JP2016109842A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To switch a printing mode to a mode of reducing transfer deviation or a mode of improving registration according to the type of an image.SOLUTION: An image forming apparatus includes: an image forming part that forms an image on a sheet; an operation part; operation keys 53a and 53b with which an image provided on the operation part can be selected; and switching control means for switching to a first priority (priority on color shift) mode or a second priority (priority on transfer deviation) mode in terms of quality of an image formed by the image forming part according to the type of the image selected through the selection operation with the operation keys 53a and 53b.SELECTED DRAWING: Figure 3A

Description

  The present invention relates to an image forming apparatus having a copy function, a scanner function, and the like.

  Conventionally, when printing on thick paper or the like, when the paper enters the fixing roller by controlling the motor speed of the registration roller (PS roller) or the pressure roller of the fixing device in order to prevent transfer deviation at the time of entering the fixing. Has been disclosed (see, for example, Patent Document 1).

  Patent Document 1 discloses an image having a configuration in which images of a plurality of colors are formed using a plurality of latent image carriers, the formed images are sequentially transferred to an intermediate transfer member, and then collectively transferred to a recording medium. In the forming apparatus, the fixing of the recording medium at the time of fixing the image transferred to the recording medium according to the result determined by the means for performing color determination of the original by scanning each original to be imaged An image forming apparatus configured to switch speed is disclosed.

  That is, it is disclosed that the fixing approach speed is switched according to the type of paper (thick paper, OHP, plain paper, etc.) and the color / monochrome mode.

JP 2004-54124 A

  However, for example, when the motor speed is varied in the control for thick paper, the transfer deviation is improved, but there is a problem that the resist deteriorates instead. In other words, the variable control of the motor speed is in a trade-off relationship between the improvement of transfer misalignment and the deterioration of the resist. Therefore, the variable control of the motor speed that satisfies both is extremely difficult, and it is not possible to set the optimum speed. It was extremely difficult. In Patent Document 1, no consideration is given to dealing with both improvement in transfer deviation and improvement in resist.

  The present invention was devised to solve such problems, and its purpose is to switch the printing mode to either a mode for improving transfer deviation or a mode for improving resist depending on the type of image. Another object of the present invention is to provide an image forming apparatus capable of expressing an image requested by a user as much as possible.

  In order to solve the above problems, an image forming apparatus according to the present invention includes an image forming unit that forms an image on a sheet, an operation unit, an operation key that can select an image type provided in the operation unit, and the operation Switching control means for switching to either the first priority mode or the second priority mode, which is the quality of the image formed by the image forming unit, according to the type of the selected image by the key selection operation; It is characterized by having.

  According to the image forming apparatus of the present invention, the first priority mode is a color shift priority mode, and the second priority mode is a transfer shift priority mode.

  According to the image forming apparatus of the present invention, the switching control unit may switch to the second priority mode when a photographic paper is selected as a paper on which an image is printed by the operation key. That is, when photographic paper is selected, printing of characters and the like cannot be considered, and in this case, the mode is switched to the second priority mode in which transfer deviation priority is given.

  According to the image forming apparatus of the present invention, the switching control unit switches to the first priority mode when the character mode is selected by the operation key, and the mode including the photograph is selected by the operation key. In such a case, the second priority mode is switched.

  The image forming apparatus of the present invention includes an image forming unit that forms an image on a sheet, an image input unit that inputs an image from an image reading device or an external device, a determination unit that determines the type of the input image, Switching control means for switching to either the first priority mode or the second priority mode, which is the quality of the image formed by the image forming unit, based on the determination result of the determination means. Yes.

  According to the image forming apparatus of the present invention, the switching control unit switches to the first priority mode (color shift priority mode) when the image type is a character, and when the image type includes a photograph. The configuration is switched to the second priority mode (transfer deviation priority mode). That is, priority is given to improving color misregistration in the case of characters and the like, and priority is given to improving transfer misregistration in the case of photographs and the like.

  According to the image forming apparatus of the present invention, when the switching control unit switches to the second priority mode (transfer deviation priority mode), the conveyance of the paper is started in accordance with the transfer timing by the transfer member. When the sheet passes through the resist member and the transfer member, the peripheral speed of the resist member is made faster than the peripheral speed of the transfer member.

