Image reading device and image forming device

Abstract

To provide an image reading device and an image forming apparatus that prevent a shading correction error due to temperature fluctuation.SOLUTION: An image reading device 100 has: irradiation means that irradiates a document with light; a first light guide member that guides light reflected on the document; output means that outputs a read signal obtained from the reflected light; a reference member for correcting shading in the read signal; correction means that outputs a read image obtained by correcting the shading in the read signal of the document by using correction data obtained from the read signal of the reference member; and control means that controls the timing of irradiation performed by the irradiation means and the timing of output performed by the output means. Before the output means outputs read signals of the document and the reference member, the control means heats the first light guide member with the light radiated from the irradiation means. The correction means corrects the shading in the read signal of the document output from the output means while the first light guide member is heated by using the correction data obtained while the first light guide member is heated.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an image reading device and an image forming device. [Background technology]

[0002] In a conventional image reading device that outputs a scanned image of a document, a technique is known in which shading in the scanned image is corrected using correction data obtained from a read signal of a reference member. Here, shading refers to unevenness in brightness.

[0003] As a technique for correcting the above-mentioned shading, a technique has been disclosed in which power consumption is controlled to suppress correction errors according to the temperature characteristics of the image sensor, correction data is acquired while the temperature of the image sensor is raised, and then the shading of the image of a document read by the image sensor is corrected using the correction data (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology of Patent Document 1, there is a concern that shading correction errors may occur due to temperature fluctuations in the image reading device.

[0005] An object of the present invention is to suppress shading correction errors caused by temperature fluctuations in an image reading device. [Means for solving the problem]

[0006] an output unit configured to output a read signal obtained from the reflected light guided by the first light guide member; a reference member configured to correct shading in the read signal; a correction unit configured to output the read image in which the shading in the read signal of the document has been corrected using correction data obtained from the read signal of the reference member output from the output unit; and a control unit configured to control irradiation timing by the irradiation unit and output timing by the output unit, wherein the control unit heats the first light guide member with the light irradiated from the irradiation unit before the output unit outputs the read signals of the document and the reference member, respectively; and the correction unit corrects the shading in the read signal of the document output from the output unit when the first light guide member is heated, using the correction data obtained when the first light guide member is heated. The control means heats the first light guide member until a deformation amount of the first light guide member due to heating is saturated. do. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress shading correction errors caused by temperature fluctuations in an image reading device. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of an image reading apparatus according to a first embodiment. [Figure 2] 1 is a block diagram showing an example of the configuration of an image reading apparatus according to a first embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of the configuration of a first reading unit according to the first embodiment. [Figure 4] 10A and 10B are diagrams illustrating an example of shading correction using a first reading roller. [Figure 5] FIG. 2 is a block diagram illustrating an example of the functional configuration of a controller according to the first embodiment. [Figure 6]FIG. 4 is a flowchart of a first example of the operation of the image reading apparatus according to the first embodiment. [Figure 7] FIG. 10 is a flowchart of a second example of the operation of the image reading apparatus according to the first embodiment. [Figure 8] FIG. 10 is a block diagram illustrating an example of the functional configuration of a controller according to a second embodiment. [Figure 9] FIG. 10 is a diagram illustrating an example of the configuration of an image forming apparatus according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An image reading device and an image forming device according to an embodiment of the present invention will be described in detail with reference to the drawings. However, the following embodiments are merely illustrative of an image reading device and an image forming device embodying the technical concept of the present embodiment, and are not limited thereto. Furthermore, unless otherwise specified, the dimensions, materials, shapes, and relative locations of components described in the embodiments are merely illustrative examples and are not intended to limit the scope of the present invention. Note that the size, positional relationships, etc. of components shown in each drawing may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate the same or similar components, and detailed descriptions will be omitted as appropriate.

[0010] [First embodiment] <Configuration Example of Image Reading Device 100> The configuration of an image reading device 100 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a diagram illustrating the configuration of the image reading device 100, and is a cross-sectional view of the image reading device 100 viewed from a direction along the rotation axis of a transport roller used to transport a document. Figure 2 is a block diagram illustrating the configuration of the image reading device 100.

[0011] The image reading device 100 reads an original 1 to be read while transporting the original 1 at a predetermined speed in a transport direction m, and outputs a read image which is an image obtained by reading the original 1. In this embodiment, the image reading device 100 has a function of an ADF (Auto Document Feeder), which is an automatic document feeder.

[0012] As shown in FIG. 1, the image reading device 100 mainly includes a document placement section A, a separation and feeding section B, a registration section C, an inversion section D, a first reading and conveying section E, a second reading and conveying section F, a paper discharge section G, and a stacking section H.

[0013] The document placement section A is a section where the document 1 to be read is placed. The document 1 may be a single document, or a stack of multiple documents. The document placement section A includes a document table 2, a placement feeler 4, a placement sensor 5, a bottom plate HP sensor 6, and document length detection sensors 30 and 31. The document table 2 includes a movable document table 3 that can move to place the document 1 according to the size of the document 1.

[0014] The original 1 is placed on the original table 2 with one original surface facing vertically upward, for example. Both ends of the original 1 in a direction intersecting with the conveying direction m are pressed and positioned by side guides. A placement feeler 4 and a placement sensor 5 detect that the original 1 has been placed on the original table 2 and output a placement detection signal.

[0015] The document length detection sensors 30 and 31 detect the length of the document 1 placed on the document table 2 in the conveying direction m, and output a length detection signal. This length detection signal is used to determine whether the document 1 placed on the document table 2 is placed vertically or horizontally. The document length detection sensors 30 and 31 are positioned so as to be able to detect the document length.

[0016] Each of the document length detection sensors 30 and 31 is a reflective sensor that outputs an electrical signal according to the intensity of reflected light of irradiated light, or an actuator-type sensor that can detect the length of even a single document 1. The bottom plate HP sensor 6 detects the HP of the bottom plate, i.e., the initial position.

[0017] The movable original table 3 can be moved in the direction of the arrow of the first movable direction 51 by a bottom plate lifting motor 105 (see FIG. 2). The movable original table 3 is lifted so that the top surface of the original 1 comes into contact with the pickup roller 7, for example, when the bottom plate lifting motor 105 rotates forward in response to a placement detection signal from the placement feeler 4 and the placement sensor 5.

