JP2000242110A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily fix a toner image transferred to a recording medium by blowing warm air uniformly over a whole surface of the recording medium. SOLUTION: In this fixing device, a heat source 17 that carries out heat generating action, an air feeding means 18 that generates warm air by blowing air to the heat source 17, a carrying guide 31 where printing paper 14 is passed and a flow straightening means 1 that is installed in between the heat source 17 and the carrying guide 31 where plural through holes are formed to straighten out the blowing out direction of the warm air flown in from one side and feeding it to the carrying guide 31 from the other side are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus using an electrophotographic technique,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an orthogonal transfer type image forming apparatus that presses a toner image onto a print sheet and transfers the toner image in a direction orthogonal to a conveying direction of a print sheet as a recording medium.

[0002]

2. Description of the Related Art In recent years, toner-type image forming apparatuses capable of forming clear images with excellent resolution, such as laser printers, have become widespread. As an image forming apparatus of such a toner type, the applicant of the present invention has disclosed in Japanese Patent Application No. 7-328600 the orthogonal image forming apparatus in which a toner image carrier is moved in a direction orthogonal to a conveying direction of a printing paper to transfer a toner image. A transfer type image forming apparatus was proposed.

[0003] A conventional orthogonal transfer type image forming apparatus will be described below.

The orthogonal transfer type image forming apparatus has a closed loop belt-shaped toner image carrier, and is supported by a toner image carrier roller and a transfer opposing roller to rotate around. Around the toner image carrier, a toner image carrier cleaning means, a static eliminator, a charger, an exposure device, and a developing device are sequentially arranged in the rotation direction, and the toner is stored inside the developing device. . The printing paper is supported on a transfer plate, and is transported by a printing paper transport roller in a direction perpendicular to the rotation direction of the toner image carrier.

Next, the operation of the orthogonal transfer type image forming apparatus having the above-described configuration will be described.

When an image forming operation is instructed, the toner image carrier roller and the transfer opposing roller rotate, and the toner image carrier starts to rotate. After the surface of the toner image carrier is charged by the charger, an electrostatic latent image is formed on a portion charged by the laser light emitted from the exposure device.

When the developing roller of the developing device comes into contact with the toner image carrier, the electrostatic latent image is developed by the toner attached to the surface of the developing roller to form a toner image.

When the formation of the toner image is completed in this manner, the toner image carrier is pressed against the printing paper by the transfer opposing roller, and the toner image on the toner image carrier is transferred onto the printing paper.

When the transfer of the toner image is completed, the print paper transport roller rotates to transport the print paper on which the image is formed. Thereafter, the toner image is fixed on the printing paper by the fixing device, and is discharged to a discharge tray (not shown). on the other hand,
The toner remaining on the portion of the toner image carrier on which the toner image has been transferred is removed by the toner image carrier cleaning means, and then the charge on the toner image carrier is eliminated by the charge eliminator.

FIG. 7 is a perspective view showing the peripheral structure of a fixing device in a conventional orthogonal transfer type image forming apparatus.

As shown in FIG. 7, a fixing device 16 for fixing a toner image to printing paper includes a heat source 17 and a driving motor 1.
And a blowing means 18 such as a cross-flow fan which is driven to rotate by 9 and blows air to the heat source 17.
Then, the printing paper 14 is conveyed so as to traverse the flow path of the air starting from the blowing means 18 and passing through the heat source 17. On both sides of the air flow path, guide plates 20 having heat insulation properties and guiding the air from the blowing means 18 to the printing paper 14 are arranged.

Therefore, the air from the blowing means 18 is
As shown by a thick arrow in the drawing, the ink is heated by the heat source 17 and sprayed onto the printing paper 14 while the diffusion is prevented by the guide plate 20.

Downstream of the heat source 17, a temperature detecting means 30 for detecting the temperature of the hot air heated by the heat source 17 is provided. The heater is turned on / off based on the temperature of the hot air detected by the temperature detecting means 30 so that the temperature of the hot air becomes a predetermined temperature.

