JPH01288881A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an image of high quality free from creases of a transfer material or the like by providing a fixing device, which consists of a pair of rotating bodies below a nip part between a photosensitive drum and a rotating body for transfer, in the tangential direction of the nip part at the time of passage of the sheet-shaped transfer body across this nip part. CONSTITUTION:A transfer material 18 is fed from a paper supply part and enters into a nip part B between photosensitive drum 1 and a transfer roll 10, and the toner image on the drum 1 is transferred to this transfer material 18. The transfer material 18 is guided by a carrying guide 12 and a fixing device entrance guide 17 and enters into a nip part F of the fixing device consisting of rotating bodies 15 and 16, and the transferred image is fixed. At this time, rotating bodies 15 and 16 are arranged in the tangential direction of a line G of the drum surface part in a downstream end position A in the face movement direction of the nip part B. Thus, an image of high quality free from deviation, scratch, dirt, and creases is obtained.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an image forming apparatus.

More specifically, a transferable image of target image information is formed and carried by an image forming process means on the surface of a first image carrier which is driven to move, and a sheet serving as a second image carrier is formed on the surface of the image carrier. feeding a shaped transfer material and sequentially transferring the transferable image on the first image carrier surface side by an image transfer means;
The present invention relates to an image forming apparatus that introduces a second image carrier onto which an image has been transferred into a fixing means, fixes the image, and outputs the image.

(Prior Art) Specific examples of image forming apparatuses using the above method include copying machines and printers that utilize transfer-based electrophotography, electrostatic recording, magnetic recording, and other known appropriate transfer-based image forming methods. - Examples include microfilm reader printers and display devices.

Generally, an electrophotographic photoreceptor, an electrostatic recording dielectric material, a magnetic recording magnetic material, etc. as a first image carrier is configured in the form of a drum or belt that is rotationally driven or rotatably driven at a predetermined circumferential speed. Then, a latent image such as an electrostatic latent image, a potential latent image, or a magnetic latent image corresponding to the target image information is formed on the drum surface or belt surface using an image forming process device, and the latent image is converted into a transferable image using a developer. Visualize as. Then, a sheet-like transfer material (generally a sheet material mainly made of paper) as a second image carrier is fed to the drum surface or belt surface, and the image transfer means transfers the image to the drum surface or belt surface. The developed image on the side is sequentially transferred to the side of the transfer material, and the transfer material that has received the image transfer is fixed with the image by a fixing means and is discharged from the apparatus as an image-formed product. The main drum surface or belt surface is cleaned by a cleaning means and is repeatedly used for image formation.

A transfer charger (corona discharger) is generally used as the image transfer means.

The fixing means generally includes a pair of opposing rotating bodies, such as a pair of heat fixing rollers, a pair of heat-pressure fixing rollers, a pair of pressure fixing rollers, etc., and a second image carrier that receives the image transfer at the nip portion of the pair of rotating bodies. A fixing device is used in which a barrel of transfer material is introduced and passed through a nip portion to fix the image.

Image transfer using a transfer charger involves feeding a transfer material to the surface of a first image carrier carrying a toner image, which is a transferable image, and applying corona discharge to the transfer material to change the toner image on the image carrier surface to toner polarity. By applying a charge of opposite polarity, the toner image on the side of the image carrier is transferred and adsorbed (transferred) to the side of the transfer material facing the image carrier by electrostatic attraction.
It has the advantage of a simple configuration and relatively stable transfer performance.

However, on the other hand, the excessive backside charge applied to the backside of the transfer material may cause the developer to scatter around the transferred characters. During transfer, the transfer material is in contact with the image carrier surface only by electrostatic force, so when the trailing edge of the transfer material slips out of the registration rollers that convey the transfer material to the transfer section in a timely manner, or when the fixing device There is a drawback that image displacement (transfer displacement) may occur due to the shock of the leading edge of the transfer material entering between the roller pair.

