JPH02306279A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE:To miniaturize a recorder and to stabilize the posture of a carried sheet by setting a distance between a toner transfer part and a fixing part so that the trailing edge of a recording sheet does not pass between a photosensitive body and the transfer part when the fixing part does not hold the leading edge of the recording sheet and providing a paper jumping-up preventing guide on the inlet of the toner fixing part. CONSTITUTION:An image is transferred between the photosensitive body 7 and a toner transfer means 8, and fixing rollers 1 and 2 pinch and eject the sheet. At this time, the distance between the transfer part 8 and the fixing parts 1 and 2 is shortened to the extent that the trailing edge of the recording sheet 6 does not pass between the photosensitive body 8 and the toner transfer part 8 all the time when the fixing part does not hold the leading edge of the recording sheet 6, thereby miniaturizing the recorder. The guide 4 preventing the jump-up of the recording sheet 6 is provided on the inlet of the toner fixing parts 1 and 2, and a central, projecting part is disposed closer to the side of a heat roller 1 than the advancing angle of the nip of a pressure roller 2 and pushes up the sheet 6, which is bent downward and deformed along the surface of the guide 4. Consequently, the jump-up of the sheet 6 is prevented. Therefore, the posture of the carried sheet is stabilized, and an unfixed toner image is not disturbed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electrophotographic recording device, and more particularly, to an electrophotographic recording device that aims to reduce the size and cost of the device, and moreover, to reduce the size and cost of the device. The present invention relates to an electrophotographic recording apparatus that stabilizes the conveying posture of the recording paper and prevents disturbance λ of unfixed toner images when a toner image is melted and fixed by a heat roller.

[Conventional technology]

In an electrophotographic recording device, recording paper stored in a paper cassette passes through a pair of upper and lower paper conveyance rollers to a toner transfer section of a photoconductor, where the toner image on the photoconductor is transferred. is transcribed. After that, the transfer paper is separated from the photoconductor and then conveyed through a paper conveyance section between a pair of upper and lower toner fixing rollers, and the toner image transferred onto the transfer paper is fixed.

However, in conventional electrophotographic recording devices, as described in Japanese Patent Publication No. 62-52300, for example, an endless belt located below an endless belt provided between a toner transfer section and a toner fixing section. , a suction fan is provided that feeds the recording paper to the toner fixing unit in a state in which the recording paper is attracted to the belt, that is, in a state in which the conveyance posture of the recording paper is stabilized;
A sufficient distance is maintained between the toner transfer section and the toner fixing section.

By the way, recently, devices such as optical filing systems that read and print the entire document size have begun to be installed in general office environments, and as their output devices, electrophotographic recording devices such as laser printers are being used. However, in order to make the most effective use of limited space, it is essential that the system as a whole be made compact, and electrophotographic recording devices are also required to be made as compact as possible. It is being

In order to reduce the size of the electrophotographic recording device, the present inventors considered shortening the distance between the toner transfer section and the toner fixing section, and at the same time,
The suction fan of the conventional electrophotographic recording device exemplified in the above publication is located below the endless belt provided between the toner transfer section and the toner fixing section, and the recording paper is attracted to the belt. We focused on the fact that if we could omit the installation of a suction fan that feeds the toner into the fixing section, we could not only make this type of equipment more compact, but also significantly reduce the cost of the fan and fan drive motor.

[Problem to be solved by the invention]

