JPH10232582A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform a fixing process and to output a sharp image by fixing an image under the same conditions as those used for plain paper in the case a transfer material is a monochrome OHP sheet. SOLUTION: In a color OHP sheet, a PET film is coated with resin. For example, in a color data mode, when magenta toner and yellow toner are transferred and fixed to it, light from a projector is transmitted through the resin on the film and the melted and fixed toner, and projected as red on a screen. In this case, it is necessary to mix the magenta toner and yellow toner sufficiently, and a sufficient amount of heat is required to fix them. In the case of a monochrome image, on the other hand, it is not necessary for black toner to transmit light, and an amount of heat required to fix the image is smaller than that required to fix the color image. Therefore, when the color OHP sheet is detected by a transfer front end sensor and the data of an original document is monochrome, fixing is carried out under the same conditions as in the case of image formation on plain paper used as a transfer material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type color image forming apparatus such as a color copying machine or a color printer, and more particularly to a fixing device.

[0002]

2. Description of the Related Art A color image forming apparatus that uses a toner as a developer and obtains a color image on a transfer material by superimposing toner images of a plurality of colors on a transfer material is charged, exposed, and developed to form a toner image. There is a method in which a color image is obtained by superimposing a plurality of color toner images on a transfer material by repeating the process of forming an image and transferring the toner image onto a transfer material every time a toner image is obtained. This type of color image forming apparatus has been put to practical use with a configuration described in German Patent Application DE 2607727, Japanese Patent Application Laid-Open No. 50-50935, and the like.

FIG. 9 is a block diagram showing the above-mentioned color image forming apparatus. As shown, a photosensitive drum 1 as an image carrier is provided in the apparatus, and a roller charger is provided around the photosensitive drum 1. A primary charging device 3 serving as a charging unit, a rotary developing device 4 having a plurality of developing devices, a transfer device 10A, and a cleaner 26 are provided. Above the photosensitive drum 1, a laser diode 11 constituting exposure means, a polygon mirror 13 rotated by a high-speed motor 12, a lens 1
4 and a folding mirror 15 are arranged.

The photosensitive drum 1 is formed by coating a photoconductor made of an organic photoconductor (OPC) on an outer peripheral surface of an aluminum cylinder having a diameter of 40 mm. The photoconductor may be amorphous Si, CdS, Se, or the like. The photosensitive drum 1 is rotated in a direction indicated by an arrow at a peripheral speed of 100 mm / sec by a driving unit (not shown).

[0005] The developing device 4 has a support 9 which rotates around a central rotation axis 9a. The support 9 is provided with a yellow developing device 4a, a magenta developing device 4b, a cyan developing device 4c and a black developing device 4d. It is doing. Each developing unit 4a
4d contain yellow toner, magenta toner, cyan toner, and black toner, respectively.

As shown in FIG. 10, in each of the developing devices 4a to 4d, a developing sleeve 8a, 8b, 8 is formed as a developer carrier at a position facing the opening surfaces 5a, 5b, 5c, 5d.
c and 8d are installed. Further, in each of the developing devices 4a to 4d, application rollers 6a, 6b, 6c, 6d and toner regulating members 7a, 7b, 7c, 7d are installed.

[0007] With the rotation of the developing sleeves 8a to 8d, toner is applied onto the developing sleeves 8a to 8d by the application rollers 6a to 6d, and the toner is regulated so that a triboelectric charge is given to the toner. A thin toner layer is formed on 8a to 8d. This toner regulating member 7
a to 7d are preferably materials that are charged in the opposite direction to the charging polarity of the toner, such as nylon when the toner is charged to a negative polarity, and silicone rubber or the like when the toner is charged to a positive polarity.

The developing sleeves 8a to 8d of the developing units 4a to 4d
The peripheral speed of 8d is 1.0 to 1.0 in the peripheral speed ratio with respect to the photosensitive drum 1.
It is preferable to select so as to be in the range of 2.0 times.
When the developing units 4a to 4d face the photosensitive drum 1, the developing units 4a to 4d are driven such that their opening surfaces 5a to 5d always face the photosensitive drum 1. Details of the driving means of these developing units 4a to 4d are as described in JP-A-50-93437.