[0018] Separation and feeding section B is a component that has the function of feeding the originals 1 placed in original placement section A. When the originals 1 are a stack of originals, separation and feeding section B separates and feeds the originals one by one from the stack. Separation and feeding section B has a pickup roller 7, a table paper feed position sensor 8, a paper feed belt 9, and a reverse roller 10.

[0019] The pickup roller 7 is moved in the direction of the arrow in the second movable direction 52 by a pickup motor 101 (see FIG. 2) and a cam mechanism, and is pressed by the upper surface of the document 1 which is moved by the movable document table 3. The table paper feed position sensor 8 outputs a position detection signal which indicates the position of the pickup roller 7.

[0020] The paper feed belt 9 is driven by the forward rotation of a paper feed motor 102 (see FIG. 2). The reverse roller 10 is driven to rotate in the direction opposite to the conveying direction m (clockwise) in response to the forward rotation of the paper feed motor 102. By driving the paper feed belt 9 and the reverse roller 10, the separation and feeding unit B can separate the topmost document 1 from the document 1 below it and feed only the topmost document 1.

[0021] More specifically, the reverse roller 10 is in contact with the paper feed belt 9 at a predetermined pressure, and when in direct contact with the paper feed belt 9 or when in contact with the paper feed belt 9 via one sheet of original 1, the reverse roller 10 rotates counterclockwise in response to the rotation of the paper feed belt 9. The co-rotation force is preset to be lower than the torque of the torque limiter, and if two or more sheets of original 1 enter between the paper feed belt 9 and the reverse roller 10, the reverse roller 10 rotates clockwise, which is its normal driving direction, and acts to push back the excess sheets of original 1, thereby preventing double feeding. The sheets of original 1 separated by the paper feed belt 9 and the reverse roller 10 are transported by the paper feed belt 9 along the transport direction m toward the registration section C.

[0022] The registration unit C is a component that has the function of primarily abutting the fed document 1 and the function of pulling out and transporting the document 1 after abutting. The registration unit C includes an abutment sensor 11, a pull-out roller 12, and a document width sensor 13.

[0023] The leading edge of the document 1 conveyed by the separation and feeding unit B is detected by the abutment sensor 11, and the document is further conveyed until it abuts against the stopped pull-out roller 12. Thereafter, the document 1 is conveyed a predetermined distance in response to a collision detection signal from the abutment sensor 11. Thereafter, the document 1 stops in a state where it is pressed against the pull-out roller 12 with a predetermined deflection. When the document 1 stops, the leading edge of the document 1 enters the nip of the roller pair included in the pull-out roller 12, and skew correction of the leading edge is performed.

[0024] The pull-out roller 12 is driven by the reverse rotation of the paper feed motor 102 (see FIG. 2), and transports the skew-corrected original 1 to the position of the intermediate roller 14. When the paper feed motor 102 is reversed, the pull-out roller 12 and the intermediate roller 14 are driven, but the pickup roller 7 and paper feed belt 9 are not driven.

[0025] A plurality of document width sensors 13 are arranged along the width direction of the document 1, and detect the length along the width direction of the document 1 transported by the pull-out rollers 12. The length along the transport direction m of the document 1 is detected based on the detection results of the abutment sensors 11 at the leading and trailing ends of the document 1.

[0026] The reversing unit D is a component that has the function of reversing the transported original 1 and transporting the surface of the original 1 toward the reading side (the side of the first reading and transporting unit E in the figure). The reversing unit D has an intermediate roller 14. The intermediate roller 14 is configured to include a roller pair, and the roller pair sandwiches and transports the original 1.

[0027] The original 1 is transported from the registration section C to the reversal section D by the drive of the pull-out roller 12 and the intermediate roller 14. The transport speed in the registration section C is predetermined to be faster than the transport speed in the first reading and transport section E. This allows the processing time for sending the original 1 to the first reading and transport section E to be shortened.

[0028] The first reading and conveying unit E is a component that has the function of reading one side (hereinafter referred to as the "front side") of the conveyed original 1 from the opposite side of the contact glass to the original 1. The first reading and conveying unit E outputs a read image of the front side of the original 1.

[0029] The first reading conveying unit E has a first reading entrance sensor 15, a first reading entrance roller 16, a registration sensor 17, a first reading roller 19, a first reading unit 20, and a first reading exit roller 23. When the leading edge of the document 1 in the conveying direction m is detected by the first reading entrance sensor 15, the first reading conveying unit E starts to decelerate the conveying speed of the document 1 to make it approximately equal to the reading speed before the leading edge of the document 1 enters the nip of the roller pair of the first reading entrance roller 16. At the same time, the first reading conveying unit E drives the reading motor 103 (see FIG. 2) in the forward direction to drive the first reading entrance roller 16 and the first reading exit roller 23.

[0030] When the registration sensor 17 detects the leading edge of the document 1 in the conveying direction m, the first reading and conveying unit E decelerates while the document 1 is conveyed a predetermined distance, and temporarily stops before entering the first reading unit 20.

[0031] Thereafter, in response to a reading start signal, the first reading conveying unit E conveys the stopped original document 1 while accelerating it so that the leading edge of the original document 1 in the conveying direction m reaches a predetermined conveying speed by the time it reaches the first reading unit 20.

[0032] The first reading and conveying unit E reads the surface of the original 1 from the time when the leading end of the original 1 in the conveying direction m enters the position of the first reading unit 20 until the trailing end of the original 1 in the conveying direction m leaves the position of the first reading unit 20, and outputs a signal indicating the read image.

[0033] The first reading roller 19 prevents the document 1 from floating up when read by the first reading unit 20, and also functions as a reference member for acquiring shading correction data for correcting shading in the image read by the first reading unit 20.

[0034] When only one side of the document 1 is to be read, the first reading and conveying unit E conveys the document 1 that has passed through it to the paper discharge unit G via the second reading and conveying unit F. At this time, when the first reading and conveying unit E detects the leading edge of the document 1 in the conveying direction m using the paper discharge sensor 24, it drives the paper discharge motor 104 (see FIG. 2) in the forward direction to rotate the paper discharge roller 28 counterclockwise.

