Patent Application
20240255865
The present application claims priority from Japanese Applications JP2023-012365, JP2023-012366, and JP2023-012367 the content of which is hereby incorporated by reference into this application.
The present disclosure relates to an image-forming apparatus and the like.
An electrophotographic image-forming apparatus is known in which a light beam emitted from a light source, such as a laser diode, is focused on a photoconductor drum (image carrier) by a scanning optical system to form an electrostatic latent image on a surface of the photoconductor drum.
In this type of image-forming apparatus, a phenomenon of reciprocity failure occurs in which, even when a total amount of light applied to the photoconductor drum is the same, a latent image formation state differs depending on the relationship between an amount of light and an exposure time. Specifically, in a case of exposure for a very short period of time, as compared with a case of exposure over a relatively long period of time, an amount of change in potential of a photoreceptor is reduced in spite of the same total exposure amount, and thus the reciprocity failure occurs. When this is applied to a multi-beam scanning optical system, the reciprocity failure appears as image density unevenness.
In general, in order to cope with the image density unevenness caused by the reciprocity failure, a method is known in which a vertical cavity surface emitting laser (VCSEL) in which a large number of light emitting points are arranged in a main scanning direction and a sub-scanning direction is used as a light source, and multiple exposure is performed at a certain scanning frequency or more to make density differences invisible. However, in the related art, the number of beams, such as 32 beams, is enormous, and a driving system is complicated. Furthermore, there arises a problem in that cost is largely increased.
In another related art, in order to cope with the density unevenness caused by the reciprocity failure, an image-forming apparatus has been proposed in which an amount of toner to be developed on superposed lines of an m-th main scanning operation and an (m+1)-th main scanning operation is calculated and a first light amount of the (m+1)-th scanning operation and an N-th light amount of the m-th scanning operation are adjusted to reduce an adverse effect of the reciprocity failure. However, the following problems arise.
In the related art, when electronic bow correction is performed, synchronization between density correction and bow correction cannot be easily realized due to influence of partial magnification correction of the density correction and the bow correction and the asynchronism of a density correction circuit, and a streak image is likely to be generated at a boundary of the bow correction. In addition, highly accurate density correction in consideration of various variations cannot be easily realized, and a density level difference is likely to occur at the boundary of the bow correction.
Furthermore, as another technique, an image-forming apparatus is known which corrects an image writing position by forming a registration mark and detecting a deviation amount with respect to a normal position in order to suppress color misregistration based on various causes in image formation, but this technique does not mean the bow correction itself.
In general, in a case where a multi-beam scanning optical system is used, when electronic bow correction is performed, density unevenness occurs due to reciprocity failure caused by surface-crossing by an end semiconductor laser device (LD).
As a further technique, an operation exposure method is known in which, in scanning exposure, when exposure by an m-th light beam in light beams for performing an N-th main scanning operation and exposure by a first light beam in light beams for performing an (N+1)-th main scanning operation overlap each other, power of at least one of the first light beam and the m-th light beam is changed (N is an integer on one side).
As a still further technique, in an optical scanning device that performs multi-exposure, an exposure unit is controlled such that a difference between an exposure amount of a first exposure and an exposure amount of a second exposure performed based on image data when a type of an image is determined to be a character is larger than a difference between an exposure amount of a first exposure and an exposure amount of a second exposure performed based on image data when a type of an image is determined to be a picture by a determiner.
However, in the related arts, when the electronic bow correction is performed using the scanning optical system of the multi-beam, a countermeasure against the surface-crossing reciprocity failure due to the end LD is insufficient, and the density unevenness occurs.
An object of the present disclosure is to provide an image-forming apparatus and the like capable of suppressing generation of a density level difference caused by influence of reciprocity failure when electronic density correction and bow correction are performed.
According to an aspect of the present disclosure, an image-forming apparatus employing an electrophotographic method scans a surface of an image carrier with multi-beams emitted from a plurality of light emitting elements based on image data. The image-forming apparatus includes at least one bow corrector that performs electronic bow correction on the image data, at least one density smoothing processor that performs a density smoothing process to smooth a density level difference of an image subjected to the bow correction, at least one density correction processor that performs density correction on the image subjected to the bow correction by light amount correction of a surface-crossing exposure segment, and at least one of a light emitting element driver controller that controls light emission of a plurality of light emitting elements of a light beam emitter based on the image data subjected to the density smoothing process and a control signal subjected to the density correction.
