JP2006085064A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of forming a multicolor image, wherein color registration is possible. <P>SOLUTION: Toner image forming apparatus 12Y, 12M, and 12C having the same sectional shape are arranged at intervals D, and the toner image forming apparatus 12C and a toner image forming apparatus 12K having a different sectional shape are arranged at an interval n×D (n is 2 in this embodiment). Thus phases are always matched in transfer start positions of respective colors, and all toner images on respective photoreceptor drums 12 can be accurately put one over another without color misregistration. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus capable of forming multicolor images by electrophotography or ionography.

  In conventional image forming apparatuses that obtain color images by electrophotography or ionography, image forming means for forming a single-color toner image, that is, an electrostatic latent image carrier, is disposed around the image forming means because of its high speed. Further, a charging means for charging the surface of the electrostatic latent image carrier with a predetermined potential, and electrostatic latent image formation for forming an electrostatic latent image on the surface of the electrostatic latent image carrier in response to an external image formation signal A developing means for developing the electrostatic latent image with toner, a transferring means for transferring the toner image formed by the developing means, and the electrostatic latent image carrier not completely transferred by the transferring means. A so-called tandem color image forming apparatus in which a plurality of image forming means composed of cleaning means for removing the residual toner from the electrostatic latent image carrier is arranged is widely used.

  In a tandem color image forming apparatus, four toner image forming units are formed in the same cross section, and the size of the apparatus itself is reduced.

  However, documents printed on the market are not always in color, and are often only black and white.

  In such a case, in the above-described tandem color image forming apparatus, if only the black (hereinafter referred to as K color) toner image forming means is operated, it is possible to prevent other image forming apparatuses from being worn. There is no waste.

  Therefore, in the tandem color image forming apparatus, the intermediate transfer member belt or the paper conveying belt is separated from the toner image forming means of other colors only when the K single color toner image is formed, and the electrostatic latent image carrier is driven. Some of them have a configuration in which they themselves pause (no toner image is formed).

  However, in such a color image forming apparatus, the cross-sectional shape of the K color toner image forming unit is the same as that of the other colors, so the replacement frequency of the K color toner image forming unit is increased and the user is bothered. there were.

  Therefore, in the apparatus disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-162809), only the K-color toner image forming unit is changed in cross-sectional shape from the other color toner image forming units, so The adoption of a diameter electrostatic latent image carrier is disclosed.

An example of a color image forming apparatus is disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 62-205372).
Japanese Patent Laid-Open No. 2002-162809 JP 62-205372 A

  Patent Document 2 (Japanese Patent Application Laid-Open No. Sho 62-205372) discloses that the interval between the electrostatic latent image carriers is set to an integral multiple of the driving roll circumferential length of the conveyor belt in order to achieve color registration. However, although a certain degree of effect is recognized, the problem of color registration has not been completely solved in an actual apparatus.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an image forming apparatus capable of forming a multicolor image capable of adjusting color registration.

  As a result of various inventor's experiments, the inventors have found that in a so-called tandem type color image forming apparatus, there is an optimum condition for the arrangement interval of a plurality of toner image forming means.

  The invention described in claim 1 has been made in view of the above-mentioned fact, and a plurality of toner image forming means for forming a toner image are provided along the moving direction of the transfer member, and the moving transfer member is An image forming apparatus that forms a multi-color toner image by sequentially superimposing the toner images formed by each toner image forming unit, wherein the plurality of toner image forming units are cross-sections along a conveying direction of the transfer member. The second cross-sectional shape includes one toner image forming unit having a first cross-sectional shape and a plurality of toner image forming units having a second cross-sectional shape different from the first cross-sectional shape. Among the plurality of toner image forming units having the toner image forming unit, the other toner image forming unit when the arrangement interval along the moving direction of the transfer member of the two toner image forming units arranged adjacent to each other is D. Forming means is arranged with the toner image forming means and the n (natural number) × D times the interval of the adjacent, and characterized in that.

  Next, the operation of the image forming apparatus according to the first aspect will be described.

  For example, the toner image forming unit includes a photoconductive drum on which a toner image is formed. The photoconductive drum transfers a toner image to a transfer member while rotating, and each photoconductive drum is driven by a single drive source. Driven.