However, simply shortening the distance between the toner transfer section and the toner fixing section will reduce the recording paper transport space within the electrophotographic recording device, and the behavior of the recording paper during transport may cause the printed surface of the recording paper to It has been found that the toner image on the recording paper, which has not yet been fixed, is disturbed due to contact interference with the internal structure of the photographic recording apparatus. This will be explained in more detail based on FIG. 2. In the same figure, a toner image is transferred between the photoreceptor 7 and the toner transfer means 8, and the toner image is transferred between the toner fixing rollers 1 and 2 (heating roller 1 and pressure roller 2). ) The trailing edge of the recording paper 6, which is nipped in the nip section and forcibly conveyed in the paper ejection direction, traces a trajectory as shown by the chain line in FIG. If the distance between the toner fixing unit and the toner fixing unit is simply shortened, the internal structures of the electrophotographic recording apparatus, such as the toner cleaning tool 9, will come into contact with the recording surface near the rear end of the recording paper, and the unfixed recording paper 6 will come into contact with the toner cleaning tool 9. The upper toner image is disturbed. That is, the nip approach angle of the recording paper 6 with respect to the pair of upper and lower toner fixing rollers 1 and 2 changes depending on the paper size on the transfer section side before entering the nip, and as the number of pieces of paper located on the transfer section side decreases, the nip approach angle changes. becomes larger, and the amount of splashing of the piece of paper also becomes larger. Furthermore, since the nip width and nip load in the axial direction of the heating roller 1 are larger at both ends, the conveyance amount of the recording paper 6 is larger at both ends of the heating roller shaft, and the paper gradually reaches the nip. is deformed into a dish-like (concave) shape toward the heating roller 1 side, and the splashing on the heating roller shaft end side becomes large. Note that this dish-shaped deformation of the recording paper 6 also occurs when an inverted crown-shaped heating roller having a diameter larger at the ends than at the center is used.

In addition, in the electrophotographic recording apparatus described in the above-mentioned Japanese Patent Publication No. 62-52300, a guide plate is located on the entrance side of the toner fixing section and applies strain to the recording paper to correct the posture of the recording paper. However, in an electrophotographic recording device in which the distance between the toner transfer section and the toner fixing section is simply shortened, if the guide plate is installed on the toner fixing section side, the toner The influence of applying pressure to the recording paper at the entrance of the fixing unit to spread out the wrinkles on the recording paper extends to the recording paper that is free on the paper conveyance path, changing its posture, and in the worst case, the recording paper The paper may not be inserted smoothly between the pair of upper and lower toner fixing rollers.

In other words, in the middle of the paper conveyance path between the toner transfer section and the toner fixing section, the leading edge of the recording paper is not yet nipped in the nip between the toner fixing rollers, and the trailing edge of the recording paper is not yet held in the nip between the toner fixing rollers. In the electrophotographic recording apparatus described in Japanese Patent Publication No. 62-52300, when the recording paper has already been removed from between the photoreceptor and the toner transfer section, the recording paper is removed by the suction action of the suction fan. The posture of the recording paper is kept constant because it is attracted to the endless belt of In order to reduce the cost of equipment corresponding to the recording paper suction fan and fan drive motor, it is possible to omit the installation of the fan and reduce the conveyance state of the recording paper, that is, the paper between the toner transfer section and the toner fixing section. In the middle of the conveyance path, the front edge of the recording paper has not yet been nipped in the nip between the toner fixing rollers, and the trailing edge of the recording paper has already been pulled out from between the photoreceptor and the toner transfer section. In this state, the straining action on the toner fixing unit side provided with the guide plate, that is, the straining action for smoothing out wrinkles on the recording paper,
The posture of the recording paper in a free state on the paper conveyance path in the traveling direction changes, and in the worst case, the recording paper may not be inserted smoothly between the pair of upper and lower toner fixing rollers.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the size and cost of equipment, and to stabilize the conveyance posture of recording paper when a powder toner image formed on recording paper is melted and fixed by a heated roller. An object of the present invention is to provide an improved electrophotographic recording device that does not cause disturbance of unfixed toner images.

[Means to solve the problem]

The purpose is to provide a means for conveying the recording paper to a toner transfer position, a means for transferring the toner image formed on the photoreceptor onto the recording paper at the transfer position, and a means for fixing the transferred toner image on the recording paper. In an electrophotographic recording device having a recording paper splash prevention paper guide that is positioned so that it does not pass between the body and the toner transfer section, is located on the toner fixing section entrance side of the recording paper, and abuts the back surface of the recording paper in a convex manner; This is achieved by adding .

[Effect]

According to the present invention having the above configuration, the distance between the toner transfer section and the toner fixing section is set such that when the toner fixing section does not yet pinch the leading edge of the recording paper, the distance between the toner transfer section and the toner fixing section is set to Since the positional relationship between the photoreceptor and the toner transfer area has been reduced to such that it does not always pass between the photoreceptor and the toner transfer area, the
More specifically, a conventional electrophotographic recording apparatus as typified by Japanese Patent No. 52300, that is, an electrophotographic recording apparatus in which a sufficient distance is maintained between a toner transfer section and a toner fixing section.

