JPH0980831A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of outputting both of a smooth toner image with less protuberance and a protuberant toner image by one set. SOLUTION: In the image forming device provided with a latent image forming means for forming an electrostatic latent image on the surface of a photoreceptor drum 39 (image carrier), a developing device (developing means) 31 for developing the electrostatic latent image as a toner image, a transfer electrifier (transfer means) 34 for transferring the toner image on the drum 39 onto a recording material P and a fixing device (fixing means) 100 for heating/fixing the toner image on the recording material P, a toner height level selecting means for selecting the height of the toner image after being heated/fixed and a toner height adjusting means for changing the height of the toner image, in accordance with the selected toner height level are operated by change in the number of image forming times from the same original 19. Thus, the toner image on the recording material P after being heated/fixed can be set at a desired height.

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 photoreceptor or a dielectric 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
The developing means develops a toner image with 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.

By the way, conventionally, as a fixing method in this type of image forming apparatus, a heat roller method has been widely used in which a recording material carrying a toner image is nipped and conveyed by a heating roller and a pressure roller. It was 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 heating 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. 63-313183). ,
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 swelling of the toner from the surface of the recording material is 2.
It is as small as 0 μm. For this reason, it has been difficult to provide information (for example, a copy of a map or a musical score) output by an image forming apparatus adopting such a fixing method to a visually impaired person or the like.

Therefore, an image forming apparatus has been proposed in which development is performed by using a foamed toner that is foamed by heating, and a toner image on a recording material is provided with a protrusion that can be sensed by touch, so that it is convenient for visually impaired persons. There is.

[0007]

However, since an image forming apparatus using a foamed toner can output only a raised image, a user who wants to use a normal image and a raised image separately needs to add to the image forming apparatus using a foamed toner. It is inconvenient because the conventional image forming apparatus must be provided.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of outputting both a smooth toner image having less protrusion and a raised toner image by one unit. To provide.

[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. The toner height step selection means for selecting the height of the toner image and the toner height adjustment means for changing the height of the toner image according to the selected toner height step are used to control the number of times of image formation from the same original. Characterized by doing rather than changing.

According to a second aspect of the invention, in the first aspect of the invention, image formation from the same original is performed plural times on the image carrier, and the formed images are collectively transferred.

According to a third aspect of the invention, in the first aspect of the invention, the images formed from the same original a plurality of times are superposed on the recording material.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, a plurality of developing means are provided, and the developers in the developing means are at least different melting points and different average particle sizes. It is characterized by having been made.

According to a fifth aspect of the invention, in the invention according to the fourth aspect, at least one of the developers has a low melting point and a large particle size, and the other has a high melting point and a small particle size. Characterize.

According to a sixth aspect of the present invention, in the invention according to the fourth aspect, there is provided a plurality of developing means, wherein at least one of them has a low melting point and a large particle size, and the other has a high melting point and a small particle size. It is characterized in that the developing agent is used first, the latter developing agent is used, and the former developing agent is used.

The invention according to claim 7 is the invention according to claims 1, 2, and 3.
Alternatively, in the invention described in 4, the temperature control value of the fixing unit can be switched.

Therefore, according to the first aspect of the present invention, the number of times of image formation from the same original is determined in accordance with the toner height step selected by the operator from a plurality of toner height steps (for example, two steps of smoothness and protrusion). It is possible to set the height of the toner image on the recording material after heating and fixing to a desired height by changing.

According to the invention of claim 2 or 3,
Multiple toner height steps (for example, 2 steps of smooth and raised)
The number of times of image formation from the same original is changed according to the toner height level selected by the operator from the above, and when the number of times of image formation is plural, the images are overlapped on the image carrier or the recording material, so The height of the toner image on the recording material after heat fixing can be set to a desired height.

Further, according to the present invention as defined in claim 4, 5 or 6, there are a plurality of toner height steps (for example, two of smooth and raised).
The height of the toner image on the recording material after heat fixing can be set to a desired height by selecting the developing means in accordance with the toner height step selected by the operator from the step).

Further, according to the invention of claim 7, the temperature control value of the fixing unit is selected according to the toner height level selected by the operator from a plurality of toner height levels (for example, two levels of smoothness and swelling). It is possible to set the height of the toner image on the recording material after heating and fixing to a desired height by switching between.