  Even if the drive source rotates at a constant rotation speed, periodic fluctuations that the drive system has from the drive source to the photosensitive drum appear on each photosensitive drum.

  For this reason, although the transfer position of the toner image periodically changes compared to the ideal transfer position, two toner image forming units arranged adjacent to each other among the plurality of toner image forming units having the second cross-sectional shape are formed. The arrangement interval along the moving direction of the transfer member of the unit is D, and the other toner image forming units are arranged with an interval of n (natural number) × D times from the adjacent toner image forming unit. Since the phases are always aligned at the transfer start position, there is no relative color shift between the colors.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the toner image forming means having the second cross-sectional shape are continuously arranged and a part of each other overlaps. It is characterized by that.

  Next, the operation of the image forming apparatus according to claim 2 will be described.

  Since the toner image forming means having the second cross-sectional shape are continuously arranged and a part of each other overlaps, the dimension in the arrangement direction can be shortened and the apparatus can be miniaturized.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the toner image forming unit includes an electrostatic latent image forming unit that forms an electrostatic latent image. The electrostatic latent image forming unit of the toner image forming unit formed in a cross-sectional shape has a larger cross-sectional shape than the electrostatic latent image forming unit of the toner image forming unit formed in a second cross-sectional shape. It is characterized by that.

  Next, the operation of the image forming apparatus according to the third aspect will be described.

  4. The image forming apparatus according to claim 3, wherein the electrostatic latent image forming unit of the toner image forming unit formed in the first cross-sectional shape is an electrostatic latent image forming unit of the toner image forming unit formed in the second cross-sectional shape. Since the cross-sectional shape is set to be larger than that of the means, it is possible to provide a margin for arranging components around the electrostatic latent image forming means. For this reason, for example, instead of a laser exposure apparatus provided outside, an image bar in which LEDs, LCDs and the like are arranged in a line can be arranged around the electrostatic latent image forming unit. Since LEDs, LCDs, and the like do not require mechanical preparation such as rotation of a polygon mirror, so-called FPOT (First Print Out Time) can be shortened.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the plurality of toner image forming units having the second cross-sectional shape are integrated. It is characterized by.

  Next, the operation of the image forming apparatus according to the fourth aspect will be described.

  For example, as described in claim 2, in order to reduce the size of the apparatus, in the plurality of toner image forming units having the second cross-sectional shape, the plurality of toners are adjacent to each other and partially overlap each other. When the image forming units are continuously arranged, for example, even if only the central toner image forming unit is taken out, another adjacent toner image forming unit interferes and cannot be taken out. In this case, the toner image forming means may be removed in order from the end, but the operation becomes complicated.

  In general printers, there are many cases where other devices are arranged on the left and right sides of the apparatus. Therefore, it is preferable for the user to be able to access the apparatus from the front side of the apparatus. In many cases, access is made from the front side of the apparatus.

  In the image forming apparatus according to claim 4, since the plurality of toner image forming units having the second cross-sectional shape are integrated, the plurality of toner image forming units having the second cross-sectional shape can be operated in a single operation. Access from the same direction as the insertion and removal of the paper cassette and the access to the manual cassette, so-called One Way Access, is possible.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the toner image forming means having the second cross-sectional shape for forming a yellow toner image, magenta A toner image forming unit having the second cross-sectional shape for forming the toner image, a toner image forming unit having the second cross-sectional shape for forming the cyan toner image, and the first image forming the black toner image. And a toner image forming unit having a cross-sectional shape as described above.

  Next, the operation of the image forming apparatus according to the fifth aspect will be described.

  In the image forming apparatus according to claim 5, since a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image can be obtained, a full color toner image is obtained by superimposing these images. be able to.

  In addition, since the most frequently used black is assigned to one toner image forming unit having the first cross-sectional shape, the toner image forming unit for other colors is increased in size and the toner capacity is increased. By increasing it, the replacement frequency of the K color can be lowered, and the user's work frequency can be reduced.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, any one of the toner image forming unit having the second cross-sectional shape and the transfer member is provided. It is characterized by comprising contact / separation means for contacting / separating with respect to the other.