Below the fixing device 16, the fixing device 1
A conveyance guide 31 for passing the printing paper 14 is disposed between the conveyance guide 31 and the conveyance guide 31.

According to such a fixing device 16, the printing paper 14 to which the toner has been transferred is transported on the transport guide 31, and the toner is heated and melted by the hot air blown at this time to be fixed on the printing paper 14. You.

[0016]

However, the above-described fixing technique has the following problems.

That is, since the fixing device in the conventional image forming apparatus of the orthogonal transfer type only heats and melts by hot air, it is heated and pressed by a heat roller which has recently been used in many other image forming apparatuses. The heat capacity is smaller than that of the fixing device, and the fixing speed cannot be increased.

In addition, since the structure is such that the wind is blown to a heat source to generate hot air, and the hot air is blown to the printing paper, the hot air is not blown uniformly over the entire surface of the printing paper, and fixing unevenness occurs locally. I do.

Accordingly, an object of the present invention is to provide a fixing device that can quickly fix a toner image transferred to a recording medium.

Another object of the present invention is to provide a fixing device capable of uniformly blowing hot air onto the entire surface of a recording medium.

[0021]

In order to solve this problem, a fixing device according to the present invention transfers a toner image on a toner image carrier onto a recording medium by pressing the toner image onto the recording medium in a direction perpendicular to the conveying direction of the recording medium. A fixing device mounted on the image forming apparatus and fixing the toner image transferred to the recording medium to the recording medium, a heat source that performs a heat generation operation, and a blowing unit that generates warm air by blowing air to the heat source, A conveyance guide through which the recording medium passes, and a plurality of through-holes are provided between the heat source and the conveyance guide, where a plurality of through-holes are formed in which the blowing direction of the warm air flowing in from one side is made uniform and the hot air is discharged from the other side and sent to the conveyance guide. And a rectifying means.

This makes it possible to quickly fix the toner image transferred to the recording medium. Further, it becomes possible to blow warm air uniformly over the entire surface of the recording medium.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is mounted on an image forming apparatus for transferring a toner image on a toner image carrier by pressing the toner image onto a recording medium in a direction orthogonal to the conveying direction of the recording medium. A fixing device for fixing the toner image transferred to the recording medium to the recording medium, wherein a heat source for performing a heating operation, blowing means for blowing air to the heat source to generate warm air, and the recording medium passing therethrough A transport guide, a rectifying means installed between the heat source and the transport guide, having a plurality of through holes formed in which the blowing direction of the warm air flowing in from one side is made uniform, and the hot air is discharged from the other side and sent to the transport guide. The fixing device has a function of quickly fixing the toner image transferred to the recording medium. Also,
This has the effect that it becomes possible to blow hot air uniformly over the entire surface of the recording medium.

According to a second aspect of the present invention, in the first aspect of the present invention, the rectifying means is a fixing device made of a material having a high thermal conductivity, and the hot air having a higher temperature is supplied to the recording medium. To improve the fixing efficiency.

According to a third aspect of the present invention, in the first or second aspect, the temperature detecting means for detecting the temperature of the hot air from the rectifying means and the temperature detected by the temperature detecting means. The fixing device described above includes a heat source control unit that controls a heat generation amount of the heat source, and has an operation of enabling finer temperature control.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

FIG. 1 is a schematic view showing an image forming apparatus of an orthogonal transfer system according to an embodiment of the present invention, FIG. 2 is a perspective view showing a main part of the image forming apparatus of FIG. 1, and FIG. FIG. 4 is an explanatory view showing a transfer operation of the image transfer apparatus, FIG. 4 is a schematic view showing a structure of a fixing device attached to the image forming apparatus of FIG. 1, and FIG. 5 is a perspective view showing a rectifying unit used in the fixing device of FIG. FIG. 6 is a block diagram showing a control system of the fixing device shown in FIG.

