JP2003323025A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of changing an apparatus for forming a monochrome image purchased at the start to an apparatus for forming a color image without wasting the apparatus for forming the monochrome image. <P>SOLUTION: The image forming apparatus has an apparatus main body 10 equipped with a fixing part 40 for fixing a toner image on paper on which the toner image is formed by a monochrome image forming part 30 for forming a monochrome toner image on the paper fed by a paper feeding part 20 feeding the paper, and the color image forming unit 60 capable of forming the color toner image on the paper is constituted to be attached to/detached from the main body 10 between the paper feeding part 20 and the fixing part 40. The paper feeding part 20 and the fixing part 40 can be separated up and down by dividing the housings 11 and 12 of the apparatus main body up and down, and the unit 60 is attached in a laminated state between both of them. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a facsimile or a copying machine, which forms an image on a sheet by using an electrophotographic technique.

2. Description of the Related Art Generally, an image forming apparatus using an electrophotographic technique supplies a sheet (in this specification, a sheet-shaped recording medium such as a postcard, an envelope, a sheet for an OHP, etc. is simply referred to as "sheet"). A paper feeding unit for feeding, an image forming unit for forming a toner image on the paper fed by the paper feeding unit, and a fixing unit for fixing the toner image on the paper on which the toner image is formed by the image forming unit. Is equipped with.

[0002]

Conventionally, as image forming apparatuses, a monochrome image forming apparatus and a color image forming apparatus are separately manufactured and sold. In comparison, a color image forming device is more expensive. For this reason, even if the user wants a device for color image formation, there is a situation where the user has to put up with the purchase of a device for monochrome image formation for the time being, but then purchases a device for color image formation. In this case, there is a problem that the monochrome image forming apparatus that was initially purchased must be discarded even though it is still usable due to restrictions such as installation location.

An object of the present invention is to solve the above-mentioned problems and to replace the originally purchased device for forming a monochrome image with a device for forming a color image without wasting the device. An object of the present invention is to provide an image forming apparatus capable of performing the above.

[0004]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention is a sheet feeding unit for feeding a sheet, and a monochrome toner on the sheet fed by the sheet feeding unit. An image forming apparatus having an apparatus main body, comprising: a monochrome image forming section for forming an image; and a fixing section for fixing the toner image on a sheet on which a toner image is formed by the monochrome image forming section, the image forming apparatus comprising: On the other hand, a color image forming unit capable of forming a color toner image is configured to be attachable to and detachable from the apparatus body between the paper feeding unit and the fixing unit. The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1,
The paper feeding unit and the fixing unit can be separated into upper and lower parts by vertically dividing the casing of the main body of the apparatus, and the color image forming unit is detachably mounted in a laminated state between them. It is characterized by According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the color image forming unit is also provided with a monochrome image forming section. The image forming apparatus according to claim 4 is the image forming apparatus according to claim 3, wherein the black toner in the monochrome image forming portion of the apparatus main body has a lower glossiness than the black toner in the color image forming unit. It is characterized by

[0005]

