Image forming device

Abstract

To provide an image forming apparatus that, in forming images with a priority on image quality, improves productivity while maintaining the image quality.SOLUTION: An image forming apparatus can form images on a sheet at a plurality of image forming speeds. The image forming apparatus holds, in a RAM 203 for every type of the sheet, information on a first image forming speed when forming images in a productivity priority mode, and a second image forming speed when forming images in an image quality priority mode. The RAM 203 also stores a setting value for changing the image forming speed when the image forming apparatus operates in the image quality priority mode. The image forming apparatus operates in the productivity priority mode, it forms images at the first image forming speed according to the type of the sheet, and when the image forming apparatus operates in the image quality priority mode, it forms images at a speed obtained by changing, according to the setting value, the second image forming speed according to the type of the sheet.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, such as a copying machine, a printer, or a facsimile machine, that forms an image on a sheet of paper. [Background technology]

[0002] Image forming apparatuses are required to be highly productive and multimedia-compatible, capable of printing images on various types of paper, including thin paper, thick paper, and coated paper (e.g., gloss coated paper, matte coated paper, etc.). The heavier the paper's basis weight, the more heat must be applied to the paper when fixing the image transferred onto it. Generally, the image formation speed is set slower to increase the amount of heat applied per unit area of ​​the paper. To achieve this, image forming apparatuses are capable of operating at multiple image formation speeds tailored to the basis weight and surface properties of the paper. The image formation speed refers to the operating speed of image forming units, such as the photosensitive drum, developing unit, and intermediate transfer belt (discussed below), the paper transport speed when transferring an image to the paper, and the paper transport speed when fixing the toner on the paper.

[0003] The points that users prioritize may differ depending on the output. For example, when printing reports such as documents, many users prioritize maximizing productivity over image quality, while when printing images such as photographs, many users prioritize maximizing image quality over productivity. The image forming device in Patent Document 1 allows users to select between a productivity-priority mode, which provides a faster image formation speed while keeping image quality within a predetermined range, and an image quality-priority mode, which provides an image formation speed that maximizes image quality (Patent Document 1). Images are printed at an image formation speed that corresponds to the operating mode selected by the user. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-15419 Summary of the Invention [Problem to be solved by the invention]

[0005] Image forming devices for commercial printing handle a wide variety of paper types. As a result, even paper with the same basis weight can have significantly different characteristics. For example, one paper characteristic is its stiffness. Also known as paper stiffness, stiffness is an indicator of the resistance of paper when it is bent. High stiffness increases the impact the paper exerts on the transfer section, which transfers the image onto the paper. This can cause unevenness in the image transferred to the paper. In this case, slowing down the speed at which the paper enters the transfer section (image formation speed) can reduce the impact and mitigate the cause of unevenness in the image.

[0006] The image quality priority mode is a mode in which images are formed at the highest image quality level regardless of the characteristics of the paper, as long as the paper has the same basis weight. Therefore, the image formation speed is set to match the image formation speed for the paper with the highest stiffness. The image formation speed for the paper with the highest stiffness is slower than the image formation speed for other types of paper. This means that even if a faster image formation speed can be set for other types of paper with lower stiffness, a slower image formation speed is set. Therefore, in the image quality priority mode, images are formed at a slow image formation speed regardless of the characteristics of the paper, making it difficult to increase productivity.

[0007] SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is a primary object of the present invention to provide an image forming apparatus that improves productivity while maintaining image quality when forming images with priority given to image quality. [Means for solving the problem]

[0008] The image forming apparatus of the present invention includes a plurality of operation Selected from the mode operation An image forming apparatus that forms an image on a sheet based on a mode, an image forming unit having a photosensitive member that is driven to rotate, a charging unit that charges the photosensitive member, an exposure unit that exposes the photosensitive member to light in order to form an electrostatic latent image on the photosensitive member charged by the charging unit, a development unit that develops the electrostatic latent image, an intermediate transfer member to which the image developed by the development unit is transferred, and a transfer unit that presses the intermediate transfer member to form a transfer nip and transfers the image on the intermediate transfer member to the paper that passes through the transfer nip; a control unit that controls the rotation speed of the photosensitive member, the rotation speed of the intermediate transfer member, and the transport speed of the paper that passes through the transfer nip based on an image formation speed; and the operation modes include an image quality priority mode that prioritizes the image quality of an image formed by the image forming device, and a productivity priority mode in which the image formation speed is faster than the image formation speed of the image quality priority mode, and The image forming speed is From the image forming speed corresponding to the type of paper a display means for displaying a screen for making the change; and the control means comprises: The image forming apparatus Prioritizing productivity When an image is formed based on the mode, Productivity firstFirst data for the mode and the type of paper determining an imaging speed; controlling the rotation speed of the photosensitive member based on the determined image formation speed; The image forming apparatus Image quality priority When forming an image based on the mode, If the paper on which the image is to be formed is a paper on which the image forming speed has not been changed, the image quality priority Secondary data for the mode and the type of paper Determine the image formation speed and controls the rotation speed of the photosensitive member based on the determined image formation speed, and when the image forming apparatus forms an image based on the image quality priority mode, if the paper on which the image is to be formed is a paper for which the image formation speed has been changed, controls the rotation speed of the photosensitive member based on the changed image formation speed. It is characterized by: [Effects of the Invention]