In addition, when using a transfer charger using corona discharge, the voltage applied to the corona wire needs to be a high voltage of 3 to 5 kilovolts in order to stabilize the discharge and provide sufficient back charge to the transfer material. There is. This increases the cost of the power supply, and in the case of small printers, this becomes a factor that cannot be ignored as a cost pressure factor. Also, as corona discharge occurs, ozone is generated.

As another image transfer means that does not have the above-mentioned problems, a transfer rotary member that faces the surface of the first image carrier and rotates or rotates in the forward direction in the direction of movement of the surface of the first image carrier is disposed. established,
A transfer material, which is a second image carrier, supplied to the surface of the first image forming body on which a transferable image is formed and carried is pressed with a predetermined pressing force by the transfer rotary body. Preferably, the transfer rotary body is made of an elastic material. Image transfer is performed by applying a transfer bias (including grounding) to a conductive material.

FIG. 8 shows a schematic configuration of an example of a laser beam printer (LBP) using electrophotography as an image forming apparatus as described above. This is a drum-shaped electrophotographic photoreceptor (hereinafter referred to as a tram) that is rotated around a support shaft 1a at a predetermined circumferential speed in the clockwise direction indicated by the arrow.

The circumferential surface of the rotating drum 1 is charged in a positive or negative - manner by a primary charger 2, and then outputted from a laser beam scanner 4 by a computer, word processor, or computer (not shown).
An electrostatic latent image of target image information is formed by scanning exposure with a laser beam 3 modulated in accordance with time-series electrical pixel signals manually input from an image reading device or the like. 5
is a reflecting mirror that deflects the output laser beam 3 from the scanner 4 to the scanning exposure position of the drum 1. The latent image formed on the surface of the drum is visualized by a developing device 6 as a transferable developer image (hereinafter referred to as a toner image).

T indicates the developer in the developing device.

On the other hand, a sheet-like transfer material 18 as a second image carrier is transferred from the paper feed roller 8 in the paper feed cassette 7 of the paper feed section to one sheet.
The sheet is unrolled, its leading edge is temporarily stopped by a pair of registration rollers 9 which are in a stopped state at that time, and then the sheet is rotated at a predetermined timing synchronized with the rotation angle of the drum 1. Tram 1 by registration roller pair 9
and the transfer roller 10 as a rotating body for transfer (
It is fed to the transfer section) B at the same speed as the peripheral rotational speed of the tram 1. 20 indicates a transfer material guide.

The transfer roller 10 is a roller made of an elastic/conductive material (for example, a specific resistance of 10' to 10'' Ωcm), and is constantly brought into contact with the surface of the drum, which is the first image carrier, with a predetermined pressing force. Alternatively, it is normally held apart from the surface of the drum, and during transfer, it comes into contact with the surface of the drum with a predetermined pressing force via the feeding transfer material.

Reference numeral 11 denotes a power source for applying a bias voltage to the transfer roller 10, which applies a predetermined voltage (DC voltage, or a superimposed voltage of DC voltage and AC voltage) having a polarity opposite to that of the toner of the toner image formed and carried on the drum 1 surface to the roller 10. Applied against.

The transfer material 18 that has entered the nip B between the drum 1 (transfer material) and the transfer roller 10 undergoes the sequential transfer of toner images on the drum 1 side due to the pressure applied by the transfer roller 10 to the drum 1 surface and the transfer bias, and is then nipped. The sheet passes through the section B, passes over the conveyance guide 12 and the recording guide 17, and is introduced into the abutment nip F between the fixing roller 15 and the pressure roller 16 of the fixing device. The fixing roller 15 is heated to a predetermined image fixing temperature by a built-in heater 19, and a pressure roller 16 is brought into contact with the lower side of the fixing roller 15 as an upper roller with a predetermined pressing force. 15 and 16 are rotating at a predetermined circumferential speed in the direction of the arrow. The transfer material enters the nip between the rollers 15 and 16 with the image side facing upward, and the fixing roller 15 comes into contact with the image side, and the pressure roller 16 comes into contact with the back side and is heated and pressurized, thereby making the toner image permanent. The images are sequentially fixed as a fixed image, passed between the pair of rollers 15 and 16, and are discharged from the apparatus as an image formed product (print).

