JPH03211576A - Toner fixing mechanism - Google Patents

Abstract

PURPOSE:To improve the fixing ability of a color toner image and to enhance surface gloss by providing a near infrared lamp fixing device which irradiates with near infrared light so that the fixed color toner image on a recording paper may be heated and fixed again on the recording paper ejection side of a heating roller. CONSTITUTION:The near infrared lamp fixing device 32 is for heating and fixing the toner image fixed by being heated and pressurized by the heating roller 17 again and is provided on the paper ejection side of the heating roller 17. The recording paper where fixation is completed is guided by a paper guide 33 to the underside of the fixing device 32, where the light from a lamp 37 is reflected to the recording paper by a reflector 36 so as to perform the fixation. Furthermore, as a fixing stage progresses, the glossiness is increased on the surface of the toner image and the recording paper is ejected to a paper tray by an ejection roller 35. Thus, a toner fixing mechanism where the fixing ability of the color toner image is improved and the surface gloss is enhanced is obtained.

Description

[Detailed Description of the Invention] [Summary] Regarding a toner fixing mechanism incorporated in an electrostatic recording device that uses color toner as a recording medium, the present invention aims to improve the fixability of color toner images and increase the glossiness of the surface. It is equipped with a heat roller that has an elastic layer on the surface of the recording paper and fixes the color toner image on the surface of the recording paper by pressing against the surface of the recording paper that is conveyed after transfer, and is incorporated into an electrostatic recording device that uses color toner as a recording medium. In the toner fixing mechanism, a near-infrared lamp fixing device is provided on the recording paper ejection side of the heat roller for irradiating near-infrared light so as to heat and fix again the color toner image on the recording paper that has been fixed by the heat roller. composition.

[Industrial application field]

The present invention relates to a toner fixing mechanism incorporated in an electrostatic recording device that uses color toner as a recording medium.

As is well known, the image process of an electrophotographic recording device (electrostatic recording device) involves an electrostatic latent image forming process.

Includes electrostatic latent image development processes, transfer processes, and fusing processes. The electrostatic latent image formation process involves optically projecting an image onto a photoreceptor drum or belt, or a dielectric drum.

An electrostatic latent image is formed by applying a charge on the film. In the electrostatic latent image development process, the electrostatic latent image is developed by electrostatically depositing toner as a recording medium on the electrostatic latent image thus formed. The toner used for development is transferred to the recording paper in a transfer process, and then the transferred toner is fixed to the recording paper in a fixing process. As methods for fixing transferred toner, there are known pressure fixing methods, flash fixing methods, heat fixing methods, etc., and the toner fixing mechanism differs depending on which fixing method is adopted.

In particular, OA equipment such as printers and copiers that use electrophotographic recording methods are required to save power, be smaller, and shorten the warm-up time.In addition, in color output, toner fixability is required. However, toner fixing mechanisms that employ a pressure fixing method and a flash fixing method cannot meet these demands. This is due to the following reason.

A toner fixing mechanism employing a pressure fixing method has the advantage of very low power consumption, no warm-up time, and simple structure. However, poor fixing performance has been pointed out as a drawback when fixing powder toner using a pressure fixing method. In order to improve the poor fixing properties of this powder toner, while increasing the linear pressure between the pressure rollers to 20 to 40 kg/cm,
A method has also been proposed in which coated paper is used as the recording paper and powder toner is forced into the coating material. However, with this method, the high fixing pressure causes wrinkles on the recording paper, and the fibers of the recording paper are crushed, resulting in gloss.
Furthermore, coated paper is not adopted because it does not meet market needs, and the biggest drawback in color output is that the color of the underlying toner does not reach the surface.

In addition, in the case of a toner fixing mechanism that uses a flash fixing method, no warm-up time is required, but the power consumption is extremely high (in addition, the size must be increased due to smoke and odor removal equipment, and color When toner is used as a recording medium, it is full.

For example, colors such as yellow, which transmit most of the wavelength of the light emitted from the light source of the flash lamp without absorbing it, will not be fixed.

