Printing system including static eliminator, control method and program thereof

Abstract

To provide an image formation device including a static eliminator which solves the problem that since in a region where a toner of a sheet printed with image data of a charged printing job is mounted, a toner layer behaves as a resistance, when an optimal application voltage value is not set according to a used amount of the toner and an area where the toner is mounted, a voltage value for static elimination may result in sticking the sheet.SOLUTION: An image formation device includes reception means for receiving a printing job from a client computer connected via network, printing means for executing printing processing on a sheet, on the basis of the content of the printing job, and a static eliminator for performing static elimination processing of the printed sheet, and has adjustment means for adjusting a voltage value applied to the sheet by the static eliminator, on the basis of a charge amount calculated from image data of the page of the printing job.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus including a static eliminator that eliminates static electricity from a charged recording medium, and a control method and program for the image forming apparatus. [Background technology]

[0002] Recording media (hereafter referred to as "sheets") used in printing work are transported in a statically charged state due to residual charge during the electrophotographic process or slight friction with transport rollers and guides that occurs during sheet transport. This static electricity can cause sheets to stick together. It can also cause dust and paper powder to adhere to the finished product, resulting in a decrease in the quality of the finished product. Plain paper has a low electrical resistance, so charges move easily within the paper, and the charge itself is small, so the charge dissipates quickly. Also, the toner layer on the sheet acts as a resistor, so the more toner used, the more likely it is to become charged and the more likely it is to retain a charge, even for the same type of sheet. Furthermore, in the case of double-sided printing, toner layers are formed on the front and back of the sheet, making it difficult for charges to move within the paper, and as a result, the more toner there is on the sheet, the more likely it is to become charged and the more likely it is to retain a charge.

[0003] If post-processing is performed while the sheets are stuck to each other, this not only affects the sheet alignment process and reduces the quality of the post-processing, but also may induce jams during post-processing. Therefore, in order to prevent such a risk from occurring, it is desirable to remove static electricity from the sheet after the printing process before performing post-processing. Therefore, a proposal has been made to apply a voltage to a pair of transport rollers located downstream in the sheet transport direction to cancel the charge on the sheet (Patent Document 1). In the case of removing static electricity using a configuration in which a voltage is applied to a transport roller (hereinafter referred to as a "discharging roller"), a charge opposite to the charge on the sheet is applied to the sheet via the discharging roller, thereby canceling the static electricity. Therefore, the discharging control using the discharging roller (applying a charge opposite to that of the sheet to the discharging roller) needs to be performed according to the amount of charge on the sheet. Furthermore, there is an optimal charge adjustment value for discharging for each printing environment such as humidity and each brand of sheet. If discharging control is performed on the sheet in an inappropriate charge adjustment state, it may cause charging on the contrary, which may lead to further sticking of the sheet. In the process of finding the optimum applied voltage value for static elimination (hereinafter referred to as the "adjustment process"), the optimum applied voltage value for static elimination is determined by setting and adjusting the applied voltage value for the sheet conveyed from the printing device by a static elimination device having a static elimination roller. The applied voltage value determined in the adjustment process is the optimum applied voltage value for the printing environment and sheet type used in the adjustment process. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-258881 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the area where the toner of the job actually input by the user is applied, the toner layer acts as a resistor, so the applied voltage value is not optimal according to the amount of toner used and the area where the toner is applied, which may lead to sheet sticking.In addition, although it is possible to use the job input by the user for the adjustment process, it is time-consuming because the adjustment process must be performed every time before inputting a job, and if the job is multiple pages, the optimal applied voltage value differs for each page, which may similarly lead to sheet sticking. An object of the present invention is to provide a mechanism for performing an appropriate charge removal process in accordance with the amount of toner used on each page of a print job. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention has the following configuration. The image forming apparatus includes a receiving means for receiving a print job from a client computer connected via a network, a printing means for executing a printing process on a sheet based on the contents of the print job, and a discharge device for performing a discharge process on the printed sheet, and is characterized in having an adjustment means for adjusting a voltage value applied to the sheet by the discharge device based on an amount of charge calculated from image data of a page of the print job. Effect of the Invention

[0007] According to the present invention, it is possible to carry out an appropriate charge removal process in accordance with the amount of toner used on each page. [Brief description of the drawings]

[0008] [Figure 1] Minimum system configuration diagram in this embodiment [Diagram 2] Hardware block diagram of the printing device [Diagram 3] Cross-sectional view of an image forming apparatus [Figure 4] FIG. 1 is a diagram of an operation unit provided in a printing device. [Diagram 5] Hardware block diagram of the static eliminator [Figure 6]FIG. 1 is a diagram of an operation unit provided in a static eliminator. [Figure 7] Schematic diagram of static elimination processing [Figure 8] Basic flow chart of the embodiment [Figure 9] Examples of print jobs supplementing the embodiment [Figure 10] Flowchart for determining toner usage coefficient according to an embodiment [Figure 11] Flowchart for determining the applied voltage value to be adjusted according to the embodiment [Figure 12] Supplementary print job examples of other embodiments [Figure 13] Flowchart for determining toner area factor according to another embodiment [Figure 14] Flowchart for determining the applied voltage value to be adjusted according to another embodiment [Figure 15] Examples of supplemental print jobs according to another embodiment [Figure 16] Basic flow chart of another embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the components described in the embodiment are merely examples, and are not intended to limit the scope of the present invention.

