JP2025112032A - Image forming apparatus - Google Patents

Abstract

To accurately adjust an image forming condition with a simple method.SOLUTION: An image forming apparatus comprises: an image reading unit 231 that reads an image for adjustment formed on a sheet; and a CPU 222 that adjusts an image forming condition on the basis of a result of reading of the image for adjustment performed by the image reading unit 231. The CPU 222 forms the image for adjustment on the sheet while a print job for forming a plurality of images on a plurality of sheets is executed, and adjusts the image forming condition on the basis of the result of reading of the image for adjustment performed by the image reading unit 231. The CPU 222 forms the image for adjustment on plain paper when the plurality of sheets are embossed paper.SELECTED DRAWING: Figure 2

Description

The present invention relates to image forming devices such as printers, copiers, facsimiles, and multifunction devices.

Printed materials produced by commercial printing presses require stable image density. Patent Document 1 discloses an image forming device that aims to stabilize image density. This image forming device creates an adjustment chart by printing an adjustment image for adjusting image density on a sheet. The adjustment chart is read by an image reading sensor installed in the sheet transport path. The image forming device achieves stable image density by periodically printing the adjustment chart while a print job is being executed and feeding back the results of reading the adjustment image by the image reading sensor to the image formation conditions.

Japanese Patent Application Laid-Open No. 2006-11285

Image density adjustments are made for each type of sheet. For example, when a print job is executed using embossed paper with an uneven surface, an adjustment chart is created using the embossed paper to adjust the image density. The unevenness of the embossed paper makes the distance between the surface and the image reading sensor unstable. As a result, the image reading sensor cannot accurately read the adjustment image from the embossed paper adjustment chart. This means that image density adjustments cannot be made with high accuracy when using embossed paper. Furthermore, similar problems arise when optically reading an adjustment chart to adjust image formation conditions, regardless of image density. Therefore, the present invention aims to appropriately stabilize image density regardless of the type of sheet used in a print job.

The image forming apparatus of the present invention comprises an image forming means that forms an image on a sheet based on image formation conditions; a reading means that reads the adjustment image formed on the sheet; an adjustment means that adjusts the image formation conditions based on the results of reading the adjustment image by the reading means; and a control means that, while a print job is being executed in which the image forming means forms multiple images on multiple sheets, causes the image forming means to form the adjustment image on the sheet and causes the adjustment means to adjust the image formation conditions based on the results of reading the adjustment image by the reading means, and when the multiple sheets are of a first type, causes the control means to form the adjustment image on a second type of sheet that is different from the first type.

According to the present invention, image density can be appropriately stabilized regardless of the type of sheet used for the print job.

FIG. 1 is a diagram illustrating the configuration of an image processing system. system configuration diagram. FIG. 1 is a diagram illustrating the configuration of an image forming apparatus. An explanatory diagram of a CIS. 10A to 10G are diagrams illustrating examples of setting screens. FIG. 10 is a diagram illustrating an example of job information. FIG. 10 is a diagram illustrating an example of automatic adjustment information. FIG. 10 is a diagram illustrating an adjustment chart. 10 is a flowchart showing a printing process. 10 is a flowchart showing a job in which paper feed stage switching is performed and automatic adjustment is enabled. 10 is a flowchart showing a job in which automatic adjustment is enabled without switching of paper feed trays. 10 is a flowchart illustrating an auto-tuning disabled job.

The following describes the embodiments in detail with reference to the drawings.

(Image Processing System)
1 is a configuration diagram of an image processing system including an image forming apparatus according to this embodiment. The image processing system includes an image forming apparatus 101 and an external controller 102. The image forming apparatus 101 is, for example, a multifunction peripheral (MFP), a multifunction peripheral (MFP), etc. The external controller 102 is, for example, an image processing controller, a digital front end (DFE), a print server, etc.

The image forming apparatus 101 and external controller 102 are communicatively connected via an internal LAN (Local Area Network) 105 and a video cable 106. The external controller 102 is connected to a client PC (Personal Computer) 103 via an external LAN 104. The external controller 102 obtains print instructions (print jobs) from the client PC 103.

A printer driver with the function of converting image data into a print description language that can be processed by the external controller 102 is installed on the client PC 103. The user can issue printing instructions via the printer driver using various applications. The printer driver sends image data to the external controller 102 based on a job from the user. The external controller 102 accepts a print job containing image data from the client PC 103, performs data analysis and rasterization processing, and instructs the image forming device 101 to print (form an image) based on the image data.

The image forming apparatus 101 is configured by connecting devices with multiple different functions, including the printing device 107, and is capable of complex printing processes such as bookbinding. The image forming apparatus 101 of this embodiment is equipped with the printing device 107 and a finisher 109. The printing device 107 forms an image on a sheet fed from a paper feed unit located at the bottom of the main body using a developer (e.g., toner). The printing device 107 forms images in yellow (Y), magenta (M), cyan (C), and black (K). A full-color image is formed on the sheet by superimposing images of each color. The sheet on which the image has been formed is transported from the printing device 107 to the finisher 109. The finisher 109 stacks the sheet on which the image has been formed on a stack tray 332.

This image processing system is configured such that an external controller 102 is connected to an image forming apparatus 101, but the external controller 102 is not necessarily required. For example, the image forming apparatus 101 may be configured to directly receive a print job containing image data from a client PC 103 via an external LAN 104. In this case, the image forming apparatus 101 will perform the data analysis and rasterization processes already performed by the external controller 102. In other words, the image forming apparatus 101 and the external controller 102 may be configured as an integrated unit.