As shown in FIG. 1, in the image forming apparatus of the orthogonal transfer system according to the present embodiment, the toner image carrier 4 which is a closed loop belt-shaped photosensitive member coated with an organic photoconductive material on its surface is used. The belt is tuned and supported by the transfer opposing roller 7, the toner image carrier roller 5, the displacement roller 6, and the sandwiching roller 8, and is rotated in the direction of arrow A.

Around the toner image carrier 4, a charger 9 for uniformly charging the surface of the toner image carrier 4 in the direction of its rotation, and an exposure light beam on the charged toner image carrier 4 An exposure device 13 for irradiating the latent image 13a to form an electrostatic latent image corresponding to image data, and applying toner to a latent image portion of the toner image carrier 4 formed by the exposure device 13 to visualize the electrostatic latent image Developing unit 10, a toner image carrier cleaning unit 11 for removing residual toner remaining on the toner image carrier 4 after transfer, and a static eliminator 12 for removing residual potential on the toner image carrier 4 are sequentially arranged. Have been.

The developing unit 10 contains a toner 10a, and a developing roller 10b for attaching the toner 10a to the electrostatic latent image formed on the toner image carrier 4.
Is provided.

A printing paper (recording medium) 14 is supported on a transfer plate 15, and the toner image carrier 4 is rotated by a printing paper transport roller 11 that transports the printing paper 14, as shown in FIG. The sheet is transported in a direction (arrow B direction) orthogonal to the direction (arrow A direction).

As shown in FIG. 4, a fixing device 16 for fixing the toner image 10c to the printing paper 14 is driven by a heat source 17 for generating heat and a driving motor (not shown). And a blowing means 18 such as a cross flow fan for blowing air. And printing paper 1
4 is conveyed so as to traverse the flow path of the air starting from the blowing means 18 and passing through the heat source 17.

On both sides of the air flow path, guide plates 20 having heat insulating properties and guiding the air from the blowing means 18 to the printing paper 14 are arranged.

The rectifying means 1 is provided downstream of the heat source 17 so as to be surrounded by the guide plate 20.

Therefore, the air from the blowing means 18 is
As shown by the arrow in the figure, while being prevented from being diffused by the guide plate 20, it is heated by the heat source 17 and then passes through the rectifying means 1 and is sprayed on the printing paper 14.

As the heat source 17, a light irradiation type such as a halogen lamp, a xenon lamp, a mercury lamp, and an infrared heater lamp, and a resistance heating type using a nichrome wire or the like are used.

Downstream of the rectifying means 1, a temperature detecting means 30 such as a thermistor for detecting the temperature of the hot air heated by the heat source 17 is provided. The heater is turned on / off based on the temperature of the hot air detected by the temperature detecting means 30 so that the temperature of the hot air becomes a predetermined temperature.

Below the fixing device 16, the fixing device 1
A conveyance guide 31 for passing the printing paper 14 is disposed between the conveyance guide 31 and the conveyance guide 31. In the present embodiment, the fixing device 1
6 and the conveyance guide 31 are shown as separate bodies, but the conveyance guide 31 may be included in the fixing device 16.

According to the fixing device 16, the printing paper 14 to which the toner has been transferred is transported on the transport guide 31, and the toner is heated and melted by the hot air blown at this time and is fixed on the printing paper 14. You. In addition, the blowing means 18
Is always on during the fixing operation.

The rectifying means 1 in the present embodiment is different from the rectifying means shown in FIG.
As shown in (1), it is composed of, for example, a honeycomb laminate. That is, in FIG. 5, the rectifying means 1 includes a flat plate 1a called a liner and a corrugated plate 1 called a corrugate.
b is superposed step by step. The rectifying means 1 is made of a material having a good thermal conductivity such as a metal such as aluminum.

According to such a rectifying means 1,
The warm air input from one side as indicated by arrows X and Y flows out from the other side as indicated by arrow Z.