[0020]

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. In this image forming apparatus, an original 1 is placed on a fixed original glass 20.
When the copy start key (not shown) is pressed after the desired copying conditions are set on the photosensitive drum 39, the photosensitive drum 39, which is an image carrier, moves in the direction of the arrow (clockwise direction) shown in FIG.
It is driven to rotate at 0 mm / sec). In addition, the light source 21 (22
Is a reflection shade) and the first mirror 23 are moved along the lower surface of the platen 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 24 are moved.
When the mirror 25 moves in the same direction at a speed of V / 2, the downward image surface of the document 19 placed on the document glass 20 is illuminated and scanned from the left side to the right side, and the illumination scanning light is reflected on the document surface. The light is imaged and exposed (slit exposure) on the surface of the photosensitive drum 39 via the imaging lens 29 and the fixed fourth 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, An electrostatic latent image having a pattern corresponding to the original image is sequentially formed on the surface of the photosensitive 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 into the transfer portion between the photosensitive drum 39 and the transfer charger 34 at a predetermined timing through the guide 33. Photosensitive drum 3 by receiving the transfer corona
9, the toner images on the surface of the photosensitive drum 39 are sequentially transferred onto the recording material P.

The recording material P which has passed through the image transfer portion is charged by the charge eliminating needle 3.
5 is sequentially separated from the surface of the photosensitive drum 39 while being subjected to the elimination of the rear surface charge, and is conveyed to the fixing device 100 along the conveying portion 38 and the entrance guide 10, and the toner image is fixed in the fixing device 100, and then the image is formed. It is discharged out of the machine as a formed product. In this embodiment, the recording material P
The conveyance speed of is set to 100 mm / sec.
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 the transfer residual toner, and is repeatedly used for image formation.

Thus, when the operator selects the smooth (normal copying) image mode among the toner height steps in the image forming apparatus, an image is formed according to the process described above.

When the operator selects the raised (for example, braille or raised character) image mode, an image is formed on the transfer material P according to the image forming process, and after passing through the fixing device 100, It is sent to the refeed unit. After that, the recording material P is re-fed and sent to the photosensitive drum 39. At that time, an image based on the same original is formed again on the photosensitive drum 39, and the image is transferred by the transfer charger 34 to the same surface of the transfer material P as the first image formation,
Multiple images are formed on the recording material P.

After that, the recording material P again passes through the fixing device 100 to be subjected to image fixing, and since this image is formed twice on the same surface of the recording material P, it becomes a raised image. At this time, a toner having a relatively large particle size (for example,
If the average particle size is 12 to 15 μm), the amount of toner applied increases, so that an image with a higher degree of protrusion can be obtained.

The temperature control temperature of the fixing device 100 can be switched between the smooth image mode and the raised image mode.
In the smooth image mode, the control temperature of the fixing device 100 is set to 190 ° C., for example. At this temperature, the melt viscosity of the toner, which is the developer, is not small, so that the amount of the toner adhering to the roller side when passing through the heating roller 101 is extremely small, the toner itself is not stretched, and the image after fixing rises. The resulting image is smooth. In the raised image mode, the control temperature of the fixing device 100 is set to, for example, 2
Set to 30 ° C. At this temperature, the melt viscosity of the toner is significantly reduced, so that when the toner leaves the pressure contact portion of the fixing device 100, the toner is stretched between the heating roller 101 and the recording material P, and as a result, part of the toner is heated. The toner adhered to the roller 101 and the toner on the recording material P is fixed on the recording material P in a state of being significantly raised. Therefore, it is possible to obtain an image with a higher degree of protrusion.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. Note that FIG. 2 is a configuration diagram of a main part of the image forming apparatus according to the second embodiment of the present invention.

In the image forming apparatus according to this embodiment, when the original 19 is placed on the fixed original glass 20 and the required copying conditions are set and then a copy start key (not shown) is pressed, the photosensitive drum 39 is pressed. Indicates the arrow direction (clockwise)
And is driven to rotate at a predetermined peripheral speed (100 mm / sec). Further, the light source 21 (22 is a reflection shade) and the first mirror 23 are moved along the lower surface of the platen 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,
By moving the second mirror 24 and the third mirror 25 in the same direction at a speed of V / 2, the downward image surface of the document 19 placed on the document table glass 20 is illuminated and scanned from the left side to the right side. The light reflected from the document surface of the illumination scanning light is the imaging lens 2
An image is formed on an image pickup device 70 such as a CCD via 9 and is separated into, for example, two colors of black and red.

By the way, the surface of the photosensitive drum 39 is uniformly charged to a predetermined positive or negative potential by the primary charger 30-1 before image exposure with a laser. The light from the light emitting element 60 is exposed by the scanning device 61 such as a polygon, and electrostatic latent images of patterns corresponding to the original image are sequentially formed on the surface of the photosensitive drum 39. The electrostatic latent image is developed by the developing device 31-. Visualized by 1.

Next, the surface of the photosensitive drum 39 is recharged by the recharger 3.
After being recharged by 0-2, an image exposure corresponding to the second color (for example, red) is performed on the surface of the photosensitive drum 39 by the light emitting element 65 and the scanning device 66 to form an electrostatic latent image. The image is visualized as a second color image by the developing device 31-2. Therefore, two-color images are simultaneously formed on the photosensitive drum 39.

