JP2003173122A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the wait time and to save energy in the case where the end part of a fixing roller is made large in wall thickness as a countermeasure for the prevention of temperature rise at a paper non-feeding part in a thin wall thickness fixing roller. <P>SOLUTION: An image is outputted in the order of smaller width of an image area in the longitudinal direction in the case of recording several images in the image recording means of an image forming apparatus so as to shorten the wait time such as start in a morning when the thickness of the end part is made large as compared with that of a center part in the thin wall thickness fixing roller. <P>COPYRIGHT: (C)2003,JPO

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, as an image forming apparatus, image exposure corresponding to an original image or an input image signal is performed on the surface of an image carrier uniformly charged by a charging means, and the surface of the image carrier is exposed. An electrostatic latent image is formed on the electrostatic latent image, the electrostatic latent image is developed into a toner image by a developing unit, the toner image is transferred to a transfer material by a transfer unit, and the toner image on the transfer material is fixed by a fixing unit. There are electrophotographic copying machines and printers that output images.

FIG. 8 shows a conventional image forming apparatus having a fixing device using a core metal thinning fixing roller. In the apparatus shown in FIG. 8, a primary charger 9 as a charging step for charging the image bearing member, which is arranged around each of the photosensitive drums 2 serving as the image bearing member, and the charged image bearing member are imaged. A developer image is formed on the photosensitive drum 2 by a laser scanner 1 as an exposure step of exposing according to information, and a developing device 3 as a developing step of visualizing the exposed portion with a toner image. Is transferred onto the recording material 11 by the transfer device 5 arranged opposite to the photosensitive drum 2. On the other hand, the toner remaining on the photosensitive drum 2 after the transfer is cleaned by the cleaning device 7
The developer image collected from the photosensitive drum 2 and transferred onto the recording material passes through the conveyance guide 12 together with the recording material, and is fixed by the fixing device 10.

FIG. 9 is an enlarged sectional view of the fixing device 10. In the fixing device 10, a pair of rollers are arranged in pressure contact with each other by a pressing means (not shown), and the fixing is performed by heating the rollers by a halogen heater 24 which is a heating means. Further, an entrance guide 23 is arranged in front of the pair of rollers, and the recording material enters the roller pair along the entrance guide 23. The roller pair is composed of a fixing roller 21 and a pressure roller 22. In the fixing roller 21, a silicon rubber layer 21B and a fluororesin layer 21C are formed on the outer surface of a hollow aluminum cored bar 21A. A halogen heater 24 is provided. A silicone oil coating / cleaning member 25 is disposed above the fixing roller 21 and is pressed against the fixing roller 21 by a pressing roller 26. Further, the pressure roller 22 has a structure in which an elastic body layer 22B made of, for example, silicon rubber and a fluororesin layer 22C are formed around a core metal 22A.

FIG. 10 is a sectional view of a conventional cored bar thinning fixing roller portion used in the fixing device 10. The inner diameter 27 of the support portion 26 for thinning the core metal and preventing heat radiation.
Then, a difference occurs between the inner diameter 28 of the fixing roller portion forming the nip with the pressure roller, and as a result, a step 29 is formed on the inner surface.

The reason why the core metal is thinned is that when a heater having the same performance as the roller and a fixing roller made of the same material are used, the heat capacity of the roller decreases as the roller thickness (inner / outer diameter difference) decreases. Since the amount of accumulated heat can be reduced, the time required for the roller surface to reach the target temperature is shortened, power consumption can be suppressed, and the material cost for the cored bar can be reduced.

Further, in normal image formation, when an image signal for image formation is input, energization of the heater 10 is started, and after a predetermined time (hereinafter referred to as start-up time) or the surface temperature of the heating roller 11 is predetermined. The control is performed such that the image forming operation is started after the temperature (hereinafter, referred to as print start temperature) is reached.

Further, in an image forming apparatus which has an input path of a digital image signal and an image signal storage means for storing the digital image signal, and which forms an image corresponding to the digital image signal, immediately after the power is turned on. When a plurality of image signals are input, the formation of the plurality of images is performed in the order in which they are input to the apparatus.