(System configuration)
2 is a diagram showing the system configuration for controlling the operation of the image processing system. Here, the system configurations of the image forming apparatus 101, the external controller 102, and the client PC 103 will be described.

Printing Device The printing device 107 includes a communication interface (I/F) 217, a LAN I/F 218, and a video I/F 220 for communicating with other devices. The printing device 107 includes a CPU (Central Processing Unit) 222, a memory 223, a storage 221, an image reading unit 231, and an image processing unit 232 for controlling the operation of the printing device 107. The printing device 107 includes an exposure unit 227, an image creating unit 228, a fixing unit 229, and a paper feeding unit 230 for forming an image. The printing device 107 includes an operation unit 224 and a display 225 as user interfaces. These components are connected to each other via a system bus 233 so that they can communicate with each other.

The communication I/F 217 is connected to the finisher 109 via a communication cable 249 and controls communication with the finisher 109. When the printing device 107 and finisher 109 operate in cooperation, information and data are sent and received via the communication I/F 217. The LAN I/F 218 is connected to the external controller 102 via the internal LAN 105 and controls communication with the external controller 102. The printing device 107 receives print settings and image data from the external controller 102 via the LAN I/F 218. The video I/F 220 is connected to the external controller 102 via the video cable 106 and controls communication with the external controller 102. The printing device 107 receives image data representing an image to be printed from the external controller 102 via the video I/F 220.

The CPU 222 comprehensively controls image processing and printing by executing computer programs stored in the storage 221. The memory 223 provides a work area for the CPU 222 when it executes various processes. When performing image formation processing, the CPU 222 controls the exposure unit 227, image creation unit 228, fixing unit 229, and paper feed unit 230.

The exposure unit 227 includes a photoconductor, a charging wire that charges the photoconductor, and a light source that exposes the photoconductor charged by the charging wire to light to form an electrostatic latent image on the photoconductor. The photoconductor may be, for example, a photosensitive belt with a photosensitive layer formed on the surface of a belt-shaped elastic member, or a photosensitive drum with a photosensitive layer formed on the surface of a cylinder. A charging roller may also be used instead of the charging wire. The exposure unit 227 charges the surface of the photoconductor to a uniform negative potential using the charging wire. The exposure unit 227 outputs laser light from the light source based on image data. The laser light scans the uniformly charged surface of the photoconductor. This causes the potential of the photoconductor at the position irradiated by the laser light to fluctuate, forming an electrostatic latent image on the surface. Four photoconductors are provided, one for each of the four colors: yellow (Y), magenta (M), cyan (C), and black (K). Electrostatic latent images corresponding to different color images are formed on each of the four photoconductors.

The image forming unit 228 transfers the toner image formed on the photosensitive member onto a sheet. The image forming unit 228 is equipped with a developing unit, a transfer unit, and a toner supply unit. The developing unit forms a toner image by attaching negatively charged toner from a developing cylinder to an electrostatic latent image formed on the surface of the photosensitive member. Four developing units are provided, one for each of the four colors: yellow (Y), magenta (M), cyan (C), and black (K). The developing units visualize the electrostatic latent image on the photosensitive member using toner of the corresponding color. When the amount of toner inside the developing unit runs low due to the formation of a toner image, the toner supply unit replenishes the toner.

The transfer unit has an intermediate transfer belt and transfers toner images from each photosensitive drum to the intermediate transfer belt. Primary transfer rollers are located opposite the photosensitive drums across the intermediate transfer belt. When a positive potential is applied to the primary transfer rollers, the toner images from each of the four photosensitive drums are transferred onto the intermediate transfer belt in a superimposed state. This forms a full-color toner image on the intermediate transfer belt. The toner image formed on the intermediate transfer belt is transferred to a sheet by a secondary transfer roller, described below. When a positive potential is applied to the secondary transfer rollers, they transfer the full-color toner image from the intermediate transfer belt to the sheet.

The fixing unit 229 fixes the transferred toner image onto the sheet. The fixing unit 229 has a heater and a pair of rollers. The fixing unit 229 uses the heater and the pair of rollers to heat and pressurize the toner image on the sheet, melting and fixing the toner image to the sheet. This forms an image on the sheet. The paper feed unit 230 has transport rollers and various sensors on the transport path, and controls the sheet feeding operation.

The image reading unit 231 reads the image formed on the conveyed sheet based on instructions from the CPU 222. For example, when adjusting image formation conditions, the CPU 222 uses the image reading unit 231 to read an adjustment image for the image formation conditions formed on the sheet. The image processing unit 232 sets gain adjustment values for the image reading unit 231 based on the reading results from the image reading unit 231. Such processing by the image processing unit 232 is reflected in the image reading results from the image reading unit 231. The operation unit 224 is an input device that accepts various setting inputs and operation instructions from the user. The operation unit 224 is, for example, various input keys or a touch panel. The display 225 is an output device that displays setting information for the image forming apparatus 101 and the processing status (status information) of a print job.

Finisher The finisher 109 is, for example, a large-capacity stacker. The finisher 109 includes a communication I/F 241, a CPU 242, a memory 243, and a paper discharge control unit 244. These components are connected to each other via a system bus 245 so that they can communicate with each other. The communication I/F 241 is connected to the printing apparatus 107 via a communication cable 249 and controls communication between the finisher 109 and the printing apparatus 107. When the finisher 109 and the printing apparatus 107 operate in cooperation with each other, information and data are sent and received via the communication I/F 241. The CPU 242 executes a control program stored in the memory 243 and performs various controls necessary for paper discharge. The memory 243 stores the control program. The memory 243 also provides a work area for the CPU 242 when executing various processes. The paper discharge control unit 244 discharges the transported sheets to a stack tray 332 based on instructions from the CPU 242.

