JP6862816B2 - Image reader and image forming device - Google Patents

Description

The present invention relates to an image reading device and an image forming device.

Conventionally, in order to suppress a change in lens pitch due to the influence of heat, an image reader that performs shading correction for each scan of a document has been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2015-012517

However, in the prior art described in Patent Document 1, the output change rate of the rod lens array is calculated according to the elapsed time of continuous lighting of the light source unit in order to suppress the change in the lens pitch due to the influence of heat. Therefore, it is necessary to secure the calculation processing time of the output change rate of the rod lens array as a pre-process for shading correction, which may affect the improvement of scan productivity.

The present disclosure has been made in view of such a situation, and makes it possible to improve scan productivity while suppressing a change in lens pitch due to the influence of heat.

The image reading device according to the first aspect of the present disclosure includes an irradiation unit that irradiates light, a rod lens array that is arranged in the main scanning direction and collects the light emitted from the irradiation unit, and the rod lens array. An image reader that includes a light receiving element that converts the light collected by the data into an electric signal, and reads a document conveyed in the sub-scanning direction, and is a relative position between the rod lens array and the light receiving element. A correction data storage unit that stores correction data that associates relative position data that specifies a relationship with characteristic data related to the light receiving element, and a conversion unit that converts the electrical signal converted by the light receiving element into pixel values. And a scanning image processing unit that performs shading correction on the pixel value converted by the conversion unit based on the correction data stored in the correction data storage unit, and the correction data is preset. The characteristic data corresponding to the temperature is associated with the reading image processing unit, and when the shading correction is performed, the correction is based on the amount of heat generated by the irradiation unit and the relative position data. The correction data stored in the data storage unit is used.

When performing shading correction, the image reader uses the correction data based on the amount of heat generated in the irradiation unit and the relative position data. Therefore, when the correction data is used, the characteristic data related to the light receiving element related to the relative position data is used for the change in the lens pitch due to the influence of heat. Since the correction data is associated with the characteristic data corresponding to the preset temperature, the shading correction can be performed without calculating the output change rate of the rod lens array due to the influence of heat. Therefore, it is possible to improve the scan productivity while suppressing the change in the lens pitch due to the influence of heat.

Further, a plurality of the light receiving elements are arranged at a constant pitch for each block along the main scanning direction, and the blocks are a group of a plurality of the light receiving elements at positions deviated from each other along the sub scanning direction. The relative position data is specified by the position rank data ranked according to the amount of deviation of the light receiving element from the optical axis of the rod lens array. It is preferable that the scanned image processing unit selects whether or not to use the correction data for the shading correction based on the position rank data.

Further, the position rank data is ranked higher as the deviation amount becomes smaller, and the scanned image processing unit exceeds the reference rank in which the ranking of the position rank data is preset. In this case, it is preferable to select to use the correction data for the shading correction.

Further, the scanned image processing unit selects whether or not to use the correction data for the shading correction for each of the blocks, and the plurality of light receiving elements included in the same block are located at the positions. It is preferable that the rank data are the same.

Further, it is preferable that the amount of heat generated in the irradiation unit is obtained based on the irradiation duration of the irradiation unit.

Further, it is preferable that the characteristic data includes initial characteristic data related to the light receiving element and white correction data and black correction data based on the irradiation duration of the irradiation unit.

Further, a density reference member that faces the rod lens array and reflects at least a part of the light emitted from the irradiation unit to the rod lens array, and a density reference member that reflects the document each time the document is conveyed. The average value processing unit for obtaining the average value of the pixel values obtained by converting at least a part of the light to be generated into the pixel values by the conversion unit and the average value of the pixel values obtained by the average value processing unit are stored. Further including an average value storage unit, the average value processing unit obtains an average value of the pixel values along the sub-scanning direction, and the average value of the pixel values is used for transporting the document. Therefore, the pixel values converted by the conversion unit are averaged and obtained at regular transport times, and the reading image processing unit determines that the ranking of the position rank data does not exceed the reference rank. It is preferable to select to use the average value of the pixel values stored in the average value storage unit for the shading correction.

Further, the image forming apparatus according to the second aspect of the present disclosure includes the image reading apparatus described above, and similarly to the case of the image reading apparatus, it suppresses the change in the lens pitch due to the influence of heat. At the same time, scanning productivity can be improved.