The transfer device 10A includes a transfer drum 10 as a transfer material carrier. Around the transfer drum 10, an attraction roller 23, a static eliminator 2, a separation claw 24, a cleaner 27, and a static elimination roller 28 are disposed. I have. Transfer drum 10
A gripper 2 of a transfer material gripping member
Two. The transfer drum 10 is rotated in a direction indicated by an arrow at substantially the same speed as the photosensitive drum 1 by a driving unit (not shown).

In the image forming apparatus having the above configuration, first, the primary charger 3 is supplied with a DC voltage of -700 V and a frequency of 700H.
z, Vpp (peak-to-peak voltage) -1500V
Is applied, and the surface of the photosensitive drum 1 is primarily charged to about -700V. Next, a signal according to the first color, for example, a yellow image pattern is input to the laser diode 11 to generate light of a yellow image pattern, and the light is irradiated to the photosensitive drum 1 through the optical path 16 to expose the photosensitive drum 1 to light. On the drum 1, an electrostatic latent image having a yellow image pattern with a light irradiation part of approximately −100 V is formed.

An electrostatic latent image of a yellow image pattern formed on the photosensitive drum 1 is developed by a yellow developing unit 4a located there at a developing unit facing the developing device 4 as the photosensitive drum 1 rotates. As a result, a first color yellow toner image is formed on the photosensitive drum 1.

On the other hand, transfer paper is supplied from a transfer material cassette 17 to the transfer drum 10 of the transfer device 10A by a pickup roller 18 in synchronization with an image on the photosensitive drum 1. The transfer drum 10 transfers the supplied transfer paper to the gripper 2.
2 and rotate in the direction of the arrow in the figure, thereby transporting the photosensitive drum 1 to the image transfer unit facing the photosensitive drum 1. The transfer paper applied to the image transfer unit transfers a yellow toner image on the photosensitive drum 1 by a transfer voltage applied between the transfer drum 10 and the photosensitive drum 1 by a power supply (not shown).

At the same time as the transfer, electric charges are injected into the transfer paper by the transfer voltage, and the transfer paper is electrostatically attracted to the surface of the transfer drum 10 and held. In order to enhance the electrostatic attraction of the transfer paper to the transfer drum 10, the gripper 23 is installed near the paper feeding portion of the transfer drum 10 and a voltage for suction is applied to the transfer roller 10. In many cases, the transfer paper is electrostatically adsorbed in advance after the holding by the grip 22.

The photosensitive drum 1 on which the transfer of the yellow toner image has been completed is cleaned and removed of residual toner on the surface thereof by a cleaning member such as a fur brush or a blade provided on a cleaner 26, and is then charged by a primary charger 3 or less. Is performed.

The primary charging of the photosensitive drum 1 as described above, the formation of an electrostatic latent image by exposure, the formation of a toner image by developing the electrostatic latent image, and the superimposed transfer of the obtained toner image onto transfer paper are performed. By performing the same for magenta, cyan, and black of the second and subsequent colors, toner images of four colors of yellow, magenta, cyan, and black are superimposed on the transfer paper and transferred, and a color image is obtained.

The transfer paper on which the transfer of the toner images of the four colors is completed is then discharged by the discharging charger 2 disposed around the transfer drum 10 and then separated from the transfer drum 10 by the separation claw 24 on the downstream side. To the fixing device 25. Then, the toner images of four colors are fixed by heating and pressurizing, and the color mixture of the toner images and fixing to the transfer paper are performed to form a full-color permanent image, which is then discharged outside the image forming apparatus. Preferably, residual toner on the surface of the transfer drum 10 from which the transfer paper has been removed is cleaned by a cleaner 27 having a cleaning member such as a fur brush or a web.

Next, the fixing device 25 will be described in detail with reference to FIG. The fixing device 25 includes a fixing roller 29 in which a heater 31 is provided in a core 30 made of aluminum, and a silicone rubber layer 32 is formed on the core 30.
A heater 35 is provided in a metal core 34 also made of aluminum, and pressure rollers 33 having a silicone rubber layer 36 formed on the metal core 34 are pressed against each other, and are rotatably arranged in the arrow direction shown in the figure. Is established. The rollers 29, 3
The fixing temperature of 3 is controlled by a thermistor 54 in contact with the pressing roller 33, the fixing roller 29 is rotated via a drive source not shown, and the pressing roller 33 is driven to rotate by the fixing roller 29. . The fixing speed is appropriately changed by controlling the rotation speed of the driving source.

The load between the rollers is about 10 to 60 kg, the nip width is 2 to 8 mm, and the silicone rubber layers 32, 3
6 have a thickness of 2 to 3 mm, respectively.