[0009] According to the present invention, when forming an image with priority given to image quality, it is possible to perform an image forming operation with improved productivity while maintaining image quality. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus. [Figure 2] FIG. [Figure 3] 10(a) and 10(b) are explanatory diagrams of the operation unit. [Figure 4] FIG. [Figure 5] FIG. 4 is an explanatory diagram of image forming speed for each paper type. [Figure 6] FIG. 10 is a diagram showing an example of an operation mode selection screen. [Figure 7] FIG. 10 is a diagram showing an example of a paper registration screen. [Figure 8] 10 is a diagram showing an example of a paper type selection screen. [Figure 9] 10 is a view showing an example of a paper type selection screen when a new paper type is added. [Figure 10] FIG. 10 is a diagram showing an example of a paper setting change screen. [Figure 11] FIG. 10 is a diagram illustrating a basis weight setting screen. [Figure 12] FIG. 10 is a view showing an example of an image forming speed setting screen when image quality is prioritized. [Figure 13] 10 is a flowchart showing an image forming process. [Figure 14] 10 is a flowchart showing an image forming process. [Figure 15] 10 is a flowchart showing an image formation speed limiting process. [Figure 16]FIG. 10 is a diagram illustrating a table showing a limit range of an image forming speed. [Figure 17] FIG. 10 is a view showing an example of a setting screen for setting upper and lower limit values. [Figure 18] 10 is a flowchart showing a process for determining an upper limit value and a lower limit value. [Figure 19] 10 is a flowchart showing a display setting process for a paper setting change screen. [Figure 20] 10 is a flowchart showing a process for displaying a paper setting change screen. [Figure 21] FIG. 10 is a diagram illustrating a screen A for changing paper settings. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will now be described in detail by way of example with reference to the drawings.

[0012] (First embodiment) FIG. 1 is a configuration diagram of an image forming apparatus according to this embodiment. This image forming apparatus is an electrophotographic full-color image forming apparatus. The image forming apparatus includes a reader 1 and a printer 5. The reader 1 is provided on the housing of the printer 5. The reader 1 according to this embodiment is an image reading device that reads a color image from an original. The printer 5 according to this embodiment is a color printer that prints a color image on paper P. Such an image forming apparatus is, for example, a copier, a multifunction peripheral, or the like.

[0013] The reader 1 comprises a platen glass 2, a full-color sensor 3, and an image processing unit 4. A document on which an image to be read is printed is placed on the platen glass 2. The full-color sensor 3 is, for example, a CCD (Charge Coupled Device) image sensor. The full-color sensor 3 receives light reflected from the document and converts the received reflected light into an electrical signal (color separation image signal). The color separation image signal is subjected to image processing by the image processing unit 4 and sent to the printer 5.

[0014] Printer 5 has four image forming units (first to fourth image forming units UY, UM, UC, and UK) arranged in tandem. Each of the first to fourth image forming units UY, UM, UC, and UK is a laser exposure type electrophotographic process mechanism, and forms an image based on a color separation image signal sent from reader 1 during copying, for example. Printer 5 includes a primary transfer unit 6, an intermediate transfer belt 7, a secondary transfer unit 8, a fixing unit 12, a cassette paper feed mechanism 9, and a manual paper feed unit 11. A deck paper feed unit 10 is connected to printer 5.

[0015] Each of the first to fourth image forming units UY, UM, UC, and UK includes a photosensitive drum, a charger, an exposure unit, a developing unit, and the like. The photosensitive drum is a drum-shaped photosensitive body having a photosensitive layer on its surface. The charging unit uniformly charges the surface of the photosensitive drum. The exposure unit forms an electrostatic latent image on the surface of the photosensitive drum by irradiating the charged surface of the photosensitive drum with laser light modulated according to a color separation image signal of the corresponding color. The developing unit develops the electrostatic latent image with toner of the corresponding color, thereby forming a toner image on the photosensitive drum.

[0016] The first image forming unit UY forms a yellow toner image on the surface of the photosensitive drum. The second image forming unit UM forms a magenta toner image on the surface of the photosensitive drum. The third image forming unit UC forms a cyan toner image on the surface of the photosensitive drum. The fourth image forming unit UK forms a black toner image on the surface of the photosensitive drum. The first to fourth image forming units UY, UM, UC, and UK each form a toner image at their own timing.

[0017] The toner images formed on the photosensitive drums of the first to fourth image forming units UY, UM, UC, and UK are transferred in succession by the primary transfer unit 6 onto the intermediate transfer belt 7 in a superimposed state. As a result, a full-color toner image is formed by superimposing the four color toner images on the intermediate transfer belt 7. The intermediate transfer belt 7 conveys the full-color toner image to the secondary transfer unit 8 by rotating.

[0018] The paper P can be fed from a cassette paper feed mechanism 9, a manual paper feed unit 11, or a deck paper feed unit 10. The paper P is fed to the secondary transfer unit 8 from either the cassette paper feed mechanism 9, the manual paper feed unit 11, or the deck paper feed unit 10 depending on the timing of image formation by the first to fourth image forming units UY, UM, UC, and UK. The secondary transfer unit 8 transfers the full-color toner image carried by the intermediate transfer belt 7 all at once onto the fed paper P. The paper P with the transferred toner image is transported from the secondary transfer unit 8 to a fixing unit 12.

[0019] The fixing unit 12 sandwiches and transports the paper P onto which the toner image has been transferred in a fixing nip portion. During this sandwiching and transporting process, the unfixed toner image is melted and mixed by heat and pressure, and is fixed as a fixed image on the paper P. The paper P with the fixed image is discharged as a finished product to a face-up paper output tray 14 or a face-down paper output tray 15. A flapper 13 is arranged behind the fixing unit 12. The paper P is discharged by the flapper 13 to either the face-up paper output tray 14 or the face-down paper output tray 15.

[0020] When double-sided printing is performed, the paper P with an image formed on one side (first side) is first transported from the fixing device 12 to a transport path on the face-down paper output tray 15 side, and then switched back and transported to the re-conveying sheet path 16. This causes the printed side of the paper P to be reversed. The paper P is transported to the secondary transfer unit 8 via the re-conveying sheet path 16. Thereafter, in the same way as printing an image on the first side, a toner image is transferred to the second side of the paper P, which is different from the first side, and the image is fixed by the fixing device 12. In this way, an image is printed on the second side. The paper P with images printed on both sides is discharged to the face-up paper output tray 14 or the face-down paper output tray 15.