After the toner image has been transferred to the transfer material, the surface of the drum is cleaned by a cleaning device 13 to remove residual toner, paper dust, and other adhering contaminants, and is further uniformly exposed to light by a static elimination lamp 14 to eliminate static electricity. By doing so, the electrical memory is erased and used for image formation repeatedly.

By employing the transfer rotary body 10 as the image transfer means, the transfer material is held and conveyed between the drum 1 and the transfer rotary body 10 during the image transfer process, so that the transfer material is transferred from the registration roller pair 9. Even if there is a shock when the trailing edge comes off or when the leading edge of the transfer material enters between the pair of rollers 15 and 16 of the fixing device, no image shift occurs at the transfer section.

Compared to the transfer charger type, the output voltage of the bias power supply is actually 115 to 1/10 as low as the voltage needed to perform sufficiently good image transfer, making it possible to reduce device costs and downsize. There is virtually no or very little ozone generation.

(Problems to be Solved by the Invention) However, the image transfer means using the transfer rotating body has the following problems.

That is, the transfer material serving as the second image carrier enters the nip portion, which is the transfer portion, formed by the first image carrier and the transfer rotating body, and receives the image transfer while being held and conveyed by the nip portion. As mentioned above, this is an important factor in preventing image misalignment, but on the other hand, since the transfer material is held between the first image carrier and the transfer rotating body, the transfer material is The feeding direction can be easily determined, and the position of the transfer rotor,
In other words, the fixing device includes a pair of opposing rotating bodies, and the fixing device is of a type in which the transfer material is introduced into the nip portion of the pair of rotating bodies and is caused to pass through the nip portion to fix the image. If the installation position of the fixing device is not appropriate, (1) wrinkles may occur when the transfer material guided from the transfer unit to the fixing device passes through the fixing device, or (2) it may jam without entering the fixing device. (2) The rear end of the transfer material jumps up and hits the rotating body surface of the fixing device, causing an offset of the unfixed toner image on the rotating body surface.

The present invention relates to an image forming apparatus that uses a transfer rotary body as an image transfer means and a fixing device that fixes an image by introducing a transfer material into a nip between a pair of rotary bodies as a fixing means. By properly defining the mutual positional relationship of the fixing units, without causing the inconveniences described in ■ to ■ above,
Therefore, it is an object of the present invention to constantly and stably output image-formed products of high image quality without image deviations, scratches, stains, wrinkles, etc. without any jam troubles.

(Means for Solving the Problems) (A) The present invention is characterized in that a transferable image of target image information is formed and supported on the surface of a first image bearing member that is driven to move in a plane, and that the image is A sheet-like transfer material serving as a second image carrier is fed onto the carrier surface, and the transferable image on the first image carrier surface side is sequentially transferred by the image transfer means to obtain a second image that has undergone image transfer. This is an image forming apparatus of a type in which a carrier is introduced into a fixing means to fix an image and output the image. It is a transfer rotary body that rotates or rotates in the forward direction and presses the second image carrier against the first image carrier with a predetermined pressing force, and the image fixing means described above has a pair of opposing rotary bodies. A fixing device that fixes an image by introducing a second image carrier into a nip portion of the pair of rotating bodies and passing through the nip portion, the nip formed by the first image carrier and the transfer rotating body. The image forming apparatus is characterized in that the fixing device is disposed in a tangential direction of the first image carrier surface portion at a downstream end position in a surface movement direction of the image carrier surface portion.

(B) The present invention also provides an image forming apparatus according to the invention set forth in item (1) above, in which the tangent line of the first image carrier is a second image carrier inlet guide of the fixing device, one of the pair of opposing rotating bodies. The image forming apparatus is characterized in that a fixing device is disposed in a relationship that intersects at least a portion of the image forming apparatus.

