ends of the light guide 81 of the left lamp 8L, as in the first and second embodiments, and the right lamp 8R. Light sources 80 (LEDs) are also provided at both ends of the light guide 81.

  At this time, the light emitted from the near side of the light guide 81 may tend to increase the component of the light emitted from the light source 80 on the near side. On the other hand, the light emitted from the back side of the light guide 81 may tend to increase the component of the light emitted from the light source 80 on the back side. Therefore, for the front side, the light amount of the light source 80 is adjusted by combining the light source 80 on the front side of the left lamp 8L and the light source 80 on the front side of the right lamp 8R. The light amount of the light source 80 is adjusted by a combination of the light source 80 on the back side of the left lamp 8L and the light source 80 on the back side of the right lamp 8R.

  Specifically, the light amount adjustment is performed with the combination of the light source 80 of the left lamp 8L on the front side and the light source 80 of the right lamp 8R, and the combination of the light source 80 of the left lamp 8L on the back side and the light source 80 of the right lamp 8R. explain. The flow of light amount adjustment itself may be the same as that in the first embodiment described with reference to FIG.

  First, the reading control unit 10 controls the winding motor 14 to set the reading unit 6 to the left adjustment position. Then, the reading control unit 10 causes the image sensor 9 to perform reading. Here, in order to obtain the density value related to the light source 80 of the left lamp 8L on the near side, the reading control unit 10 outputs the output value of one light receiving element 90 of the image sensor 9 located on the near side from the center of the lamp 8, or The average value of the output values of the plurality of light receiving elements 90 is determined as the density value on the near side of the left adjustment position. Further, in order to obtain a density value related to the light source 80 of the left lamp 8L on the back side, the reading control unit 10 outputs the output value of one light receiving element 90 of the image sensor 9 located on the back side from the center of the lamp 8, or The average value of the output values of the plurality of light receiving elements 90 is determined as the density value at the left adjustment position.

  Next, the reading control unit 10 controls the winding motor 14 to set the reading unit 6 to the right adjustment position. Then, the reading control unit 10 causes the image sensor 9 to perform reading. Here, in order to obtain a density value related to the light source 80 of the right lamp 8R on the near side, the reading control unit 10 outputs the output value of one light receiving element 90 of the image sensor 9 located on the near side from the center of the lamp 8, or The average value of the output values of the plurality of light receiving elements 90 is determined as the density value on the near side of the right adjustment position. Further, in order to obtain a density value related to the light source 80 of the right lamp 8R on the back side, the reading control unit 10 outputs the output value of one light receiving element 90 of the image sensor 9 located on the back side from the center of the lamp 8, or The average value of the output values of the plurality of light receiving elements 90 is determined as the density value at the right adjustment position.

  Thus, in the present embodiment, unlike the first and second embodiments, the reading control unit 10 obtains four types of density values. Note that the light receiving element 90 that is a target for obtaining the density value is the light receiving element 90 at the same position in the left adjustment position and the right adjustment position.

  The reading control unit 10 compares the density value at the front left adjustment position with the density value at the right adjustment position. Then, the reading control unit 10 uses the density value difference and the light amount adjustment table T1 stored in the storage unit 10a as in the first embodiment, and the darkness (darker) density value of the lamp 8 is determined. The amount of adjustment is determined so that the amount of light from the light source 80 on the near side increases. Then, the reading control unit 10 corrects the light amount data of the light source 80 on the near side of the darker lamp 8. As described above, with respect to the near-side light source 80, the combination of the near-side light source 80 eliminates the density value difference.

  The reading control unit 10 compares the density value at the left adjustment position on the back side with the density value at the right adjustment position on the back side as well as the front side. Then, the reading control unit 10 uses the density value difference and the light amount adjustment table T1 stored in the storage unit 10a as in the first embodiment, and the darkness (darker) density value of the lamp 8 is determined. The adjustment amount is determined so that the light amount of the light source 80 on the back side increases. Then, the reading control unit 10 corrects the light amount data of the light source 80 on the back side of the darker lamp 8. As described above, with respect to the light source 80 on the back side, the difference in density value is eliminated by combining the light source 80 on the back side.