Here, as shown in FIG. 5, even if the directions of the winds input to the rectifying means 1 are not uniform, and even if a part thereof is slightly Is blown out straight to the printing paper 14 in a straight line with the same blowing direction.

Note that the rectifying means 1 does not necessarily have to have a honeycomb structure, and a plurality of through holes are formed in which the blowing direction of the air flowing in from one side is made uniform and the air flows out from the other side and is sent to the printing paper 14. It should just be.

Next, a control system of the fixing device 16 will be described.

In FIG. 6, the MPU as the heat source control means
(Microprocessor unit) 21
2 to control the entire image forming apparatus while reading out the program incorporated therein. The blower 18 is controlled by the MPU 21 via the fan driver (drive circuit) 27 and the temperature of the heat source 17 is controlled via the heater driver (drive circuit) 23. Also,
The temperature of the warm air in the analog signal detected by the temperature detecting means 30 is converted into a digital signal by the A / D converter 29 and input to the MPU 21. Thereby, finer temperature control is performed.

Next, the operation of the orthogonal transfer type image forming apparatus having the above configuration will be described.

When the control section (not shown) of the image forming apparatus instructs the start of the image forming operation, the image data is written into the image data storage memory, and the toner image carrier roller driving means (not shown). Transfer opposing roller 7, toner image carrier roller 5, displacement roller 6, and nipping roller 8
Rotates, and the toner image carrier 4 starts to rotate in the direction of arrow A.

The surface of the toner image carrier 4 is charged, for example, to -600 V by the charger 9 in accordance with the content of the image to be formed.
After being uniformly charged to a certain degree, an electrostatic latent image is formed on the charged portion by the exposure light beam 13a emitted from the exposure unit 13 in accordance with data read from an image data storage memory (not shown). .

When the portion of the toner image carrier 4 where the electrostatic latent image is formed reaches the position of the developing device 10, the developing roller 10b disposed in the developing device 10 is driven by developing roller driving means (not shown). It rotates and comes into contact with the toner image carrier 4. As a result, the toner image carrier 4 is moved to the developing roller 10b.
The electrostatic latent image is developed by the toner 10a attached to the surface of the developing roller 10b while being moved while being nipped between the nipping roller 8 and the toner image 10c on the toner image carrier 4.
Is formed.

By such an operation, the toner image 1 in a range corresponding to the image forming area L of the printing paper 14 shown in FIG.
When 0c is formed on the toner image carrier 4, the transfer of the toner image 10c from the toner image carrier 4 onto the printing paper 14 is performed.

That is, the transfer of the toner image 10c is performed by first setting the tip p1 of the toner image 10c formed on the toner image carrier 4 to the end p2 of the image forming area of the printing paper 14.
When the position is substantially the same as the above, the rotations of the toner image carrier roller 5, the displacement roller 6, and the transfer opposing roller 7 are stopped, and the rotation of the toner image carrier 4 is stopped.

Next, the paper transport roller 11 is rotated by paper transport means (not shown), and the printing paper 14 is transferred in the direction of arrow B perpendicular to the rotation direction of the toner image carrier 4 as shown in FIG. It is transported to a predetermined position on the plate 15.

When the transfer of the printing paper 14 is completed, the transfer facing roller driving means (not shown) moves the transfer facing roller 7 from the transfer start position p3 to the transfer end position p4 in the direction of arrow C shown in FIG. And the displacement roller 6 moves in the direction of arrow D so as to keep the tension of the toner image carrier 4 constant with the movement of the transfer opposing roller 7.

During the parallel movement of the transfer opposing roller 7,
The toner image carrier 4 is sequentially pressed against the printing paper 14 by the transfer opposing roller 7. At this time, by applying a reverse bias to the toner image to the entire transfer plate 15, the toner image 10c on the toner image carrier 4 is attracted to the transfer plate 15 side, and the printing paper 14 on the transfer plate 15 Is transferred to

When the transfer of the toner image 10c is completed in this way, the printing paper conveying roller 11 rotates again, and the printing paper 14 is moved by a distance corresponding to the effective transfer width M of the toner image carrier 4 shown in FIG. Is transported in the direction of arrow B, and the toner image carrier 4 rotates.