External Controller The external controller 102 includes a LAN I/F 213, a LAN I/F 214, and a video I/F 215 for communicating with other devices. The external controller 102 includes a CPU 208, a memory 209, and a storage 210 for controlling the operation of the external controller 102. The external controller 102 includes a keyboard 211 and a display 212 as user interfaces. These components are connected to each other via a system bus 216 so that they can communicate with each other.

The LAN I/F 213 is connected to the client PC 103 via the external LAN 104 and controls communication with the client PC 103. The external controller 102 obtains print jobs from the client PC 103 via the LAN I/F 213. The LAN I/F 214 is connected to the printing device 107 via the internal LAN 105 and controls communication with the printing device 107. The external controller 102 transmits print settings, image data, etc. to the printing device 107 via the LAN I/F 214. The video I/F 215 is connected to the printing device 107 via the video cable 106 and controls communication with the printing device 107. The external controller 102 transmits image data to the printing device 107 via the video I/F 215.

The CPU 208 executes computer programs stored in the storage 210 to comprehensively perform processes such as receiving image data sent from the client PC 103, RIP processing, and sending image data to the image forming apparatus 101. The memory 209 provides a work area for the CPU 208 to perform various processes. The keyboard 211 is an input device that accepts various setting inputs and operation instructions from the user. The display 212 is an output device that displays information about applications executed by the external controller 102 using still images and moving images.

・Client PC
The client PC 103 includes a CPU 201, a memory 202, a storage 203, a keyboard 204, a display 205, and a LAN I/F 206. These components are connected via a system bus 207 so as to be able to communicate with each other.

The CPU 201 controls the operation of the client PC 103 by executing computer programs stored in the storage 203. In this embodiment, the CPU 201 creates image data and sends print jobs. The memory 202 provides a work area for the CPU 201 to perform various processes. The keyboard 204 and display 205 are user interfaces. The keyboard 204 is an input device that accepts instructions from the user. The display 205 is an output device that displays information about applications running on the client PC 103 as still images or videos. The LAN I/F 206 is connected to the external controller 102 via the external LAN 104 and controls communication with the external controller 102. The client PC 103 sends print jobs to the external controller 102 via the LAN I/F 206.

The external controller 102 and image forming apparatus 101 are connected via an internal LAN 105 and a video cable 106, but any other configuration is acceptable as long as they are capable of transmitting and receiving the data necessary for printing, and for example, they may be connected by just a video cable. Memory 202, memory 209, memory 223, and memory 243 may each be a storage device for holding data and programs. These memories may be, for example, volatile RAM (Random Access Memory), non-volatile ROM (Read Only Memory), storage, USB (Universal Serial Bus) memory, etc.

(Configuration of image forming apparatus)
3 is a configuration diagram of the image forming apparatus 101. A display 225 is provided on the top of the printing device 107. The display 225 displays information on the printing status and settings of the image forming apparatus 101. Sheets on which images have been formed by the printing device 107 are conveyed to a finisher 109 provided downstream.

The printing device 107 includes a paper feed unit 230 consisting of a multi-tray paper feed stage 300, which is a manual feed tray, multiple paper feed decks 301 and 302, and a transport path 303. The multi-tray paper feed stage 300 and each of the paper feed decks 301 and 302 can each hold different types of sheets. The topmost sheet stored in the multi-tray paper feed stage 300 and each of the paper feed decks 301 and 302 is separated and fed to the transport path 303. The printing device 107 includes image forming units 304, 305, 306, and 307, which form images, as the exposure unit 227. The printing device 107 forms color images. To this end, the image forming unit 304 forms a black (K) image (toner image). The image forming unit 305 forms a cyan (C) image (toner image). The image forming unit 306 forms a magenta (M) image (toner image). The image forming unit 307 forms a yellow (Y) image (toner image).

The printing device 107 includes, as the image creation unit 228, an intermediate transfer belt 308 and a secondary transfer roller 309 onto which toner images are transferred from the image forming units 304, 305, 306, and 307. The intermediate transfer belt 308 rotates clockwise in the figure, and toner images are transferred and superimposed on each other from the image forming units 307, 306, 305, and 304 in that order. As a result, the intermediate transfer belt 308 carries a full-color toner image. As the intermediate transfer belt 308 rotates, it transports the toner image to the secondary transfer roller 309. A sheet is transported to the secondary transfer roller 309 via the transport path 303 in synchronization with the timing at which the toner image is transported to the secondary transfer roller 309. The secondary transfer roller 309 transfers the toner image on the intermediate transfer belt 308 onto the transported sheet.

The printing device 107 is equipped with a first fuser 311 and a second fuser 318 as the fixing unit 229. The first fuser 311 and the second fuser 318 have the same configuration and fix the toner image to the sheet. To this end, the first fuser 311 and the second fuser 318 each include a pressure roller and a heating roller. The sheet is heated and pressurized as it passes between the pressure roller and the heating roller, and the toner image is melted and pressed onto the sheet. After passing through the second fuser 318, the sheet is transported to the transport path 314. The second fuser 318 is located downstream of the first fuser 311 in the sheet transport direction, and is used to add gloss to the image on the sheet that has been fixed by the first fuser 311 and to ensure fixation. For this reason, the second fuser 318 may not be used depending on the type of sheet and the content of the image formation process. A transport path 312 is provided to transport the sheet that has been fixed by the first fixing device 311 without passing through the second fixing device 318.