In the lamp 8 (the left lamp 8L and the right lamp 8R) provided with the light sources 80 at both ends of the light guide 81 that emits light in the main scanning direction, the light source 80 provided on the front side as viewed from the main scanning direction. More light is emitted (the influence of the light source 80 provided on the front side is strong), and more light from the light source 80 provided on the back side is emitted on the back side as viewed from the main scanning direction ( The influence of the light source 80 provided on the back side is strong). Therefore, in the image reading apparatus 100 of the present embodiment, each lamp 8 (left lamp 8L, right lamp 8R) includes a rod-shaped light guide 81 and two light sources 80 at both ends of the light guide 81, so that the density check is performed. The unit (reading control unit 10) of the two light sources 80 on the near side when viewed from the main scanning direction is configured by one light receiving element 90 positioned on the near side of the center of the lamp 8 when read at the left adjustment position. Based on the output value or the average value of the output values of the plurality of light receiving elements 90, the density value at the left adjustment position is determined, and one light reception located on the near side of the center of the lamp 8 when read at the right adjustment position. The density value at the right adjustment position is determined based on the output value of the element 90 or the average value of the output values of the plurality of light receiving elements 90, and the light amount adjustment amount of the light source 80 on the near side is eliminated so that there is no difference between the density values. To the light source 80 on the back side when viewed from the main scanning direction. In this case, based on the output value of one light receiving element 90 located behind the center of the lamp 8 when read at the left adjustment position or the average value of the output values of a plurality of light receiving elements 90, Is determined based on the average value of the output values of one light receiving element 90 or a plurality of light receiving elements 90 positioned on the near side of the center of the lamp 8 when read at the right adjustment position. The density value at the adjustment position is determined, and the adjustment amount of the light amount of the back light source 80 is determined so that there is no difference between the density values. Thereby, the light quantity of each light source 80 provided at both ends of the lamp 8 (left lamp 8L, right lamp 8R) is changed to the lamp 8 (left lamp 8L, right lamp 8R) by the combination of the light sources 80 on the front side and the back side. ) Can be adjusted appropriately.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG. FIG. 16 is a schematic view of the reading unit 6 in the fourth embodiment as viewed from above.

  In the present embodiment, as shown in FIG. 4, one light source 80 is provided for the light guide 81. In other words, each of the left lamp 8L and the right lamp 8R of the reading unit 6 of the present embodiment includes one light source 80. Therefore, the reading unit 6 of the present embodiment has a total of two light sources 80. The reading unit 6 of this embodiment is different from the first to third embodiments in the number of light sources 80. In the present embodiment, since the number of light sources 80 is reduced, the amount of light per light source 801 is made larger than in the first to third embodiments. Other points may be the same as those in the first to third embodiments, and common parts are not shown or described as being incorporated.

  Specifically, in the present embodiment, the reading control unit 10 controls the winding motor 14 to move the reading unit 6 to the left adjustment position. The reading unit 6 performs reading at the left adjustment position. Further, the reading control unit 10 controls the winding motor 14 to move the reading unit 6 to the right adjustment position. The reading unit 6 performs reading at the right adjustment position. A plurality of adjustment positions may be provided as in the second embodiment.

  For example, in the present embodiment, the reading control unit 10 determines the density value based on the output value of the light receiving element 90 at the center portion of the lamp 8 in reading the left adjustment position. The reading control unit 10 may determine the output value of one light receiving element 90 at the center portion of the lamp 8 as the density value at the left adjustment position, or average the output values of the plurality of light receiving elements 90 at the center portion of the lamp 8. The value may be determined as the density value at the left adjustment position.

  In this embodiment, the reading control unit 10 determines the density value based on the output value of the light receiving element 90 at the center portion of the lamp 8 in the reading of the right adjustment position, similarly to the left adjustment position. The reading control unit 10 may determine the output value of one light receiving element 90 that is the same as that at the left adjustment position as the density value at the right adjustment position. The average value of the output values of the light receiving element 90 at the same position as that at the adjustment position may be determined as the density value at the right adjustment position.