According to the first and second aspects of the present disclosure, it is possible to improve the scan productivity while suppressing the change in the lens pitch due to the influence of heat.

It is a figure which shows the whole structure example of the image forming apparatus 1 to which this disclosure is applied. It is a figure which shows the structural example of the close contact type image sensor 14. It is a figure which shows the example of the optical characteristic of the rod lens array 144. It is a figure which shows the arrangement example of the chip which includes a plurality of light receiving elements 142a. It is a figure which shows an example of the positional relationship between the optical axis of the rod lens array 144, and the light receiving element 142a. It is a figure which shows an example of the fixed part such as a substrate 142b and a rod lens array 144. It is a figure which shows an example of the linear expansion coefficient of a substrate 142b, a rod lens array 144 and the like. It is a figure which shows the phase change example of the rod lens array 144 by thermal expansion. It is a figure which shows an example of the correlation between the main scanning position and an output level by thermal expansion. It is a figure which shows an example of the periodic noise of a rod lens array 144. It is a figure which shows the example of the data structure stored in the correction data storage part 147. It is a functional block diagram of an image reading device 10.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the following embodiments.

FIG. 1 is a diagram showing an overall configuration example of the image forming apparatus 1 to which the present disclosure is applied. As shown in FIG. 1, the image forming apparatus 1 includes an image reading apparatus 10, a paper feeding unit 20, and an image forming unit 30. The paper feed unit 20 includes a paper feed cassette 21 and a paper feed transport unit 22. The paper feed cassette 21 stores recording papers having different paper sizes. The paper feed transport unit 22 includes various rollers and transports the recording paper stored in the paper feed cassette 21 to the image forming position of the image forming unit 30. The image forming unit 30 includes an exposure device 31, a photosensitive drum 32, a developing device 33, a transfer belt 34, and a fixing device 35. The image forming unit 30 supplies the photosensitive drum 32 with toners of different colors by the exposure device 31 based on the image data of the document d read by the image reading device 10 to develop the image. The image forming unit 30 transfers the toner image developed on the photosensitive drum 32 by the transfer belt 34 to the recording paper supplied from the paper feeding unit 20. The image forming unit 30 melts the toner of the toner image transferred to the recording paper by the fixing device 35, so that the color image is fixed on the recording paper.

The image reading device 10 includes an ADF 10a and an image reading unit 10b. The ADF 10a includes a document tray 11, a paper output tray 12, a paper passing path 13, a close contact image sensor 14, a density reference member 15, and the like. The concentration reference member 15 is used when correcting the shading of the ADF 10a. The image reading unit 10b includes a document illumination unit 42, a reflection mirror 43, a condenser lens 44, a line image sensor 45, a platen glass 46, and the like. The image reading device 10 separates the documents d set in the document tray 11 one by one, feeds them out, and conveys the documents d set in the document tray 11 in the sub-scanning direction along the paper passing path 13 in which the close contact type image sensor 14 is arranged. Paper is ejected to the output tray 12. The document illumination unit 42 includes a lamp 42a and a mirror 42b. While the document d is conveyed in the sub-scanning direction along the paper passing path 13, the line-by-line reading operation in the main scanning direction is repeated by the document illumination unit 42, the reflection mirror 43, the condenser lens 44, and the line image sensor 45. Will be executed. A white reference plate 41 is attached so as to face the image reading unit 10b in close proximity to each other. The white reference plate 41 is used at the time of shading correction of the image reading unit 10b. The lamp 42a is turned on in a state where the document d does not exist between the image reading unit 10b and the white reference plate 41, and the light is applied to the white reference plate 41. The light including the reflected light of the white reference plate 41 is received by the line image sensor 45 via the mirror 42b, the reflecting mirror 43, and the condenser lens 44.

