JPH0980955A - Image forming device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide an image forming apparatus capable of outputting both a smooth toner image with less protrusion and a raised toner image. A latent image forming means for forming an electrostatic latent image on the surface of a photosensitive drum 39 (image carrier), a developing device (developing means) 31 for developing the electrostatic latent image as a toner image, and the photosensitive drum 39. A transfer charging device (transfer means) 34 that transfers the upper toner image onto the recording material P, and a fixing device (fixing means) that heat-fixes the toner image transferred onto the recording material P onto the recording material P.
In an image forming apparatus equipped with 100, a toner height step selecting means for selecting the height of a toner image after heat fixing, and a toner image height after heat fixing depending on the selected toner height step selecting means. A toner height adjusting means (driving device 40) for changing

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 copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a laser beam printer which employs an electrophotographic system or an electrostatic recording system, when an image is formed, first of all, a photosensitive member or a dielectric member as an image carrier is used. An original image or an electrostatic latent image corresponding to an input image signal is formed on the surface. This electrostatic latent image is developed as a toner image by the developing means using toner having a predetermined charge. Then, the toner image developed on the image carrier is electrostatically transferred onto the recording material by the transfer means, and the toner image on the recording material is fixed onto the recording material by the fixing means.

Conventionally, as a fixing system in this type of image forming apparatus, a heat roller system in which a recording material carrying a toner image is nipped and conveyed by a heating roller and a pressure roller has been widely used. In such a heat roller system, since the heat capacity of the heating roller is large, there is a problem in that it takes a long time to heat the heat roller to a predetermined temperature (so-called warm-up time).

Therefore, there has been proposed a film heat fixing system in which a warm-up time is shortened by using a thermal head having a low heat capacity and a thin film sliding on the thermal head (Japanese Patent Laid-Open No. 63-313182). ,
See JP-A-2-1577878.

However, when the above-mentioned fixing system is used, the toner on the recording material receives heat and pressure at the fixing nip portion, so that the amount of protrusion of the toner from the surface of the recording material is 1.
It is as small as 0 μm. Therefore, it is difficult to provide the information (for example, a copy of a map or a musical score) output by this type of image forming apparatus to the visually impaired person or the like.

Therefore, an image forming apparatus has been proposed in which a toner image formed on a recording material is provided with a protrusion that can be recognized by touch using a foamed toner that is foamed by heating, which is convenient for visually impaired persons.

[0007]

However, since the conventional image forming apparatus using the foamed toner can output only the raised image, the user who wants to use the normal image and the raised image properly can select the image forming apparatus using the foamed toner. In addition, it is necessary to have a conventional image forming apparatus, which is inconvenient.

The present invention has been made in view of the above problems, and an object of the present invention is to output both a smooth toner image with less protrusion and a raised toner image by one unit, and to increase the toner amount. An object of the present invention is to provide an image forming apparatus capable of preventing offset toner from being redeposited on a recording material depending on the level.

[0009]

In order to achieve the above object, the invention according to claim 1 is a latent image forming means for forming an electrostatic latent image on the surface of an image carrier, and the electrostatic latent image is a toner image. In the image forming apparatus, a developing unit for developing the toner image, a transfer unit for transferring the toner image on the image carrier onto a recording material, and a fixing unit for fixing the toner image on the recording material by heating are fixed. Toner height step selecting means for selecting the height of the toner image, toner height adjusting means for changing the height of the toner image after heat fixing according to the selected toner height step, and the fixing means. Offset toner re-adhesion preventing means for preventing the offset toner that has adhered away from the recording material from adhering to the rear portion in the transport direction of the recording material or another recording material again is provided.

A second aspect of the invention is characterized in that, in the first aspect of the invention, the offset toner readhesion preventing means has an offset toner cleaning means.

According to a third aspect of the present invention, in the second aspect of the invention, the offset toner cleaning means is changed according to a selected toner height step.

According to a fourth aspect of the present invention, in the invention according to the second or third aspect, the fixing means is composed of a roller-like heating means which is rotatably supported, and a pressurizing means which is brought into pressure contact with the heating means. In the formed pressure contact portion, the recording material carrying the unfixed toner image is sandwiched and conveyed, and the circumferential length of the heating means is set to be larger than the length in the conveying direction of the recording material. And

According to a fifth aspect of the invention, in the inventions of the second, third or fourth aspect, when continuous image formation is performed,
The distance between the recording materials is changed according to the selected toner height level.