[0021] 2 is an explanatory diagram of a control unit that controls the operation of the image forming apparatus. The control unit 200 is an information processing device that includes a CPU (Central Processing Unit) 204, a ROM (Read Only Memory) 205, and a RAM (Random Access Memory) 203. The CPU 204 controls the overall operation of the image forming apparatus by executing computer programs stored in the ROM 205. The RAM 203 provides a working area for the CPU 204 when executing processing. In addition to the reader 1 and printer 5 described above, an operation unit 300 is also connected to the control unit 200. The control unit 200 is provided, for example, inside the housing of the printer 5.

[0022] The reader 1 transmits a color separation image signal to the control unit 200. The control unit 200 controls the operation of the printer 5 as described above in response to the color separation image signal, thereby printing an image on the paper P. The printer 5 operates the first to fourth image forming units UY, UM, UC, and UK, the secondary transfer unit 8, the fixing unit 12, etc. in response to instructions from the control unit 200, thereby performing the image formation process (printing process) as described above. As described above, the printer 5 includes a cassette paper feed mechanism 9, a deck paper feed unit 10, and a manual paper feed unit 11. In response to instructions from the control unit 200, the printer 5 feeds the paper P to be used for printing from either the cassette paper feed mechanism 9, the deck paper feed unit 10, or the manual paper feed unit 11. In response to instructions from the control unit 200, the printer 5 controls the transport speed of the paper P during feeding in response to instructions from the control unit 200.

[0023] 3 is an explanatory diagram of the operation unit 300. A user can input various image formation conditions and information into the image forming apparatus using the operation unit 300 to set them. The operation unit 300 is a user interface that includes an input interface and an output interface. The input interface includes various key buttons, a touch panel, etc. The output interface includes a display 301, a speaker, etc. The operation unit 300 is used to display print information, print progress information, etc., and to set various settings for the printer 5.

[0024] Fig. 3(a) is a plan view of the operation unit 300. The operation unit 300 is equipped with a display 301, a reset key 302, a start key 303, a stop key 304, a clear key 305, a numeric keypad 306, a color mode selection key 307, and a user mode key 308. Fig. 3(b) shows an example of a setting screen that is displayed on the display 301 when copying. On the setting screen when copying, it is possible to set the number of copies, selected paper size, magnification, copy density, etc.

[0025] The reset key 302 is used to reset settings, for example, returning the copy mode to the standard mode. The start key 303 is used, for example, to instruct the start of a copy operation. The stop key 304 is used, for example, to instruct the interruption of a copy operation. The clear key 305 is used, for example, to return the operation mode from the copy mode to the standard mode. The numeric keypad 306 is used, for example, to set numerical values ​​such as the number of copies. When the user mode key 308 is pressed, a selection screen, which will be described later, is displayed on the display 301.

[0026] The color mode selection keys 307 include an ACS key, a Color key, and a Black key. The ACS key is used to cause the reader 1 to automatically determine whether the image of the document being read is color or black and white, and to output a color image signal if the image is color, or a black and white image signal if the image is black and white. The Color key is used to cause the reader 1 to output a color image signal regardless of the image of the document. The Black key is used to cause the reader 1 to output a black and white image signal regardless of the image of the document. In this embodiment, the color mode selection keys 307 are configured so that any one key that is selected lights up.

[0027] (Image quality priority mode, Productivity priority mode) When a toner image transferred onto paper P is fixed by the fixing device 12, the amount of heat applied to paper P per unit time varies depending on the basis weight of the paper P, so an optimal image formation speed is set according to the basis weight of the paper P. Setting the basis weight for each paper P is cumbersome for the user. For this reason, the image forming device sets the same transfer conditions, fixing conditions, and paper conveyance speed (image formation speed) for each predetermined basis weight range. The aforementioned basis weight range is called a paper category. In the following example, paper P with a basis weight of 64 to 150 [gsm] is called "plain paper," paper P with a basis weight of 151 to 250 [gsm] is called "cardboard 1," and paper P with a basis weight of 251 to 350 [gsm] is called "cardboard 2."

[0028] FIG. 4 is an explanatory diagram of the image formation speed of the image forming apparatus. When the image formation speed is changed, the rotation speed of the photosensitive drum and the rotation speed of the intermediate transfer belt 7 are controlled to be rotation speeds based on the image formation speed. The image forming apparatus can operate at first to third image formation speeds. In this embodiment, the first speed is the fastest image formation speed and is 400 [mm / s]. The second speed is an image formation speed slower than the first speed and is 300 [mm / s]. The third speed is the slowest image formation speed and is 200 [mm / s].

[0029] In the productivity priority mode, which prioritizes productivity of the finished product, the image formation speed is set to the fastest speed at which an image can be formed. In the image quality priority mode, which prioritizes image quality of the finished product, the image formation speed is set to be slower than in the productivity priority mode. In the image quality priority mode, the finished image is printed with higher quality than in the productivity priority mode. The productivity priority mode and the image quality priority mode will be described below.

[0030] The productivity priority mode is an operating mode in which image formation is performed at the maximum possible image formation speed. In the productivity priority mode, image quality is kept within a predetermined range, maximizing productivity. The image quality priority mode is an operating mode in which image formation is performed at a slower image formation speed than the productivity priority mode in order to maximize the image quality of the image printed on the finished product. In the image quality priority mode, for example, the transport speed of the paper P when it enters the secondary transfer unit 8 is slowed down, thereby reducing the shock when the paper P enters the secondary transfer unit 8 and improving the transferred image quality. In addition, in the image quality priority mode, the transport speed of the paper P in the fixing unit 12 is slowed down, thereby applying more heat from the fixing unit 12 to the paper P and improving the glossiness.