According to the image forming apparatus of the present invention, the sheet feeding section for feeding the sheet, the monochrome image forming section for forming a monochrome toner image on the sheet fed by the sheet feeding section, and the monochrome image forming section. An image forming apparatus having an apparatus main body having a fixing unit for fixing a toner image on a sheet on which a toner image is formed by the image forming unit, the color image being capable of forming a color toner image on the sheet. The forming unit
The image forming apparatus according to the first aspect of the present invention has the following effects because it is configured so as to be attachable to and detachable from the apparatus body between the paper feeding unit and the fixing unit. That is, the user purchases only the main body of the apparatus for the time being as an apparatus for forming a monochrome image, then purchases a color image forming unit as necessary, and attaches the color image forming unit to the main body of the apparatus so that the apparatus is colored. It can be changed to one for image formation. Therefore, this device can be changed to a device for color image formation without wasting the device (device body) for monochromatic image that was initially purchased. In addition, it is possible to change the own device to a device for color image formation by purchasing a color image forming unit without purchasing a device that is manufactured and sold as a color image forming device from the beginning, which is inexpensive. Therefore, a color image forming apparatus can be obtained. As described above, according to the image forming apparatus of the first aspect, the apparatus for color image formation is changed without wasting the apparatus for monochrome image formation that was initially purchased. You can, and
A color image forming apparatus can be obtained at low cost. According to the image forming apparatus of claim 2, in the image forming apparatus of claim 1, the paper feeding section and the fixing section are:
The color image forming unit can be separated into upper and lower parts by dividing the casing of the device main body into upper and lower parts, and the color image forming unit is detachably mounted between them in a laminated manner. It can be easily attached and detached. Moreover, the problem that the installation area is increased by mounting the color image forming unit on the apparatus main body does not occur. According to the image forming apparatus of claim 3, in the image forming apparatus of claim 1 or 2,
Since the monochrome image forming unit is also provided for the color image forming unit, when forming a color image including black, good color matching is achieved between the black image and images of other colors. Will be done. According to the image forming apparatus of claim 4, in the image forming apparatus of claim 3, the black toner in the monochrome image forming portion of the apparatus body is more glossy than the black toner in the color image forming unit. Is lower, a more appropriate black image can be obtained. For example, for image images such as photographs, a glossy image is obtained with black toner in the color image forming unit, and for character information and the like, black toner in the monochrome image forming unit of the apparatus main body obtains easily readable characters with low gloss Will be able to.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a schematic side view showing a first embodiment of an image forming apparatus according to the present invention, (a) showing only the apparatus main body, and (b) showing the apparatus main body. FIG. 6 is a diagram showing a state in which a color image forming unit is mounted. As shown in FIG. 1A, the apparatus main body 10 includes a sheet feeding unit 20 that feeds a sheet (not shown), and a monochrome unit that forms a monochrome toner image on the sheet fed by the sheet feeding unit 20. An image forming unit 30 and a fixing unit 40 for fixing the toner image on the sheet on which the toner image is formed by the monochrome image forming unit 30.
It has and.

The body of the apparatus 10 is divided into a lower case 11 and an upper case 12, the lower case 11 is provided with the paper feed section 20, and the upper case 12 is provided with the monochrome unit. An image forming unit 30 and a fixing unit 40 are provided.

In the lower case 11 and the upper case 12, a paper path 50 is formed so as to extend over both cases. The paper path 50 is formed in a closed loop shape including a paper transport path 51 and a return path 52. The sheet conveying path 51 includes a pair of conveying rollers 51a, a pair of gate rollers 51b that controls the timing of sheet supply to a transfer unit described later, a photoconductor 31 and a transfer roller 34 described later, and a heating roller pair that forms a fixing unit 40. 41 and a paper discharge roller pair 51c. The return path 52 is formed by the paper discharge roller pair 51c, the first return roller pair 52a, the second return roller pair 52b, and the U-shaped transfer path 51u.

The paper feed section 20 includes a paper feed cassette 21 for accommodating a plurality of sheets of paper in a stacked form, and a paper feed roller 22 for feeding the papers from the paper feed cassette 21 one by one to the paper feed path 51. Is equipped with.

The monochrome image forming section 30 has a monochrome photoreceptor 31 having a photosensitive layer on its outer peripheral surface, a charging means (not shown) for uniformly charging the outer peripheral surface of the photoreceptor 31, and a uniform charging means by this charging means. An exposing unit 32 that selectively exposes the charged outer peripheral surface to form an electrostatic latent image, and a toner that is a developer is applied to the electrostatic latent image formed by the exposing unit 32 to make it visible. Developing means 33 for forming an image (toner image)
And a transfer unit 34 for transferring the toner image developed by the developing unit 33 onto a sheet to be transferred. The exposure means 32 is composed of an exposure unit. The developing means 33 is a case 33a containing black toner.
And a developing roller 33b for applying the black toner contained in the case 33a to the photoconductor 31. The transfer means 34 is
It is composed of a transfer roller which is arranged so as to face the photoconductor 31 with the sheet conveyance path 51 interposed therebetween. The photoconductor 31 and the developing device 33 are configured as one cartridge 34.