A fixing entrance guide 37 is provided in front of the two rollers, and a fixing exit guide 38 is provided in the rear. The transfer paper guided by the fixing entrance guide 37 is used to transfer the transfer paper guided by the rollers 29 and 33. The sheet is heated and pressed while being pinched and conveyed, and is discharged along the fixing exit guide 38.

Therefore, the unfixed toner image transferred on the transfer paper through the above-described development and transfer steps comes into contact with the surface of the fixing roller 29, so that the toner not fixed on the surface of the fixing roller 29 is removed. In some cases, the toner adhered to the pressure roller 33.

In order to prevent the toner from adhering to the silicone rubber layer, that is, the so-called offset phenomenon,
Silicone oil is supplied to both rollers.

The fixing conditions for plain paper are as follows: fixing temperature = 167 ° C. ± 10 ° C. fixing speed = 100 mm / sec. It is. The fixing conditions for the OHP sheet are as follows: fixing temperature = 167 ° C. ± 10 ° C. fixing speed = 50 mm / sec. It is.

Since the OHP sheet is made of a resin film such as PET, the OHP sheet has a larger heat capacity than paper, and
When fixing the above toner, a larger amount of heat is required. In this conventional example, in the case of an OHP sheet, the fixing was performed under the above-mentioned conditions in which the fixing speed was reduced.

In the case of a color image, a clear image having transparency cannot be obtained unless the toner is sufficiently melted, so that a larger amount of heat is required as compared with paper.

[0025]

As described above, when fixing an OHP sheet, the transport speed must be reduced. Also, there has been a problem in terms of speed and power consumption, such as the need to increase the temperature during fixing. Of the color image forming apparatuses, the use as a printer is often used in a black-and-white mode.
In some cases, both P sheets and OHP sheets for color were used, resulting in a reduction in speed and an increase in the amount of heat.

Accordingly, it is an object of the present invention to provide a fixing device which can efficiently execute a fixing process when a black-and-white OHP sheet is fed or when black-and-white image data is supplied to the main body of the apparatus. It is to provide a color image forming apparatus which can be used.

[0027]

The above object is achieved by a color image forming apparatus according to the present invention. In summary, the present invention provides a fixing device for fixing a developed image by heating or pressing a transfer material on which a developed image is formed, a control unit for controlling a transfer material conveying speed or a heating temperature of the fixing device, and a transfer device. In a color image forming apparatus having an OHP sheet detecting means for detecting whether the material is a color OHP sheet or a black-and-white OHP sheet, if the transfer material is a black-and-white OHP sheet, the fixing is performed under the same fixing conditions as plain paper. This is a color image forming apparatus.

According to another aspect of the present invention, a fixing device for fixing a developed image by heating or pressing a transfer material on which a developed image is formed, and controlling a transfer material transport speed or a heating temperature of the fixing device. A color image forming apparatus including a control unit and an OHP sheet detection unit configured to detect whether the transfer material is a color OHP sheet or a black-and-white OHP sheet;
When an image is formed using only black and white image data, a color image forming apparatus is provided which is fixed under the same fixing conditions as plain paper regardless of the type of transfer material.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a color image forming apparatus according to the present invention will be described in more detail with reference to the drawings. In the embodiment described below, it is assumed that the present invention is embodied in the color image forming apparatus shown in FIG. Therefore, a detailed description of the overall configuration and functions of the color image forming apparatus will be omitted, and features of the present invention will be described.

Embodiment 1 Embodiment 1 according to the present invention will be described with reference to FIGS.

First, the paper feeding system of the color image forming apparatus according to the present embodiment will be described with reference to FIG. In the figure,
An OHP sheet (overhead project recording material) 101 stacked on the multi-tray 107 is conveyed into the main body by a pickup roller 102,
When the front end of the OHP sheet comes out of the registration roller 104 through the registration roller 104 by about 15 mm after passing through No. 3, it is temporarily stopped. At this time, the transfer material leading edge sensor 105 detects the leading edge of the OHP sheet 101.

OHP sheets are roughly classified into color OHP sheets.
As shown in FIG. 2, the color OHP sheet 101 a has a leading end portion in the moving direction, that is, a portion corresponding to the transfer material leading end sensor 105 when stopped by the registration roller 102. Is coated with a paint 201 that reduces the light transmittance (50% or less). On the other hand, as shown in FIG.
The paint 201 is not printed on the P sheet 101b.

