JP4622614B2 - Image forming apparatus - Google Patents

Description

  The present invention is compatible with four color toners of yellow (Y), magenta (M), cyan (C), and black (K) for forming a monochrome image or a color image on the surface of an image output medium such as recording paper. In addition to the four image forming units described above, for example, a transparent toner that absorbs invisible light as a special color (special color), a light color toner (toner such as light magenta and light cyan) for improving graininess, and a color gamut are expanded. The present invention relates to a multicolor image forming apparatus capable of using one or a plurality of image forming units corresponding to toners such as red and green for the purpose, and gold and silver for special use.

  In general, as a multi-color image forming apparatus (color image forming apparatus) such as a color copying machine, a color printer, or a color facsimile employing an electrophotographic system, a multi-color image forming employing a so-called tandem intermediate transfer system. The device is widely used.

  In this tandem multicolor image forming apparatus, a plurality of photosensitive drums for forming toner images of yellow, magenta, cyan, black, and special colors are disposed along the surface of the endless intermediate transfer belt. In addition, a charging unit, an exposure unit, a developing unit, and the like are provided around each photosensitive drum.

  In this tandem multicolor image forming apparatus, toner images of respective colors formed in yellow, magenta, cyan, black, and special colors on the respective photosensitive drums are sequentially superimposed on the intermediate transfer belt. The toner images of yellow, magenta, cyan, black, and special colors that have been transferred onto the intermediate transfer belt are transferred to the recording paper in a batch. A color image is formed (see, for example, Patent Document 1).

  In addition, an image forming apparatus using such a special color has been proposed in which a so-called transparent toner using a near-infrared absorbing dye is used to superimpose a code such as an invisible code on a visible image ( For example, see Patent Document 2.)

  At the same time, an invisible image having infrared absorptivity is formed on an image output medium such as recording paper, and information is embedded to embed security functions such as anti-counterfeiting and deterrence measures, originality assurance, or coordinate information etc. An image forming apparatus using a special color for improving the added value of an output medium is disclosed (for example, see Patent Document 3).

  In addition, the conventional tandem type image forming apparatus is configured to switch between a mode for forming chromatic images of cyan, magenta, and yellow and a mode for forming a monochrome image (single color mode), and further, monochrome image formation In order to stabilize the transfer operation of the transfer material conveyance belt with respect to the black image forming photoconductor, the transfer material conveyance belt is separated from the chromatic recording photoconductor in the mode (for example, patents). Reference 4).

  Further, the conventional image forming apparatus using the photosensitive drum includes a full-color image forming process by superimposing a plurality of color toner images on a photosensitive drum as an image carrier, and a mono-color image forming process by a single color toner image. In order to enable image formation by arbitrarily selecting one of them, a full-color image developing unit having a toner of each color of yellow, magenta, cyan, and full-color black for forming a full-color image, A monochrome image developing unit having black and white image black toner for forming a monochrome image is separately provided.

  In this conventional image forming apparatus using a photosensitive drum, a black toner image is generated by using only a black and white image developing unit during black and white image formation, and a full color toner image is generated by a full color image developing unit during normal full color image formation. (For example, refer to Patent Document 5).

The conventional image forming apparatus as described above can form a special color image in addition to a black and white image and a full color image. However, since these image forming apparatuses all have special colors set in advance, the special colors can be replaced with a special color, for example, in order to form an invisible image. Users can use a single image forming device for various purposes such as changing to light colors such as infrared absorbing color, light magenta or light cyan to improve image quality or adding security information using transparent toner. It cannot be set so that a monochrome image that is realized or frequently used can be formed with high reliability over a long period of time by free maintenance.
JP 63-071867 JP2002-240387 JP2003-186238 JP 2001-005305 A JP2003-241477

  In view of the above-described points, the present invention allows a user to set various uses according to needs such as changing the special color arbitrarily to improve image quality or adding a security effect with a single image forming apparatus. Alternatively, it is an object of the present invention to newly provide an image forming apparatus that can be set so that a frequently used monochrome image can be formed with high reliability over a long period of time by free maintenance.

The image forming apparatus according to claim 1, wherein the image forming unit for black color, the image forming unit for cyan color, the image forming unit for magenta color, the image forming unit for yellow color, and one or more. comprising an image forming unit for special colors, a full-color image, a formable and the tandem-type image forming apparatus of a toner image on the intermediate transfer unit or the image output medium conveyed to the sheet conveying unit , At least the special color image forming unit can be mounted by replacing with an image forming unit of a different special color type, and depending on the special color type in the mounted special color image forming unit, Only the black color image forming unit is rolled on the image output medium conveyed to the intermediate transfer unit or the paper conveying unit. The toner image is transferred by separating the image forming unit, or only the image forming unit for black color and the image forming unit for one or more special colors are brought into contact with each other to separate the other image forming units. In the image forming apparatus for transferring the toner image , the black color image forming unit and the special color image forming unit disposed adjacent to the black color image forming unit can be replaced with the black color image. It is characterized in that it can be replaced with a large-size image forming unit provided with a large-diameter photosensitive drum formed larger than the diameter of the photosensitive drum provided in the forming unit .