According to another aspect of the present disclosure, a method for controlling an image-forming apparatus that scans a surface of an image carrier with light beams emitted from a plurality of light emitting elements based on image data includes performing electronic bow correction on the image data, performing a density smoothing process to smooth a density level difference of an image subjected to the bow correction, performing density correction on the image subjected to the bow correction by light amount correction of a surface-crossing exposure segment, and controlling light emission of a plurality of light emitting elements of a light beam emitter based on the image data subjected to the density smoothing process and a control signal subjected to the density correction.
According to a further aspect of the present disclosure, the image-forming apparatus can suppress a density level difference by performing the density smoothing process and the density correction on image data so that the density level difference does not occur in a halftone image due to influence of the reciprocity failure even when the electronic bow correction is performed.
Embodiments of the present disclosure will be described hereinafter with reference to the accompanying drawings.
Note that the embodiments below are merely examples for describing the present disclosure, and the technical scope of the disclosure set forth in the claims is not limited to the description below.
First, a configuration of an image-forming apparatus 10 according to a first embodiment will be described.
As illustrated in
As illustrated in a diagram of a control system in
As illustrated in
Moreover, the at least one controller 100 realizes various functions by reading and executing various programs, and includes, for example, one or more arithmetic devices (for example, a central processing unit (CPU)).
The image inputter 110 is a functional section that reads image data input to the image-forming apparatus 10. Moreover, the image inputter 110 is coupled to the document reader 112 being a functional section that reads an image in a document, and receives image data output from the document reader 112.
The image inputter 110 may receive image data from a storage medium, such as a USB memory or an SD card. Furthermore, the image inputter 110 may receive image data from another terminal device via the communicator 170 that performs connection to the other terminal device.
The document reader 112 has a function of optically reading a document placed on a contact glass (not illustrated), and supplying scan data to the image processor 120.
The image former 130 is a functional section that forms, on a recording medium (for example, a recording sheet), output data based on the image data. For example, as illustrated in
In the electrophotographic process of the image former 130, the optical scanning device 200, described below, forms an electrostatic latent image by performing scanning with a laser beam (corresponding to laser light) corresponding to image data on a surface of a photoconductor drum (image carrier) (not illustrated), develops the electrostatic latent image with toner, and transfers and fixes a developed toner image onto a recording medium, so as to form an image.
The image processor 120 has a function of converting image data read by the document reader 112 to have a set file format (TIFF, GIF, JPEG, or the like). Then, the image processor 120 forms an output image based on the image data subjected to the image processing.
The operation processor 140 is a functional section that receives operational instructions issued by a user, and includes various key switches and a device that detects a touch input. The user uses the operation processor 140 to input a function to be used and an output condition.
The display 150 is a functional section that displays various types of information for the user, and includes, for example, a liquid crystal display (LCD).
Specifically, the operation processor 140 provides a user interface for operating the image-forming apparatus 10. The display 150 displays various setting menu screens of the image-forming apparatus 10 and messages.
Note that, as illustrated in
The storage 160 is a functional section that stores various programs including a control program required for operation of the image-forming apparatus 10, various data including the read data, and user information. The storage 160 includes, for example, at least one nonvolatile read only memory (ROM), at least one random access memory (RAM), and at least one hard disk drive (HDD). The storage 160 may further include a solid state drive (SSD) which is a semiconductor memory.
The communicator 170 performs a communication connection with an external device. A communication interface (communication I/F) used for sending and receiving data is provided as the communicator 170. With the communication I/F, data which is stored in the storage 160 of the image-forming apparatus 10 may be sent to and received from any other computer device connected via a network in response to an operation performed by the user on the image-forming apparatus 10.
As illustrated in
Furthermore,
As illustrated in
The laser emitter 200a includes a plurality of laser emitting elements, and a light amount detector 280 including a photodiode (PD) detects an amount of light emitted from the laser emitting elements.
A reference clock signal generator 200m generates a reference clock signal for control. A beam detection (BD) sensor 200k is disposed on a starting end side of a scanning area of a light beam and controls a timing when an electrostatic latent image is written on the photoconductor drum. Note that, In
As illustrated in
As illustrated in
In the surface-crossing exposure segment light amount corrector 250, a light amount correction value calculator 250a calculates a light amount correction value of a surface-crossing exposure segment based on image data subjected to the bow correction by the bow corrector 230, a PDM generator 250b converts the light amount correction value into a PDM signal, a filter circuit 290b converts the light amount correction value into an analog signal, and then the analog signal is input to a superimposing circuit 260. Note that, as will be described below with reference to
Furthermore, in the shading corrector 300, a correction value setter 300a sets a shading correction value obtained in advance through an experiment or the like, and a PDM generator 300b converts the shading correction value into a PDM signal and inputs the PDM signal to a filter circuit 290a. The filter circuit 290a converts the shading correction value represented by the PDM signal into an analog signal, and then input the analog signal to the superimposing circuit 260. The superimposing circuit 260 outputs a light amount correction signal (Vsw) serving as a reference signal of a laser driver 210.