[0010] [Embodiment 1] Overall configuration 1 shows the simplest overall configuration of this embodiment, which includes an image forming apparatus 1000 and a client computer 102 (hereinafter referred to as "PC 102"), which are connected to each other via a network 101. The PC 102 is capable of transmitting PDL (page description language) code data, which is a print job, to the image forming apparatus 1000 via the network 101. Hardware configuration of image forming device Next, the image forming apparatus 1000 will be described with reference to the hardware block diagram of FIG. 2. The image forming apparatus 1000 includes a printing apparatus 100, which is enclosed by a dotted line in the figure, and a sheet processing apparatus 200. Any number of sheet processing apparatuses 200 can be connected to the printing apparatus 100. In addition, in this embodiment, the printing apparatus 100 will be described as an example of an MFP (Multi Function Peripheral) having multiple functions such as a copy function and a printer function. However, the printing apparatus 100 may be a single-function printing apparatus having only a copy function or only a printer function. In this embodiment, as an example, the image forming apparatus 1000 is assumed to have various components described below.

[0011] The image forming apparatus 1000 is configured so that sheet processing for sheets printed by the printing apparatus 100 can be performed by a sheet processing apparatus 200 connected to the printing apparatus 100. However, it is also possible to configure the image forming apparatus 1000 using only the printing apparatus 100 without connecting the sheet processing apparatus 200. The sheet processing apparatus 200 is configured to be able to communicate with the printing apparatus 100, and can receive instructions from the printing apparatus 100 and execute sheet processing as described below. A scanner unit 201 reads an image on a document, converts it into image data, and transfers it to other units. The external I / F 202 transmits and receives data to and from other devices connected to the network 101 . The printer unit 203 prints an image based on the input image data onto a sheet. 4, the operation unit 204 has a hard key input unit (key input unit) 402 and a touch panel unit 401, and receives instructions from a user via them. The operation unit 204 also displays various information on the touch panel unit 401 that the operation unit 204 has.

[0012] The control unit 205 is a CPU and generally controls the processing and operation of various units included in the image forming apparatus 1000. In other words, it also controls the operation of the printing apparatus 100 and the sheet processing apparatus 200 connected to the printing apparatus 100. The ROM 207 stores various computer programs executed by the control unit 205. For example, the ROM 207 stores a program for causing the control unit 205 to execute various processes of flowcharts described later, and a display control program required for displaying various setting screens described later. The ROM 207 also stores a program for the control unit 205 to interpret PDL code data received from the PC 102 and expand it into raster image data (image data). The ROM 207 also stores a boot sequence, font information, and the like. The RAM 208 stores image data and PDL code data sent from the scanner unit 201 and the external I / F 202, various programs loaded from the ROM 207, and setting information. The RAM 208 also stores information related to the sheet processing apparatus 200 (such as information related to the type and function of each sheet processing apparatus 200 connected to the printing apparatus 100). The control unit 205 can use the information related to the sheet processing apparatus 200 stored in the RAM 208 for control.

[0013] The HDD (hard disk drive) 209 is composed of a hard disk and a drive unit that reads and writes data to the hard disk. The HDD 209 is a large-capacity storage device for storing scanned image data input from the scanner unit 201 and compressed by the compression / decompression unit 210. The control unit 205, which is a CPU, can print image data stored in the HDD 209 by the printer unit 203 based on an instruction from a user. The HDD 209 is also used as a spooler, and the control unit 205 can manage PDL code data received from the PC 102 as a print job and store it in the HDD 209. The control unit 205, which is a CPU, can also manage print jobs stored in the HDD 209, and can also obtain the number of print jobs stored and setting information made for the print jobs. The compression / decompression unit 210 compresses and decompresses image data stored in the RAM 208 and HDD 209 using various compression methods such as JBIG and JPEG. The HDD 209 stores optimum applied voltage values ​​for each sheet type as sheet parameters in advance. These sheet parameters are values ​​written as defaults as recommended values ​​for each sheet type when the printing apparatus 100 is shipped from the factory. When the user turns on the static neutralization function and selects a sheet for printing, the applied voltage value set for the selected sheet type is read from the HDD 209 and reflected. When the control unit 205 receives the applied voltage value for the sheet determined in the adjustment process via the operation unit 204, it updates the sheet parameters corresponding to the sheet type and stores them in the HDD 209. As will be described later, the control unit 205 calculates the amount of toner used when printing on a sheet from the input image data and image data stored in the HDD 209. Then, the control unit 205 performs a process of further adjusting the applied voltage value stored in the HDD 209 in accordance with the amount of toner used, to obtain an optimal applied voltage value.

[0014] (Cross-sectional view of an image forming apparatus) Next, the configuration of the image forming apparatus 1000 will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view of the printing apparatus 100 and the sheet processing apparatus 200 connected to the printing apparatus 100. In this figure, the sheet processing apparatus is configured to include a static eliminator 200-3a and a saddle stitching machine 200-3b. First, the printing device 100 will be described. An automatic document feeder (ADF) 301 separates a stack of documents set on a loading surface of a document tray in page order, starting with the first page, and conveys the documents onto a document glass platen for scanning by a scanner 302 . The scanner 302 reads an image of a document conveyed onto a glass platen, and converts the image into image data by a CCD. A rotating polygon mirror (polygon mirror or the like) 303 causes a light beam, such as a laser beam, modulated according to image data to enter the rotating polygon mirror 303, and irradiates the light beam as reflected scanning light onto a photosensitive drum 304 via a reflecting mirror. A latent image formed on the photosensitive drum 304 by the laser beam is developed with toner, and the toner image is transferred to a sheet material attached on a transfer drum 305. A full-color image is formed by sequentially executing this series of image formation processes for yellow (Y), magenta (M), cyan (C), and black (K) toners. After four image formation processes, the sheet material on the transfer drum 305 on which the full-color image has been formed is separated by a separation claw 306 and conveyed to a fixing device 308 by a pre-fixing conveyor 307. The fixing device 308 is made up of a combination of rollers and belts, and has a built-in heat source such as a halogen heater, and melts and fixes the toner on the sheet material onto which the toner image has been transferred, by using heat and pressure. The discharge flapper 309 is configured to be swingable about a swing axis and determines the conveying direction of the sheet material. When the discharge flapper 309 swings in the clockwise direction in the figure, the sheet material is conveyed straight and is discharged outside the machine by the discharge rollers 310. The control unit 205 controls the printing device 100 to perform single-sided printing by the above-mentioned series of sequences.