  Next, the operation of the image forming apparatus according to the sixth aspect will be described.

  In the image forming apparatus according to claim 6, for example, the most frequently used color, for example, black is assigned to the toner image forming unit having the first cross-sectional shape, and the other colors are assigned to the second first cross-sectional shape. Assigned to the toner image forming means.

  In the case of printing only characters, that is, in the case of black and white printing, toners of yellow, cyan, and magenta are not used, so that the toner image forming means having the second cross-sectional shape is separated from the transfer member.

  As a result, useless contact between the transfer member and the unused toner image forming means can be avoided, and wear of other unused toner image forming means can be prevented when using a single color.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the transfer member has an endless belt shape, and the D has an endless belt shape. Further, it is characterized in that it is set to a natural number times the circumference of the drive roll for driving the transfer member.

  Next, the operation of the image forming apparatus according to the seventh aspect will be described.

  The drive roll that drives the endless belt-shaped transfer member is driven until the driving force reaches the drive roll from the drive source via a gear, belt, etc., even if the rotational speed on the drive source side such as a motor is constant. Fluctuations with a periodicity (changes in a sine wave. One cycle per rotation) appears.

  For this reason, the transfer position of the toner image changes periodically compared with the ideal transfer position, but the interval D of the toner image forming means is set to the natural length of the drive roll that drives the transfer member having an endless belt shape. When set to several times, the phases are always aligned at the transfer start positions of the respective colors, so that the relative color misregistration of the respective colors does not occur.

  According to an eighth aspect of the present invention, a plurality of toner image forming means for forming a toner image are provided along the moving direction of the transfer member, and the toner image formed by each toner image forming means on the moving transfer member. In which a plurality of toner image forming units are formed in a first cross-sectional shape along a conveying direction of the transfer member. One toner image forming means and a plurality of toner image forming means having a second cross-sectional shape different from the first cross-sectional shape, and among the plurality of toner image forming means having the second cross-sectional shape, When the arrangement interval along the moving direction of the transfer member of two toner image forming units arranged adjacent to each other is D, the other toner image forming units And a first driving state in which only the toner image forming unit having the first cross-sectional shape is operated, and the first cross-sectional shape is arranged with an interval of n (natural number) × D times from the image forming unit. The image forming apparatus includes a switching unit capable of switching to a second driving state in which both the toner image forming unit and the toner image forming unit having the second cross-sectional shape are driven.

  Next, the operation of the image forming apparatus according to the eighth aspect will be described.

  The image forming apparatus according to the eighth aspect has the following function in addition to the same function as the first aspect.

  That is, the switching unit causes only the toner image forming unit having the first cross-sectional shape to operate, the toner image forming unit having the first cross-sectional shape, and the toner having the second cross-sectional shape. Since it is possible to switch to the second driving state in which both the image forming unit and the image forming unit are driven, for example, a frequently used color, for example, black is assigned to the toner image forming unit having the first cross-sectional shape, and monochrome printing is performed. To obtain a toner image having the second cross-sectional shape, only the toner image forming unit having the first cross-sectional shape is driven and the toner image forming unit having the second cross-sectional shape is not driven. The life of the forming means (due to wear etc.) can be extended.

  As described above, according to the image forming apparatus of the first aspect, it is possible to form a multicolor image in which color misregistration is suppressed as compared with the related art.

  According to the image forming apparatus of the second aspect, there is an excellent effect that the apparatus can be downsized.

  According to the image forming apparatus of the third aspect, it is possible to dispose an image bar around the electrostatic latent image forming unit, which makes it possible to shorten FPOT (First Print Out Time). It has an excellent effect.

  According to the image forming apparatus of the fourth aspect, there is an excellent effect that the apparatus can be accessed from the same direction, that is, so-called One Way Access.

  According to the image forming apparatus of the fifth aspect, for example, there is an excellent effect that the K color replacement frequency can be lowered and the user's work frequency can be reduced.

  According to the image forming apparatus of the sixth aspect, there is an excellent effect that wear of other unused toner image forming means can be prevented when using a single color.