Processes of the individual sections will be described in detail below.
The electronic bow correction performed by the bow corrector 230 will be described with reference to
Specifically, even when input image data does not have a curve in the sub-scanning direction as illustrated in
As illustrated in
In a light emitter employing a multi-beam method including a plurality of laser light emitting elements, a phenomenon called reciprocity failure in which an area where scanning operations overlap becomes dense changes a distribution in which the density becomes dense in a dither pattern, and thus the density level difference occurs.
For example, in
According to
As illustrated in
In the first embodiment, a PDM shading signal for the bow correction used for the density correction is a density correction signal based on a PDM signal set to correct an amount of light so as to remove density unevenness caused by the reciprocity failure at a light emission timing of the plurality of light emitting elements. The correction of the light amount at the light emission timing of the plurality of light emitting elements so as to remove the density unevenness caused by the reciprocity failure has the same meaning as correction of a light amount of a surface-crossing exposure segment.
In addition, in the light amount correction of the surface-crossing exposure segment by an opposite phase, specifically, an image is output in a state in which both the bow correction and the light amount correction are performed on the surface-crossing exposure segment, and a pattern of a density smoothing process which will be described below is selected so that a shading difference is eliminated. Accordingly, a phase of the light amount correction of the surface-crossing exposure segment is opposite to that of the image subjected to the bow correction and the density smoothing process.
As an image of the density correction, any image is processed in the same manner according to a pattern of the density smoothing process obtained experimentally, and the light amount correction of the surface-crossing exposure segment is performed according to the presence or absence of the surface-crossing exposure. If there is no slide in the sub-scanning direction between adjacent segments in the bow correction, the density smoothing process is practically invalid between the segments.
In the density smoothing process, as illustrated in a micro-level image of
When only the bow correction is performed, the following problem occurs. Therefore, a streak image is likely to be generated in an item of the bow correction, and thus the density smoothing process is performed. Specifically, there arise problems in that synchronization between the density correction and the bow correction may not be easily realized, highly accurate density correction considering various variations may not be easily realized, and so on, since the portion is affected by magnification correction and asynchronism of the density correction circuit.
Here, in
As illustrated in
A reference clock (200m) and a BD signal (200k) are input to the laser scanning unit 220a.
In the laser scanning unit 220a, the bow corrector 230 performs the electronic bow correction process in response to a control signal supplied from the at least one controller 100. The density smoothing processor 240 performs the density smoothing process on an image subjected to the bow correction process in response to an instruction issued by the at least one controller 100. The surface-crossing exposure segment light amount corrector 250 performs the density correction with respect to the reciprocity failure on the image subjected to the electronic bow correction performed by the bow corrector 230. The shading corrector 300 performs the shading correction process on the image. Therefore, the shading corrector 300 generates a shading correction signal Vshade, the bow corrector 230 generates a control signal (digital signal), such as a bow correction signal Vbow for the electronic bow correction, and the laser driver controller 270 controls output of control signals (such as signals for bow correction, density correction by light amount correction of the surface-crossing exposure segment, and shading correction) to be input to the laser driver 210. Based on the control signal output from the laser driver controller 270, the laser driver 210 controls a multi-beam light emitting operation of the laser emitter 200a.
The laser scanning unit 220a is configured as an application-specific integrated circuit (LSU ASIC). The integrated circuit (LSU ASIC) of the laser scanning unit 220a receives a control signal supplied from the at least one controller 100, image data, a horizontal synchronization signal HSYNC, a reference clock signal supplied from the reference clock signal generator 200m, a detection signal supplied from the beam detection (BD) sensor 200k, and the like.
The Vshade signal is an analog voltage signal for shading.
The shading corrector 300 of the laser scanning unit (LSU) 220a outputs a shading correction value read from a table (stored in the storage 220b, such as an EEPROM) set in the correction value setter 300a as a PDM wave signal via the PDM generator 300b. The PDM wave signal of the shading correction value is converted into an analog shading voltage signal (Vshade) by an external filter circuit 290a, and is input to the superimposing circuit 260. Note that the shading correction value is obtained in advance by an experiment or the like, and may be stored in the ROM or the like of the storage 160 of the image-forming apparatus 10 in addition to the storage 220b.
The Vbow signal is an analog voltage signal for the bow correction.
The bow corrector 230 of the laser scanning unit (LSU) 220a outputs a bow correction PDM signal, which is converted into the analog bow correction voltage signal (Vbow) by the external filter circuit 290b and input to the superimposing circuit 260.
