JP6500855B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus which reads an original and generates image data, and an image forming apparatus provided with the image reading apparatus.

  The image reading apparatus reads an original based on the reflected light of the original. The image reading apparatus is provided with a light source for irradiating the document along the main scanning direction. In recent years, many light sources use LEDs. For example, in some image reading apparatuses, LEDs are arranged in a row to irradiate light to a document. Some image reading apparatuses use a linear light guide provided with an LED at the end to irradiate light to a document.

  Specifically, in Patent Document 1, light guides 402a and 402b for emitting light flux on the document surface are provided between the LED substrates 401a and 401b and between the LED substrates 401c and 401d, and both ends in the main scanning direction An image reader with LEDs on each side is described. (Patent Document 1: Paragraphs [0040], [0041], FIG. 4 and the like).

JP, 2011-193514, A

  In the image reading apparatus, a plurality of light sources such as LEDs may be used in order to secure a sufficient amount of light. For example, in Patent Document 1, two light guides are provided so as to sandwich a reading line in the sub scanning direction, and LEDs are provided at both ends of each light guide. In an image reading apparatus including such a plurality of light guides and a plurality of light sources, there is a problem that extreme image quality deterioration may occur depending on the connection method of each light source when a failure of the light source occurs.

  In the image reading apparatus described in Patent Document 1, a lighting control circuit (a constant current circuit and a switching circuit) is provided for each LED (Patent Document 1: see FIG. 14). Therefore, the image reading apparatus described in Patent Document 1 has a large number of lighting control circuits, which causes a problem in manufacturing cost. In addition, since the number of lighting control circuits is large, there is a problem that control and wiring become complicated.

  SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, the present invention suppresses the manufacturing cost of the image reading apparatus and simplifies the lighting control, and prevents the image quality from being extremely degraded even if a failure occurs in the light source.

  In order to achieve the above object, in the image reading apparatus according to claim 1, the image reading apparatus comprises an image sensor, a first light guide, a second light guide, a first light source, a second light source, a third light source, A fourth light source, a first lighting circuit, and a second lighting circuit are included. The image sensor has a plurality of light receiving elements arranged in the main scanning direction. The first light guide is provided along the main scanning direction, and is provided on one side in the sub scanning direction with respect to the reading line of the image sensor. The second light guide is provided along the main scanning direction, and is provided on the other side in the sub scanning direction with respect to the reading line of the image sensor. The first light source is provided to face one end of the first light guide. The second light source is connected in series to the first light source and is provided to face the other end of the second light guide. The third light source is provided to face one end of the second light guide. The fourth light source is connected in series to the third light source and is provided to face the other end of the first light guide. The first lighting circuit turns on / off the first light source and the second light source. The second lighting circuit turns on / off the third light source and the fourth light source.

  According to the present invention, it is possible to provide an image reading apparatus with reduced manufacturing cost, simplified lighting control, and extremely low image quality even if a failure occurs in the light source.

FIG. 1 is a diagram illustrating an example of a multifunction peripheral according to an embodiment. FIG. 1 is a diagram illustrating an example of an image reading apparatus according to an embodiment. FIG. 1 is a diagram illustrating an example of an image reading apparatus according to an embodiment. It is a sectional view of a reading unit concerning an embodiment. It is a figure which shows an example of arrangement | positioning of LED as a light source which concerns on embodiment, and a light guide. It is a figure which shows an example of the output of an image sensor in the case of one light source to light. It is a figure which shows an example of the output of an image sensor when making all the light sources light. It is a figure which shows an example of the output of an image sensor when all the light sources are light-extinguished. It is a figure which shows the connection with each lighting circuit and each light source in the image reader which concerns on embodiment. FIG. 10 is an explanatory diagram of Comparative Example 1; FIG. 10 is an explanatory diagram of Comparative Example 2; FIG. 18 is an explanatory diagram of Comparative Example 3; FIG. 18 is an explanatory view of a comparative example 4; It is a flowchart which shows an example of a flow of failure determination of the light source in the image reading apparatus which concerns on embodiment. It is a flowchart which shows an example of a flow of failure determination of the light source in the image reading apparatus which concerns on embodiment. It is a figure which shows an example of the determination result alerting | reporting screen which concerns on embodiment.

  The image reading apparatus 1 and the image forming apparatus provided with the image reading apparatus 1 will be described below with reference to FIGS. The MFP 100 will be described as an example of the image forming apparatus. Each element such as the configuration and arrangement described in the description of the present embodiment does not limit the scope of the invention and is merely an example.

(MFP 100)
The MFP 100 according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a multifunction peripheral 100 according to the embodiment.

  As shown in FIG. 1, the multifunction device 100 includes an image reading device 1, a main control unit 2, a storage unit 20, a printing unit 21, an operation panel 22, and a communication unit 23. The image reading apparatus 1 includes a document conveyance unit 3 and an image reading unit 4. The operation panel 22 also functions as a portion that performs settings related to the image reading device 1 and a portion that performs display related to the image reading device 1.

  The main control unit 2 is responsible for overall control of the multifunction device 100. The main control unit 2 includes a CPU 2a. In addition, the multi-function device 100 is provided with a storage unit 20 including a non-volatile storage device such as a ROM, an HDD, and a flash ROM and a volatile storage device such as a RAM. The main control unit 2 controls each unit using a program and data stored in the storage unit 20. The main control unit 2 controls scanning, printing, transmission, and storage of image data performed in a job such as copying and transmission. Further, the main control unit 2 is provided with an image processing unit 2 b that performs image processing according to a job on the image data generated by the image reading unit 4.