  According to the image forming apparatus of the seventh aspect, there is an excellent effect that the relative color misregistration of each color does not occur even if the movement of the transfer member varies.

  According to the image forming apparatus of the eighth aspect, there is an excellent effect that it is possible to extend the life of the toner image forming means that is less frequently used.

[First Embodiment]
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a partial cross-sectional view for explaining a color image forming apparatus 10 according to a first embodiment of the present invention.

  As shown in FIG. 1, the image forming apparatus 10 of the present embodiment includes four toner image forming apparatuses, that is, a toner image forming apparatus 12Y that forms a yellow (Y color) image, and a magenta (M color) image. A toner image forming apparatus 12M for forming, a toner image forming apparatus 12C for forming a cyan (C color) image, and a toner image forming apparatus 12K for forming a black (K color) image are provided.

  The toner image forming apparatus 12Y, the toner image forming apparatus 12M, and the toner image forming apparatus 12C have the same cross-sectional shape, and only the toner image forming apparatus 12K has a different cross-sectional shape from the other toner image forming apparatuses.

  Below the toner image forming apparatuses 12Y, 12M, 12C, and 12K, an intermediate transfer unit including a drive roll 14 that is rotated by a drive device (not shown), a driven roll 16, and an intermediate transfer belt 18 that is stretched between these rolls. 20 is arranged.

  As shown in FIG. 2, the toner image forming apparatus 12Y will be described as an example. The known photosensitive drum 22 made of an inorganic or organic material, and the above-described forms selected from contact, non-contact, brush, roll, etc. A known charging unit 24 for charging the surface of the photosensitive drum 22 with a predetermined potential, and an electrostatic latent image formed by the exposure unit 26 on the surface of the photosensitive drum 22 charged by the charging unit 24 with toner. Developing means 28 selected from contact, non-contact, brush, one-component and two-component forms, a toner hopper 30 for supplying toner to the developing means 28, and a toner image formed by the developing means 28 A known transfer means 32 selected from forms such as a roll, a brush, a blade, and a corotron, and an untransferred toner remaining on the surface of the photosensitive drum 22. Cleaning blade, from a known cleaning means 34 which is selected from forms such as a brush, it is formed.

  The image forming apparatus 10 according to the present embodiment includes a black toner image forming apparatus 12K having different use frequencies in four colors used in an electrophotographic process, and other three color toner image forming apparatuses (toner image forming apparatuses). 12Y, M, C) are different device configurations having different cross-sectional shapes. Specifically, the black toner image forming apparatus 12K is made larger than the other three color toner image forming apparatuses (toner image forming apparatuses 12Y, 12M, 12C) (for example, the capacity of the toner hopper 30 is large). In addition, waste is eliminated by dividing the consumable replacement period between the black toner image forming apparatus 12K and the other three color toner image forming apparatuses.

  Here, in the toner image forming apparatuses 12Y, 12M, and 12C, the intervals between the photosensitive drums 22 are equal (arrangement pitch D), and the photosensitive drums 22 of the toner image forming apparatus 12C and the photosensitive elements of the toner image forming apparatus 12K. The arrangement pitch of the body drums 22 is set to a natural number (n) times the arrangement pitch D of the photosensitive drums 22 of the toner image forming apparatuses 12Y, 12M, and 12C.

  In this embodiment, the arrangement pitch D of the photosensitive drums 22 of the toner image forming apparatuses 12Y, 12M, and 12C having the same cross-sectional shape is 70 mm, and the photosensitive drum 22 of the toner image forming apparatus 12C and the toner image forming apparatus 12K. The arrangement pitch of the photosensitive drums 22 is twice D, that is, 140 mm (70 mm × 2).

In this embodiment, the diameter of the photosensitive drum 22 of the toner image forming apparatuses 12Y, 12M, and 12C is 24 mm, and the diameter of the photosensitive drum 22 of the toner image forming apparatus 12K is 30 mm.
(Function)
Next, the operation of the image forming apparatus 10 of this embodiment will be described.