On the other hand, in the case of a toner fixing mechanism that uses a thermal fixing method, a heat roller with a built-in heater is used, but this heat roller requires time to warm up, that is, warm-up time, and the power consumption of the heater is large. It has the following drawback. Further, when multiple layers of color toner are used for color expression, and when outputting at high speed, more power is required than when only black toner is used in the past, and control of the heat roller surface temperature becomes important. However, in color output, the surface of the toner in the recorded area becomes smooth and the brightness decreases.

This color constant fixing method is attracting attention in color image output because it is easy to expand the color reproduction range by improving saturation.

[Conventional technology]

Among color recording apparatuses of this type, there is one in which the leading edge of a recording paper or the like is clamped by a chuck and the recording paper is conveyed under each photoreceptor drum.

FIG. 8 shows an outline of the structure of a color recording apparatus of this type.

This device has four photoreceptor drums la and lb.

A process unit Pi centered on lc and ld, respectively.
, P2. P3. P4, a recording paper conveyance system 7, and a fixing unit 13. The process unit 1-Pi includes a charger 2a, an exposure optical system 3a, and an exposure optical system 3a around the photoreceptor drum 1a.
A developing device 4a and a transfer device 5a.

A cleaner 6a is provided. Other process units have similar configurations, 2b, 2c, 2d are chargers, 3b, 3
c, 3d are exposure optical systems, 4b, 4c, 4d are developing devices, 5b
, 5c, 5d are transfer devices, and 6b.

6c and 6d are cleaners. The developing devices 4a to 4d of each process unit contain developers of different colors. The developing devices 4a, 4b, and 4c contain Y (yellow), the three primary colors necessary for color recording.

M (magenta) and C (cyan) are used, respectively, and BK (black) is used for no correction in the developing device 4d. The recording paper conveyance system 7 includes a paper cassette 8. Standby roller 9. Chuck conveyance belt 10, recording paper conveyance belt 1
la-11C, and a paper tray 12.

The belts 10 are disposed on both sides in the width direction of the recording paper being conveyed, and are passed around pulleys 14 and 15. This belt 1
0 has a plurality of recording paper chucks (not shown) attached in a predetermined arrangement. The pulley 15 is connected to a drive system (not shown) on the drive side.

Recording by this device is performed in the following steps.

During recording, the recording paper 16 stored in the paper cassette 8 is fed out onto the conveyance path by the standby roller 9, and at the same time, a latent image corresponding to a signal of each color is sequentially formed on each of the photoreceptor drums 10a to 10d. Latent image formation is performed by uniformly charging the surface of each photoreceptor drum 1a to 1d with a corresponding charger 2a to 2d, and exposing the charged surface to light using an exposure optical system 3a to 3d. These latent images are developed by developing devices 4a to 4d to become toner images of Y, M, C, and BK colors. On the other hand, part of the leading edge of the unfed recording paper 16 is clamped by the recording paper chuck, and the chuck transport bell) 10. Air suction type recording paper conveyance belt t-1
The photoreceptor drums 1a to llc pass under each of the photoreceptor drums 1a to 1d and are conveyed. At this time, each transfer device 5a to 5d
The toner images on the photosensitive drums 18 to 1d are transferred onto the recording paper 16 in an overlapping manner. After that, when the recording paper 16 passes through the fixing unit 13, the toner image is fixed, and the recording paper 16 that has been fixed is discharged onto the paper tray 12.

FIG. 9 shows the structure of a conventional toner fixing mechanism using a heat fixing method used in such an apparatus. In Figure 9, 17
18 is a backup roller that presses against the heat roller 17; 19 is a heater for heating the heat roller 17; 20a and 20b are each roller. 21 is a thermocouple, 22 is a paper claw that peels off the paper from the heat roller 17, 23 is a paper guide that guides the paper between the rollers, and 24 is the fixed paper that is removed to the outside. A guiding paper guide 25 is an oil for always uniformly applying oil to the surface of the heat roller 17.

26 is a side plate of the fixing device.

The operation of the toner fixing mechanism having such a structure is as follows.