  By configuring as described above, the image quality can be improved by making it possible to change the special color arbitrarily and form a full-color image with the special color added or a monochrome image with the special color added with one image forming apparatus. it can. In particular, when forming a black and white image, the user can set various uses such as adding a security effect by superimposing and forming an invisible image using a transparent toner as a special color according to needs. Therefore, the added value of the image forming apparatus can be improved.

Furthermore, in the case of black (K color) high usage environments frequently used of, if utilized in mounting a large image forming unit, the service life of a large径感light drum definitive in this large image forming unit, other As compared with the photosensitive drums in the cyan (C), magenta (M), and yellow (Y) image forming units, it is possible to obtain long-term reliability.

The invention of claim 2 is the image forming apparatus according to claim 1, an image forming unit for special color, and forming a transparent toner image having an absorption band in the visible light.

With the configuration described above, in addition to the operation and effect of the invention according to claim 1, a full color formed by superimposing an invisible image related to security information by a transparent toner image by an image forming unit for special colors. A black-and-white image formed by superimposing an invisible image related to security information by an image or a transparent toner image can be formed, and a security effect can be added.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect , an LED print head is integrally formed in the image forming unit.

By configuring as described above, in addition to the operation and effect of the invention according to claim 1 or 2 , in this image forming apparatus, an LED print head as an exposure means (latent image forming means) is provided for each image. The configuration is integrated for each forming unit. For this reason, in this image forming apparatus, even when the black image forming unit and the special color image forming unit can be replaced with a large image forming unit and mounted, the exposure means can be arranged in the layout inside the apparatus main body. Since it can be arranged without being restricted, devices installed in the image forming apparatus can be mounted in high density in a small space, and the image forming apparatus can be miniaturized.

The invention according to claim 4, in the image forming apparatus according to any one of claims 1 to 3, the transfer position of the large image forming unit for image output medium is conveyed to the intermediate transfer unit or paper transporting unit Of the image forming unit for black color and the image forming unit for special color exchanged with this, the transfer position corresponding to the downstream side in the moving direction of the image output medium conveyed to the intermediate transfer unit or the paper conveying unit It is characterized by setting.

By configuring as described above, effects of the invention according to any one of claims 1 to 3, in addition to the effect, and prevented from becoming impossible has interference of the adjacent image forming units mounted, The transfer position of the large photosensitive drum in the large image forming unit can be adapted to the engine pitch conditions of the tandem configuration in the other image forming units. Can be maintained.

According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the pitch between the transfer position of the large image forming unit and the transfer position of another adjacent image forming unit is the transfer of another image forming unit. It is characterized by being an integral multiple of the position pitch .

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, when the large-sized image forming unit is mounted, the black image forming unit replaced with the large-sized image forming unit is provided. The two toner cartridges that are adjacent to each other to replenish toner to the special color image forming unit are removed, and a large-capacity cartridge is loaded in the space corresponding to the two toner cartridges. The toner is supplied to the developing device provided in the large image forming unit through a flexible tube.

According to the configuration described above, in addition to the operation and effect of the invention according to any one of claims 1 to 5, in order to supply toner as a consumable from a large capacity cartridge. Therefore, it is possible to improve the maintainability by reducing the replacement frequency of the large-capacity cartridge and to obtain long-term reliability. In the invention of claim 6 , it is assumed that the toner cartridge is mounted in the image forming apparatus. However, in the image forming apparatus of claims 1 to 5 , the toner supply form is toner. Needless to say, the toner cartridge is not limited to a state where the toner cartridge is mounted in the image forming apparatus.

  The image forming apparatus according to the present invention allows a user to set various uses according to needs such as changing the special color arbitrarily to improve the image quality or adding a security effect with a single image forming apparatus. Alternatively, it is possible to make settings so that a frequently used black and white image can be formed with high reliability over a long period of time by free maintenance, and the added value of the image forming apparatus can be improved.

  An image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. The image forming apparatus shown in FIG. 1 is configured as a tandem digital color image forming apparatus.

  Inside the tandem-type digital color image forming apparatus 11 body is black (K), a so-called transparent color (i) using a near-infrared absorbing dye having an absorption range for invisible light as a special color, cyan (C) , Five image forming units 10K, 12i, 14C used for primary transfer of magenta (M) and yellow (Y) toner images to an intermediate transfer belt 32 as an image carrier used for transfer. 16M and 18Y are arranged at predetermined intervals. This image forming apparatus may be configured as a color image forming apparatus having six or more colors, in addition to these five colors, and a special color such as a so-called corporate color, which is a user specific color.

  The image forming unit 12i is configured as a replaceable image forming unit as shown in FIG. 3, for example, and is a light color toner (light magenta, light cyan) for improving full color image quality (Gamut enlargement, graininess improvement). Image forming unit 12X corresponding to toners of red, green, etc. for widening the color gamut, gold toner, silver toner, etc. for special use can be prepared separately and replaceable with this image forming unit 12i. Constitute.