A monochrome image on a sheet by the apparatus body 10 as described above is formed as follows. The photosensitive member 31 and other necessary rollers are rotatably driven by a driving unit (not shown) as necessary, and the surface of the photosensitive member 31 is selectively exposed by the exposure unit 32 to form a latent image, and the latent image is developed. After being developed by the roller 33b to form a toner image, it is transferred onto a sheet at the transfer section T, is fixed on the sheet at the fixing section 40, and is discharged onto the upper case 12 by the discharge roller pair 51c. Part (sheet ejection tray part) 1
It is discharged to 2a. However, when images are formed on both sides of the paper, the paper ejection roller pair 51c is reversed before the trailing edge of the paper passes through the paper ejection roller pair 51c, and the paper is supplied to the return path 52 in a switchback manner. , The image is formed on the back side of the sheet again supplied to the transfer section T, and the sheet discharge section 12a
Will be discharged to.

In the image forming apparatus of this embodiment, as described above, the apparatus body 10 has a casing (case) divided into a lower case 11 and an upper case 12, and the inside of the lower case 11 is the above-mentioned case. A paper feeding unit 20 is provided, and the monochrome image forming unit 30 and the fixing unit 40 are provided in the upper case 12. Therefore, as shown in FIG.
0 and the fixing unit 40 can be separated into upper and lower parts by dividing the casing of the apparatus main body 10 into the upper and lower parts, and between them (the sheet feeding unit 20 and the fixing unit 40, and therefore the lower part). The color image forming unit 60 is detachably mounted in a laminated shape between the case 11 and the upper case 12. The lower case 11 and the color image forming unit 60, and the color image forming unit 60 and the upper case 12 are detachably fixed by appropriate means.

The color image forming unit 60 is for forming a color toner image on a sheet, and is a case 61 and a sheet which is incorporated in the case and is fed by the sheet feeding section 20. A color image forming unit 62 for forming a color toner image (in this embodiment, a color toner image of each color toner image of a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image), and the paper transport path 51. Transport extension path 51d for extension
And a return extension path 52c for extending the return path 52
And have. The transfer extension path 51d is provided with a secondary transfer backup roller 66c and a secondary transfer roller 67, which will be described later, and the return extension path 52c includes a third return roller pair 52d and a fourth return roller pair 52e. Is provided.

The color image forming section 62 has photoconductors 63 (Y, M, for each color (yellow (Y), magenta (M), cyan (C), black (K)) having a photosensitive layer on the outer peripheral surface.
C, K) and a charging unit (not shown) for uniformly charging the outer peripheral surface of the photoconductor 63 (Y, M, C, K),
Exposure means 64 (Y, M) for selectively exposing the outer peripheral surface of the photoconductor uniformly charged by the charging means to L (Y, M, C, K) to form an electrostatic latent image for each color. , C,
K) and toners (Y, M, C, K) as respective developers are applied to the electrostatic latent images formed by the exposing means 64 (Y, M, C, K) to make them visible. Developing means 65 (Y, M, C, K) for forming an image (toner image of each color), and toner images of each color developed by the developing means 65 (Y, M, C, K) are respectively transferred to the primary transfer portions T1. And an intermediate transfer body 66 that collectively transfers the toner image, which is primarily transferred and superposed, into a full color image by the secondary transfer unit T2.