A signal obtained by superimposing the analog shading voltage signal (Vshade) and the analog bow correction voltage signal (Vbow) by the superimposing circuit 260 is input to the laser driver 210 to control and correct multi-beam light emission.
Furthermore, the surface-crossing exposure segment light amount corrector 250 calculates a correction value of a light amount in the surface-crossing exposure segment (correction value calculator 250a). The calculated light amount correction value is input to the laser driver 210 as a light amount correction signal via the PDM generator 250b and a filter circuit (not illustrated), and the multi-beam light emission is controlled and corrected by the laser driver 210.
The light amount correction signal (Vsw) to be input to the laser driver 210 is obtained by the following formula (1) based on the principle of superimposition of the Vshade signal and the Vbow signal performed by the superimposing circuit 260 including the resistors Ra, Rb, and Rc.
In the case of
In
1.5.7 Relationship between Density Correction and Number of Segments
First, as illustrated in
In the density correction, the number of segments for the density correction is larger than the number of segments for the bow correction/density smoothing process.
The reason why the number of segments for the density correction is larger than the number of segments for the bow correction/density smoothing process will now be described. This is because, as illustrated in
As for final density, as illustrated in
Although a phenomenon in which an area subjected to scanning in an overlapping manner becomes dense, which is called reciprocity failure, is required to be corrected, when an adjustment pitch of the end-side LD varies, density correction according to the pitch is required. For example, in a case of a configuration of 2400 dpi with eight beams, as illustrated in a table of
The image-forming apparatus according to the first embodiment can suppress a density level difference by performing the density smoothing process and the density correction on image data so that the density level difference does not occur in a halftone image due to influence of the reciprocity failure even when the electronic bow correction is performed.
In the first embodiment, in an image-forming apparatus that performs the electronic bow correction, a density level difference is smoothed by the density smoothing process, and at the same time, the density correction is performed by the shading process (refer to
According to the first feature point, synchronization between the density correction and the bow correction is not required, and a streak image is not generated at a boundary of the bow correction (refer to
The shading process for the density correction is performed by the PDM method (refer to
According to the second feature point, the density correction can be realized by the light amount correction process performed on a surface-crossing exposure segment with the simple circuit configuration including the PDM generator 250b and the filter circuit 290b.
In a third feature point, the number of segments for the density correction is larger than the number of segments for the density smoothing process in the configuration of the first feature point (refer to
According to the third feature point, even when a halftone region is interrupted in the middle of the number of segments in the density smoothing process, a density correction amount does not deviate.
In a fourth feature point, the density correction amount is varied according to the adjustment pitch of the end-side LD affected by the reciprocity failure in the configuration of the first feature point (refer to
According to the fourth feature point, the density correction can be performed in accordance with a degree of influence of the reciprocity failure.
An image-forming apparatus according to a second embodiment will be described. Note that the image-forming apparatus according to the second embodiment has substantially the same configuration as the image-forming apparatus according to the first embodiment and is different from the image-forming apparatus according to the first embodiment in a density smoothing process. Components having the same configurations are denoted by the same reference numerals, and description thereof will be omitted.
In the second embodiment, in an optical scanning device 200 illustrated in
Specifically, in the second embodiment, as illustrated in
In the second embodiment, the bow corrector 230 performs an electronic bow correction process on image data. The density smoothing processor 240 performs a density smoothing process on an image subjected to the bow correction process based on an instruction issued by the at least one controller 100. The surface-crossing exposure segment light amount corrector 250 performs the density correction by performing surface-crossing exposure segment light amount correction on the image subjected to the bow correction process. The shading corrector 300 performs a general shading correction process.
The at least one controller 100 smooths a density level difference of an image by controlling the density smoothing processor 240 in accordance with a change rate of density correction of the surface-crossing exposure segment light amount corrector 250 (controlling a selection of one of TONE patterns illustrated in
The density smoothing process is performed by the density smoothing processor 240 in a unit of 600 dpi, and determines some of the patterns to be processed illustrated in
That is, as described above with reference to
As described above, the reason why the density smoothing process is performed is to cope with problems, such as a case where, since a portion is affected by a magnification correction and asynchronism of a density correction circuit, synchronization between the density correction and the bow correction may not be easily realized, and a case where highly accurate density correction considering various variations may not be easily realized. However, when only the density smoothing process is uniformly performed using a single pattern as illustrated in
Therefore, in the second embodiment, in order to prevent the density unevenness caused by the density smoothing process, a pattern corresponding to the density change rate is appropriately selected from the plurality of patterns for the density smoothing process to prevent the density unevenness.