Where conveying path 314 and conveying path 312 converge, conveying path 315 and inversion path 316 are provided. When double-sided printing is instructed, the sheet is conveyed to inversion path 316. The sheet conveyed to inversion path 316 has its conveying direction reversed and is conveyed to double-sided conveying path 317. The sheet is inverted by inversion path 316 and double-sided conveying path 317 so that the side on which the image is formed (first side) is turned over. The sheet is conveyed to conveying path 303 by double-sided conveying path 317, and passes through secondary transfer roller 309 and fixing unit 229, where an image is formed on the second side.

In the case of single-sided printing, or in the case of double-sided printing where images are formed on both sides, the sheet is transported to transport path 315. Transport path 323 is located downstream of transport path 315 in the sheet transport direction.

On the transport path 323, CISs (Contact Image Sensors) 321 and 322 are arranged facing each other across the transport path 323 as the image reading unit 231. Figure 4 is an explanatory diagram of CISs 321 and 322. CIS 321 is an optical sensor that reads an image of the top surface of a sheet transported on the transport path 323. CIS 322 is an optical sensor that reads an image of the bottom surface of a sheet transported on the transport path 323.

The CIS 321 includes an LED (Light Emitting Diode) 350 as a light source, a reading sensor 351 as a light-receiving unit, and a white reference plate 352. The LED 350 irradiates the upper surface of the sheet when the sheet, transported along the transport path 323, reaches the reading position. The reading sensor 351 includes multiple light-receiving elements (photoelectric conversion elements) in a direction perpendicular to the sheet transport direction. Therefore, the direction perpendicular to the sheet transport direction is the main scanning direction of the CIS 321. The reading sensor 351 receives light reflected from the sheet using the light-receiving elements. The multiple light-receiving elements of the reading sensor 351 output output values (electrical signals) based on the intensity of the received reflected light. The output values (electrical signals) output from the multiple light-receiving elements are transmitted to the CPU 222. In this manner, the image formed on the sheet is read. The white reference plate 352 is a calibration member (reference member) used during shading correction of the CIS 321. During shading correction, the LED 350 and reading sensor 351 move to a position where they can read the white reference plate 352. Alternatively, during shading correction, the white reference plate 352 moves to the reading position of the LED 350 and reading sensor 351. Shading correction of the CIS 321 is performed based on the reading results of the white reference plate 352.

Like CIS 321, CIS 322 includes an LED 353, a reading sensor 354, and a white reference plate 355. CIS 322 operates in the same manner as CIS 321, and reads the image formed on the underside of the sheet when the sheet being transported along transport path 323 reaches the reading position. In addition to CISs 321 and 322, image reading unit 231 can also be realized by a CCD or CMOS sensor.

The printing device 107 of this embodiment is capable of forming adjustment images for adjusting image formation conditions on both sides of a sheet. A sheet on which an adjustment image is formed is called an adjustment chart. The printing device 107 prints the adjustment image on a sheet to create an adjustment chart, and reads the adjustment image using CIS 321 and CIS 322. The images of the adjustment chart read by CIS 321 and CIS 322 are stored in memory 223. The CPU 222 refers to memory 223, analyzes the images read by CIS 321 and CIS 322, and feeds the results back into the image formation conditions to adjust the image formation conditions.

For example, when the internal temperature of the printing device 107 rises, the image density of the image formed on the sheet fluctuates compared to when the internal temperature of the printing device 107 is low. The printing device 107 creates an adjustment chart and detects the image density based on the reading results of the CISs 321 and 322. The CPU 222 adjusts the image formation conditions so that the detected image density becomes the ideal image density. For example, the CPU 222 obtains the amount of image density variation from the detected image density, and adjusts the image formation conditions based on the obtained amount of variation so that the image is printed at the same image density as when the internal temperature is low. The CPU 222 converts the image data based on the image formation conditions. The printing device 107 controls the image density of the image formed on the sheet by forming the image on the sheet based on the image data converted by the CPU 222. This allows the printing device 107 to suppress fluctuations in image density caused by fluctuations in the internal temperature.

The adjustment image formed on the adjustment chart may be an image for detecting image density, or may be an image for detecting geometric characteristics such as print position or shape, or an image for detecting color misalignment. When an adjustment image for detecting geometric characteristics is formed, the CPU 222 adjusts the image formation conditions to suppress fluctuations in the geometric characteristics based on the reading results of the CIS 321 (or CIS 322). When the CPU 222 forms an image based on the image formation conditions, the geometric characteristics of the image printed by the printing device 107 are adjusted to ideal geometric characteristics.

Furthermore, when an adjustment image for detecting color misalignment is formed, CPU 222 detects color misalignment based on the reading results of CIS 321 (or CIS 322). Based on the detected color misalignment, CPU 222 adjusts the image formation conditions to suppress color misalignment. CPU 222 corrects color misalignment by controlling the position of the image formed on the photosensitive element by exposure unit 227 based on the image formation conditions.

In addition to an adjustment chart where only the adjustment image is printed on a sheet, the adjustment image may also be printed on the periphery of a sheet on which an image corresponding to the print job is printed. When an adjustment image is printed on the periphery, the sheet is cut by the finisher 109 at the periphery where the adjustment image is printed. The following explanation will focus on the case where an adjustment chart is used.

The adjustment chart is removed so as not to be mixed in with the printed material corresponding to the print job. To this end, the printing device 107 is equipped with a flapper 324, a discharge path 326, a transport sensor 327, and a discharge tray 328. The adjustment chart, from which the adjustment image has been read by the CISs 321 and 322, is transported to the discharge path 326 by the flapper 324. The sheet transported to the discharge path 326 is discharged to the discharge tray 328.