  According to this configuration, since the paper between the registration member and the transfer nip of the transfer member bends, even if the leading edge of the paper that has passed through the transfer nip and reached the fixing member hits the fixing member, this bend. Acts to push out the paper, that is, to push the leading edge of the paper into the fixing nip.

  According to the image forming apparatus of the present invention, when the switching control unit switches to the second priority mode (transfer deviation priority mode), the paper passing through the transfer member enters the fixing member. Before, the peripheral speed of the fixing member is made faster than the peripheral speed of the transfer member.

  According to this configuration, even when the leading edge of the paper that has reached the fixing member hits the fixing member, the leading edge of the paper is drawn by the fixing member that rotates at a higher peripheral speed than the transfer member.

  According to the image forming apparatus of the present invention, when the switching control unit switches to the first priority mode (color shift priority mode), the image forming unit forms the image before forming an image on the paper. Alternatively, registration correction for correcting the position of the image to be performed may be performed. Note that the registration correction here includes skew correction of paper and the like.

  In an actual apparatus, there is a case where the speed is deliberately changed in order to convey a sheet at a constant speed. Accordingly, registration correction is executed when the print mode is switched from an arbitrary mode to the first priority mode which gives priority to color misregistration.

  According to the present invention, the image desired by the user can be expressed to the maximum by switching the print mode depending on the type of image. That is, according to the type of image, both improvement in transfer deviation and improvement in resist can be realized.

1 is a schematic side view of an image forming apparatus according to Embodiment 1 of the present invention. 3 is a block diagram illustrating a configuration of a control system of the image forming apparatus according to Embodiment 1. FIG. It is explanatory drawing which shows an example of the operation screen of a display / operation part. It is explanatory drawing which shows an example of the operation screen of a display / operation part. It is explanatory drawing which shows another example of the operation screen of a display / operation part. It is explanatory drawing which shows another example of the operation screen of a display / operation part. It is explanatory drawing which shows another example of the operation screen of a display / operation part. It is explanatory drawing which shows the example of the control table memorize | stored in the memory | storage part. It is a timing chart which shows rotation speed control of PS roller. 6 is a timing chart illustrating rotation speed control of a pressure roller of a fixing device. 4 is a flowchart for explaining an operation when printing is performed using the image forming apparatus according to the first embodiment. 5 is a block diagram illustrating a configuration of a control system of an image forming apparatus according to Embodiment 2. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1>
FIG. 1 is a schematic side view of an image forming apparatus according to Embodiment 1 of the present invention.

  The image forming apparatus 1 has a copying function for reading an original and forming an image on a sheet. The image reading apparatus 2, an original conveying apparatus (ADF) 3 provided on the upper side of the image reading apparatus 2, and the image reading apparatus 2. The image forming unit 4, the paper feed cassette 5, the manual feed tray 6, and the paper discharge tray 7 are provided on the lower side.

  The document conveying device 3 is supported by a hinge (a fulcrum, not shown) on the back side so as to be openable and closable with respect to the image reading device 2, and is opened and closed by raising and lowering the front end. When the document conveying device 3 is opened, the upper part of the image reading device 2 is opened so that the document can be placed manually. The document conveying device 3 automatically conveys the placed document onto the image reading device 2.

  The image reading apparatus 2 is supported by the hinge (fulcrum) 42 on the back side so as to be openable and closable, and is opened and closed by moving the front end portion up and down. The image reading device 2 reads the placed document or the document conveyed from the document conveying device 3 to generate image data.

  In the image forming apparatus 1, image data corresponding to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y) or a monochrome image using a single color (for example, black). Are treated. The image forming unit 4 is provided with four developing devices 12, photoconductors 13, drum cleaning devices 14, and chargers 15 for forming four types of toner images, each of which includes black, cyan, magenta, and Corresponding to yellow, four image stations Pa, Pb, Pc, and Pd are configured.

  The drum cleaning device 14 removes and collects residual toner on the surface of the photoreceptor 13. The charger 15 uniformly charges the surface of the photoconductor 13 to a predetermined potential. The optical scanning device 11 exposes the surface of the photoreceptor 13 to form an electrostatic latent image. The developing device 12 develops the electrostatic latent image on the surface of the photoconductor 13 to form a toner image on the surface of the photoconductor 13. By the series of operations described above, toner images of each color are formed on the surface of each photoconductor 13.