FIG. 2 is a diagram showing a configuration example of the close contact type image sensor 14. As shown in FIG. 2, the close contact type image sensor 14 includes a glass 141, a sensor module 142, a rod lens array 144, irradiation units 145a, 145b, an aluminum frame 146, and the like. The glass 141 is provided on the reading surface side of the close contact type image sensor 14. The irradiation units 145a and 145b irradiate light. Specifically, the irradiation units 145a and 145b irradiate uniform light in the main scanning direction. A rod lens array 144 is provided between the irradiation unit 145a and the irradiation unit 145b. In the rod lens array 144, cylindrical lenses are arranged in the main scanning direction, and the light emitted from the irradiation units 145a and 145b is collected. Specifically, the rod lens array 144 is integrally formed by sealing a large number of cylindrical lenses with a flexible plastic material. The main scanning direction is a direction perpendicular to the direction in which the document d moves on the transport path. On the other hand, the sub-scanning direction is the direction in which the document d moves. When the irradiation units 145a and 145b are collectively referred to, they are referred to as the irradiation unit 145. Specifically, the irradiation unit 145 includes an LED, a light guide body, a holding member, and the like.

One end of the rod lens array 144 faces the glass 141, and the other end of the rod lens array 144 faces the sensor module 142. The sensor module 142 includes a light receiving element 142a, a substrate 142b, and the like. The light receiving element 142a converts the light collected by the rod lens array 144 into an electric signal. Specifically, the light receiving element 142a reads the magnitude of the amount of light collected by the rod lens array 144 as an optical signal at a preset cycle. The light receiving element 142a converts an optical signal into an electric signal, accumulates the electric charge forming the converted electric signal for a preset time, and then outputs the light signal. The substrate 142b includes a drive circuit for the light receiving element 142a and the like.

The concentration reference member 15 is a plate-shaped member facing the glass 141. The result of the close contact type image sensor 14 reading the density reference member 15 is used as a reference at the time of shading correction. When the density reference member 15 is white, it is used as a white reference in a state where light is irradiated by the irradiation unit 145 at the time of shading correction. When the close contact type image sensor 14 reads the document d conveyed in the sub-scanning direction, the density reference member 15 is used as a guide plate. The density reference member 15 is used as a black reference in a state where light is not irradiated by the irradiation unit 145 during shading correction.

FIG. 3 is a diagram showing an example of optical characteristics of the rod lens array 144. FIG. 4 is a diagram showing an arrangement example of a chip including a plurality of light receiving elements 142a. FIG. 5 is a diagram showing an example of the positional relationship between the optical axis of the rod lens array 144 and the light receiving element 142a. As shown in FIG. 3, the optical position where the pitch unevenness period of the rod lens array 144 is most apparent is the center position of the rod lens array 144. Therefore, the sensor module 142 arranged at a position deviated from the center position of the rod lens array 144 in the front-rear direction along the sub-scanning direction tends to reduce the waviness of the pitch unevenness cycle. Therefore, based on the sub-scanning position information for each sensor module 142, the correction priority processing of pitch unevenness due to the influence of heat is ordered, and further, the shading correction is performed in consideration of the influence of heat, for example, the lighting duration of the irradiation unit 145. Therefore, it is possible to suppress the influence of heat on the lens pitch and shorten the calculation processing time.

Therefore, the sub-scanning position of the sensor module 142, that is, the correction data for associating the relative position data for specifying the relative positional relationship between the rod lens array 144 and the light receiving element 142a and the characteristic data related to the light receiving element 142a is used. The shading correction to be performed will be described. As shown in FIG. 3, a plurality of light receiving elements 142a are arranged at a constant pitch for each block along the main scanning direction. The block is an aggregate as a sensor module 142 in which a plurality of light receiving elements 142a are arranged as a group at positions deviated from each other along the sub-scanning direction. That is, as shown in FIG. 4, the close contact type image sensor 14 is composed of a plurality of chips (1) to (9) as one chip for each predetermined number of light receiving elements 142a. Based on the physical constraints of Chips (1) to (9), Chips (1) to (9) are arranged with a slight positional deviation in the main scanning direction and the sub-scanning direction. Therefore, as shown in FIG. 5, it is not possible to linearly arrange all Chips (1) to (9) on the optical axis of the rod lens array 144. As a result, the sensor module 142 can be classified into a chip arrangement on the optical axis of the rod lens array 144 having superior optical characteristics and a chip arrangement in which the influence of the pitch unevenness period of the rod lens array 144 is slight. The chip arrangement on the optical axis of the rod lens array 144 having superior optical characteristics is the chip position where the pitch unevenness period of the rod lens array 144 becomes remarkable.