  The operation panel 22 includes a display panel 24, a touch panel 25, and hard keys 26. The main control unit 2 recognizes an operated one of operation images such as keys and buttons displayed on the display panel 24 based on the output of the touch panel 25. The hard key 26 includes a start key for instructing start of job execution, and a numeric keypad for inputting numbers. The main control unit 2 causes the display panel 24 to display the state of the operation panel 22, various messages, and a setting screen. The operation panel 22 receives setting operations on the touch panel 25 and the hard keys 26 in connection with jobs such as scanning and copying. The main control unit 2 communicates with the operation panel 22 to recognize setting contents.

  The printing unit 21 includes a sheet feeding unit 27, a conveyance unit 28, an image forming unit 29, and a fixing unit 210. The paper feed unit 27 feeds paper. The transport unit 28 transports the sheet and discharges the printed sheet to the outside of the machine. The image forming unit 29 forms a toner image on the basis of the image data, and transfers the toner image to a sheet to be conveyed. The fixing unit 210 fixes the transferred toner image on a sheet. The main control unit 2 controls the operation of the printing unit 21.

  The multifunction device 100 also includes a communication unit 23. The communication unit 23 is communicably connected to the FAX apparatus 300 and a computer 200 such as a PC or a server. The main control unit 2 causes the communication unit 23 to transmit image data based on the reading result of the document to the computer 200 or the fax apparatus 300 set as the destination (scan transmission, FAX transmission). Further, the main control unit 2 causes the printing unit 21 to print the data transmitted from the computer 200 or the FAX apparatus 300 and received by the communication unit 23 (print job, FAX reception printing).

(Image reader 4 and document feeder 3)
Next, the image reading apparatus 1 according to the embodiment will be described with reference to FIGS. 2 and 3 are diagrams showing an example of the image reading apparatus 1 according to the embodiment.

  As shown in FIG. 2, the document conveyance unit 3 is provided above the image reading unit 4. The document transport unit 3 opens and closes vertically with respect to the image reading unit 4 and functions as a cover for pressing the document from above. Further, the document conveyance unit 3 conveys the set document toward the conveyance reading contact glass 41 (reading position). The document conveyance unit 3 further includes a document tray 31, a supply roller 32, a document conveyance path 33, a plurality of conveyance roller pairs 34, a discharge roller pair 35, and a discharge tray 36 in this order from the upstream side of the document conveyance direction.

  A document set sensor 37 for detecting whether or not there is a sheet in the document tray 31 is provided in the document transport unit 3 (see FIG. 2). When an instruction to execute a job for reading an original such as copying or transmission is issued to the operation panel 22 (when the start key is operated), the main control unit 2 confirms the output of the original set sensor 37, and the original tray It is detected whether there is a document set to 31 or not. When a document is present on the document tray 31, the main control unit 2 drives a document conveyance motor (not shown) to rotate the supply roller 32 and the conveyance roller pair 34 to convey the document toward the reading position. The document passes above the transport reading contact glass 41 provided on the upper surface of the image reading unit 4. At the time of this passage, the reading unit 5 of the image reading unit 4 reads the document (conveyance reading).

  As shown in FIG. 2, the conveyance reading contact glass 41 is provided on the top left side of the image reading unit 4. The placement reading contact glass 42 is disposed on the upper surface of the image reading unit 4 and on the right side of the conveyance reading contact glass 41. A document such as a book is set on the placement reading contact glass 42. In other words, the placement reading contact glass 42 functions as a table on which one page of document is set. When a document is not set in the document conveyance unit 3, the image reading unit 4 emits light to the document set in the contact glass for placement reading 42, reads the surface of the document based on reflection, and generates image data Yes (table read).

  As shown in FIG. 3, the image reading unit 4 is provided with a reading control unit 40 (corresponding to a control unit) that controls the operation of the image reading unit 4. The reading control unit 40 is a substrate including a scanner CPU 40a, a scanner memory 40b, and other circuits. The reading control unit 40 receives an instruction and a signal from the main control unit 2 and reads an original.

  As shown in FIG. 2, the image reading unit 4 includes a reading unit 5, a wire 43, and a winding drum 44 in a housing 51. The reading unit 5 is connected to the winding drum 44 by a wire 43. The winding drum 44 is rotated by a winding motor 45 (see FIG. 3) rotating in forward and reverse directions. At the time of table reading, the reading control unit 40 rotates the winding drum 44 to move the reading unit 5 in the horizontal direction. At the time of conveyance reading, the reading control unit 40 fixes the reading unit 5 below the conveyance reading contact glass 41.

  As shown in FIG. 3, a reading unit 5 and an image data generation unit 46 are provided in the image reading unit 4. The reading unit 5 is a CIS unit. The reading unit 5 emits light to the document, and outputs an analog electric signal according to the amount of reflected light for each pixel in the main scanning direction (light receiving element of the image sensor 6). Details of the reading unit 5 will be described later.

