JP5941397B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as an electrophotographic printer or a copying machine.

  2. Description of the Related Art Conventionally, as described in Patent Document 1, for example, an electrophotographic recording type image forming apparatus that forms an image by fixing toner on a predetermined printing medium is known. Such an image forming apparatus is configured to charge and expose a photosensitive drum, supply toner from a supply roller to a developing roller, develop an electrostatic latent image formed on the photosensitive drum with toner on the developing roller, and obtain the obtained toner. The image is formed through a process of transferring onto a print medium held by a transfer belt and further fixing the toner image on the print medium.

  In this image forming apparatus, when printing on a transparent film as a printing medium, a photosensitive drum of white (hereinafter referred to as “W”) toner is disposed on the most downstream side, and the W toner is transferred to the back of the color image. A printed image with high brightness was obtained.

JP 2007-83634 A

  However, in the conventional image forming apparatus, if the photosensitive drum of W toner is arranged on the most downstream side, the W toner image cannot be transferred first as a base image on the printing medium, and the photosensitive drum needs to be moved. It was disadvantageous and inconvenient.

An image forming apparatus according to the present invention includes a first image forming unit that is disposed in an image forming region and generates a color developer image, and a spot color that is disposed in the image forming region and has a color different from that of the color developer image. A second image forming unit that forms a developer image; and the color developer image formed by the first image forming unit and disposed opposite to the first image forming unit and the second image forming unit. A transfer unit that transfers the spot color developer image formed by the second image forming unit onto a print medium; and the color developer image and the spot color developer image that are transferred onto the print medium by the transfer unit. According to a printing mode for selecting a stacking order of the color developer image and the special color developer image set according to the type of the print medium, Second image formation Wherein the selectively separated contact disjunction means and a transfer portion, according to the print mode, and a, a loop carrier means capable multiple loops conveying the print medium in the image forming region and. The type of the print medium includes plain paper and transfer paper, the spot color developer image includes a developer image of W, and when the plain paper is used, the developer image of W is In the case where the transfer paper is formed under the color developer image and the transfer paper is used, the W developer image is formed on the color developer image.

Another image forming apparatus of the present invention includes a first image forming unit that is disposed in an image forming area and generates a color developer image, and a color that is disposed in the image forming area and is different from the color developer image. A second image forming unit for forming a special color developer image, and the color developer formed by the first image forming unit disposed opposite to the first image forming unit and the second image forming unit. A transfer unit that transfers the image and the spot color developer image formed by the second image forming unit onto a print medium; the color developer image that is transferred onto the print medium by the transfer unit; and the spot color development The first image formation according to a fixing mode for fixing the agent image, and a printing mode for selecting a stacking order of the color developer image and the special color developer image set according to the type of the print medium And the second image A separating / contacting unit that selectively separates and contacts the forming unit and the transfer unit, and a loop transporting unit capable of loop transporting the print medium a plurality of times in the image forming region according to the printing mode, Types of print media include plain paper and transfer paper, the spot color developer image includes a W developer image, and when the plain paper is used, the W developer image is replaced with the color developer. In the image forming apparatus, the W developer image is formed on the color developer image when the transfer paper is used under the image. The printing apparatus has another printing mode for increasing the density of the W developer image.

  According to the present invention, the user can print on different types of print media without exchanging the first image forming unit and the second image forming unit, and can work efficiently. Further, since the first image forming unit and the second image forming unit and the transfer unit are selectively separated from each other, useless idle rotation and useless transfer processes are eliminated, so that the first image forming unit and the second image forming unit are eliminated. It is possible to obtain an image similar to that obtained by replacing the, and prolong the life.

FIG. 1 is a schematic cross-sectional view showing the structure of an image forming apparatus in Embodiment 1 of the present invention. FIG. 2A is a schematic configuration diagram illustrating the separation / contact mechanism of the image forming unit batch movement method which is the first method of the separation / contact mechanism 50. FIG. 2B is a schematic configuration diagram showing a transfer unit moving type separation / contact mechanism that is a second method of the separation / contact mechanism 50. FIG. 2C is a schematic configuration diagram showing an image forming unit individual movement type separation / contact mechanism that is a third method of the separation / contact mechanism 50. FIG. 3 is a block diagram showing a control system of the image forming apparatus 1 of FIG. FIG. 4 is a diagram showing an example of the print mode setting screen 65b stored in the ROM 65 in FIG. FIG. 5 is a diagram showing an example of the print medium / print mode correspondence table 65c stored in the ROM 65 in FIG. FIG. 6 is a diagram for explaining plain paper printing and transfer paper printing. FIG. 7 is a flowchart showing a printing operation in the image forming apparatus 1 shown in FIGS. FIG. 8 is a schematic configuration diagram showing a plurality of image forming units and a transfer unit, which are the main parts of the image forming apparatus according to the second embodiment of the present invention. FIG. 9 is a flowchart showing a printing operation in the image forming apparatus 1A of FIG. FIG. 10 is a schematic configuration diagram showing a plurality of image forming units and transfer units, which are the main part of the image forming apparatus 1A, which is the first modification of FIG. FIG. 11 is a schematic configuration diagram showing a plurality of image forming units and transfer units, which are a main part of the image forming apparatus 1A, which is the second modification of FIG. FIG. 12 is a schematic configuration diagram showing a plurality of image forming units and transfer units, which are the main part of the image forming apparatus 1A, which is the third modification of FIG. FIG. 13 is a schematic configuration diagram showing a plurality of image forming units and transfer units, which are the main part of the image forming apparatus 1A, which is the fourth modification of FIG. FIG. 14 is a schematic configuration diagram showing a plurality of image forming units and transfer units, which are the main parts of the image forming apparatus 1A, according to the fifth modification of FIG. FIG. 15 is a diagram showing a list of relationships between the separation from the transfer belt 21 and the transfer time when the T image forming unit 10T or the W image forming unit 10W is arranged on the most upstream side or the most downstream side in the print medium conveyance direction. is there. FIG. 16 is a diagram illustrating an example of a print mode setting screen 65B in the image forming apparatus according to the third embodiment of the present invention. FIG. 17 is a flowchart illustrating a printing operation in the image forming apparatus 1B according to the third exemplary embodiment. FIG. 18 is a diagram illustrating experimental results of Examples 1 and 2 and Modifications 1 to 5 and Example 3.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Configuration of Example 1)
FIG. 1 is a schematic cross-sectional view showing the structure of an image forming apparatus in Embodiment 1 of the present invention.

  The image forming apparatus 1 is, for example, a tandem method capable of printing four colors of cyan (hereinafter referred to as “C”), magenta (hereinafter referred to as “M”), yellow (hereinafter referred to as “Y”), and W. This is an electrophotographic printer. In the first embodiment, four colors C, M, Y, and W will be described, but five colors of black (hereinafter referred to as “K”), Y, M, C, and W may be used. .

  The image forming apparatus 1 according to the first exemplary embodiment includes a housing 1a that accommodates the entire apparatus. A detachable paper cassette 2 as a print medium cassette is mounted in the lower part of the housing 1a. A plurality of print media 3 are accommodated in the paper cassette 2 in a stacked state. As the print medium 3, for example, colored plain paper 3a or transfer paper 3b is used. The colored plain paper 3a is plain paper such as K, blue, red, etc. with a color other than W color. The transfer paper 3b is a medium for transferring to a T-shirt or the like. The transfer paper 3b is used by transferring a toner image formed thereon with toner 17 as a developer onto a T-shirt or the like with heat from an iron or the like after fixing.

  A paper feed roller 4 is provided at the upper end on the front end side of the paper cassette 2. The paper feed roller 4 is rotated in the counterclockwise direction x1 indicated by the arrow in FIG. 1 by a motor or the like to separate the print medium 3 from the paper cassette 2 one by one and take it out in the conveyance direction y indicated by the arrow in FIG. It is. A transport roller unit 5 is provided above the paper feed roller 4 and downstream of the transport direction y of the print medium 3. The transport roller unit 5 is rotated by a motor or the like and pulls out the taken out print medium 3, and a position detection sensor 6 is provided in the vicinity of the downstream side.

  The position detection sensor 6 detects the leading position of the drawn print medium 3, and on the downstream side thereof, a suction roller 7 and a four-color image forming unit 10 (for example, C as a first image forming unit). An image forming unit 10C, a Y image forming unit 10Y and an M image forming unit 10M, a W image forming unit 10W as a second image forming unit, and a transfer unit 20 as a transfer unit are provided. The suction roller 7 is for sucking the print medium 3 to the transfer belt 21 in the transfer unit 20.

  The four-color image forming unit 10 includes a C image forming unit 10C, a Y image forming unit 10Y, and an M image forming unit 10M as a first image forming unit that forms a color (C, Y, M) toner image, and its color. A (C, Y, M) toner image having a W image forming unit 10W as a second image forming unit for forming a special color toner image having a color (for example, W) different from that of the toner image, and these are arranged in the image forming region PF Has been.

