JPH09160397A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable carrying transfer material and preventing the transfer material from being wound around an image carrier, without adopting a carrying belt of the transfer material. SOLUTION: This device is provided with four photoreceptor drums 10Y, 10M, 10C and 10BK parallelly disposed in a row, and transferring rollers 5Y, 5M, 5C and 5BK arranged in roll contact with these photoreceptor drums, and a transfer paper sheet is carried while allowed to pass through in-between respective photoreceptor drum and several transfer roller. A guide mechanism 50 for guiding carriage of the transfer paper sheet is provided with the fixed rear side guides 51, 52 and 54 for guiding and holding the rear side of the transfer paper sheet, and first and second guide members 53a extending along the carrying direction in state of being held in contact with the photoreceptor drums, and made possible to come into contact with a non-image forming area of a surface side of the transfer paper sheet. The first and the second guide members is severally shifted by a shifting mechanism according to the size of the transfer paper sheet, and a space between these guide members is adjusted.

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 full-color copying machine, a business color copying machine, and a color printer, which forms an image on a transfer material using a plurality of image carriers.

[0002]

2. Description of the Related Art In recent years, in response to the color orientation of offices,
A full color copier is provided. A four-tandem photosensitive drum tandem system is known as one of full-color copying machine systems. In this method, four photoconductor drums are arranged in parallel, and toner images of different colors are formed on the respective photoconductor drums by using toners of yellow, magenta, cyan, and black, and one transfer material is formed. This is a system in which a toner image is sequentially transferred onto the above and the colors are overlapped to obtain a full-color image.

More specifically, this copying machine has four sets of image forming sections corresponding to four color images. Each image forming unit is configured to include a photoconductor drum and a charging device, an exposure device, a developing device, a transfer device, a cleaning device, and the like that are arranged around the photoconductor drum. The image forming sections are arranged in parallel.

Further, below the image forming section, there is provided a conveyor belt which travels in contact with the four photosensitive drums. Then, the conveyor belt is driven to run at the same speed as the peripheral speed of the photosensitive drum.

In the image forming section, four color toner images are formed on the photosensitive drums respectively, and these toner images are sequentially transferred onto the transfer material conveyed by the conveyor belt at a predetermined timing. . The transfer material on which the toner images of four colors are superposed is sent to the fixing device, and the toner images are fused and fixed and then discharged.

Normally, when the transfer material is conveyed to the transfer position of the photosensitive drum and a transfer electric field is applied to the transfer material at the transfer position, dielectric polarization occurs inside the transfer material, and the transfer material is applied to the peripheral surface of the photosensitive drum. I try to wrap it around. Therefore, in a normal copying machine, a transfer material charge eliminator is provided immediately after the transfer position to apply a charge removing electric field, thereby removing the dielectric polarization inside the transfer material generated by the transfer electric field, and removing the transfer material to the photosensitive drum. Prevents wrapping.

However, when the charge eliminating device is provided in a four-tandem tandem type full-color image forming apparatus, it is necessary to provide four charge eliminating devices corresponding to the four photosensitive drums immediately after the transfer positions. Therefore, the manufacturing cost of the device is increased and the device is increased in size, and a large amount of ozone is generated from these static eliminators, which is not desirable in terms of environmental resistance.

Therefore, the conventional 4 constructed as described above is used.
In the continuous tandem type full-color image forming apparatus, the transfer material is conveyed by the conveyor belt, and the transfer material is prevented from being wound around the photosensitive drum. That is, the forces due to the dielectric polarization generated inside the transfer material and on the transfer belt are generated so as to be attracted to each other, and the electrostatic attraction force acts on the transfer material and the transfer material transfer belt, and the transfer material to the photosensitive drum is transferred. Is prevented from wrapping around.

[0009]

However, the following problems occur when the conveyor belt is used. First, the transport belt is usually an endless seamless belt, so the belt itself is expensive.
Further, dirt on the surface of the conveyor belt adheres to the back surface of the transfer material, and therefore the surface of the conveyor belt needs to be cleaned with a cleaning member. In this case, it is necessary to provide an exhaust toner container for temporarily accumulating the paper dust and residual toner dropped off from the conveyor belt by the cleaning member, and it is also necessary to periodically replace the exhaust toner container.

The endless seamless belt, by its nature, needs to be seamless. The reason why the seam is not formed is that the conveyor belt always runs at the same speed as the photoconductor drum, but since it is in contact with the surface of the photoconductor drum, the seam on the conveyor belt will scratch the surface of the photoconductor drum. There is a high possibility that it will be attached.

For this reason, the transfer material transport belt needs to be an endless seamless belt, but in this case, a die for integrally molding the transport belt is required, and the manufacturing cost becomes high.

Next, for cleaning the conveyor belt, urethane plate is pressed against the surface of the conveyor belt,
A blade cleaning system that removes stains on the surface of the conveyor belt is typical, and the installation of such a cleaner contributes to an increase in the manufacturing cost of the image forming apparatus. Further, the necessity of the toner discharging container and the necessity of exchanging the toner discharging container have a great influence on the price of the image forming apparatus.

As described above, when the conveyor belt is used,
There is a problem in that peripheral devices including a conveyor belt are required, which increases the manufacturing cost of the image forming apparatus.

The present invention has been made in view of the above circumstances, and an object thereof is to inexpensively realize the transfer of the transfer material and the prevention of the transfer material from being wrapped around the image carrier without using a transfer material transfer belt. An object of the present invention is to provide an image forming apparatus capable of performing the above.

[0015]

In order to achieve the above object, the image forming apparatus of the present invention according to claim 1 has a plurality of image bearing members provided with their central axes parallel to each other, and the above image bearing member. A plurality of image forming means for forming an image at rest, a plurality of transfer means provided respectively to face the image carrier and transferring the image formed on the image carrier to a transfer material, and each of the images Conveying means for conveying the transfer material between the carrier and the transfer means, and a fixed backside guide which is arranged along the conveying direction of the transfer material and which guides and holds the non-image transfer surface side of the transfer material. And a front surface side guide that is in contact with the plurality of image bearing materials and extends along the conveyance direction of the transfer material, and guides and holds a non-image forming area on the image transfer surface side of the transfer material. Is characterized by.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising: a plurality of image bearing members provided with their central axes parallel to each other; and a plurality of image forming means for respectively forming images on the image bearing member. , A plurality of transfer means that are respectively provided to face the image carrier and transfer the image formed on the image carrier to a transfer material, and transfer the transfer material between the image carrier and the transfer means. A conveying means for conveying, a fixed back side guide arranged along the conveying direction of the transfer material, for guiding and holding the non-image transfer surface side of the transfer material, and contacting the plurality of image bearing materials. A front surface side guide that extends along the transfer direction of the transfer material, is movably provided in a direction orthogonal to the transfer direction, and guides and holds a non-image forming area on the image transfer surface side of the transfer material. , Move the front side guide Moving means for, input means for inputting a direction size of the perpendicular to the conveying direction of the transfer material, in accordance with the detected size by the input means,
Control means for moving the front side guide by the moving means.