[0031] FIG. 5 is an explanatory diagram of the image formation speed for each paper type in each operating mode (productivity priority mode, image quality priority mode). In FIG. 5, the paper types are plain paper, thick paper 1, and thick paper 2. The image formation speed is determined by the operating mode and paper type. For example, the image formation speed for plain paper is the first speed (400 mm / s) in productivity priority mode and the second speed (300 mm / s) in image quality priority mode. Because thick paper 1 and thick paper 2 both have a large paper basis weight, it is necessary to further reduce the shock when the paper enters the secondary transfer unit 8. For this reason, the image formation speed for thick paper 1 and thick paper 2 in image quality priority mode is the slowest, third speed (200 mm / s). The image formation speed for thick paper 1 in productivity priority mode is the first speed (400 mm / s). The image forming speed in the productivity priority mode for thick paper 2 is the second speed (300 mm / s) because a larger amount of heat needs to be applied to paper P from the fixing device 12 than to thick paper 1.

[0032] In this embodiment, the image formation speed is described for plain paper / thick paper with a high-quality surface. However, it is also possible to determine the image formation speed in a similar manner for paper such as coated paper. Furthermore, while the image formation speed for plain paper is set to the second speed in the image quality priority mode, it does not have to be the second speed as long as it is slower than the first speed. For example, it may be a third speed or a fourth speed that is different from the second and third speeds. In other words, the image formation speed may be set to more speeds than the first, second, and third speeds. While the image formation speed in the image quality priority mode is set to a slower speed than the image formation speed in the productivity priority mode, it may be the same speed depending on the basis weight of the paper. For example, for plain paper, the image formation speed in the image quality priority mode and the image formation speed in the productivity priority mode may be the same, the first speed.

[0033] 5 is stored in advance in the RAM 203 or the ROM 205. Based on this information, the CPU 204 determines the image formation speed during image formation and prints the image on the paper P.

[0034] (Operation mode selection) 6 is a diagram showing an example of an operation mode selection screen. The selection screen is displayed on the display 301 of the operation unit 300. The user can select an operation mode (productivity priority mode, image quality priority mode) from the selection screen using the input interface of the operation unit 300. Information indicating the selection result of the operation mode is stored in the RAM 203.

[0035] The selection screen in Figure 6 is displayed on the display 301 when the user mode key 308 is pressed. Before executing printing, the user selects either a selection button 601 for the productivity priority mode or a selection button 602 for the image quality priority mode from the selection screen using the operation unit 300. The control unit 200 acquires the selection from the operation unit 300 and sets the image forming apparatus to the selected operation mode. Information on the set operation mode is saved in the RAM 203.

[0036] When the productivity priority mode selection button 601 is selected, the image forming apparatus is able to form images on all sheets stored in all paper feed trays (cassette paper feed mechanism 9, manual paper feed unit 11, and deck paper feed unit 10) while maximizing productivity. When the image quality priority mode selection button 602 is selected, the image forming apparatus is able to form images on all sheets stored in all paper feed trays while maximizing image quality.

[0037] (Registering paper for each paper feed tray) The type and classification of paper P stored in each paper feed tray of the cassette paper feed mechanism 9, manual paper feed unit 11, and deck paper feed unit 10 are registered in the image forming apparatus. FIG. 7 is a view showing an example of a paper registration screen. The user selects the paper feed tray for registering paper using the operation unit 300 from the registration screen of FIG. 7 displayed on the display 301. The cassette paper feed mechanism 9 includes cassettes 1 to 4. By selecting a paper feed tray, it becomes possible to select the type of paper stored in the selected paper feed tray.

[0038] FIG. 8 is an example of a paper type selection screen that is displayed when a paper feed tray is selected. The control unit 200 saves a list of paper types that can be used in the image forming apparatus in RAM 203. A list of multiple paper types is saved for each paper classification that is pre-determined in the image forming apparatus. The user selects from this list the type of paper P stored in the cassette paper feed mechanism 9, deck paper feed unit 10, and manual paper feed unit 11, and presses the OK button. This completes the registration of paper for the paper feed tray selected in FIG. 7. The registered information is saved in RAM 203.

[0039] When using typical types of paper, the paper is registered as described above. However, in the case of image forming devices for commercial printing, there is a wide variety of paper types that can be handled, so pre-created paper settings may need to be changed. For this reason, it is important that the device is configured to allow the user to change paper settings.

[0040] When the user wants to change the paper settings, they select the paper type for which they want to change the settings from the paper type selection screen in Figure 8 and press the copy button. This creates new paper type information that copies the settings of the selected paper. Figure 9 is an example of the paper type selection screen when a new paper type is added. In this example, "Cardboard 1_Modified" is added, which is a copy of "Cardboard 1". Paper settings are made for the newly added paper type.

[0041] Fig. 10 is a diagram showing an example of a paper setting change screen. Paper settings are made on this change screen for newly added paper types. The paper setting change screen is displayed on the display 301 when the paper to be changed is selected from the selection screen of Fig. 9 using the operation unit 300. Paper settings include, for example, "basis weight," "transfer voltage," "fixing temperature," and "image formation speed when image quality is prioritized," but other paper-related settings may also be changeable.

[0042] "Basis Weight" is a button for changing the basis weight setting of the paper. Pressing the "Basis Weight" button displays a basis weight setting screen on the display 301, as shown in FIG. 11. The user can input the basis weight of the paper in gsm units using the numeric keypad 306. After inputting the basis weight, the user presses the OK button to set the basis weight of the paper.

[0043] "Transfer voltage" is a button for changing the setting of the voltage value when an image (toner image) is transferred to paper by the secondary transfer unit 8. Since the resistance value of paper varies depending on the type (brand), the transfer voltage needs to be adjusted for each brand. By pressing the "Transfer" button, a transfer voltage setting screen (not shown) is displayed on the display 301. The user can change the transfer voltage according to the characteristics of the paper. The transfer voltage is one of the parameters included in the image formation conditions.