[0015] On the other hand, when images are to be formed on both sides of the sheet material, the discharge flapper 309 swings counterclockwise in the figure, and the sheet material is changed course downward and sent to the double-sided conveying section. The double-sided conveying unit includes a reversing flapper 311, a reversing roller 312, a reversing guide 313, and a double-sided tray 314. The reversing flapper 311 swings around a swing axis to determine the conveying direction of the sheet material. When processing a double-sided print job, the control unit 205 controls the reversing flapper 311 to swing the sheet, whose first side has been printed by the printer unit 203, in a counterclockwise direction in the figure, and to feed the sheet to the reversing guide 313 via the reversing roller 312. Then, in a state where the rear end of the sheet material is sandwiched between the reversing roller 312, the reversing roller 312 is temporarily stopped, and the reversing flapper 311 continues to swing in a clockwise direction in the figure. Also, the reversing roller 312 is rotated in the reverse direction. As a result, the sheet is switched back and conveyed, and the sheet is controlled to be guided to the double-sided tray 314 with the rear end and the front end of the sheet switched. The sheet material is temporarily loaded in the double-sided tray 314, and then the sheet material is sent again to the registration rollers 316 by the re-feed rollers 315. At this time, the sheet material is sent with the side opposite to the transfer process of the first side facing the photosensitive drum. Then, in the same manner as the process described above, an image for the second side is formed on the second side of the sheet. Then, images are formed on both sides of the sheet material, and the sheet is discharged from inside the main body of the printer 100 to the outside of the machine via the discharge rollers 310 after a fixing process. The control unit 205 controls the printer 100 to perform double-sided printing through the above-mentioned series of sequences.

[0016] The printing device 100 also has a paper feed section that stores sheets required for printing processing. The paper feed section includes paper feed cassettes 317 and 318 (each capable of storing, for example, 500 sheets), a paper feed deck 319 (capable of storing, for example, 5,000 sheets), and a manual feed tray 320. The paper feed cassettes 317 and 318 and the paper feed deck 319 can be used to set various sheets of different sizes and materials separately for each paper feed section. Furthermore, the manual feed tray 320 can be used to set various sheets including special sheets such as overhead projector sheets.

[0017] (static eliminator) Next, the static eliminator 200-3a will be described. First, Fig. 5 is a hardware block diagram of the static eliminator 200-3a. The static eliminator also has a control unit 501 separate from the printing device 100, and this control unit 501 controls the entire static eliminator 200-3a while communicating with the control unit 205 of the printing device 100 in Fig. 2 via a bus (not shown). The operation unit 502 is configured as shown in FIG. 6, and the user can perform settings for the static elimination device 200-3a via the operation unit 502. The mode setting switch 601 in FIG. 6 switches whether or not static elimination is performed by the static elimination device 200-3a (ON / OFF), and the control unit 501 controls the static elimination processing unit 503 to execute the static elimination processing only when the switch is ON. The adjustment dial 602, which is configured as a thumb rotary switch, adjusts the strength of the static elimination control performed when the mode setting switch 601 is ON, and is controlled by the control unit 501 so as to be effective only when the mode setting switch 601 is ON. The adjustment dial 602 sets the voltage value applied from the voltage application controller 321 to the static elimination roller 322, and can set values ​​from "00" to "99". For example, setting "10" on the adjustment dial 602 indicates that the applied voltage value is set to +1.0 [kV]. In addition, when the maximum applied voltage of the static electricity removal roller is +6.0 [kV], even if the adjustment dial 602 is set to "61" to "99", the applied voltage value is fixed to +6.0 [kV], and it is not possible to set the applied voltage higher than that. In general, the optimal applied voltage value for the sheet used in that environment is adjusted and derived using the adjustment dial 602, and then the applied voltage value is set and printing is performed. A case will be described in which the charge amount of the sheet becomes 0 [kV] (static removal) by setting +6 [kV] as the applied voltage value for a sheet that is charged to -6 [kV] at the time of transfer by the adjustment process. First, the user sets the adjustment dial 602 to "60". Next, the voltage application controller 321 controls the static electricity removal roller 322 to be charged to +6 [kV], and performs static electricity removal processing on the conveyed sheet. In addition, since the optimal applied voltage value changes depending on the sheet characteristics and the environment in which the static electricity removal device 200-3a is used, when printing a sheet that is easily charged, it is desirable to start the printing process after deriving the applied voltage value by the adjustment process before printing. In this embodiment, the configuration of the operation unit 502 has been described as consisting of a physical mode setting switch and a thumb rotary switch, but it is also possible to use the touch panel section 401 of the operation unit 204 to perform display, OFF / ON, and change the applied voltage value on the UI.In this case, the control unit 205 of the printing device 100 communicates with the control unit 501 via a bus not shown, providing the information input to the operation unit 204, and the control unit 501, upon receiving this, provides the static elimination processing unit 503 with the information necessary for the static elimination processing described below.