According to a sixth aspect of the present invention, in the first or fourth aspect of the invention, after the recording material passes through the pressure contact portion, the member having a length in the transport direction larger than the circumferential length of the heating means is provided. It is characterized in that the pressure contact portion is passed.

According to a seventh aspect of the present invention, in the second or third aspect of the invention, the fixing means is in contact with the recording material and a heat-resistant sheet that moves at the same speed as the conveying speed of the recording material is interposed. At a pressing portion formed by a fixed linear heating element and a pressing means that is pressed against the heating element, the recording material carrying the unfixed toner image is nipped and conveyed between the heat resistant sheet and the pressing means. With this configuration, the length of the heat resistant sheet in the moving direction is set to be larger than the length of the recording material in the conveying direction.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> FIG. 1 is a block diagram of an essential part of an image forming apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a block diagram of a fixing device of the image forming apparatus.

The image forming apparatus according to the present embodiment is a manuscript table fixing / optical system moving type / rotating drum type / transfer type electrophotographic copying machine. In the copying machine, a manuscript is fixed on a fixed manuscript table glass 20. When the copy start key (not shown) is pressed after placing 19 and setting the required copying conditions, the photosensitive drum 39, which is an image carrier, moves in the direction of the arrow (clockwise) in the figure at a predetermined peripheral speed (100 m / s). ) Is driven to rotate. or,
The light source 21 (22 is a reflection shade) and the first mirror 23 move along the lower surface of the document table glass 20 from the home position on the left side of the glass to the right side of the glass at a predetermined speed V, and the second mirror 24 and the third mirror. 25 moves in the same direction at a speed of V / 2, so that the document 1 placed on the platen glass 20
The downward image plane of 9 is illuminated and scanned from the left side to the right side,
The illumination scanning light reflected by the document surface is imagewise exposed (slit exposure) on the surface of the photosensitive drum 39 via the imaging lens 29 and the fixed first to sixth mirrors 26, 27 and 28.

By the way, the surface of the photosensitive drum 39 is uniformly charged to a predetermined positive or negative potential by the primary charger 30 before exposure, and when this charged surface is exposed to light, it is exposed. An electrostatic latent image having a pattern corresponding to the original image is sequentially formed on the surface of the drum 39. Then, the electrostatic latent image formed on the surface of the photosensitive drum 39 is developed by the toner carried on the developing roller 32 of the developing device 31 and visualized as a toner image.

On the other hand, the recording material P is fed by the paper feed roller 51, and the recording material P is introduced through the guide 33 to the transfer portion between the photosensitive drum 39 and the transfer charger 34 at a predetermined timing and transferred. By receiving the corona, the toner image comes into contact with the photosensitive drum 39, and the toner images on the surface of the photosensitive drum 39 are sequentially transferred to the upper surface of the recording material P. Then, the recording material P that has passed through the image transfer section is sequentially separated from the surface of the photosensitive drum 39 while being discharged by the charge removal needle 35, and is introduced into the fixing device 100 through the transport section 38 and the entrance guide 10. After the toner image is fixed by the fixing device 100, the toner image is discharged outside the apparatus as an image-formed product. Incidentally, in the present embodiment, the conveying speed of the recording material P is set to 100 mm / s. Further, the surface of the photosensitive drum 39 after the transfer is cleaned and removed by the cleaning blade 37 of the cleaning device 36, such as transfer residual toner, and is repeatedly used for image formation.

The fixing device 100 will be described with reference to FIG.

In FIG. 2, 111 is a heating roller as a heating means, which is formed by coating a fluorocarbon resin having a thickness of 20 μm around a carbon steel core bar having a surface length of 310 mm and a wall thickness of 0.2 mm to 0.3 mm. A heater 110 such as a halogen heater having a rating of 500 to 1000 W is provided inside the fixing roller 111. The heating roller 111 is rotationally driven at a predetermined timing by a driving device (not shown). The heating roller 111 is attached to the pressure roller 11
No. 2 is rotatably pressed under a total weight of 5 kg to 30 kg. The pressure roller 112 has a core metal made of carbon steel coated with silicone rubber, and its outer periphery coated with a tube made of fluororesin. Is configured.

In the fixing device 100, the heating roller 1 is held while the recording material P carrying the toner image on the surface is nipped and conveyed by the heating roller 111 and the pressure roller 112.
The heat of the surface of 11 melts the toner and fixes it on the recording material P.