  An intermediate transfer belt 21 is disposed on the upper side of the photoreceptor 13. The intermediate transfer belt 21 circulates in the direction of arrow C, the residual toner is removed and collected by the belt cleaning device 25, and the toner images of each color formed on the surface of each photoreceptor 13 are sequentially transferred and superimposed. A color toner image is formed on the surface of the intermediate transfer belt 21.

  A nip area is formed between the transfer roller 26a of the secondary transfer device 26 and the intermediate transfer belt 21, and the sheet conveyed through the sheet conveyance path R1 is sandwiched and conveyed in the nip area. When the sheet passes through the nip area, the toner image on the surface of the intermediate transfer belt 21 is transferred and conveyed to the fixing device 17.

  The fixing device 17 includes a fixing roller 31 and a pressure roller 32 that rotate with a sheet interposed therebetween. The fixing device 17 sandwiches the paper on which the toner image is transferred between the fixing roller 31 and the pressure roller 32 and heats and presses the paper to fix the toner image on the paper.

  The paper feed cassette 5 is a tray for storing paper used for image formation, and is provided below the optical scanning device 11. The manual feed tray 6 is a tray for manually placing paper used for image formation, and is provided on one side of the apparatus main body so as to be freely opened and closed.

  The paper is pulled out from the paper feed cassette 5 by the pickup roller 33 or pulled out from the manual feed tray 6 by the pickup roller 37 and is transported through the paper transport path R1 via the secondary transfer device 26 and the fixing device 17. It is carried out to the paper discharge tray 7 via the paper discharge roller 36. In the paper transport path R1, after the paper is temporarily stopped and the leading edges of the paper are aligned, the paper is fed in accordance with the transfer timing of the color toner image in the nip area between the intermediate transfer belt 21 and the transfer roller 26a. A registration roller (registration member) 34 that starts conveyance, a conveyance roller 35 that prompts conveyance of the paper, and a paper discharge roller 36 are arranged.

  Further, when image formation is performed not only on the front side of the paper but also on the back side, the paper is conveyed in the reverse direction from the paper discharge roller 36 to the reverse path Rr, so that the front and back sides of the paper are reversed, and the paper is transferred to the registration roller 34. Then, the image is formed on the rear surface in the same manner as the front surface, and the paper is carried out to the paper discharge tray 7.

  FIG. 2 is a block diagram illustrating a configuration of a control system of the image forming apparatus 1 according to the first embodiment.

  The image forming apparatus 1 includes a control unit 50, a communication I / F unit 51, a storage unit 52, a display / operation unit 53, an image processing unit 54, and the like, which are connected via a bus 56.

  The control unit 50 is configured to be able to communicate with an external device (not shown) via the communication I / F unit 51. The communication I / F unit 51 includes, for example, a FAX communication unit, an Internet communication unit, an infrared communication unit, and the like.

  The control unit 50 includes, for example, one or a plurality of CPUs (Central Processing Units) 50a, a ROM 50b, a RAM 50c, an exposure control unit 50d, a transfer control unit 50e, a fixing control unit 50f, a conveyance control unit 50g, and the like. Various stored programs and data are loaded into the RAM 50c, and the loaded program in the RAM 50c is executed. Thus, the overall operation of the image forming apparatus 1 is controlled based on the contents of instructions from the user while processing the data.

  When the toner image is formed on the surface of the intermediate transfer belt 21, the transfer control unit 50e controls the rotation of the transfer roller 26a of the secondary transfer device 26 and the intermediate transfer belt 21 so that the toner image is formed on the sheet passing through the nip area. Transcript.

  The fixing control unit 50f performs rotation control of the fixing roller 31 and the pressure roller 32 in addition to heating control for fixing, and performs fixing control of the sheet passing through the nip region.

  The conveyance control unit 50g controls the rotation of each roller arranged in the conveyance system from the paper feed cassette 5 to the paper discharge tray 7 to control the conveyance of the sheet at a predetermined sheet conveyance speed.

  The display / operation unit 53 includes, for example, an operation panel including a liquid crystal display and a transparent resistive film type touch panel, and operation keys including hard keys using contact contacts.