(C) Furthermore, the present invention provides an image forming apparatus according to the invention set forth in item (1) above, in which the head tangent of the first image carrier is connected to one of the pair of opposing rotating bodies of the fixing device. The image forming apparatus is characterized in that a fixing device is disposed in a relationship passing between the center of the image forming apparatus and the upstream end position of the nip portion of the pair of opposing rotating bodies in the plane movement direction.

(Function) First, wrinkles in the transfer material in item (■), which are easy to see when the mutual positional relationship between the transfer unit and the fixing device described in the above (problems to be solved by the invention) is inappropriate, and in item 0. transfer material jam,
The reason for the occurrence of the offset of the unfixed image with respect to the surface of the rotating body of the fixing device in item (2) will be explained.

In FIG. 9, P... Rotating drum 1 as a first image forming body
Center Q...Center B of the elastic transfer roller 10 as a rotating body for transfer that is brought into contact with the drum 1 with a predetermined pressing force...The nip formed between the tram 1 and the transfer roller O Part A... Downstream end position G in the surface movement direction of nip part B.
...Tangential line of the drum surface at position A. This is referred to as the first tangent.

R... Center S of the fixing roller 5 of the fixing device...
...Center F of the pressure roller 6 of the fixing device...Nip portion C formed between the fixing roller 15 and pressure roller 16...Upstream end position H of the nip portion F in the surface movement direction・
...Widthwise center point position D of nip portion F...
・1/4 peripheral surface position E on the upstream side in the roller rotational direction from position H for the fixing roller 15... Indicates a 1/4 peripheral surface position on the upstream side in the roller rotational direction from position H on the pressure roller 16 There is.

Reference numeral 18 denotes a transfer material fed from the paper feed section to the transfer section, and the transfer material 18 enters the nip section B between the tram 1 and the transfer roller 10, which is the transfer section, and passes through the nip section.
The transfer guide 12 sequentially receives the transfer of the toner image on the side.
Guided by the fixing unit entrance guide 17, the transfer image enters the nip F between the fixing roller 15 and the pressure roller 16, and as it passes through, the transferred image is fixed.

The leading edge side portion of the transfer material 18 that has passed through the nip B between the transfer material drum 1 and the transfer roller 10 is sent out at position A along the first tangent line G, and thereafter is fed out by its own weight. As a result of this action, it gradually deflects downward and moves away from the first tangent line G below. If the entrance guide 17 of the fixing device and the entire DCE portion of the roller pair 15 and 16 are located above the first tangent line G, that is, on the same side as the tram 1, the transfer material 18 The feeding direction of the transfer material is forcibly bent in the opposite direction by the guides 12 and 17 with respect to the above deflection direction, and the transfer material is guided to the nip portion F of the roller pair 15 and 16, which causes unnecessary stress on the transfer material. The transfer material 18 guided from the transfer section to the fixing device in order to
It has been found that wrinkles are more likely to occur when the image passes through the fixing devices 15 and 16.

Also, contrary to the case of FIG. 9 above, as shown in FIG.
The artificial guide 17 of the fixing device is located below the tangent G of
- If the E part is located, the drum 1 and transfer roller 10
A distance is required for the transfer member that has passed through the nip portion B with the transfer member to descend to the conveyance guide 12 due to its own weight, and therefore the apparatus cannot be made smaller. Furthermore, since the direction of the population guide 17 and the direction of the transfer material sent out from the nip portion B between the drum 1 and the transfer roller 10 are significantly different, a loop is formed in the transfer material 18 as shown in 18, and the trailing edge of the transfer material is drum 1
The loop return movement at the time when the toner passes through the nip B between the transfer roller 10 and the transfer roller 10 tends to cause disturbances in the unfixed toner image on the surface of the transfer material. Then, the human logite 17 and the fixing roller 1
5 and the pressure roller 16 at the upstream end position C in the surface movement direction of the nip portion F, the direction of the contact surface differs greatly, stress accumulates on the transfer material here, and the rear end side of the transfer material springs up significantly. This hits the surface of the fixing roller 15 and causes an offset of the unfixed toner image on the surface of the roller.