Considering the above chip arrangement, the relative position data can be specified by the position rank data ranked according to the amount of deviation of the light receiving element 142a from the optical axis of the rod lens array 144. Specifically, assuming that the position rank data is ranked higher as the amount of deviation of the light receiving element 142a from the optical axis of the rod lens array 144 becomes smaller, the reference rank is set in advance. It can be the chip information that should consider the influence of thermal expansion based on whether or not it exceeds. The position rank data of the plurality of light receiving elements 142a included in the same block are the same.

Next, a phenomenon in which the pitch unevenness period of the rod lens array 144 changes due to thermal expansion will be described. FIG. 6 is a diagram showing an example of fixed locations such as the substrate 142b and the rod lens array 144. FIG. 7 is a diagram showing an example of the coefficient of linear expansion of the substrate 142b and the rod lens array 144 and the like. FIG. 8 is a diagram showing an example of a phase change of the rod lens array 144 due to thermal expansion. FIG. 9 is a diagram showing an example of the correlation between the main scanning position due to thermal expansion and the output level. FIG. 10 is a diagram showing an example of periodic noise of the rod lens array 144.

In one example of FIG. 6, a structure is shown in which the central portion of the substrate 142b and the central portion of the aluminum frame 146 are fixed by the fixing member 61 to cause a thermal expansion transition in the main scanning direction. That is, it is a structure that causes thermal expansion transition in the direction of the first pixel and the direction of the rear end pixel. The fixing member 61 may be a method of reference-fixing a member such as a screw or a fixing shaft, or a member formed of sheet metal or the like with, for example, a UV curable adhesive. An adhesive layer 62 is formed between the aluminum frame 146 and the rod lens array 144. As shown in FIG. 7, the rod lens constituting the rod lens array 144, the substrate 142b, and aluminum, which is the material of the aluminum frame 146, have different coefficients of linear expansion, and therefore have different lengths of thermal expansion. .. Therefore, as shown in FIG. 8, the peak position shifts depending on the temperature. Further, as shown in FIG. 9, as the distance from the fixed position increases, the influence of thermal expansion is strongly affected. In one example of FIG. 9, one chip is composed of Chips (1) to (24), and Chips (12) and (13) near the center are fixed. Therefore, if the rod lens array 144 has a waviness in the pitch unevenness cycle, the reading result of the close contact type image sensor 14 includes the periodic noise of vertical streaks as shown in FIG. On the other hand, if the undulation of the pitch unevenness cycle of the rod lens array 144 does not occur, as shown in FIG. 10, the reading result of the close contact type image sensor 14 does not include the periodic noise of the vertical streaks. Further, since the peak position becomes larger depending on the material and the mounting position of the fixing member 61, specifically, it may change at the level of several pixels.

As the irradiation duration of the irradiation unit 145 becomes longer, the amount of heat generated by the irradiation unit 145 increases and the substrate 142b and the like are affected by thermal expansion. Therefore, the correction data of the shading correction is the irradiation unit 145. It is preferable that the irradiation duration depends on the temperature. Specifically, the correction data may be associated with characteristic data corresponding to each of a plurality of preset temperatures. FIG. 11 is a diagram showing an example of data configuration stored in the correction data storage unit 147. As shown in FIG. 11, the correction data is associated with the position rank data and the characteristic data for each chip, and the characteristic data is associated with N1, N2, and N3 for each preset temperature. .. The characteristic data for each of N1, N2, and N3 may correspond to, for example, those at 0 ° C, 25 ° C, and 50 ° C. The position rank data is associated with the relative position data.

FIG. 12 is a functional block diagram of the image reading device 10. The image control unit 201 is composed of a ROM, a RAM, a CPU, and the like, and controls the close contact type image sensor 14 and the read image processing unit 212. The close contact type image sensor 14 includes a correction data storage unit 147. The correction data storage unit 147 stores correction data as shown in FIG. From the above description, the correction data associates the relative position data with the characteristic data related to the light receiving element 142a. The conversion unit 211 converts the electric signal converted by the light receiving element 142a into a pixel value. The scanned image processing unit 212 performs shading correction on the pixel values converted by the conversion unit 211 based on the correction data stored in the correction data storage unit 147. When performing shading correction, the scanned image processing unit 212 uses the correction data stored in the correction data storage unit 147 based on the amount of heat generated by the irradiation unit 145 and the relative position data.