  The image processing unit 54 performs various processes on document data optically read by the image reading device 2 to generate image data for image formation. The generated image data is output to the optical scanning device 11 via the exposure control unit 50d of the control unit 50.

  The storage unit 52 stores the read document data and the like, generated image data, and character data and image data received via the communication I / F unit 51.

  3A and 3B are explanatory diagrams illustrating an example of an operation screen of the display / operation unit 53. FIG. However, FIG. 3A is an example of an operation screen that is first displayed when copy is selected in each mode such as copy, scanner, printer, and fax.

  In this operation screen, in addition to conventional operation keys such as color mode, copy density, document, paper, special function, duplex copying, finishing, filing, automatic primary storage, the quality of the image formed by the image forming unit 4 The first priority mode “color misalignment priority mode” operation key 53a and the second priority mode “transfer misalignment priority mode” operation key 53b are newly provided.

  Here, the “color misregistration priority mode” is a mode for improving so-called registration, and is a mode for controlling the motor speed control so that the paper transport speed becomes constant. In other words, control for increasing or decreasing the sheet conveyance speed in the sheet conveyance process is performed, and the sheet is conveyed at a constant speed from the sheet feeding cassette 5 to the sheet discharge tray 7, and in particular, the sheet from the start of transfer to the end of fixing. The conveyance speed is controlled to a constant speed. Note that the paper transport speed here refers to the paper process speed (image forming speed).

  The “transfer deviation priority mode” is a mode in which the motor speed control, that is, the paper conveyance speed, is controlled so as to reduce the impact generated when the leading edge of the paper enters the fixing state. This is a mode for controlling increase / decrease of the sheet conveyance speed up to. This transfer deviation priority mode will be described later.

  That is, the user himself / herself operates one of the operation keys 53a and 53b, so that the print mode of the data to be printed can be selected from the color misalignment priority mode and the transfer misalignment priority mode. Yes.

  In the first embodiment, when the copy density operation key 53c is selected from the operation screen shown in FIG. 3A, the operation screen shown in FIG. 3B is displayed. In this operation screen, in addition to manual copy density, it is possible to select the type of document, and as the type of document, “character”, “character / print photo”, “character / print paper photo”, “ One of “printed photograph”, “photographic paper photograph”, and “map” can be selected. Therefore, the user can select one of the document types from the operation screen and press the “OK” button on the upper right of the screen to select the document type and copy density.

  Here, in the first embodiment, one of the color misregistration priority mode and the transfer misalignment priority mode is set in accordance with the type of document. In other words, it is possible to automatically select either the color misregistration priority mode or the transfer misregistration priority mode as the print mode without selecting the mode directly by the user by simply selecting the type of document. ing.

  For this reason, each key for selecting the type of document is associated with either the color misregistration priority mode or the transfer misalignment priority mode, and a control table indicating the correspondence is stored in the storage unit 52.

  FIG. 5 is a control table showing the correspondence between the document type and the print mode stored in the storage unit 52.

  In this example, when the type of document is “character” and “map”, the color misregistration priority mode is associated, and in the case of “character / print photo”, “print photo”, “print paper photo” Is associated with a transfer deviation priority mode. That is, when an image other than a character or a line diagram (for example, a solid diagram or a photograph) is included, the transfer deviation priority mode is associated with the selected image.

  4A to 4C are explanatory diagrams illustrating other examples of the operation screen of the display / operation unit 53, which are operation screen examples when setting paper to be printed.

  That is, when the paper key 53d on the operation screen shown in FIG. 4A is selected, the process proceeds to FIG. 4B, and the “plain paper” operation key 53e is selected from the operation screen shown in FIG. 4B. That is, the selection of the “plain paper” operation key 53e on this operation screen is the selection of the manual feed tray 6, and when the manual feed tray 6 is selected, the operation screen shown in FIG. 4C is displayed. In this operation screen, one of the 12 types of paper can be selected.

  Here, when the “printing paper” operation key 53f is selected from the operation screen, it is difficult to normally print only data of characters and lines on the printing paper. Therefore, in the first embodiment, when “photographic paper” is selected, the transfer deviation priority mode is selected. Here, “photographic paper” refers to paper for printing photographic images, and has a broad meaning including glossy paper having gloss on the surface as well as photographic paper coated with a photosensitive material on the surface. It is so-called photographic paper.