[0035] The first reading and conveying unit E also counts the drive pulses of the discharge motor 104 from the time when the discharge sensor 24 detects the leading edge of the original 1 in the conveying direction m. The first reading and conveying unit E decelerates the conveying speed of the discharge motor 104 just before the trailing edge of the original 1 in the conveying direction m exits the nip of the roller pair of the discharge roller 28. In this way, the first reading and conveying unit E controls the original 1 to be discharged onto the discharge tray 29 so that it does not jump out of the discharge tray 29.

[0036] The second reading and conveying section F is a component that has the function of reading the other side (hereinafter referred to as the "rear side") of the original 1. The second reading and conveying section F outputs a read image of the rear side of the original 1. The second reading and conveying section F has a paper discharge sensor 24, a second reading section 25, a second reading roller 26, a second reading exit roller 27, and a paper discharge roller 28.

[0037] The configuration of the second reading unit 25 is the same as that of the first reading unit 20, and only the placement position differs from that of the first reading unit 20 in order to read the back side of the document 1. The configuration and function of the second reading roller 26 are the same as that of the first reading roller 19, and only the placement position differs from that of the first reading unit 20 in order to read the back side of the document 1. However, the configuration of the second reading unit 25 may be different from that of the first reading unit 20, and the configuration of the second reading roller 26 may be different from that of the first reading roller 19.

[0038] When reading the back side of the original 1, the second reading and conveying unit F counts the driving pulses of the reading motor 103 (see FIG. 2) after the leading edge of the original 1 in the conveying direction m is detected by the paper discharge sensor 24.

[0039] The second reading and conveying unit F reads the back side of the original 1 from the time when the leading end of the original 1 in the conveying direction m enters the position of the second reading unit 25 until the trailing end of the original 1 in the conveying direction m exits the position of the second reading unit 25, and outputs a read image signal.

[0040] The paper discharge section G is a section for discharging the document 1 after both sides have been read to the outside of the device.

[0041] The stacking section H is a section for stacking and holding the originals 1 after reading has been completed.

[0042] 2, the image reading device 100 includes a controller 300 and an operation unit 106. The controller 300 and the operation unit 106 are electrically connected via an interface 107. The controller 300 controls the operation of the image reading device 100.

[0043] The controller 300 is electrically connected to the registration sensor 17, the positioning sensor 5, the paper discharge sensor 24, the collision sensor 11, the document width sensor 13, the first reading entrance sensor 15, the table paper feed position sensor 8, and the bottom plate HP sensor 6, and inputs the detection signals or detection signals from each sensor.

[0044] The controller 300 is also electrically connected to the first reading unit 20, the second reading unit 25, the pickup motor 101, the paper feed motor 102, the reading motor 103, the paper discharge motor 104, the bottom plate lifting motor 105, and the like.

[0045] The controller 300 controls the operations of the first reading unit 20 and the second reading unit 25, and receives signals representing read images from the first reading unit 20 and the second reading unit 25, respectively.

[0046] The controller 300 also controls the driving of the pickup motor 101 , the paper feed motor 102 , the reading motor 103 , the paper discharge motor 104 and the bottom plate lifting motor 105 .

[0047] <Configuration example of first reading unit 20> 3 is a diagram showing an example of the configuration of the first reading unit 20. The first reading unit 20 has a light emitting unit 201, a light guide 202, a rod lens array 203, and a light receiving unit 204. The first reading unit 20 is, for example, a CIS (Contact Image Sensor), which is a contact type image sensor, but is not limited to this and may have a configuration including a reduction optical system.

[0048] The light-emitting unit 201 is an example of a light-emitting means. The light-emitting unit 201 includes a first light-emitting unit 201a and a second light-emitting unit 201b. The first light-emitting unit 201a is provided at one end of the light guide 202 in a width direction n that is substantially perpendicular to the conveying direction m, and emits light toward the one end. The second light-emitting unit 201b is provided at the other end of the light guide 202 in the width direction n, and emits light toward the other end.

[0049] For example, the first light-emitting unit 201a and the second light-emitting unit 201b are each an LED (Light Emitting Diode). However, the light-emitting unit 201 is not limited to an LED as long as it can emit light, and the number of light-emitting units is not limited to two.

[0050] Distance d is the distance between first light-emitting unit 201a and one end of light guide 202 in width direction n. Distance d is also the distance between second light-emitting unit 201b and the other end of light guide 202 in width direction n. There are no particular limitations on distance d, and image reading device 100 can set distance d appropriately depending on its application, specifications, etc.

[0051] The light guide 202 is an example of a second light guide member that guides the light emitted from the light emitting unit 201 to the document 1. The light guide 202 is a columnar member whose longitudinal direction is the width direction n, and is a light-transmitting member that can guide light inside.

[0052] The light emitted from each of the first light-emitting portion 201a and the second light-emitting portion 201b and incident from both ends of the light guide 202 in the width direction n is guided along the width direction n while repeatedly undergoing total reflection inside the light guide 202. In the process of being guided, the light that is incident on the main surface (surface along the longitudinal direction) of the light guide 202 at an incident angle smaller than the critical angle is emitted from inside the light guide 202 to the outside.

[0053] The light-emitting unit 201 and the light guide 202 constitute an irradiation means for irradiating the original 1 with irradiation light Ls. The light-emitting unit 201 and the light guide 202 can irradiate the original 1 with light that is emitted from the inside of the light guide 202 to the outside and that is emitted toward the original 1 as irradiation light Ls. The irradiation light Ls is a line-shaped light that extends along the width direction n.

[0054] The rod lens array 203 is an example of a first light guiding member that guides the reflected light Lr from the document 1, which is emitted from the light emitting unit 201 and the light guiding body 202. The rod lens array 203 includes a plurality of rod lenses 202a aligned along the width direction n.

[0055] Each of the rod lenses 203a is a rod-shaped, equal-magnification imaging optical element through which light can be guided. For example, the rod lenses 203a are gradient index lenses, but may also be refractive lenses or diffractive lenses.