Specifically, the scanned image processing unit 212 selects whether or not to use the correction data for the shading correction based on the position rank data. When the position rank data exceeds the reference rank, the scanned image processing unit 212 selects to use the correction data for the shading correction. The reference rank may be set to a threshold value at which the swell of the pitch unevenness cycle becomes large. For example, the case where the position rank data is 3 may be used as the reference rank. The scanned image processing unit 212 selects whether or not to use the correction data for the shading correction for each block. One block corresponds to one chip, and the light receiving elements 142a included in one chip have the same position rank data. Therefore, in the case of each block, those having the same pitch unevenness cycle swell are targeted. Although not shown, the characteristic data includes initial characteristic data related to the light receiving element 142a, and white correction data and black correction data based on the irradiation duration of the irradiation unit 145. The initial characteristic data related to the light receiving element 142a is data in a state not affected by heat, and is characteristic data based on the specifications of the light receiving element 142a. That is, the initial characteristic data is characteristic data related to the light receiving element 142a in an environment that is not affected by temperature. On the other hand, the white correction data is data for correcting the density on the white side corresponding to each of a plurality of preset temperatures. Further, the black correction data is data for correcting the density on the black side corresponding to each of a plurality of preset temperatures.

The scanned image processing unit 212 is composed of a ROM, RAM, CPU, etc., and has functions such as a white correction processing unit 212a, a black correction processing unit 212b, an average value processing unit 212c, a correction value switching unit 212f, and a reading correction processing unit 212g. The program that realizes is executed. That is, the functions of the average value processing unit 212c, the correction value switching unit 212f, the reading correction processing unit 212g, and the like are realized by the program module. The average value storage unit 212d and the transfer data storage unit 212e may be realized by a semiconductor memory such as a flash memory. The average value processing unit 212c executes an instruction to obtain an average value of pixel values in which at least a part of the light reflected from the density reference member 15 is converted into pixel values by the conversion unit 211 each time the document d is conveyed. .. The concentration reference member 15 has been outlined above. Specifically, the rod lens faces at least a part of the light emitted from the irradiation unit 145 and faces the rod lens array 144 via the glass 141. It reflects off the array 144. The average value storage unit 212d stores the average value of the pixel values obtained by the average value processing unit 212c.

Specifically, the average value processing unit 212c executes an instruction to obtain the average value of the pixel values along the sub-scanning direction. The average value of the pixel values is obtained by averaging the pixel values converted by the conversion unit 211 at regular transport times as the document d is transported. The correction value switching unit 212f is instructed to select to use the average value of the pixel values stored in the average value storage unit 212d in order to perform shading correction when the ranking of the position rank data does not exceed the reference rank. To execute. On the other hand, when the ranking of the position rank data exceeds the reference rank, the correction value switching unit 212f is transferred from the correction data storage unit 147 to the transfer data storage unit 212e in order to perform shading correction as described above. Perform instructions to choose to use the correction data. The reading correction processing unit 212g executes an instruction to perform shading correction based on the selection result of the correction value switching unit 212f. Although details are omitted, the average value processing unit 212c uses the white correction data processed by the white correction processing unit 212a and the black correction data processed by the black correction processing unit 212b as input data. The white correction processing unit 212a executes an instruction to perform white shading correction for correcting the density on the white side. The black correction processing unit 212b executes an instruction to perform black shading correction for correcting the density on the black side. The average value processing unit 212c does not have to use both the white correction data and the black correction data. For example, the average value processing unit 212c may execute an instruction to obtain an average value for either the white correction data or the black correction data. In any case, if the shading correction is performed, the unevenness of the density level of the image is corrected so that the entire image based on the electric signal read by the close contact type image sensor 14 has an average uniform brightness. Will be done.

In other words, one or more programs executed by the image reader 10 are relative to the instruction to use the correction data based on the amount of heat generated by the irradiation unit 145 and the relative position data when performing shading correction. Based on the position rank data associated with the position data, the shading correction includes an instruction to select to use either the correction data or the average value of the pixel values.