By the way, in the vicinity of the heating roller 111,
Fixing cleaner (fixing cleaner A) in "smooth image mode"
113 and a fixing cleaner (fixing cleaner B) 11 in the "raised image mode" with high offset toner cleaning ability
4 are installed. The fixing cleaner A113 is a roller-shaped fixing cleaner that comes into contact with the heating roller 111 and is driven to rotate. Further, the fixing cleaner B114 is a fixing cleaner having a web made of aramid fiber impregnated with silicone oil having a high ability to clean the toner adhering to the heating roller 111.

When the "smooth image mode" in which almost no toner remains on the heating roller 111 is selected, the heating roller 11
The fixing cleaner A113 is in contact with 1. At this time, the fixing cleaner B114 is separated from the heating roller 111. This is because the fixing cleaner B114 is constantly brought into contact with the heating roller 111,
This is to prevent the material from being worn. When the "raised image mode" is selected, the fixing cleaner A113 is the heating roller 11
1, the fixing cleaner B114 is separated from the heating roller 11
Abut 1.

The heating roller 111 to the pressure roller 11
In order to remove the toner transferred to the pressure roller 11, the pressure roller 11
Alternatively, a cleaning device may be separately provided in No. 2. In this case, the cleaning device may always be in contact with the pressure roller 112.

Further, instead of using the two fixing cleaners of the fixing cleaner A113 and the fixing cleaner B114, it is possible to obtain the same effect by using one fixing cleaner. For example, in the “smooth image mode”, the web is brought into contact with the heating roller 111 in a small area with a light pressure.
Compared to the “smooth image mode”, the “elevated image mode” is designed to contact with a large area at high pressure.

By configuring the fixing device 100 as described above, it becomes possible to completely remove the offset toner corresponding to the selected toner height step, and the offset toner is prevented from adhering to the recording material P again. Can be prevented.

<Second Embodiment> Next, a second embodiment of the present invention will be described.

In the present embodiment, when the operator selects the "raised image mode", after the image is formed, the heating roller and the pressure roller are rotated for a predetermined time until the next image is formed. I am trying. Thus, the toner remaining on the heating roller and the pressure roller can be removed by the fixing cleaner. In that case, it is effective to set the surface temperature of the heating roller to a predetermined temperature lower than that at the time of image formation, to enhance the bonding force between the resins forming the toner, and to easily remove the toner from the surface of the heating roller. Target.

With the above structure, it is possible to prevent the offset toner from reattaching to the recording material.

<Third Embodiment> Next, a third embodiment of the present invention will be described.

Also in the present embodiment, as in the case of the second embodiment, when the "raised image mode" is selected by the operator, a predetermined time is elapsed between the image formation and the next image formation. Only the heating roller and the pressure roller are rotated while the offset toner is removed by the fixing cleaner.

In this embodiment, the circumferential length of the heating roller is set larger than the length of the recording material in the conveying direction. Therefore, it is possible to prevent the toner adhering to the heating roller from re-adhering to the rear portion of the same recording material when being conveyed to the pressure contact portion of the heating roller and the pressure roller as the heating roller rotates. Then, as described above, by rotating the heating roller and the pressure roller until the next recording material is conveyed to the fixing unit, the offset toner is removed by the fixing cleaner, and the offset toner is regenerated on the next recording material. It is possible to prevent the adhesion.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram of the fixing device of the image forming apparatus according to the fourth embodiment of the present invention.

In the present embodiment, when the operator selects the "raised image mode", the recording material P is overlaid on the fixing cleaning member 115 to perform copying.

The fixing cleaning member 115 is coated on its surface with a material to which toner easily adheres (for example, polyester resin when the main raw material of the toner is polyester resin). The circumference of the heating roller 111 is larger than the length of the recording material P in the conveying direction, and the length from the rear end of the recording material P to the rear end of the fixing cleaning member 115 is set larger than the circumference of the heating roller 111. ing.

With the above configuration, when the operator selects the "raised image mode" to perform copying, the toner adhering to the heating roller 111 is applied to the heating roller 111 and the pressure roller 112 at the pressure contact portion. When the toner returns with the rotation of 111, the toner is collected by the fixing cleaning member 115 without reattaching to the recording material P.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIG. Incidentally, FIG. 4 is a fixing device (surf fixing device) of the image forming apparatus according to the fifth embodiment of the invention.
FIG.

In this embodiment, when the operator selects the "raised image mode", the cleaning roller 18 is pressed against the fixing film 6, and the cleaning roller 18 removes the offset toner from the fixing film 6.