  As shown in FIGS. 1 and 6, the five image forming units 10K, 12i, 14C, 16M, and 18Y are all configured in the same manner. Each of the image forming units 10K, 12i, 14C, 16M, and 18Y includes a photosensitive drum 20 that is rotationally driven at a predetermined speed, and around the photosensitive drum 20 in the rotation direction (the direction of arrow A in the figure). The primary transfer roll 22, the cleaning device 24 that cleans the surface of the photosensitive drum 20, the charging charger 26 that is a charging device that uniformly charges the surface of the photosensitive drum 20, and the surface of the photosensitive drum 20. Are formed on an LED print head 28 (hereinafter referred to as “LPH”) as an image exposure apparatus (exposure means) that exposes an image corresponding to a predetermined color to form an electrostatic latent image, and on the photosensitive drum 20. And a developing device 30 as a developing device for developing the electrostatic latent image with toner of a predetermined color.

  The photosensitive drum 20, the cleaning device 24, the charging charger 26, the LED print head 28, and the developing device 30 disposed around the photosensitive drum 20 are integrated as a unit, and are individually united from the color image forming apparatus 11. It is configured to be replaceable.

  The image forming units 10K, 12i, 14C, 16M, and 18Y are each equipped with a crumb having a RAM (Random Access Memory), not shown. This crumb is configured in the same manner as that mounted on a general image forming unit used in the past, and rewritable information unique to each image forming unit 10K, 12i, 14C, 16M, 18Y is stored. In addition, it is configured to be readable.

  When the image forming units 10K, 12i, 14C, 16M, and 18Y are detachably attached to the digital color image forming apparatus 11, this crumb is applied to a central control device (not shown) installed inside the digital color image forming apparatus 11. In order to exchange information, it is configured to be detachably connected through an outlet or the like.

  In this digital color image forming apparatus 11, image data of each color is sequentially output to each of the image forming units 10K, 12i, 14C, 16M, and 18Y, and emitted from each LED print head 28 according to the image data. Laser light is applied to the surface of the corresponding photosensitive drum 20 to form an electrostatic latent image. The electrostatic latent images formed on the respective photosensitive drums 20 are respectively black (K), transparent color (i) as a special color, cyan (C), and the like by a developing device 30 as a corresponding developing device. The toner images are developed as magenta (M) and yellow (Y) toner images.

  That is, when an image is formed by each of the image forming units 10K, 12i, 14C, 16M, and 18Y configured as described above, the surface of the photosensitive drum 20 is uniformly charged by the charging charger 26, and then Then, an electrostatic latent image corresponding to each color is formed by exposing the charged surface of the photosensitive drum 20 with an image forming laser beam emitted from the LED print head 28 according to image data. The electrostatic latent image formed on the photosensitive drum 20 in this way is black (K), transparent color (i) as a special color, cyan (C), magenta (M), yellow by each developing device 30. The toner image is developed with toner of each color (Y). These toner images are sequentially transferred in multiple layers onto an intermediate transfer belt (image carrier used for secondary transfer) 32 to which the photosensitive drum 20 is brought into contact by the charging action of the primary transfer roll 22.

  The image forming units 10K, 12i, 14C, 16M, and 18Y remove residual toner, paper dust, and the like from the surface of the photosensitive drum 20 after the transfer process of each toner image is completed by the cleaning device 24. Prepare for the next image forming process.

  The cleaning device 24 is configured to remove residual toner, paper dust, and the like on the photosensitive drum 20 by a cleaning blade 34 (shown in FIG. 2). In addition, residual toner, paper dust, and the like are removed from the surface of the intermediate transfer belt 32 after the toner image transfer process is completed by a cleaning device 36 disposed at a position in contact therewith to prepare for the next image forming process. .

  Black (K), transparent color (i) as a special color, cyan (C), magenta formed on the photosensitive drum 20 of each of the image forming units 10K, 12i, 14C, 16M, and 18Y in this way. The toner images of each color of (M) and yellow (Y) are intermediate transfer belts (secondary transfer belts) that are endless belt members arranged over the respective image forming units 10K, 12i, 14C, 16M, and 18Y. Are transferred in multiple by the corresponding primary transfer rolls 22.

  Each primary transfer roll 22 is disposed so as to be in contact with the back side of the intermediate transfer belt 32 at a position corresponding to each photosensitive drum 20 of the corresponding image forming unit 10K, 12i, 14C, 16M, 18Y. .

  Among these primary transfer rolls 22, except for the primary transfer roll 22 corresponding to the black (K) color image forming unit 10 </ b> K, the remaining transparent colors (i), cyan (C), magenta ( Retracting devices 33i, 33C, 33M, and 33Y are mounted on the primary transfer rolls 22 corresponding to the image forming units 12i, 14C, 16M, and 18Y for the respective colors M) and yellow (Y), respectively. 4 for separating the image forming units 10K, 12i, 14C, 16M, and 18Y from the intermediate transfer belt 32 and the transfer operation position shown in FIG. 1 by the corresponding retract devices 33i, 33C, 33M, and 33Y. The retraction position shown in FIG.

  The retracting devices 33i, 33C, 33M, and 33Y can be constituted by, for example, an actuator that contracts a rod that is pivotally attached to the tip of the primary transfer roll 22, or other commonly used operation mechanisms.