[0044] "Fixing temperature" is a button for changing the temperature (fixing temperature) of the fixing device 12 when fixing a toner image to paper. Since the thickness of paper varies depending on the type (brand), the amount of heat required to fix an image varies depending on the type of paper. For this reason, the fixing temperature can be adjusted. By pressing the "Fixing" button, a fixing temperature setting screen (not shown) is displayed on the display 301. The user can change the fixing temperature depending on the characteristics of the paper. The fixing temperature is one parameter included in the image formation conditions.

[0045] "Image formation speed when image quality is prioritized" is a button for changing the image formation speed in image quality priority mode. When the "Image formation speed when image quality is prioritized" button is pressed, an image formation speed setting screen for image quality priority mode, as shown in FIG. 12, is displayed on the display 301. The user can change the image formation speed in image quality priority mode from the preset default speed by pressing the "+" button or the "-" button using the numeric keypad 306. When the "+" button is pressed, the image formation speed in image quality priority mode is changed to a speed faster than the default speed. When the "-" button is pressed, the image formation speed in image quality priority mode is changed to a speed slower than the default speed.

[0046] The result of changing the image formation speed when image quality is prioritized by pressing the "+" or "-" button is displayed as a setting value (-2 / -1 / 0 / +1 / +2) on the screen in Fig. 12. The user sets the image formation speed when image quality is prioritized by checking the displayed setting value and pressing the OK button.

[0047] For example, if the basis weight of the paper P is 180 [gsm], the control unit 200 sets the image formation speed in the image quality priority mode to the default of 200 [mm / s] based on FIG. 5. Therefore, if "0" is displayed as the setting value on the screen in FIG. 12, the image formation speed in the image quality priority mode will be 200 [mm / s]. Also, if the "+" button is pressed once in FIG. 12 (if the setting value is +1), the image formation speed in the image quality priority mode will be 300 [mm / s], which is one step faster than the default speed, based on FIG. 4. If the "+" button is pressed twice in FIG. 12 (if the setting value is +2), the image formation speed in the image quality priority mode will be 400 [mm / s], which is two steps faster than the default speed, based on FIG. 4.

[0048] As described above, each item is changed on the paper setting change screen in Fig. 10. After changing each item, the user presses the OK button. When the OK button is pressed, the control unit 200 saves the input settings for each item in RAM 203 as paper settings for the copied paper type. In this way, the copied paper type is added to the paper list.

[0049] (Image formation speed determination process) 13 is a flowchart showing an image formation process including a process for determining an image formation speed. In this process, an image formation speed in the productivity priority mode and an image formation speed in the image quality priority mode are determined. Image formation is performed at the determined image formation speed.

[0050] The user presses the start key 303 on the operation unit 300 to instruct the control unit 200 (CPU 204) to start a job. To do this, the control unit 200 waits for the start of the job until the start key 303 is pressed (S101: N). When the user presses the start key 303 on the operation unit 300, the control unit 200 starts the job (S101: Y). The control unit 200 acquires the paper settings set for the paper feed tray that stores the paper P to be used in the image forming operation (S102). The control unit 200 checks the "basis weight" of the paper P based on the paper settings, and determines the paper classification shown in FIG. 5 according to the basis weight (S103).

[0051] The control unit 200 determines whether the operation mode is the productivity priority mode or not (S104) by referring to the operation mode stored in the RAM 203. If the operation mode is the productivity priority mode (S104: Y), the control unit 200 determines the image formation speed in the productivity priority mode using the table shown in Fig. 5 based on the paper classification determined in the process of S103 (S105).

[0052] If the operating mode is the image quality priority mode (S104: N), the control unit 200 checks the setting value of "image formation speed in image priority mode" included in the paper settings acquired in the process of S102 (S111). The control unit 200 determines whether the acquired setting value is "0" (S112). If the setting value is "0" (S112: Y), the control unit 200 determines the image formation speed in the image quality priority mode using the table shown in FIG. 5 based on the paper classification determined in the process of S103 (S113).

[0053] If the set value is not "0" (S112: N), the control unit 200 selects the default image formation speed (S121), similar to the process of S113. The control unit 200 determines the image formation speed in the image quality priority mode by offsetting the selected image formation speed according to the set value (S122).

[0054] After determining the image formation speed through the process of S105, S113, or S122, the control unit 200 starts the image formation operation using the transfer voltage and fixing temperature based on the paper settings acquired through the process of S102 and the determined image formation speed (S106). As a result, the image forming device forms an image on the paper P to generate a product.

[0055] The control unit 200 repeats the processes from S102 to S106 until the final page specified in the job (S107: N). The control unit 200 repeats the processes from S102 to S106 until the final page specified in the job, and ends the process when it outputs the final page of the deliverable (S107).

[0056] In the above process, the operation mode is determined for each page, but the operation mode may be stored in the RAM 203 at the start of a job, and the stored contents may be referenced when processing is performed.

[0057] The image forming apparatus of this embodiment can operate in a productivity-priority mode and an image quality-priority mode, and the image formation speed is determined based on the paper type and the operating mode. The image formation speed in the image quality-priority mode can be changed (adjusted). Therefore, even when image quality is the priority, image formation can be performed at an image formation speed appropriate for the paper, enabling image formation with improved productivity while maintaining image quality.

[0058] (Second embodiment) The image forming apparatus and control unit of the second embodiment have the same configuration as the image forming apparatus and control unit 200 of the first embodiment, and therefore a description thereof will be omitted. Below, differences from the image forming apparatus of the first embodiment will be described.