  Then, the reading control unit 10 compares the density value at the determined left adjustment position with the density value at the right adjustment position. Then, the reading control unit 10 uses the density value difference and the table stored in the storage unit 10a as in the first embodiment, and uses the table stored in the storage unit 10a on the front side of the lamp 8 having the darker (darker) density value. The light amount data of the light source 80 on the near side of the darker lamp 8 is corrected so that the light amount of the light source 80 increases. In this way, the light amount of the light source 80 of the left lamp 8L and the right lamp 8R is adjusted to eliminate the density value difference.

In a lamp 8 (left lamp 8L, right lamp 8R) provided with a light source 80 at one end of a light guide 81 that emits light in the main scanning direction, main scanning of the lamp 8 (left lamp 8L, right lamp 8R) is performed. One guideline is whether the amount of light at the center of the direction is appropriate. In the image reading apparatus 100 (multifunction machine 101) of the present embodiment, each lamp 8 (left lamp 8L, right lamp 8R) has a rod-shaped light guide 81 and one light source at the end of the light guide 81. 80, and the density confirmation unit (reading control unit 10) outputs an output value of one light receiving element 90 positioned at the central portion of the lamp 8 when read at the left adjustment position, or output values of a plurality of light receiving elements 90. The density value at the left adjustment position is determined based on the average value of the two, and the output value of one light receiving element 90 or the output values of the plurality of light receiving elements 90 positioned at the center portion of the lamp 8 when read at the right adjustment position. Based on the average value, the density value at the right adjustment position is determined, and the light amount adjustment amount of the light source 80 is determined so that there is no difference between the density values. Thereby, the light quantity of each light source 80 provided in one edge part of the lamp | ramp 8 can be adjusted appropriately.

(Fifth embodiment)
Next, a fourth embodiment will be described with reference to FIG. FIG. 17 is an explanatory diagram illustrating an example of the light amount adjustment table T2 according to the fifth embodiment.

  In the first to fourth embodiments, the example in which the light emission control unit 10b increases or decreases the light amount of one light source 80 by changing the light amount of the light source 80 (LED) by changing the duty ratio of the PWM signal has been described. In the present embodiment, instead of the duty ratio, the light emission control unit 10b corrects the light amount of the light source 80 by changing the magnitude of the current. Therefore, the light emission control unit 10b according to the present embodiment provides a circuit that can individually supply current to each light source 80 and change the magnitude of the current (voltage) supplied to each light source 80 for each light source 80. Including. Accordingly, the storage unit 10a stores a current value supplied (flowed) for each light amount as light amount data indicating the light amount. Then, the reading control unit 10 causes the light emission control unit 10b to supply current to each light source 80 based on the light amount data of each light source 80 stored in the storage unit 10a.

  Here, when adjusting the light amount of each lamp 8, the reading control unit 10 determines the difference between the density value determined based on reading at the left adjustment position and the density value based on reading at the right adjustment position (left lamp 8L). The difference between the light amount of the light source 80 and the light amount of the light source 80 of the right lamp 8R), and if there is a difference in density value, the light amount data of the light source 80 of the darker lamp 8 is corrected. This is the same as the fourth embodiment.

Specifically, the reading control unit 10 corrects the light amount data of the darker lamp 8 based on the difference in density value between the left adjustment position and the right adjustment position, and stores the corrected data in the storage unit 10a. The reading control unit 10 corrects the light amount of the light source 80 of the darker lamp 8 to increase. The reading control unit 10 determines how much the current of the light source 80 that increases the amount of light is increased based on the difference in density value (determines an adjustment amount ).

  For example, as shown in FIG. 17, a light amount adjustment table T2 in which the amount of current to be increased with respect to the difference in density value is stored in the storage unit 10a. Then, the reading control unit 10 refers to the light amount adjustment table T2, and determines the magnitude of the current added to the light source 80 to increase the light amount from the current state according to the difference in density value between the left adjustment position and the right adjustment position. Determine (determine the amount of adjustment). Then, the reading control unit 10 corrects by adding the magnitude of the current determined to be added to the current current magnitude of the light source 80 to increase the light quantity, and stores the corrected light quantity data in the storage unit 10a. Let As in the first to fourth embodiments, when the difference between the density values of the left adjustment position and the right adjustment position falls within a predetermined tolerance, the reading control unit 10 is data indicating the light amount of the light source 80. It is not necessary to perform the correction.