  The image data generation unit 46 includes an A / D conversion unit 47, a correction unit 48, and an image memory 49. The A / D conversion unit 47 processes the analog signal of each light receiving element of the image sensor 6 and converts the analog signal of each light receiving element into a digital value. The A / D conversion unit 47 converts analog signals from the respective light receiving elements into 8-bit or 10-bit digital values. The correction unit 48 performs processing for correcting distortion in density of an image caused by reading such as shading correction. The image data of each line generated by the image data generation unit 46 is accumulated in the image memory 49 and transmitted to the storage unit 20. When executing a job such as copying or transmission, image data stored in the storage unit 20 is read out. The image processing unit 2 b performs image processing according to the setting on the operation panel 22 on the read image data. Data after image processing is used for jobs such as copy jobs and transmission jobs.

(Reading unit 5)
Next, the reading unit 5 of the image reading apparatus 1 according to the embodiment will be described with reference to FIGS. 3 to 5. FIG. 4 is a cross-sectional view of the reading unit 5 according to the embodiment. Drawing 5 is a figure showing an example of arrangement of LED as a light source concerning an embodiment, and a light guide.

  As shown in FIG. 4, the reading unit 5 includes a housing 51 having a substantially U-shaped cross section. The vertical direction of the paper surface of FIG. The longitudinal direction of the housing 51 is the main scanning direction. A plate-like glass 52 is attached to the top surface of the housing 51 so as to close the opening on the top surface.

  An image sensor 6, a first light guide 71, a second light guide 72, a plurality of light sources (a first light source 81, a second light source 82, a third light source 83, a fourth light source) 84), a rod lens array 53 is provided.

  In addition, a first lighting circuit 91 that controls lighting of the first light source 81 and the second light source 82, and a second lighting circuit 92 that controls lighting of the third light source 83 and the fourth light source 84 are provided. As shown in FIG. 3, the first lighting circuit 91 and the second lighting circuit 92 may be provided in the reading unit 5. The first lighting circuit 91 and the second lighting circuit 92 may be provided outside the reading unit 5.

  At the time of document reading, the reading control unit 40 instructs the first lighting circuit 91 and the second lighting circuit 92 to turn on the light source. When the lighting instruction is received, the first lighting circuit 91 and the second lighting circuit 92 supply a current to the connected light source to light the light source. When the document reading is completed, the reading control unit 40 instructs the first lighting circuit 91 and the second lighting circuit 92 to turn off the light source. When receiving the turn-off instruction, the first lighting circuit 91 and the second lighting circuit 92 stop the supply of current to the connected light source, and turn off the light source. The details of the connection of each lighting circuit and each light source will be described later.

  An image sensor 6 is provided on the inner lower surface of the housing 51 along the direction perpendicular to the sheet of FIG. 4 (main scanning direction). The image sensor 6 is a line sensor in which a plurality of light receiving elements (photoelectric conversion elements) are arranged along the main scanning direction. The image sensor 6 is longer than the short side of the A3 size sheet so that the A3 size sheet can be read. The image sensor 6 supports color reading and includes a plurality of line sensors. A clock signal having a predetermined frequency is input to the image sensor 6, and the output of each light receiving element is sequentially input to the image data generation unit 46 (A / D conversion unit 47) in accordance with the clock signal.

  Above the image sensor 6, a rod lens array 53 is provided. The rod lens array 53 is formed by arranging a plurality of rod lenses in the main scanning direction. The reflected light of the reading object (original) is guided to the image sensor 6.

  Linear (rod-like) light guides are provided on the left and right sides of the rod lens array 53 (image sensor 6, reading line). The light guide is parallel to the main scanning direction. The first light guide 71 is a light guide provided on one side in the sub scanning direction with respect to the image sensor 6. The second light guide 72 is a light guide provided on the other side in the sub scanning direction with respect to the image sensor 6 (reading line). In other words, the first light guide 71 is a light guide on one side (left side) when the image reading device 1 (the MFP 100) is viewed from the front. The second light guide 72 is a light guide on the other side (right side) when the image reading device 1 (the MFP 100) is viewed from the front.

  Each light guide transmits the light incident from the end (end face) along the main scanning direction. Reflectors (reflectors) are provided at regular intervals in the main scanning direction in each light guide. Each reflector reflects part of the light incident from the end. The light reflected by the reflection part is emitted from the light exit surface of the light guide. As a result, the light guide emits light in a strip shape and illuminates the document with uniform light along the main scanning direction. And a light source is provided in the both ends of each light guide. In other words, two light sources are provided at each end of each light guide in the reading unit 5 in the longitudinal direction (a total of four of the first light source 81, the second light source 82, the third light source 83, and the fourth light source 84). ). Each light source is an LED of the same specification.

  As shown in FIG. 5, a light source provided facing one end of the first light guide 71 is referred to as a first light source 81. A light source provided facing the other end of the second light guide 72 is referred to as a second light source 82. A light source provided facing one end of the second light guide 72 is referred to as a third light source 83. A light source provided facing the other end of the first light guide 71 is referred to as a fourth light source 84. Here, one end means the end (front end) of the light guide on the front side (front side) of the image reading apparatus 1 (the MFP 100 in the main scanning direction). The other end means the end (rear end) of the light guide on the other end side (tail side) of the image reading apparatus 1 (the MFP 100 in the main scanning direction).