[0018] The static elimination processing unit 503 is composed of a static elimination roller 322 and an ionizer 323, which will be described later, and a voltage application controller 321 for each of them, and is responsible for eliminating static electricity from the conveyed sheet. The control unit 501 realizes control of applying voltage to the static elimination roller 322 and the ionizer 323 via the voltage application controller 321. The ROM 504 stores a boot program for the static elimination device 200-3a, a control program for the operation unit 205, a static elimination processing program for the static elimination processing unit 503, etc. Then, the control unit 501 loads necessary programs from the ROM 504 into the RAM 505 as appropriate and executes them.

[0019] (Static charge removal treatment) Here, the static elimination process performed by the static elimination unit 503 will be described with reference to Fig. 7. Fig. 7 is a schematic diagram showing how the static elimination process is performed by the static elimination device 200-3a on a sheet 701 that has been printed by the printing device 100. First, the sheet 701 is conveyed via a conveying path 704 to a developing / transferring section consisting of the photosensitive drum 304 and the transfer drum 305, where toner is placed on the sheet 701. The charged toner 702 placed on the sheet 701 is negatively charged, and the sheet 701 is then fixed through the fixing device 308 and conveyed to the charge removing device 200-3a with the print surface 703 side negatively charged. The static elimination device 200-3a is equipped with a positively charged static elimination roller 322, which applies a positive charge (applied voltage value) to the negatively charged print surface 703 by contact static elimination with the roller, thereby eliminating the charged state. The static elimination roller 322 performs static elimination processing by the applied voltage value set by the control unit 501, but the voltage applied to the sheet 701 is changed halfway through the static elimination processing of the sheet by changing the charge amount by the control unit 501. By doing so, it is possible to change the static elimination effect for each area within one sheet. However, it is assumed that negative charges that could not be removed by the static elimination processing by the static elimination roller 322, or positive charges that are reversely charged, remain on the sheet 705 after passing through the static elimination roller. Therefore, the static elimination device 200-3a described in this embodiment is further configured to be equipped with an ionizer 323 downstream of the static elimination roller 322. The ionizer 323 is a device that applies a voltage to an electrode needle provided in the device to generate a corona discharge, and uses the ions thus generated to eliminate the charge. In this way, the static elimination roller 322 performs rough static elimination, and the ionizer adjusts the remaining charge, so that the static elimination process is performed on the sheet 707 discharged from the static elimination device 200-3a, and the charge is eliminated.

[0020] Returning to the explanation using the cross-sectional view of Fig. 3, the static eliminator 200-3a has a static elimination roller 322 and a pair of rollers, and the sheet transported to the static eliminator 200-3a is transported while being sandwiched between the two rollers, and the above-mentioned static elimination is performed by the static elimination roller 322. Thereafter, the sheet is transported outside the device by the transport roller 324, and the residual charge is eliminated by the ionizer 323.

[0021] (Saddle stitching machine) Next, the saddle stitching machine 200-3b will be described. The sheet processing by the saddle stitching machine 200-3b includes, for example, saddle stitching, punching, cutting, shift discharge, folding, stapling, etc. Hereinafter, these jobs will be referred to as "saddle stitching jobs". When processing a saddle stitching job, the control unit 205 first conveys the sheets of this job printed by the printing device 100 to the saddle stitching machine 200-3b, and then the control unit 205 causes the saddle stitching machine 200-3b to execute sheet processing of this job. Then, the control unit 205 holds the printed matter of the saddle stitching job that has been subjected to sheet processing by the saddle stitching machine 200-3b in the discharge destination Z of the saddle stitching machine 200-3b. Note that there are multiple discharge destination candidates for the discharge destination Z. This is used when the saddle stitching machine 200-3b can execute multiple types of sheet processing and a discharge destination is divided for each sheet processing. In this embodiment, a detailed description of the conveying procedure of the saddle stitching job is omitted.

[0022] Printing, static elimination Next, the printing process and the static electricity removal process in the image forming apparatus 1000 of this embodiment will be described with reference to the flowchart in Fig. 8. For the sake of explanation, the received print job is taken as an example of the image 900 in Fig. 9, and the flow of executing the printing and static electricity removal processes will be described. The image 900 is A4 data, and the "image" here refers to the image formed on each page of the print job before RIP. Furthermore, in this embodiment, printing of PDL data will be described as a print job, but it may be another print job such as copying. The following processing is realized by the control unit 205, which is the CPU of the printing device 100, loading a program stored in the ROM 207 or HDD 209 into the RAM 208 and executing it. First, in S801, the control unit 205, which is the CPU of the printing device 100, acquires whether the state of the static elimination process of the static elimination device 200-3a is ON or OFF. This process is realized by the control unit 205 of the printing device 100 sending an inquiry to the control unit 501, which is the CPU of the static elimination device 200-3a. Then, the control unit 501 of the static elimination device 200-3a acquires the state of the mode setting switch 601 of the operation unit 502 and the voltage value to be applied that is set by the adjustment dial 602, and returns the information to the control unit 205 of the printing device 100. Next, in S802, the control unit 205, which is the CPU of the printing apparatus 100, displays on the operation unit 204 of the printing apparatus 100 the ON / OFF state of the static elimination process of the static eliminator 200-3a and the applied voltage value acquired in S801. In the next step S803, the control unit 205 of the printing device 100 determines whether a print job has been submitted. If a print job has not been submitted (No in S803), the control unit 205 returns the process to S801 and continues to display the ON / OFF status of the static electricity removal process on the operation unit 204. On the other hand, if a print job has been submitted (Yes in S803), the control unit 205 advances the process to S804. In S804, the control unit 205, which is the CPU, interprets the image 900 as PDL data and performs RIP processing. RIP processing is processing to convert PDL data into a raster image. An example in which the coordinate values ​​of each pixel of the image 900 and the gradation values ​​(0 to 255) of cyan, magenta, yellow, and black (CMYK) of the pixel are converted into image data by the RIP processing is shown as image data 911 to 913 in FIG. For example, image data 911 indicates that the pixel at coordinates (2500,100) will be colored with (C,M,Y,K)=(0,0,0,0). In S805, the control unit 205 acquires the ON / OFF state of the static elimination process of the static elimination device 200-3a and determines the state of the static elimination process. If the static elimination process is ON (Yes in S805), the control unit 205 advances the process to S806, and if the static elimination process is OFF (No in S805), the control unit 205 sets the applied voltage value to 0 and advances the process to S808.