When the operator selects the "smooth image mode", the cleaning roller 18 is separated from the fixing film 6 and wear caused by the contact of the fixing film 6 with the cleaning roller 18 is prevented.

In the fixing device shown in FIG. 4, 1 is a low heat capacity linear heater, 2 is a substrate, 3 is a heating layer, 4 is a protective layer such as glass, 5 is a thermistor such as NTC thermistor, 7
Is a drive roller, 8 is a driven roller, 9 is a pressure roller, 10
Is an inlet guide, 11 is a heater support, 12 is a paper ejection guide, 16 is an energization control device, 19 is a solenoid, 20 is a link, 21 is a drive device, 22 is a cleaning roller cleaning member, 23 is a scraper, and 117 is high toner. A switch is a selection unit, N is a fixing nip portion, and P is a recording material.

[0043]

As is apparent from the above description, according to the present invention, latent image forming means for forming an electrostatic latent image on the surface of an image carrier and developing for developing the electrostatic latent image as a toner image. In the image forming apparatus, the image forming apparatus includes a unit, a transfer unit that transfers the toner image on the image carrier onto a recording material, and a fixing unit that heat-fixes the toner image on the recording material. Toner height level selecting means for selecting the height, toner height adjusting means for changing the height of the toner image after heat fixing in accordance with the selected toner height level, and the recording material to the fixing means. Since offset toner re-adhesion preventing means for preventing the offset toner that has adhered away from adhering again to the rear portion of the recording material in the conveying direction or another recording material is provided, a toner image that is smooth and has little protrusion can be obtained with one unit. Raised toner It is possible to output both image, there is an advantage that it is possible to prevent re-adhesion of the recording material of the offset toner according to toner height steps.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a fixing device of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a fixing device of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 4 is a configuration diagram of a fixing device (surf fixing device) of an image forming apparatus according to a fifth embodiment of the present invention.

[Explanation of symbols]

6 Fixing Film 18 Cleaning Roller 111 Heating Roller 112 Pressure Roller 113 Fixing Cleaner (Fixing Cleaner A) in “Smooth Image Mode” 114 Fixing Cleaner (Fixing Cleaner B) in “Protruding Image Mode” 115 Fixing Cleaning Member P Recording Material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hidekazu Maruta 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hideki Fujita 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Incorporated (72) Inventor Keizo Oara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (7)

[Claims] 1. A latent image forming means for forming an electrostatic latent image on the surface of an image carrier, a developing means for developing the electrostatic latent image as a toner image, and a toner image on the image carrier on a recording material. In the image forming apparatus including the transfer unit for transferring the toner image onto the recording material and the fixing unit for fixing the toner image on the recording material by heat, the toner height step selecting unit for selecting the height of the toner image after the heat fixing is selected. The toner height adjusting means for changing the height of the toner image after heating and fixing according to the toner height step, and the offset toner adhering to the fixing means apart from the recording material are then again conveyed in the conveying direction of the recording material. An image forming apparatus comprising offset toner readhesion preventing means for preventing the toner from adhering to a rear portion or another recording material. 2. The image forming apparatus according to claim 1, wherein the offset toner readhesion preventing unit includes an offset toner cleaning unit. 3. The image forming apparatus according to claim 2, wherein the offset toner cleaning unit changes according to a selected toner height level. 4. The recording unit carrying an unfixed toner image at a pressure contact portion formed by a roller-shaped heating unit rotatably supported and a pressure unit opposed to the heating unit. The material is sandwiched and conveyed, and the circumferential length of the heating means is set to be larger than the length of the recording material in the conveying direction.
The image forming apparatus as described in the above. 5. The image forming apparatus according to claim 2, 3 or 4, wherein, when images are continuously formed, an interval between the recording materials is changed according to a selected toner height step. . 6. The member according to claim 1, wherein after the recording material has passed through the pressure contact portion, a member having a conveyance direction length larger than the circumferential length of the heating means is passed through the pressure contact portion. Image forming device. 7. The fixing means is in contact with the recording material and is pressed against the fixed linear heating element and the heating element via a heat-resistant sheet which moves at the same speed as the conveying speed of the recording material. A recording material carrying an unfixed toner image is sandwiched and conveyed between the heat resistant sheet and the pressure applying means at a pressure contact portion formed by a pressure means, and the length of the heat resistant sheet in the moving direction is the recording material. The image forming apparatus according to claim 2, wherein the length is set to be larger than the length of the sheet in the conveyance direction.