  Light emitted from the first light source 81 and the fourth light source 84 is incident on the first light guide 71. The first light guide 71 guides the light emitted from the first light source 81 in the back direction of the main scanning direction. In addition, the first light guide 71 guides the light emitted by the fourth light source 84 in the forward direction of the main scanning direction. The light emitted from the second light source 82 and the third light source 83 is incident on the second light guide 72. The second light guide 72 guides the light emitted by the second light source 82 forward in the main scanning direction. In addition, the second light guide 72 guides the light emitted by the third light source 83 in the backward direction of the main scanning direction. When the four light sources are turned on, each light guide emits light upward of the rod lens array 53 (glass 52) so that the light amount level is substantially uniform at each position in the main scanning direction. Each rod lens included in the rod lens array 53 guides the light reflected by the object to be read to the image sensor 6 while collecting the light. An example of the direction of the light of the reflected light is indicated by a two-dot chain line with an arrow.

(Output of image sensor 6 when light source is on)
Next, an example of the output of the image sensor 6 when the light source is lit will be described using FIGS. 6 to 8. FIG. 6 is a diagram showing an example of the output of the image sensor 6 when only one light source is turned on. FIG. 7 is a diagram showing an example of the output of the image sensor 6 when all four light sources are turned on. FIG. 8 is a diagram showing an example of the output of the image sensor 6 when all the light sources are turned off.

  The vertical axes of FIGS. 6, 7 and 8 correspond to the output of the image sensor 6. The larger the output of the image sensor 6, the larger the amount of light received. The horizontal axis corresponds to the position of the pixel in the main scanning direction.

  In FIG. 6, the solid line indicates the output (analog output voltage) of the image sensor 6 when one of the first light source 81 and the third light source 83 arranged on one end side (front side) in the main scanning direction is lit. An example is shown. In FIG. 6, a broken line indicates an output (analog output) of the image sensor 6 when any one of the second light source 82 and the fourth light source 84 disposed on the other end side (rear side) in the main scanning direction is lit. Voltage)). As shown in FIG. 6, when only one light source is turned on, the analog output voltage increases as the pixel is closer to the light source, and as the distance from the light source increases, the analog output voltage gradually decreases.

  FIG. 7 shows an example of the output of the image sensor 6 when a single-color document such as white is read with all light sources turned on, as in the case of reading a document. When all the light sources are turned on, the output of the image sensor 6 becomes equal at each pixel. FIG. 8 shows an example of the output of the image sensor 6 when all the light sources are turned off. When all the light sources are turned off, the output value of each pixel of the image sensor 6 becomes the lowest value.

(Connection of each light source and lighting circuit)
Next, the connection between each lighting circuit and each light source in the image reading device 1 according to the embodiment will be described with reference to FIG. FIG. 9 is a diagram showing the connection between each lighting circuit and each light source in the image reading device 1 according to the embodiment.

  As shown in FIG. 9, the first light source 81 and the second light source 82 are connected in series. At the time of reading, the first lighting circuit 91 supplies a current to the series circuit of the first light source 81 and the second light source 82. The first lighting circuit 91 turns on and off the first light source 81 and the second light source 82. Thereby, light is emitted from the first light guide 71.

  The third light source 83 and the fourth light source 84 are connected in series. At the time of reading, the second lighting circuit 92 supplies a current to the series circuit of the third light source 83 and the fourth light source 84. In other words, the second lighting circuit 92 turns on and off the third light source 83 and the fourth light source 84. Thereby, light is emitted from the second light guide 72.

  As shown in FIG. 9, two light sources at diagonal positions are combined with the image sensor 6 (reading line, rod lens array 53). In order to enable on / off control in combination units and to accurately identify which light source has failed, two circuits (a first lighting circuit 91 and a second lighting circuit 92) for controlling on / off are provided (details will be described) Later).

(Compare with other connection methods)
Next, comparison with other light source connection methods will be described using FIGS. 10 to 13. FIG. 10 is an explanatory diagram of Comparative Example 1. FIG. 11 is an explanatory diagram of comparative example 2; FIG. 12 is an explanatory diagram of comparative example 3; FIG. 13 is an explanatory view of a comparative example 4;

  An example in which the number of light guides is two and light sources are provided at both ends of the light guides is given as a comparative example. In each comparative example, one light guide is referred to as a light guide A, and the other light guide is referred to as a light guide B. A light source facing one end of the light guide A is referred to as a light source A. A light source facing one end of the light guide B is referred to as a light source B. A light source facing the other end of the light guide B is referred to as a light source C. A light source facing the other end of the light guide A is referred to as a light source D.

1. Comparative Example 1
As shown in FIG. 10, Comparative Example 1 is an example in which all the light sources are connected in series. In the connection method of the first comparative example, only one lighting control circuit for controlling turning on and off of the light source is required, and the number of lighting control circuits can be reduced.

  However, in the connection method of Comparative Example 1 shown in FIG. 10, when one light source fails in the open mode, all the light sources do not light. There is a disadvantage that the reading function can not be used just by failure of one light source in the open mode.

  Further, in the connection method of Comparative Example 1 shown in FIG. 10, there is a disadvantage that it is not possible to distinguish whether the light source has failed or the light amounts of the plurality of light sources are reduced when one light source breaks down in the short mode. .