Each exposure means 64 (Y, M, C, K) is composed of an exposure unit. Each developing means 65
(Y, M, C, K) is a case 65a containing toner of each color, and a developing roller 65 for applying the toner contained in the case 65a to the photoconductor 63.
and b for each color. The intermediate transfer member 66 includes a driving roller 66a and a driven roller 66b.
And a secondary transfer backup roller 66c, which is an endless intermediate transfer belt. A secondary transfer roller 67 is opposed to the secondary transfer backup roller 66c with the intermediate transfer belt 66 and the paper transport path 51 (transport extension path 51d) interposed therebetween, and a secondary transfer portion T2 is formed by them. There is. It should be noted that each of the photoconductor 63 and the developing device 65 is configured as one cartridge.

As is apparent from the above description, in this embodiment, the monochrome image forming units (63 (K), 64) are also used for the color image forming unit 60.
(K), 65 (K)) are provided. Further, the black toner (developing device 65
(For black toner contained in (K)),
A toner having a higher glossiness than the black toner (black toner contained in the developing device 33) in the monochrome image forming unit 30 of the apparatus body 10 is used. That is, the black toner (developing device 6) in the color image forming unit 60 is
5 (K) stored in 5 (K)),
The black toner (black toner contained in the developing device 33) in the monochrome image forming unit 30 of the apparatus body 10 has lower gloss.

The color image on the sheet by the apparatus body 10 as described above is formed as follows. Each photoconductor 63 and other necessary rollers and the intermediate transfer belt 66 are rotatably driven by a driving unit (not shown), and the surface of each photoconductor 63 is selectively exposed by each exposure unit 64 to form a latent image. Is formed, and the latent image is developed by each developing roller 65 to form a toner image of each color. Then, the primary transfer portion T1 transfers the latent image to the intermediate transfer body 66, and the superimposed image is a full color image. The image is collectively transferred onto the sheet at the next transfer section T2, then fixed on the sheet at the fixing section 40, and is discharged onto the sheet discharge section (sheet discharge tray section) 12a formed on the upper case 12 by the sheet discharge roller pair 51c. Is discharged. However, when images are formed on both sides of the paper, the trailing edge of the paper is the pair of paper ejection rollers 51c.
Before passing through the sheet, the pair of sheet discharge rollers 51c is reversely rotated to supply the sheet in a switchback manner to the return path 52, and is supplied to the secondary transfer portion T2 again to form an image on the back surface of the sheet and the sheet is discharged. It will be discharged to the portion 12a. When forming a color image, the roller pair 51a is configured to function as a gate roller pair.

As is clear from the above, when the paper feeding unit 20 and the fixing unit 40 form a monochrome image (FIG. 1A).
And the case of forming a color image (FIG. (B)) are shared. When forming a color image, it is not always necessary to form an image by the monochrome image forming unit 30, but for the character information and the like, the monochrome image forming unit 30 is used.
To form. By doing so, the black toner having a low glossiness by the monochrome image forming unit 30 causes
You can get easy-to-read characters.

According to the image forming apparatus as described above, the following operational effects can be obtained. (A) This image forming apparatus includes a paper feed unit 20 for feeding paper.
A monochrome image forming section 30 that forms a monochrome toner image on the sheet fed by the sheet feeding section 20, and a fixing that fixes the toner image on the sheet on which the toner image is formed by the monochrome image forming section 30. An image forming apparatus having an apparatus main body 10 including a section 40, wherein a color image forming unit 60 capable of forming a color toner image on a sheet is provided with respect to the apparatus main body 60. 40
Since it is configured so that it can be detached between the user and the user, the user first purchases only the apparatus main body 10 (see FIG. (A)) as an apparatus for forming a monochrome image, and then, if necessary, forms a color image. Buy unit 60,
By mounting this on the apparatus main body 10, this apparatus can be changed to one for color image formation (see FIG. (B)). Therefore, this device can be changed to a device for color image formation without wasting the device (device body) 10 for monochrome image formation that was originally purchased. Moreover, since it is possible to change the own device to a device for forming a color image by purchasing the color image forming unit 60 without purchasing a device manufactured and sold as a color image forming device from the beginning. A color image forming apparatus can be obtained at low cost. As described above, according to this image forming apparatus, this apparatus can be changed to a color image forming apparatus without wasting the initially purchased monochrome image forming apparatus 10. Moreover, the color image forming apparatus can be obtained at low cost. (B) The paper feeding unit 20 and the fixing unit 40 can be separated into upper and lower parts by dividing the casing of the apparatus main body 10 into upper and lower parts (11, 12), and the color image is laminated between them. Since the forming unit 60 is detachably attached, the color image forming unit 60 can be easily attached to and detached from the apparatus main body 10. Moreover, the installation area is not increased by mounting the color image forming unit 60 on the apparatus main body 10. (C) The monochrome image forming unit (63 (K), 64 (K), 65 (K)) is also provided for the color image forming unit 60.
Is provided, it is possible to achieve good color matching between the black image and the images of other colors (Y, M, C) when forming a color image including black. (D) Monochrome image forming unit (63 (K), 64 (K), 65 (K)) unit 30 of the apparatus main body 10 rather than black toner in the color image forming unit 60
The black toner in (1) has a lower glossiness, so that a more appropriate black image can be obtained. For example, for an image image such as a photograph, a glossy image is obtained by the black toner in the color image forming unit 60, and for character information and the like, the glossiness is low and easy to read by the black toner in the monochrome image forming unit 30 of the apparatus body 10. You will be able to get the characters.

<Second Embodiment> FIG. 2 is a schematic side view showing a second embodiment of the image forming apparatus according to the present invention.
FIG. 7A is a diagram showing only the apparatus main body, and FIG. 9B is a diagram showing a state in which a color image forming unit is attached to the apparatus main body. In FIG. 2, the same parts or corresponding parts as those in the first embodiment described above are designated by the same reference numerals. This embodiment is different from the above-described first embodiment in that the exposure unit 32 provided in the apparatus main body 10 is composed of an exposure unit for both a monochrome image and a color image, as shown in FIG. In addition, when the color image forming unit 60 is attached to the apparatus main body 10, the exposure unit 32 causes a latent image to appear between the monochrome photoconductor 31 and the color photoconductor 63 (Y, M, C, K). The point is that the image can be written, and the other points are the same. Also in this embodiment, the operational effects (a) to (d) according to the first embodiment can be obtained. Further, according to this embodiment, the exposure amount of the apparatus main body 10 is slightly higher than that of the first embodiment, because the exposure unit 32 of the apparatus main body 10 is composed of an exposure unit for both a monochrome image and a color image. However, since the color image forming unit 60 can be provided correspondingly at a low cost, the user can change the color image forming apparatus at a lower cost.

<Third Embodiment> FIG. 3 is a schematic side view showing an image forming apparatus according to a third embodiment of the present invention.
FIG. 7A is a diagram showing only the apparatus main body, and FIG. 9B is a diagram showing a state in which a color image forming unit is attached to the apparatus main body. In FIG. 3, the same parts or corresponding parts as those of the first embodiment described above are designated by the same reference numerals. This embodiment differs from the first embodiment described above in that the color image forming unit 60 is not provided with the monochrome image forming portions (63 (K), 64 (K), 65 (K)). (The monochrome image forming unit is removed from the color image forming unit 60), and the other points are the same. Also according to this embodiment, the effects of (a) and (b) according to the first embodiment can be obtained. Also,
According to this embodiment, as compared with the first embodiment, the color image forming unit 60 does not need to be provided with a monochrome image forming unit, and thus the color image forming unit 60 is not provided.
Can be provided at low cost, so that the user can change the color image forming apparatus at a lower cost. Furthermore, according to this embodiment, the height of the color image forming unit 60 can be reduced by the amount that the color image forming unit 60 does not need to be provided with a monochrome image forming section, and as a result, the entire apparatus (see FIG. The height of b)) can be reduced.

<Fourth Embodiment> FIG. 4 is a schematic side view showing an image forming apparatus according to a fourth embodiment of the present invention.
FIG. 7A is a diagram showing only the apparatus main body, and FIG. 9B is a diagram showing a state in which a color image forming unit is attached to the apparatus main body. In FIG. 4, the same or corresponding parts as those of the first embodiment described above are designated by the same reference numerals. This embodiment is different from the above-described first embodiment in that the apparatus body 10 is formed in a substantially L shape in a side view, and the recess 13 forms a mounting portion for the color image forming unit 60. The intermediate transfer member 66 is provided for the unit 10, and the color image forming unit 60 having no monochrome image forming unit can be attached to and detached from the recess 13, and the other points are the same. Also according to this embodiment, the effect (a) according to the first embodiment can be obtained. Further, according to this embodiment,
Compared to the first embodiment, the color image forming unit 60 can be provided at a low cost because the color image forming unit 60 does not need to be provided with a monochrome image forming unit, and therefore the user can install the color image forming apparatus in the color image forming apparatus. The change can be made more inexpensively. Furthermore, according to this embodiment, the color image forming unit 60 is
The height of the color image forming unit 60 can be reduced by the amount that the monochrome image forming unit need not be provided, and as a result, the height of the entire apparatus (see FIG. (B)) can be reduced.

<Fifth Embodiment> FIG. 5 is a schematic side view showing a fifth embodiment of the image forming apparatus according to the present invention.
FIG. 7A is a diagram showing only the apparatus main body, and FIG. 9B is a diagram showing a state in which a color image forming unit is attached to the apparatus main body. In FIG. 5, the same parts or corresponding parts as those in the first embodiment described above are designated by the same reference numerals. This embodiment is different from the above-described first embodiment in that the color image forming section 62 in the color image forming unit 60 is provided with each color (yellow (Y), magenta (M)) having a photosensitive layer on the outer peripheral surface. One photosensitive member 63 for both cyan (C) and black (K), one charging unit (not shown) for uniformly charging the outer peripheral surface of the photosensitive member 63, and the charging unit for uniform charging. One exposure unit 64 for each color, which sequentially forms an electrostatic latent image for each color by exposing L (Y, M, C, K) the outer peripheral surface of the photoconductor for each color.
(Y, M, C, K) and toner (Y, M, C, K) as a developer can be sequentially applied to the electrostatic latent images for the respective colors sequentially formed by the exposure means 64. A rotary developing device 68 as a visual image (each color toner image), and toner images of each color sequentially developed by the rotary developing device 68 are sequentially primary-transferred and superposed at the primary transfer portion T1, and the superposed full-color image is superposed. The intermediate transfer body 67 that collectively transfers the resulting toner image onto the sheet at the secondary transfer portion T2 is the same, and the other points are the same.

The rotary developing device 68 is a rotary main body 68.
a, each of the developer cartridges 69 (Y,
M, C, K) are detachably attached, and the rotary body 68a rotates in the arrow direction at a pitch of 90 degrees, so that the developing roller 63 (Y, M, C,
K) is selectively brought into contact with the surface of the photoconductor 63 to selectively develop it.

The intermediate transfer member 67 is composed of a driving roller 67a, a driven roller 67b, a tension roller 67c, and an intermediate transfer belt stretched around these rollers, and the belt 67 extends in the direction of the arrow in the figure. Circulation driven. The primary transfer portion T1 is formed at the contact portion between the photoconductor 63 and the belt 67, and the secondary transfer portion T2 is formed at the pressure contact portion between the drive roller 67a and the secondary transfer roller 67d provided opposite thereto. It is formed. The secondary transfer roller 67d can be brought into and out of contact with the drive roller 67a (and thus with respect to the intermediate transfer belt 67), and when the secondary transfer roller 67d comes into contact with the drive roller 67a, the secondary transfer portion T2 is formed. Therefore, when forming a color image, the toner images of the respective colors are superimposed on the intermediate transfer belt 67 in a state where the secondary transfer roller 67d is separated from the intermediate transfer belt 67 to form a color image. The secondary transfer roller 67d comes into contact with the intermediate transfer belt 67, and the contact portion (secondary transfer portion T
By feeding the paper from the paper feeding unit 20 to 2), the color image (toner image) is transferred onto the paper.

Also according to this embodiment, the operational effects (a) to (d) according to the first embodiment can be obtained.
Further, according to this embodiment, it is not necessary to provide a photoconductor for each color in the color image forming unit 60, and it is not necessary to provide an exposure unit for each color, as compared with the first embodiment. Since the color image forming unit 60 can be provided at a low cost, the user can change the color image forming apparatus at a lower cost.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various modifications can be appropriately made within the scope of the gist of the present invention.

[0028]

According to the image forming apparatus of any of claims 1 to 4, the apparatus for forming a color image can be used without wasting the apparatus for forming a monochrome image which was initially purchased. The color image forming apparatus can be changed and the color image forming apparatus can be obtained at low cost. Further, according to the image forming apparatus of the second aspect, the color image forming unit can be easily attached to and detached from the apparatus main body, and moreover, the installation area is increased by attaching the color image forming unit to the apparatus main body. There is no problem that it does. According to the image forming apparatus of the third aspect, when the color image including black is formed, the color matching between the black image and the image of the other color is excellent. According to the image forming apparatus of the fourth aspect, a more appropriate black image can be obtained.

[0029]

[Brief description of drawings]

FIG. 1 is a schematic side view showing a first embodiment of an image forming apparatus according to the present invention, in which FIG.
FIG. 3B is a diagram showing a state in which a color image forming unit is attached to the apparatus main body.

FIG. 2 is a schematic side view showing a second embodiment of the image forming apparatus according to the present invention, (a) showing only the apparatus main body,
FIG. 3B is a diagram showing a state in which a color image forming unit is attached to the apparatus main body.

FIG. 3 is a schematic side view showing a third embodiment of the image forming apparatus according to the present invention, (a) showing only the apparatus main body,
FIG. 3B is a diagram showing a state in which a color image forming unit is attached to the apparatus main body.

FIG. 4 is a schematic side view showing a fourth embodiment of an image forming apparatus according to the present invention, (a) showing only the apparatus main body,
FIG. 3B is a diagram showing a state in which a color image forming unit is attached to the apparatus main body.

FIG. 5 is a schematic side view showing a fifth embodiment of the image forming apparatus according to the present invention, (a) showing only the apparatus main body,
FIG. 3B is a diagram showing a state in which a color image forming unit is attached to the apparatus main body.

[Explanation of symbols]

10 Device body 11 Lower case 12 Upper case 20 paper feeder 30 Monochrome image forming unit 40 fixing unit 60 color image forming unit

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Claims (4)

[Claims] 1. A paper feeding section for feeding a sheet, a monochrome image forming section for forming a monochrome toner image on the sheet fed by the sheet feeding section, and a toner image is formed by this monochrome image forming section. An image forming apparatus having an apparatus main body including a fixing unit configured to fix the toner image on a sheet, wherein a color image forming unit capable of forming a color toner image on the sheet is An image forming apparatus, wherein the image forming apparatus is configured to be detachable between the paper feeding unit and the fixing unit. 2. The paper feeding unit and the fixing unit can be separated into upper and lower parts by dividing the casing of the apparatus main body into upper and lower parts,
The image forming apparatus according to claim 1, wherein the color image forming unit is detachably mounted between the both in a laminated manner. 3. The image forming apparatus according to claim 1, further comprising a monochrome image forming section provided for the color image forming unit. 4. The image forming apparatus according to claim 3, wherein the black toner in the monochrome image forming portion of the apparatus main body has a lower glossiness than the black toner in the color image forming unit.