  The retraction device 33i attached to the image forming unit 12i for the transparent color (i) as the special color is an image forming unit 14C for each of the other colors cyan (C), magenta (M), and yellow (Y). , 16M, and 18Y, respectively, the retractors 33C, 33M, and 33Y can be driven and controlled independently.

  A transfer bias power source (not shown) is connected to the primary transfer roll 22, and a transfer bias voltage having a polarity opposite to a predetermined toner polarity (positive polarity in the present embodiment) is applied at a predetermined timing. It has come to be.

  The color image forming apparatus 11 includes a developing device 30 for each color of black (K), transparent color (i) as a special color, cyan (C), magenta (M), and yellow (Y). A toner cartridge 38 that supplies toner of a predetermined color corresponding to each through a flexible tube 31 (shown in FIG. 5) is detachably installed.

  The intermediate transfer belt 32 includes a belt unit drive roll 40, a pair of primary transfer surface-developing rolls 42 and 44 disposed horizontally, and a tension roll (not shown) that applies tension to the intermediate transfer belt 32. ) And a backup roll 48 that is in contact with the secondary transfer roll 46 via the intermediate transfer belt 32 with a constant tension, and a dedicated drive motor (not shown) having excellent constant speed. A drive roll 40 that is rotationally driven by a source) is circulated and driven at a predetermined speed in the direction of the arrow.

  Further, a retracting device 33R is mounted on the driving roll 40 of the belt unit, and the driving roll 40 is moved from the intermediate transfer belt 32 to the image forming units 10K, 12i, 14C, 16M, and 18Y from the intermediate transfer belt 32. It is configured to be movable to the retracted position shown in FIG. 4 for separation. The retracting device 33R may be configured to communicate with the above-described retracting devices 33C, 33M, and 33Y and be simultaneously driven and controlled.

  In this digital color image forming apparatus 11, instead of providing the retracting device 33R for moving the drive roll 40, the intermediate transfer belt 32 is moved to the intermediate transfer belt 32 by a moving operation means (not shown). The transfer operation position shown in FIG. 3 and the retracted position shown in FIG.

  In this color image forming apparatus, each of black (K), multiple transparent colors (i), cyan (C), magenta (M), and yellow (Y) as a special color transferred onto the intermediate transfer belt 32 is obtained. The toner image is secondarily transferred onto a recording sheet (not shown) as an image output medium by a secondary transfer roll 46 that is in pressure contact with the backup roll 48 with a pressure contact force and an electric field.

  The recording paper on which the toner images of these colors are transferred is conveyed to a fixing device 50 positioned above. The secondary transfer roll 46 is in pressure contact with the side of the backup roll 48, and secondary-transfers each color toner image onto a recording sheet conveyed upward from below. The recording paper on which the toner images of the respective colors are transferred is subjected to a fixing process with heat and pressure by the fixing device 50 and then discharged onto a discharge tray 52 provided on the upper portion of the color image forming apparatus 11.

  The recording paper of a predetermined size is separated and conveyed from a paper feed tray 54 as a paper feeder, and is supplied to the secondary transfer position of the intermediate transfer belt 32 through the paper conveyance path at a predetermined timing. The toner image is transferred onto the discharge tray 52 after being transferred as described above.

  In the color image forming apparatus 11, at least the image forming unit 12i is configured to be detachable from the apparatus main body. Further, in the digital color image forming apparatus 11, the image forming unit 10K and the image forming unit 12i are configured to be detachable from the apparatus main body as necessary.

  In the digital color image forming apparatus 11, although not shown, one or more image forming units other than the image forming unit 12i may be detachably mounted between the image forming unit 10K and the image forming unit 14C.

  In this digital color image forming apparatus 11, when an invisible image is formed by using the transparent toner as a special color by the image forming unit 12i, the spectral reflectance characteristics of the invisible image, the recording paper, and the visible image are shown in FIG. It shall have the characteristics as illustrated.

  FIG. 7 shows the result of measuring the spectral reflectance by creating a solid image on a recording sheet with transparent toner, creating toner images of cyan (C), magenta (M), and yellow (Y) thereon. . In FIG. 7, the wavelength range of 400 nm to 700 nm is a visible light region that can be seen with the naked eye. In this region, the reflectance of the transparent toner image is higher than that of the YMC toner image, and the transparent toner cannot be observed with the naked eye.

  On the other hand, the region with a wavelength of 700 nm or more is an invisible light region (near-infrared light region) that cannot be seen with the naked eye. With transparent toner, the spectral reflectance rapidly decreases in this region. Since the difference between the two increases rapidly, the invisible image can be read by a specific means.

  As specific reading means, for example, there is one that reads an image with an image sensor having sensitivity to infrared light while irradiating the sheet with illumination having an infrared light component (for example, a halogen lamp). By using the transparent toner as described above, additional information to be hidden can be formed as an invisible image, and an added value such as security and log management can be provided. The transparent toner can be read at any position regardless of the order of printing.