In the example of the second embodiment, as illustrated in
Specifically, an image slide cycle of the density smoothing process is set to a range of 1 to 15 dots in 600 dpi terms.
Thus, since switching is performed in a unit larger than 1 dot of 600 dpi, dots are less likely to be isolated, and white streaks are less likely to occur. Furthermore, since the switching is performed in a unit smaller than the 15 dots of 600 dpi, a banding phenomenon is less likely to occur.
TONE patterns (TONE patterns 1 to 12 are illustrated in
Among TONE patterns 1 to 12 illustrated in
TONE pattern 2 includes two sets of a non-sliding region of 7 dots and a region of 1 dot which is slid with respect to the non-sliding region of 7 dots.
TONE pattern 3 includes non-sliding region of 5 dots and a region of 1 dot which is slid with respect to the non-sliding region of 5 dots, and a block, which is arranged adjacent to the sliding region of 1 dot, of two sets of a non-sliding region of 4 dots and a region of 1 dot which is slid with respect to the non-sliding region of 4 dots.
TONE pattern 4 includes four sets of a non-sliding region of 3 dots and a region of 1 dot which is slid with respect to the non-sliding region of 3 dots.
TONE pattern 5 includes a non-sliding region of 3 dots, a region of 1 dot which is slid with respect to the non-sliding region of 3 dots, and a block, which is arranged adjacent to the sliding region of 1 dot, of four sets of a non-sliding region of 2 dots and a region of 1 dot which is slid with respect to the non-sliding region of 2 dots.
TONE pattern 6 includes a first block of four sets of a non-sliding region of 2 dots and a region of 1 dot which is slid with respect to the non-sliding region of 2 dots, and a second block, which is arranged adjacent to the first block, of two sets of a non-sliding region of 1 dot and a region of 1 dot which is slid with respect to the non-sliding region of 1 dot.
TONE pattern 7 includes a first block of two sets of a non-sliding region of 2 dots and a region of 1 dot which is slid with respect to the non-sliding region of 2 dots, and a second block, which is arranged adjacent to the first block, of five sets of a non-sliding region of 1 dot and a region of 1 dot which is slid with respect to the non-sliding region of 1 dot.
TONE pattern 8 includes eight sets of a non-sliding region of 1 dot and a region of 1 dot which is slid with respect to the non-sliding region of 1 dot.
TONE pattern 9 includes a first block of five sets of a non-sliding region of 1 dot and a region of 1 dot which is slid with respect to the non-sliding region of 1 dot, and a second block, which is arranged adjacent to the first block, of two sets of a non-sliding region of 1 dot and a region of 2 dots which is slid with respect to the non-sliding region of 1 dot.
TONE pattern 10 includes a first block of two sets of a non-sliding region of 1 dot and a region of 1 dot which is slid with respect to the non-sliding region of 1 dot, and a second block, which is arranged adjacent to the first block, of four sets of a non-sliding region of 2 dots and a region of 1 dot which is slid with respect to the non-sliding region of 2 dots.
TONE pattern 11 includes a block of four sets of a non-sliding region of 1 dot and a region of 2 dots which is slid with respect to the non-sliding region of 1 dot, and a set, which is arranged adjacent to the block, of a non-sliding region of 1 dot and a region of 3 dots which is slid with respect to the non-sliding region of 1 dot.
TONE pattern 12 includes four sets of a non-sliding region of 1 dot and a region of 3 dots which is slid with respect to the non-sliding region of 1 dot.
In TONE patterns illustrated in
TONE pattern 14 includes two sets of a non-sliding region of 1 dot and a region of 7 dots which is slid with respect to the non-sliding region of 1 dot.
TONE pattern 15 includes a non-sliding region of 1 dot and a region of 15 dots which is slid with respect to the non-sliding region of 1 dot.
TONE patterns of the embodiment described above are examples, and other TONE patterns may be set. For example, the number of dots in the main scanning direction and the dot width may be modified and set to other values.
An image subjected to only the bow correction and the density correction for the bow correction is output, and patterns of the density smoothing process (TONE patterns in
It is assumed that, when the image-forming apparatus employs the first process speed, image density distribution illustrated in
As a selection of patterns of the density smoothing process, as illustrated in
In the region of the second inclination Δ2, since the inclination of the density correction is large, the density change rate is large, and TONE patterns are set in order of TONE pattern 3, TONE pattern 5, TONE pattern 7, TONE pattern 9, TONE pattern 11, and TONE pattern 13.
In the region of the third inclination Δ3, since the inclination of the density correction is small, the density change rate is small, and TONE patterns are set in order of TONE pattern 14, TONE pattern 14, TONE pattern 15, and TONE pattern 15.