  For example, when the light source B breaks down in the short mode, the pixel value of a pixel close to the light source B becomes darker in the image data of one line as compared with the case where the light source B breaks down. However, the light source A on the same side as the light source B in the main scanning direction is turned on. Therefore, the pixel value close to the light source B does not have a value corresponding to black. Therefore, it can not be clearly distinguished whether the light source B has failed or the light amounts of both the light source A and the light source B are reduced.

2. Comparative example 2
As shown in FIG. 11, Comparative Example 2 is an example in which one lighting control circuit is provided for one light source. In the connection method of Comparative Example 2, the light sources can be lit one by one. By checking whether each pixel value of the image data of a line is brighter than the pixel value at the time of turning off while turning on the light source one by one, it is possible to specify the light source not to be turned on.

  However, in the connection method of Comparative Example 2, the lighting control circuit is required for the number of light sources. Therefore, the manufacturing cost of the image reading apparatus 1 is increased. In addition, a large space for installing the lighting control circuit is required. In addition, there is a disadvantage that the number of wirings connecting the light source and the lighting control circuit is increased.

3. Comparative example 3
As shown in FIG. 12, in Comparative Example 3, two light sources at one end of each light guide are combined, two light sources at the other end of each light guide are combined, and a lighting control circuit is provided in combination. It is an example. The respective combined light sources are connected in series. FIG. 12 shows an example in which the light source A and the light source B facing one end of each light guide are connected in series, and the light sources C and D facing the other end are connected in series. Further, FIG. 12 shows an example in which the lighting control circuit A controls turning on / off of the light source A and the light source B, and the lighting control circuit B controls turning on / off of the light source C and the light source D. In this example, the number of lighting control circuits can be reduced compared to the case where the lighting control circuit is provided for each light source.

  However, in the connection method of Comparative Example 3, when one light source fails in the open mode, the incidence of light from one end or the other end of the light guide is eliminated. As a result, the image quality of the image data obtained by the reading is greatly reduced. For example, the image data is such that a certain width (a certain width at one end side or the other end side in the main scanning direction) from the end of the document is black. Therefore, there is a disadvantage that the reading function can not be used if only one light source fails in the open mode.

  Moreover, in the connection method of Comparative Example 3, when one light source fails in the short mode, there is a disadvantage that it can not be distinguished whether the light source has failed or the light amounts of the plurality of light sources are reduced. For example, when the light source B breaks down in the short mode, the pixel value of a pixel close to the light source B becomes darker than when it does not break down. However, the light source A which is on the same side (next side) as the light source B in the main scanning direction is turned on. Pixel values close to the light source B do not correspond to black. Therefore, it can not be clearly distinguished whether the light source B has failed or the light amounts of both the light source A and the light source B are reduced.

4. Comparative example 4
As shown in FIG. 13, Comparative Example 4 is an example in which the light sources facing one end of the light guide and the light sources facing the other end are combined and the respective light sources to be combined are connected in series. In FIG. 13, a light source A facing one end of the light guide A and a light source D facing the other end are connected in series, and a light source B facing the one end of the light guide B and a light source D facing the other end An example of connecting in series is shown. Further, FIG. 13 shows an example in which the lighting control circuit A controls turning on / off of the light source A and the light source D, and the lighting control circuit B controls turning on / off of the light source B and the light source C.

  In the connection method of Comparative Example 3, when one light source fails in the open mode, the irradiation of light from one of the light guides disappears. As a result, light is emitted to the document on the reading line from only one side in the left-right direction of the sub scanning direction. When light is irradiated from only one side in the sub scanning direction, shadows are formed on the unevenness, wrinkles, and steps of the document. As a result, the unevenness of the original, the wrinkles, and the shadow of the step can be read. It may be noticeable asperities, wrinkles, or shadows of steps, and the image quality of image data may be greatly reduced.

(Failure judgment of light source)
Next, an example of the flow of the failure determination of the light source in the image reading device 1 according to the embodiment will be described with reference to FIGS. 14 to 16. 14 and 15 are flowcharts illustrating an example of the flow of the failure determination of the light source in the image reading device 1 according to the embodiment. A series of flows are divided into FIG. 14 and FIG. FIG. 16 is a diagram showing an example of the determination result notification screen S1 according to the embodiment.

  The start of FIG. 14 is the time to start the failure determination of the light source. Failure inspection may be performed for inspection before factory shipment or before installation of the multifunction device 100. In this case, when the operation panel 22 is instructed to execute the failure determination of the light source, the failure determination is started. In addition, the failure determination may be performed when the main power supply of the multi-function device 100 is turned on, or when an instruction to execute a job such as copy or scan transmission is issued.

  First, the reading control unit 40 rotates the take-up motor 45 so that the image sensor 6 is at a position to read the white reference plate (white plate used for processing such as shading correction) provided in advance. Move 5 (step # 1). In other words, the position of the reading line is moved below the white reference plate. For example, the white reference plate is provided on the upper side of the transport reading contact glass 41 (see FIG. 2).

  The reading control unit 40 causes the first lighting circuit 91 to light the first light source 81 and the second light source 82 (step # 2). Thereby, current is supplied to the series circuit of the first light source 81 and the second light source 82. Next, the reading control unit 40 causes the image sensor 6 to perform reading and causes the image data generation unit 46 to generate image data of a line (step # 3).