If the sheet is not an adjustment chart, the sheet is transported from the transport path 323 to the downstream transport path 325 by the flapper 324. The sheet transported to the downstream transport path 325 is delivered to the finisher 109. Note that when the printing device 107 receives a notification from the finisher 109 that a transport jam has occurred, it switches the flapper 324 to the discharge path 326 side, regardless of whether the sheet is an adjustment chart or not, and discharges all sheets (residual paper) within the machine to the discharge tray 328. Discharging the residual paper to the discharge tray 328 reduces the burden on the user of clearing the jam.

The finisher 109 can stack sheets delivered from the printing device 107. The finisher 109 has a transport path 331 and a stack tray 332 for stacking sheets. Transport sensors 333, 334, 335, and 336 are provided on the transport path 331. Sheets transported from the printing device 107 are stacked on the stack tray 332 via the transport path 331. The transport sensors 333, 334, 335, and 336 detect the passage of a sheet transported along the transport path 331. If the transport sensors 333, 334, 335, and 336 do not detect the leading or trailing edge of the sheet in the transport direction within a predetermined time after the start of sheet transport, the CPU 242 determines that a transport jam (transport abnormality) has occurred within the finisher 109. In this case, the CPU 242 notifies the printing device 107 that a transport jam has occurred.

(How to set automatic adjustment)
The image forming apparatus 101 of this embodiment is capable of setting automatic adjustment, which automatically adjusts image formation conditions during printing. Fig. 5 is a diagram showing an example of a setting screen for setting the automatic adjustment. The setting screen is displayed on the display 225 by the CPU 222. The user can set the automatic adjustment from the setting screen using the operation unit 224. The user sets the automatic adjustment before issuing a command to execute printing.

Figure 5(a) shows the initial screen. When the user selects the soft key "Advanced Mode" from the initial screen, the CPU 222 displays the advanced mode selection screen of Figure 5(b) on the display 225. When the user selects the soft key "Adjust" from the advanced mode selection screen, the CPU 222 displays the automatic adjustment setting screen of Figure 5(c) on the display 225. When the user selects the soft key "Set" from the automatic adjustment setting screen, the CPU 222 displays the adjustment frequency selection screen of Figure 5(d) on the display 225.

When the user selects the "Adjustment Interval" soft key from the adjustment frequency selection screen, the CPU 222 displays the adjustment interval setting screen shown in Figure 5(e) on the display 225. Automatic adjustment is enabled when the user enters the number of sheets using the numeric keypad on the adjustment interval setting screen and presses the "OK" soft key. In the example of Figure 5(e), the number of sheets for the adjustment interval is set to 10. An adjustment chart is created for each number of sheets set in the adjustment interval. In other words, automatic adjustment is performed for each number of sheets set in the adjustment interval, and the image formation conditions are adjusted. Note that automatic adjustment is disabled when the user selects the "Cancel" soft key from the automatic adjustment setting screen.

When automatic adjustment is set, the CPU 222 displays an initial screen on the display 225. Figure 5 (f) shows the display 225 with the initial screen displayed, which includes a print button 601 and an interrupt button 602. When the user presses the print button 601, the CPU 222 executes printing. If automatic adjustment is enabled, the CPU 222 creates an adjustment chart for every number of sheets set in the adjustment interval. If automatic adjustment is disabled, no adjustment chart is created.

Automatic adjustment can also be set for interrupt print jobs, which are interrupt processes. An interrupt print job is set by the user pressing the interrupt button 602 during printing. After pressing the interrupt button 602, the user enables automatic adjustment, sets the adjustment interval to a specified number of sheets (for example, five sheets), and presses the print button 601. This creates an adjustment chart every five sheets during printing by the interrupt print job, and automatic adjustment is performed.

Figure 5(g) shows the paper feed stage selection screen. Details will be described later, but the CPU 222 displays the paper feed stage selection screen on the display 225 when automatic adjustment is performed for an interrupt print job. The user can use the paper feed stage selection screen to select the paper feed stage that will feed the sheets used for the adjustment chart.

(Information when a print job is executed)
6 is a diagram showing an example of job information stored in memory 223 when a print job is executed. The job information is stored in memory 223 by CPU 222 in response to input of a print job or an interrupt print job.

Job information is managed by job ID. Job information includes the paper feed deck ID, the number of sheets in the adjustment interval, the automatic adjustment flag, the interrupt printing flag, and the previous job ID. The paper feed deck ID indicates the paper feed deck that will feed sheets for the print job. The number of sheets in the adjustment interval is the number set on the adjustment interval setting screen. The automatic adjustment flag indicates the setting status of automatic adjustment. For example, if automatic adjustment is enabled, the automatic adjustment flag is set to "1", and if it is disabled, the automatic adjustment flag is set to "0". The interrupt printing flag indicates whether the job is an interrupt printing job. For example, if it is an interrupt printing job, the interrupt printing flag is set to "1", and if it is not an interrupt printing job, the interrupt printing flag is set to "0". If the job is an interrupt printing job, the previous job ID is the job ID of the print job that was executed before the interrupt.

The image formation conditions adjusted by automatic adjustment are set for each paper feed deck. The image formation conditions for each paper feed deck are stored in memory 223, for example, as automatic adjustment information. Figure 7 is an example diagram of automatic adjustment information. In this embodiment, we will explain the case where image density adjustment is performed by automatic adjustment.