[0056] The reflected light Lr incident on each of the rod lenses 203a from the original 1 side is guided inside the rod lens 203a and emitted on the opposite side of the rod lens array 203 from the original 1. The light emitted from the rod lens array 203 is incident on a light receiving unit 204 provided on the opposite side of the rod lens array 203 from the original 1, and is received by the light receiving unit 204.

[0057] The light receiving unit 204 is an example of an output means that outputs a read signal Is obtained from the reflected light Lr guided by the rod lens array 203. The light receiving unit 204 is, for example, a line-type image sensor in which a plurality of light receiving elements such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) are aligned as pixels along the width direction n, and outputs a one-dimensional read signal Is for forming a one-dimensional read image.

[0058] The light receiving unit 204 may output a monochrome read signal Is for forming a monochrome read image, or may output a color read signal Is for forming a color read image. The light receiving unit 204 is not limited to a line type image sensor, but may be an area type image sensor that outputs a two-dimensional read signal Is for forming a two-dimensional read image.

[0059] The plurality of light receiving elements included in the light receiving unit 204 output an electrical signal corresponding to the light intensity of the received light as a read signal Is. The light receiving unit 204 can capture a digital line image with the longitudinal direction being the width direction by connecting, in the width direction, digital signals obtained by A / D (Analog / Digital) converting the read signals output from the respective light receiving elements.

[0060] Although the configuration of the first reading unit 20 has been described above, the second reading unit 25 has the same configuration and function as the first reading unit 20. When reading with the second reading unit 25, the second reading roller 26 is used as a reference member. Although the first reading unit 20 will be mainly described below, the same description as for the first reading unit 20 can also be applied to the second reading unit 25.

[0061] <Shading correction example> Here, the read signal Is output from the light receiving unit 204 may contain uneven brightness called shading. The shading is uneven brightness that is unrelated to the surface of the document 1 that is the target of reading by the image reading device 100, and therefore it becomes an error in reading the document 1 by the image reading device 100.

[0062] Shading can occur for a variety of reasons, including uneven brightness along the width direction n of the illumination light Ls irradiated onto the document 1 from the light-emitting unit 201 and the light guide 202, uneven brightness along the width direction n of the light guided by the rod lens array 203 and incident on the light-receiving unit 204, and differences in characteristics among the multiple light-receiving elements included in the light-receiving unit 204. Causes of shading due to the rod lens array 203 include, for example, differences in characteristics among the multiple rod lenses 203a, or unevenness in the amount of guided light due to the joints between adjacent rod lenses 203a.

[0063] The image reading device 100 corrects the shading using the first reading roller 19. The first reading roller 19 is an example of a reference member for correcting shading in the read signal Is output from the light receiving unit 204. The first reading roller 19 is a rotating body configured to have a predetermined density distribution along the width direction n. The predetermined density distribution is, for example, a substantially uniform white density distribution along the width direction n, or a substantially uniform black density distribution along the width direction. However, the predetermined density distribution is not limited to these, and any predetermined density distribution may be used. The image reading device 100 can also provide the first reading roller 19 with multiple different density distributions and correct shading using correction data obtained using these multiple density distributions.

[0064] Fig. 4 is a diagram illustrating an example of shading correction using the first reading roller 19. As shown in Fig. 4, when performing shading correction, the image reading device 100 places the first reading roller 19 in place of the original 1 at a position where the irradiation light Ls is irradiated from the light emitting unit 201 and the light guide 202.

[0065] Since the first reading roller 19 also functions as a component that prevents the original 1 from floating up when reading the original 1, the state of the image reading device 100 when performing shading correction can also be said to be a state in which the original 1 has been removed from between the first reading unit 20 and the first reading roller 19.

[0066] 4, the first reading unit 20 reads the predetermined density distribution of the first reading roller 19 and outputs a read signal Ic of the first reading roller 19 from the light receiving unit 204. By subtracting the predetermined density distribution of the first reading roller 19 from this read signal Ic, correction data for correcting shading is obtained.

[0067] The image reading device 100 stores the obtained correction data in a storage unit and corrects shading by subtracting the correction data from a line image obtained from the read signal Is of the original 1. The image reading device 100 can output a one-dimensional read image in which shading in the read signal Is has been corrected. Note that the image reading device 100 can also output a two-dimensional read image by joining, along the conveyance direction m, multiple line images captured of the original 1 being conveyed along the conveyance direction m.

[0068] <Example of functional configuration of controller 300> 5 is a block diagram showing an example of the functional configuration of the controller 300. The controller 300 is an example of a control means that controls the timing of irradiation by the light emitting unit 201 and the light guide 202 and the timing of output by the light receiving unit 204.

[0069] As shown in FIG. 5, the controller 300 includes an irradiation timing control unit 301, a reading timing control unit 302, a correction unit 303, a storage unit 304, an input / output unit 305, and a power supply control unit 307.

[0070] The controller 300 realizes the functions of the irradiation timing control unit 301, the reading timing control unit 302, the correction unit 303, the input / output unit 305, and the power supply control unit 307 by a CPU (Central Processing Unit) expanding a program stored in a memory such as a ROM (Read Only Memory) into a work area such as a RAM (Random Access Memory) and executing the program. The controller 300 may realize at least a portion of the functions of the above components by an electric circuit, or may realize the functions by using a plurality of programs or electric circuits. The controller 300 may realize the functions of the storage unit 304 by a storage device such as an HDD (Hard Disk Drive).

[0071] At least some of the functions of the controller 300 may be performed by other components such as the first reading unit 20.

[0072] The irradiation timing control unit 301 controls the irradiation timing of the light emitting unit 201 and the light guide 202. For example, the irradiation timing control unit 301 controls the irradiation timing of the irradiation light Ls by the light emitting unit 201 and the light guide 202 by outputting an irradiation control signal St to the first reading unit 20 via the input / output unit 305.

[0073] More specifically, the irradiation timing control unit 301 outputs an irradiation control signal St by switching logic through register access from the CPU to the light emitting unit 201, and controls the emission and non-emission of the light emitting unit 201 to control the emission timing of the irradiation light Ls.