The recording paper on which the toner image has been formed is conveyed from the right side in FIG. In the roller fixing section, the heat roller 17 is heated by a heater 19, this is detected by a thermocouple 21, and the surface temperature of the heat roller 17 is kept constant through a controller. After detecting that the surface of the heat roller 17 has reached a desired temperature, the recording paper on which the toner image is formed, which is conveyed from the right as described above, is passed between the heat roller 17 and the backup roller 18. At this time, the toner image on the recording paper is melted by the heat from the heat roller 17 and the pressure between the rollers, and is fixed and solidified by the temperature drop after passing between the rollers. In this case, since the elastic N17b is formed on the surface of the heat roller 17, the surface of the toner image is smoothed, and an image with good brightness and saturation and a wide color reproduction range can be obtained. Further, the oil application device 25 serves to prevent toner from adhering to the heat roller 17 when the recording paper carrying a toner image passes between the rollers. If oil is not applied to the heat roller 17, the surface of the image will be rough due to the offset to the heat roller 17, and the color of the image on the recording paper will also change because the toner on the surface is taken up by the heat roller 17.

[Problem to be solved by the invention]

In order to obtain a fixed image with a stable color reproduction range, the toner deposited in layers during transfer must be sufficiently dissolved. This is because the color surface created using toner is expressed by subtractive color mixture, and therefore, in the toner image after fixing, reflected light from the underlying toner layer must also appear on the surface. Furthermore, in order to widen the color reproduction range and obtain a glossy image like a photograph, it is necessary to make the surface of the toner image smoother after fixing.

Therefore, in the conventional fixing method described above, the heat roller 17
It is necessary to maintain the surface temperature of the toner at a constant temperature at which sufficient toner melting occurs. However, the heat roller 17 has
In order to improve the surface smoothness and properties of the toner-fixed image, as described above, an elastic layer 17b made of silicone rubber or the like having good mold releasability is provided on the surface of the raw tube 17a made of aluminum or the like. Linear pressure approximately 1.0-2.0kg
/Cl11, and has a certain contact width due to this pressure. By heating the recording paper passing through this area, the toner image is heated and melted, and the surface is further smoothed. The heat roller 1 is heated by the passage of the recording paper.
However, since the rubber of the elastic layer 17b has low thermal conductivity, even if the thermocouple 21 detects the surface temperature of the heat roller 17 and immediately activates the heater 19, the heat roller 17 It takes a considerable amount of time and power for the surface temperature to return to its original level, and the images printed on the recording paper produced by then will be defective. In order to overcome this drawback, it is possible to use a heater with a large capacity or reduce the paper feeding speed, but excessive heating of the roller can cause the elastic layer 17b on the surface of the roller to
In addition to reducing the life of the rubber of the roller,
Heat is transmitted through 7a, shortening the life of the roller support, such as a bearing, and reducing the paper feed speed cannot be adopted because it limits the specifications of the apparatus.

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner fixing mechanism that can improve the fixing properties of color toner images and increase the glossiness.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a heat roller that has an elastic layer on its surface and fixes the color toner image on the surface of the recording paper by pressing against the surface of the recording paper that is conveyed after the transfer. In a toner fixing mechanism incorporated in an electrostatic recording device that uses color toner as a medium, near-infrared rays are applied to the recording paper ejection side of the heat roller so as to heat and fix the color toner image on the recording paper that has been fixed by the heat roller again. The structure includes a near-infrared lamp fixing device that irradiates light.

[For production]

The recording paper that has been fixed by the heat roller is sent to a near-infrared lamp fixing device, where the toner image on the recording paper that has been fixed by the heat roller is heated and fixed again by near-infrared light. Here, the fixing process further progresses and the glossiness of the toner image surface also improves.

〔Example〕

The present invention will now be described in detail with reference to FIGS. 1 to 7.

FIG. 1 is a side view showing the structure of the toner fixing mechanism of this example.
In the figure, 31 is a side plate, 32 is a near-infrared lamp fixing device, and 33
．． 34 is a paper guide, and 35 is a discharge roller. Note that the same reference numerals are used for members that are common to the conventional one.

The near-infrared lamp fixing device 32 is for reheating and fixing the toner image fixed by heating and pressure by the heat roller 17, and is provided on the left side of the heat roller 17 (on the paper discharge side). The near-infrared lamp fixing device 3
2 is a reflection plate 36 and a lamp 37 that serves as a near-infrared light source.
It is equipped with

In the fixed roller fixing portion, conventional fixing is performed, so a description thereof will be omitted here. The recording paper that has been fixed is guided by a paper guide 33 and guided under the near-infrared lamp fixing device 32.