  In each toner image forming apparatus, the surface of the photosensitive drum 22 is charged by the charging unit 24, and the surface of the photosensitive drum 22 charged by the charging unit 24 is scanned with the light beam from the exposure unit 26 to electrostatic latent image. An image is formed. The electrostatic latent image is developed with toner of the developing unit 28 to become a toner image, and the toner image is transferred to the intermediate transfer belt 18 between the photosensitive drum 22 and the transfer unit 32.

  On the intermediate transfer belt 18, a yellow toner image is transferred to the toner image forming device 12Y, a magenta toner image is transferred by the toner image forming device 12M, and a cyan toner image is transferred by the toner image forming device 12C. The black toner image is transferred by the image forming apparatus 12K, whereby a color toner image in which each color is overlapped is formed on the intermediate transfer belt.

  Thereafter, the color toner image is transferred to a sheet and fixed by a fixing device (not shown).

  In the image forming apparatus 10 of the present embodiment, the arrangement interval of the toner image forming apparatuses 12Y, 12M, 12C having the same cross-sectional shape is D, and the toner image forming apparatus 12K having a different cross-sectional shape from the toner image forming apparatus 12C is n (In the present embodiment, 2) Since it is arranged with an interval of × D, the phases are always aligned at the transfer start positions of the respective colors, and all the toner images on the respective photosensitive drums 12 can be accurately superimposed without color misregistration. I can do it.

In this embodiment, n = 2. However, when the cross-sectional shape of the toner image forming apparatus 12K is larger than that of the other toner image forming apparatuses 12Y, 12M, 12C, the n is a natural number of 2 or more. It ’s fine.
[Second Embodiment]
The image forming apparatus 10 according to the second embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 3, the image forming apparatus 10 of the present embodiment changes the position of the toner image forming apparatus 12K with respect to the first embodiment, and also arranges the toner image forming apparatuses 12Y, M, C, and K. The pitch is changed.

  Here, the toner image forming apparatus 12Y, the toner image forming apparatus 12M, the toner image forming apparatus 12K, and the toner image forming apparatus 12C are arranged in this order from the left side of the drawing, and the arrangement of the toner image forming apparatus 12Y and the toner image forming apparatus 12M is arranged. The pitch is D, and the arrangement pitch between other toner image forming apparatuses is D × n.

In addition, about an effect, it is the same as that of 1st Embodiment.
[Third Embodiment]
The image forming apparatus 10 according to the third embodiment will be described with reference to FIGS. 4 and 5. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 4, in the image forming apparatus 10 of the present embodiment, the toner image forming apparatus 12K and the other toner image forming apparatuses 12Y, 12M, 12C, and 12C differ only in the size of the toner hopper 30. The other components have the same configuration (by the way, the diameter of the photosensitive drum 22 is 24 mm).

  Therefore, the toner image forming apparatuses 12Y, 12M, 12C, and 12K can share internal components other than the toner hopper 30.

  FIG. 5 shows a main part of the drive system of the photosensitive drum 22 of each of the toner image forming apparatuses 12Y, 12M, 12C, and 12K.

  In FIG. 5, reference numeral 36Y denotes a gear attached to the drive shaft of the photosensitive drum 22 of the toner image forming apparatus 12Y, reference numeral 36M denotes a gear attached to the drive shaft of the photosensitive drum 22 of the toner image forming apparatus 12M, and reference numeral 36C. Represents a gear mounted on the drive shaft of the photosensitive drum 22 of the toner image forming apparatus 12C, and reference numeral 36K represents a gear mounted on the drive shaft of the photosensitive drum 22 of the toner image forming apparatus 12K.

  Reference numeral 38 denotes an idler gear, which connects the gears of the photosensitive drum 22 as shown in FIG.

  The gears 36Y, 36C, 36K are of the same size (pitch circle, number of teeth). These idler gears 38 are of the same size (pitch circle, number of teeth).

  In this embodiment, since the interval between the toner image forming apparatus 12C and the toner image forming apparatus 12K is set wider than the interval between the other toner image forming apparatuses, one idler gear is used between the other toner image forming apparatuses. 38, three idler gears 38 are disposed between the toner image forming apparatus 12C and the toner image forming apparatus 12K.

  A gear for receiving a driving force from a driving means (for example, a motor) (not shown) may be any of these. In this embodiment, the gear between the toner image forming apparatus 12C and the toner image forming apparatus 12K. A driving force from a driving means (not shown) is inputted to the center idler gear 38 among the three idler gears 38.

Other functions and effects are the same as those of the first embodiment.
[Fourth Embodiment]
The image forming apparatus 10 according to the fourth embodiment will be described with reference to FIG. The present embodiment is a modification of the third embodiment, and the same components as those of the third embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the present embodiment, the arrangement pitch of the toner image forming apparatuses 12C, 12K is longer than the arrangement pitch of the other toner image forming apparatuses 12Y, 12M, 12C.

  In the case of such an arrangement, the exposure means 26 makes laser beams from a plurality of laser light sources incident on a single polygon mirror, and the laser beam reflected by the polygon mirror is optically applied to a plurality of mirrors, lenses, and the like. In the case where each photosensitive drum 22 is irradiated via the system, the optical path length from the polygon mirror to the photosensitive drum 22 of the toner image forming apparatus 12K is longer than the optical path length to the other photosensitive drums 22. As a result, there is a problem that the optical system corresponding to the photosensitive drum 22 of the toner image forming apparatus 12K is more complicated than the optical system for other colors.

  As shown in FIG. 6, in the image forming apparatus 10 of this embodiment, in the toner image forming apparatuses 12Y, 12M, and 12C, the photosensitive drum 22 is exposed with the laser beam from the exposure unit 26, whereas the toner image forming is performed. Since the photosensitive drum 22 of the apparatus 12K is configured to expose with a light beam from the image bar 35 in which LEDs, LCDs, and the like provided in the toner image forming apparatus 12K are arranged in a straight line, the photosensitivity of the toner image forming apparatus 12K. The exposure means 26 is not complicated for the body drum 22, and the configuration of the entire image forming apparatus 10 can be simplified.

  Further, since the photosensitive drum 22 of the toner image forming apparatus 12K is exposed with the light beam from the image bar 35, FPOT can be improved when a black and white toner image is obtained. For example, it is possible to shorten the monochrome copy discharge time in an apparatus in which the image forming apparatus 10 is combined with a scanner, that is, a so-called (Multi Function Printer).

Other functions and effects are the same as those of the first embodiment.
[Fifth Embodiment]
The image forming apparatus 10 according to the fifth embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 7, in the image forming apparatus 10 of this embodiment, the toner image forming apparatuses 12Y, 12M, 12C, and 12K are all provided with an image bar 35, and the exposure unit 26 is omitted instead.

  The toner image forming apparatuses 12Y, 12M, and 12C have the same cross-sectional shape, but a part of the toner image forming apparatus on the right side of the drawing overlaps the toner image forming apparatus on the left side of the drawing (a so-called overhang structure above and below). The toner image forming apparatuses 12Y, 12M, 12C, 12C, 12C, 12C, and 12C are arranged in a single unit (a so-called Customer Replaceable Unit) 13 with a narrow arrangement pitch.

  Reference numeral 45 denotes fixing means for fixing the toner image.

  Here, in the image forming apparatus 10 of the present embodiment, the right side of the drawing is the front of the apparatus, and the user can perform various operations from the front side of the apparatus (arrow F direction side).

  The image forming apparatus 10 includes an exterior case 40. A paper cassette 42 that can be pulled out to the front side of the apparatus is disposed below the exterior case 40, that is, below the toner image forming apparatuses 12Y, 12M, and 12C. Yes. In addition, a manual feed cassette 44 that allows insertion of sheets of various sizes is disposed on the front side of the apparatus in a protruding state.

  The upper part of the exterior case 40 is a paper tray from which paper on which an image is formed is discharged.

  The exterior case 40 has, for example, an upper half that is detachable or open so that the inside can be exposed. It can be easily exchanged by accessing from.

  Since the image forming apparatus 10 of the present embodiment is configured as described above, when replacing the color toner image forming apparatuses 12Y, 12M, 12C, the toner image forming apparatuses 12Y, 12M, 12M, 12D, 12M, 12D, 12M Access to the removal of C and K is the same direction as the insertion / removal direction of the paper cassette 42 and the access direction (left / right direction in the drawing) to the manual feeding cassette 44.

  Therefore, an object can be placed on both sides of the image forming apparatus 10 (front and back direction in FIG. 7), and space can be effectively used.

  When the toner image forming apparatuses 12Y, 12M, and 12C having the overhang structure are made independent, the direction different from the insertion / removal direction of the paper cassette 42 and the access direction to the manual cassette 44, that is, the vertical direction of the drawing. It must be inserted and removed in the direction, and no objects can be placed on one side (the front or back side of the drawing) of the apparatus.

  In this embodiment, since the exposure unit 26 is not provided above the toner image forming apparatuses 12Y, 12M, and 12C, the image forming apparatus 10 can be downsized.

In addition, since all the photosensitive drums 22 of the toner image forming apparatuses 12Y, 12M, 12C, and 12K are exposed with the light beam from the image bar 35, FPOT is improved regardless of whether it is black and white or color.
[Sixth Embodiment]
The image forming apparatus 10 according to the sixth embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same structure as embodiment mentioned above, and the description is abbreviate | omitted.

  As shown in FIG. 8B, the configuration of the intermediate transfer unit 20 is different in the image forming apparatus 10 of the present embodiment.

  The driven roll 16 and the transfer means 32 which is a roll are supported by the sub-frame 46, respectively.

  The sub-frame 46 is provided so as to be swingable (in the direction of arrow A) about the rotation axis of the transfer means 32 on the right side of the drawing closest to the drive roll 14.

  A plunger 48A of an electromagnetic solenoid 48 is connected to the left end of the subframe 46 in the drawing.

  Although not shown in the drawings, each photosensitive drum 22 in this embodiment also receives the driving force from the motor via a gear train as shown in FIG. An electromagnetic clutch (switching means of the present invention) is provided between the corresponding gears 36Y, 36C, 36K.

  Therefore, only the desired photosensitive drum 22 is driven by connecting the electromagnetic clutch, and the driving force is not transmitted (that is, does not rotate) to the photosensitive drum 22 with the electromagnetic clutch disconnected.

  In the image forming apparatus 10 of this embodiment, when obtaining a color image, the intermediate transfer belt 18 is brought into contact with each photosensitive drum 22 as shown by a solid line in FIG. The photosensitive drum 22 is rotated.

  On the other hand, when obtaining a black and white image, the electromagnetic solenoid 48 is driven to lower the subframe 46, and the intermediate transfer is performed from each photosensitive drum 22 of the toner image forming apparatuses 12Y, 12M, 12C, as indicated by a two-dot chain line. The belt 18 is separated, the intermediate transfer belt 18 is brought into contact only with the photosensitive drum 22 of the toner image forming apparatus 12K, and the electromagnetic clutches corresponding to the photosensitive drums 22 of the toner image forming apparatuses 12Y, 12M, 12C are disengaged, Only the electromagnetic clutch corresponding to the photosensitive drum 22 of the toner image forming apparatus 12K is connected.

  As a result, when the black and white image is formed, the driving of the toner image forming apparatuses 12Y, 12M, and 12C stops and is separated from the intermediate transfer belt 18, so that the photosensitive drums 22 of the toner image forming apparatuses 12Y, 12M, and 12C Wear due to the intermediate transfer belt 18 is eliminated, and the life of the toner image forming apparatuses 12Y, 12M, 12C can be extended.

  In the above-described embodiment, the toner image transferred to the intermediate transfer belt 18 is transferred to paper. However, the intermediate transfer belt 18 is used as a paper transport belt, and the toner images are sequentially applied to the paper transported by the paper transport belt. It is good also as a structure which overlaps.

  The image forming apparatus is of a so-called electrophotographic system in which an electrostatic latent image is formed by irradiating a charged photoconductor surface with a light beam, and the electrostatic latent image is developed with toner. In the present invention, it is possible to form an electrostatic latent image on an insulating recording medium by irradiating the recording medium with ions generated by air discharge controlled by a control electrode, and developing this with toner. The present invention can also be applied to a so-called ionographic image forming apparatus that obtains a visual image.

1 is a configuration diagram of a main part when an image forming apparatus according to a first embodiment is viewed from a side. 2 is a cross-sectional view of the toner image forming apparatus. FIG. FIG. 5 is a configuration diagram of a main part when an image forming apparatus according to a second embodiment is viewed from a side surface. FIG. 10 is a configuration diagram of a main part when an image forming apparatus according to a third embodiment is viewed from a side. It is a figure which shows the gear train which drives a photosensitive drum. FIG. 10 is a configuration diagram of a main part when an image forming apparatus according to a fourth embodiment is viewed from a side surface. FIG. 10 is an overall configuration diagram of an image forming apparatus according to a fifth embodiment viewed from the side. (A) is a block diagram of the principal part which looked at the image forming apparatus concerning a 6th embodiment from the side, and (B) is a side view of an intermediate transfer means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12Y Toner image forming means 12M Toner image forming means 12C Toner image forming means 12K Toner image forming means 14 Drive roll 18 Intermediate transfer belt (transfer member)
22 Photosensitive drum (electrostatic latent image forming means)
46 Subframe (contact / separation means)
48 Electromagnetic solenoid

Claims (8)

A plurality of toner image forming means for forming a toner image are provided along the moving direction of the transfer member, and the toner images formed by the respective toner image forming means are sequentially superposed on the moving transfer member to form a multicolor toner. An image forming apparatus for forming an image,
The plurality of toner image forming means includes a toner image forming means in which a cross-sectional shape along the conveying direction of the transfer member is formed in a first cross-sectional shape, and a second cross-section different from the first cross-sectional shape. A plurality of toner image forming means having a shape,
Among the plurality of toner image forming units having the second cross-sectional shape, when the arrangement interval along the moving direction of the transfer member of two toner image forming units arranged adjacent to each other is D, the other The image forming apparatus is characterized in that the toner image forming means is arranged with an interval of n (natural number) × D times from the adjacent toner image forming means. The image forming apparatus according to claim 1, wherein the toner image forming units having the second cross-sectional shape are continuously arranged. The toner image forming means includes an electrostatic latent image forming means for forming an electrostatic latent image,
The electrostatic latent image forming unit of the toner image forming unit formed in the first cross-sectional shape is more cross-sectional than the electrostatic latent image forming unit of the toner image forming unit formed in the second cross-sectional shape. The image forming apparatus according to claim 1, wherein the image forming apparatus has a large shape. 4. The image forming apparatus according to claim 1, wherein a plurality of toner image forming units having the second cross-sectional shape are integrated. 5. A toner image forming unit having the second cross-sectional shape for forming a yellow toner image, a toner image forming unit having the second cross-sectional shape for forming a magenta toner image, and the second for forming a cyan toner image. 5. The toner image forming means having a cross-sectional shape and a toner image forming means having the first cross-sectional shape for forming a black toner image. 6. The image forming apparatus described in 1. 6. A contact / separation unit for contacting / separating either one of the toner image forming unit having the second cross-sectional shape and the transfer member with respect to the other. The image forming apparatus according to any one of the above. The transfer member has an endless belt shape, and the D is set to a natural number times the circumference of a drive roll that drives the transfer member in an endless belt shape. The image forming apparatus according to claim 1. A plurality of toner image forming means for forming a toner image are provided along the moving direction of the transfer member, and the toner images formed by the respective toner image forming means are sequentially superposed on the moving transfer member to form a multicolor toner. An image forming apparatus for forming an image,
The plurality of toner image forming means includes a toner image forming means in which a cross-sectional shape along the conveying direction of the transfer member is formed in a first cross-sectional shape, and a second cross-section different from the first cross-sectional shape. A plurality of toner image forming means having a shape,
Among the plurality of toner image forming units having the second cross-sectional shape, when the arrangement interval along the moving direction of the transfer member of two toner image forming units arranged adjacent to each other is D, the other The toner image forming means is arranged with an interval of n (natural number) × D times from the adjacent toner image forming means,
A first driving state in which only the toner image forming means having the first cross-sectional shape is operated; the toner image forming means having the first cross-sectional shape; and the toner image forming means having the second cross-sectional shape; An image forming apparatus comprising switching means capable of switching to a second driving state for driving both of the first and second driving states.

Images