[0074] The reading timing control unit 302 controls the output timing of the light receiving unit 204. For example, when reading the original 1, the reading timing control unit 302 controls the output timing of the reading signal Is by the light receiving unit 204 by outputting a reading control signal Sr to the first reading unit 20 via the input / output unit 305. When acquiring correction data, the reading timing control unit 302 controls the output timing of the reading signal Ic by the light receiving unit 204 by outputting a reading control signal Sr to the first reading unit 20 via the input / output unit 305.

[0075] More specifically, the read timing control unit 302 controls the read timing by using the clock signal and line synchronization signal supplied to the light receiving unit 204 as a read control signal Sr and controlling the clock signal and line synchronization signal by accessing the register from the CPU.

[0076] The correction unit 303 is an example of a correction means that corrects shading using correction data 306. The correction data 306 is obtained from the read signal Ic of the first read roller 19 output from the light receiving unit 204, and is stored in advance in the storage unit 304. When the read signal Is of the original 1 is output from the light receiving unit 204, the correction unit 303 acquires the correction data 306 by referring to the storage unit 304, and can output the read signal Ic obtained by correcting the read signal Is using the correction data 306 via the input / output unit 305 as a one-dimensional read image.

[0077] Here, the correction data 306 is acquired and stored in the storage unit 304 before the read signal Is of the original 1 is output from the light receiving unit 204. However, while the read signal Is of the original 1 is being output by the light receiving unit 204, the rod lens array 203 and the light guide 202 are heated by the light emitted by the light emitting unit 201, and the amount of thermal deformation thereof may change over time. In other words, the amount of thermal deformation of the rod lens array 203 and the light guide 202 may change over time due to temperature fluctuations of the image reading device 100 over time.

[0078] For example, if the rod lens array 203 expands and contracts along the width direction n due to heating and the amount of deformation changes over time, the shading when the correction data 306 is acquired will differ from the shading when the original 1 is read. This difference makes it impossible for the image reading device 100 to appropriately correct the shading when the original 1 is read.

[0079] Similarly, if the light guide 202 expands and contracts along the width direction n due to heating and the amount of deformation changes over time, the shading when the correction data 306 is acquired will differ from the shading when the original 1 is read. This difference makes it impossible for the image reading device 100 to appropriately correct the shading when the original 1 is read.

[0080] In this embodiment, the controller 300 heats the rod lens array 203 with the irradiation light Ls emitted from the light emitting unit 201 and the light guide 202 before the light receiving unit 204 outputs the reading signal Is of the original 1 and the reading signal Ic of the first reading roller 19, respectively.

[0081] More specifically, when acquiring the correction data 306, the controller 300 controls the first reading unit 20 so that the light emitting unit 201 and the light guide 202 irradiate the rod lens array 203 with the irradiated light Ls before the light receiving unit 204 outputs the read signal Ic of the first reading roller 19. The rod lens array 203 is heated by the irradiation of the irradiated light Ls, and expands and contracts. The light guide 202 is heated by the irradiation of the light from the light emitting unit 201, and expands and contracts.

[0082] The light receiving unit 204 outputs a read signal Ic of the first read roller 19 when the rod lens array 203 and the light guide 202 are in an expanded or contracted state. Correction data 306 is acquired from the read signal Ic thus output and stored in the storage unit 304.

[0083] Furthermore, when acquiring a read image of the original 1, the controller 300 controls the first reading unit 20 so that the light emitting unit 201 and the light guide 202 irradiate the rod lens array 203 with the irradiated light Ls before the light receiving unit 204 outputs the read signal Is of the original 1. The rod lens array 203 is heated by the irradiation of the irradiated light Ls, and is deformed by expanding and contracting. Furthermore, the light irradiated from the light emitting unit 201 heats the light guide 202, and is deformed by expanding and contracting.

[0084] The light receiving section 204 outputs a read signal Is of the original 1 when the rod lens array 203 and the light guide 202 are in a state of expansion or contraction.

[0085] The correction unit 303 corrects the read signal Is of the original 1 output in a state in which the rod lens array 203 and the light guide 202 are heated, using the correction data 306 acquired in a state in which the rod lens array 203 and the light guide 202 are heated. The correction unit 303 outputs the corrected read signal Ic.

[0086] The power supply control unit 307 controls the supply of power Pw to the first reading unit 20 .

[0087] The image reading device 100 can acquire the correction data 306 in a state in which the rod lens array 203 and the light guide 202 are deformed by expansion and contraction due to heating, and can correct the read signal Is of the original 1. Therefore, the image reading device 100 can make the deformation states of the rod lens array 203 and the light guide 202 closer to each other between the time of acquiring the correction data 306 and the time of reading the original 1, thereby reducing the difference in the amount of deformation between them and suppressing shading correction errors.

[0088] For example, the controller 300 heats the rod lens array 203 and the light guide 202 until the deformation of each of the rod lens array 203 and the light guide 202 due to heating reaches saturation. Here, the state where the deformation reaches saturation refers to a state where the rod lens array 203 and the light guide 202 have each sufficiently deformed to a small extent. By doing so, the image reading device 100 can bring the deformation states of the rod lens array 203 and the light guide 202 closer together between the time when the correction data 306 is acquired and the time when the original 1 is read, thereby more effectively suppressing shading correction errors.

[0089] <Example of operation of image reading device 100> The operation of the image reading device 100 will be described with reference to Fig. 6 and Fig. 7. Fig. 6 and Fig. 7 are flowcharts showing an example of the operation of the image reading device 100, Fig. 6 being a first example and Fig. 7 being a second example.

[0090] In this embodiment, the image reading device 100 does not supply driving power to the first reading unit 20, and the first reading unit 20 is in an off state, except when a reading start instruction is received. The image reading device 100 starts the operation shown in Fig. 5 when a reading start instruction is received. The reading start instruction may be an operation input by a user via an operation unit of the image reading device 100, or may be a control signal input from an external device.

[0091] First, in step S61, the image reading device 100 supplies power Pw to the first reading unit 20 by the power supply control unit 307 in response to the received reading start instruction.

[0092] Next, in step S62, the image reading device 100 causes the irradiation timing control unit 301 to output an irradiation control signal St to the first reading unit 20 via the input / output unit 305. The light emitting unit 201 and the light guide 202 irradiate the first reading roller 19 with irradiation light Ls in response to the irradiation control signal St.