It is assumed that, when the image-forming apparatus employs the second process speed which is slower than (different from) the first process speed, image density distribution illustrated in
As a selection of patterns of the density smoothing process, as illustrated in
In the region of the second inclination Δ2, since the inclination of the density correction is large, the density change rate is large, and TONE patterns are set in order of TONE pattern 4, TONE pattern 7, TONE pattern 10, and TONE pattern 12.
In the region of the third inclination Δ3, since the inclination of the density correction is small, the density change rate is small, and TONE patterns are set in order of TONE pattern 14, TONE pattern 14, and TONE pattern 15.
In the region of the fourth inclination Δ4, since the inclination of the density correction is zero, the density change does not occur, and TONE patterns are set in order of TONE pattern 15, TONE pattern 15, TONE pattern 15, and TONE pattern 15.
The image-forming apparatus according to the embodiment performs the density smoothing process in accordance with a change rate of density correction in a configuration in which density level difference is suppressed by performing the density smoothing process and the density correction so that a density level difference is not generated in a halftone image due to influence of reciprocity failure even when the electronic bow correction is performed. Therefore, density unevenness may be suppressed in a density smoothing process region.
In the configuration of the first feature point, an image slide cycle of the density smoothing process is set to a range of 1 to 15 dots in 600 dpi terms. Since switching is performed in a unit larger than 1 dot of 600 dpi, dots are less likely to be isolated, and white streaks are less likely to occur. Furthermore, since the switching is performed in a unit smaller than the 15 dots of 600 dpi, a banding phenomenon is less likely to occur, which is excellent operation effect.
With the configuration of the first feature point, a pattern of the density smoothing process is switched according to a process speed. Consequently, even when the process speed is changed, the density unevenness in the density smoothing region can be suppressed.
An image-forming apparatus according to a third embodiment will be described. Note that the image-forming apparatus according to the third embodiment has a configuration similar to the image-forming apparatus according to the first embodiment and is different from the image-forming apparatus according to the first embodiment in a configuration of an optical scanning device 1200. Components having the same configurations are denoted by the same reference numerals, and description thereof will be omitted.
As illustrated in
Furthermore,
The optical scanning device 1200 is obtained by adding an exposure ratio calculator 310, a detector 320, and an environmental sensor 320a to the optical scanning device 200 (refer to
As illustrated in
Note that the optical scanning device 1200 includes a surface-crossing exposure ratio calculator 310 that divides data into a plurality of blocks in a main scanning direction of the data, and calculates, for each block, a rate of the surface-crossing exposure in which the reciprocity failure occurs in one scanning operation.
The laser emitter 200a includes a plurality of laser emitting elements, and a light amount detector 280 including a photodiode (PD) detects an amount of light emitted from the laser emitting elements.
A reference clock signal generator 200m generates a reference clock signal for control. Abeam detection (BD) sensor 200k is disposed on a starting end side of a scanning area of a light beam and controls a timing when an electrostatic latent image is written on the photoconductor drum. Note that, in
In the third embodiment, the detector 320 is configured such that an environmental sensor 320a for detecting temperature-humidity data inside the image-forming apparatus is installed inside the image-forming apparatus, and the detector 320 acquires the temperature-humidity data based on a signal output from the environmental sensor 320a.
In addition, a film loss amount of the photoconductor drum is acquired by the detector 320 based on data of use history of the photoconductor drum stored in the storage 160, for example, history of the number of rotations after the photoconductor drum is installed in the device.
The surface-crossing exposure segment light amount corrector 250 calculates a correction amount using a correction coefficient corresponding to the surface-crossing exposure ratio, a correction coefficient corresponding to temperature and humidity, a correction coefficient corresponding to the number of drum rotations, and a correction coefficient corresponding to the light emission rate of printing. The surface-crossing exposure segment light amount corrector 250 obtains a correction coefficient to be used by itself using a correction coefficient table stored in a corresponding storage region in the storage 160. The correction coefficient table may be stored in a storage 220b, such as an EEPROM, of the laser scanning unit 220a, in addition to the storage 160.
That is, as storage regions of the storage 160, a storage region for storing a table of correction coefficients corresponding to the surface-crossing exposure ratios, a storage region for storing a table of correction coefficients corresponding to film loss amounts of the drum, a storage region for storing a table of setting values of an environmental area corresponding to the temperature-humidity data in the image-forming apparatus, and a storage region for storing a table of correction coefficients of temperature and humidity obtained from the setting values of the environmental area are generated and set. The surface-crossing exposure segment light amount corrector 250 obtains a correction light amount using the individual correction coefficients obtained from the individual tables, and the laser driver controller 270 corrects a light amount of an image signal input to the laser driver 210 in accordance with the correction light amount.