An electrophotographic recording device with a long paper conveyance path in which the trailing edge of the recording paper has already come out from between the photoconductor and the toner transfer section when the leading edge of the recording paper is nipped by the nip of the toner fixing roller. This type of equipment can be made smaller compared to the previous version.

Further, according to the present invention, by providing a paper guide to prevent the paper from splashing up, which is located on the inlet side of the toner fixing section of the paper and comes into contact with the back surface of the paper in a convex manner, it is possible to The convex part pushes up the bottom of the recording paper, and the bending of the paper at that time causes the recording paper to follow the paper guide, and at the same time, it also prevents the plate-shaped deformation of the recording paper mentioned earlier.
Since the unevenness can be reversed from the conventional one, it is possible to eliminate the splashing of the trailing edge of the paper when the recording paper advances to the nip between the toner fixing rollers.

As a result, even if the electrophotographic recording device is downsized and the recording paper conveyance space within the device is reduced, contact between the print surface of the recording paper and internal structures of the electrophotographic recording device, such as toner cleaning tools, will occur. This eliminates interference and does not cause any disturbance to images on recording paper that have not yet been fixed.

In addition, according to the present invention, as described above, the distance between the toner transfer section and the toner fixing section can be adjusted to By positioning the trailing edge of the paper so that it does not always pass between the photoreceptor and the toner transfer area, the recording paper is never free in the middle of the paper transport path, and the Even if the recording paper rides on the recording paper splash prevention guide, the trailing edge of the recording paper is still held between the photoreceptor and the toner transfer section, so the recording paper The movement of the recording paper running onto the guide does not change the orientation of the recording paper in the direction of travel, and this eliminates the problem of the recording paper not being inserted smoothly between the pair of upper and lower toner fixing rollers. By omitting the installation of a recording paper suction fan such as in a conventional electrophotographic recording apparatus as typified by Japanese Patent No. 62-52300, that is, a recording paper suction fan provided in the middle of the paper conveyance path,
The cost of equipment corresponding to the suction fan and fan drive motor can be reduced.

〔Example〕

Hereinafter, the present invention will be described based on the drawings. FIG. 1 is an explanatory diagram of the internal structure of a toner fixing section showing an embodiment of an electrophotographic recording apparatus according to the present invention.

In FIG. 1, 1 is a toner fixing roller (heating roller) coated with a heat-resistant resin with good release properties such as Teflon on the surface of a metal tube with high thermal conductivity such as an aluminum tube, and 2 is the heating roller. Toner fixing roller paired with (
Pressing roller), 3 indicates a heat lamp such as a halogen lamp built into the heating roller 1. The heat lamp 3 heats the toner to a temperature that can melt the toner, and records the toner at the nip between the heating roller 1 and the pressing roller 2. The unfixed toner on the paper is heated and melted to fix the toner. At the same time, the heating roller 1 is rotated in the direction of arrow A by a drive device (not shown), and the recording paper is sequentially conveyed to perform predetermined fixing.

Although not shown (see FIG. 2 if necessary), in the present invention, the distance between the toner transfer section and the toner fixing section is such that the toner fixing section does not touch the leading edge of the recording paper. When not being held, the trailing edge of the recording paper is always in such a position that it does not pass between the photoreceptor and the toner transfer section.

Reference numeral 4 denotes a paper guide for preventing the recording paper from splashing up, which will be described later.This paper guide 4 guides the recording paper carrying an unfixed toner image to the nip between the heating roller 1 and the pressure roller 2. Reference numeral 5 denotes a guide that guides the recording paper to ensure that it enters the nip between the heating roller 1 and the pressure roller 2, so that the recording paper is normally conveyed from the toner transfer section to the toner fixing section. In this case, the recording paper does not come into contact with the guide 5, but if for some reason the recording paper tries to move in the direction of riding on the heating roller 1, the The recording paper is prevented from being raised and guided to the nip between the heating roller 1 and the pressure roller 2.