The automatic adjustment information for each paper feed deck is identified by the paper feed deck ID. The automatic adjustment information includes an image density offset value, which is an adjustment value for the image density for each color, for each paper feed deck. The image density offset value is an adjustment value for adjusting (offsetting) the image density of the image to be printed. The CPU 222 reads out the automatic adjustment information at the start of the print process. For example, in the case of a job in which sheets are fed from paper feed deck 301 (first paper feed deck), the CPU 222 reads out the image density offset value for each color of the first paper feed deck ID 701 as the adjustment value. That is, the CPU 222 reads out the image density offset value Y 702, image density offset value M 703, image density offset value C 704, and image density offset value K 705. The CPU 222 adjusts the image formation conditions based on the read adjustment value for each color, and adjusts the image density of each color.

The image density offset values Y, M, C, and K for each paper feed deck are updated after the adjustment image is read. In other words, these adjustment values are updated based on the results of reading the adjustment image.

Figure 8 is an example diagram of an adjustment chart. When automatic adjustment is enabled, an adjustment image is printed on a sheet for each number of sheets set in the adjustment interval to create an adjustment chart. The adjustment image is composed of multiple (10 in this case) patch images with different image densities (gradations) arranged in a line for each color. The patch images at both ends of the line have the same image density, which is the maximum image density. The adjustment images are arranged for each color near the edge of the sheet. In this embodiment, cyan and magenta patch images are printed near one edge of the sheet, and yellow and black patch images are printed near the edge opposite that edge.

The adjustment image on the front side of the adjustment chart is read by CIS 321, and the adjustment image on the back side is read by CIS 322. CPU 222 acquires the density values of the image density of each color based on the results of reading the adjustment chart by CIS 321 and 322. CPU 222 determines the image density offset value based on the acquired density values of the image density of each color. CPU 222 updates the automatic adjustment information in memory 223 with the determined image density offset value. For example, if the adjustment chart is created using sheets fed from paper feed deck 301 (first paper feed deck), CPU 222 updates image density offset value Y702 to image density offset value K705 with the determined image density offset value.

(Printing process)
FIG. 9 is a flowchart illustrating the printing process. The CPU 222 acquires a print job and starts the printing process. In this embodiment, the paper feed deck 301 contains sheets (e.g., plain paper) with a minimally textured surface on which the image reading unit 231 (CIS 321, 322) can read a printed adjustment image with high accuracy. The paper feed deck 302 contains sheets (e.g., embossed paper) with a rough surface on which the image reading unit 231 (CIS 321, 322) cannot read a printed adjustment image with high accuracy. Note that, although embossed paper is used here as a representative example of a sheet on which the image reading unit 231 (CIS 321, 322) cannot read an adjustment image with high accuracy, the sheet is not limited to embossed paper as long as it is a type of sheet on which the image reading unit 231 (CIS 321, 322) cannot read with high accuracy. For example, sheets with textured surfaces are not limited to embossed paper and are sheets on which the image reading unit 231 (CIS 321, 322) cannot read with high accuracy. The multi-tray paper feed stage 300 holds (stores) sheets (for example, cardboard) with a surface that is minimally uneven and on which the image reading unit 231 (CIS 321, 322) can read a printed image for adjustment with high accuracy.

When the CPU 222 starts printing processing, it acquires job information corresponding to the print job (S901). The CPU 222 determines whether automatic adjustment for the print job is enabled based on the automatic adjustment flag included in the acquired job information (S902). If automatic adjustment is disabled (S902: N), the CPU 222 performs normal image formation processing (automatic adjustment disabled job) that does not include automatic adjustment operations (S911).

If automatic adjustment is enabled (S902: Y), the CPU 222 determines whether the sheet type set in the print job is embossed paper (S903). If it is not embossed paper (S903: N), the CPU 222 performs normal image formation processing (job with automatic adjustment enabled and no paper feed stage switching) including automatic adjustment operations (S910). If it is embossed paper (S903: Y), the CPU 222 determines whether automatic adjustment will be performed in an interrupt print job (S904). An interrupt print job occurs when the "Adjustment Interval" soft key is selected on the adjustment frequency selection screen in Figure 5(d). An interrupt print job occurs for every number of sheets set on the adjustment interval setting screen in Figure 5(e).

If automatic adjustment is not performed for an interrupt print job (S904: N), the CPU 222 performs normal image formation processing (job with automatic adjustment enabled and no paper feed stage switching) including automatic adjustment operations (S910). If automatic adjustment is performed for an interrupt print job (S904: Y), the CPU 222 displays the paper feed stage selection screen shown in FIG. 5(g) on the display 225 (S905). Because automatic adjustment using embossed paper reduces adjustment accuracy, automatic adjustment using other types of sheets is recommended. For this reason, the paper feed stage selection screen displays other paper feed stages that contain sheets that can be used for automatic adjustment. In this embodiment, the paper feed stage selection screen displays the paper feed deck 301 and the multi-tray paper feed stage 300 as paper feed stages that contain sheets that can be used for automatic adjustment.

The user selects one of the soft keys "Multi-tray," "First paper feed deck," or "No adjustment" from the paper feed stage selection screen and presses "OK." Pressing "OK" causes the CPU 222 to acquire the selection made on the paper feed stage selection screen. If "Multi-tray" or "First paper feed deck" is selected (S906: Y), the CPU 222 determines that another paper feed stage has been selected. In this case, the CPU 222 performs image formation processing including automatic adjustment with paper feed stage switching (job with paper feed stage switching and automatic adjustment enabled) (S907). If "No adjustment" is selected (S906: N), the CPU 222 determines that another paper feed stage has not been selected. In this case, the CPU 222 cancels the automatic adjustment setting and performs normal image formation processing (job with automatic adjustment disabled) (S911).