  Further, in this digital color image forming apparatus 11, an invisible image composed of a two-dimensional pattern as exemplified in the enlarged view when recognized by machine reading by infrared light irradiation of FIG. 8A by the image forming unit 12i. It may be formed. This invisible image of a two-dimensional pattern that can be recognized by infrared light is configured to be decoded and converted into digital information by machine reading and captured as a bit information image 15 as illustrated in the schematic diagram of FIG. To do. That is, this invisible image is read as a two-dimensional pattern as shown in FIG. 8A by a reading device such as a CCD, and this is decoded and converted into a bit information image 15 as digital information. It is decoded into audio information, text, image files, application software electronic files, etc. by a method corresponding to the recording format.

  The two-dimensional patterns illustrated in FIGS. 8A and 8B show an example in the case of being formed by a plurality of minute line bitmaps having different rotation angles. Specifically, the inclinations are different from each other. Two types of minute line units 13 having the following are arranged, one of which represents bit information of “0” and the other “1”. A two-dimensional pattern composed of a plurality of minute line bitmaps having different rotation angles is preferably used because noise applied to a visible image is extremely low and a large amount of information can be digitized and embedded with high density.

  Next, in the color image forming apparatus 11, first, a mode in which all of the image forming units 10K, 12i, 14C, 16M, and 18Y are used to form a full color image (chromatic image), and secondly, A mode in which only the image forming unit 10K is used to form a monochrome image, and third, a monochrome image and a special color image (for example, using transparent toner) using the image forming unit 10K and the image forming unit 12i. A description will be given of a configuration in which an invisible image can be controlled to be switched to a mode for forming an image formed by overlapping a visible image.

  In this digital color image forming apparatus 11, as shown in FIG. 9, an exchangeable image forming unit (for example, a central processing unit (CPU) 100 provided for controlling the color image forming apparatus 11 via a bus 102 is provided. The crumb 104 of the image forming unit 12i) is connected so that special color information specifying what special color is associated with the replaceable image forming unit can be detected.

  In the color image forming apparatus 11, a mode indicator 106 is connected to the central processing unit 100 via a bus 102 for a user to instruct switching of a mode related to image formation. The mode indicator 106 is operated by a user to perform a first full-color image (chromatic image), a second monochrome image mode, a third image formation mode, and the like. A desired mode out of a mode in which the unit 10K and the image forming unit 12i are used to form a monochrome image and a special color image (for example, an image formed by superimposing an invisible image on a visible image using a transparent toner). Select to configure as specified.

  In this color image forming apparatus 11, the retracting devices 33i, 33C, 33M, and 33Y and the retracting device 33R for the belt unit driving roll 40 are connected to the central processing unit 100 via the bus 102, respectively. 33i, 33C, 33M, 33Y, and 33R can be controlled to move to the transfer operation position and the retracted position, respectively. At this time, the central processing unit 100 may be configured to collectively control the retract devices 33C, 33M, and 33Y and to control the retract device 33i independently of this.

  In this color image forming apparatus 11, the central processing unit 100 is independently driven by a driving unit 108 for rotating and driving the photosensitive drum 20 of the image forming unit 10 K for black (K) via the bus 102. Connect and configure to be controllable.

  In this color image forming apparatus 11, a driving unit for rotating and driving the photosensitive drum 20 of the image forming unit 12 i for a transparent color (i) as a special color, for example, via the bus 102 to the central processing unit 100. 110 are connected so as to be independently controllable.

  In this color image forming apparatus 11, the photosensitive drums in the image forming units 14C, 16M, and 18Y for cyan (C), magenta (M), and yellow (Y) are connected to the central processing unit 100 via the bus 102. The drive means 112 for rotationally driving each of the 20 and the like is connected and configured so as to be collectively controllable.

  In the color image forming apparatus 11, the driving unit 108, the driving unit 110, and the driving unit 112 may be configured as a driving unit including independent driving motors. Alternatively, the driving means 108, the driving means 110, and the driving means 112 are constituted by a rotational driving force transmission mechanism, and the driving means 108 that is a rotational driving force transmission mechanism is connected to the output shaft of one driving motor, and this driving means. 108 and the driving means 110 which is a rotational driving force transmission mechanism, and between the driving means 110 and the driving means 112 which is a rotational driving force transmission mechanism, a clutch is provided, and only the driving means 108 is driven. When driving, the clutch between the driving means 108 and the driving means 110 is disconnected, and when driving only the driving means 108 and the driving means 110, the clutch between the driving means 108 and the driving means 110 is connected and the driving means 110 is connected. And the drive means 112 are disengaged, and all of the drive means 108, the drive means 110, and the drive means 112 are connected. May be configured to control so as to connect these two clutches are both when the dynamic.

  Next, in the digital color image forming apparatus 11 configured as described above, a mode for forming a first full-color image (a chromatic color image), a mode for forming a second monochrome image, and a third monochrome image A control operation for selecting a desired mode from the image forming mode and the special color image forming mode will be described with reference to FIG.

  In the control for forming an image in the desired mode, the process waits until the power of the digital color image forming apparatus 11 is turned on in step 200, and proceeds to the next step 202 when the power is turned on.

  In step 202, the process waits until the user operates the mode indicator 106 to input a command for specifying the image forming mode. When the command for the image forming mode is input, the process proceeds to the next step 204.