[0093] Next, in step S63, the image reading device 100 waits until the rod lens array 203 and the light guide 202 are heated by the irradiated light Ls and their temperatures increase. This waiting time is the time until the deformations of the rod lens array 203 and the light guide 202 reach saturation, and is a predetermined time.

[0094] Next, in step S64, the image reading device 100 causes the read timing control unit 302 to output a read control signal Sr to the first reading unit 20 via the input / output unit 305 after the temperatures of the rod lens array 203 and the light guide 202 have risen until the deformations of the rod lens array 203 and the light guide 202 have reached saturation. The light receiving unit 204 outputs a read signal Ic of the first reading roller 19 in response to the read control signal Sr. The image reading device 100 stores correction data 306 obtained from the read signal Ic in the storage unit 304.

[0095] Next, in step S65, the image reading device 100 outputs a reading control signal Sr to the first reading unit 20 via the input / output unit 305 using the reading timing control unit 302. The light receiving unit 204 outputs a reading signal Is of the original 1 in response to the reading control signal Sr. The image reading device 100 corrects the reading signal Is using correction data 306 acquired by referring to the storage unit 304, and can acquire a read image of the original 1 from the corrected reading signal Ic.

[0096] Subsequently, in step S66, the image reading device 100, through the controller 300, determines whether or not the next document 1 exists.

[0097] If it is determined in step S66 that the next document 1 exists (step S66, Yes), the image reading device 100 repeats the operations from step S65 onwards. On the other hand, if it is determined that the next document 1 does not exist (step S66, No), in step S67, the image reading device 100 stops the supply of power Pw to the first reading unit 20 by the power supply control unit 307. Thereafter, the image reading device 100 ends its operation.

[0098] In this manner, the image reading device 100 can correct the shading of the read image and output the read image obtained from the corrected read signal Ic.

[0099] Next, in the second example shown in FIG. 7, the image reading device 100 starts the operation of FIG.

[0100] First, in step S71, the image reading device 100 supplies power Pw to the first reading unit 20 by the power supply control unit 307 in response to a placement detection signal from the placement sensor 5.

[0101] Next, in step S72, the image reading device 100 causes the irradiation timing control unit 301 to output an irradiation control signal St to the first reading unit 20 via the input / output unit 305. The light emitting unit 201 and the light guide 202 irradiate the first reading roller 19 with irradiation light Ls in response to the irradiation control signal St.

[0102] Subsequently, in step S73, the image reading device 100 receives an instruction from the controller 300 to start reading the original 1.

[0103] Subsequently, in step S74, the image reading device 100 waits until the rod lens array 203 and the light guide 202 are heated by the irradiated light Ls and their temperatures increase.

[0104] The operations from step S75 onwards are the same as those from step S64 onwards in FIG. 6, and therefore a duplicated description will be omitted here.

[0105] In this way, the image reading device 100 can correct shading in the read image and output the read image obtained from the corrected read signal Ic. In the second example, the timing at which the original 1 is placed on the original placement unit A is used as a trigger to start heating the light emitting unit 201 and the light guide 202, thereby shortening the waiting time until the temperatures of the rod lens array 203 and the light guide 202 increase. As a result, it is possible to reduce shading correction errors while increasing productivity in reading the original 1.

[0106] <Effects of the image reading device 100> The effects of the image reading device 100 will be described.

[0107] Conventionally, image reading devices are known that correct shading in a read image. Shading correction is preferably performed each time a document is read, because the brightness of the light emitted from the light-emitting unit of the image reading device may change over time.

[0108] However, if shading correction is performed every time a document is read, the productivity of document reading may decrease because the correction data used to correct shading must be obtained more frequently during periods when the document is not being read (called paper intervals).

[0109] In particular, within an image reading device, when the reading position of the reference member used for shading correction and the reading position of the document differ in the document transport direction, the carriage carrying the reading unit must be moved back and forth multiple times between the reading position of the reference member and the reading position of the document, resulting in a more significant decrease in productivity.

[0110] Intermittent shading correction techniques are known that periodically generate correction data to prevent productivity declines in document scanning. However, conventional intermittent shading correction techniques cannot correct the effects of thermal deformation of light-guiding members, such as rod lens arrays or light guides, over time due to temperature fluctuations.

[0111] For example, in the case of a rod lens array, the rod lens array expands and contracts in the width direction intersecting the document transport direction, which may cause the positions of the multiple rod lenses included in the rod lens array and the positions of the multiple light receiving elements included in the light receiving unit to shift in the width direction. This may cause the peak position of the light intensity in shading to shift in the width direction between the correction data and the read signal from the light receiving unit, resulting in the occurrence of streak-like abnormal images such as black or white streaks extending in the transport direction in the read image.

[0112] On the other hand, in the case of a light guide, the direction of light emitted from the light guide may change over time due to the load imposed on the connection between the fixing member that fixes the light guide and the light guide due to deformation of the light guide. This causes the shading along the width direction to change over time, resulting in a difference in shading between the correction data and the read signal from the light receiving unit, and causing a shading correction error.

[0113] The image reading device 100 according to this embodiment includes a light-emitting unit 201 and a light guide 202 (illumination means) that irradiate an original 1 with irradiation light Ls (light), and a rod lens array 203 (first light guide member) that guides reflected light Lr from the original 1 of the irradiation light Ls irradiated from the light-emitting unit 201 and the light guide 202. The image reading device 100 also includes a light-receiving unit 204 (output means) that outputs a read signal Is obtained from the reflected light Lr guided by the rod lens array 203, and a first read roller 19 (reference member) that corrects shading in the read signal Is. The image reading device 100 further includes a correction unit 303 that uses correction data 306 obtained from the reading signal Is of the first reading roller 19 output from the light receiving unit 204 to output a reading signal Ic (read image) in which shading in the reading signal Is of the original 1 is corrected, and a controller 300 (control means) that controls the irradiation timing by the light emitting unit 201 and the light guide 202 and the output timing by the light receiving unit 204.

