Patent Grant
10990029
The present invention relates to electrophotographic image forming apparatuses such as a laser beam printer, a digital copier, and a digital FAX (facsimile machine).
In an image forming apparatus, the image density in the main scanning direction is not uniform due to several reasons. For example, a developing apparatus that performs development by attaching toner to an electrostatic latent image, in the image forming apparatus, causes toner particles to be charged by friction between a developing sleeve and toner particles. In order to make the image density uniform in a main scanning direction, toner particles need to be uniformly charged in a longitudinal direction (main scanning direction) of the developing sleeve without the toner particles being excessively charged. Here, on an end portion side of the developing sleeve in the main scanning direction, the flowability of toner particles decreases due to the resistance of a side wall, and the flow speed of the toner particles decreases relative to those on a central side of the developing sleeve. Therefore, toner particles on the end portion side are in contact with the developing sleeve for a period longer than those on the central portion side, and are likely to be more charged than those on the central portion side. As a result, the density at the end portion in the main scanning direction decreases relative to that in the central portion.
U.S. Pat. No. 5,274,426 discloses a configuration in which toner particles can be uniformly charged by changing the content ratio of conductive fine particles between a central portion and an end portion of a coating layer of the developing sleeve, or by differentiating the polishing processing of the coating layer.
However, the configuration in U.S. Pat. No. 5,274,426 complicates the structure and configuration of the developing sleeve, and the cost of the image forming apparatus increases.
As shown in the example described above, in an image forming apparatus, the image density in the main scanning direction is not uniform due to several factors. That is, the density may change along the main scanning direction.
According to an aspect of the present invention, an image forming apparatus includes: a photosensitive member; a scan unit configured to scan the photosensitive member with light based on image data, and form a latent image on the photosensitive member; a developing unit configured to form an image on the photosensitive member by attaching toner to the latent image formed on the photosensitive member; and a correction unit configured to correct an exposure amount of the photosensitive member such that a density change of the image in a main scanning direction due to a configuration of the scan unit and a density of the image to be formed is reduced.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, illustrative embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are illustrative and do not limit the present invention to the contents of the embodiments. Also, in the following diagrams, constituent elements that are not required for describing the embodiments are omitted.
The light flux that has passed through the anamorphic lens 404 is reflected by a reflective surface 405a of the deflector (polygon mirror) 405. The light beam 410 reflected by the reflective surface 405a passes through an imaging lens 406, and forms a predetermined spot-like image (hereinafter, referred to as a “spot”) on the surface of the photosensitive member 4. As a result, the photosensitive member 4 is irradiated with light and exposed. By rotating the deflector 405 at a constant angular velocity in the direction of arrow Ao using a drive unit that is not illustrated, the spot moves in the main scanning direction on a scan surface 407 of the photosensitive member 4, and forms a latent image on the scan surface 407. Note that the main scanning direction is a direction parallel to the rotation axis of the photosensitive member 4. Also, the sub-scanning direction is the circumferential direction of the photosensitive member 4.
A beam detector (hereinafter referred to as “BD”) sensor 409 and a BD lens 408 constitute a synchronization optical system that determines the timing for writing the electrostatic latent image onto the scan surface 407. The light beam 410 that has passed through the BD lens 408 is incident on the BD sensor 409, which includes a photodiode, and is detected. The write timing with respect to the photosensitive member 4 (timing of forming a latent image) is controlled based on the timing at which the light beam 410 is detected by the BD sensor 409. The light source 401 of the present embodiment includes one light emitting unit, but the light source 401 may include a plurality of light emitting units that can be independently controlled to emit light.
As shown in
In the present embodiment, the imaging lens 406 does not have so-called fθ characteristics. That is, the spot does not move at a uniform speed on the scan surface 407 when the deflector 405 is rotated at a uniform angular velocity. As a result of using the imaging lens 406 that does not have fθ characteristics, it is possible to dispose the imaging lens 406 close to the deflector 405 (at a position at which a distance D1 is small). Also, with the imaging lens 406 that does not have fθ characteristics, a length (width LW) in the main scanning direction and a length (thickness LT) in the optical axis direction can be reduced relative to the case of an imaging lens having fθ characteristics. Accordingly, the size of the optical scanning apparatus 400 can be reduced. Also, there are cases where the shapes of the incident surface and the emission surface of a lens having 10 characteristics change sharply when viewed in a cross-section in the main scanning direction. When the shape is restricted in this way, favorable imaging performance may not be obtained. In contrast, the imaging lens 406 does not have fθ characteristics, and the shapes of the incident surface and the emission surface viewed in a cross-section in the main scanning direction do not have many sharp changes, and as a result, favorable imaging performance can be obtained. Note that the imaging lens 406 may be a lens that has fθ characteristics in some portions in the main scanning direction, and does not have fθ characteristics in other regions.
Note that it is assumed that, in the following description, the surface potential (charged potential) (Vd) of the photosensitive member 4 charged by a charging unit that is not illustrated is −450 V, and the developing potential (Vdc) that a developing unit that is not shown in
Also, the time taken for scanning a unit length at an image height in the vicinity of the outermost off-axis image height on the scan surface 407 is shorter than the time taken for scanning a unit length at an image height in the vicinity of the on-axis image height. This means that, when the emission luminance of the light source 401 is fixed, the total exposure amount per unit length (hereinafter, simply referred to as “exposure amount per unit length”) at an image height in the vicinity of the outermost off-axis image height is smaller than the exposure amount per unit length at an image height in the vicinity of the on-axis image height. Therefore, in the present embodiment, luminance correction is performed in addition to partial magnification correction described above, in order to obtain preferable image quality.
Partial Magnification Correction
Next, the partial magnification correction will be described. Prior to the description, the reason why partial magnification correction is necessary and the correction principle will be described using
The CPU 2 of the control unit 1 changes the frequency of a clock signal VCLK 113 that is transmitted to the image processing unit 101 of the image signal generation unit 100 according to the position in the main scanning direction in order to correct the cycle and time width of the VDO signal 110. With this, partial magnification correction is performed.
Note that the partial magnification correction is not limited to the method in which the clock frequency ratio of the clock signal VCLK 113 is changed according to the partial magnification, as described above. For example, in a configuration in which exposure is performed in units of a pixel piece obtained by dividing one pixel into a plurality of pieces, partial magnification correction can be performed by inserting or omitting a pixel piece according to the partial magnification (image height).
Luminance Correction
Next, luminance correction will be described. The partial magnification correction described above performs correction such that exposure time for one pixel is reduced as the absolute value of the image height increases. Therefore, the total exposure amount (integrated light amount) for one pixel decreases as the absolute value of the image height increases. The luminance correction is performed to compensate this reduction. Specifically, the luminance (light emission intensity) of the light source 401 is corrected such that the total exposure amount (integrated light amount) for one pixel is the same regardless of the image height. The control unit 1 in
The control unit 1 outputs a luminance correction analog voltage 312 that changes in one scan line in synchronization with the BD signal 111 based on the luminance correction information. The VI converter circuit 306 converts the luminance correction analog voltage 312 to a current and outputs the current to the laser driver 307. The laser driver 307 performs so-called APC (Auto Power Control), and automatically adjusts the luminance of the light emitting unit 11 to a desired luminance. Note that, as shown in
It was found that, in the configuration described above, particularly in a region in which the density is high (on solid side), the density increases as the image height increases, and as a result, the image density, including half tones, is not uniform in the main scanning direction. In the following, the reason why the density is not uniform in the main scanning direction will be described using a configuration in which only the partial magnification correction and luminance correction are performed, as Comparative example 1. Note that, in the present embodiment, it is assumed that the spot diameter is 60 μm at the on-axis image height, and is 90 μm at the outermost off-axis image height.
Comparative example 1 is a configuration in which luminance correction is performed such that the total exposure amount (integrated light amount) of one pixel is constant regardless of the image height.
Next, consider the photosensitive member potential (exposure potential) of the photosensitive member 4 when the exposure amount changes.
When the spot diameter is 60 μm, the photosensitive member potential changes in a range from −130 to −180 V, approximately, and the average potential is −152.7 V. On the other hand, when the spot diameter is 90 μm, the photosensitive member potential changes in a range from −147 to −150 V, approximately, and the average potential is −148.7V. Therefore, the average potential differs by approximately 4 V between the spot diameter of 90 μm and the spot diameter of 60 μm. The developing potential (Vdc) is −250V, in the present embodiment, and the developing contrast is approximately 100V, and therefore, the contrast differs by approximately 4% (4 V) between the spot diameter of 90 μm and the spot diameter of 60 μm. As a result, the density changes in the main scanning direction due to this contrast difference.
In the present embodiment, density correction processing, which will be described in the following, is performed in order to suppress the density difference described above.
The half-tone processing performed by the half tone processing unit 101a will be described. The half tone processing unit 101a uses a dither matrix constituted by nine pixels (pixels a to i), that is, three pixels in the main scanning direction (left-right direction in the diagram) and three pixels in the sub-scanning direction (up-down direction in the diagram), as shown in
The half tone processing unit 101a compares the tone value of each of the pixels a to i with threshold values, and outputs a corresponding level (0 to 31: 5 bits). For example, with respect to the pixel a, if the tone value is 144 or more, and less than 147, level 1 is output, and if the tone value is 147 or more, and less than 150, level 2 is output. That is, if the tone value is the threshold value associated with a certain level or more, and less than the threshold value associated with the level one level above the certain level, the certain level is output. Also, when the tone value is less than the threshold value associated with level 1, the half tone processing unit 101a outputs level 0. Also, with respect to the pixel a in
The position control unit 101b includes a position control matrix shown in
A PWM control unit 101c generates a pulse signal (VDO signal 110) corresponding to each pixel from the 7-bit data.
At tone value 171, the pixels a, c, g, and i reach level 10, the PWM value is 150, and the pixels emit light. Also, the pixels b, d, e, f, and h reach level 24, the PWM value decreases to 150, and the pixels emit light. That is, all the pixels emit light at the PWM value 150. From tone value 171 to tone value 255, the levels of all the pixels advance, and the light emission width monotonously increases. At tone value 255, all of the pixels reach level 31, the PWM value is 255, and light is emitted over the entire pixel widths thereof.
Next, density correction performed by the density correction processing unit 101z will be described. In the present embodiment, density correction information used by the density correction processing unit 101z is stored in the ROM 102. The density correction processing unit 101z corrects the tone value according to the position of the pixel in the main scanning direction such that a change in the image density in the main scanning direction shown in
A specific example of the density correction processing will be described. The uncorrected tone value in
The density correction information is information indicating the reduction amounts of tone values for each region for which density is reduced. Note that the density correction information may also be information indicating the correction amounts (change amount) of tone values regardless of whether or not the density has changed. In this case, the correction amount is 0 for the region in which density has not changed. The information indicating the correction amount indicates a value by which the tone value is changed, or a change ratio of the tone value, for example. Also, the configuration may be such that the density correction information is provided for each uncorrected tone value. In the example in
As described above, in the present embodiment, the optical scanning apparatus 400 is configured to scan the photosensitive member 4 with light whose scan speed changes according to the image height. Therefore, the control unit 1 performs partial magnification correction and luminance correction. Furthermore, the density correction processing unit 101z corrects the tone value based on density correction information in order to suppress the change in density caused by the change in the spot diameter of scan light on the photosensitive member 4 according to the image height. According to this configuration, the change in density in the main scanning direction, due to the configuration of the optical scanning apparatus 400, can be reduced. Note that the density correction information is created in advance and is stored in the ROM 101.
Next, a second embodiment will be described focusing on differences with the first embodiment. In the present embodiment, luminance correction is not performed. Therefore, the reference current determined by the APC need not to be corrected using the luminance correction analog voltage 312, and as a result, the exposure control configuration can be simplified. Since the luminance correction is not performed, the total exposure amount (integrated light amount) of one pixel at the outermost off-axis image height is 74%, when the total exposure amount at the on-axis image height is assumed to be 100%, as described in the first embodiment. In the present embodiment, the change in the total exposure amount is also cancelled out by density correction processing. That is, the luminance correction in the first embodiment is incorporated in the density correction in the first embodiment.
As described above, in the present embodiment, the optical scanning apparatus 400 is configured to scan the photosensitive member 4 with light whose scan speed changes according to the image height. Here, the present embodiment differs from the first embodiment in that the control unit 1 performs partial magnification correction, but does not perform luminance correction. Therefore, in the present embodiment, a change in density occurs that combines the change in density in the main scanning direction caused by the change in the exposure amount of the photosensitive member 4 due to the change in the scan speed, and the change in density caused by the change in the spot diameter of scan light on the photosensitive member 4 according to the image height. Therefore, the density correction information for suppressing this change in density is created, and is stored in the ROM 101 in advance. Also, the density correction processing unit 101z corrects the tone value based on the density correction information. According to this configuration, the change in density in the main scanning direction due to the configuration of the optical scanning apparatus 400 can be reduced. Note that, in the present embodiment, both the change in the exposure amount of the photosensitive member 4 due to the change in the scan speed, and the change in the exposure amount of the photosensitive member 4 caused by the change in the spot diameter of scan light on the photosensitive member 4 according to the image height are suppressed by correcting the tone value. However, a configuration can be adopted in which the change in the exposure amount of the photosensitive member 4 due to these two factors is suppressed by luminance correction. In this case, the density correction processing unit 101z can be omitted.
Next, a third embodiment will be described focusing on differences with the first embodiment. In the present embodiment, a toner projection development method is used as the development method. An imaging lens 406 of an optical scanning apparatus 400 according to the present embodiment has fθ characteristics. That is, the spot moves at a uniform speed on the scan surface 407 when the deflector 405 is rotated at a uniform angular velocity. Therefore, in the present embodiment, partial magnification correction and luminance correction need not to be performed.
The toner T inside the storage container 206 is drawn toward the developing sleeve 203 by a magnetic force of a magnet roller (unshown) inside the developing sleeve 203 and is held thereon. The toner T held on the developing sleeve 203 is carried to the restricting blade 204, charged by the restricting blade 204 rubbing against the developing sleeve 203, and is held on the developing sleeve 203. Distance restricting members 209 are provided at both end portions of the developing sleeve 203 in order to keep the distance uniform between the developing sleeve 203 and the photosensitive member 4 at a predetermined distance. A developing bias is applied in a region in which the developing sleeve 203 approaches the photosensitive member 4 by a high-voltage power supply that is not illustrated, and the latent image on the photosensitive member 4 is developed with the toner T on the developing sleeve 203. Also, the developing unit 208 is rotatable about a coupling member 210. The developing sleeve 203 is configured to be pressed toward the photosensitive member 4 with the distance restricting member 209 being interposed therebetween by a biasing member that is not illustrated and the weight of the developing unit 208.
In the present embodiment as well, one scan line is divided into seven regions along the main scanning direction, and correction amounts are assigned to the respective regions, similarly to the first embodiment. With this, the change in density caused by the fact that the distance between the developing sleeve 203 and the photosensitive member 4 is not uniform in the main scanning direction is corrected.
As described above, the optical scanning apparatus 400, in the present embodiment, is configured to scan the photosensitive member 4 at a fixed speed regardless of the image height. Meanwhile, the developing unit 208 is configured such that the developing sleeve 203 does not come into contact with the photosensitive member 4. In this configuration, nonuniformity in distance between the developing sleeve 203 and the photosensitive member 4 in the main scanning direction may occur, as described above. Also, a change in density in the main scanning direction due to this nonuniformity may occur. Therefore, density correction information is created and stored in the ROM 101 in advance in order to suppress this change in density. Then, the density correction processing unit 101z corrects the tone values based on the density correction information. According to this configuration, the change in density in the main scanning direction due to the configuration of the developing unit 208 can be reduced. Note that, in the present embodiment as well, a configuration can be adopted in which the change in density in the main scanning direction caused by the nonuniformity in distance between the developing sleeve 203 and the photosensitive member 4 in the main scanning direction is suppressed by performing luminance correction. In this case, the density correction processing unit 101z can be omitted.
Note that the present embodiment can be combined with the first embodiment or the second embodiment. That is, the present embodiment can also be applied to a case where the optical scanning apparatus 400 that does not have fθ characteristics is used. For example, in a configuration in which the present embodiment is combined with the first embodiment, density correction information is created such that the change in density, which is a combination of the change in density in the main scanning direction caused by the change in the spot diameter of scan light due to the image height and the change in density in the main scanning direction due to the nonuniformity in distance between the developing sleeve 203 and the photosensitive member 4 in the main scanning direction, is suppressed, and the density correction information is stored in the ROM 101 in advance. Also, in a configuration in which the present embodiment is combined with the second embodiment, density connection information is created in which the change in density in the main scanning direction caused by the change in the exposure amount in the main scanning direction is also considered, and the density correction information is stored in the ROM 101 in advance. In the case where only luminance correction is performed, a similar idea can also be applied.
Next, a fourth embodiment will be described focusing on differences with the first embodiment. There are cases where the developing unit 208 does not have uniform developing characteristics in the main scanning direction due to several factors, regardless of the method of development. For example, the flowability of toner is likely to decrease on an end portion side in the main scanning direction in the storage container 208 relative to that in a central portion, and the density on the end portion in the main scanning direction may decrease relative to that in the central portion. In the first embodiment, density correction is performed in addition to partial magnification connection and luminance correction for compensating nonuniformity due to the configuration (characteristics) of the optical scanning apparatus 400 and the exposure control characteristics when the optical scanning apparatus 400 is used. In the present embodiment, nonuniformity in density due to the configuration of the developing unit is also corrected in this density correction. In this case, characteristics (first embodiment) in which the density increases in end portions in the main scanning direction and characteristics in which the density increases in a central portion in the main scanning direction are combined to have complex characteristics. However, density correction information can be set in accordance with the characteristics.
Note that, in the present embodiment, the density correction processing unit 101z corrects the change in density in which the change in density in the main scanning direction described in the first embodiment and the change in density in the main scanning direction due to the configuration of the developing unit are combined. However, a configuration may also be adopted in which the density correction processing unit 101z corrects the change in density in which the change in density in the main scanning direction described in the second embodiment and the change in density in the main scanning direction due to the configuration of the developing unit are combined. Furthermore, if the developing unit 208 is a toner projection development type described in the third embodiment, for example, a configuration may be adopted in which the density correction processing unit 101z corrects the change in density in which the change in density caused by the change in distance between the developing sleeve 203 and the photosensitive member 4 and the change in density caused by another factor of the configuration of the developing unit 208 are combined. Note that the change in density caused by another factor of the configuration of the developing unit 208 is a change in density caused by the change in flowability of toner inside the storage container 206 in the main scanning direction, for example. Furthermore, in the present embodiment as well, the change in density in the main scanning direction can be suppressed by performing luminance correction instead of tone correction performed by the density correction processing unit 101z.
Next, a fifth embodiment will be described focusing on differences with the third embodiment. In the present embodiment, the density correction information to be used is switched according to the usage status of the developing unit 208. As shown in
In the present embodiment, a plurality of pieces of density correction information are stored in the ROM 102, and the density correction information to be used is selected according to the remaining toner amount. Two pieces of density correction information, namely first density correction information to be used when the remaining toner amount is 25% or more and second density correction information to be used when the remaining toner amount is less than 25%, are used as an example. When the remaining toner amount is 25% or more, the first density correction information that has been described using
Next, a sixth embodiment will be described focusing on differences with the fifth embodiment. In the present embodiment, a developing unit is configured to use a contact development method using non-magnetic one-component toner as the developer. In the contact development method as well, the density changes in the main scanning direction. This is because toner particles at end portions are likely to be more charged due to friction than toner particles in a central portion. As a result, the image density is likely to decrease in the end portions relative to that in the central portion in the main scanning direction.
Furthermore, in the contact development method, the difference in density in the main scanning direction changes in accordance with usage state of the developing unit. In the contact development method, the developing sleeve 203 is brought into contact with the photosensitive member 4, and the rotating speed of the developing sleeve 203 differs from that of the photosensitive member 4. Therefore, the surface layer of the photosensitive member 4 is scraped away when used. Here, the photosensitive member 4 is made of a thin film aluminum material as the base material, and slightly flexes, and therefore the photosensitive member 4 is scraped more at end portions in the main scanning direction than at a central portion. Electrostatic capacitance increases in a portion of the photosensitive member 4 that is more scraped away, and the absolute value of the charged potential when charged by the charging unit increases (in the example, the charged potential takes a negative value). When the charged potential increases, the absolute value of the exposure potential also increases (in the present embodiment, the exposure potential takes a negative value). As a result, the contrast against the developing potential decreases at the scraped portion, and the image density decreases.
That is, in the developing unit using the contact development method, the image density at end portions in the main scanning direction decreases relative to that at a central portion, as the rotation time of the developing sleeve 203 and the photosensitive member 4 increases. Therefore, in the present embodiment, the density correction conditions are set such that the image density is to be uniform in the main scanning direction while considering a change in developing characteristics in accordance with the rotation time of the developing sleeve 203. Specifically, a first density correction condition that is used until the accumulated rotation time of the developing sleeve 203 reaches a predetermined time and a second density correction condition that is used when the accumulated rotation time of the developing sleeve 203 exceeds the predetermined time are determined in advance. The second density correction condition is set such that the corrected tone value at the central portion is smaller than that in the first density correction condition. Note that a configuration may be adopted in which a plurality of threshold values of the accumulated rotation time are provided, and one density correction condition selected from the three or more density correction conditions in accordance with the accumulated rotation time is used.
Next, a seventh embodiment will be described focusing on differences with the sixth embodiment. As described in the sixth embodiment, in a developing unit using the contact development method, the amount of charges generated through friction of toner particles is larger at end portions than at a central portion, and therefore, the image density is more likely to decrease at the end portions than at the central portion. This is because toner particles near end portions of the developing sleeve 203 flow slower than those on a central side, in the storage container 206. Here, the flowability of toner particles has temperature characteristics. Specifically, the flowability of toner particles decreases when the ambient environment in which the image forming apparatus is used is a high temperature environment, or when the temperature inside the machine increases when the image forming apparatus is continuously used. As a result, the image density at the end portions decreases relative to that at the central portion.
Therefore, in the present embodiment, the density correction condition is set such that the image density of a printed item is to be uniform in the main scanning direction while considering the usage temperature of toner. For example, if the detected temperature of a temperature and humidity sensor exceeds 27 degrees, the density correction condition is switched so as to decrease the image density at the central portion. Also, a configuration may be adopted, by combining the sixth embodiment and the seventh embodiment, in which the density correction condition to be used is selected from a plurality of density correction conditions based on the temperature and the accumulated rotation time.
Various embodiments of the present invention have been described using a monochrome image forming apparatus. However, the present invention can be applied to intermediate transfer type and tandem transfer type color image forming apparatuses.
Also, in the first embodiment, the potential difference of the photosensitive member 4 due to the difference in the spot diameter is suppressed by performing both luminance correction and density correction. Here, the change in the spot diameter depends on the configuration of the optical scanning apparatus 400, and the spot diameter does not necessarily take a maximum value at end portions in the main scanning direction.
Also, the third embodiment has been described using the developing unit 208 that uses a toner projection development method. However, similar effects are obtained in a similar development method such as contact development, and the present embodiment can be applied to a developing unit that uses such a development method. Also, in the embodiments described above, the scan line is divided into seven regions along the main scanning direction, and the density correction information shows correction amounts of tone values in the respective regions. However, the number of divided regions is not limited to seven, and may be any number of two or more. Note that any combination of the embodiments described above is possible.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as anon-transitory computer-readable storage medium') to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2018-006690, filed on Jan. 18, 2018, which is hereby incorporated by reference herein in its entirety.
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| Number | Date | Country | |
|---|---|---|---|
| 20200241439 A1 | Jul 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16245558 | Jan 2019 | US |
| Child | 16847849 | US |