On the other hand, the recording material P is fed by a paper feed roller (not shown).
The recording material P is fed through the guide 33 to the transfer portion between the photosensitive drum 39 and the transfer charger 34 at a predetermined timing and receives the transfer corona, so that the recording material P comes into contact with the photosensitive drum 39. The toner image on the surface of the drum 39 is the recording material P.
Are sequentially transferred to the upper surface of.

The recording material P passing through the image transfer portion is
The charge is removed from the surface of the photosensitive drum 39 while being discharged by the charge removing charger 35, and is introduced into the fixing device 100 along the conveying portion 38 and the entrance guide 10 to receive the toner image fixed in the fixing device 100. After that, the image is discharged outside the apparatus as an image-formed product. Incidentally, in the present embodiment, the conveyance speed of the recording material P is set to 100 mm / sec. 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 the transfer residual toner, and is repeatedly used for image formation.

Thus, when the operator selects the smooth (normal copying) image mode among the toner height steps in the image forming apparatus, an image is formed according to the process described above.

If the operator selects the raised (eg, braille or raised character) image mode, the CCD
Of the two-color image formed on the image 70, only the image signal of the black image (the same image signal) is sent to the two light emitting elements 60 and 65, and as a result, the black image on the photosensitive drum 39 corresponds. Multiple images are formed. At this time, a multiple image of the same image can be obtained with two color toners (black and red, for example)
The image obtained after fixing is almost the same as the black image. In this way, a raised image based on multiple images can be obtained.

A black developing device is arranged on the downstream side, and the toner has a relatively large average particle size (12 to 15 μm).
In addition, if a toner having a low melting point is used, the amount of the toner applied increases, so that an image with a higher degree of protrusion can be obtained.

In the case of a smooth (normal copying) image mode, both of the two developing devices are black developing devices, one light emitting element and one developing device are used for image formation, and a ridge (for example,
In the case of Braille or raised characters image mode, when the method of performing multiple image formation using two light emitting elements (image formation using the same image signal) and two developing devices, smooth mode is used. By using a toner having a high melting point and a relatively small average particle size (7 to 9 μm) in the developing device used in (1), an image without unevenness can be obtained. The reason is that the toner particle size is reduced to prevent the toner image from rising, and the melting point is increased to make it difficult for the toner melt viscosity to be lowered at the time of fixing, so that when the recording material passes through the heating roller, This is because the amount of toner adhered to the roller side (offset amount) becomes extremely small, and the toner itself is not stretched.

On the other hand, a developing device used only in the raised mode has a low melting point and a relatively large average particle size (12 to 15).
(μm) Use a toner so that an image with a large degree of swelling can be obtained. This is because the toner image is raised by increasing the particle size of the toner, and the melting viscosity of the toner at the time of fixing is greatly reduced by lowering the melting point of the toner, so that when the recording material passes through the heating roller, the toner is This is because the amount adhered to the roller side (offset amount) becomes very large and the toner itself is stretched.

In this embodiment, the multiple image is formed on the photosensitive drum, but the same effect can be obtained by forming the multiple image on the transfer drum or the transfer belt.

[0041]

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. The toner height step selecting means for selecting the height and the toner height adjusting means for changing the height of the toner image according to the selected toner height step are performed by changing the number of times of image formation from the same document. Therefore, it is possible to obtain an effect that both a smooth toner image with less protrusion and a raised toner image can be output by one image forming apparatus.

[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 main part of an image forming apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 32 developing device (developing means) 34 transfer charger (transfer means) 39 photosensitive drum (image carrier) 60,65 light emitting element 61,66 scanning device 70 image pickup element 100 fixing device (fixing means) P recording material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Fujita 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Keizo Ogama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Keigo Kaji 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. An image forming apparatus characterized in that the toner height adjusting means for changing the height of the toner image according to the toner height step is performed by changing the number of times of image formation from the same original. 2. The image forming apparatus according to claim 1, wherein image formation is performed a plurality of times from the same original on the image carrier, and the formed images are collectively transferred. 3. The image forming apparatus according to claim 1, wherein images formed a plurality of times from the same original are superposed on a recording material. 4. The image forming method according to claim 1, wherein the image forming apparatus has a plurality of developing means, and the developing agents in the developing means have different melting points and different average particle diameters. apparatus. 5. The image forming apparatus according to claim 4, wherein at least one of the developers has a low melting point and a large particle size, and the other has a high melting point and a small particle size. 6. A developer having a plurality of developing means, at least one of which has a low melting point and a large particle size, and the other of which has a high melting point and a small particle size, and the latter developer is used to develop first. 5. The image forming apparatus according to claim 4, wherein the former developer is used for later development. 7. The image forming apparatus according to claim 1, wherein the temperature control value of the fixing unit is switchable.