  In step 204, the central processing unit 100 determines from the crumb 104 of the replaceable image forming unit (for example, the image forming unit 12i) what special color is formed by the image forming unit (for example, the special color is transparent). Those that form an image with toner, or special colors such as light magenta for improving graininess, light color toners such as light cyan, red and green toners for widening the color gamut, gold for special uses, Information on the color relating to the toner such as silver is acquired, and the process proceeds to the next step 206.

  In step 206, it is determined whether or not the command input by the mode indicator 106 is the full color image forming mode. If it is determined that the full color image forming mode is selected, the process proceeds to the next step 208.

  In step 208, all the retracting devices 33i, 33C, 33M, and 33Y are moved to the transfer operation position, and the driving unit 108 of the image forming unit 10K, the driving unit 110 of the image forming unit 12i, and the image forming units 14C, 16M, and 18Y. All the driving means 112 are set in a driving state, set to the state illustrated in FIG. 1 in which an image can be formed in full color, and the process proceeds to the next step 210.

  In step 210, the digital color image forming apparatus 11 performs a process of forming a full color image on a recording sheet as an image output medium using all of the image forming units 10K, 12i, 14C, 16M, and 18Y. Proceed to step 212.

  Next, when it is determined in step 206 described above that the command input by the mode indicator 106 is not in the full color image forming mode, the process proceeds to the next step 214.

  In step 214, based on the information acquired from the crumb 104 in step 204, it is determined whether or not the image forming unit 12i for forming an invisible image using transparent toner is attached to the digital color image forming apparatus 11. If it is determined that the image forming unit 12i for forming an invisible image is attached, the process proceeds to the next step 216.

  In step 216, as shown in FIG. 2, only the retracting device 33i corresponding to the image forming unit 12i for invisible image formation is moved to the transfer operation position (the retracting devices 33C, 33M, and 33Y are set to the retracted positions). Then, the driving unit 108 of the image forming unit 10K and the driving unit of the image forming unit 12i are set to the driving state, and the process proceeds to the next step 218.

  In step 218, the digital color image forming apparatus 11 set in the state shown in FIG. 2 uses the image forming units 10K and 12i to form an image in which an invisible image is superimposed on a monochrome image on a recording sheet as an image output medium. Processing to form is performed, and the process proceeds to the next step 212.

  Further, in step 214 described above, the replaceable image forming unit, for example as shown in FIG. 3, in which the image forming unit 12i for invisible image formation is not mounted is replaced with a light color toner (light magenta, If it is determined that the image forming unit 12X corresponds to a toner such as a light cyan toner, a red or green toner for expanding the color gamut, a gold or silver toner for special use, the next step 220 is performed. Proceed to

  In step 220, as shown in FIG. 4, all the retracting devices 33i, 33C, 33M, 33Y are moved to the retracted position, and only the driving means 108 of the image forming unit 10K is set to the driving state. Proceed to

  In step 222, the digital color image forming apparatus 11 set in the state shown in FIG. 4 performs a process for forming a black and white image on a recording sheet as an image output medium using only the image forming unit 10K. Proceed to step 212.

  In step 212, it is determined whether or not the power supply of the digital color image forming apparatus 11 is 0FF. If the power supply is 0FF, this control operation is terminated. If the power supply is not 0FF, the process returns to step 202.

  According to the digital color image forming apparatus 11 configured as described above, it is possible to provide security, improve image quality with special colors, improve color gamut, and the like according to user needs.

  Further, in this digital color image forming apparatus 11, when the invisible image is formed by using the transparent toner in the image forming unit 12i for the purpose of strengthening the security by controlling as described above, the black color is formed even when the monochrome image is formed. An invisible image can be printed simultaneously with (K color).

  Further, at this time, the other cyan (C), magenta (M), and yellow (Y) image forming units 14C, 16M, and 18Y do not need to form an image. Alternatively, in order to prevent developer deterioration, the intermediate transfer belt 32 is separated from the photosensitive drum 20 as an image carrier, and the photosensitive drum 20 and the developing device 30 are stopped (the output may be limited so as to reduce the output). Then, the output of the charging charger 26 as the charging device and the LED print head 28 as the exposure means are also stopped (the output may be limited to reduce the output).

  Next, in the digital color image forming apparatus 11, the image forming unit 10K and the image forming unit 12i are configured to be detachable from the apparatus main body, and these are used by being replaced with one large image forming unit 10LK. 5 will be described.

  This large image forming unit 10LK is suitable for use when the frequency of forming a black and white image is high compared to the case of forming a full-color image. The diameter (outer diameter: 84 mm) of the photosensitive drum 20L is equal to that of the image forming units 14C, 16M, and 18Y for cyan (C), magenta (M), and yellow (Y) that are not frequently used. It has a larger diameter that is at least twice as large as the diameter (outer diameter: 30 mm).

  Since the large image forming unit 10LK is large as a whole, the image forming unit 10K and the image forming unit 12i are removed from the apparatus main body and mounted in a set large space.