Here, the difference between a case where a color image and a monochrome image are formed on the color OHP sheet 101a and which are projected on a screen by a projector will be described with reference to FIGS. 4 and 5. FIG.

As shown in FIG. 4, the OHP sheet for color 101a has a PET film 302 coated with a resin 301 (resin layer thickness = 3 to 10 μm). For example, a magenta toner 306 and a yellow toner are used in a color data mode. When the image 305 is transferred and fixed, the light from the projector passes through the resin 301 on the film and the toner fused and fixed, and the red (red) 3
04 is projected. Magenta toner 3
06 and the yellow toner 305 must be sufficiently mixed, and a sufficient amount of heat is required for fixing.

On the other hand, in the case of a black-and-white image, as shown in FIG. 5, the black toner 308 does not need to transmit light (reflects or absorbs to the toner), so that the black toner 308 needs to be sufficiently melted. Therefore, the amount of heat at the time of fixing is less required than in the case of a color image.

Therefore, conventionally, the transfer material leading edge sensor 105
When the color OHP sheet 101a is detected and the original is black and white data, the fixing is performed under the fixing condition specific to the color regardless of the color data or the black and white data. The fixing was performed under the same conditions as those for forming an image on plain paper. The fixing conditions at this time are as shown in Table 1 (1).

[0037]

[Table 1]

The transfer material is a color OHP sheet,
If the printed image is black and white data, even if projected on the screen with a projector,
A contrast ratio can be obtained regardless of transmittance, and a clear image can be obtained.

As described above, in this embodiment, when a color OHP sheet is detected as a recording material, and in the case of black and white image data, fixing is performed under the same fixing conditions as plain paper, so that the fixing speed and the fixing An image could be efficiently output in terms of temperature, and a sufficiently clear image could be obtained.

Embodiment 2 Next, Embodiment 2 of the present invention will be described. In this embodiment, the black and white O
When the HP sheet is fed, fixing is performed under the same fixing conditions as plain paper as a transfer material.

In FIG. 1, when the monochrome OHP sheet 101b is mounted on the multi-tray 107, a transfer material presence / absence sensor (not shown) provided on the tray first determines that the sheet is plain paper or an OHP sheet and prints. When the signal enters the apparatus main body, the pickup roller 102 operates, and the black and white OHP sheet 101b is transported by the transport roller 103 to the registration roller 104.

When the leading edge of the monochrome OHP sheet 101b reaches the leading edge sensor 105 of the transfer material, light is transmitted by the leading edge sensor 105 as in the first embodiment, so that the black / white OHP sheet 101b is transmitted.
It is determined to be an HP sheet.

As described above, the type of the OHP sheet used in this embodiment is the OHP sheet 101 for color shown in FIG.
The mark 201 printed on the black and white OH in FIG.
This is determined based on the absence of the mark 201 on the P sheet 101b. Further, as shown in FIG. 6, the OHP sheet 101b for black and white only has the antistatic material 402 applied to both sides of the PET resin 401.

In this embodiment, when the image data is black and white and the OHP sheet 101b for black and white is selected as the transfer material, printing is automatically performed under the same conditions as plain paper.

The fixing conditions of this embodiment are the same as those of the paper of the first embodiment. That is, fixing temperature = 157 to 177 ° C. conveyance and fixing speed = 10
0 mm / sec. It is.

In this embodiment, when a black-and-white OHP sheet is used under these fixing conditions, a clear image can be printed efficiently without reducing the fixing speed or increasing the amount of heat even if the OHP sheet is used. can do.

Third Embodiment Next, a third embodiment of the present invention will be described. In this embodiment, when a black-and-white OHP sheet is fed and color image data is sent to the image forming unit, fixing is performed under the same fixing conditions as for plain paper.

In FIG. 1, when the black-and-white OHP sheet 101b is mounted on the multi-tray 107, a transfer material presence / absence sensor (not shown) provided on the tray first determines that the sheet is plain paper or an OHP sheet. When the signal enters the apparatus main body, the pickup roller 102 operates, and the black and white OHP sheet 101b is transported by the transport roller 103 to the registration roller 104.

When the leading edge of the OHP sheet 101b for black and white reaches the transfer material leading edge sensor 105, light is transmitted by the same leading edge sensor 105 as in the first embodiment, so that the monochrome
It is determined to be an HP sheet.