  Based on the generated image data, the reading control unit 40 obtains a first determination value and a second determination value (step # 4). The first determination value is a value based on the pixel value of any pixel on one end side of the center of the generated image data in the main scanning direction. Specifically, the reading control unit 40 averages pixel values of a plurality of pixels at a predetermined position on one end side (of the first light guide 71) of the generated image data with respect to the center in the main scanning direction. A value is determined as a first determination value. For example, in the image data, the average value of the pixel values of each of the tens to hundreds of pixels is calculated from the top pixel (the first pixel) toward the center.

  The second determination value is a value based on the pixel value of any pixel on the other end side of the center of the main scanning direction in the generated image data. Specifically, the reading control unit 40 sets pixel values of a plurality of pixels at predetermined positions on the other end side (of the second light guide 72) of the generated image data with respect to the center in the main scanning direction. An average value is determined as a second determination value. For example, in the image data, the average value of the pixel values of each of the dozens to hundreds of pixels is determined from the end pixel (the rearmost pixel) toward the center.

  Subsequently, the reading control unit 40 causes the first lighting circuit 91 to extinguish the first light source 81 and the second light source 82 (step # 5). Next, the reading control unit 40 causes the second lighting circuit 92 to light the third light source 83 and the fourth light source 84 (step # 6). Thereby, current is supplied to the series circuit of the third light source 83 and the fourth light source 84. The reading control unit 40 causes the image sensor 6 to perform reading and causes the image data generating unit 46 to generate image data of a line (step # 7).

  Based on the generated image data, the reading control unit 40 obtains a third determination value and a fourth determination value (step # 8). The third determination value is a value based on the pixel value of one of the pixels on one end side of the center of the generated image data in the main scanning direction. Specifically, the reading control unit 40 calculates the average of pixel values of a plurality of pixels at a predetermined position on one end side (of the second light guide 72) of the generated image data with respect to the center in the main scanning direction. The value is determined as a third determination value. For example, in the image data, an average value of pixel values of each of tens to hundreds of pixels is calculated from the top pixel (the pixel at the first end side) toward the center.

  The fourth determination value is a value based on the pixel value of any pixel on the other end side of the center of the generated image data in the main scanning direction. Specifically, the reading control unit 40 sets pixel values of a plurality of pixels at predetermined positions on the other end side (of the first light guide 71) of the generated image data with respect to the center in the main scanning direction. An average value is determined as a fourth determination value. For example, in the image data, the average value of the pixel values of each of the dozens to hundreds of pixels is determined from the end pixel (the rearmost pixel) toward the center.

  Then, the reading control unit 40 causes the second lighting circuit 92 to turn off the third light source 83 and the fourth light source 84 (step # 9). Subsequently, the reading control unit 40 compares the first determination value, the second determination value, the third determination value, and the fourth determination value with a predetermined threshold (step # 10).

  The threshold is a value for determining whether or not the light source is broken. In this description, an example will be described in which the pixel value increases as the pixel receives a larger amount of light (brighter → larger pixel value, darker → smaller pixel value). Therefore, in the present description, the threshold is set to a value smaller than the first determination value, the second determination value, the third determination value, and the fourth determination value when there is no failure in the light source. Based on the comparison result with the threshold value, the reading control unit 40 determines the presence or absence of a failure of the light source and the failure mode, and when the failure is detected, identifies the failed light source (step # 11).

  Specifically, when all of the first determination value, the second determination value, the third determination value, and the fourth determination value are brighter (larger values) than the threshold, the reading control unit 40 determines that there is no failure of the light source. It is determined (step # 11).

  When the first determination value is brighter (larger) than the threshold value and the second determination value is the same as the threshold value or a value darker than the threshold value (below the threshold value), the second light source 82 is broken in the short mode It is determined (step # 11). This is because it is recognized that the first light source 81 is turned on and the second light source 82 is turned off.

  When the first determination value is equal to or darker than the threshold (is less than or equal to the threshold) and the second determination is brighter (larger) than the threshold, the first light source 81 breaks down in the short mode. It is determined that there is (step # 11). This is because it is recognized that the second light source 82 is turned on and the first light source 81 is turned off.

  The fourth light source 84 is broken in the short mode when the third determination value is brighter (larger) than the threshold value and the fourth determination value is equal to or less than the threshold value (less than the threshold value). It is determined (step # 11). This is because it is recognized that the third light source 83 is turned on and the fourth light source 84 is turned off.

  When the third determination value is equal to or darker than the threshold (is less than or equal to the threshold) and the fourth determination is brighter (larger) than the threshold, the third light source 83 breaks down in the short mode. It is determined that there is (step # 11). This is because it is recognized that the fourth light source 84 is turned on and the third light source 83 is turned off.

  When both of the first determination value and the second determination value are equal to or less than the threshold value (less than or equal to the threshold value), the light sources connected to the first lighting circuit 91 (the first light source 81 and the second light source 82 It is determined that the series circuit is broken in the open mode (step # 11). This is because it is recognized that neither the first light source 81 nor the second light source 82 is lit.

  When any of the third determination value and the fourth determination value is equal to or less than the threshold value (less than or equal to the threshold value), the light sources connected to the second lighting circuit 92 (third light source 83 and fourth light source 84 It is determined that the series circuit is broken in the open mode (step # 11). This is because it is recognized that neither the third light source 83 nor the fourth light source 84 is on.