  In the large-sized image forming unit 10LK, the primary transfer position where the large-diameter photosensitive drum 20L and the primary transfer roll 22 that is an intermediate transfer member are in contact with each other is the fifth transfer in the conveyance direction of the intermediate transfer belt 32. Installed at the position (transfer position of the image forming unit 10K). This is because, since the large-diameter photosensitive drum 20L is mounted, the developing device 30 adjacent to the fourth transfer position (transfer position of the image forming unit 12i) in the transport direction of the intermediate transfer belt 32 in the digital color image forming apparatus 11 and the like. However, by placing it at the fifth transfer position, the position of the primary transfer roll 22 (so-called inter-engine pitch) is twice the engine pitch of the normal photosensitive drum 20 (integer multiple). )

  In the case of the digital color image forming apparatus 11 having a tandem configuration, the pitch between the engines is set to an integral multiple of the circumferential length of the driving roll 40 that drives the intermediate transfer belt 32 for normal color registration.

  In this digital color image forming apparatus 11, the engine pitch when changed to the large-diameter photosensitive drum 20 </ b> L is twice the normal engine pitch, so that the condition of an integral multiple of the circumference of the drive roll 40 is maintained. As a result, the color registration can be maintained regardless of the change to the large-diameter photosensitive drum 20L.

  In the digital color image forming apparatus 11, when the large image forming unit 10LK is mounted and used, the two toner cartridges 38 for the two image forming units 10K and 12i are removed, and the empty space is formed. A single large-capacity cartridge 38W is loaded by one.

  A flexible tube 31 is used as a replenishment path for each toner from the large capacity cartridge 38W and the toner cartridge 38 to each developing device 30, and this flexible tube 31 is not shown, but a flexible tube having a coil auger disposed therein. Is used.

  Therefore, in the digital color image forming apparatus 11, by replacing the normal image forming units 10K and 12i with the large image forming unit 10LK, the position of the developing device 30 attached to the large image forming unit 10LK is changed to the large diameter photosensitive drum. Even at a position where 20L is lowered by the diameter increase, the toner cartridge 38 or the large-capacity cartridge 38W can be connected to the corresponding developing device 30 by the same flexible tube 31.

  In the digital color image forming apparatus 11, an LED print head 28 is used as an exposure unit (latent image forming unit) in an integrated manner for each of the image forming units 10K, 12i, 14C, 16M, and 18Y. Therefore, in this digital color image forming apparatus 11, the number of image forming units 10K, 12i, 14C, 16M, and 18Y is replaced with the number of large image forming unit 10LK and the number of image forming units 14C, 16M, and 18Y. However, since each LED print head 28 is attached to each unit as an integral structure, the layout inside the main body of the apparatus is not restricted, and it is compactly mounted in a space-saving and high-density manner. It can be configured to make it easier.

  When a digital color image forming apparatus is configured using a laser exposure apparatus, if the number of photoconductors and the diameter of the photoconductor are changed, the optical path is divided and the optical path is blocked. In addition to making it extremely difficult to install a laser exposure apparatus, a 5-color image forming unit and a 4-color large-sized image forming unit using a large-diameter photosensitive body are mounted in a small space in a small space. However, since the size of the exposure apparatus itself is large, it is difficult to reduce the size of the entire apparatus.

  Further, in the digital color image forming apparatus 11, when the large image forming unit 10LK is mounted and used, the large color image forming unit 10LK for black color (K color) which is frequently used in a normal use environment is used. The service life of the large-diameter photosensitive drum 20L is dramatically increased compared to the photosensitive drums 20 in the other cyan (C), magenta (M), and yellow (Y) image forming units 14C, 16M, and 18Y. Further, since toner that is a consumable is supplied from the large-capacity cartridge 38W, the replacement frequency of the large-capacity cartridge 38W is reduced, the maintainability is improved, and long-term reliability can be obtained.

  As described above, the digital color image forming apparatus 11 is mounted with an image forming unit corresponding to a required special color, or by replacing the image forming units 10K and 12i with a long-life large image forming unit 10LK. Can do.

  Further, in the digital color image forming apparatus 11, as described in the configuration shown in FIGS. 1 to 4, the large image forming unit is driven by controlling the retracting devices 33i, 33C, 33M, 33Y, the retracting device 33R and the like. Of course, a monochrome image can be formed using only 10LK, or a full-color image can be formed using the large image forming unit 10LK and the image forming units 14C, 16M, and 18Y.

  Therefore, the digital color image forming apparatus 11 is a small image forming apparatus, but is used as a unit that enables image formation with high image quality and high added value according to user needs, or has a long life and high reliability. It can be used as a unit that enables image formation, and its commercial value can be improved.

  In the digital color image forming apparatus 11 described above, the retraction devices 33i, 33C, 33M, and 33Y, the retraction device 33R, and the like are driven and controlled, so that the image forming units 12i, 14C, 16M, and 18Y installed in a stationary state are controlled. On the other hand, the intermediate transfer belt 32 and the corresponding primary transfer rolls 22 are configured to be separated from each other, but conversely, the intermediate transfer belt 32 and each primary transfer roll 22 are set in a stationary state. The image forming units 12i, 14C, 16M, and 18Y may be selected and driven and controlled so as to be separated from the intermediate transfer belt 32 side or contacted to the intermediate transfer belt 32 side.