The black-and-white OHP sheet 101b of this embodiment
Has no mark at the tip as shown in FIG.
Further, the antistatic material 402 is simply applied to both sides of the PET resin 401.

The OHP sheet 10 without such a resin layer
1b (even if a sufficient amount of heat is applied), as shown in FIG.
Even if the magenta toner 05 and the magenta toner 506 melt, a clear red color (red) 504 is not projected on the screen 503.

The reason is that the black and white OHP sheet 101b does not have a resin layer, so that the fused toner 505 and 506 are
This is because the surface of the sheet 101b is not smooth, and light is irregularly reflected on the surface.

For an image of the above-mentioned level in which a clear image cannot be obtained, it is much more advantageous to output the image in the monochrome print mode in terms of energy consumption and speedup.

As described above, when the user selects a black-and-white OHP sheet and prints a color image, printing is automatically performed under the same fixing conditions as plain paper.

The fixing conditions of this embodiment are the same as those of the plain paper of the first embodiment. That is, fixing temperature = 157 to 177 ° C. conveyance and fixing speed = 10
0 mm / sec. It is.

When a black-and-white OHP sheet is used under these fixing conditions, a color image can be printed under advantageous conditions in terms of speed and energy saving.

To summarize the contents of the present invention described above,
As shown in FIG. That is, output in the color mode is color data only when an OHP sheet for color is used, and in all other cases, output is in the monochrome mode. As shown in Table 1 above, the fixing condition (1) is adopted in the black and white mode, and the fixing condition (2) or (3) is adopted in the color mode.

As described above, in the case of a black-and-white OHP sheet or a black-and-white only image pattern, the same image forming conditions as those of plain paper as a transfer material, that is, the speed and the fixing temperature can be efficiently controlled, and a clear image is formed on the OHP sheet. Is obtained.

[0059]

As is apparent from the above description, according to the present invention, when the transfer material is a black-and-white OHP sheet, or when an image is formed using only black-and-white image data, the type of the transfer material is limited. Regardless, by fixing under the same fixing conditions as plain paper, a reduction in power consumption and an increase in fixing speed can be achieved, and thus the fixing step can be performed efficiently,
And a clear image can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a paper feeding system of a color image forming apparatus according to the present invention.

FIG. 2 is a plan view of a color OHP sheet.

FIG. 3 is a plan view of a black-and-white OHP sheet.

FIG. 4 is a cross-sectional view showing a state in which a color image on a color OHP sheet is projected on a screen in the first embodiment.

FIG. 5 is a cross-sectional view showing a state in which a black and white image on a color OHP sheet is projected on a screen in the first embodiment.

FIG. 6 is a cross-sectional view illustrating a black-and-white OHP sheet according to a second embodiment.

FIG. 7 is a cross-sectional view illustrating a state in which a color image on a black-and-white OHP sheet is projected on a screen according to a third embodiment.

FIG. 8 is an explanatory diagram for comparatively explaining Examples 1 to 3.

FIG. 9 is a configuration diagram illustrating an example of a conventional color image forming apparatus.

FIG. 10 is a configuration diagram illustrating a developing device of the color image forming apparatus of FIG. 9;

11 is a configuration diagram illustrating a fixing device of the color image forming apparatus of FIG. 9;

[Explanation of symbols]

25 Fixing device 101 Transfer material 101a OHP sheet for color 101b OHP sheet for black and white 105 Transfer material tip sensor (OHP sheet detecting means)

Continued on the front page (72) Inventor Takao Kume 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (2)

[Claims] 1. A fixing device for fixing a developed image by heating or pressing a transfer material on which a developed image is formed, a control unit for controlling a transfer material conveying speed or a heating temperature of the fixing device, and A color image forming apparatus having an OHP sheet detecting means for detecting whether an OHP sheet or a black-and-white OHP sheet is used, wherein when the transfer material is a black-and-white OHP sheet, fixing is performed under the same fixing conditions as plain paper. Color image forming apparatus. 2. A fixing device for fixing a developed image by heating or pressing a transfer material on which a developed image is formed, a control unit for controlling a transfer material conveying speed or a heating temperature of the fixing device, and When an image is formed using only black and white image data in a color image forming apparatus having an OHP sheet detecting unit for detecting whether the sheet is an OHP sheet for black and white or an OHP sheet for black and white, regardless of the type of transfer material, A color image forming apparatus, wherein fixing is performed under the same fixing conditions as described above.