  That is, in the first embodiment, each of the operation keys corresponds to the switching control means described in the claims.

  Next, an example of sheet conveyance speed control when the transfer deviation priority mode is selected by the above operations will be described with reference to timing charts shown in FIGS. However, FIG. 6 shows an example of controlling the peripheral speed when the PS roller 34 rotates as the paper conveyance speed control, and FIG. 7 shows the pressure roller 32 constituting the fixing device 17 as the paper conveyance speed control. It is an example which controls the peripheral speed at the time of rotation.

  The peripheral speed control shown in FIG. 6 is such that the leading edge of the paper is fixed to the fixing device 17 by increasing the peripheral speed of the rotating PS roller 34 until the transfer rush or the fixing rush in the thick paper mode printing. In this control, the collision with the fixing roller 31 or the pressure roller 32 is alleviated to reduce transfer deviation and exposure deviation.

  Further, the peripheral speed control shown in FIG. 7 is performed by increasing the peripheral speed of the pressure roller 32 that constitutes the fixing device 17 during the cardboard mode printing until the time of transfer entry or fixing entry. This is control that suppresses fluctuation and reduces transfer deviation and exposure deviation.

(1) Description of circumferential speed control of PS roller 34 First, circumferential speed control of the PS roller 34 shown in FIG. 6 will be described.

  When the leading edge of the paper transported through the paper transport path R1 reaches the PS roller 34, the transport control unit 50g temporarily stops the paper transport and aligns the leading edges of the paper. Thereafter, the conveyance control unit 50g adjusts the timing of the PS roller 34 at time t11 in accordance with the transfer timing of the color toner image in the nip area (hereinafter referred to as transfer nip) between the intermediate transfer belt 21 and the transfer roller 26a. Rotation is started and paper transport is started at normal process speed. After the leading edge of the sheet passes through the transfer nip, the PS roller at time t12 before reaching the nip area (hereinafter referred to as the fixing nip) between the fixing roller 31 and the pressure roller 32 of the fixing device 17. The peripheral speed of 34 is increased from the normal process speed so far. After that, at time t13 when some time T1 has elapsed, the speed increase is finished, and the normal process speed is restored (decelerated) again. When the paper completely passes the PS roller 34, the rotation of the PS roller 34 is stopped at time t14.

  Here, the speed increase rate is set in advance according to the type of paper to be conveyed. For example, the types of cardboard are classified into four types from a relatively thin level 1 to a thickest level 4 as a cardboard, and the process speed for cardboard of level 1, 2 is P1, and the process for cardboard of level 3, 4 Assuming that the speed is set to P2, the speed increase rate with respect to the process speed P1 is set to, for example, + 1% for level 1 and 2 thick paper, and the speed increase rate with respect to the process speed P2 is set to, for example, level 3 and 4 Set to + 3%. The speed increase rate may be set in advance in consideration of transfer deviation, registration, printing magnification, and the like. If the cardboard level is not selected, for example, + 2% may be set as a default value as the speed increase rate.

  As described above, the peripheral speed of the PS roller 34 is increased from the normal process speed by the time T1 between the time t12 and the time t13 (specifically, the sheet passes through the PS roller 34 and the transfer roller 26a). In this case, the peripheral speed of the PS roller 34 is made faster than the peripheral speed of the transfer roller 26a), so that the sheet between the PS roller 34 and the transfer nip is conveyed in a bent state. This state continues until the trailing edge of the sheet passes through the PS roller 34. Further, the amount of bending of the paper can be adjusted by adjusting the increasing time T1.

  Accordingly, since the sheet between the PS roller 34 and the transfer nip is bent, the leading edge of the sheet that has passed through the transfer nip and reached the fixing nip is detached from the fixing nip and the surface of the fixing roller 31 or the pressure roller 32. Even if it hits, the bending force acts to push out the paper. That is, it acts to push the leading edge of the paper into the fixing nip. As a result, the impact at the leading edge of the paper when drawn into the fixing nip is reduced. Therefore, slight blur (movement that strikes for a moment) transmitted to the entire sheet due to the collision of the leading edge of the sheet is alleviated, and transfer deviation and exposure deviation at the transfer portion affected by the blur can be improved.