[0059] In the first embodiment, the image formation speed in the image quality priority mode can be changed by the user. This allows the image formation speed intended by the user to be realized, but depending on the setting value, there is a possibility that the image formation speed may be set such that image quality cannot be guaranteed. To prevent this, the following operation is performed in the second embodiment.

[0060] 14 is a flowchart showing the image formation process including the process of determining the image formation speed according to the second embodiment. The control unit 200 (CPU 204) determines the image formation speed by the same processes as S101 to S105, S111 to S113, S121, and S122 in FIG. 13 (S901 to S905, S911 to S913, S921, and S922). In addition, when the operating mode is image quality priority mode and the image formation speed is offset by the set value (S922), the control unit 200 performs the image formation speed limiting process described below and sets the offset image formation speed to a speed within a predetermined limit range (S923).

[0061] After determining the image formation speed, the control unit 200 starts the image formation operation using the transfer voltage and fixing temperature based on the paper settings acquired in the process of S902 and the determined image formation speed (S906). As a result, the image forming device forms an image on the paper P to generate a deliverable.

[0062] The control unit 200 repeats the processes from S902 to S906 until the final page specified in the job (S907: N). The control unit 200 repeats the processes from S902 to S906 until the final page specified in the job, and ends the process when it outputs the final page of the deliverable (S907).

[0063] In the above process, the operation mode is determined for each page, but the operation mode may be stored in the RAM 203 at the start of a job, and the stored contents may be referenced when processing is performed.

[0064] Fig. 15 is a flowchart showing the image formation speed limiting process of S923. Fig. 16 is an example of a table showing the image formation speed limit range according to basis weight (paper type). The image formation speed limit range is set by an upper limit speed and a lower limit speed for each paper type. The table of Fig. 16 is stored in RAM 203.

[0065] When the control unit 200 starts the image formation speed limiting process, it checks the type of paper P used for image formation. The control unit 200 determines whether the type of paper P is set to plain paper (basis weight 64 to 150 [gsm]) (S1201). If plain paper is set (S1201: Y), the control unit 200 sets the upper limit speed X of the image formation speed to upper limit speed 1 (FIG. 16) and sets the lower limit speed Y to lower limit speed 1 (FIG. 16) (S1202).

[0066] If plain paper is not set (S1201: N), the control unit 200 determines whether the type of paper P is set to cardboard 1 (basis weight 151 to 250 [gsm]) (S1203). If cardboard 1 is set (S1203: Y), the control unit 200 sets the upper limit speed X of the image forming speed to upper limit speed 2 (FIG. 16) and sets the lower limit speed Y to lower limit speed 2 (FIG. 16) (S1204).

[0067] If thick paper 1 is not set (S1203: N), the control unit 200 determines that the paper P is thick paper 2 (basis weight 251 to 350 [gsm]). In this case, the control unit 200 sets the upper limit speed X of the image forming speed to upper limit speed 3 (FIG. 16), and sets the lower limit speed Y to lower limit speed 3 (FIG. 16) (S1205).

[0068] Here, the reason why the upper and lower limit image formation speeds are set for each paper basis weight as shown in FIG. 16 is to allow the image forming apparatus to form images within an appropriate image formation speed range. For example, if image formation is performed at an image formation speed that exceeds the upper limit speed 1 for plain paper, the photosensitive drum may not be uniformly charged, which may result in a deterioration in image quality. Also, if image formation is performed at an image formation speed that is below the lower limit speed 1, more heat than necessary may be applied to the paper P when it passes through the fixing device 12, which may result in a deterioration in image quality. For this reason, the table shown in FIG. 16, which includes the maximum image formation speed (upper limit speed) at which image quality can be guaranteed for each paper basis weight and the minimum image formation speed (lower limit speed) at which image quality can be guaranteed for each paper basis weight, is stored in advance in RAM 203.

[0069] In this embodiment, the upper limit speed is set to a speed that does not exceed the image formation speed in the productivity priority mode, because the image formation speed in the "productivity priority mode" is usually the maximum speed at which the image forming apparatus can form images while guaranteeing image quality.

[0070] The control unit 200 acquires the image formation speed determined in the process of S922 in FIG. 14 (S1206). The control unit 200 determines whether this image formation speed exceeds the upper limit speed X set in any of the processes of S1202, S1204, and S1205 (S1207). If the image formation speed exceeds the upper limit speed X (S1207: Y), the control unit 200 changes the image formation speed to the upper limit speed X (S1208). The control unit 200 changes the image formation speed and ends the image formation speed limiting process.

[0071] If the image formation speed does not exceed the upper limit speed X (S1207: N), the control unit 200 determines whether the image formation speed is below the lower limit speed Y set in any one of the processes of S1202, S1204, and S1205 (S1209). If the image formation speed is below the lower limit speed Y (S1209: Y), the control unit 200 changes the image formation speed to the lower limit speed Y (S1210). The control unit 200 changes the image formation speed and ends the image formation speed limiting process. If the image formation speed is not below the lower limit speed Y (S1209: N), the control unit 200 ends the image formation speed limiting process without changing the image formation speed.

[0072] For example, if the basis weight of the paper P is set to 180 [gsm] on the screen in FIG. 11, the default image formation speed in image quality priority mode is determined to be 200 [mm / s] as shown in FIG. 5. If the image formation speed is set to "-1" or "-2" on the screen in FIG. 12, the image formation speed is changed to 200 [mm / s] or less. However, the image formation speed limiting process changes the changed image formation speed back to 200 [mm / s]. This allows the image forming apparatus to form an image on the paper P at an image formation speed that ensures image quality.

[0073] Fig. 17 is a view showing an example of a setting screen for setting the upper and lower limit values ​​of the changeable range of the image formation speed. This screen is displayed on the display 301. The upper limit value 1802 and the lower limit value 1801 change depending on the basis weight of the paper. Fig. 18 is a flowchart showing the process for determining the upper limit value 1802 and the lower limit value 1801. This process is started when the user selects "Image formation speed when image quality is prioritized" from the paper setting change screen in Fig. 10 and presses the OK button.