According to a third aspect of the present invention, there is provided an image forming apparatus comprising: a plurality of image bearing members provided with their central axes parallel to each other; and a plurality of image forming means for respectively forming images on the image bearing member. , A plurality of transfer means that are respectively provided to face the image carrier and transfer the image formed on the image carrier to a transfer material, and transfer the transfer material between the image carrier and the transfer means. A conveying means for conveying, a fixed back side guide arranged along the conveying direction of the transfer material, for guiding and holding the non-image transfer surface side of the transfer material, and contacting the plurality of image bearing materials. A front surface side guide that extends along the transfer direction of the transfer material, is movably provided in a direction orthogonal to the transfer direction, and guides and holds a non-image forming area on the image transfer surface side of the transfer material. , Move the front side guide Moving means for the manual feed supply means for supplying a transfer material of any size in the conveying means,
A detecting means for detecting the size of the transfer material supplied by the manual supply means in a direction orthogonal to the carrying direction;
Control means for moving the front side guide by the moving means according to the size detected by the detecting means.

An image forming apparatus according to a fourth aspect of the present invention comprises a plurality of image bearing members provided with their central axes parallel to each other, and a plurality of image forming means for forming images on the image bearing member. , A plurality of transfer means that are respectively provided to face the image carrier and transfer the image formed on the image carrier to a transfer material, and transfer the transfer material between the image carrier and the transfer means. A conveying means for conveying, a fixed back side guide arranged along the conveying direction of the transfer material, for guiding and holding the non-image transfer surface side of the transfer material, and contacting the plurality of image bearing materials. A front surface side guide that extends along the transfer direction of the transfer material, is movably provided in a direction orthogonal to the transfer direction, and guides and holds a non-image forming area on the image transfer surface side of the transfer material. , Move the front side guide Moving means, a storage portion for storing a plurality of transfer materials, a supply means for supplying the transfer material one by one from the storage portion to the transport means, and a direction orthogonal to the transport direction of the transfer material stored in the storage portion. Inputting means for inputting a size in a direction, a manual feeding means for selectively feeding a transfer material of an arbitrary size to the carrying means, and a direction orthogonal to the carrying direction of the transfer material supplied by the manual feeding means Detecting means for detecting the size of the transfer means, and according to the size input by the input means or the size detected by the detecting means, the front side guide is moved by the moving means, and the transfer material is transferred by the manual feeding means. When supplied, by the moving means in accordance with the size detected by the detecting means in preference to the size input by the input means. It is characterized by and a control means for moving the serial surface-side guide.

An image forming apparatus according to a fifth aspect of the present invention includes a plurality of image bearing members provided with their central axes parallel to each other, and a plurality of image forming means for forming images on the image bearing member. , Movably provided between an operating position in contact with the image bearing member and a non-operating position in which the image bearing member is separated from the image bearing member, and the image formed on the image bearing member is used as a transfer material at the operating position. A plurality of transfer means for transferring, a switching means for switching the transfer means between an operating position and a non-operating position, a transport means for transporting the transfer material between the image carrier and the transfer means, and a transfer means for transferring the transfer material. A fixed backside guide that is arranged along the transport direction and guides and holds the non-image transfer surface side of the transfer material, and extends along the transport direction of the transfer material in contact with the plurality of image bearing materials. In addition, A front surface side guide, which is movably provided in a direction orthogonal to the direction, and which guides and holds a non-image forming area on the image transfer surface side of the transfer material; a moving means for moving the front surface side guide; Detection means for detecting the size of the transfer material being conveyed in a direction orthogonal to the conveying direction, and moving the front side guide by the moving means according to the size detected by the detecting means, and moving the same. And a control means for switching the transfer means to the non-operating position by the switching means when the front side guide is moved by the means.

According to the sixth aspect of the image forming apparatus of the present invention, the front side guides are in contact with the plurality of image bearing members and extend along the transfer material conveying direction. , An elongated strip-shaped first contactable to both side edges of the transfer material extending in the transport direction.
And a second guide member, the first and second guide members are provided so as to be movable along a direction orthogonal to the transport direction, and the moving means includes the first and second guide members. It is characterized in that the members are moved in mutually opposite directions to change the distance between the first and second guide members.

According to the sixth aspect of the image forming apparatus of the present invention, the front surface side guides are in contact with the plurality of image bearing members and extend along the transfer material conveying direction. , An elongated strip-shaped first contactable to both side edges of the transfer material extending in the transport direction.
And a second guide member, the first guide member is movably provided along a direction orthogonal to the transport direction, and the moving means moves the first guide member, It is characterized in that the distance between the first and second guide members is changed.

[0022]

According to the image forming apparatus of the present invention constructed as described above, the transfer material conveyed by the conveying means is guided and held by the rear surface side guide whose rear surface side is fixed, and the non-image forming area on the front surface side. Is guided and held by the front side guide. Therefore, the transfer material is stably transported without using a conventional transport belt, and the front side guide prevents the transfer material from being wound around the image carrier.

According to the image forming apparatus of the present invention,
The front surface side guide is moved according to the size of the transfer material, and can stably guide and hold the non-image forming area on the front surface side of the transfer material regardless of the size.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the image forming apparatus of the present invention is applied to a four-tandem tandem type color printer will be described in detail below with reference to the drawings.

As shown in FIGS. 1 and 2, in this color printer, four photosensitive drums 2Y, 2M, and 2 as image bearing members are sequentially arranged with their central axes parallel to each other.
C, 2BK, and the photosensitive drums 2Y, 2M, 2C,
2BK is provided corresponding to each of the photoconductor drums 2
A plurality of image forming units 10Y, 10M, 10C, 10BK for forming yellow, magenta, cyan, and black images on Y, 2M, 2C, and 2BK, respectively, and a sheet 8 as a transfer material for the photosensitive drums 2Y, 2M ,. 2C and 2BK, the paper feed mechanism 20 sequentially conveyed, the photosensitive drum 2Y,
2M, 2C, and 2BK are respectively provided in rolling contact with the photosensitive drum 2 for the sheet 8 conveyed by the sheet feeding mechanism 20.
The transfer rollers 5Y, 5M, 5C, and 5BK function as a plurality of transfer units that transfer the toner images formed on the Y, 2M, 2C, and 2BK, respectively.

Four sets of image forming units 10Y, 10M and 10
Of the C and 10BK, the yellow image forming unit 10Y for forming a yellow toner image will be described in detail as a representative. The magenta image forming unit 10M, the cyan image forming unit 10C, and the black image forming unit 10BK have the same configuration as the yellow image forming unit 10Y to be described below, and the same portions are designated by the same reference numerals. Symbols indicating each color, that is, yellow (Y), magenta (M),
(C) is attached to cyan and (BK) is attached to black, and detailed description thereof is omitted.

Around the photosensitive drum 2Y, a charging device 3Y for charging the surface of the photosensitive drum 2Y, a solid scanning head 1Y, a developing device 4Y for supplying yellow toner, a cleaning device 6Y, and a charge eliminating device 7Y are arranged. Has been done.

In the image forming section 10Y, the solid scanning head 1Y outputs exposure light to the photosensitive drum 2Y in accordance with yellow image data sent from a print control section (not shown). This solid-state scanning head 1Y is
It has a structure in which minute light emitting parts are arranged at equal intervals along the line in the main scanning direction, and the corresponding light emitting parts are individually selected according to the on / off signal sent from the print control part according to the pattern to be printed. Lights up. The light from each issuing unit is imaged on the photoconductor drum 2Y by the same-magnification imaging optical system to expose the surface of the photoconductor drum.