  Further, when the sheet between the PS roller 34 and the transfer nip is bent, the pushing direction of the leading end of the sheet pushed out from the transfer nip is changed. That is, it is possible to adjust the pushing direction of the leading edge of the paper to some extent by adjusting the amount of bending of the paper. Therefore, by adjusting the amount of deflection of the sheet so that the leading edge of the sheet is directed toward the fixing nip, the leading edge of the sheet can easily enter the fixing nip. In this way, even by adjusting the pushing direction of the leading edge of the paper by utilizing the bending of the paper, it is possible to avoid or reduce the collision of the leading edge of the paper, so that the slight blur transmitted to the entire paper by the collision of the leading edge of the paper ( (Moving momentarily forcing) is mitigated, and transfer deviation and exposure deviation at a transfer portion affected by the shake can be further improved.

(2) Explanation of peripheral speed control of pressure roller 32 Next, the peripheral speed control of the pressure roller 32 shown in FIG. 7 will be described.

  The fixing control unit 50f adjusts the pressure roller 32 at time t21 in accordance with the timing when the leading edge of the first sheet conveyed through the sheet conveyance path R1 passes through the transfer roller 26a and comes to the front of the fixing nip. Start rotating. However, the rotation at this time starts in a state where the peripheral speed of the pressure roller 32 is increased from the normal process speed. Then, at time t22 immediately after the leading edge of the sheet enters the fixing nip, the peripheral speed of the pressure roller 32 is returned (decelerated) to the normal process speed. During the subsequent sheet conveyance, the normal process speed is maintained until the trailing edge of the sheet passes through the fixing nip. Thereafter, the peripheral speed of the pressure roller 32 is increased from the normal process speed at time t23 in accordance with the timing when the leading edge of the next sheet comes before the fixing nip, and immediately after the leading edge of the sheet enters the fixing nip. At time t24, the peripheral speed of the pressure roller 32 is restored (decelerated) to the normal process speed again. Thereafter, this control is repeated.

  However, in the peripheral speed control of the pressure roller 32, the speed increase rate is set to + 10% for each of the process speeds P1 and P2, regardless of the type of cardboard. The speed increase rate may be set in advance in consideration of transfer deviation, registration, printing magnification, and the like.

  As described above, the peripheral speed of the pressure roller 32 is increased from the normal process speed by the time T2 between the time t21 and the time t22 (specifically, the sheet passing through the transfer nip is transferred to the fixing nip. Even if the leading edge of the paper hits the surface of the pressure roller 32 by making the peripheral speed of the pressure roller 32 faster than the peripheral speed of the transfer roller 26a before entering, the peripheral speed of the transfer roller 26a The leading edge of the sheet is drawn into the fixing nip by the pressure roller 32 that rotates at a high peripheral speed. As a result, the impact of the front end of the sheet on the pressure roller 32 is reduced. Therefore, slight blur (movement that strikes for a moment) transmitted to the entire sheet due to the collision of the leading edge of the sheet is alleviated, and transfer deviation and exposure deviation at the transfer portion affected by the blur can be improved.

  In the circumferential speed control of the pressure roller 32, if the timing at which the leading edge of the paper enters the fixing nip can be accurately grasped, the circumferential speed is increased only momentarily immediately before the leading edge of the paper enters the fixing nip. It should be fast. That is, the above time T2 may be instantaneous.

  In the peripheral speed control, the case where the peripheral speed of the pressure roller 32 is increased at the timings of the times t21 and t23 is described. On the contrary, the peripheral speed control is performed at the timings of the times t21 and t23. The peripheral speed of the pressure roller 32 may be reduced (for example, −10%). As a result of experiments on the case where the peripheral speed of the pressure roller 32 is reduced, the present inventors also reduce the impact of the leading edge of the paper on the pressure roller 32 in this case as in the case of the acceleration. , Make sure that the objective is achieved.

  The above is the description of the sheet conveyance speed control when the transfer deviation priority mode is selected.

  Next, a mode selection operation when printing is performed using the image forming apparatus 1 having the above configuration will be described with reference to a flowchart shown in FIG.

  When starting printing, the user selects the type of document to be printed from the operation screen shown in FIG. 3A.