[0074] The control unit 200 determines whether the image quality priority mode is set by referring to the operation mode stored in the RAM 203 (S1301). If the operation mode is the image quality priority mode (S1301: Y), the control unit 200 acquires the paper type selected on the selection screen in Fig. 8 (S1302). The control unit 200 determines the paper classification using the table shown in Fig. 5 according to the basis weight of the acquired paper type (S1303).

[0075] After determining the paper type, the control unit 200 determines the upper limit value 1802, and then determines the lower limit value 1801. The order in which the upper limit value 1802 and the lower limit value 1801 are determined may be reversed. Here, an example will be described in which the paper basis weight is set to 180 [gsm] on the basis weight setting screen in Fig. 11.

[0076] Based on the determined paper type, the control unit 200 selects the image formation speed in the image quality priority mode from the table shown in Fig. 5. The control unit 200 sets the selected image formation speed as the speed in the image quality priority mode to the variable Z stored in the RAM 203 (S1304). When the paper weight is 180 [gsm], the paper type is "thick paper 1" and the image formation speed (=variable Z) in the image quality priority mode is 200 [mm / s]. After setting the variable Z, the control unit 200 clears the upper limit setting value stored in the RAM 203 to "0" (S1305).

[0077] The control unit 200 selects the image formation speed in the productivity priority mode from the table shown in Fig. 5 based on the determined paper classification. The control unit 200 compares the selected image formation speed in the productivity priority mode with the image formation speed set in variable Z (S1306). When the basis weight is 180 [gsm], the image formation speed in the productivity priority mode is 400 [mm / s]. The image formation speed set in variable Z is 200 [mm / s].

[0078] If the image formation speed in the productivity priority mode is faster than the image formation speed set in variable Z (S1306: Y), control unit 200 increments the upper limit setting value by 1 (S1307). Control unit 200 changes the image formation speed set in variable Z to a speed that is one step faster, depending on the speed that can be set in the image forming apparatus shown in Fig. 4 (S1308). In the case of a basis weight of 180 [gsm], the image formation speed of variable Z is changed from 200 [mm / s] to 300 [mm / s], which is one step faster.

[0079] The control unit 200 repeats the processes of S1306 to S1308 while the image formation speed in the productivity priority mode is faster than the image formation speed set in the variable Z. If the image formation speed in the productivity priority mode becomes equal to or lower than the image formation speed set in the variable Z (S1306: N), the control unit 200 determines the upper limit setting value updated by repeating the processes of S1306 to S1308 as the upper limit value 1802 (S1310).

[0080] When the basis weight is 180 [gsm], the speed in productivity priority mode is 400 [mm / s] and the image formation speed set in variable Z is 200 [mm / s]. By incrementing the upper limit setting value by 1 and changing the image formation speed of variable Z to one step faster, the image formation speed set in variable Z is changed to 300 [mm / s]. By repeating the processes of S1306 to S1308 again, the image formation speed in productivity priority mode becomes the same as the image formation speed set in variable Z, 400 [mm / s]. The upper limit setting value is "+2". At this time, the process proceeds to S1310, and the upper limit setting value "+2" is set in upper limit value 1802.

[0081] After determining the upper limit value 1802, the control unit 200 sets the image formation speed in the image quality priority mode to the variable Z, similar to the process of S1304 (S1311). After setting the variable Z, the control unit 200 clears the lower limit setting value stored in the RAM 203 to "0" (S1311). The control unit 200 selects the minimum image formation speed (200 [mm / s]) from the speeds that can be set in the image forming apparatus shown in FIG. 4. The control unit 200 compares the selected minimum image formation speed with the image formation speed set in the variable Z (S1313).

[0082] If the minimum image formation speed is equal to or greater than the image formation speed set in variable Z (S1313: Y), the control unit 200 determines the lower limit setting value to be lower limit value 1801 (S1321). When the basis weight is 180 [gsm], the minimum speed is 200 [mm / s], and the image formation speed of variable Z is 200 [mm / s]. Therefore, the lower limit value 1801 is determined to be the lower limit setting value "0".

[0083] If the minimum image formation speed is slower than the image formation speed set in variable Z (S1313: N), control unit 200 decrements the lower limit setting value by 1 (S1314). Control unit 200 changes the image formation speed set in variable Z to a speed one step slower, in accordance with the speeds that can be set in the image forming apparatus shown in FIG. 4 (S1315). Control unit 200 repeats the processes of S1313 to S1315 while the minimum image formation speed is slower than the image formation speed set in variable Z.

[0084] If the minimum image formation speed is equal to or greater than the image formation speed set in variable Z (S1313: N), control unit 200 repeats the processes of S1313 to S1315 to determine the updated lower limit setting value as lower limit value 1801 (S1321). When the basis weight is 180 [gsm], the minimum speed is 200 [mm / s] and the image formation speed set in variable Z is 200 [mm / s]. Therefore, in this case, the processes of S1313 to S1315 are not performed.

[0085] After determining the upper limit value 1802 and the lower limit value 1801, the control unit 200 displays the determined upper limit value 1802 and lower limit value 1801 on the display 301 (S1322). In the case of a basis weight of 180 [gsm], as shown in FIG. 17, "+2" is displayed as the upper limit value 1802 and "0" is displayed as the lower limit value 1801.

[0086] If the operating mode is the productivity priority mode (S1301: N), the control unit 200 determines both the upper limit value 1802 and the lower limit value 1801 to be "0" (S1331, S1332). The determined upper limit value 1802 and lower limit value 1801 are displayed on the display 301 (S1322). Note that although the upper limit value 1802 and the lower limit value 1801 in the productivity priority mode are displayed as "0", any display method may be used as long as it indicates that pressing the "+" button and "-" button in FIG. 18 is not valid in the productivity priority mode.