From the above description, in the present disclosure, when performing shading correction, the image reading device 10 uses the correction data based on the amount of heat generated in the irradiation unit 145 and the relative position data. Therefore, when the correction data is used, the characteristic data related to the light receiving element 142a associated with the relative position data is used for the change in the lens pitch due to the influence of heat. Since the correction data is associated with characteristic data corresponding to each of a plurality of preset temperatures, a correction value that compensates for the influence of heat, such as the output change rate of the rod lens array 144 due to the influence of heat. Shading correction can be performed without calculating. Therefore, it is possible to improve the scan productivity while suppressing the change in the lens pitch due to the influence of heat.

Further, in the present disclosure, the image reading device 10 selects whether or not to use the correction data for the shading correction based on the position rank data. The position rank data is such that the relative position data is ranked according to the amount of deviation of the light receiving element 142a from the optical axis of the rod lens array 144. If the light receiving element 142a is deviated from the optical axis of the rod lens array 144, the waviness of the pitch unevenness cycle tends to be reduced, so that the lens pitch is not easily changed by the influence of heat. On the other hand, if the light receiving element 142a is close to the optical axis of the rod lens array 144, the waviness of the pitch unevenness cycle tends to be strong, so that the range pitch is easily changed by the influence of heat. That is, the optical position where the pitch unevenness period of the rod lens array 144 becomes most apparent is on the optical axis of the rod lens array 144, that is, the center position of the rod lens array 144. Therefore, by using the position rank data, it is possible to appropriately select the light receiving element 142a that is susceptible to the change in the range pitch due to the influence of heat. Therefore, the chip composed of a block unit including a plurality of light receiving elements 142a can be selected. Among them, the chip that changes due to thermal expansion can be grasped in advance.

Further, in the present disclosure, the image reading device 10 selects to use the correction data for shading correction when the ranking of the position rank data exceeds the preset reference rank. The position rank data is ranked higher as the amount of deviation of the light receiving element 142a from the optical axis of the rod lens array 144 becomes smaller. Therefore, the image reading device 10 does not require time-consuming arithmetic processing such as a shift in phase change due to heat, and can select the use of correction data for shading correction, thus shortening the entire shading correction processing time. Can be made to.

Further, in the present disclosure, the image reading device 10 selects whether or not to use correction data for shading correction for each block including a plurality of light receiving elements 142a. The plurality of light receiving elements 142a included in the same block have the same position rank data. Therefore, since the use of correction data is selected for each block in which waviness of the same pitch unevenness cycle occurs, shading correction suitable for the mounting environment of the light receiving element 142a can be performed.

Further, in the present disclosure, the image reading device 10 determines the amount of heat generated in the irradiation unit 145 based on the irradiation duration of the irradiation unit 145. The amount of heat generated by the irradiation unit 145 is due to the light source of the irradiation unit 145. The light source of the irradiation unit 145 is a heat source that is a main factor of thermal expansion. Since the irradiation unit 145 applies heat to the surroundings by continuously lighting the light source during scan control, the substrate 142b, the rod lens array 144, and the like thermally expand as the irradiation duration of the irradiation unit 145 becomes longer. The pitch unevenness period of the rod lens array 144 changes due to thermal expansion of the substrate 142b and the rod lens array 144 and the like. The irradiation duration of the irradiation unit 145 corresponds to the elapsed lighting time of the light source. That is, the irradiation duration of the irradiation unit 145 corresponds to the elapsed lighting time of the light source during scan control, and the amount of heat generated by the irradiation unit 145 corresponds to the heat source that is the main factor of thermal expansion. Therefore, by grasping the elapsed lighting time of the light source during scan control, it is possible to predict in advance the change in the relative positional relationship between the rod lens array 144 and the light receiving element 142a due to thermal expansion.

Further, in the present disclosure, the characteristic data related to the light receiving element 142a includes the initial characteristic data related to the light receiving element 142a and the white correction data and the black correction data based on the irradiation duration of the irradiation unit 145. As the irradiation duration of the irradiation unit 145 increases, the amount of heat generated by the irradiation unit 145 increases, so that a large amount of heat is given to the rod lens array 144, the substrate 142b supporting the light receiving element 142a, and the like, and the rod lens array 144 The relative positional relationship between the rod lens array 144 and the light receiving element 142a changes due to thermal expansion of the substrate 142b or the like that supports the light receiving element 142a. For example, if the light receiving element 142a changes, the positional relationship between the rod lens array 144 and the light receiving element 142a changes. Therefore, if the white correction data and the black correction data are based on the irradiation duration of the irradiation unit 145, each pixel data corresponding to the elapsed lighting time of the light source can be prepared, so that shading correction in consideration of thermal expansion is simplified. Moreover, it can be realized in a short time.