Here, the light from the lamp 37 is reflected onto the recording paper by the reflecting plate 36 to perform fixing. Here, the fixing process further progresses, the surface of the toner image becomes more glossy, and then the recording paper is discharged to the paper tray by the discharge roller 35. A paper guide 34 that guides the recording paper to the discharge roller 35 at the time of discharge is made low on the right side so that even if the leading edge of the recording paper exiting the paper guide 33 hangs down, the paper can be guided to the discharge roller 35.

The outline of the near-infrared lamp fixing device is shown in FIG. 1, but in detail, the near-infrared lamp fixing device 32A is a concentrating heating wire type as shown in FIG. 2 or a parallel heating wire type as shown in FIG. A near-infrared lamp fixing device 32B or the like is used. In these fixing devices, 38.39 is a lamp that emits near-infrared rays, 40.41 is a reflector that reflects near-infrared rays, 42°43 is a heat dissipation plate for the reflector 40.41, and 44
45 indicates reflected near-infrared light.

Next, the results of experiments examining the effects of this example are shown in FIGS. 4 and 5.

In this experiment, the one shown in FIG. 3 was used as the near-infrared lamp fixing section. Also, the rubber thickness of the elastic layer of the heat roller is 2.
0am, contact pressure with backup roller is linear pressure 1.5
kg/cm, and the heat roller surface temperature during fixing is 170°C1.The voltage applied to the near-infrared lamp fixing device is A.
This is ClooV.

Figure 4 shows the glossiness of the output light. The measurement of glossiness is
NlPP0N DENS) Performed by VGS-ID manufactured by IOKU, 60 according to JIS-Z8741-1983
Evaluation was made using a mirror surface. In the figure, the . is for the case where only heat roller fixing is used (conventional method), and the square mark is for the case where near-infrared lamp fixing is performed after heat roller fixing (in the case of the present invention). -The difference is not clear in the secondary colors (Y, M, C'), but in the secondary colors (B, G).

In B), it can be seen that the glossiness is improved with the near-infrared lamp fixation.

FIG. 5 shows the color reproduction range at this time. The spectral distribution measurement was carried out using CMS-100 model manufactured by Murakami Color Research Institute. In the figure, the range of the dotted line connecting the dots is the color reproduction range of heat roller fixing only, and the range of the solid line connecting the dots is the color reproduction range when near-infrared lamp fixing is added. The addition of near-infrared lamp fixation has expanded the color reproduction range, and in particular, the secondary colors (R, G, B), which are superimposed colors, have expanded outward. This indicates that near-infrared lamp fixing promoted toner melting and improved fixing performance.

In order to confirm the improvement in fixing performance, we conducted a bending test and a peeling test using adhesive tape, and found that when only heat roller fixation was used, the recording paper and toner image area were separated by bending the image area. However, when fixing with a near-infrared lamp, only the image of the folded part was removed even after bending, and there was no change in other parts. Further, in a tape peeling test, in the case of an image fixed only by a hot roller, the image density decreases by 10% after the tape is peeled off.

This is because a portion of the image is captured on the tape, exposing the white of the recording paper to the surface. On the other hand, in the case of 7 where near-infrared lamp fixing was performed, no toner image was left on the tape, and the fixing performance was 100%, indicating that near-infrared lamp fixing improved the fixing performance.

Incidentally, in business documents, figures and photographs are often intermixed between sentences, and it is desirable that the text be matte so that it is easy to read. However, in the normal fixing method, the selection of gloss or non-glossy is made on a page-by-page basis, and even the text on pages with images is glossy. As a result, glossy pages and non-glossy pages coexist in one document, making it extremely difficult to read.

The 6th gloss selection method that can solve this problem.
It is shown in Figure 7. The operation of configuration 1 of this method is as follows.

In FIG. 6, reference numeral 51 indicates a drive shaft which is supported by fixed parts (not shown) at both ends and rotates at all times, 52 is a rotating cam, 53 is a movable plate supported by a support member 54 via a pin 55, and 56 is a connection such as a wire. Member 57 is a shielding plate for near-infrared light, 58
is a roller, 59 is a support that guides the shielding plate 57 and supports the shaft of the roller 58, and 60 is a tension spring.