For example, the solid-state scanning head 1Y has a resolution of 4
A 00 DPI LED head array is used, and a selfoc lens array is used in the same-magnification imaging optical system.

The photosensitive drum 2Y has a printing speed of 8 sheets / minute and a process speed of 50 mm / sec.
A drive motor (not shown) rotationally drives the peripheral speed of V. The photoconductor drum 2Y is a charging device 3 including a charging roller having conductivity and provided on the surface of the drum.
Y is charged to a predetermined surface potential. A charging bias power source (not shown) is connected to the charging roller forming the charging device 3Y, and a predetermined charging bias is applied. The charging roller is driven to rotate by coming into contact with the surface of the photosensitive drum 2Y.

The surface of the photosensitive drum 2Y is formed of an organic photoconductor. This photoconductor generally has a high resistance, but has a property that when irradiated with light, the specific resistance of the light irradiated portion changes. Therefore, by irradiating the surface of the charged photoconductor drum 2Y with light corresponding to the yellow print pattern from the solid scanning head 1Y through an equal-magnification imaging optical system, an electrostatic latent image of the yellow print pattern is formed on the photoconductor drum. It is formed on the surface of 2Y.

The photosensitive drum 2Y on which the electrostatic latent image is formed in this way rotates at the peripheral speed V to the developing position. Then, at this developing position, the electrostatic latent image on the photoconductor drum 2Y is developed with yellow toner by the developing device 4Y to form a visible toner image. In the developing device 4Y, a yellow toner formed of resin containing a yellow dye is prepared. The yellow toner is frictionally charged by being agitated inside the developing device 4Y, and has a charge of the same polarity as the electrostatic charge charged on the photosensitive drum 2Y. As the surface of the photosensitive drum 2Y passes through the developing device 4Y, the yellow toner electrostatically adheres only to the latent image portion from which the charge has been removed, and the latent image is developed by the yellow toner, that is, inverted. It is developed.

The photosensitive drum 2Y on which the yellow toner image is formed continues to rotate at the peripheral velocity V, and the transfer roller 5Y is rotated.
To a first transfer position opposite to. On the other hand, the sheet is fed to the first transfer position at a predetermined timing by a sheet feeding mechanism 20 as a feeding unit described later. Then, the yellow toner image is transferred from the photosensitive drum 2Y onto the sheet 8 by the transfer roller 5Y.

The paper feeding mechanism 20 includes the image forming units 10Y and 10Y.
A paper feed cassette 2 arranged below M, 10C and 10BK and containing a large number of papers 8 in a stacked state.
2, a pickup roller 24, a feed roller pair 25, and a registration roller pair 26.

The sheets 8 picked up one by one from the paper feed cassette 22 by the pickup roller 24 are conveyed to the registration roller pair 26 by the feed roller pair 25, further aligned by the registration roller pair 26, and then aligned. 1 is transferred to the transfer position. The peripheral speed of the registration roller pair 26 is set to be the same as the peripheral speed V of the photosensitive drum 2Y. Then, the sheet 8 conveyed to the first transfer position is nipped between the photosensitive drum 2Y and the transfer roller 5Y, and is conveyed to the next transfer position by the photosensitive drum and the transfer roller.

The sheet 8 on which the yellow toner image has been transferred in this manner is then transferred to the second transfer position of the magenta image forming section 10M, the third transfer position of the cyan image forming section 10C,
Further, it is sequentially conveyed to the fourth transfer position of the black image forming unit 10BK, and the magenta toner image, the cyan toner image, and the black toner image are transferred in order on the yellow toner image on the paper 8.

As described above, the registration roller pair 26, the photoconductor drums 10Y, 10M, 10C and 10BK, and the transfer rollers 5Y, 5M, 5C and 5BK constitute a conveying means for conveying the paper through the transfer position. , Paper feed cassette 22, pickup roller 24, feed roller pair 2
Reference numeral 5 constitutes a supply means for supplying the sheet to the conveying means one by one.

The sheet 8 on which the color-superimposed image is formed is sent to the fixing device 30. The fixing device 30 has a heating roller 30a having a heater incorporated therein and a pressure roller 30b which is brought into pressure contact with the heating roller 30a, and the paper 8 passes through the pressure contact portion between the heating roller and the pressure roller, whereby The toner image, which is placed on the sheet 8 by the charge force, is fused and pressure-bonded to be permanently fixed to the sheet 8. The paper 8 on which the fixing is completed is carried onto the paper discharge tray 33 by the discharge rollers 32.

On the other hand, the photosensitive drum 2 which has passed the transfer position
Y is rotationally driven as it is at the peripheral speed V, the residual toner and the paper dust are cleaned by the cleaning device 6Y, the surface potential is made constant by the charge eliminating lamp of the charge eliminating device 7Y, and the charging device 3Y is again charged as necessary. Enter the series of processes from.

In the case of monochromatic printing, image formation is performed by the above-mentioned arbitrary monochromatic image forming unit. At this time, the image forming units other than the selected color do not operate.

On the other hand, the paper feed mechanism 20 guides the paper 8 to the fixing device 30 through the first to fourth transfer positions and prevents the paper from being wound around the photosensitive drums 2Y, 2M, 2C and 2BK. A guide mechanism 50 is provided.

As shown in FIGS. 1 and 2, the guide mechanism 50 includes a paper feed guide 51 that functions as a back side guide for guiding and holding the non-transfer surface of the paper, that is, the back surface.
A plurality of back side holding guides 54, a paper discharge guide 52, and a front side holding guide 53 that functions as a front side guide that guides and holds the transfer side of the sheet, that is, the front side,
These guides are supported by a body frame (not shown) of the printer.

The paper feed guide 51 is formed in a plate shape and is arranged between the registration roller pair 26 and the first transfer position. The distance between the registration roller pair 26 and the first transfer position is set to be equal to or less than the width of the smallest size of the used sheets along the transport direction. for that reason,
All used paper 8 must be a pair of registration rollers 26
The sheet is conveyed to the first transfer position while being sandwiched by. During that time, the paper feed guide 51 holds the back side of the paper 8 and guides it to the first transfer position.

Each of the plurality of back side holding guides 54 is formed in a rectangular plate shape, and is horizontally provided between adjacent transfer rollers. Since four photoconductor drums are provided, three back side holding guides 54 are provided.

Each back side holding guide 54 is formed of a conductive material such as a galvanized copper plate, and is controlled to a predetermined potential. For example, the back side holding guide 54 is connected to the ground of the printer and held at the same potential. This is because the toner image transferred from the photoconductor drum 2 is placed on the paper 8 only by electrostatic force, and therefore when the paper on which the toner image is transferred passes over the back side holding guide 54,
This is to prevent the electrostatic force from being adversely affected.

The paper discharge guide 52 is formed in a plate shape, and extends from the fourth transfer position to the vicinity of the fixing device 30. The distance between the fixing device 30 and the fourth transfer position is
It is set to be equal to or smaller than the width of the smallest size of the used sheets along the transport direction. Therefore, all the used sheets 8 are conveyed to the fixing device 30 in a state of being sandwiched by the photosensitive drum 2BK and the transfer roller 5BK at the fourth transfer position without fail. During that time, the paper ejection guide 52 holds the back side of the paper 8 and guides it to the fixing device 30.