Further, in the present disclosure, the image reading device 10 obtains an average value of pixel values corresponding to at least a part of the light reflected from the density reference member 15. The average value of the pixel values is obtained by averaging the pixel values converted by the conversion unit 211 at regular transport times as the document d is transported. The condition for selecting the use of the average value of the pixel values instead of the correction data for shading correction is that the ranking of the position rank data does not exceed the preset reference rank. In this case, the light receiving element 142a corresponds to one that is deviated from the optical axis of the rod lens array 144. Therefore, since the waviness of the pitch unevenness cycle tends to be reduced, the change in the lens pitch due to the influence of heat is unlikely to occur. Therefore, the fact that the average value of the pixel values is selected for shading correction means that the light receiving element 142a related to the pixel value subject to shading correction is less susceptible to changes in the lens pitch due to the influence of heat. Means that it is below. In such an environment, since it is not necessary to perform a process of compensating for a change in the lens pitch due to the influence of heat, it is not necessary to perform an operation considering the phase shift due to the influence of heat at the time of shading correction. Therefore, it is possible to correct unevenness in the amount of light and unevenness in the sensitivity of the light receiving element 142a that may occur when reading the document d without requiring a lot of time for shading correction. Therefore, the image reading device 10 can stabilize the reading image quality of the image formed on the document d regardless of the presence or absence of the influence of heat.

Although the image forming apparatus 1 which is one aspect of the present disclosure has been described above based on the embodiment, the present disclosure is not limited to this, and changes may be made without departing from the gist of the present disclosure. Good.

For example, FIG. 2 has described an example in which the concentration reference member 15 in the present embodiment has a plate shape, but the present invention is not particularly limited to this. For example, the concentration reference member 15 may have a roller shape. That is, the density reference member 15 may have a structure that can reflect at least a part of the light emitted from the irradiation unit 145 to the rod lens array 144 and can be used as a transport guide for the document d.

Further, as a data configuration example stored in the correction data storage unit 147 in the present embodiment, an example in which the correction data includes characteristic data corresponding to a plurality of temperatures for each chip has been described, but the correction data is particularly limited to this. It's not something. For example, a lens with a low ranking is less susceptible to changes in the lens pitch due to the influence of heat, so the temperature pattern may be reduced as compared with a lens with a high ranking. Further, those having a high ranking are susceptible to changes in the lens pitch due to the influence of heat, and therefore include three temperature patterns, but four or more temperature patterns may be included. Further, the position rank data is arranged so that the ranking becomes higher as the amount of deviation of the light receiving element 142a from the optical axis of the rod lens array 144 becomes smaller, but the reverse is also possible. That is, the position rank data is such that the ranking becomes lower as the amount of deviation of the light receiving element 142a from the optical axis of the rod lens array 144 becomes smaller, and the priority that the correction data is used for the lower ranking data. Should be set high. That is, as long as the relative positional relationship between the rod lens array 144 and the light receiving element 142a is close, it is sufficient that the correction data is selected.

Further, an example in which the functions of the average value processing unit 212c, the correction value switching unit 212f, the reading correction processing unit 212g, and the like in the present embodiment are realized by the program module has been described, but the present invention is not particularly limited thereto. For example, these functions may be realized as hardware by a random logic circuit.

Further, although an example in which the amount of heat generated in the irradiation unit 145 in the present embodiment is obtained based on the irradiation duration of the irradiation unit 145 has been described, the amount of heat is not particularly limited to this. For example, it may be a parameter that can estimate the temperature, such as the number of sheets of the document d that has passed through the close contact type image sensor 14.

The timing for switching the correction data for each temperature may be determined based on the number of sheets of the document d read by the close contact image sensor 14. For example, if a setting table in which the correlation between the number of sheets of the document d read by the close contact type image sensor 14 and the internal temperature of the close contact type image sensor 14 is set is created based on simulation or actual measurement, the setting table is used. The timing of switching the correction data for each temperature can be controlled.