Then, again, the leading end of the toner image 10 c on the toner image carrier 4 is moved to the image forming area L of the printing paper 14.
Is substantially the same as the end of the toner image 10c, the toner image 10c is transferred onto the printing paper 14 in the same manner as described above. At this time, the transfer opposing roller 7 moves from the previous transfer end position p4 in the direction opposite to the arrow C direction shown in FIG. 3, and moves in parallel along the printing paper 14 to the previous transfer start position p3.

After the transfer, the printing paper 14 is conveyed in the direction of arrow B by the same distance as the effective transfer width M shown in FIG. Further, the toner remaining on the portion of the toner image carrier 4 where the toner image 10c has been transferred is removed by the toner image carrier cleaning means 11, and thereafter, the charge on the toner image carrier 4 is eliminated by the charge eliminator 12. You.

As described above, the formation of the toner image 10 c on the toner image carrier 4 and the formation of the toner image 10
The transfer of c and the paper conveyance are repeated, and the printing paper 14 reaches the fixing device 16.

In the fixing device 16 shown in FIG. 4, when the printing operation starts, the blowing means 18 starts rotating.

Next, when the heat source 17 is energized and generates heat,
The wind sent by the blowing means 18 hits this and becomes hot air. This hot air is rectified by the rectification means 1 installed downstream of the heat source 17. The temperature of the rectified hot air is monitored by the temperature detecting means 30 and detected by the MPU 21. Then, it waits until the temperature of the hot air reaches a predetermined value.

When the temperature of the hot air reaches a predetermined value, the printing paper 1 on which the unfixed toner image 10c is placed as described above.
4 is conveyed to the fixing device 16. Then, the fixing device 16
The toner is melted by the warm air blown at the predetermined temperature, and solidifies until the printing paper 14 comes out of the fixing device 16 to complete the fixing.

Here, as described above, the rectifying means 1
Is composed of a honeycomb structure having good thermal conductivity in which a flat plate 1a and a corrugated plate 1b are superposed step by step.

Accordingly, the direction of the warm air is made uniform by passing through the rectifying means 1, and the warm air can be blown uniformly and uniformly over the entire surface of the printing paper 14. This allows
It is possible to improve fixing defects due to unevenness of hot air blowing.

The rectifying means 1 is made of a material having a good thermal conductivity, and has a very large surface area due to the honeycomb structure. Rectification means 1 in the same manner as
Has a uniform temperature, whereby the temperature of the wind coming out of the rectifying means 1 becomes uniform. In addition, since the rectifying means 1 has a predetermined heat capacity depending on the material, plate thickness, surface area, and the like, the entire system is prevented from being rapidly cooled by continuous paper passing or the like.

As a result, the hot air having a higher temperature
4, the toner image 10c transferred to the printing paper 14 can be quickly fixed.

It is necessary to optimize the heat capacity in accordance with the wattage of the heat source 17 and the air volume or speed of the blowing means 18. In other words, increasing the heat capacity has the effect of preventing the entire system from suddenly cooling due to continuous paper passing or the like.
6 has a disadvantage that the rise time is long. Further, since the rectifying means 1 having the honeycomb structure serves as a heat radiating plate for the heat source 17, the rectifying means 1 having a heat capacity that cannot reach the fixing temperature with respect to the wattage of the heat source 17 is meaningless. Therefore, the specifications of the device (heat source 17
It is necessary to determine the heat capacity of the honeycomb which is the rectifying means 1 in accordance with the wattage, the paper feeding speed, the fixing property, and the rise time of the apparatus.