[0023] (Calculation process of correction value of applied voltage value: S806) The process of S806 will now be described in detail with reference to the flowchart of FIG. In S1001, S806 is a flow for calculating the amount of toner required for printing from the image data in order to derive the optimal applied voltage value for the received image data, and determining a coefficient that will result in an appropriate applied voltage value to the discharging roller according to the amount of toner used. The control unit 205 of the printing device 100 converts the image data for each pixel using a toner usage table to calculate the toner usage required for each pixel. The toner usage table is a table for converting the toner amount from the density of each of CMYK. 9 as an example, image data 912 is converted into toner usage data 922 by table conversion using the toner usage table in S1001. Note that image data, toner usage data, and toner usage described later exist for all pixels in a page, but for the sake of explanation, image data 911 to 913 are used as an example in this embodiment. Toner usage data 922 indicates that a pixel at coordinates (2500, 3000) requires a toner amount (0 to 255) of (C, M, Y, K) = (200, 200, 200, 255). Furthermore, a value expressing all toner required for this pixel in a range of 0 to 255 is calculated as the toner usage. For toner usage data 922, (200 + 200 + 200 + 255) / (255 + 255 + 255 + 255) × 255 = 214, and toner usage 932 can be calculated as 214. When the toner usage data 921 to 923 are calculated in the same manner, the toner usage data 931 becomes 0 and the toner usage data 933 becomes 214. In S1002, the control unit 205 adds up the calculated amounts of toner used to calculate the amount of toner used for one page. In this embodiment shown in FIG. 9, the toner usage amount 940 for one page is specifically calculated. The colored area of ​​image 900 is 4000×7000=28,000,000. Toner usage per pixel: 214 Toner usage per page: 940: 28,000,000 x 214 = 5,992,000,000 It is calculated as follows. In S1003, the control unit 205 determines a toner usage coefficient 950 from the toner usage amount for one page 940. The toner usage coefficient 950 is a coefficient for correcting the currently set applied voltage value by the amount of toner usage. Specifically, the coefficient is derived assuming that the toner is applied to the entire sheet as 100%. Since the image 900 is A4 size and the maximum toner usage amount is 255, Number of pixels on the entire sheet: 4960 x 7015 Maximum toner usage per sheet: 4960 x 7015 x 255 = 8,872,572,000 And then, Toner usage coefficient 950: 5,992,000,000 / 8,872,572,000×100=67.5% It is calculated as follows. After completing this step, the control unit 205 returns the process to after S806 in FIG.

[0024] (Flow in Figure 8) In this embodiment, steps S804 to S806 have been described as a flow in which the control unit 205 of the printing apparatus 100 calculates a correction value for the applied voltage value for image data after RIP, but these steps may also be performed by the client computer 102 before submission. In this case, the client computer 102 inputs the applied voltage value (or a correction value for the applied voltage value) as a sheet parameter together with the PDL data to be submitted. Then, the control unit 205 stores the applied voltage value as a sheet parameter in the HDD 209 when receiving a print job. In this case, the control unit 205 may proceed to the next step S807 using the received applied voltage value without performing step S806. Next, in S807, the control unit 205 adjusts the applied voltage value using the toner usage amount coefficient 950 calculated in S806. (Applied voltage adjustment process: S807) The process of S807 will now be described with reference to the flowchart of Fig. 11. S807 is a flow for finding an optimum applied voltage value for the received print job by adjusting the applied voltage value preset in the printing device 100 using the toner usage coefficient 950. First, in step S1101, the control unit 205 acquires an applied voltage value from the control unit 501 based on the sheet parameters set for the sheet type of the print job in the static eliminator 200-3a. In this embodiment, the acquired applied voltage value is set to +3 [kV]. Next, in S1102, the control unit 205 adjusts the applied voltage value for the image 900 from the toner usage coefficient 950 calculated in S806 based on the acquired applied voltage value. For the adjustment, the charge state (applied voltage value set in the sheet parameters) of a blank sheet (without toner) of that sheet type and the charge state of a full solid image of (C,M,Y,K)=(255,255,255,255) are measured in advance. Then, the applied voltage adjustment value is calculated by multiplying the charge amount difference by the toner usage coefficient. As an example, a case where the charge amount of a blank sheet of paper is −1.0 [kV] and the charge amount of a full solid image is −7.0 [kV] will be described below. This indicates that the toner layer causes a maximum charge of -6.0 kV, so next, an applied voltage value is determined that offsets this by adjusting the applied voltage value according to the amount of toner used. In this embodiment, the toner usage coefficient is 67.5%, so The charge of image 900 is: (-1.0) + (-6.0 x 0.675) = -5.1 [kV] In order to offset this, the control unit 205 sets +5.1 [kV] as the applied voltage value in the static elimination processing unit 503 via the control unit 501.