  Then, the reading control unit 40 causes the display panel 24 to display the determination result (step # 12). If it is determined that a failure occurs, the reading control unit 40 may cause the display panel 24 to display a message indicating the failure mode and the light source identified as the failure. FIG. 15 shows an example of the determination result notification screen S1 displayed on the display panel 24. As shown in FIG. FIG. 15 shows an example of the determination result notification screen S1 when it is determined that the light source on one side in the sub scanning direction on the near side of the multi-function device 100 (image reading device 1) is broken.

  Thus, the image reading device 1 according to the embodiment includes the image sensor 6, the first light guide 71, the second light guide 72, the first light source 81, the second light source 82, the third light source 83, and the fourth light source. A light source 84, a first lighting circuit 91, and a second lighting circuit 92 are included. The image sensor 6 has a plurality of light receiving elements arranged in the main scanning direction. The first light guide 71 is provided along the main scanning direction, and is provided on one side in the sub scanning direction with respect to the reading line of the image sensor 6. The second light guide 72 is provided along the main scanning direction, and is provided on the other side of the reading line of the image sensor 6 in the sub scanning direction. The first light source 81 is provided to face one end of the first light guide 71. The second light source 82 is connected in series to the first light source 81 and is provided to face the other end of the second light guide 72. The third light source 83 is provided to face one end of the second light guide 72. The fourth light source 84 is connected in series to the third light source 83 and is provided to face the other end of the first light guide 71. The first lighting circuit 91 turns on and off the first light source 81 and the second light source 82. The second lighting circuit 92 turns on and off the third light source 83 and the fourth light source 84.

  Thus, even if the light source connected to one of the lighting circuits fails in the open mode, it is possible to irradiate the document with light over the entire main scanning direction while securing about half the amount of light before the failure. Therefore, there is no deterioration in image quality such that the content of the read original can not be identified. Therefore, even if a failure occurs in the light source, the degree of deterioration of the image quality can be suppressed. The reading function of the image reading device 1 is not completely lost and can be used until a procedure such as repair or replacement is performed.

  Furthermore, the light source at one end of a light guide and the light source at the other end of another light guide are connected in series (alike). Therefore, even if one of the light sources connected to one of the lighting circuits fails, the light source connected to the lighting circuit that is not broken causes light to enter each light guide. That is, even if the light source fails, the state in which all the light guides emit light is maintained, and the state in which light is emitted from only one side of the reading line is not reached. Therefore, even if the document is read in a state where the light source is broken, the image data in which the unevenness of the document, the wrinkles, and the shadow of the step are emphasized is not obtained. Therefore, the deterioration of the image quality can be suppressed.

  The image reading apparatus 1 according to the embodiment includes an image data generating unit 46 that generates image data based on the output of the image sensor 6 by reading, and a control unit (reading control unit 40) that determines a failure of each light source. . At the time of failure determination, the control unit causes the first lighting circuit 91 to turn on the first light source 81 and the second light source 82, and one of the generated image data on one end side with respect to the center in the main scanning direction. The first determination value based on the pixel value of the pixel is brighter than a predetermined threshold value, and the second determination value based on the pixel value of any pixel on the other end side from the center in the main scanning direction is the threshold value. When the value is equal to or darker than the threshold, it is determined that the second light source 82 is broken in the short mode, and the first determination value is equal to the threshold or is darker than the threshold and the second When the determination value is brighter than the threshold value, it is determined that the first light source 81 is broken in the short mode. This makes it possible to accurately detect that a failure has occurred in the short mode with the light source connected to the first lighting circuit 91. In addition, the failure in the short mode can accurately identify whether the first light source 81 or the second light source 82 is present.

  Further, at the time of failure determination, the control unit causes the second lighting circuit 92 to turn on the third light source 83 and the fourth light source 84, and any one of the generated image data is one end side than the center in the main scanning direction. The third determination value based on the pixel value of the pixel is brighter than a predetermined threshold value, and the fourth determination value based on the pixel value of any pixel on the other end side from the center in the main scanning direction is When the value is equal to or darker than the threshold, it is determined that the fourth light source 84 is broken in the short mode, and the third judgment value is equal to the threshold or is darker than the threshold. When the fourth determination value is brighter than the threshold value, it is determined that the third light source 83 is broken in the short mode. This makes it possible to accurately detect that a failure has occurred in the short mode with the light source connected to the second lighting circuit 92. In addition, it is possible to accurately identify whether the fourth light source 84 or the third light source 83 has failed in the short mode.

  Further, at the time of failure determination, the control unit controls the series connection of the first light source 81 and the second light source 82 when both of the first determination value and the second determination value are equal to the threshold value or darker than the threshold value. When it is determined that the circuit is broken in the open mode, and both the third determination value and the fourth determination value are equal to the threshold value or darker than the threshold value, the fourth light source 84 and the third light source 83 It is determined that the series circuit of is broken in the open mode. This makes it possible to accurately detect that an open mode failure has occurred. In addition, it is possible to identify a series circuit (light source) in which an open mode failure has occurred.