  Here, prior to the selection of the document type, either the “color misalignment priority mode” operation key 53a or the “transfer misalignment priority mode” operation key 53b displayed on the lower right of the screen by the user is displayed. When an operation is performed (steps S1 and S2) and then a start key for printing (not shown) is operated, the control unit 50 executes a print mode according to the operation key.

  That is, when the operation key 53a is operated (when it is determined Yes in step S1), the control unit 50 executes printing in the color misregistration priority mode set corresponding to the operation key ( Step S6). That is, in this case, printing is executed by controlling the motor speed so that the paper transport speed is always constant.

  On the other hand, when the operation key 53b is operated (when determined Yes in step S2), the control unit 50 performs printing in the transfer deviation priority mode set corresponding to the operation key ( Step S7). That is, in this case, the printing is executed by performing the peripheral speed control (1) and (2).

  Here, in the “transfer deviation priority mode”, the peripheral speed control of both (1) and (2) may be performed, or only one of the peripheral speed controls may be performed.

  On the other hand, from the operation screen shown in FIG. 3A, the operation keys 53a and 53b are not operated (No in Step S1 and Step S2), and the copy density operation key 53c is selected (Yes in Step S3). When an arbitrary key is operated from the operation screen shown (Yes in step S4) and then a print start button (not shown) is operated, the control unit 50 follows the operation key selected from the operation screen of FIG. 3B. Execute print mode.

  That is, when “character” or “map” is selected as the document type from the operation screen of FIG. 3B (Yes in step S5), the control unit 50 sets the color misregistration priority mode according to the control table of FIG. Execute (Step S6). On the other hand, when “text / print photo”, “print photo”, or “photographic paper photo” is selected as the document type from the operation screen of FIG. 3B (No in step S5), the control of FIG. The transfer deviation priority mode is executed according to the table (step S7).

  If another key is selected in step S3 and step S4, a process according to the selected key is executed (step S8).

  When the operation key 53a or 53b is operated from the operation screen of FIG. 3A and then any operation key of the operation screen shown in FIG. 3B is operated, the control unit 50 operates the operation key of FIG. 3B. And the print mode may be executed by giving priority to the operation of the operation key 53a or 53b.

  When the user selects paper, the paper key is selected from the operation screen shown in FIG. 4A, “plain paper” is selected from the operation screen shown in FIG. 4B, and “photographic paper” is selected from the operation screen shown in FIG. 4C. In this case, the control unit 50 has already operated one of the operation keys 53a and 53b from the operation screen of FIG. 3A or the operation key of the document type on the operation screen shown in FIG. 3B. The operation of these operation keys is invalidated even when the printer is operated, and the print mode is executed with priority given to the mode associated with the “photographic paper” selected in the paper selection. do it.

  According to the first embodiment, an image can be printed in an optimum print mode corresponding to the type of image by selecting the type of image by the user's own selection operation. That is, according to the type of image, printing can be executed by selecting either improvement of transfer deviation or improvement of resist.

<Embodiment 2>
FIG. 9 is a block diagram showing the configuration of the control system of the image forming apparatus according to Embodiment 2 of the present invention.

  In the image forming apparatus 1 according to the second embodiment, in addition to the configuration of the image forming apparatus according to the first embodiment, data stored in the storage unit 52 (that is, data of a document read from the image reading apparatus 2 or And an image type discriminating unit 55 for discriminating the type of the image based on data such as characters and images received via the communication I / F unit 51. Further, the control unit 50 is configured to execute printing by switching to either the color misregistration priority mode or the transfer misalignment priority mode based on the determination result of the image type determination unit 55. That is, in the second embodiment, the control unit 50 corresponds to the switching control unit described in the claims.

  Here, in the second embodiment, when the data to be printed out of the data stored in the storage unit 52 is data such as characters and ruled lines that does not include photo data, Printing is executed in the color misregistration priority mode, and when at least photo data is included in the data to be printed, printing is executed in the transfer misalignment priority mode. In other words, in the case of characters and the like, priority is given to the improvement of color misregistration, and in the case of photographs and the like, the printing is given priority to the improvement of transfer misalignment and exposure deviation.

  According to the second embodiment, the control unit 50 automatically determines the type of image included in the data to be printed without the user himself / herself selecting, so that the optimum print mode corresponding to the type of image is obtained. You can print an image.