[0114] The controller 300 heats the rod lens array 203 with the irradiated light Ls emitted from the light emitting unit 201 and the light guide 202 before the light receiving unit 204 outputs the read signals Is of the original 1 and the first read roller 19. The correction unit 303 uses correction data 306 obtained when the rod lens array 203 is heated to correct shading in the read signals Is of the original 1 output from the light receiving unit 204 when the rod lens array 203 is heated.

[0115] The image reading device 100 acquires the correction data 306 when the rod lens array 203 and the light guide 202 are in a state where they have expanded or contracted due to heating, and can correct the read signal Is of the original document 1 using this correction data 306. Therefore, the image reading device 100 can make the deformation states of the rod lens array 203 and the light guide 202 closer to each other between the time when the correction data 306 is acquired and the time when the original document 1 is read. As a result, the difference in the amount of deformation of the rod lens array 203 and the light guide 202 between the time when the correction data 306 is acquired and the time when the original document 1 is read can be reduced, and shading correction errors due to temperature fluctuations in the image reading device 100 can be suppressed.

[0116] For example, it is preferable that the controller 300 heats the rod lens array 203 and the light guide 202 until the deformation amounts of the rod lens array 203 and the light guide 202 due to heating reach saturation. By doing so, the image reading device 100 can make the deformation states of the rod lens array 203 and the light guide 202 closer to each other between the time when the correction data 306 is acquired and the time when the original 1 is read, and can further suppress shading correction errors due to temperature fluctuations in the image reading device 100.

[0117] Furthermore, when the image reading device 100 reads a plurality of original documents 1, that is, when the light receiving unit 204 outputs a read signal Is for each of the plurality of original documents 1, it is preferable that the controller 300 heats the rod lens array 203 and the light guide 202 with the irradiation light Ls emitted from the light emitter 201 and the light guide 202 only once before the first read signal Is of the plurality of original documents 1 is output from the light receiving unit 204. It is also preferable that the correction unit 303 corrects shading in the read signal Is of the original document 1 output from the light receiving unit 204 when the rod lens array 203 and the light guide 202 are heated, using correction data 306 acquired when the rod lens array 203 and the light guide 202 are heated. This eliminates the need for the image reading device 100 to acquire correction data 306 each time the image reading device 1 reads a plurality of original documents 1, thereby reducing the time required to acquire the correction data 306. As a result, the image reading device 100 can suppress shading correction errors caused by temperature fluctuations of the image reading device 100 while increasing the productivity of reading a plurality of documents 1.

[0118] Furthermore, in order to output a read signal Is of the transported original document 1 from the light receiving unit 204, the controller 300 preferably starts emitting the irradiation light Ls from the light emitting unit 201 and the light guide 202 when the original document 1 is placed at a position where the transport of the original document 1 starts, for example, at the position of the original document placement unit A. This allows heating of the rod lens array 203 and the light guide 202 to start immediately after the original document 1 is placed at the original document placement unit A, thereby shortening the waiting time until the rod lens array 203 and the light guide 202 are deformed by heating. As a result, the image reading device 100 can suppress shading correction errors due to temperature fluctuations in the image reading device 100 while increasing the productivity of reading multiple original documents 1.

[0119] Furthermore, the controller 300 may change the timing at which the light emitting unit 201 starts emitting light depending on the distance d between the light emitting unit 201 and the light guide 202. The time it takes for the light guide 202 to deform due to heating varies depending on the distance d. For example, the shorter the distance d, the higher the heating efficiency and the faster the light guide 202 deforms, and the longer the distance d, the lower the heating efficiency and the slower the light guide 202 deforms. The distance d is determined depending on the arrangement of components in the image reading device 100. For example, when the distance d is 3 mm, the image reading device 100 sets the time from when the irradiation light Ls is emitted until the light receiving unit 204 outputs the read signal Is to 3 seconds.

[0120] The image reading device 100 varies the timing at which the light emitting unit 201 starts emitting light according to the distance d, and varies the time from when the irradiated light Ls is emitted until the light receiving unit 204 outputs the reading signal Is, thereby being able to start heating the light guide 202 at an appropriate timing according to the arrangement of components in the image reading device 100. As a result, the image reading device 100 can suppress shading correction errors due to temperature fluctuations in the image reading device 100.

[0121] [Second embodiment] An image reading device 100a according to the second embodiment will be described. Note that the same components as those in the first embodiment are given the same reference numerals, and redundant description will be omitted as appropriate.

[0122] 8 is a block diagram showing an example of the functional configuration of the controller 300a of the image reading device 100a. In this embodiment, the image reading device 100a includes a temperature sensor 400.

[0123] The temperature sensor 400 is an example of a temperature detection means that detects at least one of the temperature of the rod lens array 203 and the temperature around the rod lens array 203. There are no particular limitations on the temperature sensor 400 as long as it can output the detected temperature, and various temperature sensors such as a resistance thermometer or a radiation thermometer can be used.

[0124] The temperature sensor 400 may be located at any position within the image reading device 100a as long as it is capable of detecting at least one of the temperature of the rod lens array 203 and the temperature around the rod lens array 203.

[0125] The controller 300a has a temperature acquisition unit 308 that acquires a temperature detection signal Dt by inputting it, the temperature detection signal Dt being output from the temperature sensor 400. The controller 300a starts emitting irradiation light Ls from the light-emitting unit 201 and the light guide 202 when the temperature detected by the temperature sensor 400 reaches or exceeds a predetermined temperature before the read signals Is of the original 1 and the first read roller 19 are output from the light-receiving unit 204.

[0126] In the image reading device 100 according to the first embodiment, if the timing of irradiating the light Ls from the light-emitting unit 201 and the light guide 202 is determined based on time, shading correction errors may not be sufficiently suppressed. For example, if the ambient temperature of the image reading device 100 is lower than the temperature at the time the irradiation timing is determined, the temperatures of the light-emitting unit 201 and the light guide 202 may not rise sufficiently at the predetermined irradiation timing. As a result, a difference occurs in the deformation states of the rod lens array 203 and the light guide 202 between the time the correction data 306 is acquired and the time the document 1 is read, resulting in shading correction errors.