Note that the content of the paper feed tray selection screen in Figure 5(g) is not limited to this, and any screen that allows the user to select a paper feed tray may be used. Furthermore, the paper feed tray selection screen may be configured to eliminate the "Do not adjust" option and always require the user to select another paper feed tray.

After printing an image on a sheet through the process of S907, S910, or S911, the CPU 222 performs a process to determine whether the print job has ended (S908). The CPU 222 makes this determination based on whether printing of all pages specified in the print job has ended. If the result of the print job end determination process is that the print job has not ended (S908: N), the CPU 222 repeats the process from S901 onwards until the print job has ended. If the print job has ended (S908: Y), the CPU 222 ends the print process.

(Job with paper feed stage switching and automatic adjustment enabled)
FIG. 10 is a flowchart showing a job in which the automatic adjustment is enabled and the paper feed stage is switched in step S907.

The CPU 222 references the adjustment values set in the automatic adjustment information for the paper feed deck based on the paper feed deck ID included in the job information acquired in S901 (S1001). The CPU 222 determines the adjustment values based on the referenced automatic adjustment information (S1002). That is, the CPU 222 determines the adjustment values from the image density offset values Y 702, 707, 712, image density offset values M 703, 708, 713, image density offset values C 704, 709, 714, and image density offset values K 705, 710, 715.

The CPU 222 determines whether it is the beginning of the print job (S1003). If it is the beginning of the print job (S1003: Y), the CPU 222 switches the paper feed tray and starts the automatic adjustment operation before starting printing (S1005). If it is not the beginning of the print job (S1003: N), the CPU 222 determines that it is in the printing state and determines whether the number of sheets corresponding to the adjustment interval has been printed (S1004). If the number of sheets corresponding to the adjustment interval has been printed while in the printing state (S1004: Y), the CPU 222 switches the paper feed tray and starts the automatic adjustment operation (S1005).

In the processing of S1005, for example, if "Multi-tray" was selected from the paper feed tray selection screen in the processing of S906, the CPU 222 switches the paper feed tray for sheets to the multi-tray paper feed tray 300. The CPU 222 starts the automatic adjustment operation using sheets fed from the multi-tray paper feed tray 300. If "First paper feed deck" was selected from the paper feed tray selection screen in the processing of S906, the CPU 222 switches the paper feed tray to the paper feed deck 301 and starts the automatic adjustment operation using sheets fed from the paper feed deck 301.

The CPU 222 creates an adjustment chart by printing an adjustment image on a sheet fed from the switched paper feed tray (S1006). The CPU 222 reads the adjustment image from the adjustment chart using the image reading unit 231 (CIS 321, 322) (S1007). The CPU 222 acquires image density adjustment values based on the read result of the adjustment image (read image). The CPU 222 updates the adjustment values of the automatic adjustment information for the paper feed tray set in the print job using the acquired adjustment values (S1008). That is, the CPU 222 acquires image density offset value Y, image density offset value M, image density offset value C, and image density offset value K based on the read image. The CPU 222 updates the adjustment values for the paper feed tray set in the print job using the acquired image density offset value Y, image density offset value M, image density offset value C, and image density offset value K.

Then, the CPU 222 switches the sheet feed tray to the one set for the print job (S1009). The CPU 222 resets the count value L of the number of printed sheets to 0 and ends this process (S1010).

Note that if the number of printed sheets during printing is less than the adjustment interval (S1004: N), the CPU 222 performs normal image printing (S1011). After printing the image, the CPU 222 adds 1 to the count value L of the number of printed sheets and ends the process (S1212). In this way, a job with paper feed stage switching and automatic adjustment enabled is performed.

When automatic adjustment is enabled in this way and a print job is executed to print an image using embossed paper, the sheet used for the adjustment chart is switched to a sheet other than embossed paper and automatic adjustment is performed. The sheet other than embossed paper is selected by the user. In this case, the user selects a paper feed tray that contains a type of sheet other than embossed paper, and automatic adjustment is performed using a sheet other than embossed paper. As a result, automatic adjustment is performed without using a type of sheet, such as embossed paper, on which it is difficult for the image reading unit 231 to read images with high accuracy, making it possible to adjust image formation conditions with high accuracy.

(job with no paper feed stage switching and automatic adjustment enabled)
11 is a flowchart showing the automatic adjustment enabled job without paper feed stage switching in S910. This process is a normal automatic adjustment enabled job.

The CPU 222 determines the adjustment value (S1101, S1102) in the same manner as in the processes of S1001 and S1002 in FIG. 10S. The CPU 222 determines whether printing has been performed on the number of sheets corresponding to the adjustment interval (S1103). If printing has been performed on the number of sheets corresponding to the adjustment interval (S1103: Y), the CPU 222 starts the automatic adjustment operation.

When the automatic adjustment operation begins, the CPU 222 creates an adjustment chart by printing an adjustment image on a sheet fed from the paper feed tray set in the print job (S1104). The CPU 222 reads the adjustment image from the adjustment chart using the image reading unit 231 (CIS 321, 322) (S1105). The CPU 222 acquires image density adjustment values based on the read result of the adjustment image (read image). The CPU 222 updates the adjustment values in the automatic adjustment information for the paper feed tray set in the print job using the acquired adjustment values (S1106). That is, the CPU 222 acquires image density offset value Y, image density offset value M, image density offset value C, and image density offset value K based on the read image. The CPU 222 updates the adjustment values for the paper feed tray set in the print job using the acquired image density offset value Y, image density offset value M, image density offset value C, and image density offset value K. The CPU 222 then resets the count value L of the number of printed sheets to 0 and ends this process (S1107).