In addition, in FIG. 7 showing details of the main parts of FIG.
64 is a spring clutch, 65 is a spring stop for the spring clutch 64, and 66 is a solenoid. The spring 60 is provided between the support 59 and the shield plate 57, and the rotating cam 52 has a high portion 52a and a low portion 52b.

The operation of this gloss selection method is as follows.

As the drive shaft 51 rotates all the time, the gear 62 also rotates. When blocking near-infrared light, the rotary cam 52 is positioned so that the lower portion 52b is at the top, as shown by the dotted line in FIG. 6, and the movable plate 53 that engages with this is positioned at the position shown by the dotted line. Therefore, the shielding plate 57 is positioned as indicated by the dotted line and blocks the near-infrared light 44. When opening the shielding plate 57, a voltage is applied to the solenoid 66 to release the plunger of the solenoid 66 from the spring stopper 65.

As a result, the spring clutch 64 is disengaged, the rotation of the drive shaft 51 is transmitted to the rotating cam 52 via the transmission gear 62, and the rotating cam 52 rotates. When the spring clutch 64 starts rotating, the voltage to the solenoid 66 is cut off so that the plunger of the solenoid 66 engages with the spring stop 65 again. The spring stopper 65 engages with the solenoid 66 every half circumference.
That is, there are two positions per circumference, which are adjusted where the high part 52a of the rotary cam 52 faces upward or downward. Therefore, the rotating cam 52 rotates 180 degrees and becomes the state shown by the solid line. At this time, the high portion 52a of the rotary cam 52 engages with the movable plate 53, and the movable plate 53 is positioned at the position indicated by the solid line.
is driven against the biasing force of the spring 60, and is moved to the left in FIG. 6 and positioned as shown by the solid line. In this state, the near-infrared light 44 is not blocked, and the toner image is re-fixed as described above. After that, near-infrared light 44
When shutting off, the solenoid 66 is activated again.

As a result, the rotating cam 52 is positioned as indicated by the dotted line in FIG. 6, and the shielding plate 57 moves rightward to the position indicated by the dotted line to block near-infrared light.

Although FIG. 6 shows the case where the near-infrared lamp fixing device 32A is used, it goes without saying that this method is similarly applied to the case where the near-infrared lamp fixing device 32B is used.

In addition, as shown in FIG. 6, this system uses the drive shaft 51 as a common axis and the other parts are a unit. Multiple units can be installed vertically). By using this light selection method, it is possible to improve the glossiness of only a required portion within the same page, for example, a color toner image portion.

〔Effect of the invention〕

As described above, according to the present invention, by performing near-infrared lamp fixing after fixing with a conventional heat roller fixing device, it is possible to improve the fixability of a color toner image and increase the glossiness.

[Brief explanation of drawings]

FIG. 1 is a side view showing the structure of a toner fixing mechanism according to an embodiment of the present invention, FIG. 2 is a detailed view of the structure of a near-infrared lamp fixing device, and FIG. 3 is another near-infrared lamp fixing device. Figure 4 is the same, a diagram explaining the glossiness of the output color, Figure 5 is the same,
Figure 6 is a diagram explaining the output color reproduction range, Figure 6 is a diagram explaining the gloss selection method, Figure 7 is a perspective view showing details of the main parts of Figure 6, and Figure 8 is an outline of the structure of a conventional color recording device. FIG. 9 is a side view showing the structure of a conventional toner fixing mechanism, in which 17 is a heat roller, 17b is an elastic layer, and 32 is a near-infrared lamp fixing device. Detailed drawing of the near-infrared lamp fixing device of the embodiment of this research -
100 50 0 00 a'' Fig. 5 Fig. 6 A perspective view showing details of the main parts of Fig. 6 Fig. 7 A side view showing the structure of the conventional toner fixing!! mechanism Fig. 9

Claims (1)

[Scope of Claims] A heat roller (17) having an elastic layer (17b) on its surface and fixing the color toner image on the surface of the recording paper by pressing against the surface of the recording paper conveyed after transfer, In a toner fixing mechanism incorporated in an electrostatic recording device that uses color toner as a recording medium, the color toner image on the recording paper fixed by the heat roller (17) is re-attached to the recording paper ejection side of the heat roller (17). A toner fixing mechanism comprising a near-infrared lamp fixing device (32) that irradiates near-infrared light so as to heat and fix the toner.