Furthermore, the leading edge of the transfer material that passed through the nip B between the transfer material tram 1 and the transfer roller 10 and was guided to the fixing device hit a portion other than the DCE portion of the roller pair 15 and 16 of the fixing device. It has been found that when the transfer material 18 is sent in a direction other than the direction toward the nip portion F of the pair of rollers 15 and 16 of the fixing device, it does not enter the nip portion F and jams are likely to occur.

Therefore, the present invention is based on the above-mentioned matters.
The first tangent line (G) as defined above for the inventive device in Section A).
The fixing devices (15 and 16) are arranged in the same direction, so that the transfer material (18) exiting the transfer section (B) can be smoothly transferred to the nip of the opposing rotating body of the fixing device without accumulating stress. (F'), and the above-described problems such as wrinkles in the transfer material, occurrence of transfer material jams, and offset of the unfixed toner image with respect to the fixing device roller are solved.

Further, as in the device according to the invention described in item (B) above, the first tangent line (G) is the transfer material entrance guide (17) of the fixing device or one of the pair of opposing rotating bodies (15, 16) (fixing roller or pressure roller).
By arranging the fixing device in a relationship that intersects with at least a portion of the transfer section (B) and the fixing device (15, 16), the mutual positional relationship between the transfer section (B) and the fixing device (15, 16) is further optimized and more preferable. Get results.

Furthermore, as in the inventive device of item (C) above, the first tangent line (
G) is the center (R or S) of one of the rotating bodies (fixing roller or pressure roller) of the pair of opposed rotating bodies (15, 16) of the fixing unit and the nip part of the pair of rotating bodies (15, 16). By arranging the fixing device in a relationship that passes between the upstream end position (C) in the plane movement direction of (F), the transfer material (
18), regardless of the type of transfer material, and move it almost straight toward the fixing device to reach the nip portion F of the opposing rotating bodies (15 and 16) of the fixing device.
In this case, it is also possible to omit the transfer material population guide (17) and conveyance guide (12), and it is possible to always smoothly introduce the transfer material from the transfer material to the fixing device to prevent wrinkles and jams. - It becomes possible to execute without problems such as offset.

(Example) Example 1 (Fig. 1) Fig. 1 shows a nip portion B formed by a rotating drum 1 as a first image carrier and a transfer roller 10 as a transfer rotating body according to the present invention. A relationship example is shown in which the fixing devices 15 and 16 are arranged in the direction of the tangent G to the drum surface at the upstream end position A in the surface movement direction.

The same members and portions as those shown in FIG. 9 are given the same reference numerals, and repeated explanations will be omitted.

An OPC photosensitive drum with an outer diameter of 30 mm is used as the tram 1, and a hardness of 25° (AS) is used as the transfer roller 10.
KER- (: ) - Using a roller with an outer diameter of 20 mm, press the roller 10 against the tram 1 so that the width of the nip portion B is 2 mm. In this case, the transfer roller 10 is at its center Q
θ1=13° in the vertical direction from the center P of tram 1
, and are positioned shifted upstream in the rotational direction of the tram 1.

The fixing roller 15 of the fixing unit is a roller with an outer diameter of 30 mm whose outer layer is coated with PFA, and the pressure roller 16 is a roller with a hardness of 5.
2° (JIS-A) - Using a roller with an outer diameter of 30 mm whose surface layer was coated with silicone rubber, pressure was applied to the pressure roller 16 so that the width of the nip portion F was 3.5 non.

In this case, the pressure roller 16 has its center S aligned with the fixing roller 15.
The fixing roller 15 is positioned downstream of the center R of the fixing roller 15 in the rotational direction of the fixing roller 15 by θ2=6° with respect to the vertical direction.