1 image forming device, 10 image reading device, 10a ADF, 10b image reading unit,
11 manuscript tray, 12 paper output tray, 13 paper passage,
14 Adhesive image sensor, 141 glass, 142 sensor module,
142a light receiving element, 142b substrate, 144 rod lens array,
145, 145a, 145b Irradiation section, 146 aluminum frame,
147 correction data storage unit, 15 concentration reference member,
20 paper feed unit, 21 paper feed cassette, 22 paper feed transport unit,
30 image forming unit, 31 exposure device, 32 photosensitive drum, 33 developing device,
34 Transfer belt, 35 Fixing device, 41 White reference plate, 42 Original lighting section,
42a lamp, 42b mirror, 43 reflective mirror, 44 condenser lens,
45 line image sensor, 46 platen glass,
61 fixing member, 62 adhesive layer, 201 image control unit, 211 conversion unit,
212 scanned image processing unit, 212a white correction processing unit, 212b black correction processing unit,
212c average value processing unit, 212d average value storage unit, 212e transfer data storage unit,
212f correction value switching unit, 212g reading correction processing unit, d original

Claims (7)

The irradiation part that irradiates light and
A rod lens array that is arranged in the main scanning direction and collects the light emitted from the irradiation unit,
A light receiving element that converts the light collected by the rod lens array into an electric signal, and
An image reader that reads a document conveyed in the sub-scanning direction.
A correction data storage unit that stores correction data that associates relative position data that specifies the relative positional relationship between the rod lens array and the light receiving element with characteristic data related to the light receiving element.
A conversion unit that converts the electric signal converted by the light receiving element into a pixel value, and
A scanning image processing unit that performs shading correction on the pixel value converted by the conversion unit based on the correction data stored in the correction data storage unit.
With
The correction data is
The characteristic data corresponding to the preset temperature is associated with the data.
The scanned image processing unit
When performing the shading correction, the correction data stored in the correction data storage unit is used based on the amount of heat generated in the irradiation unit and the relative position data.
The light receiving element is
A plurality of blocks are arranged at a constant pitch along the main scanning direction.
The block is
An aggregate in which a plurality of the light receiving elements are arranged as a group at positions deviated from each other along the sub-scanning direction.
The relative position data is
It is specified by the position rank data ranked according to the amount of deviation of the light receiving element from the optical axis of the rod lens array.
The scanned image processing unit
Select whether or not to use the correction data for the shading correction based on the position rank data.
Image reader. The position rank data is
As the amount of deviation becomes smaller, the ranking becomes higher.
The scanned image processing unit
If the ranking of the position rank data exceeds a preset reference rank, the correction data is selected to be used for the shading correction.
The image reading device according to claim 1. The scanned image processing unit
For each block, it is selected whether or not to use the correction data for the shading correction.
The plurality of light receiving elements included in the same block may be
The position rank data are the same,
The image reading device according to claim 1 or 2. The amount of heat generated in the irradiation part is
It is obtained based on the irradiation duration of the irradiation unit.
The image reading device according to any one of claims 1 to 3. The characteristic data is
The initial characteristic data related to the light receiving element and the white correction data and the black correction data based on the irradiation duration of the irradiation unit are included.
The image reading device according to claim 4. A concentration reference member that faces the rod lens array and reflects at least a part of the light emitted from the irradiation unit to the rod lens array.
Each time the document is conveyed, at least a part of the light reflected from the density reference member is converted into the pixel value by the conversion unit.
An average value storage unit that stores the average value of the pixel values obtained by the average value processing unit, and an average value storage unit.
With more
The average value processing unit
The average value of the pixel values is obtained along the sub-scanning direction.
The average value of the pixel values is
The pixel values converted by the conversion unit are averaged and obtained at regular transfer times as the document is conveyed.
The scanned image processing unit
When the ranking of the position rank data does not exceed the reference rank, it is selected to use the average value of the pixel values stored in the average value storage unit for the shading correction.
The image reading device according to claim 2. An image forming apparatus including the image reading apparatus according to any one of claims 1 to 6.

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