  In the above-described embodiment, the intermediate transfer body type image forming apparatus has been described as an example. However, the present invention is not limited to this, and for example, each image is output to an image output medium conveyed by a paper conveyance belt. The present invention can also be applied to an image forming apparatus that directly transfers an image formed by a forming unit. Further, the present invention is not limited to the above-described embodiments, and it is needless to say that various other configurations can be taken without departing from the gist of the present invention.

1 is an overall schematic configuration diagram illustrating an image forming apparatus in a full-color image forming state according to an embodiment of the present invention. 1 is an overall schematic configuration diagram illustrating an image forming apparatus in a monochrome image forming state in which a special color image is added according to an embodiment of the present invention. 1 is an overall schematic configuration diagram illustrating an image forming apparatus in a state in which a special color image forming unit is replaced to form a full color image according to an embodiment of the present invention. 1 is an overall schematic configuration diagram illustrating an image forming apparatus in a state of forming only a black and white image according to an embodiment of the present invention. 1 is an overall schematic configuration diagram illustrating an image forming apparatus in a state of forming a full color image using a large image forming unit according to an embodiment of the present invention. FIG. 2 is a configuration diagram showing a cross-section of a main part of an image forming unit used in the image forming apparatus according to the embodiment of the present invention. 5 is a graph for explaining the characteristics of an invisible image formed by the image forming apparatus according to the embodiment of the present invention. (A) is an enlarged view of the main part showing an example of an invisible image of a two-dimensional pattern that can be recognized by infrared light formed by the image forming apparatus according to the embodiment of the present invention, and (B) It is a schematic diagram when an invisible image of a two-dimensional pattern is decoded and converted into digital information by machine reading and is regarded as a bit information image. In the image forming apparatus according to the embodiment of the present invention, a control unit capable of switching control between a mode for forming a full color image, a mode for forming only a monochrome image, and a mode for forming a monochrome and special color image. It is a block diagram which shows a structure. 6 is a flowchart showing a control procedure for switching between a mode for forming a full-color image, a mode for forming only a monochrome image, and a mode for forming a monochrome and special color image in the image forming apparatus according to the embodiment of the present invention. .

Explanation of symbols

10K image forming unit 10LK large image forming unit 11 color image forming apparatus 12i image forming unit 12X image forming unit 14C image forming unit 20 photoconductor drum 20L large diameter photoconductor drum 22 primary transfer roll 24 cleaning device 26 charging charger 28 LED print Head 30 Developer 31 Flexible tube 32 Intermediate transfer belt 33i Retracting device 33C Retracting device 33M, Retracting device 33Y Retracting device 33R Retracting device 38 Toner cartridge 38W Large capacity cartridge 46 Secondary transfer roll

Claims (6)

A black color image forming unit; a cyan color image forming unit; a magenta color image forming unit; a yellow color image forming unit; and one or more special color image forming units. A tandem type image forming apparatus capable of forming a full-color image on an image output medium in which a toner image is conveyed to an intermediate transfer unit or a paper conveyance unit ;
At least the special color image forming unit can be replaced with an image forming unit of a different special color type, and can be mounted.
Only the black color image forming unit is placed on the image output medium transported to the intermediate transfer unit or the paper transport unit according to the type of special color in the mounted special color image forming unit. The toner image is transferred by separating the other image forming units by rolling, or the other image is formed by rolling only the black color image forming unit and the one or more special color image forming units. In an image forming apparatus for transferring a toner image by separating a forming unit ,
A diameter of a photosensitive drum provided in the black image forming unit, the black color image forming unit and the special color image forming unit disposed adjacent to the black color image forming unit. An image forming apparatus comprising: a large image forming unit provided with a large-diameter photosensitive drum having a larger diameter than the image forming unit. The image forming apparatus according to claim 1, wherein the image forming unit for the special color forms a transparent toner image having an absorption region in invisible light . The image forming apparatus according to claim 1 , wherein an LED print head is integrated into the image forming unit. The black image forming unit and the special color image forming unit exchanged with the transfer position of the large image forming unit with respect to the image output medium conveyed to the intermediate transfer unit or the sheet conveying unit. 4. The transfer position corresponding to the downstream side in the moving direction of the image output medium conveyed to the intermediate transfer unit or the paper conveyance unit is set to any one of the above-mentioned items. The image forming apparatus described in the item. Claim 4 pitches of the transfer position of the other of said image forming unit adjacent the transfer position of the large image forming unit, characterized in that an integral multiple of the pitch of the transfer position of the other image forming units The image forming apparatus described in 1. Two toners arranged adjacent to each other to supply toner to the black color image forming unit and the special color image forming unit exchanged when the large image forming unit is mounted. The cartridge is removed, a large-capacity cartridge is loaded in the space corresponding to two toner cartridges, and the toner is supplied from the large-capacity cartridge to the developing device provided in the large-size image forming unit via a flexible tube. the image forming apparatus according to any one of claims 1 to 5, characterized by being configured to.

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