As illustrated in
As illustrated in
The laser scanning unit 220a is configured as an application-specific integrated circuit (LSU ASIC). The integrated circuit (LSU ASIC) of the laser scanning unit 220a receives a control signal supplied from the at least one controller 100, image data, a horizontal synchronization signal HSYNC, a reference clock signal supplied from the reference clock signal generator 200m, a detection signal supplied from the beam detection (BD) sensor 200k, and the like.
Next, concrete control examples will be described as first to third examples.
In the first example, the laser light amount is corrected based on the exposure ratio obtained when the reciprocity failure occurs, a state of the laser emitter (laser emitting element LD), and the like.
Feature points of the first example are as follows.
As illustrated in
In the first example, as shown in
Specifically, the image data is divided into a plurality of blocks in the main scanning direction, a surface-crossing exposure ratio which is a ratio in which surface-crossing exposure that causes the reciprocity failure by one scanning operation is included is calculated for each block (exposure ratio calculator 310), temperature and humidity data in the device and a film loss amount of the photoconductor drum are acquired (detector 320), and a light amount of the multi-beams in the block is corrected in accordance with the calculated surface-crossing exposure ratio, the acquired temperature and humidity data, and the film loss amount of the photoconductor drum (surface-crossing exposure segment light amount corrector 250).
The exposure ratio calculator 310 obtains a count of the reciprocity failure that occurs in the surface-crossing exposure by a beam light emitted from an end light emitting element in the plurality of light emitting elements in a segment of the laser emitter (light source unit) 200a.
In the exposure ratio calculator 310, as the count of the reciprocity failure, a count of surface-crossing exposure is obtained based on the number of timings at which a light emission timing of one light emitting element overlaps a light emission timing of the other light emitting element among the end portion light emitting elements that perform the surface-crossing exposure, and the surface-crossing exposure ratio is calculated based on the count. A specific method for obtaining the surface-crossing exposure ratio will be described with reference to
In
Since the surface-crossing exposure occurs when both the waveforms rise upward (when both of the laser light emitting elements LD8 and LD1 emit light in an ON state), the exposure ratio calculator 310 counts the number of simultaneous light emissions in which both the signal waveforms rise upward, and the count number (MATCH_CNT) serves as the number of surface-crossing exposures. Then, based on the number of simultaneous light emissions with respect to the total count number (Counter), the surface-crossing exposure ratio (MATCH_RATIO) at which the surface-crossing exposure occurs can be calculated.
In the example of
A correction light amount (Ldebc_N) corresponding to the surface-crossing correction coefficient, the temperature-humidity data (environmental data) in the device, and the film loss amount of the photoconductor drum is calculated from the following expression (2).
Here, ev indicates a correction coefficient corresponding to temperature and humidity, Cx indicates a correction coefficient corresponding to the film loss amount of the photoconductor drum, and r_N denotes a correction coefficient corresponding to the surface-crossing exposure ratio of printing.
These correction coefficients can be calculated using, for example, tables illustrated in
As illustrated in
In
The correction coefficient r_N is obtained from the surface-crossing exposure ratio illustrated in the example of
The correction light amount (Ldebc_N) is calculated in accordance with Expression (2) using the correction coefficient ev corresponding to the temperature-humidity, the correction coefficient Cx corresponding to the film loss amount of the photoconductor drum, and the correction coefficient r_N corresponding to the surface-crossing exposure ratio which are obtained from the respective table examples illustrated in
According to the first example, since the individual correction coefficients are obtained from the corresponding tables, a correction amount is not required to be calculated. Therefore, the problem of the density unevenness may be solved with a relatively small calculation amount, which is an operation effect.
Note that, in the light amount correction, it is preferable to correct a light amount of at least one of the end light emitting elements (LD8 and LD1 in the case of eight LDs in the segment) in the segment of the laser light emitter, and to reduce the light amount as the surface-crossing exposure ratio in the segment increases. When the light amount correction control of both the end light emitting elements is selected, the density is easily changed, and when one of them is controlled, signal processing can be simplified.
In the second example, correction is performed by changing the correction coefficient corresponding to the film loss amount of the photoconductor drum calculated by the same technique as in the first example and the environmental correction coefficient (temperature-humidity coefficient) in accordance with density (pixel density). Specifically, in the light amount correction, a correction amount is calculated using a correction coefficient corresponding to temperature and humidity, a correction coefficient corresponding to the number of drum rotations, and a correction coefficient corresponding to the light emission ratio of printing.
Feature points of the second example are as follows.
Note that the feature points [a], [c], [d], and [e] are the same as those in the first example.