  Each color image forming unit 10 (= 10C, 10Y, 10M, 10W) has the same configuration. For example, the C image forming unit 10C rotates in the clockwise direction z indicated by an arrow in FIG. 1, and the photosensitive drum 11C as an electrostatic latent image carrier that carries an image as an electrostatic latent image, and the photosensitive drum 11C. The charging roller 12 as charging means for uniformly charging the photosensitive drum 11C and the photosensitive drum 11C, and the electrostatic latent image formed on the surface of the photosensitive drum 11C. A developing roller 13 as a developer carrying member to be developed, a supply roller 14 as a developer supply means for supplying toner 17 (= 17C, 17Y, 17M, 17W) to the developing roller 13, and a contact with the developing roller 13 The toner 17 on the developing roller 13 is a layer forming blade 15 as a layer forming means for forming a uniform toner layer, and the toner 17 is stored and supplied to the supply roller 14. And removable toner tank 16 such as a developing agent storage unit is constituted by.

  The C toner 17C is stored in the toner tank 16 in the C image forming unit 10C, the Y toner 17Y is stored in the toner tank 16 in the Y image forming unit 10Y, and the toner tank 16 in the M image forming unit 10M is stored. The M toner 17M is stored in the toner tank 16 in the W image forming unit 10W.

  Each photosensitive drum 11 (= 11C, 11Y, 11M, 11W), each developing roller 13 and each supply roller 14 is provided with a gear (not shown) at one end, and each developing roller 13 and each supply roller 14 are engaged with the gears of the respective photosensitive drums 11 (= 11C, 11Y, 11M, and 11W) and are driven to rotate.

  In the vicinity of the image forming unit 10C, a light emitting element (hereinafter referred to as “LED”) head 18C as an exposure unit is provided. The LED head 18C exposes the surface of the photosensitive drum 11C to form an electrostatic latent image on the photosensitive drum 11C.

  The other Y, M, and W image forming units 10Y, 10M, and 10W have the same configuration including the photosensitive drums 11Y, 11M, and 11W, as in the C image forming unit 10C. Further, LED heads 18Y, 18M, and 18W are provided in the vicinity of the image forming units 10Y, 10M, and 10W, respectively.

  Here, each color toner 17 stored in each toner tank 16 includes, for example, a polyester resin, a colorant, a charge control agent, and a release agent, and an external additive (hydrophobic silica) is added. Thus, a developer having an average particle diameter of 8 μm obtained by a pulverization method is used. The C, M, and Y colorants are mixed to create a color, so that a somewhat transparent pigment is used, and the W colorant is an opaque colorant. Each color developing roller 13 is formed of an elastic body on the outer periphery of a metal shaft. As these developing rollers 13, for example, semiconductive urethane rubber having a rubber hardness of 70 ° (Asker C) is used as an elastic body on a metal shaft. Each color supply roller 14 is formed of a foam on the outer periphery of a metal shaft. As these supply rollers 14, for example, a silicon foam having a hardness of 50 ° (Asker F) is formed on a metal shaft.

  A transfer unit 20 is disposed at a position facing the lower side of the four-color image forming unit 10 (= 10C, 10Y, 10M, 10W). The transfer unit 20 transfers the toner image formed by the image forming unit 10 (= 10C, 10Y, 10M, 10W) for each color onto the print medium 3. The transfer unit 20 includes an endless transfer belt 21 that conveys the print medium 3, a driving roller 22 that rotates in the counterclockwise direction x2 indicated by an arrow in FIG. A driven roller 23 provided at the other end of the transfer belt 21 and rotated in the counterclockwise direction x2 indicated by an arrow in FIG. 1 by being driven by the drive roller 22 and the photosensitive drums 11 ( = 11C, 11Y, 11M, and 11W), and transfer rollers 24 (= 24C, 24Y, 24M, and 24W) for each color as transfer means. Each color transfer roller 24 is applied with a predetermined voltage to transfer the toner image on each photoconductive drum 11 to the print medium 3.

  In the image forming region PF, a fixing unit 30 as a fixing unit is provided on the downstream side of the W image forming unit 10W. The fixing unit 30 heats and pressurizes the toner image transferred onto the print medium 3 to fix it on the print medium 3. The heating roller 31 and the pressure roller that are in pressure contact with each other with the print medium 3 interposed therebetween. 32 or the like. The heating roller 31 has a heating element such as a halogen lamp inside, for example, and heats the printing medium 3. The pressure roller 32 presses the heating roller 31 via the print medium 3 and fixes the toner image on the print medium 3.

  A separator 33 is provided on the downstream side of the fixing unit 30. The separator 33 is a member for switching whether to supply the print medium 3 on which the toner image is fixed again to the image forming area PF (that is, to refeed) or to discharge the print medium 3 to the outside. is there. A discharge roller unit 34 and a discharge cassette 35 are provided on the discharge path side of the print medium 3. The discharge roller unit 34 discharges the print medium 3 to the discharge cassette 35. The discharge cassette 35 is provided in the upper part of the housing 1 a and accommodates the print medium 3 discharged from the discharge roller unit 34.

  On the refeed path side of the print medium 3, a refeed unit 40 is provided as a loop transport unit. The refeed unit 40 loops the print medium 3 to the image forming area PF without changing the first print surface and the second print surface of the print medium 3 switched by the separator 33. The refeed unit 40 includes a conveyance roller pair 41 that takes in the print medium 3 switched by the separator 33, a refeed path 42 that carries the taken print medium 3 toward the carry roller unit 5, and the like. Has been.

  In such an image forming apparatus, as shown in FIGS. 2-1 (a), (b), FIGS. 2-2 (a) to (c), and FIG. 2-3, a plurality of image forming units 10 ( = 10C, 10Y, 10M, 10W) and a separation / contact mechanism 50 as a separation / contact mechanism for separating / contacting the transfer unit 20 is provided.

  There are three types of separation / contact mechanism 50. The first method is an image forming unit batch movement method in which all the image forming units 10 (= 10C, 10Y, 10M, 10W) are moved up and down at a time with respect to the fixed transfer unit 20. The second method is a transfer unit moving method in which all the image forming units 10 (= 10C, 10Y, 10M, and 10W) are fixed and the transfer unit 20 is moved up and down (that is, rotated up and down). . Further, the third method is an individual image forming unit moving method in which each image forming unit 10 is individually moved up and down with respect to the fixed transfer unit 20.

  FIGS. 2-1 (a) and (b) are schematic configuration diagrams showing an image forming unit batch movement type separation / contact mechanism which is a first method of the separation / contact mechanism 50 of FIG.

  The separation / contact mechanism 50 in FIG. 2A moves the rollers 19 (= 19C, 19Y, 19M, and 19W) attached to the lower portions of the image forming units 10 (= 10C, 10Y, 10M, and 10W) of the respective colors up and down. A rod-like linear motion cam 51 for moving, a lift up link 52 for causing the linear motion cam 51 to reciprocate linearly in the horizontal direction, and one end of the linear motion cam 51 attached to the lift up link 52. The moving part 53 etc. for reciprocating the part 51c are comprised. On the upper surface of the linear motion cam 51, a plurality of concave portions 51a for receiving the respective rollers 19 (= 19C, 19Y, 19M, 19W) and a plurality of convex portions 51b positioned between the concave portions 51a are formed. Yes. One end 51 c of the linear cam 51 is connected to the lift-up link 52.

  In the separating / connecting mechanism 50 having such a configuration, as shown in FIG. 2A, the linear cam 51 is moved in the right direction of the broken line arrow via the lift-up link 52 by the driving force of the moving unit 53. Then, the three rollers 19C, 19Y, 19M on the three C, Y, M image forming units 10C, 10Y, 10M side are pushed up by the convex portions 51b of the linear cam 51, and the three image forming units 10C. , 10Y, 10M move upward in the direction of the solid arrow and are separated from the transfer unit 20. The roller 19W on the W image forming unit 10W side falls into the concave portion 51a of the linear cam 51, so that the image forming unit 10W falls and contacts the transfer unit 20.

  Also, as shown in FIG. 2B, when the linear cam 51 moves to the left of the broken line arrow by the driving force of the moving unit 53, the three image forming units 110C, C, Y, C Since the three rollers 19C, 19Y, and 19M on the 10Y and 10M sides fall into the respective concave portions 51a of the linear motion cam 51, the image forming portions 10C, 10Y, and 10M fall and come into contact with the transfer unit 20. The roller 19 </ b> W on the W image forming unit 10 </ b> W side is pushed up by each convex portion 51 b of the linear motion cam 51, and the image forming unit 10 </ b> W moves upward from the solid line arrow and is separated from the transfer unit 20. When the linear cam 51 further moves to the left, the three rollers 19C, 19Y, and 19M move in the concave portions 51a of the linear cam 51, and the roller 18W falls into the concave portion 51a of the linear cam 51 to form an image. Since the portion 10W falls, all the image forming portions 10C, 10Y, 10M, and 10W come into contact with the transfer unit 20.