The distance between the A position and the C position is 132 mm, and the distance between the center P of the drum 1 and the center R of the fixing roller 16 in the vertical direction is 20+ nm.
, 130mm apart horizontally, drum tangent G at position A
The relational configuration is such that the fixing devices 15 and 16 are located in the direction of.

Then, when the toner image formed and carried on the drum 1 is transferred to a transfer material by the transfer roller 10, and the image is fixed by the fixing devices 15 and 16 and output, the output transfer material wrinkles and jams occur. The number of occurrences decreased, and when the size of the transfer material used was limited to a length longer than the 6-plate horizontal feed, when the transfer material entered the nip F of the pair of fuser rollers 15 and 16, the transfer material moved between the transfer roller 10 and the drum. No image blurring occurred because the image was sandwiched between the two images.

In particular, it is more effective to arrange the fuser at a position where the first tangent line G intersects with the entrance guide 17 of the fuser or the DCE peripheral surface area of the roller pair 15 and 16, so that the transfer material is always conveyed smoothly. , and wrinkles and jams were significantly reduced.

Example 2 (Figures 2 and 3) This example (Figure 2) is obtained by adding the following conditions to Example 1 (Figure 1). That is, the drum 1 and the transfer roller 10
The first tangent G of the drum 1 at the A position of the nip B of
However, the fixing units 15 and 16 are arranged in a relationship that passes between the center R of the fixing roller 15 and a position C in the nip F between the fixing roller 15 and the pressure roller 16.

Experiments revealed that the free length of the transfer material 18 (paper) is 1 ([llll11
) and the amount of deflection W (mm) was found to be as shown in the graph in Figure 3. This graph shows the amount of deflection due to its own weight when one end of the transfer material is fixed.

From this graph, it can be seen that if the free length is up to 50 ml11, the transferred transfer material will move straight due to its own strain strength, regardless of the type (basis weight g/m2).

In recent years, image forming apparatuses have become more compact, and if the distance from the A position to the fixing roller 15 can be reduced to 50 mm or less, miniaturization can be promoted. In that case, in FIG. 2, there is a first tangent line G above the line T connecting position A and the center R of the fixing roller.
If so, when the transfer material 18 comes into contact with the surface of the fixing roller 15, if the transfer material has a large basis weight, the transfer material will be sent to the upper side of the fixing roller 15, and a jam may occur. Therefore, it is preferable that the first tangent line G is below the line T. Furthermore, conventionally, in order to prevent wrinkles, the leading edge of the transfer material was first brought into contact with the fixing roller 15, which is a rigid roller. Therefore, it is preferable that the first tangent line G exists above the line U including the A position and the C position.

For the above reasons, it is clear that it is better for the first tangent G to pass between the C position and the R position. In particular, when the distance between position A and position C is 50+nm or less, it is possible to send the transfer material to a fixed position regardless of the type of transfer material, as shown in the graph in Figure 3, so the population guide ( 17) and the conveyance guide (12) can be omitted, reducing costs.

Embodiment 3 (Fig. 4) In this example, the first tangent line G is located at the center S of the pressure roller 16 of the fixing device, contrary to the case of Embodiment 2 (Fig. 2).
The fixing devices 15 and 16 are arranged so as to pass between the C position and the C position.

A heating heater (not shown) inside the fixing roller 15 has a heating temperature of 750.
In a high-speed machine exceeding W, if the transfer material is directly conveyed and applied to the fixing roller 15 as in Example 2, the transfer material is likely to shift at the leading edge, resulting in double images at the leading edge. Further, it is preferable to provide a distance so that the heat of the fixing device is not transmitted to the drum 1, and the distance between the A position and the C position is set to 50 mm or more. In such a case, - bend the anti-transfer material and then move the fixing roller 1 along the population guide 18.
It has been conventionally known that it is preferable to direct the material to the nip portion F by applying the material to the nip portion F.