In the second example, in the calculation of the printing density in the region of the item [f], average densities of images in individual regions are digitally calculated before printing in the image data divided into the blocks (divided into the regions) as illustrated in
Furthermore, in Expression (2), the correction coefficient Cx corresponding to the film loss amount is calculated in accordance with the correction count corresponding to the film loss and the image average density, for example, as in the table illustrated in
The correction coefficient ev corresponding to the temperature and humidity in the device is calculated in accordance with the environmental area corresponding to the density and humidity and the image average density as in the table illustrated in
In the second example, since the correction coefficient is calculated in accordance with the image average density, the correction can be performed even when a toner adhesion amount is increased, the film thickness is reduced, and the environmental correction is extremely changed.
In the third example, printing is performed on a transfer member (intermediate transfer member) by converting the light amount, the density of the printed image is read by an image sensor, and the light amount is corrected based on the read density.
Feature points of the third example are as follows.
The patch is read by an imaging sensor (not illustrated), such as a charge-coupled device (CCD) camera.
A difference between the obtained correction amount (correction coefficient) and the correction coefficient r_N illustrated in
Note that, since the patches of the case [j] without the surface-crossing exposure segment and the case [k] with the surface-crossing exposure segment are printed, the printed patches are read by the density sensor [l], and the correction value is changed [m] to [o] from the change of individual read patch densities, the density correction can be accurately performed in accordance with a printing situation which is different according to a condition, such as an environment.
An actual operation is performed also with reference to the table of
The third example can cope with a variation occurring in each apparatus. Since the difference is stored, the storage region can be reduced, which is an operation effect.
Note that, according to the embodiment, the light amount is corrected by using the correction coefficient corresponding to the temperature and humidity and the correction coefficient corresponding to the film loss amount of the drum as the environmental data, but the present disclosure is not limited thereto. In the light amount correction, at least one of the correction coefficient corresponding to the temperature and humidity and the correction coefficient corresponding to the film loss amount of the drum can be adjusted based on image data. Accordingly, only a required portion may be adjusted, and a control load is reduced.
Furthermore, the light amount correction can be performed by obtaining pixel density based on image data, specifying a region having a pixel density equal to or higher than a threshold value, and adjusting an exposure amount of a block corresponding to the specified region. Accordingly, density unevenness is specified and a light amount of only a block may be corrected, so that a calculation and a control load are reduced.
Although the embodiments have been described, specific configurations are not limited to the configurations of the embodiments, and designs or the like to the extent that they do not depart from the gist of the present disclosure are also included in the scope of the claims.
Furthermore, the program that operates in each device in the embodiments is a program that controls a CPU or the like (a program that causes a computer to function) in a manner to realize the functions of the above embodiments. Moreover, information handled by these devices is temporarily stored in a temporary storage device (for example, a RAM) when being processed, and then stored in various storage devices, such as a ROM and an HDD, where the information is read, corrected, and written by the CPU as needed.
Here, a recording medium for storing the program may be any non-transitory recording medium, such as a semiconductor medium (for example, a ROM or a nonvolatile memory card), an optical recording medium, such as an optical recording medium or a magneto-optical recording medium (for example, a digital versatile disc (DVD), a magneto optical disc (MO), a mini disc (MD), a compact disc (CD), or a Blu-ray (registered trademark) disc), or a magnetic recording medium (for example, a magnetic tape or a flexible disk).
Furthermore, the functions of the present disclosure may also be realized not only by executing the loaded programs but also processing in cooperation with the operating system, other application programs, or the like in accordance with the instructions of the programs.
Furthermore, in the case of distribution of the program to the market, the program can be stored and distributed in a portable storage device, or transferred to a server computer connected via a network, such as the Internet. In this case, a storage device of the server computer is also included in the present disclosure as a matter of course.
In addition, some or all of the devices in the above-described embodiments may be realized as an LSI (Large Scale Integration), which is typically an integrated circuit. Respective functional blocks of the apparatuses may be individually formed as a chip, or may be partially or wholly integrated and formed as a chip. Furthermore, a method of achieving the integrated circuit is not limited to the LSI, but may be realized by a dedicated circuit or by a general-purpose processor. In addition, when a technology for achieving the integrated circuit which substitutes for the LSI emerges as a result of the progress of the semiconductor technology, it is of course possible to use an integrated circuit based on such a technology.
While there have been described what are at present considered to be certain embodiments of the invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claims cover all such modifications as fall within the true spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-012365 | Jan 2023 | JP | national |
| 2023-012366 | Jan 2023 | JP | national |
| 2023-012367 | Jan 2023 | JP | national |