[0025] In S1103, the control unit 205 resets the applied voltage value calculated in S1102 to the static elimination unit 503 via the control unit 501 of the static elimination device 200-3a. In addition, in S1102, in this embodiment, the flow for adjusting the applied voltage value by coefficientizing the state in which toner is applied to the entire sheet from a blank sheet as 100% has been described. However, depending on the sheet, the required applied voltage value may not necessarily be proportional to the amount of toner used. In this case, the applied voltage value may be adjusted in stages according to the sheet characteristics. For example, the applied voltage may be adjusted in stages such that no adjustment is required when the toner usage coefficient is 70 or less, +1 kV for 71 to 90, and +2 kV for 91 to 100. After completing this step, the control unit 205 returns the process to after S807 in FIG. (Flow in Figure 8) In S808, the control unit 205 of the printing apparatus 100 executes the printing process in the printing apparatus 100, and causes the static elimination device 200-3a to perform static elimination processing with the applied voltage value adjusted in S807, and then ends this processing.

[0026] As described above, the applied voltage value of the static eliminator 200-3a can be controlled according to the amount of toner used on the sheet to be printed. In addition, since the applied voltage value corresponding to the image that the user actually prints can be set, it is possible to provide a high-quality product without causing discharged paper adhesion. In the image forming apparatus 1000, a message such as "Enable static elimination voltage adjustment for each page" may be displayed on the operation unit 204, and a switch for switching between enabling and disabling this embodiment may be provided.

[0027] [Embodiment 2] In the first embodiment, the toner usage amount is calculated from the RIP image using the toner usage amount table for the image 900 of the input print job, and the coefficient is applied to the preset applied voltage value to derive the optimum applied voltage value for the input print job. In the present embodiment, the area of ​​the region in which the toner is used, that is, the area of ​​the non-background portion, is calculated for the image 900 of the input print job, instead of the toner usage amount, and the coefficient is applied. An example of deriving the optimum applied voltage value for the input print job by multiplying the preset applied voltage value by the coefficient will be described. Note that since Figs. 1 to 7 are the same as those in the first embodiment, the description will be omitted.

[0028] Printing, static elimination The printing and static electricity removal process of the second embodiment will be described with reference to Fig. 8. The following process is realized by the control unit 205, which is the CPU of the printing device 100, loading a program stored in the ROM 207 or HDD 209 into the RAM 208 and executing it. 8, steps S801 to S805 and S808 are the same as those in the first embodiment, and therefore will not be described. For the sake of explanation, the received print job is image 1200 in FIG. 12, and the flow of printing this job and removing static electricity will be described. Image 1200 is A4 data. The process of S806 will be described with reference to the flowchart in Fig. 13. S806 is a flow for calculating the area of ​​the region in which toner is used from the image data and determining a coefficient that will result in an appropriate applied voltage value according to the calculated area in order to derive an optimal applied voltage value for the received image data.

[0029] (Calculation process of correction value of applied voltage value: S806) In S1301, the control unit 205 extracts a non-background region from the RIP image created in S804. An outline image 1210 in Fig. 12 is an image obtained by extracting the background region and the non-background region from the image 1200 by performing image area separation. In S1302, the control unit 205 calculates the area of ​​the contour image 1210. Here, the obtained area is set to 28,000,000. If the contour shape is complex, the area may be calculated by approximating it to a rectangle. In S1303, the control unit 205 determines a toner area coefficient based on the area ratio between the sheet and the outline image. The size of the sheet for image 1200 is A4 data, so The sheet area is: 4960 x 7015 = 34,794,400 Therefore, in this embodiment, The toner area coefficient of 1230 is: 28,000,000 / 34,794,400×100=80.5%. After completing this step, the control unit 205 returns the process to after S807 in FIG.

[0030] (Flow in Figure 8) In S807, the control unit 205 adjusts the applied voltage value using the toner area coefficient calculated in S806. (Applied voltage adjustment process: S807) The process of S807 will now be described with reference to the flowchart of Fig. 14. S807 is a flow for finding an optimum applied voltage value for a received print job by adjusting the applied voltage value preset in the printing device 100 using the toner area coefficient. In S1401, the control unit 205 acquires the applied voltage value set in the static elimination processing unit 503 from the control unit 501. In this embodiment, the acquired applied voltage value is set to +3 [kV]. In S1402, the control unit 205 adjusts the applied voltage value for the image 1200 from the toner area coefficient 1230 calculated in S806 based on the acquired applied voltage value. The adjustment is performed by measuring in advance the charge state (applied voltage value set in the sheet parameters) of a blank sheet (without toner) of that sheet type and the charge state of a full solid image of (C,M,Y,K)=(255,255,255,255). Then, the charge amount difference is multiplied by the toner area coefficient to calculate the toner area coefficient. For example, let us consider the case where the charge of a blank sheet of paper is -1.0 kV and the charge of a full solid image is -7.0 kV. Since the toner layer indicates that the image will be charged to a maximum of -6.0 kV, we determine the applied voltage value that will offset this by adjusting the applied voltage value according to the toner area. In this embodiment, the toner area coefficient calculated in S1303 is 80.5%, so The charge of image 900 is: (-1.0) + (-6.0 x 0.805) = -5.8 [kV] In order to offset this, the control unit 205 sets +5.8 [kV] as the applied voltage value in the static elimination processing unit 503 via the control unit 501.