[0127] In this embodiment, the image reading device 100a starts emitting the irradiation light Ls based on the temperature detected by the temperature sensor 400, and therefore can emit the irradiation light Ls at a timing when the deformations of the rod lens array 203 and the light guide 202 reach saturation, regardless of the ambient temperature of the image reading device 100. This allows the image reading device 100a to suppress shading correction errors caused by temperature fluctuations of the image reading device 100a. Other effects are the same as those of the first embodiment.

[0128] [Third embodiment] Next, a description will be given of an image forming apparatus 500 according to a third embodiment. The image forming apparatus 500 has an image reading apparatus 100, and forms an image on a recording sheet as a recording medium based on an image read by the image reading apparatus 100.

[0129] Fig. 9 is a diagram showing an example of the configuration of the image forming apparatus 500. Fig. 9 is a front view showing the inside of the image forming apparatus 500 in a see-through manner.

[0130] 9, image forming apparatus 500 includes image reading apparatus 100, ADF 510 having a function as an image reading apparatus, paper feeding unit 502, and image forming unit 503. Note that image forming apparatus 500 may include image reading apparatus 100a instead of image reading apparatus 100.

[0131] The paper feed unit 502 has paper feed cassettes 521 and 522 that store recording paper of different sizes, and a paper feed means 523 consisting of various rollers that transport the recording paper stored in the paper feed cassettes 521 and 522 to the image forming position of the image forming unit 503.

[0132] The image forming section 503 includes an exposure device 531 , a photosensitive drum 532 , a developing device 533 , a transfer belt 534 , and a fixing device 535 .

[0133] The image forming unit 503 exposes a photosensitive drum 532 with an exposure device 531 based on the image of the document read by the image reading unit inside the ADF 510 to form a latent image on the photosensitive drum 532 .

[0134] Furthermore, image forming unit 503 develops the image by supplying different color toners to photosensitive drum 532 using developing device 533. Then, image forming unit 503 transfers the image developed on photosensitive drum 532 onto recording paper supplied from paper feed unit 502 using transfer belt 534, and then fixes the color image onto the recording paper by melting the toner of the toner image transferred onto the recording paper using fixing device 535.

[0135] By including the image reading device 100, the image forming device 500 can form a high-quality image on recording paper based on a read image in which shading correction errors due to temperature fluctuations of the image reading device 100 are suppressed. Note that other effects are similar to those of the image reading device 100 and the image reading device 100a.

[0136] Although one example of an embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications and improvements are possible within the scope of the present invention.

[0137] Each function of the embodiments can be realized by one or more processing circuits. Here, the term "processing circuit" in this specification includes a processor programmed to perform each function by software, such as a processor implemented by an electronic circuit, as well as devices such as an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and conventional circuit modules designed to perform each function described above. [Explanation of symbols]

[0138] 1 Manuscript 19 First reading roller (an example of a reference member) 20 First reading unit 25 Second reading unit 26 Second reading roller (an example of a reference member) 100 Image reader 201 Light-emitting unit (an example of a light-emitting means) 201a First light-emitting part 201b Second light-emitting part 202 Light guide body (an example of a second light guide member) 203 Rod lens array (an example of the first light guide member) 203a Rod Lens 204 Light receiving unit (an example of output means) 300 Controller (an example of a control means) 301 Irradiation timing control unit 302 Reading timing control unit 303 Correction unit (an example of correction means) 304 Storage Unit 305 Input / output section 306 Correction Data 307 Power Supply Control Unit 308 Temperature acquisition section 400 Temperature Sensor 500 Image forming device m Conveying direction n Width direction d distance Is reading signal IC reading signal Lr reflected light Ls Irradiation light (example of light) St irradiation control signal Sr Read control signal Pw power A. Document placement section B Separation feeding section C Resist section D Reversal section E First reading and conveying section F Second reading and transport section G Paper output section H Loading section [Prior art documents] [Patent documents]

[0139] [Patent Document 1] JP 2019-153867 A

Claims

1. An image reading device that outputs a read image of a document, an irradiation means for irradiating the document with light; a first light guiding member that guides the light irradiated from the irradiating means and reflected by the document; an output unit that outputs a read signal obtained from the reflected light guided by the first light guide member; a reference member for correcting shading in the read signal; a correction means for correcting the shading in the read signal of the document by using correction data obtained from the read signal of the reference member output from the output means, and outputting the read image; a control unit that controls the irradiation timing of the irradiation unit and the output timing of the output unit, the control means heats the first light guide member with the light irradiated from the irradiation means before the output means outputs the read signals of the original and the reference member, respectively; the correction unit corrects the shading in the read signal of the document output from the output unit in a state where the first light guiding member is heated, using the correction data obtained in the state where the first light guiding member is heated; The control unit heats the first light guide member until a deformation amount of the first light guide member due to heating reaches a saturation point.

2. the output means outputs the read signal for each of the plurality of originals; the control means heats the first light guide member with the light irradiated from the irradiation means only once before a first read signal among the read signals of the plurality of originals is output from the output means; 2. The image reading device according to claim 1, wherein the correction means corrects the shading in the reading signal of the document output from the output means when the first light guide member is heated, using the correction data acquired when the first light guide member is heated.

3. 3. The image reading device according to claim 1, wherein the control means starts irradiating the light from the irradiation means when the document is placed at a position where transportation of the document is to start, so that the reading signal of the document being transported is output from the output means.

4. a temperature detecting means for detecting at least one of a temperature of the first light guiding member and a temperature around the first light guiding member; 3. The image reading device according to claim 1, wherein the control means starts irradiating the light by the irradiation means when the temperature detected by the temperature detection means reaches or exceeds a predetermined temperature before the reading signals of the original and the reference member are output from the output means.

5. The irradiation means is Light emitting means; a second light guiding member that guides the light emitted from the light emitting means to the document; the control means heats the second light guide member with the light emitted by the light emitting means before the read signal of the document is output from the output means; 5. The image reading device according to claim 1, wherein the correction means uses the correction data obtained when the second light guide member is heated to correct the shading in the reading signal of the document output from the output means when the second light guide member is heated.

6. 6. The image reading device according to claim 5, wherein the control means changes the timing at which the light emitting means starts emitting the light in accordance with the distance between the light emitting means and the second light guiding member.

7. An image forming apparatus comprising the image reading device according to any one of claims 1 to 6.

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