In this case as well, the transfer material will be deflected as shown in Figure 10, but in order to suppress this deflection and send the transfer material smoothly, it is necessary to move the transfer material between the C position and the S position as in this example. It is sufficient that the tangent line of the tram 1 at the A position, that is, the first tangent line G passes through.

Note that Example 1 (FIG. 1) also satisfies this condition, giving good results with less occurrence of jams and wrinkles in the transfer material and no image deviation.

Embodiment 4 (Fig. 5) This example is a modification of Embodiment 2 (Fig. 2), in which the transfer material is conveyed obliquely upward toward the fixing device from the time of transfer. It is.

Such an arrangement becomes essential for downsizing the device. This is because, in order to prevent heat from the fixing device from being transferred to the tram 1, it is better to place the fixing device at the top. This is because it has the advantage of being able to exhaust air warmed by the fuser through a chimney effect.

In the experiment, an OPC drum with an outer diameter of 30 mm was used as the tram 1, and a hardness of 250 (85 KER-c) was used as the transfer roller.
), a conductive rubber roller with an outer diameter of 16 mm was used, and the width of the nip B with the tram 1 was set to 2 mm. Also, fixing roller 1
5. Outer diameter 20mm with PFA tube covered on the outer layer
The pressure roller 16 has a hardness of 30° (JI
S-A), a silicone rubber roller with an outer diameter of 16 mm was used, and the width of the nip portion F between both rollers 15 and 16 was set to 2 mm. A heater 1 for heating is provided inside the fixing roller 15.
9, a 390W (115V) halogen heater was installed.

Furthermore, the distance between the A position and the C position is set to 40 mm, and the line AC
When configured so that the angle θ3 made with the vertical direction is 320, the heat from the fixing device is not transmitted to the drum 1,
Therefore, it was possible to prevent the toner from adhering to the drum, and to achieve good transfer material conveyance, thereby reducing jams and wrinkles of the transfer material.

Embodiment 5 (FIG. 6) This embodiment is a further modification of the embodiment 2 (FIG. 2), in which the transfer material is conveyed from above.

By transporting the transfer material 18 on the upper side of the tram 1, the developing device and cleaner can be placed at the bottom of the tram 1, which has the advantage that the problem of toner staining on the transport path and the transfer material due to toner scattering does not occur. However, since the image surface of the transfer material that has received the toner image transfer is on the lower side, if the AC interval is too long, the transfer material will bend downward. It was necessary to either transport it or transport it. However, if the AC distance is set to 50 mm or less by applying Example 2, the transfer material can be conveyed in a straight line by utilizing its rigidity (strength). This eliminates the need for charging belts and suction fans. In this case as well, it goes without saying that the tangent line G of the tram 1 at position A only needs to pass between the center R of the fixing roller and the upstream end C of the nip portion F.

In the experiment, an OPC drum with an outer diameter of 30 ooo was used as the drum 1, and an OPC drum with a hardness of 25° (ASKE) was used as the transfer roller 10.
R-C), a 16 mm conductive rubber roller is used so that the tangent line G of the drum 1 at position A is horizontal, the distance between AC is 40 mm, and a roller with an outer diameter of 20 mm covered with a PFA tube as the fixing roller 15; A silicone rubber roller with a hardness of 30° (JIS-A) and an outer diameter of 16IIIO was used as the pressure roller, and the tangent line G was placed between the center R of the fixing roller 15 and the upstream end C of the nip portion F. It was possible to obtain good transfer material conveyance without jams or wrinkles, and there was no image shift.

Example 6 (FIG. 7) Also in the case of the configuration like Example 5 described above, the fixing roller 1
In a high-speed machine in which the output of the heater 19 of No. 5 exceeds 750 W, it is desirable to provide a sufficient interval so that the heat of the fixing device does not affect the drum 1, as shown in FIG. In this case, if J- is the range in which the attractive force of the suction fan 22 moves, it is preferable that the interval between AJ is AJ<50 mm, and that AJ coincides with the drum tangent G at position A.