[0031] In S1403, the control unit 205 resets the applied voltage value calculated in S1402 for the control unit 501 of the static eliminator 200-3a. After completing this step, the control unit 205 returns the process to after S807 in FIG. In addition, in S1402, in this embodiment, the flow for adjusting the applied voltage value by coefficientizing the state in which toner is applied to the entire sheet from blank paper as 100% has been described. However, depending on the sheet, the required applied voltage value may not necessarily be proportional to the toner area, so the applied voltage value may be adjusted in stages according to the sheet characteristics. For example, the applied voltage may be adjusted in stages such that no adjustment is required when the toner area coefficient is 70 or less, +1 kV for 71 to 90, and +2 kV for 91 to 100.

[0032] As described above, the applied voltage value of the static eliminator 200-3a can be controlled according to the amount of toner used on the sheet to be printed. In addition, since the applied voltage value corresponding to the image that the user actually prints can be set, it is possible to provide a high-quality product without causing discharged paper adhesion. In the image forming apparatus 1000, a message such as "Enable static elimination voltage adjustment for each page" may be displayed on the operation unit 204, and a switch for switching between enabling and disabling this embodiment may be provided.

[0033] [Embodiment 3] In the first and second embodiments, the optimum applied voltage value is calculated for the image 900 of the input print job by multiplying the applied voltage value set for the sheet type of the input print job by a coefficient calculated based on the amount of toner used or the area of ​​the non-background part. In this embodiment, the image 900 of the input print job is first divided into bands of a predetermined width in the sub-scanning direction, and the applied voltage value using the coefficient according to the amount of toner used or the area of ​​the non-background part is calculated for each band. Then, an example of static elimination by the static elimination roller is described, in which the static elimination is performed by switching to the optimum applied voltage for each band. In this embodiment, an example of adjusting the applied voltage value using the coefficient according to the amount of toner used in the first embodiment is described. Note that FIG. 1 to FIG. 7 are the same as in the first embodiment, and therefore the description will be omitted.

[0034] Printing, static elimination The printing and static electricity removal process of the third embodiment will be described with reference to Fig. 16. Note that the following process is realized by the control unit 205, which is the CPU of the printing device 100, loading a program stored in the ROM 207 or HDD 209 into the RAM 208 and executing it. 16, steps S801 to S808 are the same as those in the first embodiment, and therefore description thereof will be omitted. This flow is for dividing the post-RIP image data of each page of a received print job by band, calculating the amount of toner used for printing by band, and determining a coefficient that will result in an optimum applied voltage value according to the amount of toner used. For the sake of explanation, the received print job is image data 1500 in FIG. 15, and the flow for printing this job and removing static electricity will be described. The image data 1500 is A4 data. In S1601, the control unit 205 divides the image 1500 at regular intervals in the sub-scanning direction. In this embodiment, an example will be described in which the image 1500 is divided into four equal parts, band 1511, band 1512, band 1513, and band 1514. Each band is image data of 4960 pixels in the main scanning direction and 1754 (=7015 / 4) pixels in the sub-scanning direction. As described in the first embodiment, in S806, the control unit 205 obtains a toner usage coefficient as a correction value for the applied voltage value for the image data of the band 1511. For this purpose, table conversion is performed using a toner usage table, and the toner usage amount 1521 and toner usage coefficient 1531 of the band 1511 are calculated from the sum. In this embodiment, the calculation method is the same as in the first embodiment, so details are omitted, but the toner usage amount 1521 is calculated to be 1,739,272,012, and the toner usage coefficient 1531 is calculated to be 78.4%, respectively. As described in the first embodiment, in S807, the control unit 205 multiplies the toner usage coefficient 1521 obtained in S806 based on the currently set applied voltage value, and adjusts the applied voltage value for the image 1500. The adjustment is performed by measuring the charge state (applied voltage value set in the sheet parameters) of a blank sheet (without toner) of that sheet type and the charge state of a full solid image of (C, M, Y, K) = (255, 255, 255, 255) in advance. Then, the charge amount difference is multiplied by the toner area coefficient to calculate. For example, if the charge amount of the blank sheet is -1.0 [kV] and the charge amount of the full solid image is -7.0 [kV], it is found that the toner layer charges the image at a maximum of -6.0 [kV]. Then, the applied voltage value that offsets the charge amount is calculated by adjusting the applied voltage value according to the toner usage amount. In this embodiment, since the toner usage amount coefficient is 78.4%, the charge amount of the image 1500 is estimated to be (-1.0) + (-6.0 x 0.784) = -5.7 [kV]. To offset this, the control unit 205 sets +5.7 [kV] as the applied voltage value in the static elimination processing unit 503 via the control unit 501 .

[0035] The control unit 205 resets the applied voltage value taking into account the adjustment value for the control unit 501 of the static eliminator 200-3a. In this embodiment, +5.7 [kV] taking into account the adjustment result of +4.7 [kV] is set as the applied voltage value. The control unit 205 repeats the above-described flow from S806 to S807 for the number of bands divided in S1601 (S1602). Note that detailed calculations are omitted because they are similar to those in the first embodiment, but since the toner usage amount of band 1513 and band 1514 is small, the adjusted applied voltage value for each band remains the original applied voltage value of +1 [kV]. In S1603, the control unit 205 notifies the control unit 501 of the static eliminator 200-3a of the applied voltage value calculated for each band, and sets the applied voltage value for each band. Finally, in S808, the control unit 205 of the printing apparatus 100 executes the printing process in the printing apparatus 100. When the static elimination process is performed in the static elimination device 200-3a at the applied voltage value adjusted in S807, the static elimination processing unit 503 instructs the static elimination roller 704 to perform the static elimination process at an applied voltage value that differs for each band depending on the applied voltage value set by the control unit 501. Then, the control unit 205 ends this process. In this embodiment, the control unit 501 applies different voltages to each area of ​​a sheet by changing the applied voltage value to the static electricity removal roller 704 via the static electricity removal processing unit 503 during the static electricity removal process of the sheet. This makes it possible to cancel the amount of charge on the toner layer in band units compared to the case where a uniform voltage is applied to the entire sheet, thereby obtaining a higher static electricity removal effect. Therefore, no discharged paper adhesion occurs, and an appropriate product can be provided to the user. In this embodiment, an example in which the area is divided into four bands has been described, but the number of bands can be increased or decreased depending on the performance of the voltage application to the static electricity removing roller. In the image forming apparatus 1000, a message such as "Enable static elimination voltage adjustment for each page" may be displayed on the operation unit 204, and a switch for switching between enabling and disabling this embodiment may be provided. The above describes the case where the image forming apparatus receives a print job from a client computer. In addition, the applied voltage for the static elimination process can be adjusted based on image data in the case of copy processing using the scanner unit 201 of the image forming apparatus and in the case of receiving a fax using a fax function (not shown). Furthermore, by measuring the amount of charge with a sensor or the like, the calculated amount of charge can be compared with the actual amount of charge, and feedback can be provided to enable more accurate static elimination processing. Furthermore, by measuring environmental parameters such as humidity and temperature with a sensor or the like and feeding back this information, it is possible to perform the static elimination process with high accuracy.

[0036] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0037] The disclosure of this embodiment includes the following configuration, method, and program. (Configuration 1) a receiving means for receiving a print job from a client computer connected via a network; a printing means for executing a printing process on a sheet based on the contents of the print job; An image forming apparatus including a static elimination device for performing static elimination processing on the printed sheet, an adjustment unit that adjusts a voltage value applied to the sheet by the static eliminator based on an amount of charge calculated from image data of a page of a print job; An image forming apparatus comprising: (Configuration 2) The charge amount is It is calculated from the charge amount of a blank sheet of the same sheet, the charge amount of a toner solid image of all pixels, and the toner usage amount of the image data of the print job. 2. The image forming apparatus according to claim 1, (Configuration 3) The charge amount is It is calculated from the charge amount of a blank sheet of the same sheet, the charge amount of a toner solid image of all pixels, and the area of ​​the region where the toner of the image data of the print job is used. 2. The image forming apparatus according to claim 1, (Configuration 4) The adjustment means is The voltage applied is adjusted in stages to match the sheet characteristics based on the charge amount of blank paper, the charge amount of a full-pixel toner solid image, and the toner usage amount of the print job for the same sheet. 4. The image forming apparatus according to any one of configurations 1 to 3. (Configuration 5) The adjustment means is Dividing the image data of the page of the print job into band units of a predetermined width, and adjusting the voltage value applied to the sheet by the static eliminator based on the calculated charge amount for each band unit. 5. The image forming apparatus according to any one of configurations 1 to 4. (Method 1) A method for controlling an image forming apparatus including a receiving unit that receives a print job from a client computer connected via a network, a printing unit that executes a print process on a sheet based on the contents of the print job, and a static elimination device that performs a static elimination process on the printed sheet, comprising: an adjustment step of adjusting a voltage value applied to the sheet by the static eliminator based on an amount of charge calculated from image data of a page of a print job; 11. A method for controlling an image forming apparatus comprising: (Program 1) A program for causing a computer to execute the control method for an image forming apparatus according to the first method. [Explanation of symbols]

[0038] 205 Control Unit 200-3a Static eliminator 501 Control section 503 Static electricity removal processing unit 704 Antistatic roller

Claims

1. A printing system comprising a printing device and an antistatic device for printing print jobs on multiple types of sheets, A means for identifying the amount of charge from the pixel values ​​of the image data of the page of the print job, A printing system comprising a static discharge means that performs static discharge processing on the sheet based on the amount of charge identified by the specified means, A printing system characterized in that the pixel values ​​have a range of 0 to 255 for cyan, magenta, yellow, or black.

2. The printing system according to Claim 1, further comprising an adjustment means for adjusting the voltage value applied to the static elimination device in steps according to the sheet characteristics, based on the amount of charge of a blank sheet, the amount of charge of a full-surface solid image, and the amount of toner used in the image data of the page, for the same type of sheet as the sheet.

3. The printing system according to claim 1, characterized in that the amount of charge is calculated based on the amount of charge of a blank sheet of the same type as the sheet, the amount of charge of a full-surface solid image, and the area in the image data of the page where toner is used.

4. A division means for dividing the image data of the job page into bands of a predetermined width, An adjustment means for adjusting the voltage value applied to the static elimination device based on the amount of charge calculated for each band, The printing system according to claim 1, further comprising:

5. A determination means for determining a first applied voltage value corresponding to the type of sheet, An adjustment means for adjusting the first applied voltage value to a second applied voltage value based on the amount of charge, Setting means for setting the second applied voltage value for the static discharge process, The printing system according to claim 1, further comprising:

6. A control method for a printing system comprising a printing device and an anti-static device for printing print jobs on multiple types of sheets, A process for determining the amount of charge from the pixel values ​​of the image data of the page of the print job, The process includes a static discharge step which performs static discharge on the sheet based on the amount of charge identified by the specified step, A method for controlling a printing system, characterized in that the pixel values ​​have a range of 0 to 255 for cyan, magenta, yellow, or black.

7. A program for causing a computer to execute the printing system control method described in claim 6.

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