  FIGS. 2-2 (a) to (c) are schematic configuration diagrams showing a separation / contact mechanism of a transfer unit moving system which is a second system of the separation / contact mechanism 50 of FIG.

  In the separation / contact mechanism 50 of FIG. 2B, the drive roller 22 side and the driven roller 23 side of the transfer unit 20 are moved up and down with respect to all the image forming units 10 (= 10C, 10Y, 10M, 10W). It has a configuration to let you. Each image forming unit 10 is biased downward by a biasing means such as a spring, and is configured to be movable up and down within a predetermined range (for example, about several mm to several tens of mm).

  In the state shown in FIG. 2-2 (a), both the driving roller 22 side and the driven roller 23 side of the transfer unit 20 are lifted upward by the separation / contact mechanism 50, and the transfer unit 20 is moved to all the image forming units 10 (= 10C, 10Y, 10M, 10W). In the state shown in FIG. 2B, the drive roller 22 side of the transfer unit 20 is pushed down in the direction of the solid arrow by the separation / contact mechanism 50, and only the driven roller 23 side of the transfer unit 20 is the W image forming unit. The other part of the transfer unit 20 is separated from the C, Y, M image forming units 10C, 10Y, 10M. In the state shown in FIG. 2-2 (c), the driven roller 23 side of the transfer unit 20 is pushed down in the direction of the solid arrow by the separation / contact mechanism 50, and only the driven roller 23 side of the transfer unit 20 is the W image forming unit. Separated from 10W. At this time, other portions of the transfer unit 20 are in contact with the C, Y, M image forming units 10C, 10Y, 10M biased downward.

  FIG. 2C is a schematic configuration diagram illustrating a separation / contact mechanism of an image forming unit individual movement method which is a third method of the separation / contact mechanism 50 of FIG. 1.

  In the separation / contact mechanism 50 in FIG. 2-3, each image forming unit 10 (= 10C, 10Y, 10M, 10W) is individually moved in the vertical direction of the solid line arrow with respect to the fixed transfer unit 20. It has become.

FIG. 3 is a block diagram showing a control system of the image forming apparatus 1 of FIG.
The control system of the image forming apparatus 1 operates by receiving a drive voltage from the power supply unit 100, and prints based on the print data D101 supplied from the host device 101 as information input means such as a personal computer (PC). It is configured to control the operation. The image forming apparatus 1 includes an interface unit 61 that exchanges information such as print data D101 with the host device 101, and a print control unit 62 serving as a print control unit is connected to the interface unit 61. ing.

  The print control unit 62 controls the overall operation of the image forming apparatus 1. The print control unit 62 includes an operation input unit 63 such as an input display panel, various sensors 64 for detecting the print medium 3, a memory (for example, a read-only memory, hereinafter referred to as “read-only memory”). ROM ”) 65, a memory for storing working data (for example, a readable / writable memory, hereinafter referred to as“ RAM ”) 66, and a central processing unit (hereinafter referred to as“ CPU ”) 67 are connected to each other. Has been. The CPU 67 is a device that controls reading and writing (that is, access) to the ROM 65 and the RAM 66, and gives a control signal to the print control unit 62 according to a printing operation program 65 a stored in the ROM 65. The print control unit 62 controls the entire image forming apparatus 1 based on the control signal. In the ROM 65, in addition to the print operation program 65a, the data of the print mode setting screen 65b, the print medium / print mode correspondence table 65c as the print medium / print mode correspondence information indicating the correspondence between the print medium 3 and the print mode, A motor table 65d for motor control, a temperature table 65e for temperature control, and the like are stored.

  The print control unit 62 further includes a process control unit 68 that controls the voltage of each roller, a developing roller 13 that constitutes a developing unit in the image forming unit 10, a supply roller 14, and a layer forming blade 15. A development voltage control unit 69 that controls the development voltage in the development roller 13, a supply voltage control unit 70 that controls the supply voltage in the supply roller 14, and a layer formation voltage control unit 71 that controls the layer formation voltage in the layer formation blade 15 The charging voltage control unit 72 for controlling the charging voltage in the charging roller 12, the exposure control unit 73 for controlling the LED heads 18 (= 18C, 18Y, 18M, 18W), and the photosensitive drums 11 (= 11C, 11Y). , 11M, 11W), a motor control unit 74 for controlling the photosensitive drum motor 74a for rotationally driving, and a drive motor 7 for rotationally driving the drive roller 22. motor control unit 75 for controlling a, transfer roller control unit 76 for controlling each transfer roller 24 (= 24C, 24Y, 24M, 24W), heating roller control unit 77 for controlling heating roller 31, and separation / contact mechanism A separation / contact control unit 78 that controls the operation of 50 and a position sensor control unit 79 that controls the position sensor 6 are connected.

  FIG. 4 is a diagram showing an example of the print mode setting screen 65b stored in the ROM 65 in FIG.

  In this print mode setting screen 65b, a print medium list 65b-1 for selecting either the colored plain paper 3a or the transfer paper 3b as the print medium 3, and an OK for saving the setting (hereinafter referred to as “OK”). ) Button 65b-2 and a cancel button 65b-3 for canceling the setting contents.

  FIG. 5 is a diagram showing an example of the print medium / print mode correspondence table 65c stored in the ROM 65 in FIG.

  When colored plain paper 3 a is used as the print medium 3, the print mode MD is “print W toner image under color toner image”. When the transfer paper 3b is used, the print mode MD is “print a W toner image on a color toner image”.

  FIGS. 6A and 6B are diagrams for explaining plain paper printing and transfer paper printing. FIG. 6A is an explanatory diagram for printing on colored plain paper 3a, and FIG. ) Is an explanatory diagram for printing on the transfer paper 3b.

  6A, when the color (C, Y, M) toner image 47FC is printed on the colored plain paper 3a (for example, the blue plain paper), the colored plain paper 3a and the color toner image FC are printed. If the W toner image 47W is printed between the two, the original color can be reproduced without being affected by the background because the W toner image 47W is an opaque image.

  6B, for example, when printing a color (C, Y, M) toner image 47FC on a blue T-shirt 48, the color toner image 47FC is printed on the transfer paper 3b. A W toner image 47W is printed on the color toner image 47FC. Then, the surface of the W toner image 47W is placed on the blue T-shirt 48, heat 49 is applied to transfer the W toner image 47W to the blue T-shirt 48, and then the transfer paper 3b is moved to the direction indicated by the arrow in FIG. When peeled upward, an inverted image of the color toner image 47FC is printed on the blue T-shirt 48.

(Operation of Example 1)
FIG. 7 is a flowchart showing a printing operation in the image forming apparatus 1 of FIGS.

  In the image forming apparatus 1 according to the first embodiment, as shown in FIGS. 6A and 6B, the operation differs between when printing on the transfer paper 3b and when printing on the colored plain paper 3a. The operation (I) for printing on the transfer paper 3b and the operation (II) for printing on the colored plain paper 3a will be described separately.

(I) Operation when Printing on Transfer Paper 3b In the flowchart of FIG. 7, when the printing operation is started and the image forming apparatus 1 is turned on in step S1, the CPU 67 in FIG. The printing operation program 65 a is read and a control signal according to the program 65 a is given to the printing control unit 62. The print control unit 62 controls the entire image forming apparatus 1 based on the control signal given from the CPU 67 and executes the processes of steps S2 to S16 in the flowchart of FIG.

  In step S2, the separation / contact control unit 78 controlled by the print control unit 62 in FIG. 3 controls the operation of the separation / contact mechanism 50 to transfer all the image forming units 10C, 10Y, 10M, and 10W to the transfer belt 21. Contact is made, and a standby state of step S3 is entered. In step S3, the display unit of the host apparatus 101 in FIG. 3 prompts the user to input the print mode MD. When the user operates the host apparatus 101, the data of the print mode setting screen 65b of FIG. 4 stored in the ROM 65 is called up by the control of the CPU 67 via the interface unit 61 and the print control unit 62, and the print control unit 62 and The print mode setting screen 65b is displayed on the display unit of the host apparatus 101 via the interface unit 61. When the user selects the transfer sheet 3b from the print medium list 65b-1 and presses the OK button 65b-2 on the print mode setting screen 65b of FIG. 4 displayed on the display unit of the upper level apparatus 101, the user selects the transfer sheet 3b. The selection information is sent to the print control unit 62 via the interface unit 61. When the print medium 3 is selected, the CPU 67 causes the CPU 67 to call the print medium / print mode correspondence table 65c of FIG. 5 from the ROM 65, and print “W toner image on color (CYM) toner image. The print mode MD is operated, and the process proceeds to step S4.