In the pressure roller 2, the outer periphery of a metal core is covered with a heat-resistant elastic member such as silicone rubber to a certain thickness, and this elastic member is deformed by pressure contact between the heating roller 1 and the elastic member. to form a recording paper nip. FIG. 3 shows an enlarged view of the recording paper nip portion between the heating roller 1 and the pressure roller 2.

In FIG. 3, the recording paper 6 is placed between the heating roller 1 and the pressure roller at the nip approach angle as shown by the broken line in the same figure.
The trailing edge of the recording paper 6 enters the nip between the recording paper 6 and the recording paper 6, and is initially deflected and deformed toward the pressure roller 2 due to the paper's own weight.

However, if the distance between the toner transfer section and the toner fixing section is simply shortened, as described in the [Problems to be Solved by the Invention] section, it is difficult to locate the recording paper in the narrow recording paper conveyance space in the electrophotographic recording device. As a result, due to the behavior of the recording paper during conveyance, the toner image on the recording paper that has not yet been fixed is disturbed due to contact interference between the printed surface of the recording paper and internal structures of the electrophotographic recording apparatus. This will be explained in more detail based on FIG. 2. In the same figure, a toner image is transferred between the photoreceptor 7 and the toner transfer means 8, and the toner image is transferred between the toner fixing rollers 1 and 2 (heating roller 1 and pressure roller 2). )
The trailing edge of the recording paper 6, which is nipped in the nip and forcibly conveyed in the paper ejection direction, traces a trajectory as shown by the chain line in FIG. If the distance between the fixing unit and the fixing unit is simply shortened, the internal structures of the electrophotographic recording apparatus, such as the toner cleaning tool 9, will come into contact with the recording surface near the rear end of the recording paper, and the unfixed recording paper 6
The upper toner image is disturbed. That is, the nip approach angle of the recording paper 6 with respect to the pair of upper and lower toner fixing rollers 1 and 2 changes depending on the weight of the paper on the transfer section side before entering the nip.
As the number of paper pieces located on the transfer section side decreases, the nip approach angle becomes thicker, and the amount of splashing of the paper pieces also increases. Furthermore, since the nip width and nip load in the axial direction of the heating roller 1 are larger at both ends, the conveyance amount of the recording paper 6 is larger at both ends of the heating roller shaft, and the paper gradually reaches the nip portion. is deformed into a dish-like (concave) shape toward the heating roller 1 side, and the splashing on the heating roller shaft end side becomes large.

On the other hand, in the illustrated embodiment, the central convex portion of the paper guide 4 for preventing paper splash-up is set to be closer to the paper nip tangent of the pressure roller 2 (in the direction of the paper nip approach angle) shown by the dashed line in FIG. By disposing it on the heating roller 1 side, the recording paper 6 whose bottom surface is pushed up by the convex part of the guide 4 is bent downward by the pushing up action of the central convex part of the guide 4, and the surface part of the guide 4 is bent downward. 4 and 5 show two specific examples of the guide 4 for preventing splashing of the recording paper 6. FIGS.

Here, the structure and operation of the present invention as typified by the above embodiments will be summarized below.According to the present invention, the distance between the toner transfer section and the toner fixing section can be adjusted by the If the leading edge of the recording paper 6 is not yet pinched,
The trailing edge was made so small that it did not always pass between the photoreceptor and the toner transfer area, so it was
2-52300, that is, an electrophotographic recording device that maintains a sufficient distance between the toner transfer section and the toner fixing section, and more specifically, the front edge of the recording paper. Compared to electrophotographic recording devices with a long paper conveyance path, the trailing edge of the recording paper is already pulled out from between the photoconductor and the toner transfer section when the recording paper is nipped in the nip of the toner fixing roller. It is possible to downsize the equipment.