<Embodiment 3>
In the first and second embodiments, the print mode is switched to either the color misalignment priority mode or the transfer misalignment priority mode according to the type of document. In the third embodiment, in addition to such switching control, When the print mode is switched from the previous mode to the color misregistration priority mode, an image formed by the image forming unit 4 before forming an image on the paper (that is, before executing the color misregistration priority mode). In this configuration, a well-known registration correction is performed to correct the position. This registration correction includes skew correction of the paper.

  In an actual apparatus, there is a case where the speed is deliberately changed in order to convey a sheet at a constant speed. In addition, since registration correction is normally performed when the power is turned on, according to the present invention, the registration correction is performed when the print mode is switched from the arbitrary mode to the color misregistration priority mode. Yes. Thereby, the color shift of an image can be improved more reliably.

  It should be noted that the embodiment disclosed herein is illustrative in all respects and does not serve as a basis for limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiment, but is defined based on the description of the scope of claims. Moreover, all the changes within the meaning and range equivalent to a claim are included.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image reader 3 Document feeder (ADF)
DESCRIPTION OF SYMBOLS 4 Image formation part 5 Paper feed cassette 6 Manual feed tray 7 Paper discharge tray 11 Optical scanning device 12 Developing device 13 Photoconductor 14 Drum cleaning device 15 Charger 17 Fixing device 21 Intermediate transfer belt 25 Belt cleaning device 26 Secondary transfer device 26a Transfer roller 31 Fixing roller (fixing member)
32 Pressure roller (fixing member)
33 Pickup roller 34 Registration roller (PS roller, registration member)
36 Paper discharge roller 50 Control unit 50a CPU
50b ROM
50c RAM
50d Exposure control unit 50e Transfer control unit 50f Fixing control unit 50g Transport control unit 51 Communication I / F unit 52 Storage unit 52a Exposure history storage unit 52b Print history storage unit 53 Display / operation unit 53a to 53e Operation key 54 Image processing unit 55 Image type discriminator 56 bus

Claims (10)

An image forming unit for forming an image on paper;
An operation unit;
An operation key capable of selecting an image type provided in the operation unit;
Depending on the type of image selected by the selection operation of the operation key,
An image forming apparatus comprising: a switching control unit configured to switch to a first priority mode or a second priority mode which is a quality of an image formed by the image forming unit. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the first priority mode is a color shift priority mode, and the second priority mode is a transfer shift priority mode. The image forming apparatus according to claim 2,
The switching control unit switches to the first priority mode when a character mode is selected by the operation key, and switches to the second priority mode when a mode including a photograph is selected by the operation key. An image forming apparatus. The image forming apparatus according to claim 3, wherein
The image forming apparatus according to claim 1, wherein the switching control unit switches to the second priority mode when a sheet for printing a photographic image is selected as a sheet for printing an image by the operation key. An image forming unit for forming an image on paper;
Image input means for inputting an image from an image reading device or an external device;
A discriminating means for discriminating the type of input image;
Switching control means for switching to either the first priority mode or the second priority mode, which is the quality of the image formed by the image forming unit, based on the determination result of the determination means. An image forming apparatus. The image forming apparatus according to claim 5, wherein
The image forming apparatus, wherein the first priority mode is a color shift priority mode, and the second priority mode is a transfer shift priority mode. The image forming apparatus according to claim 5, wherein:
The switching control unit switches to the first priority mode when the image type is text, and switches to the second priority mode when the image type includes a photograph. An image forming apparatus according to any one of claims 1 to 7,
When the switching control unit switches to the second priority mode, when the sheet passes through the registration member and the transfer member that starts conveying the sheet in accordance with the transfer timing by the transfer member, An image forming apparatus characterized in that a peripheral speed of a resist member is higher than a peripheral speed of the transfer member. An image forming apparatus according to any one of claims 1 to 7,
When the switching control means switches to the second priority mode, the peripheral speed of the fixing member is made higher than the peripheral speed of the transfer member before the sheet passing through the transfer member enters the fixing member. An image forming apparatus. The image forming apparatus according to any one of claims 1 to 9, wherein
When the switching control unit switches to the first priority mode, registration correction is performed to correct the position of the image formed by the image forming unit before forming an image on a sheet. Image forming apparatus.

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