On the other hand, the front side holding guide 53 is composed of first and second guide members 53a, 53 which are formed in an elongated strip shape.
b. These first and second guide members 5
The reference numerals 3a and 53b extend through the first transfer position to the fourth transfer position, and also extend in the transport direction of the paper 8, that is, in the direction orthogonal to the axis of each photoconductor drum.

Further, the first and second guide members 53
a and 53b are stretched substantially horizontally between the first transfer position and the fourth transfer position, and the photoconductor drums 2Y and 2b.
While being in contact with the outer peripheral surfaces of M, 2C, and 2BK, they are pressed against the corresponding photoconductor drums by the transfer rollers 5Y, 5M, 5C, and 5BK.

Further, the first and second guide members 53
The letters a and 53b are set apart from each other by an interval slightly narrower than the width of the sheet 8 in the direction orthogonal to the conveying direction. Further, the paper 8 is supplied on the basis of what is called a paper center, and the first and second guide members 53a, 53 are provided.
b is arranged so that the center between them coincides with the axial center of the photosensitive drum. Therefore, the first and second guide members 53a and 53b are capable of contacting both side edge portions of the sheet 8, that is, the non-image forming area where the toner image is not transferred.

Therefore, the paper 8 sent from the pair of registration rollers 26 is supported and guided on the back side by the paper feed guide 51, a plurality of back side holding guides 54, and the paper discharge guide 52, and on the front side. While being guided by the first and second guide members 53a and 53b of the front side holding guide 53 at both side edge portions thereof, they are sequentially conveyed through the first to fourth transfer positions. The registration roller pair 26
After passing through the sheet, the sheet 8 is conveyed by being sandwiched between the photosensitive drum and the transfer roller and receiving a conveying force from them.

Between the first to fourth transfer positions, the paper feed guide 51, the plurality of back side holding guides 54, and the paper discharge guide 52 are arranged slightly below the tangent lines contacting the four photosensitive drums. First and second guide members 53a,
It is arranged at a predetermined interval with respect to 53b. Therefore, even when the relatively thick sheet 8 is conveyed, an unnecessary load does not act on the sheet.

The end portions of the first and second guide members 53a on the sheet feeding side are located at the first transfer position and the pair of resist rollers 2 from the first transfer position.
It extends above 6. Therefore, even if the leading edge of the sheet 8 supplied from the registration roller pair 26 is fed in a direction different from the first transfer position for some reason, the first
And the second guide members 53a and 53b and the paper feed guide 5
It is possible to reliably guide the sheet 8 to the first transfer position by sandwiching the sheet 8 with the sheet 1.

Further, the first and second guide members 53
The discharge-side ends of a and 53b extend from the fourth transfer position to the upper portion of the fixing device 30. Therefore, the paper 8 that has passed the fourth transfer position is reliably conveyed to the fixing device 30 by the first and second guide members 53a and 53b and the paper discharge guide 52.

First and second guide members 53a, 53
b is formed of polyethylene terephthalate having a thickness of 100 μm and a width of 10 mm, for example. And
Since these guide members 53a and 53b are always in sliding contact with the photoconductor drum, each guide member is treated so as not to damage the photoconductor drum.

That is, as can be seen from FIG. 3, each of the first and second guide members 53a and 53b is cut such that both side edges have the same cutting direction, that is, the cutters are applied from the same direction. In addition, the drooping side formed by cutting faces the side opposite to the surface of the photosensitive drum. Further, an appropriate polishing treatment is applied so that the cut surface becomes smooth.

Incidentally, the first and second guide members 53
The thickness of 100 μm of a and 53b is a numerical value obtained by an experiment. That is, when the thickness is 100 μm or more, at each transfer position, the outer peripheral portion of the transfer roller 5 formed of an elastic body such as rubber is elastically deformed at the portions in contact with the guide members 53a and 53b. It becomes difficult to absorb the thickness of the guide member. Therefore, it becomes difficult for the transfer roller 5 to satisfactorily roll-contact with the corresponding photosensitive drum 2, which causes a transfer failure.

Further, the first and second guide members 53
The widths 10 mm of a and 53b are also numerical values obtained by the experiment. That is, when the width is formed to be 10 mm or more,
This is because sliding friction between the first and second guide members 53a and 53b and the sheet 8 increases, and it becomes difficult to properly convey the sheet.

Further, the reason why each guide member is made of a flexible material such as polyethylene terephthalate is to make it difficult for the surface of the photosensitive drum which comes into contact with the sliding state to be crumpled.

According to the color printer constructed as described above, the paper 8 sent from the registration roller pair 26 is sent.
Is a paper feed guide 51 on the back side and a plurality of back side holding guides 5.
4. While being supported and guided by the paper ejection guide 52, the front side both edge portions of the front side holding guide 53 are
While being guided by the second guide members 53a and 53b, the four color toner images are sequentially transferred onto the sheet 8 by being conveyed through the first to fourth transfer positions in order.

Further, since the both side edges on the front side of the sheet 8 are guided from above by the first and second guide members 53a and 53b, the sheet 8 is not wound around the photosensitive drum when leaving each transfer position. It is prevented by this guide member.

Therefore, according to the color printer according to the present embodiment, the paper can be satisfactorily and reliably transported without using the conventional transport belt, and as a result, the manufacturing cost can be reduced. Become.

In the first embodiment, the first and second guide members 53a and 53b are formed separately, but the end portions of these guide members are connected to each other to form an integral frame shape. It may be formed in.

FIG. 4 and FIG. 5 show a color printer according to the second embodiment of the present invention. According to this embodiment, the structure of the guide mechanism 50 is different from that of the first embodiment described above, and the other structures are the same as those of the first embodiment. Therefore, the same portions are denoted by the same reference numerals, detailed description thereof will be omitted, and only different portions will be described in detail.

According to the second embodiment, the guide mechanism 5
The first and second zero guide members 53a and 53b are configured to be movable according to the size of the paper on which the image is formed. Specifically, the first guide member 53a has a pair of first racks 55a connected to both ends thereof, and these racks are arranged along the axial direction of the photosensitive drum on the side of the second guide member 53b. Has been extended to. Similarly, the second
The guide member 53b has a pair of second racks 55b connected to both ends thereof, and these racks extend toward the first guide member 53b side along the axial direction of the photosensitive drum.

First and second racks 55a, 55b
Are provided so that the heights thereof in the vertical direction are shifted, and the tip end portions are opposed to each other at a predetermined interval. The racks 55a and 55b are movably supported by a main body frame (not shown) of the color printer along the axial direction of the photosensitive drum.

Further, the first and second guide members 53
A drive motor 56a is provided in the vicinity of the sheet feeding side ends of a and 53b.
And a pinion gear 58a is attached to the rotary shaft of the drive motor. And the pinion gear 5
8a is the first and second racks 55a, 55 on the paper feed side.
It is arranged between b and meshes with these racks. Therefore, by driving the drive motor 56a, the first and second racks 55a and 55b are moved in opposite directions.

First and second guide members 53a, 53
A drive motor 56b is disposed in the vicinity of the sheet discharge side end of b, and a pinion gear 58b is attached to the rotation shaft of the drive motor. And the pinion gear 58b is
It is arranged between the first and second racks 55a and 55b on the paper discharge side and meshes with these racks. Therefore, by driving the drive motor 56a, the first and second racks 55a and 55b are moved in opposite directions.