  In this way, the light emission control unit 10b of the present embodiment adjusts the light amount of each light source 80 by changing the voltage applied to the light source 80 or the magnitude of the supplied current. Thereby, the light quantity of the light source 80 of the lamp 8 (left lamp 8L, right lamp 8R) can be adjusted.

  The present invention can be used for an image reading apparatus provided with lamps on both sides of an image sensor, and an image forming apparatus including the image reading apparatus.

DESCRIPTION OF SYMBOLS 100 Image reading apparatus 101 Multifunction machine (image forming apparatus)
1 Image Reading Unit 10 Reading Control Unit (Density Confirmation Unit)
10a Storage unit 10b Light emission control unit 12 Wire (movement mechanism) 13 Winding drum (movement mechanism)
14 Winding motor (movement mechanism) 2 Operation panel (notification part)
6 Reading unit 7 White reference plate 71 Convex part 72 Step 72L Left step 72R Right step 8 Lamp 8L Left lamp (Lamp)
8R Right lamp (lamp) 80 Light source 81 Light guide 9 Image sensor 90 Light receiving element S1 Abnormality notification screen T1 Light amount adjustment table T2 Light amount adjustment table

Claims (11)

An image sensor in a main scanning direction a plurality of light receiving elements are arranged, the main scanning direction and the longitudinal direction against the image sensor is provided on the left and right sides of the sub-scanning direction, and two lamps each having a light source A reading unit that turns on each of the light sources when reading a document and reads by the image sensor;
A moving mechanism for moving the reading unit in the sub-scanning direction;
A light emission control unit for controlling light emission of the light source of each of the lamps;
Together provided on a moving path of the reading unit, provided above the reading portion, the central portion of the sub-scanning direction on the surface of the lower, as well as have a downward convex portion, the sub to the protrusions A white reference plate provided with flat surface portions located above the lower surface of the convex portion on both the left and right sides in the scanning direction ;
A density confirmation unit that determines a density value that is a value indicating density based on an output value of each light receiving element of the image sensor;
Of the flat surface portion on the left side in the sub-scanning direction, the irradiation from the lamp on the left side is a position that is a predetermined distance away from the step between the flat surface portion on the left side in the sub-scanning direction and the convex portion. The position where light reaches the flat surface portion on the left side in the sub-scanning direction and the light from the lamp on the right side in the sub-scanning direction is blocked by a step and does not reach the flat surface portion on the left side in the sub-scanning direction is defined as the left adjustment position. Of the flat surface portion on the right side in the direction, a position separated from the step between the flat surface portion on the right side in the sub-scanning direction and the convex portion by a predetermined distance to the right side in the sub-scanning direction, and the irradiation light from the right lamp is A right adjustment position, a position that reaches the flat surface portion on the right side in the sub-scanning direction, the irradiation light from the left lamp is blocked by a step and does not reach the flat surface portion on the right side in the sub-scanning direction,
The moving mechanism, together with the image sensor moves the reading unit in a position for reading the left adjustment position, the reading portion and the image sensor moves the reading unit in a position for reading the right adjustment position, the left Read at the adjustment position and the right adjustment position,
The density check unit adjusts the light amount of the light source of each lamp so that there is no difference between the density value obtained by reading at the left adjustment position and the density value obtained by reading at the right adjustment position. Set the adjustment amount individually ,
The light emission control unit individually adjusts the light amount of the light source of each lamp based on the adjustment amount.   When the density confirmation unit recognizes that the reading at the left adjustment position is darker, the adjustment amount is determined so as to increase the light amount of the light source of the left lamp, and the density confirmation unit determines the right adjustment position. The image reading apparatus according to claim 1, wherein the adjustment amount is determined so as to increase a light amount of the light source of the lamp on the right side when it is recognized that the reading at the dark side is darker.   The density confirmation unit determines a density value of the left adjustment position based on an output value of one light receiving element or an average value of output values of the plurality of light receiving elements when read at the left adjustment position, and The density value of the right adjustment position is determined based on an output value of one light receiving element or an average value of output values of a plurality of light receiving elements when read at an adjustment position. The image reading apparatus described. The moving mechanism moves the reading unit so as to be a position to read the convex portion when adjustment to increase the light amount of any one of the light sources is performed,
The light emission control unit causes each light source to emit light with the adjusted light amount,
The reading unit reads the convex portion of the white reference plate,