If printing has not been performed on the number of sheets corresponding to the adjustment interval (S1103: N), the CPU 222 performs normal image printing (S1108). After printing the image, the CPU 222 adds 1 to the count value L of the number of printed sheets and ends the process (S1109). In this way, the job with automatic adjustment enabled and no paper feed stage switching is performed.

(Automatic adjustment disabled job)
FIG. 12 is a flowchart showing the automatic adjustment invalidation job in S911.

If automatic adjustment is disabled, the CPU 222 references the automatic adjustment information for the paper feed deck based on the paper feed deck ID included in the job information acquired in S901 (S1201). The CPU 222 determines the adjustment values (image density offset value Y, image density offset value M, image density offset value C, image density offset value K) based on the referenced automatic adjustment information (S1202). The CPU 222 prints an image corresponding to the print job on a sheet under image formation conditions based on the determined adjustment values (S1203). The automatic adjustment disabled job is performed in this manner.

As described above, in this embodiment, if automatic adjustment is difficult due to the influence of the surface properties of the sheet used for the adjustment chart, the adjustment chart is switched to a type of sheet that is less affected by other surface properties and automatic adjustment is performed. In other words, if the surface properties of the sheet used in the print job are unsuitable for high-precision automatic adjustment, a sheet with a smoother surface is used for the adjustment chart. This makes it possible to adjust image density with high precision using a simple method, regardless of the surface properties of the sheet. In this embodiment, we have described a case where image density is adjusted automatically, but this embodiment is also effective when performing other automatic adjustments, such as adjusting geometric characteristics.

In the above example, if the sheet used to create the adjustment chart is not suitable for automatic adjustment, the adjustment chart is created using a sheet fed from the paper feed tray selected by the user on the paper feed tray selection screen. The alternative sheet may be selected by the user or automatically by the image forming apparatus 101.

In this case, the image forming apparatus 101 has the type of sheets (name, surface properties, etc.) stored in each of the multiple paper feed trays registered in memory 223 in advance. When the CPU 222 interrupts a print job to perform automatic adjustment, it checks the sheet type (or paper feed tray) specified in the print job. If the check shows that the sheet type is not suitable for automatic adjustment, the CPU 222 checks the registered contents of memory 223 to check the sheet types stored in the other paper feed trays. If the other paper feed trays contain sheets suitable for automatic adjustment, an adjustment chart is created using sheets fed from that paper feed tray. If the other paper feed trays do not contain sheets suitable for automatic adjustment, automatic adjustment is disabled.

Claims (13)

an image forming means for forming an image on a sheet based on image forming conditions;
a reading means for reading the adjustment image formed on the sheet;
an adjusting unit that adjusts the image forming conditions based on the result of reading the adjustment image by the reading unit;
a control unit that controls the image forming unit to form the adjustment image on a sheet while a print job for forming a plurality of images on a plurality of sheets is being executed by the image forming unit, and controls the adjustment unit to adjust the image forming conditions based on the result of reading the adjustment image by the reading unit,
the control means, when the plurality of sheets are sheets of a first type, causes the adjustment image to be formed on a sheet of a second type different from the first type.
Image forming device. the reading means is capable of reading the adjustment image formed on the second type of sheet with higher accuracy than the adjustment image formed on the first type of sheet,
2. The image forming apparatus according to claim 1. the control means can perform the adjustment with high accuracy by using a reading result of the adjustment image of the adjustment chart formed on the second type of sheet rather than a reading result of the adjustment image of the adjustment chart formed on the first type of sheet.
2. The image forming apparatus according to claim 1. further comprising a plurality of paper feed trays for accommodating different types of sheets;
the image forming unit forms an image on a sheet fed from one of the plurality of paper feed stages,
the control unit feeds sheets from a sheet feed tray that accommodates the first type of sheets when printing according to the print job, and feeds sheets from a sheet feed tray that accommodates the second type of sheets when performing the adjustment to create an adjustment chart.
2. The image forming apparatus according to claim 1. the control unit displays a selection screen on a display for selecting a paper feed tray that stores sheets used to create an adjustment chart when performing the adjustment by interrupting printing of the print job.
5. The image forming apparatus according to claim 4. The selection screen allows a user to select a paper feed tray that contains sheets that can be used for the adjustment.
6. The image forming apparatus according to claim 5. the control unit creates the adjustment chart using sheets stored in a paper feed tray selected from the selection screen.
7. The image forming apparatus according to claim 5. The selection screen allows a user to select a paper feed tray containing sheets that can be used for the adjustment, or to disable the adjustment,
the control means invalidates the adjustment when invalidation of the adjustment is selected on the selection screen.
6. The image forming apparatus according to claim 5. The printer further includes a registration unit for registering the types of sheets stored in the plurality of paper feed trays,
the control means, when interrupting the print job to perform the adjustment, checks the type of the first type of sheet, and if the first type of sheet is the first type, checks the type of other sheet by referring to the registration means, and if there is a paper feed tray that stores the second type of sheet, creates the adjustment chart using the sheet in that paper feed tray as the second type of sheet.
5. The image forming apparatus according to claim 4. the control unit disables the adjustment if there is no paper feed tray that accommodates the second type of sheets.
10. The image forming apparatus according to claim 9. The surface of the second type of sheet is smoother than the surface of the first type of sheet.
2. The image forming apparatus according to claim 1. The first type of sheet is a sheet having a textured surface.
The image forming apparatus according to claim 11. The first type of sheet is embossed paper.
The image forming apparatus according to claim 12.