The operation of the drive motors 56a and 56b is controlled by the motor controller 57. The motor control unit 57 is connected to the main control unit 61 of the color printer, and constitutes the control means in the present invention together with the main control unit.
An operation panel 60 as an input means is connected to the main controller. The control means also acts as a detection means for detecting the size of the paper.

According to the color printer configured as described above, by driving the drive motors 56a and 56b, the first and second guide members 53a and 53b are mutually opposed along the axial direction of the photosensitive drum. In the direction of movement, resulting in a change in the spacing between these guide members. Therefore, the drive motor 56 is controlled by the motor control unit 57.
The first and second guide members 5 are controlled according to the size of the paper on which the color image is formed by controlling a and 56b.
Adjust the space between 3a and 53b, regardless of the paper size,
It is possible to always guide the both side edges of the paper surface stably.

FIG. 6 shows a flowchart of the rotation control of the drive motors 56a and 56b. As shown in FIGS. 4 and 6, when the print start button of the operation panel 60 is pressed, the main controller 61 sends the size data of the paper selected by the operation panel 60 to the motor controller 57. The motor control unit 57 includes a size of a standard size paper stored in advance in the printer and a drive motor 5 corresponding to the size.
A data table 62 that records the rotation speeds of 6a and 56b is connected.

Then, the motor control unit 57 reads out the corresponding motor rotation speed from the data table 62 according to the paper size data sent to the motor control unit, and rotationally drives the drive motors 56a and 56b by this motor rotation speed.
Thereby, the first and second guide members 53a, 53
b is moved to both sides of the front surface of the paper of the selected size, that is, the position where it abuts the non-image forming area via the racks 55a and 55b.

First and second guide members 53a, 53
When the movement of b is completed, an end signal is sent to the main control section 61 of the color printer, and the image forming sections 10Y, 10M, 10
Image formation of each color by C and 10BK and conveyance of the sheet 8 are started.

According to the color printer according to the second embodiment having the above-described configuration, the first and second guide members 53a, 5a, 5a and 5b are formed according to the size of the paper on which the image is formed.
Since the interval between the 3b can be adjusted, the sheet can be stably conveyed regardless of the size of the sheet, and the winding of the sheet around the photosensitive drum can be prevented. And since it is not necessary to use a conventional conveyor belt,
It is also possible to reduce the manufacturing cost.

7 and 8 show a color printer according to the third embodiment of the present invention. According to the present embodiment, the manual feed guide 58 functioning as a manual feed means capable of feeding an arbitrary sheet is provided, and the guide mechanism 50 is controlled as compared with the second embodiment described above. The difference is that the other configurations are the same as those in the second embodiment. Therefore, the same parts as those of the second embodiment are designated by the same reference numerals, detailed description thereof will be omitted, and only different parts will be described in detail.

According to the second embodiment, a plate-shaped manual feed guide 58 for guiding the sheet from the outside of the color printer to the registration roller pair 26 is attached to the main body frame (not shown). Also, the manual feed guide 5
On the upper surface of 8, a pair of positioning plates 64 for contacting both side edges of the sheet to be manually fed and aligning the center of the sheet.
Is provided. These positioning plates 64 are interlockingly movable in mutually opposite directions along the axial direction of the photosensitive drum.

Further, on the lower surface side of the manual feed guide 58, there are a CCD, a line sensor, etc. which function as a detection means for detecting the size of the paper set on the manual feed guide, particularly the size in the direction orthogonal to the paper feed direction. An optical sensor 65 is provided. A slit 66 is formed in the manual feed guide 58 so as to face the optical sensor 65, and external light is incident on the entire area of the optical sensor through the slit. Then, the optical sensor 65 outputs the detection signal to the main controller 61.

Then, the first and second guide mechanisms 50
The guide members 53a and 53b are moved according to the size of the paper fed from the paper feed cassette 22 or the size of the paper fed through the manual feed guide 58.

FIG. 9 shows a flowchart of the rotation control of the drive motors 56a and 56b. When the print start button on the operation panel 60 is pressed, the main control unit determines whether the paper feed set by the operation panel is paper feed from the paper feed cassette 22 or manual paper feed. .

When the paper is fed from the paper feed cassette 22,
Similar to the above-described second embodiment, the main control unit 61 sends the size data of the sheet selected by the operation panel 60 to the motor control unit 57. The motor control unit 57 reads the corresponding motor rotation speed from the data table 62 according to the sent paper size data, and rotationally drives the drive motors 56a and 56b by this motor rotation speed.

As a result, the first and second guide members 53a and 53b are brought into contact with the both side edge portions of the front surface of the selected size sheet, that is, the non-image forming area, via the racks 55a and 55b. Be moved.

On the other hand, when manual paper feed is set,
When the paper is set on the manual feed guide 58, the optical sensor 65 detects the size in the direction orthogonal to the paper transport direction, that is, the width, and inputs the size to the main controller 61. For details,
When a sheet is placed on the slit 66 formed in the manual feed guide 58, the sheet blocks the external light, and the external light does not enter the portion of the optical sensor 65 facing the sheet. Then, the optical sensor 65 detects the width of the paper by measuring the length of the portion where external light is not incident.

The detected paper width is sent from the main controller 61 to the motor controller 57 as paper size data. The motor control unit 57 reads the corresponding motor rotation speed from the data table 62 according to the sent paper size data, and the drive motors 56a, 5 are driven by the motor rotation speed.
6b is rotationally driven.

As a result, the first and second guide members 53a and 53b are brought into contact with the both side edges of the front surface of the paper of the selected size, that is, the non-image forming area, via the racks 55a and 55b. Be moved.

First and second guide members 53a, 53
When the movement of b is completed, an end signal is sent to the main control unit 61, and image formation of each color by the image forming units 10Y, 10M, 10C, and 10BK and conveyance of the paper 8 are started.

According to the color printer of the third embodiment configured as described above, the first and second guide members according to the size can be applied to the irregular size paper fed from the manual feed guide as well. The distance between 53a and 53b can be adjusted. Therefore, in both cases of paper feeding from the paper feeding cassette and manual paper feeding, the paper can be stably conveyed regardless of the paper size, and the paper can be prevented from being wound around the photosensitive drum. And since it is not necessary to use a conventional conveyor belt,
It is also possible to reduce the manufacturing cost.

In the third embodiment having the above-mentioned structure, the operation control of the guide mechanism 50 may be performed by giving priority to the manual feed paper.

That is, as shown in FIG. 10, when the print start button of the operation panel 60 is pressed, the main control section 61 is pressed.
First activates the optical sensor 65, and then the manual feed guide 58
The presence or absence of the paper set in is detected. When the paper is set, the size of the paper is detected by the optical sensor 65 at the same time.

The detected paper size data is sent from the main controller 61 to the motor controller 57, and the motor controller 5
7 reads out the corresponding motor rotation speed from the data table 62 according to the sent paper size data, and rotationally drives the drive motors 56a and 56b by this motor rotation speed.

As a result, the first and second guide members 53a and 53b are brought into contact with the both side edge portions of the front surface of the selected size sheet, that is, the non-image forming areas, via the racks 55a and 55b. Be moved.

If the manual sheet is not detected by the optical sensor 65, that is, if the output value of the optical sensor 65 remains the initial value, the main control section 61 determines that the sheet is fed from the sheet cassette 22. The size of the sheet selected by the operation panel is read and the size data is output to the motor controller 57.

The motor control unit 57 reads the corresponding motor rotation speed from the data table 62 according to the sent paper size data, and drives the motor 5 by this motor rotation speed.
6a and 56b are rotationally driven. As a result, the first and second guide members 53a and 53b are connected to the racks 55a and 5a.
Through 5b, the sheet is moved to both side edge portions on the front surface of the selected size sheet, that is, to a position in contact with the non-image forming area.

First and second guide members 53a, 53
When the movement of b is completed, an end signal is sent to the main control unit 61, and image formation of each color by the image forming units 10Y, 10M, 10C, and 10BK and conveyance of the paper 8 are started.

According to the color printer having the above-described configuration, similarly to the third embodiment, the irregular-sized sheets supplied from the manual feed guide can be divided into the first and second sheets depending on their sizes. The distance between the guide members 53a and 53b can be adjusted. Therefore, in both cases of paper feeding from the paper feeding cassette and manual paper feeding, the paper can be stably conveyed regardless of the paper size, and the paper can be prevented from being wound around the photosensitive drum. Further, since it is not necessary to use the conventional conveyor belt, the manufacturing cost can be reduced.

Further, when a sheet is set on the manual feed guide 58, the guide mechanism 50 is controlled by giving priority to the size of the manual feed sheet regardless of the sheet size set by the operation panel 61. Therefore, the user does not have to select the paper size or the manual paper feed on the operation panel, but simply sets the paper on the manual paper feed guide 58 as needed, and the image formation can be automatically performed in the manual paper feed mode. It is possible to improve.

FIGS. 11 to 11 show a color printer according to the fourth embodiment of the present invention. According to the present embodiment, when the positions of the first and second guide members of the guide mechanism are adjusted, the switching mechanism 68 is provided for moving each transfer roller to a position away from the corresponding photosensitive drum. The third embodiment is different from the third embodiment described above, and the other configuration is the same as that of the third embodiment. Therefore, the same parts as those of the third embodiment are designated by the same reference numerals, detailed description thereof will be omitted, and only different parts will be described in detail.

The switching mechanism 68 will be described by taking the yellow image forming section 10Y as a representative. As shown in FIGS. 11 to 13, according to the fourth embodiment, the photosensitive drum 2 is used.
Elliptic cams 70Y are rotatably attached to both ends of the Y center axis (only one is shown). Further, the transfer roller 5Y is moved by the main body frame to the illustrated operating position in which the transfer roller 5Y is in rolling contact with the outer peripheral surface of the photoconductor drum 2Y, and the photoconductor drum and the first and second guide members 53a and 53b.
It is movably supported between a non-operating position (see FIG. 14) separated from (see FIG. 8). The transfer roller 5Y is constantly urged toward the operating position by the pressing springs 71Y that are in contact with both ends of the central shaft.

Guide rollers 72Y are rotatably attached to both ends of the central axis of the transfer roller 5Y. Each of the guide rollers 72Y faces the elliptical cam 70Y and is disposed so as to be able to abut on the peripheral surface of the elliptic cam.

The elliptic cam 70Y has a major axis larger than the diameter of the photosensitive drum 2Y and a minor axis smaller than the diameter of the photosensitive drum 2Y. A plunger 75Y of a solenoid 74Y is connected to one end of the elliptical cam 70Y on the major axis side, and a tension spring 76Y is provided between the other end of the ellipse cam 70Y and the main body frame (not shown).

As a result, each elliptical cam 70Y is normally
It is biased by the tension spring 76Y and is rotated and held at the separated position shown in FIG. In the separated position, the elliptical cam 70Y has its major axis positioned horizontally, and the guide roller 7
Separate from 2Y. Therefore, the transfer roller 5Y is urged to the operating position by the pressing spring 71Y and is brought into rolling contact with the photosensitive drum 2Y. The length of the minor axis of the elliptical cam 70Y and the diameter of the guide roller 72Y are set so that the transfer roller 5Y is brought into rolling contact with the photosensitive drum 2Y under optimum conditions.

On the other hand, when the solenoid 74Y is excited by the driver 78Y under the control of the main controller 61 (see FIG. 8), the plunger 75Y is pulled in and the elliptical cam 70 is pulled.
Y is rotated about 90 degrees to the switching position shown in FIG. 14 against the biasing force of the tension spring 76Y. In the switching position, the elliptical cam 70Y is positioned with its long axis vertical.
The end on the long axis side extends beyond the outer peripheral surface of the photosensitive drum 2Y and pushes down the guide roller 72Y. Therefore,
As shown in FIGS. 14 and 15, the transfer roller 5Y is moved to the non-operating position against the pressing spring 71Y, and the outer peripheral surface of the photosensitive drum 2Y and the first and second guide members 53 are moved.
Separated from a and 53b.

FIG. 16 shows a flowchart of the operations of the guide mechanism 50 and the switching mechanism of the color printer constructed as described above.

That is, when the print start button on the operation panel 60 (see FIG. 8) is pressed, the main controller 61 energizes the solenoids 74Y, 74M, 74C and 74BK via the drivers 78Y, 78M, 78C and 78BK. , Elliptic cams 70Y, 70M, and 70C attached to the photoconductor drums of the image forming units 10Y, 10M, 10C, and 10BK,
70BK is rotated from the separated position to the switching position. As a result, the transfer rollers 5Y, 5M, 5C, and 5BK are moved to the non-operating positions, and the outer peripheral surface of the corresponding photosensitive drum and the first and second guide members 53a and 53b.
Separate from.

Further, the main control section 61 operates the optical sensor 65 almost at the same time to detect the presence / absence of the sheet set in the manual feed guide 58. When the paper is set, the size of the paper is detected by the optical sensor 65 at the same time.

The detected paper size data is sent from the main control unit 61 to the motor control unit 57, and the motor control unit 5
7 reads out the corresponding motor rotation speed from the data table 62 according to the sent paper size data, and rotationally drives the drive motors 56a and 56b by this motor rotation speed.

As a result, the first and second guide members 53a and 53b are brought into contact with the both side edges of the front surface of the paper of the selected size, that is, the non-image forming area, via the racks 55a and 55b. Be moved. At this time, since each transfer roller is held in the non-operating position and separated from the outer peripheral surface of the photosensitive drum, the first and second guide members 5 are
3a and 53b can be easily moved with little resistance.

If the optical sensor 65 does not detect a manual feed sheet, that is, if the output value of the optical sensor 65 remains at the initial value, the main control section 61 determines that the paper is fed from the paper feed cassette 22. The size of the sheet selected by the operation panel is read and the size data is output to the motor controller 57.

The motor control unit 57 reads the corresponding motor rotation speed from the data table 62 according to the sent paper size data, and drives the motor 5 by this motor rotation speed.
6a and 56b are rotationally driven. As a result, the first and second guide members 53a and 53b are connected to the racks 55a and 5a.
Through 5b, the sheet is moved to both side edge portions on the front surface of the selected size sheet, that is, to a position in contact with the non-image forming area. Also in this case, since the transfer rollers are held in the non-operating position and separated from the outer peripheral surface of the photosensitive drum, the first and second guide members 53a and 53b can be easily moved with a small resistance. .