For example, when the heat source 17 is 500 W,
8 is about 1.2 cubic m / min (wind speed about 6 m / min.
s), when the paper feed speed is 30 mm / s and the rise time is 30 seconds, the optimal heat capacity of the rectifying means 1 is made of aluminum, the thickness t = 0.1 mm, the corrugation pitch is 3.3 mm, and the corrugation height is 2. It is preferable that the honeycomb size is 1 mm and the honeycomb size has a volume of 8 cubic mm per watt. However, it should be noted that the outer wall of the fixing device 16 also has a heat capacity. Since the heat capacity has many parameters in this way, it is better to find out the optimum one by experiment.

As described above, according to the fixing device 16 of the present embodiment, the direction of the warm air is made uniform by the rectifying means 1, and the warm air is blown uniformly and uniformly over the entire surface of the printing paper 14. Becomes possible. Thereby, it is possible to improve the fixing failure due to the unevenness of the blowing of the warm air.

The rectifying means 1 is made of a material having good thermal conductivity and has a very large surface area due to the honeycomb structure, so that the rectifying means 1 has a uniform temperature and a predetermined heat capacity. As a result, hotter air having a higher temperature can be blown onto the printing paper 14, and the toner image 10 c transferred to the printing paper 14 can be quickly fixed.

[0070]

As described above, according to the present invention, it is possible to obtain an effective effect that the temperature of the rectifying unit becomes uniform and the toner image transferred to the recording medium can be quickly fixed. .

Further, according to the present invention, since the direction of the hot air is made uniform by the rectifying means, an effective effect is obtained that the hot air can be blown uniformly and evenly over the entire surface of the recording medium. .

If the rectifying means is made of a material having a good thermal conductivity, an effective effect of improving the fixing efficiency by blowing hotter air at a higher temperature on the recording medium can be obtained.

The provision of the temperature detecting means and the heat source controlling means has an advantageous effect that finer temperature control becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an image forming apparatus of an orthogonal transfer system according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a main part of the image forming apparatus of FIG. 1;

FIG. 3 is an explanatory diagram illustrating a transfer operation of the image transfer device of FIG. 1;

FIG. 4 is a schematic diagram illustrating a structure of a fixing device attached to the image forming apparatus of FIG. 1;

FIG. 5 is a perspective view showing a rectifying unit used in the fixing device of FIG. 4;

FIG. 6 is a block diagram showing a control system of the fixing device of FIG. 4;

FIG. 7 is a perspective view illustrating a peripheral structure of a fixing device in a conventional orthogonal transfer type image forming apparatus.

[Explanation of symbols]

 Reference Signs List 1 rectifying means 4 toner image carrier 10c toner image 14 printing paper (recording medium) 16 fixing device 17 heat source 18 blowing means 21 MPU (heat source control means) 30 temperature detecting means 31 transport guide

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadahiro Kugimaru 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. F term (reference) 2H027 DA12 EA12 EA15 JB12 JB13 JB19 JC08 2H032 AA14 BA18 BA23 2H033 AA03 AA20 BA12 BA25 BA31 BE02

Claims (3)

[Claims] An image forming apparatus which presses and transfers a toner image on a toner image carrier from a recording medium in a direction orthogonal to a conveying direction of the recording medium and transfers the toner image onto the recording medium; A fixing device for fixing the recording medium, a heat source performing a heating operation, blowing means for blowing air to the heat source to generate warm air, a conveyance guide through which the recording medium passes, the heat source and the conveyance And a rectifying means provided with a plurality of through-holes which are provided between the guide and the blow-out direction of the warm air flowing in from one side and flow out from the other side and sent to the transport guide. Fixing device. 2. The fixing device according to claim 1, wherein said rectifying means is made of a material having good thermal conductivity. A temperature detecting means for detecting a temperature of the hot air from the rectifying means; and a heat source controlling means for controlling a heat generation amount of the heat source based on the temperature detected by the temperature detecting means. The fixing device according to claim 1, wherein: