Image forming apparatus and image processing apparatus

Abstract

To provide an image formation device and an image processing device which can reduce image failures caused by commonalization of a power source in an integrated circuit.SOLUTION: An image formation device includes an integrated circuit part having a first image processing part and a second image processing part operated by a common power source, and a control part for controlling the integrated circuit part and forming an image, wherein the first image processing part subjects continuous image data in a main scan direction to image processing on the basis of a first period, the second image processing part subjects the image data after the image processing by the first image processing part to image processing on the basis of a second period, and the control part changes a relation between a first period and a second period from setting, on the basis of a degree of image failures after the image processing by the second image processing part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and an image processing apparatus. [Background Art]

[0002] Generally, image forming apparatuses are known that include an integrated circuit such as an ASIC (application specific integrated circuit) as an internal processing circuit (see, for example, Patent Document 1). In recent years, along with the progress of miniaturization in semiconductor processes, the degree of integration of integrated circuits has increased, making it possible to integrate a circuit that was conventionally configured by a plurality of integrated circuits into a single integrated circuit.

[0003] Furthermore, due to circuit integration, it is necessary to supply a wide variety of power supply voltages such as core power supplies and IO power supplies for each function. Considering power noise interference, it is desirable to provide a dedicated power supply IC for each circuit. However, from the viewpoints of increasing the circuit scale of integrated circuits, reducing costs, and reducing the number of components on a substrate, it is generally known to share a power supply among a plurality of circuits.

[0004] For example, in an image forming apparatus, an integrated circuit that performs image processing is provided with two image processing units: one that performs all-color collective image processing and one that performs single-color independent image processing. Since the two image processing units have the same power supply voltage, the power supply for the two image processing units is shared in the integrated circuit. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2022-64626 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] However, in the integrated circuits described above, due to the shared power supply, power supply noise from one image processing unit could potentially affect the output of the other image processing unit, potentially leading to image defects.

[0007] The objective of the present invention is to provide an image forming apparatus and an image processing apparatus that can reduce image defects caused by the common use of power supplies in integrated circuits. [Means for solving the problem]

[0008] The image forming apparatus according to the present invention is An integrated circuit unit having a first image processing unit and a second image processing unit that operate on a common power supply, A control unit that controls the integrated circuit unit to form an image, Equipped with, The first image processing unit performs image processing on image data that is continuous in the main scanning direction based on the first period. The second image processing unit performs image processing on the image data after image processing by the first image processing unit based on the second cycle. The control unit after image processing by the second image processing unit , a discrepancy in the output value of the output image relative to the ideal image corresponding to the image data, which occurs due to the synchronization relationship between the first period and the second period. Based on the first period and the second period, To adjust the synchronization interval, one of the first period and the second period is changed from the setting value corresponding to the one. .

[0009] The image processing apparatus according to the present invention is An integrated circuit unit having a first image processing unit and a second image processing unit that operate on a common power supply, A control unit that controls the integrated circuit unit to form an image, Equipped with, The first image processing unit performs image processing on image data that is continuous in the main scanning direction based on the first period. The second image processing unit performs image processing on the image data after image processing by the first image processing unit based on the second cycle. The control unit after image processing by the second image processing unit , a discrepancy in the output value of the output image relative to the ideal image corresponding to the image data, which occurs due to the synchronization relationship between the first period and the second period. Based on the first period and the second period, To adjust the synchronization interval, one of the first period and the second period is changed from the setting value corresponding to the one. . [Effects of the Invention]

[0010] According to the present invention, image defects caused by shared power supply in an integrated circuit can be reduced. [Brief Description of the Drawings]

[0011] [Figure 1] FIG. 1 is a diagram schematically showing an overall configuration of an image forming system including an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing main parts of a control system of the image forming apparatus. [Figure 3] FIG. 3 is a block diagram showing each part of an image processing unit. [Figure 4] FIG. 4 is a time chart of a synchronization signal, a valid signal, a power supply voltage, and a PWM signal. [Figure 5] FIG. 5 is a time chart of a synchronization signal, a valid signal, a power supply voltage, and a PWM signal during enlargement processing. [Figure 6] FIG. 6 is a diagram showing an example of an image defect during enlargement processing. [Figure 7] FIG. 7 is a diagram showing the relationship between an interval at which a first cycle and a second cycle are synchronized and experimentally calculated visual sensitivity. [Figure 8] FIG. 8 is a time chart of the synchronization signal after adjusting the interval at which the first cycle and the second cycle are synchronized. [Mode for Carrying Out the Invention]

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing an overall configuration of an image forming system 100 including an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is a diagram showing main parts of a control system of the image forming apparatus 1.

[0013] As shown in FIG. 1, the image forming system 100 is configured by connecting the image forming apparatus 1 and a post-processing apparatus 2 from the upstream side along the conveyance direction of a sheet (recording medium) S.

[0014] The image forming apparatus 1 is an intermediate transfer type color image forming apparatus that uses electrophotographic process technology. Specifically, the image forming apparatus 1 primarily transfers each color toner image of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photoconductive drum 413 onto an intermediate transfer belt 421, superimposes the four color toner images on the intermediate transfer belt 421, and then secondarily transfers the superimposed toner images onto the sheet S fed from the paper feed tray units 51a to 51c, thereby forming an image.

[0015] Furthermore, the image forming apparatus 1 employs a tandem system in which photoconductive drums 413 corresponding to the four colors of YMCK are arranged in series in the traveling direction of the intermediate transfer belt 421, and each color toner image is sequentially transferred onto the intermediate transfer belt 421 in a single procedure.

[0016] As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a sheet conveying unit 50, a fixing unit 60, and a control unit 101.

[0017] The control unit 101 includes a CPU (Central Processing Unit) 102, a ROM (Read Only Memory) 103, a RAM (Random Access Memory) 104, and the like. The CPU 102 reads out a program corresponding to processing content from the ROM 103, loads the program into the RAM 104, and performs centralized control on the operations of each block and the like of the image forming apparatus 1 in cooperation with the loaded program. At this time, various data stored in the storage unit 72 is referred to. The storage unit 72 is configured of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

[0018] The control unit 101 transmits and receives various types of data to and from external devices (e.g., personal computers) connected to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network) via the communication unit 71. For example, the control unit 101 receives image data (input image data) transmitted from an external device and forms an image on the paper S based on this image data. The communication unit 71 is composed of a communication control card, such as a LAN card.

[0019] As shown in Figure 1, the image reading unit 10 is configured to include an automatic document feeder 11 called an ADF (Auto Document Feeder) and a document image scanning device 12 (scanner), etc.

[0020] The automatic document feeder 11 transports the documents D placed in the document tray using a transport mechanism and sends them to the document image scanner 12. The automatic document feeder 11 makes it possible to continuously scan images (including both sides) of multiple documents D placed in the document tray all at once.

[0021] The document image scanning device 12 optically scans a document transported from the automatic document feeder 11 onto the contact glass or a document placed on the contact glass, and images the reflected light from the document onto the light-receiving surface of the CCD (Charge Coupled Device) sensor 12a to read the document image. The image reading unit 10 generates input image data based on the reading result by the document image scanning device 12. This input image data is subjected to predetermined image processing by the image processing unit 30.

[0022] As shown in Figure 2, the operation display unit 20 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image status, and the operating status of each function in accordance with the display control signals input from the control unit 101. The operation unit 22 is equipped with various operation keys such as a numeric keypad and a start key, and accepts various input operations from the user and outputs operation signals to the control unit 101.

[0023] The image processing unit 30 includes circuits and other components that perform digital image processing according to initial settings or user settings. For example, under the control of the control unit 101, the image processing unit 30 performs gradation correction based on gradation correction data (gradation correction table). In addition to gradation correction, the image processing unit 30 also performs various correction processes such as color correction and shading correction, as well as compression processing. The image forming unit 40 is controlled based on the image data that has undergone these processes. Details of the image processing unit 30 will be described later.

[0024] As shown in Figure 1, the image forming unit 40 forms an image on the paper S based on the print job settings. The image forming unit 40 includes image forming units 41Y, 41M, 41C, 41K, an intermediate transfer unit 42, etc., for forming an image using colored toners of Y, M, C, and K components based on the input image data.

[0025] The image forming units 41Y, 41M, 41C, and 41K for the Y, M, C, and K components have similar configurations. For the sake of illustration and explanation, common components are indicated by the same reference numeral, and when distinguishing between them, Y, M, C, or K is added to the reference numeral. In Figure 1, only the components of the image forming unit 41Y for the Y component are labeled with reference numerals, while the components of the other image forming units 41M, 41C, and 41K are omitted.

[0026] The image forming unit 41 includes an exposure device 411, a developing device 412, a photoreceptor drum 413, a charging device 414, and a drum cleaning device 415, etc.

[0027] The photoreceptor drum 413 is, for example, an organic photoreceptor in which a photosensitive layer made of a resin containing an organic photoconductor is formed on the outer surface of a drum-shaped metal substrate.

[0028] The control unit 101 rotates the photoreceptor drum 413 at a constant peripheral speed by controlling the drive current supplied to the drive motor (not shown) that rotates the photoreceptor drum 413.

[0029] The charging device 414 is, for example, a charging charger, which uniformly charges the surface of the photoconductive photoreceptor drum 413 to a negative polarity by generating a corona discharge.

[0030] The exposure apparatus 411 is composed of, for example, a semiconductor laser, and irradiates the photoreceptor drum 413 with laser light corresponding to the image of each color component. As a result, electrostatic latent images of each color component are formed in the image region of the surface of the photoreceptor drum 413 that has been irradiated with laser light, due to the potential difference with the background region.

[0031] The developing device 412 is a two-component inverted type developing device that visualizes the electrostatic latent image by depositing developer for each color component onto the surface of the photoreceptor drum 413, thereby forming a toner image.

[0032] The developing device 412 is subjected to, for example, a DC developing bias with the same polarity as the charging polarity of the charging device 414, or a developing bias in which an AC voltage is superimposed with a DC voltage with the same polarity as the charging polarity of the charging device 414. As a result, inversion developing is performed, which causes toner to adhere to the electrostatic latent image formed by the exposure device 411.

[0033] The drum cleaning device 415 is in contact with the surface of the photoreceptor drum 413 and has a flat drum cleaning blade made of an elastic material, etc., and removes toner that remains on the surface of the photoreceptor drum 413 without being transferred to the intermediate transfer belt 421.

[0034] The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, and a belt cleaning device 426, etc.

[0035] The intermediate transfer belt 421 is an endless belt and is stretched in a loop around a plurality of support rollers 423. At least one of the plurality of support rollers 423 is a drive roller, and the others are driven rollers. For example, it is preferable that the roller 423A, which is located downstream in the belt travel direction from the primary transfer roller 422 for component K, is the drive roller. This makes it easier to maintain a constant belt travel speed in the primary transfer section. As the drive roller 423A rotates, the intermediate transfer belt 421 travels at a constant speed in the direction of arrow A.

[0036] The intermediate transfer belt 421 is a conductive and elastic belt with a high-resistance layer on its surface. The intermediate transfer belt 421 is rotationally driven by a control signal from the control unit 101.

[0037] The primary transfer roller 422 is positioned on the inner circumferential side of the intermediate transfer belt 421, facing the photoreceptor drum 413 for each color component. By pressing the primary transfer roller 422 against the photoreceptor drum 413 with the intermediate transfer belt 421 in between, a primary transfer nip is formed for transferring the toner image from the photoreceptor drum 413 to the intermediate transfer belt 421.

[0038] The secondary transfer roller 424 is positioned on the outer circumferential surface side of the intermediate transfer belt 421, opposite the backup roller 423B which is located downstream of the drive roller 423A in the belt travel direction. By pressing the secondary transfer roller 424 against the backup roller 423B with the intermediate transfer belt 421 in between, a secondary transfer nip is formed for transferring the toner image from the intermediate transfer belt 421 to the paper S.

[0039] As the intermediate transfer belt 421 passes over the primary transfer nip, the toner image on the photoreceptor drum 413 is sequentially superimposed onto the intermediate transfer belt 421 and primary transferred. Specifically, by applying a primary transfer bias to the primary transfer roller 422 and applying a charge with the opposite polarity to the toner to the back side of the intermediate transfer belt 421, that is, the side in contact with the primary transfer roller 422, the toner image is electrostatically transferred to the intermediate transfer belt 421.

[0040] Subsequently, as the paper S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is transferred to the paper S. Specifically, a secondary transfer bias is applied to the secondary transfer roller 424, and a charge with the opposite polarity to the toner is applied to the back side of the paper S, that is, the side in contact with the secondary transfer roller 424, thereby electrostatically transferring the toner image to the paper S. The paper S, on which the toner image has been transferred, is then transported toward the fuser unit 60.

[0041] The belt cleaning device 426 removes any remaining transfer toner from the surface of the intermediate transfer belt 421 after secondary transfer.

[0042] The fuser unit 60 includes an upper fuser unit 60A having a fuser surface-side member positioned on the fuser surface of the paper S, i.e., the side on which the toner image is formed; a lower fuser unit 60B having a back-side support member positioned on the back surface of the paper S, i.e., the side opposite the fuser surface; and a heating source, etc. When the back-side support member is pressed against the fuser surface-side member, a fuser nip is formed that grips and transports the paper S.

[0043] The fuser unit 60 heats and pressurizes the paper S, which has been transported after the toner image has been transferred to it, using a fuser nip, thereby fixing the toner image to the paper S. The fuser unit 60 is arranged as a unit within the fuser unit F.

[0044] The upper fixing section 60A has an endless fixing belt 61, a heating roller 62, and a fixing roller 63, which are fixing surface side members. The fixing belt 61 is stretched by the heating roller 62 and the fixing roller 63.

[0045] The lower fixing section 60B has a pressure roller 64, which is a support member on the back side. The pressure roller 64 forms a fixing nip that grips and transports the paper S between itself and the fixing belt 61.

[0046] The paper transport unit 50 includes a paper feeding unit 51, a paper discharge unit 52, and a transport path unit 53, etc. The three paper feeding tray units 51a to 51c that make up the paper feeding unit 51 store paper S (standard paper, special paper) identified based on basis weight, size, etc., according to pre-set types.

[0047] The transport path section 53 includes a plurality of transport roller pairs such as registration roller pairs 53a, and a normal transport path 53b that allows the paper S to pass through the image forming section 40 and the fixing section 60 and be discharged outside the image forming apparatus 1.

[0048] The paper sheets S stored in the paper feed tray units 51a to 51c are fed out one sheet at a time from the top and transported to the image forming unit 40 by the transport path unit 53. In the image forming unit 40, the toner image from the intermediate transfer belt 421 is transferred to one side of the paper sheet S all at once, and a fixing process is performed in the fixing unit 60. The image formed paper sheet S is then discharged from the machine by the paper discharge unit 52 equipped with a paper discharge roller 52a.

[0049] The post-processing device 2 receives the paper S ejected from the image forming apparatus 1 and includes a reader 200 capable of reading the image on the paper S after the image has been formed. The reader 200 feeds back the read data to the image forming apparatus 1. After the image has been read by the reader 200, the post-processing device 2 ejects the paper S from the machine. The post-processing device 2 (reader 200) may also have a control unit equipped with a CPU, ROM, RAM, etc., and this control unit may perform control related to the transport of the paper S and image reading within the post-processing device 2, separately from the control unit 101 of the image forming apparatus 1.

[0050] Next, the details of the image processing unit 30 will be described. Figure 3 is a block diagram showing the various parts of the image processing unit 30.

[0051] As shown in Figure 3, the image processing unit 30 is an integrated circuit unit composed of an ASIC, and includes a power supply unit 31, a storage unit 32, a first image processing unit 33, and a second image processing unit 34.

[0052] The power supply unit 31 is the part that receives power from a power supply IC provided in the image forming apparatus 1, and has a first power supply 31A, a second power supply 31B, and a third power supply 31C.

[0053] The first power supply 31A is a power supply that supplies power to the terminals of the integrated circuit and is connected to a power supply IC capable of supplying a first voltage value (for example, 3.3V).

[0054] The second power supply 31B is a power supply that supplies power to the memory unit 32 and is connected to a power supply IC that can supply a second voltage value different from the first voltage value (for example, 1.8V or 1.1V).

[0055] The third power supply 31C is a power supply that supplies power to both the first image processing unit 33 and the second image processing unit 34, and is connected to a power supply IC capable of supplying a third voltage value (e.g., 0.9V) that is different from the first and second voltage values.

[0056] The storage unit 32 temporarily stores the image data input from the control unit 101 or the reader 200, and the image data processed by the first image processing unit 33. The storage unit 32 outputs the temporarily stored image data to the first image processing unit 33 or the second image processing unit 34.

[0057] The first image processing unit 33 performs image processing on image data that is continuous in the main scanning direction based on the first cycle. The image processing performed by the first image processing unit 33 is a process that is performed on all YMCK colors at once, and includes, for example, a process to convert color values ​​from RGB values ​​to YMCK values, a color conversion process, a resolution conversion process, and a scaling process.

[0058] In the first image processing unit 33, image processing is performed within the first cycle on multiple lines of image data that are continuous in the main scanning direction in the image data (image data input from the control unit 101) that are temporarily stored in the memory unit 32.

[0059] Image processing by the first image processing unit 33 is performed within a predetermined valid period within the first cycle, and the image data after image processing is output to the storage unit 32 and temporarily stored.

[0060] The first cycle is set to a time (first setting value) during which the first image processing unit 33 can perform image processing. For example, the control unit 101, etc., outputs a first synchronization signal in the first cycle (see Figure 4), and after the first synchronization signal is output and before the next first synchronization signal is output, the first image processing unit 33 performs image processing on the image data of the multiple lines mentioned above.

[0061] The predetermined valid period is, for example, the period during which the valid signal, which consists of the pulse signal of the first period, is low (low period). The valid signal is a signal used by the first image processing unit 33 to recognize whether or not to perform image processing. The first image processing unit 33 performs image processing by recognizing the low period of the valid signal.

[0062] Furthermore, when image processing is performed by the first image processing unit 33, a voltage drop in the power supply voltage occurs due to the load incurred by the image processing. For example, since image processing is performed during the validity period of the valid signal, the amount of voltage drop in the power supply voltage is largest during the validity period.

[0063] The second image processing unit 34 performs image processing on the image data after image processing by the first image processing unit 33 based on the second cycle. The image processing performed by the second image processing unit 34 is performed for each color of YMCK, and includes, for example, gradation (gamma) adjustment, multi-beam image division, output timing adjustment, and PWM (pulse width modulate) conversion. The second image processing unit 34 includes an analog circuit for PWM conversion.

[0064] Image processing by the second image processing unit 34 is performed in parallel with the image processing of the first image processing unit 33, using a pipeline method, after acquiring the image data processed by the first image processing unit 33 from the storage unit 32.

[0065] The second image processing unit 34 outputs the image data after image processing to the image forming unit 40 using the PWM conversion described above. Since the exposure apparatus 411 of the image forming unit 40 has multiple light sources and is configured to emit multiple beams, the second image processing unit 34 outputs a PWM signal to cause the multiple beams to emit light.

[0066] In the image forming apparatus 1, the image forming unit 40 operates in accordance with the transport speed of the paper S. Therefore, the second cycle becomes the reference for image handling, and the first setting value of the first cycle is determined by the setting value of the second cycle (second setting value).

[0067] Specifically, the second period is set to a second setting value that is longer than the first setting value of the first period. For example, the first setting value is set to 1 / n times the second setting value (where n is an integer greater than 1).

[0068] For example, when the exposure apparatus 411 of the image forming unit 40 performs an 8-beam writing operation, the first image processing unit 33 processes the image data of 4 lines, which is half of the total. In this case, the first setting value for the first cycle is set to half the second setting value for the second cycle. In the following, it will be assumed that the first setting value for the first cycle is set to half the second setting value for the second cycle.

[0069] For example, the control unit 101 outputs a second synchronization signal in synchronization with an arbitrary first synchronization signal during the second cycle. After the second synchronization signal is output, image processing is performed by the second image processing unit 34 until the next second synchronization signal is output. In other words, the PWM signal is output from the second image processing unit 34 for a period equivalent to two first cycles. The PWM signal is a signal that indicates the value of the image data, but in Figure 4, etc., it is shown as a constant value for the sake of clarity.

[0070] Furthermore, when the first image processing unit 33 performs an enlargement process, the processing time by the first image processing unit 33 increases, making it necessary to adjust the timing of the storage processing in the storage unit 32. Therefore, in order to ensure sufficient waiting time for this processing, the second cycle is extended beyond the second setting value. In other words, when the first image processing unit 33 performs an enlargement process, the control unit 101 extends the second cycle beyond the second setting value.

[0071] In normal processing, the second synchronization signal is always synchronized with the first synchronization signal. However, by extending the second period, a second synchronization signal exists that is asynchronous with the first synchronization signal.

[0072] For example, as shown in Figure 5, if the second period is extended by 2% from the second setpoint, after the first and second synchronization signals synchronize, the second synchronization signal will lag behind the first synchronization signal by the amount of the 2% extension.

[0073] When the second cycle is extended by 2% from the second setpoint, the timing at which the first and second synchronization signals synchronize again after the initial synchronization will be 25 cycles later, which is a total delay of 50%. The degree to which the second cycle is extended can be set as appropriate.

[0074] Incidentally, when expansion processing is performed, the voltage drop of the power supply voltage increases due to the increased processing load during the effective period, and consequently, the power supply noise also increases. Therefore, the PWM signal may not reach the desired value due to the increased voltage drop and power supply noise.

[0075] Because the power supply for the first image processing unit 33 and the second image processing unit 34 is shared, voltage drops and power supply noise caused by processing in the first image processing unit 33 may leak into the second image processing unit 34 and affect its processing.

[0076] In the case of digital circuits, power supply voltage drop has little impact on operation because processing is based on the maximum and minimum voltages (0V). However, in the case of analog circuits, fluctuations in power supply voltage can cause significant deviations in output values.

[0077] Since the PWM signal in the second image processing unit 34 is an output from an analog circuit, as described above, the output value tends to deviate significantly due to the increase in the voltage drop of the power supply voltage and the increase in power supply noise, and is therefore greatly affected by power supply noise.

[0078] For example, as shown in Figure 5, the PWM signal has different values ​​during the low period (effective period) of the active signal and during other periods. In each second period, because the second period is extended, the first and second synchronization signals become asynchronous, causing a shift in the period during which the PWM signal is generated and the effective period overlap.

[0079] Therefore, the shape of the PWM signal differs for each period. Specifically, the portion of the PWM signal corresponding to the high period of the active signal is more recessed than the portion corresponding to the low period, and the time positions of the recessed portion differ for each period due to the extension of the second period.

[0080] For example, when outputting an image with full halftone, the image will have diagonal streaks, as shown in Figure 6. If the second cycle is extended by 2% from the second setting value, the width corresponding to 25 second cycles (e.g., 2.16 mm) will be the size of the diagonal streaks.

[0081] Therefore, in this embodiment, in order to reduce the above-mentioned image defects, the control unit 101 changes the relationship between the first cycle and the second cycle from the setting based on the degree of image defects after image processing by the second image processing unit 34.

[0082] The degree of image defects is determined based on factors such as the size of the diagonal lines mentioned above, the deviation of the output value from the ideal image, the user's visual judgment, and the synchronization interval between the first and second cycles. In this embodiment, the degree of image defects is defined as the visible sensitivity, which is an index indicating how easily the image defects are visible.

[0083] Figure 7 shows the relationship between the synchronization interval between the first and second periods and the experimentally calculated visible light sensitivity.

[0084] As shown in Figure 7, it has been experimentally confirmed that the visible light sensitivity increases as the synchronization interval between the first and second periods increases, and then gradually decreases after exceeding 1. For example, in the image shown in Figure 6, the visible light sensitivity at a synchronization interval of 2.16 mm between the first and second periods is slightly less than 1. Note that the visible light sensitivity shown in Figure 7 was calculated using an image analysis filter on the FFT analysis results of the image, but it may also be calculated by other methods.

[0085] For example, by narrowing the synchronization interval between the first and second cycles so that the visible sensitivity is below a predetermined value (e.g., 0.5), it is possible to make the diagonal streak image defects mentioned above less noticeable. In other words, if the degree of image defects is greater than a predetermined value, the control unit 101 changes the relationship between the first and second cycles from the settings so that the degree of image defects becomes below the predetermined value.

[0086] Specifically, when the control unit 101 performs an enlargement process, it reduces the first cycle to a smaller value than the first set value based on the degree of image defects after the enlargement of the second set value.

[0087] This adjusts the synchronization interval between the first and second cycles, making it possible to reduce the degree of image degradation (visible sensitivity).

[0088] For example, as shown in Figure 8, suppose the first period is made smaller than the first set value, and the interval at which the first period and the extended second period synchronize is set to five times the second period.

[0089] This allows us to reduce the width to one-fifth (0.432 mm) compared to, for example, the width corresponding to the second cycle of 25 cycles (e.g., 2.16 mm). As a result, the change in the relationship between the first and second cycles can be made so minor that it is imperceptible to the user visually, compared to before the change.

[0090] In other words, this embodiment makes it possible to reduce image defects caused by the common use of power supplies in integrated circuits.

[0091] Furthermore, the image formation result after image processing by the second image processing unit 34 may be fed back to the control unit 101. In other words, the control unit 101 estimates the degree of image defects based on the image formation result after image processing by the second image processing unit 34, and changes the relationship between the first cycle and the second cycle from the setting based on the estimated degree of image defects.

[0092] For example, the control unit 101 may determine that the image formation result may be, for example, the result of reading by the reading device 200.

[0093] The control unit 101 compares the reading result from the reading device 200 with the image data, calculates the width of the diagonal lines, and recognizes the interval at which the first and second cycles synchronize (for example, the width of the second cycle after 25 repetitions in Figure 6).

[0094] The control unit 101 estimates the visible sensitivity (degree of image defects) from the relationship shown in Figure 7, based on the interval at which the recognized first and second cycles synchronize. If the visible sensitivity is greater than a predetermined value, the control unit 101 changes the relationship between the first and second cycles from the settings so that the visible sensitivity becomes less than or equal to the predetermined value.

[0095] This allows for the determination of the degree of image defects based on the actual output image, thereby further reducing image defects caused by the commonality of power supplies in integrated circuits.

[0096] Alternatively, the degree of image defects can be estimated by performing an enlargement process.

[0097] When performing the magnification process, it is necessary to set the expansion amount of the second setting value of the second cycle. Therefore, it is possible to obtain data based on the expansion amount in advance through experiments, etc., and estimate the degree of image defects based on that data. In other words, the control unit 101 may estimate the degree of image defects based on the expansion amount of the second cycle and change the relationship between the first cycle and the second cycle based on the estimated degree of image defects.

[0098] In the above embodiment, the relationship between the first and second periods was changed during the enlargement process, that is, when the second period was extended, but the present invention is not limited to this. For example, if in normal processing there is a setting in the second synchronization signal that does not synchronize with the first synchronization signal, the relationship between the first and second periods may be changed to adjust the synchronization interval between the first and second periods in order to reduce the degree of image defects.

[0099] Furthermore, although the first period was set to a smaller value than the first set value in the above embodiment, the present invention is not limited to this. For example, if the setting is such that, in normal processing, there are second synchronization signals that do not synchronize with the first synchronization signal, the relationship between the first and second periods may be changed by reducing the second set value of the second period.

[0100] Furthermore, in the above embodiment, the degree of image defects was defined as visible sensitivity, and the relationship between the first and second cycles was changed based on this visible sensitivity. However, the present invention is not limited to this. For example, the degree of image defects may be defined as the size of diagonal lines, the deviation of the output value from the ideal image, or the synchronization interval between the first and second cycles. The threshold values ​​(predetermined values) for the size of diagonal lines, the deviation of the output value from the ideal image, or the synchronization interval between the first and second cycles may be set as appropriate.

[0101] Furthermore, although the image processing unit and the control unit were configured separately in the above embodiment, the present invention is not limited to this. For example, the control unit may be mounted on the image processing unit. In this case, the image processing unit may be a device other than an image forming apparatus (image processing device), such as a personal computer.

[0102] Furthermore, the above embodiments are merely examples of how the present invention may be implemented, and the technical scope of the present invention should not be limited by them. In other words, the present invention can be implemented in various ways without departing from its gist or its main features. [Explanation of Symbols]

[0103] 1. Image forming apparatus 2. Post-processing device 30 Image Processing Unit 31 Power supply section 31A 1st power supply 31B 2nd power supply 31C 3rd power supply 32 Storage section 33 First Image Processing Unit 34. Second Image Processing Unit 40 Image forming unit 100 Image Forming Systems 101 Control Unit

Claims

1. An integrated circuit unit having a first image processing unit and a second image processing unit that operate on a common power supply, A control unit that controls the integrated circuit unit to form an image, Equipped with, The first image processing unit performs image processing on image data that is continuous in the main scanning direction based on the first period. The second image processing unit performs image processing on the image data after image processing by the first image processing unit based on the second cycle. The control unit adjusts the synchronization interval between the first and second periods by changing one of them from a set value corresponding to the other, based on the discrepancy in the output value of the output image relative to the ideal image corresponding to the image data, which occurs due to the synchronization relationship between the first and second periods after image processing by the second image processing unit. Image forming apparatus.

2. If the deviation of the output value is greater than a predetermined value, the control unit changes the setting value corresponding to one of the above so that the deviation of the output value becomes less than or equal to the predetermined value. The image forming apparatus according to claim 1.

3. The second period is set to a second setting value that is longer than the first setting value of the first period. When the control unit performs an enlargement process in the first image processing unit, it changes the first period from the first set value. The image forming apparatus according to claim 1.

4. The control unit, When performing the expansion process, the second period is expanded beyond the second set value. Based on the deviation of the output value after the expansion of the second setting value, the first period is made smaller than the first setting value. The image forming apparatus according to claim 3.

5. The control unit estimates the deviation of the output value based on the image formation result after image processing by the second image processing unit, and changes one of the values ​​from the setting value corresponding to the one based on the estimated result of the deviation of the output value. The image forming apparatus according to claim 1.

6. An integrated circuit unit having a first image processing unit and a second image processing unit that operate on a common power supply, A control unit that controls the integrated circuit unit to form an image, Equipped with, The first image processing unit performs image processing on image data that is continuous in the main scanning direction based on the first period. The second image processing unit performs image processing on the image data after image processing by the first image processing unit based on the second cycle. The control unit adjusts the synchronization interval between the first and second periods by changing one of them from a set value corresponding to the other, based on the discrepancy in the output value of the output image relative to the ideal image corresponding to the image data, which occurs due to the synchronization relationship between the first and second periods after image processing by the second image processing unit. Image processing device.

Images