First and second guide members 53a, 53
When the movement of b is completed, an end signal is sent to the main control unit 61, and the main control unit causes the solenoids 74Y, 74M, 74C, 7
Turn off 4BK. Then, the elliptical cams 70Y, 7
0M, 70C and 70BK are tension springs 76, respectively.
It is urged by Y, 76M, 76C, and 76BK to return to the separated position.

Therefore, the transfer rollers 5Y, 5M, 5C, 5
Each of the BKs moves to the operating position and rolls on the outer peripheral surface of the corresponding photoconductor drum. After that, under the control of the main control unit 61, image formation of each color by the image forming units 10Y, 10M, 10C and 10BK and conveyance of the paper 8 are started.

According to the color printer configured as described above, the distance between the first and second guide members 53a and 53b is adjusted according to the size of the irregular size paper fed from the manual feed guide. Can be possible Therefore, in both cases of paper feeding from the paper feeding cassette and manual paper feeding, the paper can be stably conveyed regardless of the paper size, and the paper can be prevented from being wound around the photosensitive drum. Further, since it is not necessary to use the conventional conveyor belt, the manufacturing cost can be reduced.

When a sheet is set on the manual feed guide 58, the guide mechanism 50 is controlled by giving priority to the size of the manual feed sheet regardless of the sheet size set by the operation panel 61. Therefore, the user does not have to select the paper size or the manual paper feed on the operation panel, but simply sets the paper on the manual paper feed guide 58 as needed, and the image formation can be automatically performed in the manual paper feed mode. It is possible to improve.

Furthermore, according to the fourth embodiment, since the first and second guide members 53a and 53b can be moved in a state where the transfer roller is separated from the photosensitive drum, these guide member and the photosensitive member Friction with the body drum is reduced, and the guide member can be easily and quickly moved without damaging the outer peripheral surface of the photoconductor drum.

In the first to fourth embodiments described above, the color printer uses a so-called center reference, in which a sheet as a transfer material is supplied with its center aligned in the axial direction of the photosensitive drum. However, the present invention is not limited to this, and may be applied to a so-called one-sided reference color printer in which one side edge of a sheet is aligned and the sheet is fed.

FIG. 17 shows the structure of a one-sided reference color printer according to the fifth embodiment of the present invention, which has a structure corresponding to the above-described second embodiment.
In the one-sided reference color printer, one of the first and second guide members 53a and 53b of the guide mechanism 50, for example, the second guide member 53b, is positioned within the side edge portion of the paper 8 to be fed. Fixedly arranged at a position that guides and holds one side edge that serves as a reference for alignment,
Only the first guide member 53a is provided so as to be movable along the direction in which it comes in contact with and separates from the second guide member.

The structure, control method, and other structures for moving the first guide member 53a are the same as those of the second embodiment, and the same parts are designated by the same reference numerals and will not be described in detail. The description is omitted.

Also in the fifth embodiment configured as described above, the paper can be reliably and stably transported without using the conventional transport belt, and the same operation as in the second embodiment is performed. The effect can be obtained.

FIG. 18 shows the structure of a one-sided reference color printer according to a sixth embodiment of the present invention, which has a structure corresponding to the above-described third and fourth embodiments. . In the one-sided reference color printer, the first and second guide members 53a and 53b of the guide mechanism 50 are provided.
One of the two, for example, the second guide member 53b,
Of the side edges of the sheet 8 to be fed, it is fixedly arranged at a position for guiding and holding one side edge serving as a reference for alignment, and only the first guide member 53a is the second guide member. It is provided so as to be movable in the direction of approaching and separating.

The structure, control method, and other structures for moving the first guide member 53a are the same as those of the third and fourth embodiments, and the same parts are designated by the same reference numerals. Detailed description is omitted.

Also in the fifth embodiment having such a configuration, it is possible to reliably and stably convey the standard size paper and the manually fed paper without using the conventional conveyor belt. The same effects as those of the third and fourth embodiments can be obtained.

The present invention is not limited to the above-described embodiments, but can be variously modified within the scope of the present invention. For example, the present invention is not limited to color printers, but can be applied to other image forming apparatuses such as color copying machines.

Further, according to the present invention, the transfer means is not limited to the transfer roller, and a transfer charger or the like can be used.

[0122]

As described in detail above, according to the present invention, it is not necessary to use a conventional conveyor belt, the transfer material can be stably conveyed, and the winding of the transfer material around the image carrier can be prevented. Therefore, it is possible to provide the image forming apparatus capable of reducing the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a sectional view of a color printer according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a photosensitive drum and a guide mechanism of the color printer.

FIG. 3 is a front view showing a photosensitive drum and a transfer roller of the color printer.

FIG. 4 is a sectional view of a color printer according to a second embodiment of the invention.

FIG. 5 is a perspective view showing a photosensitive drum and a guide mechanism of the color printer according to the second embodiment.

FIG. 6 is a flowchart showing the operation of the color printer according to the second embodiment.

FIG. 7 is a sectional view of a color printer according to a third embodiment of the invention.

FIG. 8 is a perspective view showing a photosensitive drum and a guide mechanism of the color printer according to the third embodiment.

FIG. 9 is a flowchart showing the operation of the color printer according to the third embodiment.

FIG. 10 is a flowchart showing a modification of the color printer according to the third embodiment.

FIG. 11 is a sectional view of a color printer according to a fourth embodiment of the invention.

FIG. 12 is a cross-sectional view showing an image forming unit and a switching mechanism in an operating position of the color printer according to the fourth embodiment.

FIG. 13 is a front view showing the switching mechanism in an operating position together with a photosensitive drum and a transfer roller.

FIG. 14 is a cross-sectional view showing an image forming unit and a switching mechanism in a non-operating position of the color printer according to the fourth embodiment.

FIG. 15 is a front view showing the switching mechanism in a non-operating position together with a photosensitive drum and a transfer roller.

FIG. 16 is a flowchart showing the operation of the color printer according to the fourth embodiment.

FIG. 17 is a perspective view showing a photosensitive drum and a guide mechanism of a color printer according to a fifth embodiment of the present invention.

FIG. 18 is a perspective view showing a photosensitive drum and a guide mechanism of a color printer according to a sixth embodiment of the invention.

[Explanation of symbols]

 1Y, 1M, 1C, 1BK ... Photosensitive drum 5Y, 5M, 5C, 5BK ... Transfer roller 8 ... Paper 10Y, 10M, 10C, 10BK ... Image forming unit 20 ... Paper feeding mechanism 26 ... Registration roller pair 50 ... Guide mechanism 51 ... Paper feed guide 52 ... Paper discharge guide 53 ... Back side holding guide 53a, 53b ... Guide member 54 ... Back side holding guide 55a, 55b ... Rack 56a, 56b ... Control motor 57 ... Motor control section 58 ... Manual insertion guide 60 ... Operation panel 61 Main control unit 65 Optical sensor 68 Switching mechanism 70Y, 70M, 70C, 70BK Eccentric cam 72Y, 72M, 72C, 72BK Guide roller 74Y, 74M, 74C, 74BK Solenoid

Claims (12)

[Claims] 1. A plurality of image bearing members provided with their central axes parallel to each other, and a plurality of image forming means for forming an image during the image bearing period, each of which is provided facing the image bearing member. A plurality of transfer means for transferring an image formed on the image carrier to a transfer material, a transport means for transporting the transfer material between the image carrier and the transfer means, and a transport direction of the transfer material A fixed back side guide that is disposed along the transfer material and that guides and holds the non-image transfer surface side of the transfer material, and extends in the transport direction of the transfer material in contact with the plurality of image bearing materials. An image forming apparatus comprising: a front surface side guide that guides and holds a non-image forming area on the image transfer surface side of a transfer material. 2. A plurality of image bearing members provided with their central axes parallel to each other, a plurality of image forming means for forming images during the image bearing period, and a plurality of image bearing members facing the image bearing members, respectively. A plurality of transfer means for transferring the image formed on the image carrier to a transfer material; a transport means for transporting the transfer material between the image carrier and the transfer means; and a transport of the transfer material. A fixed backside guide that is arranged along the direction and guides and holds the non-image transfer surface side of the transfer material, and extends along the transfer material conveyance direction in contact with the plurality of image bearing materials. And a front side guide that is provided so as to be movable in a direction orthogonal to the transport direction and that guides and holds the non-image forming area on the image transfer surface side of the transfer material, and a moving unit that moves the front side guide. , The above transfer material Input means for inputting a size in a direction orthogonal to the conveying direction, and control means for moving the front side guide by the moving means in accordance with the size detected by the input means. Image forming apparatus. 3. A plurality of image bearing members provided with their central axes parallel to each other, a plurality of image forming means for forming images during the image bearing period, and a plurality of image bearing members facing the image bearing members, respectively. A plurality of transfer means for transferring the image formed on the image carrier to a transfer material; a transport means for transporting the transfer material between the image carrier and the transfer means; and a transport of the transfer material. A fixed backside guide that is arranged along the direction and guides and holds the non-image transfer surface side of the transfer material, and extends along the transfer material conveyance direction in contact with the plurality of image bearing materials. And a front side guide that is provided so as to be movable in a direction orthogonal to the transport direction and that guides and holds the non-image forming area on the image transfer surface side of the transfer material, and a moving unit that moves the front side guide. , Any size transfer Manual feeding means for feeding the copying material to the conveying means, detecting means for detecting the size of the transfer material fed by the manual feeding means in the direction orthogonal to the conveying direction, and the size detected by the detecting means. Accordingly, the image forming apparatus includes: a control unit that moves the front surface side guide by the moving unit. 4. A plurality of image carriers provided with their central axes parallel to each other, a plurality of image forming means for forming images during the image bearing period, respectively, and a plurality of image forming means provided so as to face the image carriers. A plurality of transfer means for transferring the image formed on the image carrier to a transfer material; a transport means for transporting the transfer material between the image carrier and the transfer means; and a transport of the transfer material. A fixed backside guide that is arranged along the direction and guides and holds the non-image transfer surface side of the transfer material, and extends along the transfer material conveyance direction in contact with the plurality of image bearing materials. And a front side guide that is provided so as to be movable in a direction orthogonal to the transport direction and that guides and holds the non-image forming area on the image transfer surface side of the transfer material, and a moving unit that moves the front side guide. Acquires multiple transfer materials An accommodating portion that contains the transfer material, a supply means that supplies the transfer material from the accommodating portion to the conveying means one by one, and an input means that inputs the size of the transfer material accommodated in the accommodating portion in a direction orthogonal to the conveying direction A manual feeding means for selectively feeding a transfer material of an arbitrary size to the conveying means; a detecting means for detecting the size of the transfer material supplied by the manual feeding means in a direction orthogonal to the conveying direction; When the front side guide is moved by the moving means according to the size input by the input means or the size detected by the detecting means, and the transfer material is supplied by the manual feeding means, the input means is used. Control means for moving the front side guide by the moving means in accordance with the size detected by the detecting means in preference to the size input by An image forming apparatus comprising: a step; 5. A plurality of image bearing members provided with their central axes parallel to each other, a plurality of image forming units for forming images on the image bearing member, and operating positions for contacting the image bearing members, respectively. A plurality of transfer means for moving the image formed on the image carrier to a transfer material at the operating position, the transfer means being provided so as to be movable between the image carrier and a non-operating position separated from the image carrier. Switching means for switching between an operating position and a non-operating position, a transporting means for transporting the transfer material between each of the image carriers and the transfer means, and a transfer means disposed along the transporting direction of the transfer material. A fixed back side guide that guides and holds the non-image transfer surface side of the material, and a direction that is in contact with the plurality of image bearing materials and extends along the transfer direction of the transfer material, and that is orthogonal to the transfer direction. Movably provided A front surface side guide for guiding and holding a non-image forming area on the image transfer surface side of the transfer material, a moving means for moving the front surface side guide, and a conveying direction of the transfer material conveyed by the conveying means. Detecting means for detecting the size in the direction orthogonal to the, and moving the front side guide by the moving means according to the size detected by the detecting means,
When moving the front side guide by the moving means,
An image forming apparatus comprising: a control unit that switches the transfer unit to a non-operating position by the switching unit. 6. The front side guides are in contact with the plurality of image bearing materials, extend along the transfer direction of the transfer material, and both side edge portions extend along the transfer direction of the transfer material. Slidable strip-shaped first and second guide members that can be respectively contacted with the first and second guide members, the first and second guide members being movably provided in a direction orthogonal to the transport direction, and the moving means. 6. The first and second guide members are moved in mutually opposite directions to change the distance between the first and second guide members, according to any one of claims 2 to 5. The image forming apparatus according to item 1. 7. The moving means comprises a pair of first racks extending from both ends of the first guide member toward the second guide member along the carrying direction, and a pair of first racks in the carrying direction. From both ends of the second guide member along the first guide member.
Pair of second racks that extend toward the guide member of the first rack and that face the first rack, gears that mesh with the first and second racks that face each other, and a drive that drives the gears. The image forming apparatus according to claim 6, further comprising a motor. 8. The front side guides are in contact with the plurality of image bearing materials, extend along the transfer direction of the transfer material, and both side edge portions extend along the transfer direction of the transfer material. Slidable strip-shaped first and second guide members respectively contactable with the first guide member, the first guide member is movably provided in a direction orthogonal to the transport direction, and the moving means is Move the first guide member,
The image forming apparatus according to claim 2, wherein a distance between the first and second guide members is changed. 9. The moving means comprises a pair of racks extending from both ends of the first guide member toward the second guide member along the carrying direction, and the first rack respectively.
9. The image forming apparatus according to claim 8, further comprising: a gear meshed with the rack of 1. and a drive motor that drives each of the gears. 10. The first and second guide members are made of a flexible material having a width of about 10 mm or less and a thickness of about 0.1 mm or less. The image forming apparatus according to claim 1. 11. The back surface side guide has a plurality of back surface side guide members arranged between adjacent transfer means, and the back surface side guide member is formed of a conductive material and has a constant potential. The image forming apparatus according to claim 1, wherein the image forming apparatus is held in the image forming apparatus. 12. The image forming apparatus according to claim 1, wherein each of the transfer means includes a transfer roller that is in contact with the corresponding image carrier.