Further, according to the present invention, the paper guide 4 for preventing the paper from flying up is provided, which is located on the inlet side of the toner fixing section of the recording paper 6 and comes into contact with the back surface of the recording paper 6 in a convex manner. The convex part at the center of the guide pushes up the bottom of the recording paper, and the bending of the paper at that time causes the recording paper 6 to follow the paper guide 4, and at the same time, the plate-shaped deformation of the recording paper mentioned above is also caused. Since the unevenness can be reversed from the conventional one, it is possible to eliminate the splashing of the trailing edge of the paper when the recording paper 6 advances to the nip between the toner fixing rollers 1 and 2, and as a result, the electronic Even if the recording paper conveyance space within the device is reduced by downsizing the photographic recording device, it is possible to eliminate contact interference between the printing surface of the recording paper and internal structures of the electrophotographic recording device, such as toner cleaning tools, and still This does not cause any disturbance to the image on the recording paper 6 that has not been fixed.

In addition to this, according to the present invention, as described above, the distance between the toner transfer section and the toner fixing section is set such that the distance between the toner transfer section and the toner fixing section is set such that when the toner fixing section has not yet pinched the leading edge of the recording paper 6, Since the trailing edge of the recording paper 6 is positioned so that it does not always pass between the photoreceptor and the toner transfer section, the recording paper 6 is never free in the middle of the paper transport path. Therefore, even if the recording paper 6 rides on the recording paper splash prevention guide 4, at this time, the trailing edge of the recording paper 6
Since the recording paper 6 is still held between the photoreceptor and the toner transfer section, the movement of the recording paper 6 onto the guide 4 does not change the attitude of the recording paper 6 in the traveling direction; It is possible to eliminate the problem of the toner not being inserted smoothly between the pair of upper and lower toner fixing rollers 1 and 2, and as a result, the recording paper suction fan of the conventional electrophotographic recording device as typified by Japanese Patent Publication No. 62-52300 can be eliminated. In other words, it is possible to omit the installation of a recording paper suction fan provided in the middle of the paper conveyance path, thereby reducing the cost of equipment corresponding to the suction fan and fan drive motor.

In the above embodiment, one of the pair of upper and lower toner fixing rollers 1 and 2, heating roller 1, is
Although the case where the heater is built-in only in the heating roller 1 and the pressure roller 2 is illustrated, there is no problem in having the heater built-in in both the heating roller 1 and the pressure roller 2.

〔Effect of the invention〕

The present invention is as described above, and according to the present invention, it is possible to reduce the size and cost of equipment, and furthermore, when a powder toner image formed on a recording paper is melted and fixed by a hot roller, the recording paper It is possible to obtain an improved electrophotographic recording apparatus in which the conveyance posture of the toner image is stabilized and unfixed toner images are not disturbed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the internal structure of a toner fixing section showing an embodiment of an electrophotographic recording apparatus according to the present invention, and FIG. 2 is an illustration of the trailing edge trajectory of the recording paper 6 between the toner transfer section and the toner fixing section. 3 is an enlarged view of the recording paper nip portion between the heating roller and the pressure roller 2 shown in FIG. FIG. 4 is a perspective view showing two specific examples of the guide 4. FIG. 1... Toner fixing roller (heating roller), 2... Toner fixing roller (pressing roller), 3... Heat lamp. 4... Recording paper splash prevention paper guide, 6... Recording paper, 7... Photoreceptor, 8... Toner transfer means, 9...
・Toner cleaning tool. Figure 1: Paper guide to prevent recording paper from rising. Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. Means for transporting recording paper to a toner transfer position, means for transferring a toner image formed on a photoreceptor to the recording paper at the transfer position, and a toner image on the transferred recording paper. In an electrophotographic recording device, the distance between the toner transfer section and the toner fixing section is determined by the distance between the toner transfer section and the toner fixing section, when the toner fixing section does not yet hold the leading edge of the recording paper, and the distance between the toner transfer section and the toner fixing section. is a recording paper wing that does not always pass between the photoreceptor and the toner transfer section, is located on the inlet side of the toner fixing section of the recording paper, and is in convex contact with the back surface of the recording paper. An electrophotographic recording device characterized by being equipped with a paper guide to prevent paper from climbing up. 2. In the invention as set forth in claim 1, the central convex portion of the paper guide for preventing the recording paper from rolling up is located closer to the upper fixing roller than the tangent to the recording paper nip of the lower fixing roller among the pair of upper and lower toner fixing rollers. Electrophotographic recording device installed.