The density confirmation unit determines a reference value based on an output value of one of the light receiving elements when the convex portion is read or an average value of output values of the plurality of light receiving elements, and the reference value is determined in advance. 4. The image reading according to claim 1, wherein when the light source does not fall within the allowable range, the light amount of a part or all of the light sources is reduced or increased so as to fall within the allowable range. apparatus. The moving mechanism includes a distance in the reading line comma to the image sensor in the left adjustment position from the left side of the step is to read, said image sensor in the right adjustment position from the right side of the step to read The distance to the reading line is set to the same distance, and the reading unit is moved to the left adjustment position and the right adjustment position. Image reading device.   In the sub-scanning direction, the moving mechanism includes a distance from the left step to the reading line at which the image sensor reads at the left adjustment position, and the image sensor at the right adjustment position from the right step. The reading unit is moved to the left adjustment position and the right adjustment position so that the distance to the reading line for reading is shorter than the distance between the reading line and the lamp as viewed in the sub-scanning direction. The image reading apparatus according to claim 1, wherein: The moving mechanism moves the reading unit to a plurality of different left adjustment positions, and moves the reading unit to a plurality of different right adjustment positions,
The reading unit performs reading at each of the left adjustment position and the right adjustment position,
The density confirmation unit is configured to average an output value of a plurality of light receiving elements included in a predetermined number of light receiving element blocks in a main scanning direction and a sub scanning direction for a plurality of lines read at each of the left adjustment positions. A density value at the left adjustment position is determined based on the value, and a plurality of lines read at each of the right adjustment positions are included in a plurality of blocks of light receiving elements that are predetermined in the main scanning direction and the sub-scanning direction. The density value of the right adjustment position is determined based on the average value of the output values of the light receiving elements, and the adjustment amount of the light amount of the light source is determined so that there is no difference between the density values. The image reading apparatus according to claim 1. Each lamp includes a rod-shaped light guide and two light sources at both ends of the light guide,
For the two light sources on the near side as viewed from the main scanning direction, the density confirmation unit outputs an output value of one light receiving element located on the near side of the center of the lamp when read at the left adjustment position, Alternatively, the one light receiving element positioned on the front side of the center of the lamp when the density value at the left adjustment position is determined based on an average value of output values of the plurality of light receiving elements and read at the right adjustment position. Or the average value of the output values of the plurality of light receiving elements to determine the density value at the right adjustment position, and the light amount adjustment amount of the light source on the near side so that there is no difference between the density values And
For the light source on the back side when viewed from the main scanning direction, the output value of one light receiving element located on the back side from the center of the lamp when read at the left adjustment position, or a plurality of light receiving elements The density value at the left adjustment position is determined based on the average value of the output values, and the output value of one light receiving element located behind the center of the lamp when read at the right adjustment position, or a plurality of values The density value at a right adjustment position is determined based on an average value of output values of the light receiving elements, and an adjustment amount of the light amount of the light source on the back side is determined so that a difference between the density values is eliminated. Item 7. The image reading apparatus according to any one of Items 1 to 6. Each of the lamps includes a rod-shaped light guide and one light source at an end of the light guide,
The density confirmation unit is configured to adjust the left adjustment based on an output value of one light receiving element located at a central portion of the lamp when read at the left adjustment position or an average value of output values of a plurality of light receiving elements. The density value at a position is determined, and based on the output value of one light receiving element located at the center of the lamp when read at the right adjustment position, or the average value of the output values of a plurality of light receiving elements The image according to any one of claims 1 to 6, wherein the density value at the right adjustment position is determined, and an adjustment amount of the light amount of the light source is determined so that a difference between the density values is eliminated. Reader.   The storage unit stores a light amount adjustment table that defines an adjustment amount of the light amount of the light source according to a difference between the density value at the left adjustment position and the density value at the right adjustment position. The image reading apparatus according to any one of 1 to 9.   An image forming apparatus comprising the image reading apparatus according to claim 1.

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