  In step S4, as shown in FIG. 6B, the print control unit 62 is in the print mode MD for printing the W toner image 47W on the color (C, Y, M) toner image 47FC (YES). The process proceeds to step S5. In step S5, when the print control unit 62 receives a print instruction from the host apparatus 101 via the interface unit 61, the C, Y, M image forming units 10C, 10Y, and 10M perform color (C, Y, M) toner. Control is performed to transfer the image 47FC to the transfer paper 3b.

  That is, since the print control unit 62 causes the CPU 67 to read the motor table 65d from the ROM 65 and print the transfer paper 3b, the motor control unit 75 drives the drive motor 75a to drive the drive roller 22 at a predetermined speed. Rotate. For example, the transfer belt 21 is operated at 46 mm / s by the driving roller 22 at a printing speed of 10 PPM. Further, the print controller 62 drives the photosensitive drum motor 74a by the motor controller 74 to rotate the photosensitive drums 11C, 11Y, and 11M, and the developing rollers 13 and the supply rollers 14 by motors (not shown). Rotate. When each photoconductor drum 11C, 11Y, 11M rotates, each charging roller 12 rotates with each photoconductor drum 11C, 11Y, 11M and charges the surface of each photoconductor drum 11C, 11Y, 11M.

  When the surfaces of the photosensitive drums 11C, 11Y, and 11M are charged, the LED heads 18C, 18Y, and 18M are imaged on the charged photosensitive drums 11C, 11Y, and 11M under the control of the exposure control unit 73. An electrostatic latent image based on the data is formed. When the electrostatic latent images are formed on the surfaces of the photosensitive drums 11C, 11Y, and 11M, the color toners 17C, 17Y, and 17M held by the supply rollers 14 are supplied to the surfaces of the development rollers 13. When the color toners 17 </ b> C, 17 </ b> Y, and 17 </ b> M on the surface of each developing roller 13 pass through each layer forming blade 15, the layer thickness is regulated and becomes uniform by the shearing force of each layer forming blade 15. When the surfaces of the developing rollers 13 to which the color toners 17C, 17Y, and 17M, which are uniformly regulated, are attached to the surfaces of the photosensitive drums 11C, 11Y, and 11M, the photosensitive drums 11C, 11Y, and 11M are contacted. The color toners 17C, 17Y, and 17M are respectively developed on the upper electrostatic latent image.

  On the other hand, when the drive motor 75a is driven and the drive roller 22 is rotated under the control of the motor control unit 75, the driven roller 23 is rotated and the transfer belt 21 is rotated. The transfer paper 3b, which is the printing medium 3 in the paper cassette 2, is fed in the transport direction y by the paper feed roller 4, and then sandwiched by the transport roller unit 5 and controlled by the position sensor control unit 79. The leading position of the transfer paper 3b is detected by the detection sensor 6. Thereafter, the transfer paper 3b is sandwiched between the suction roller 7 and the drive roller 22, is sucked to the transfer belt 21, and is conveyed through the image forming region PF by the transfer belt 21. The color toner images 47C, 47Y, 47M on the surfaces of the photosensitive drums 11C, 11Y, 11M are transferred to the transfer paper 3b by the transfer rollers 24C, 24Y, 24M to which a high voltage is applied from the power supply unit 100. .

  Next, the process proceeds to step S6, where the W toner image 47W is transferred from the W image forming unit 10W onto the color toner image 47FC transferred onto the transfer paper 3b, and the process proceeds to step S7. In step S <b> 7, the heating roller 31 in the fixing unit 30 is heated to a temperature (for example, 160 ° C.) set by the temperature table 65 e in the ROM 65 under the control of the heating roller control unit 77. Therefore, the transfer paper 3b on which the toner images 47FC and 47W have been transferred is sandwiched between the heated heating roller 31 and the pressure roller 32 disposed opposite thereto, and is conveyed. The toner images 47FC and 47W on the transfer paper 3b are heated and pressed by the heating roller 31 and the pressure roller 32, and the toner images 47FC and 47W are fixed on the transfer paper 3b. Thereafter, in step S16, the transfer sheet 3b subjected to the fixing process is discharged from the discharge port by the discharge roller unit 34 and conveyed to the discharge cassette 35, and the printing operation on the transfer sheet 3b is completed.

(II) Operation when Printing on Colored Plain Paper 3a In the flowchart of FIG. 7, the printing operation is started in the same manner as (I). In step S1, the image forming apparatus 1 is powered on, and step S2 Proceed to In step S2, the separation / contact control unit 78 in FIG. 3 controls the separation / contact mechanism 50 to bring all the image forming units 10C, 10Y, 10M, and 10W into contact with the transfer belt 21, and enters the standby state in step S3. .

  In step S3, the display unit of the host apparatus 101 in FIG. 3 prompts the user to input the print mode MD. When the user operates the host apparatus 101, the data of the print mode setting screen 65b of FIG. 4 stored in the ROM 65 is called up by the control of the CPU 67 via the interface unit 61 and the print control unit 62, and the print control unit 62 and The print mode setting screen 65b is displayed on the display unit of the host apparatus 101 via the interface unit 61. When the user selects the colored plain paper 3a from the print medium list 65b-1 and presses the OK button 65b-2 on the print mode setting screen 65b shown in FIG. The selection information for the plain paper 3 a is sent to the print control unit 62 via the interface unit 61. When the print medium 3 is selected, the print control unit 62 causes the CPU 67 to call the print medium / print mode correspondence table 65c of FIG. 5 from the ROM 65, and select “W toner image as color (C, Y, M) toner image”. The printing mode MD is set to “print below”, and the process proceeds to step S4.

  In step S4, as shown in FIG. 6A, the print control unit 62 is the mode MD for printing the W toner image 47W under the color (C, Y, M) toner image 47FC (NO). Proceed to step S8. In step S8, the separation / contact control section 78 controls the separation / contact mechanism 50 (for example, the separation / contact mechanism in FIG. 2-1 (a)), and the C, Y, M image forming sections 10C, 10Y, 10M in FIG. -1 (a) is moved upward in the direction of the arrow to move away from the transfer belt 21, and the process proceeds to step S9. In the separation / contact mechanism 50 of FIG. 2-2 (b), the separation roller 50 lowers the drive roller 22 side of the transfer unit 20 downward in the direction of the arrow, so that the C, Y, M image forming unit 10C, The transfer belt 21 is separated from 10Y and 10M. Also, in the separation / contact mechanism 50 of FIG. 2C, the C / Y / M image forming units 10 </ b> C, 10 </ b> Y, and 10 </ b> M are moved upward in the direction of the arrows and separated from the transfer belt 21. At this time, since the C, Y, M image forming units 10C, 10Y, and 10M have no relation to the printing operation, the development voltage control unit 69, the supply voltage control unit 70, the charging voltage control unit 72, and the layer formation voltage control unit Under the control of 71, no voltage is applied to the developing roller 13, the supply roller 14, the charging roller 12, and the layer forming blade 15 in the C, Y, M image forming units 10C, 10Y, 10M.

  In step S9, when the print control unit 62 receives a print instruction from the host device 101 via the interface unit 61, the print control unit 62 performs control to transfer the W toner image 47W to the colored plain paper 3a by the W image forming unit 10W.

  That is, since the print control unit 62 causes the CPU 67 to read the motor table 65d from the ROM 65 and prints the colored plain paper 3a, the motor control unit 75 drives the drive motor 75a to drive the drive roller 22 to a predetermined level. Rotate at speed. For example, the transfer belt 21 is operated at 130 mm / s by the driving roller 22 at a printing speed of 30 PPM. The print control unit 62 drives the photoconductive drum motor 74a by the motor control unit 74 to rotate the photoconductive drum 11W, and the developing roller 13 and the supply roller 14 in the W image forming unit 10W are driven by a motor (not shown). Rotate. When the photosensitive drum 11W rotates, the charging roller 12 rotates with the photosensitive drum 11W and charges the surface of the photosensitive drum 11W.

  When the surface of the photosensitive drum 11W is charged, the LED head 18W forms an electrostatic latent image based on the image data on the surface of the charged photosensitive drum 11W under the control of the exposure control unit 73. When an electrostatic latent image is formed on the surface of the photosensitive drum 11 </ b> W, W toner 17 </ b> W held by the supply roller 14 is supplied to the surface of the developing roller 13. When the W toner 17 </ b> W on the surface of the developing roller 13 passes through the layer forming blade 15, the layer thickness is regulated and becomes uniform by the shearing force of the layer forming blade 15. When the surface of the developing roller 13 to which the uniformly regulated W toner 17W adheres and the surface of the photosensitive drum 11W come into contact with each other, the W toner image 47W is developed on the electrostatic latent image on the photosensitive drum 11W.

  On the other hand, when the drive motor 75a is driven and the drive roller 22 is rotated under the control of the motor control unit 75, the driven roller 23 is rotated and the transfer belt 21 is rotated. Then, the colored plain paper 3 a which is the printing medium 3 in the paper cassette 2 is fed in the transport direction y by the paper feed roller 4, and then sandwiched by the transport roller unit 5 and controlled by the position sensor control unit 79. The position detection sensor 6 detects the leading position of the colored plain paper 3a. Thereafter, the colored plain paper 3a is sandwiched between the suction roller 7 and the drive roller 22, and is sucked to the transfer belt 21, and is conveyed by the transfer belt 21 to the image forming unit 10W in the image forming area PF. The W toner image 47W on the surface of the photosensitive drum 11W is transferred to the colored plain paper 3a by the transfer roller 24W to which a high voltage is applied from the power supply unit 100, and the process proceeds to step S10.

  In step S <b> 10, the heating roller 31 in the fixing unit 30 is heated to a temperature (for example, 160 ° C.) set by the temperature table 65 e in the ROM 65 under the control of the heating roller control unit 77. For this reason, the colored plain paper 3a to which the W toner image 47W has been transferred is sandwiched between the heated heating roller 31 and the pressure roller 32 disposed opposite thereto, and is conveyed. The W toner image 47W on the colored plain paper 3a is heated and pressed by the heating roller 31 and the pressure roller 32, and the W toner image 47W is fixed to the colored plain paper 3a for the first time. The process proceeds to step S11.

  In step S11, in order to re-feed the colored plain paper 3a, the colored plain paper 3a is looped. That is, the colored plain paper 3a after fixing is distributed to the refeed unit 40 by the separator 33, and the transport roller unit 41 passes through the refeed path 42 by the transport roller pair 41 in the refeed unit 40. 5 and the position detection sensor 6 detects the head of the colored plain paper 3a. Since the re-feed unit 40 wants to transfer to the same surface as the first fixing surface, the colored plain paper 3a is conveyed without being reversed, and the process proceeds to step S12.

  In step S12, the separation / contact control section 78 controls the separation / contact mechanism 50 (for example, the separation / contact mechanism in FIG. 2-1 (b)) to lower the C, Y, M image forming sections 10C, 10Y, 10M. Then, the transfer belt 21 is contacted, and the process proceeds to step S13. In the separation / contact mechanism 50 shown in FIG. 2C, the driven roller 23 side of the transfer unit 20 is moved downward in the direction of the arrow by the separation / contact mechanism 50, so that the C, Y, M image forming unit 10C, 10Y and 10M are brought into contact with the transfer belt 21. Also, in the separation / contact mechanism 50 of FIG. 2-3, the separation / contact mechanism 50 causes the C, Y, M image forming units 10C, 10Y, 10M to descend in the downward direction of the arrow and contact the transfer belt 21.

  In step S13, the separation / contact control section 78 controls the separation / contact mechanism 50 (for example, the separation / contact mechanism in FIG. 2-1 (b)), and moves the W image forming section 10W upward in the direction of the arrow in the drawing. After separating from the belt 21, the process proceeds to step S14. In the separation / contact mechanism 50 of FIG. 2C, when the driven roller 23 side of the transfer unit 20 is lowered in the arrow downward direction by the separation / contact mechanism 50, the transfer belt 21 is moved from the W image forming unit 10W. Separate. Also, in the separation / contact mechanism 50 of FIG. 2-3, the separation / contact mechanism 50 raises the W image forming unit 10W in the upward direction of the arrow to separate it from the transfer belt 21. At this time, since the W image forming unit 10W has no relation to the printing operation, the W image forming is performed under the control of the development voltage control unit 69, the supply voltage control unit 70, the charging voltage control unit 72, and the layer formation voltage control unit 71. No voltage is applied to the developing roller 13, the supply roller 14, the charging roller 12, and the layer forming blade 15 in the section 10W.

  In step S14, when the print control unit 62 receives a print instruction from the upper level apparatus 101 via the interface unit 61, the C, Y, M image forming units 10C, 10Y, and 10M perform color (C, Y, M) toner. Control is performed to transfer the image 47FC to the colored plain paper 3a.

  That is, since the print control unit 62 causes the CPU 67 to read the motor table 65d from the ROM 65 and prints the colored plain paper 3a, the motor control unit 75 drives the drive motor 75a to drive the drive roller 22 to a predetermined level. Rotate at speed. For example, the transfer belt 21 is operated at 130 mm / s by the driving roller 22 at a printing speed of 30 PPM. Further, the print controller 62 drives the photosensitive drum motor 74a by the motor controller 74 to rotate the photosensitive drums 11C, 11Y, and 11M, and the developing rollers 13 and the supply rollers 14 by motors (not shown). Rotate. When each photoconductor drum 11C, 11Y, 11M rotates, each charging roller 12 rotates with each photoconductor drum 11C, 11Y, 11M and charges the surface of each photoconductor drum 11C, 11Y, 11M.

  When the surfaces of the photosensitive drums 11C, 11Y, and 11M are charged, the LED heads 18C, 18Y, and 18M are imaged on the charged photosensitive drums 11C, 11Y, and 11M under the control of the exposure control unit 73. An electrostatic latent image based on the data is formed. When the electrostatic latent images are formed on the surfaces of the photosensitive drums 11C, 11Y, and 11M, the color toners 17C, 17Y, and 17M held by the supply rollers 14 are supplied to the surfaces of the development rollers 13. When the color toners 17 </ b> C, 17 </ b> Y, and 17 </ b> M on the surface of each developing roller 13 pass through each layer forming blade 15, the layer thickness is regulated and becomes uniform by the shearing force of each layer forming blade 15. When the surfaces of the developing rollers 13 to which the color toners 17C, 17Y, and 17M, which are uniformly regulated, are attached to the surfaces of the photosensitive drums 11C, 11Y, and 11M, the photosensitive drums 11C, 11Y, and 11M are contacted. The color toner images 47C, 47Y and 47M are developed on the electrostatic latent image.

  On the other hand, when the drive motor 75a is driven and the drive roller 22 is rotated under the control of the motor control unit 75, the driven roller 23 is rotated and the transfer belt 21 is rotated. Then, the colored plain paper 3 a which is the printing medium 3 in the paper cassette 2 is fed in the transport direction y by the paper feed roller 4, and then sandwiched by the transport roller unit 5 and controlled by the position sensor control unit 79. The position detection sensor 6 detects the leading position of the colored plain paper 3a. Thereafter, the colored plain paper 3 a is sandwiched between the suction roller 7 and the driving roller 22, and is attracted to the transfer belt 21, and is conveyed through the image forming area PF by the transfer belt 21. The color toner images 47C, 47Y, 47M on the surfaces of the photosensitive drums 11C, 11Y, 11W are transferred to the transfer paper 3b by the transfer rollers 24C, 24Y, 24M to which a high voltage is applied from the power supply unit 100, respectively. Proceed to step S15.

  In step S <b> 15, the heating roller 31 in the fixing unit 30 is heated to a temperature (for example, 160 ° C.) set by the temperature table 65 e in the ROM 65 under the control of the heating roller control unit 77. Therefore, the colored plain paper 3a to which the color toner image 47FC is transferred is sandwiched and conveyed between the heated heating roller 31 and the pressure roller 32 disposed to face the heated roller 31. The color toner image 47FC on the colored plain paper 3a is heated and pressed by the heating roller 31 and the pressure roller 32, and the color toner image 47FC is fixed to the colored plain paper 3a for the second time. Is called. Thereafter, in step S16, the colored plain paper 3a subjected to the fixing process is discharged from the discharge port by the discharge roller unit 34 and conveyed to the discharge cassette 35, and the printing operation on the colored plain paper 3a is completed.

  As described above, in the first embodiment, the user does not replace the W image forming unit 10 </ b> W as compared with the related art, and therefore, as shown in FIGS. 6A and 6B, the W toner image 47W can be printed on or under the color toner image 47FC. In addition, since the W toner image 47W can be printed on both the colored plain paper 3a and the transfer paper 3b, before printing the expensive transfer paper 3b, it is printed on the same color plain paper 3a. Because it can be confirmed, it will not fail, leading to cost reduction.

(Effect of Example 1)
According to the first embodiment, there are the following effects (a) and (b).

  (A) The user can print on both the colored plain paper 3a and the transfer paper 3b without exchanging the plurality of image forming units 10C, 10Y, 10M, and 10W, and can work efficiently.

  For example, a transfer paper for transferring a toner image onto a T-shirt (which is also called a T-shirt transfer paper, an iron transfer paper, or an iron print paper) is known. In a conventional image forming apparatus, when a toner image is transferred to a T-shirt using a transfer paper, a W toner image is printed on the transfer paper as a background of the toner image at the end. It is necessary to arrange the transfer paper at the most downstream in the conveyance direction. However, in the image forming apparatus 1 according to the first exemplary embodiment, it is possible to print on the transfer paper without replacing the image forming units 10C, 10Y, 10M, and 10W, and work efficiently.

  (B) Since the plurality of image forming units 10C, 10Y, 10M, and 10W are selectively separated from and connected to the transfer belt 21, there is no unnecessary idle rotation or unnecessary transfer process, and therefore the plurality of image forming units 10C, 10Y, An image similar to that obtained when 10M and 10W are replaced can be obtained, and the life can be extended.

(Configuration of Example 2)
FIG. 8 is a schematic configuration diagram showing a plurality of image forming units and transfer units which are the main parts of the image forming apparatus according to the second embodiment of the present invention, and shows the image forming apparatus 1 according to the first embodiment in FIG. Elements common to elements are denoted by common reference numerals.

  In the image forming apparatus 1 according to the first embodiment, the arrangement state of the four color image forming units 10 (= 10C, 10Y, 10M, and 10W) is changed from the upstream side toward the downstream side in the print medium conveyance direction. 10C, Y image forming unit 10Y, M image forming unit 10M, and W image forming unit 10W. Instead of such an arrangement state, in the image forming apparatus 1A of the second embodiment, the W image forming unit 10W is arranged on the most upstream side in the medium conveyance direction, and the Y image forming unit 10Y and the M image are arranged on the downstream side. A forming unit 10M and a C image forming unit 10C are arranged.

  Correspondingly, in the case where the print medium 3 is colored plain paper 3a, the image forming units 10W, 10Y, 10M, and 10C are printed without being separated from the transfer unit 20 and transferred to the ROM 65 in FIG. In the case of the paper 3b, a printing operation program 65a-1 for performing printing while separating the image forming units 10W, 10Y, 10M, and 10C from the transfer unit 20 is stored. Other configurations are the same as those of the first embodiment.

(Operation of Example 2)
FIG. 9 is a flowchart showing a printing operation in the image forming apparatus 1A of FIG.

  Since the printing operation of the second embodiment is different from the printing operation of the first embodiment only in the printing order of the four colors W, Y, M, and C, the operation procedure of the flowchart of FIG. Will be explained.

  In the flowchart of FIG. 9, when the printing operation is started and the image forming apparatus 1A is turned on in step S21, the CPU 67 in FIG. 3 reads the printing operation program 65a-1 in the ROM 65 and reads this program. A control signal according to 65a-1 is given to the print control unit 62. The print control unit 62 controls the entire image forming apparatus 1A based on a control signal supplied from the CPU 67, and executes the processes of steps S22 to S36 in the flowchart of FIG.

  In step S <b> 22, the separation / contact control unit 78 controlled by the print control unit 62 in FIG. 3 controls the operation of the separation / contact mechanism 50 to transfer all the image forming units 10 </ b> W, 10 </ b> Y, 10 </ b> M, and 10 </ b> C to the transfer belt 21. The contact is made, and the process proceeds to step S23. In step S23, the user is presented with the print mode setting screen 65b of FIG. 4 to prompt the user to input the print mode MD. When the user selects either colored plain paper 3a or transfer paper 3b as the print medium 3, the print medium 3 is “transfer paper” based on the print medium / print mode correspondence table 65c in FIG. MD is “print W toner image on color toner image” or print medium 3 is “colored plain paper” and print mode MD is “print W toner image under color toner image” Is entered, and the process proceeds to step S24.

  In step S24, the print control unit 62 in FIG. 3 converts the W toner image 47W into color (Y, M, C) toner based on the input information, as shown in FIGS. It is determined whether or not to transfer onto the image 47FC. If the information input by the user is printing on the transfer paper 3b (YES), the print control unit 62 proceeds to step S25, and the information input by the user is printing on the colored plain paper 3a. (NO), the process proceeds to step S34.

  When the process proceeds to step S25, the separation / contact mechanism 50 is operated by the control of the separation / contact control unit 78 in FIG. 3, the W image forming unit 10W is separated from the transfer belt 21, and the process proceeds to step S26. In step S 26, the Y, M, and C image forming units 10 Y, 10 M, and 10 C are operated by the control of the print control unit 62 in FIG. 3, and the color (Y, M, C) toner image 47 FC is printed on the print medium 3. The image is transferred onto a certain transfer paper 3b, and the process proceeds to step S27. In step S27, the fixing unit 30 in FIG. 1 fixes the color toner image 47FC transferred onto the transfer paper 3b for the first time, and the process proceeds to step S28.

  In step S28, the fixed transfer sheet 3b is distributed to the refeed unit 40 by the separator 33 in FIG. The sorted transfer paper 3b loops to the transport roller unit 5 via the transport roller pair 41 and the refeed path 42 in the refeed unit 40, and proceeds to step S29. In step S29, the separation / contact mechanism 50 operates under the control of the separation / contact control unit 78, and the W image forming unit 10W comes into contact with the transfer belt 21, and in step S30, the separation / contact control unit 78 controls. The mechanism 50 operates to move the Y, M, and C image forming units 10Y, 10M, and 10C away from the transfer belt 21, and the process proceeds to step S31.

  In step S31, the W image forming unit 10W operates under the control of the print control unit 62 in FIG. 3, and the W toner is placed on the color toner image 47FC on the transfer paper 3b as shown in FIG. 6B. The image 47W is transferred and the process proceeds to step S32. In step S32, the fixing unit 30 in FIG. 1 fixes the W toner image 47W transferred onto the color toner image 47FC of the transfer paper 3b for the second time, and the process proceeds to step S33. In step S33, the transfer sheet 3b that has been transferred is discharged to the discharge cassette 35 via the discharge roller unit 34 in FIG. 1, and the printing operation on the transfer sheet 3b is completed.

  In step S24, as shown in FIG. 6A, if it is determined to print on colored plain paper 3a (NO), the process proceeds to step S34. In step S34, under the control of the print control unit 62 in FIG. 3, the W image forming unit 10W operates to transfer the W toner image to the colored plain paper 3a, and the process proceeds to step S35. In step S35, the Y, M, and C image forming units 10Y, 10M, and 10C are operated under the control of the print control unit 62 in FIG. 3, and color (Y, M, C) toner is applied on the W toner image 47W. The image 47FC is transferred, and the process proceeds to step 36.

  In step S36, the fixing unit 30 in FIG. 1 fixes the W toner image 47W and the color toner image 47FC transferred onto the colored plain paper 3a for the first time, and the process proceeds to step S33. In step S33, the colored plain paper 3a that has been transferred is discharged to the discharge cassette 35 via the discharge roller unit 34 in FIG. 1, and printing on the colored plain paper 3a is completed.

(Modifications 1 to 5 in FIG. 8)
10, 11, 12, 13, and 14 are modified examples 1, 2, 3, 4, and 5 of FIG. It is a schematic block diagram which shows a unit, and the same code | symbol is attached | subjected to the element common to the element in FIG.

  In Modification 1 shown in FIG. 10, a K image forming unit 10K as a first image forming unit is added to the four color image forming units 10W, 10Y, 10M, and 10C shown in FIG. In these five-color image forming units 10 (= 10K, 10Y, 10M, 10C, 10W), the K image forming unit 10K is arranged at the most upstream from the upstream side to the downstream side in the print medium conveyance direction, and further The Y image forming unit 10Y, the M image forming unit 10M, the C image forming unit 10C, and the W image forming unit 10W are sequentially arranged on the downstream side.

  In the second modification shown in FIG. 11, instead of the W image forming unit 10 </ b> W in FIG. 8, T serving as a second image forming unit that forms a transparent (hereinafter referred to as “T”) toner image for adjusting glossiness. An image forming unit 10T is provided. The four-color image forming units 10 (= 10T, 10Y, 10M, and 10C) are arranged such that the C image forming unit 10C, the Y image forming unit 10Y, and the M image forming unit from the upstream side to the downstream side in the print medium conveyance direction. 10M are arranged in order, and the T image forming unit 10T is arranged on the most downstream side.

  12 has the four color image forming units 10 (= 10T, 10Y, 10M, and 10C) as in FIG. 11, but their arrangement is different from that in FIG. In the third modification, the T image forming unit 10T is disposed on the most upstream side from the upstream side to the downstream side in the print medium conveyance direction, and the Y image forming unit 10Y, the M image forming unit 10M, And the C image forming unit 10C are arranged in order.

  In Modification 4 shown in FIG. 13, a T image forming unit 10T is added to the four color image forming units 10W, 10Y, 10M, and 10C shown in FIG. In these five-color image forming units 10 (= 10W, 10Y, 10M, 10C, and 10T), the T image forming unit 10T is arranged at the most upstream from the upstream side to the downstream side in the print medium conveyance direction, and further The Y image forming unit 10Y, the M image forming unit 10M, the C image forming unit 10C, and the W image forming unit 10W are sequentially arranged on the downstream side.

  14 includes the five color image forming units 10 (= 10 W, 10 Y, 10 M, 10 C, and 10 T) as in FIG. 13, but these arrangement states are different from those in FIG. 13. . In the fourth modification, the W image forming unit 10W, the Y image forming unit 10Y, the M image forming unit 10M, and the C image forming unit 10C are sequentially arranged from the upstream side to the downstream side in the print medium conveyance direction. The T image forming unit 10T is disposed on the most downstream side.

  Even in the arrangement state of the plurality of image forming units 10 shown in the first to fifth modifications, substantially the same operation as that in FIG. 8 can be performed.

  FIG. 15 shows the arrangement of the T image forming unit 10T or the W image forming unit 10W on the most upstream side or the most downstream side in the print medium conveying direction in the image forming apparatuses 1 and 1A of the first and second embodiments and the first to fifth modifications. FIG. 6 is a diagram showing a list of the relationship between the separation from the transfer belt 21 and the transfer at the time of transfer.

  In FIG. 15, an up arrow ↑ indicates separation from the transfer belt 21, and a down arrow ↓ indicates contact with the transfer belt 21.

  For example, in the second embodiment, when the W toner image 47W is printed under the color (Y, M, C) toner image 47FC, the W image forming unit 10W, the Y image forming unit 10Y, the M image forming unit 10M, and C The image forming unit 10C is brought into contact with the transfer belt 21, and the respective colors W, Y, M, and C are transferred at once, and the fixing is completed once. When the W toner image 47W is printed on the color toner image 47FC, the W image forming unit 10W is separated from the transfer belt 21, and the Y, M, and C image forming units 10Y, 10M, and 10C are in contact with the transfer belt 21. Then, only the color toner image 47FC is transferred and fixed to the print medium 3, and after the fixed print medium 3 is looped, this time, the W image forming unit 10W is brought into contact with the transfer belt 21, and the Y, M, C image is obtained. The forming units 10Y, 10M, and 10C are separated from the transfer belt 21, and only the W toner image 47W is transferred and fixed to print the W toner image 47W on the color toner image 47FC.

(Effects of Example 2 and Modifications 1 to 5)
According to the second embodiment and the first to fifth modifications, there are substantially the same effects as the first embodiment.

(Configuration of Example 3)
FIG. 16 is a diagram showing an example of the print mode setting screen 65B in the image forming apparatus according to the third embodiment of the present invention. Elements common to the elements in FIG. 4 showing the print mode setting screen 65b according to the first embodiment are shown in FIG. The common code | symbol is attached | subjected.

  In the print mode setting screen 65B in the image forming apparatus 1B of the third embodiment, a button 65b-4 for increasing the density of the W color is added to the print mode setting screen 65b of the first embodiment. This print mode setting screen 65B is stored in the ROM 65 in FIG. 3 instead of the print mode setting screen 65b of the first embodiment. Further, a program 65 a-2 for a printing operation different from that in the first embodiment is stored in the ROM 65. Other configurations of the image forming apparatus 1B are the same as those in FIGS.

(Operation of Example 3)
FIG. 17 is a flowchart illustrating a printing operation in the image forming apparatus 1B according to the third embodiment.

  In the flowchart of FIG. 17, when the printing operation is started and the image forming apparatus 1B is turned on in step S41, the CPU 67 in FIG. 3 reads the program 65a-2 for the printing operation in the ROM 65 and reads this program. A control signal according to 65a-2 is given to the print control unit 62. The print control unit 62 controls the entire image forming apparatus 1B based on a control signal given from the CPU 67, and executes the processes of steps S42 to S76 in the flowchart of FIG.

  In step S42, the separation control unit 78 controlled by the print control unit 62 in FIG. 3 brings the C, Y, M, W image forming units 10C, 10Y, 10M, 10W into contact with the transfer belt 21, and step S43. Proceed to In step S43, the user operates the host device 101 in FIG. 3, calls the print mode setting screen 65B in FIG. 16 from the ROM 65 via the interface 61 and the print control unit 62, and via the CPU 67. 101 is displayed on the display unit 101. The host apparatus 101 prompts the user to input the print mode MD. The user operates the print mode setting screen 65B displayed on the display unit of the host apparatus 101 to select, for example, the transfer sheet 3b from the print medium list 65b-1 and increase the W color density button 65b- 4 is checked and the OK button 65b-2 is pressed, this input information is sent to the print controller 62 via the interface 61, and the process proceeds to step S44.

  In step S44, the print control unit 62 determines whether or not to increase the density of the W toner image 47W, and the button 65b-4 for increasing the density of W color is checked on the print mode setting screen 65B. Since it is entered (YES), the process proceeds to step S45. If the button 65b-4 for increasing the density of W color is not checked on the print mode setting screen 65B (NO), the process proceeds to step S63.

  In step S45, the print controller 62 calls the print medium / print mode correspondence table 65c of FIG. 5 from the ROM 65 via the CPU 67, and puts the W toner image 47W on the color (C, Y, M) toner image 47FC. It is determined whether or not to transfer. Since the transfer sheet 3b is selected as described above, the print mode MD becomes “print W toner image on the color toner image” (YES), and the process proceeds to step S46. When the colored plain paper 3a is selected (NO), the process proceeds to steps S52, S53, and S54 added to the first embodiment.

  In step S46, the print control unit 62 controls the C, Y, M image forming units 10C, 10Y, and 10M in FIG. 1, and as shown in FIG. , Y, M) The toner image 47FC is transferred, and the process proceeds to step S47. In step S47, the print control unit 62 controls the W image forming unit 10W in FIG. 1 to transfer the W toner image 47W onto the color toner image 47FC, and the process proceeds to step S48. In step S48, the print control unit 62 controls the fixing unit 30 to perform the first fixing on the color toner image 47FC and the W toner image 47W transferred onto the transfer paper 3b. The process proceeds to the added steps S49, S50, and S51.

  In step S49, the transfer sheet 3b that has been fixed for the first time is distributed to the refeed unit 40 by the separator 33 in FIG. 1, loops to the transport roller unit 5, and proceeds to step S50. In step S50, the separation / contact control unit 78 in FIG. 3 controls the operation of the separation / contact mechanism 50 to separate the C, Y, M image forming units 10C, 10Y, 10M from the transfer belt 21. Then, the print control unit 62 controls the W image forming unit 10W to transfer the W toner image 47W again onto the fixed W toner image 47W on the transfer paper 3b, so that the W toner image 47W is transferred. Processing for increasing the density is performed, and the process proceeds to step S51. In step S51, the print control unit 62 controls the fixing unit 30 to perform the second fixing on the W toner image 47W transferred again onto the transfer paper 3b, and proceeds to the discharge process in step S63.

  If the colored plain paper 3a is selected in step S45 (NO), the process proceeds to steps S52, S53, and S54 added to the first embodiment. In step S52, the separation / contact control section 78 in FIG. 3 controls the operation of the image forming apparatus 1B to separate the C, Y, M image forming sections 10C, 10Y, 10M from the transfer belt 21. Then, the print control unit 62 controls the W image forming unit 10W to transfer the W toner image 47W onto the colored plain paper 3a as shown in FIG. 6A, and proceeds to step S53. In step S53, the printing control unit 62 controls the fixing unit 30 in FIG. 1 to perform the first fixing on the W toner image 47W transferred onto the colored plain paper 3a, as in the first embodiment. The process proceeds to steps S55 to S62.

  In step S55, the colored plain paper 3a that has been fixed for the first time is distributed to the refeed unit 40 by the separator 33 in FIG. 1, loops to the transport roller unit 5, and proceeds to step S56. In step S56, the W image forming unit 10W performs a process of transferring the W toner image 47W again onto the fixed W toner image 47W on the colored plain paper 3a and increasing the density of the W toner image 47W. Then, go to step S57. In step S57, the fixing unit 30 in FIG. 1 performs the second fixing on the W toner image 47W transferred again onto the colored plain paper 3a, and proceeds to step S58. In step S58, the second fixed colored plain paper 3a is looped to the transport roller unit 5 by the separator 33 and the refeed unit 40, and proceeds to step S59.

  In step S59, the C / Y / M image forming units 10C, 10Y, and 10M are brought into contact with the transfer belt 21 by the separation / contact mechanism 50. And go to step S61. In step S61, as shown in FIG. 6A, the color (C) is formed on the fixed W toner image 47W on the colored plain paper 3a by the C, Y, M image forming units 10C, 10Y, 10M. , Y, M) The toner image 47FC is transferred, and in step S62, the fixing unit 30 performs the third fixing, and the process proceeds to the discharging process in step S63.

  In step S44, when the density of the W toner image 47W is not increased (NO), the same processes of steps S64 to S76 as the processes of steps S4 to S15 of FIG.

(Effect of Example 3)
The third embodiment has the following effects (1) and (2).

  (1) FIG. 18 is a diagram illustrating experimental results of Examples 1 and 2 and Modifications 1 to 5 and Example 3.

  In FIG. 18, the horizontal axis represents the number of transfers, and the vertical axis represents the lightness L *. Reference numeral 110 represents the experimental results of Examples 1 and 2 and Modifications 1 to 5 in which the number of times of transfer was one, and reference numeral 111 represents the experimental result of Example 3 in which the number of times of transfer was two. The density value of the lightness L * is measured using an X-Rite 530 spectral densitometer, and the target density value here is a solid image density with an area ratio of 100%.

  In the third embodiment, unlike the first embodiment, when the button 65b-4 for increasing the density of the W color is checked on the print mode setting screen 65B in FIG. 16, when the print medium 3 is the transfer paper 3b, In the case of colored plain paper 3a in steps S49 to S51 in FIG. 17, processing for transferring and fixing the W toner image 47W is added to steps S52 to S54 in FIG. Therefore, when the number of times of transfer and fixing of the W toner image 47W is increased from once in the first and second embodiments and the first to fifth modifications to twice in the third embodiment, the value of the lightness L * is 2 and 75, which is the experimental result 110 of the first to fifth modified examples, to 85, which is the experimental result 111 of the third embodiment.

  (2) As described in (1) above, in Example 3, since the W toner image 47W is printed twice, the density becomes high, and it is not affected by the lining, and the image quality can be improved. .

(Examples 1, 2 and 1 to 5 and other modifications of Example 3)
The present invention is not limited to the above-described embodiments and modifications, and other forms of use and modifications are possible. For example, the following forms (a) and (b) are used as the usage form and the modified examples.

  (A) The image forming apparatus 1 in FIG. 1, the separation / contact mechanism 50 in FIGS. 2-1 to 2-3, and the block in FIG. 3 may be changed to configurations other than those illustrated. For example, in the image forming apparatus 1 shown in FIG. 3, the motor table 65d and the temperature table 65e in the ROM 65 may be provided at other locations. The CPU 67 may be provided in the print control unit 62 to simplify the circuit configuration.

  (B) In Embodiments 1 to 3 and Modifications 1 to 5 described above, the tandem type image forming apparatuses 1, 1 </ b> A, and 1 </ b> B have been described. The present invention can also be applied to a four-cycle type image forming apparatus or an intermediate transfer belt type image forming apparatus. The present invention can also be applied to a multifunction peripheral (MFP) other than a printer, a facsimile machine, and a copying machine.

1, 1A, 1B Image forming apparatus 3 Print medium 3a Plain paper 3b Transfer paper 10, 10C, 10Y, 10M, 10K, 10W, 10T Image forming unit 11, 11C, 11Y, 11M, 11K, 11W, 11T Photosensitive drum 12 Charging roller 13 Developing roller 14 Supply roller 15 Layer forming blade 16 Toner tank 17, 17C, 17Y, 17M, 17W Toner 18, 18C, 18Y, 18M, 18W LED head 20 Transfer unit 21 Transfer belt 24, 24C, 24Y, 24M, 24W Transfer roller 30 Fixing unit 31 Heating roller 32 Pressure roller 33 Separator 40 Refeed unit 50 Separation / contact mechanism 62 Print controller 65 ROM
65a, 65a-1, 65a-2 Print operation program 65b, 65B Print mode setting screen 65c Print medium / print mode correspondence table 67 CPU

Claims (14)

A first image forming unit disposed in the image forming region and generating a color developer image; and a second image forming unit configured to form a spot color developer image having a color different from the color developer image. An image forming unit, and the color developer image formed by the first image forming unit and the second image forming unit, which is disposed opposite to the first image forming unit and the second image forming unit. a transfer unit for transferring onto a print medium and the spot color developer image, and a fixing unit for fixing the color developer image and the spot color developer image transferred onto the printing medium by the transfer unit, the According to a printing mode for selecting the order of stacking the color developer image and the spot color developer image set according to the type of print medium, the first image forming unit, the second image forming unit, and the Select the transfer section Depending on to the disjunction means in contact away, the printing mode, and a subscriber loop carrier unit capable of multiple loops conveying the print medium in the image forming region, the type of the print medium include plain paper and A transfer paper, and the special color developer image includes a white developer image. When the plain paper is used, the white developer image is formed under the color developer image, and the transfer paper In the case of using the image forming apparatus , the white developer image is formed on the color developer image . The spot color developer image includes a transparent developer image, When the plain paper is used, the transparent developer image is formed on the color developer image. When the transfer paper is used, the transparent developer image is formed below the color developer image. To The image forming apparatus according to claim 1, wherein the image forming apparatus is configured. The image forming apparatus according to claim 1, further comprising a print control unit. The print control means includes Based on the print medium / print mode correspondence information indicating the correspondence between the print medium and the print mode, the spot color developer image is applied to the print medium according to the selected print mode. An image forming apparatus that performs control to selectively form on either the upper side or the lower side. The first image forming unit and the second image forming unit are separately contacted and separated from the transfer unit by the separation / contact unit according to the printing mode, and form an image. Item 4. The image forming apparatus according to any one of Items 1 to 3. The said separating / contacting unit separates the first image forming unit from the transfer unit and contacts the second image forming unit with the transfer unit according to the printing mode. 5. The image forming apparatus according to any one of 4 above. The first image forming unit and the second image forming unit are arranged in the image forming region at a predetermined interval with respect to a conveyance direction of the print medium, The image forming apparatus according to claim 1, wherein the second image forming unit is disposed on the most upstream side or the most downstream side with respect to the transport direction. A first image forming unit disposed in the image forming region and generating a color developer image; A second image forming unit disposed in the image forming region and forming a spot color developer image having a color different from that of the color developer image; The color developer image formed by the first image forming unit and the special color developer formed by the second image forming unit, disposed opposite to the first image forming unit and the second image forming unit. A transfer part for transferring the agent image onto the print medium; A fixing unit for fixing the color developer image and the spot color developer image transferred onto the print medium by the transfer unit; the color developer image and the spot color developer image set according to the type of the print medium; According to a printing mode for selecting the order of lamination with the first image forming unit, the second image forming unit and the transfer unit that selectively contacts and separates the transfer unit; Loop conveying means capable of loop conveying the print medium a plurality of times in the image forming area according to the printing mode, The types of print media include plain paper and transfer paper, The spot color developer image includes a white developer image, When using the plain paper, the white developer image is formed under the color developer image, When using the transfer paper, the white developer image is formed on the color developer image, An image forming apparatus, An image forming apparatus having another printing mode for increasing the density of the white developer image. Each image forming unit in the first image forming unit and the second image forming unit is: An electrostatic latent image carrier that carries an image as an electrostatic latent image; Charging means for charging the electrostatic latent image carrier; A developer carrier for developing the electrostatic latent image formed on the electrostatic latent image carrier; Developer supply means for supplying a developer to the developer carrier; Layer forming means for making the developer on the developer carrier a uniform layer; Developer storage means for storing the developer and supplying the developer to the developer supply means, Exposure means for exposing the electrostatic latent image carrier to form the electrostatic latent image on the electrostatic latent image carrier is provided in the vicinity of each image forming unit. The image forming apparatus according to claim 1. The electrostatic latent image carrier is a photosensitive drum, The charging means includes a charging roller, The developer carrier includes a developing roller, The developer supply means includes a supply roller, The layer forming means includes a layer forming blade, The developer storage means includes a removable developer tank, The image forming apparatus according to claim 8, wherein the image forming apparatus is an image forming apparatus. The transfer portion is A transfer belt for conveying the print medium to the image forming area; Transfer means for contacting the electrostatic latent image carrier via the transfer belt; The image forming apparatus according to claim 1, wherein the image forming apparatus includes: The electrostatic latent image carrier is a photosensitive drum, The image forming apparatus according to claim 10, wherein the transfer unit is a transfer roller. The fixing unit is 8. A heating roller and a pressure roller for fixing the color developer image and the special color developer image transferred onto the printing medium by heating and pressing, respectively. The image forming apparatus described in 1. The separation means is A configuration in which the first image forming unit and the second image forming unit are collectively moved up and down with respect to the fixed transfer unit; A structure in which the first image forming unit and the second image forming unit are fixed and the transfer unit is moved up and down; Alternatively, a configuration in which the first image forming unit and the second image forming unit are individually moved up and down with respect to the fixed transfer unit, The image forming apparatus according to claim 1, wherein the image forming apparatus is any one of the separation / contact mechanisms. The loop conveying means is 8. The re-feeding unit that transports the print medium that has been fixed and switched by the fixing unit to the image forming area without changing a printing surface of the print medium. The image forming apparatus according to claim 1.

Images