Also, the interval between KC is also KC<50111111, and K
It is preferable that the tangent line of the conveyor belt 23 in is made to pass between the center R of the fixing roller 15 and the downstream end C of the nip portion F.

Although the above six embodiments have been described, a pressure fixing device may be used as the fixing device. Only point C comes, and the other configurations and logic can be used as they are in the previous embodiment. That is, the present invention is an effective technique even when the fixing device used is a pressure fixing device.

The drum as the image carrier of the writing brush 1 may be in the form of a rotating belt, and the transfer roller as the rotating body for transfer may also be in the form of a rotating belt.
Even in these cases, the configuration and logic of the present invention can be used as is.

(Effects of the Invention) As described above, the present invention uses a rotating belt for transfer (a rotating transfer roller, a rotating belt, etc.) as an image transfer means, and a pair of rotating bodies (a pair of rotating rollers, a rotating belt, etc.) as a fixing means. equal)
For image forming apparatuses that use a fixing device that fixes images by introducing a transfer material into the nip section, the mutual positional relationship between the transfer section and the fixing device has been defined to be an appropriate relationship, thereby preventing image misalignment, rubbing, and It is possible to consistently and smoothly output high-quality image-formed products without stains, wrinkles, etc. without jamming or offset troubles.

In addition, even when the transfer material is conveyed from the top side or when the fixing device is placed above the transfer section, the conveyance of the transfer material can be stabilized, jams and wrinkles can be prevented, and the image can be maintained within the device. It has become possible to prevent it from rubbing and causing disturbances.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the main part of the first embodiment, and Fig. 2 is a schematic diagram of the main part of the first embodiment.
Figure 3 shows the relationship between the free length of various transfer materials (transfer papers with different weights) and the amount of deflection due to their own weight, and Figures 4 to 7 show the relationship between the third to sixth embodiments, respectively. Figure 8 is a schematic diagram of the configuration of an example of an image forming apparatus (transfer-type electrophotographic LBP), and Figures 9 and 10 are configuration examples that make it easy to see image misalignment, wrinkles, jams, etc. on the transfer material. This is a schematic diagram. 1 is a rotating drum type electrophotographic photoreceptor as a first image carrier, 10 is a transfer roller made of an elastic/conductive material as a rotating body for transfer, 18 is a sheet-like transfer material as a second image carrier, 15 and 16 are the fixing roller and pressure roller of the fixing device. Patent applicant: Canon Co., Ltd. No. 7

Claims (3)

[Claims] (1) A transferable image of target image information is formed and carried by an image forming process means on the surface of a first image carrier that is driven to move in plane, and a sheet-like transfer is performed on the surface of the image carrier as a second image carrier. The material is fed and the image transfer means sequentially transfers the transferable image on the side of the first image carrier, and the second image carrier that has received the image transfer is introduced into the fixing means to fix the image and output. The image forming apparatus is a type of image forming apparatus in which the image transfer means faces the surface of the first image carrier and rotates or rotates in a forward direction in a surface movement direction of the image carrier, and transfers the image to the second image carrier. The image fixing means includes a pair of opposed rotating bodies, and the second image carrying body is placed in the nip portion of the pair of rotating bodies. is a fixing device that fixes an image by introducing the image into the nip and passing through the nip, and the first image carrier face portion at the downstream end position in the plane movement direction of the nip formed by the first image carrier and the transfer rotary body. An image forming apparatus characterized in that the fixing device is arranged in a tangential direction of the image forming apparatus. (2) The fixing device is arranged in such a manner that the tangent to the first image carrier intersects with at least a portion of the second image carrier entrance guide of the fixing device and one of a pair of opposing rotating bodies. The image forming apparatus according to claim 1. (3) The tangent to the first image carrier extends between the center of one of the pair of opposing rotating bodies of the fixing device and the upstream end position of the nip portion of the pair of opposing rotating bodies in the plane movement direction. The image forming apparatus according to claim 1, further comprising a fixing device disposed in a passing relationship.