  Further, at the time of failure determination, the control unit obtains, as a first determination value, an average value of pixel values of a plurality of pixels at a predetermined position on one end side of the center of the main scanning direction among generated image data. Among the generated image data, an average value of pixel values of a plurality of pixels at a predetermined position on the other end side with respect to the center in the main scanning direction is determined as a second determination value, and in the generated image data An average value of pixel values of a plurality of pixels at a predetermined position on one end side of the center of the image is determined as a third determination value, and the generated image data is predetermined on the other end side from the center in the main scanning direction. An average value of pixel values of a plurality of pixels at the specified position is determined as a fourth determination value. Thus, each determination value can be determined based on the average value of a plurality of pixels. The influence of noise on pixel values can be reduced by averaging, and appropriate determination values can be determined.

  Further, the total number of the first light guide 71 and the second light guide 72 is two or more. As a result, even when light sources are provided at both ends of the light guide and a plurality of light sources are provided, the failure mode of each light source and the position of the failed light source can be accurately determined.

  The image forming apparatus (MFP 100) according to the embodiment includes the image reading apparatus 1 according to the embodiment. According to this configuration, it is possible to provide an image forming apparatus having the effects of the image reading apparatus 1 according to the embodiment.

  As mentioned above, although embodiment of this invention was described, the range of this invention is not limited to this, A various change can be added and implemented in the range which does not deviate from the main point of invention. For example, in the above embodiment, an example in which one side is the left side of the reading line and the other side is the right side of the reading line in the sub-scanning direction has been described, but left and right may be reversed. Further, although an example in which one end side is the front end of the main scanning direction (each light guide) and the other end side is the rear end of the main scanning direction (each light guide) has been described, back and forth may be reversed.

  The present invention is applicable to an image reading apparatus and an image forming apparatus provided with the same.

100 multifunction device (image forming apparatus) 1 image reading device 40 reading control unit (control unit) 46 image data generating unit 6 image sensor 71 first light guide 72 second light guide 81 first light source 82 second light source 83 second light source 3 light source 84 fourth light source 91 first lighting circuit 92 second lighting circuit

Claims (7)

An image sensor in which a plurality of light receiving elements are arranged in the main scanning direction;
A first light guide provided along the main scanning direction and provided on one side in the sub scanning direction with respect to the reading line of the image sensor;
A second light guide provided along the main scanning direction and provided on the other side in the sub scanning direction with respect to the reading line of the image sensor;
A first light source provided facing one end of the first light guide;
A second light source connected in series with the first light source and facing the other end of the second light guide;
A third light source provided facing one end of the second light guide;
A fourth light source connected in series to the third light source and facing the other end of the first light guide;
A first lighting circuit that turns on / off the first light source and the second light source;
An image reading apparatus comprising: a second lighting circuit which turns on and off the third light source and the fourth light source. An image data generation unit that generates image data based on the output of the image sensor by reading;
Including a control unit that determines the failure of each light source,
At the time of the failure judgment,
The control unit causes the first lighting circuit to turn on the first light source and the second light source, and the pixel value of any pixel on one end side of the center of the main scanning direction in the generated image data. The first determination value based on is brighter than a predetermined threshold, and the second determination value based on the pixel value of any pixel on the other end side from the center in the main scanning direction is equal to the threshold When it is determined that the second light source is broken in the short mode when there is a certain value or a value darker than the threshold value, the first determination value is a value equal to the threshold value or a value darker than the threshold value The image reading apparatus according to claim 1, wherein when the second determination value is brighter than the threshold value, it is determined that the first light source is broken in the short mode. At the time of the failure judgment,
The control unit causes the second lighting circuit to turn on the third light source and the fourth light source, and a pixel value of any pixel on one end side of the center of the main scanning direction among the generated image data. The third determination value based on is brighter than a predetermined threshold, and the fourth determination value based on the pixel value of any pixel on the other end side from the center in the main scanning direction is equal to the threshold When it is determined that the fourth light source is broken in the short mode when there is a certain value or a value darker than the threshold value, the third determination value is a value equal to the threshold value or a value darker than the threshold value The image reading apparatus according to claim 2, wherein when the fourth determination value is brighter than the threshold value, it is determined that the third light source is broken in the short mode. At the time of the failure judgment,
The control unit is configured to connect a series circuit of the first light source and the second light source when both the first determination value and the second determination value are equal to the threshold value or a value darker than the threshold value. The fourth light source and the fourth light source are determined to be defective in the open mode, and when the third determination value and the fourth determination value are both equal to the threshold value or darker than the threshold value. 4. The image reading apparatus according to claim 3, wherein it is determined that the series circuit of three light sources is broken in the open mode. At the time of the failure judgment,
The control unit determines an average value of pixel values of a plurality of pixels at a predetermined position on one end side of the center of the main scanning direction among the generated image data as the first determination value, and the generated image data An average value of pixel values of a plurality of pixels at a predetermined position on the other end side with respect to the center in the main scanning direction is calculated as the second determination value, and the generated image data is determined more than the center in the main scanning direction. An average value of pixel values of a plurality of pixels at a predetermined position on one end side is determined as the third determination value, and of the generated image data at a predetermined position on the other end side with respect to the center in the main scanning direction. 5. The image reading apparatus according to claim 3, wherein an average value of pixel values of a plurality of pixels is determined as the fourth determination value.   The image reading apparatus according to any one of claims 1 to 5, wherein a total number of the first light guide and the second light guide is two or more.   An image forming apparatus comprising the image reading apparatus according to any one of claims 1 to 6.

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