[0087] By setting the upper limit value 1802 and the lower limit value 1801 as described above, when the user changes the image forming speed, it is possible to prevent the image forming speed from being set at a value that does not guarantee image quality.

[0088] (Third embodiment) The image forming apparatus and control unit of the third embodiment have the same configuration as the image forming apparatus and control unit 200 of the first embodiment, so a description thereof will be omitted. Below, differences from the image forming apparatuses of the first and second embodiments will be described.

[0089] In the first embodiment, regardless of whether the operating mode is set to image quality priority mode or productivity priority mode, the "image formation speed when image quality priority is set" is displayed as a changeable item on the paper setting change screen in FIG. 10. However, in productivity priority mode, the "image formation speed setting when image quality priority is set" is not used during image formation. Therefore, in productivity priority mode, even if the user sets the image formation speed for image quality priority mode, the result may differ from the user's expectations. This reduces usability.

[0090] In the third embodiment, in the productivity priority mode, the changeable items on the paper setting change screen do not include "image formation speed when image quality is prioritized." Fig. 19 is a flowchart showing the display setting process on the paper setting change screen.

[0091] The control unit 200 determines whether the productivity priority mode has been selected by the user mode key 308 from the operation mode selection screen of Fig. 6 (S650). If the productivity priority mode has been selected (S650: Y), the control unit 200 sets the state of the image formation speed setting invalid flag for the image quality priority mode, which is stored in the RAM 203, to ON (S651). If the image quality priority mode has been selected (S650: N), the control unit 200 sets the state of the image formation speed setting invalid flag for the image quality priority mode to OFF (S652). The state of the image formation speed setting invalid flag for the image quality priority mode is stored in the RAM 203.

[0092] FIG. 20 is a flowchart showing the process of displaying the paper setting change screen.

[0093] 9 via the operation unit 300 and waits until an instruction to display a screen for changing the paper settings is given (S700: N). When an instruction to display the screen for changing the paper settings is given (S700: Y), the control unit 200 checks the state of the setting invalid flag for the image formation speed in the image quality priority mode stored in the RAM 203 (S701).

[0094] If the setting invalid flag is on (S701: Y), the control unit 200 displays a paper setting change screen A on the display 301 (S702). FIG. 21 is a view showing an example of the paper setting change screen A. The paper setting change screen A is a screen obtained by removing the item "Image formation speed when image quality is prioritized" from the paper setting change screen of FIG. 10. If the setting invalid flag is off (S701: N), the control unit 200 displays a paper setting change screen B on the display 301 (S703). The paper setting change screen B is the paper setting change screen of FIG. 10.

[0095] By the above process, when in productivity priority mode, the item "Image formation speed when image quality is prioritized" is not displayed on the paper setting change screen, and it is not possible to input a setting value to change the image formation speed. This prevents a decrease in usability.

Claims

1. An image forming apparatus that forms an image on a sheet based on an operation mode selected from a plurality of operation modes, an image forming means including a photosensitive member that is driven to rotate, a charging unit that charges the photosensitive member, an exposure unit that exposes the photosensitive member to light in order to form an electrostatic latent image on the photosensitive member that has been charged by the charging unit, a developing unit that develops the electrostatic latent image, an intermediate transfer member onto which the image developed by the developing unit is transferred, and a transfer unit that presses the intermediate transfer member to form a transfer nip and transfers the image on the intermediate transfer member to the paper that passes through the transfer nip; a control means for controlling the rotation speed of the photosensitive member, the rotation speed of the intermediate transfer member, and the transport speed of the paper passing through the transfer nip portion based on the image forming speed; the operation modes include an image quality priority mode in which priority is given to the image quality of the image formed by the image forming device, and a productivity priority mode in which the image formation speed is faster than the image formation speed in the image quality priority mode, a display means for displaying a screen for changing the image forming speed for the image quality priority mode from the image forming speed corresponding to the type of paper, for each paper on which the image is formed, The control means when the image forming apparatus forms an image based on the productivity priority mode, determining the image formation speed from first data for the productivity priority mode and the type of paper, and controlling the rotation speed of the photosensitive member based on the determined image formation speed; When the image forming apparatus forms an image based on the image quality priority mode, if the paper on which the image is to be formed is a paper on which the image formation speed has not been changed, the image formation speed is determined from second data for the image quality priority mode and the type of the paper, and the rotation speed of the photosensitive member is controlled based on the determined image formation speed; When the image forming device forms an image based on the image quality priority mode, if the paper on which the image is to be formed is a paper for which the image formation speed has been changed, the image forming device controls the rotation speed of the photosensitive member based on the changed image formation speed.

2. An image forming device as described in claim 1, characterized in that the image formation speed of the first type of paper determined based on the first data is faster than the image formation speed of the first type of paper determined based on the second data.

3. An image forming apparatus as described in Claim 2, characterized in that there is a second type of paper for which the image formation speed determined based on the first data is the same as the image formation speed determined based on the second data.

4. 4. The image forming apparatus according to claim 3, wherein the second type of paper has a basis weight smaller than that of the first type of paper.

5. The image formation speed for the first type of paper determined based on the second data is different from the image formation speed for the second type of paper determined based on the second data, 2. The image forming apparatus according to claim 1, wherein the first type of paper and the second type of paper have different basis weights.

6. An image forming device as described in Claim 1, characterized in that the upper limit of the speed that can be changed as the image formation speed for paper in the image quality priority mode is the image formation speed corresponding to the type of paper in the first data.

7. 2. The image forming apparatus according to claim 1, wherein the type of the paper is determined based on the basis weight of the paper.

8. 2. The image forming apparatus according to claim 1, wherein the type of the paper is determined based on surface characteristics of the paper.

Images