[0009]

However, when a transfer material (hereinafter referred to as small size paper) having a width smaller than the image forming width is continuously fed when using a thin fixing roller and a pressure roller, the transfer occurs. Phenomenon in which the surface temperature of the fixing roller and the pressure roller rises compared to the paper passing portion because the heat energy is taken away by the transfer material in the paper passing portion of the material, but not in the non-paper passing portion. This is called a non-sheet passing portion temperature rise) and is taken up as a serious problem when a thin roller is used. As a means for solving the problem, a method of thickening the end portion of the fixing roller or the pressure roller by a predetermined length can be considered. However, as an adverse effect of thickening the end portion, at the time of starting up the image forming apparatus in the morning, heat energy is required as compared with a roller that is uniformly thin, and the startup time is evenly thin. The problem is that it is longer than a certain roller.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an input path of a digital image signal including information on the type of transfer material to be recorded, and an input path from the input path. An image signal storage means for storing a digital image signal, a laser beam output means for outputting a laser beam emitted in response to the digital image signal, and a laser beam output by the laser beam output means for uniform charging by a charging means. An electrostatic latent image forming means for scanning the surface of the charged image carrier to form an electrostatic latent image, and a developing means for developing the electrostatic latent image formed on the surface of the image carrier into a toner image. And transfer means for transferring the toner image onto a transfer material,
At least the fixing roller or the pressure roller is heated by an internal heating member, a step exists between the inner surface of the flange portion and the inner surface of the nip portion on the inner surface of the cored bar of the heated roller, and the surface temperature of either roller. A fixing device having a temperature detecting means for detecting a transfer material, a transfer material accommodating means having a plurality of transfer material supply cassettes for accommodating various kinds of transfer materials, and each of the transfer material accommodating cassettes accommodated A transfer material recognizing means for recognizing the size of the transfer material, and a cassette selecting means for selecting a transfer material supply cassette for supplying the transfer material based on the recognition result of the transfer material size recognizing means forming the digital image signal. In the image forming apparatus having
When a plurality of images are stored in the image signal storage means, the image formation of the plurality of images is performed based on the type of transfer material forming the digital image signal according to the temperature of the temperature detection means. Characterized by determining the order.

Based on the above construction, in an image forming apparatus having a fixing device using a fixing roller or a pressure roller whose portion except a part of the end is thin, a plurality of images are stored in the image signal storage means. In this case, the order in which the images of the plurality of images are formed is determined based on the size of the transfer material forming the image, and the image formation can be started from the transfer material of a small size. Can be shortened and waste of electric power can be prevented.

[0012]

DETAILED DESCRIPTION OF THE INVENTION

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

First Embodiment (1) Image Forming Apparatus FIG. 1 is a schematic configuration diagram showing an embodiment of the image forming apparatus of the present invention.

In the figure, 2 is a rotating drum-shaped image bearing member, the surface of which is uniformly charged by the primary charging device 9. Then, an electrostatic latent image is formed by irradiating the surface of the image carrier 2 uniformly charged by the primary charging device 9 with the image exposure 13 corresponding to the image signal. Here, the image signal is an image signal input from the computer 1-a via the input path 1-b and stored in the image signal storage means 1-c, and the image exposure 13 corresponds to the image signal. Laser beam output means 1-d for outputting the emitted laser beam
Made by. Here, the image signal includes information on the image size and the size of the transfer material to be recorded.
After the electrostatic latent image is developed into a toner image by the developing device 3, the toner image is transferred to the transfer material 11 such as copy paper by the transfer charging device 5. Here, the transfer material 11 is stored in the paper feed cassettes 41 and 42. Paper feed cassette 41, 4
2 is provided with a paper type changeover switch (not shown), and the size (for example, A4, A4R, B5, B5R, A3, etc.) of the transfer material stored in each paper feed cassette is not shown in the image forming apparatus. The CPU controlling the operation of can be discriminated. The CPU selects a paper feed cassette that supplies the transfer material to the image forming unit in accordance with the image size information included in the image signal and the paper type changeover switch. The transfer material 11 on which the toner image is transferred is guided by the guide 12
The toner image is fixed by the fixing device 10 and then discharged as an output image to the paper discharge tray.

(Fixing Device) FIG. 2 is a diagram of a fixing device showing Embodiment 1 of the present invention, and FIG. 3 is a longitudinal sectional view of the fixing roller used in FIG. A halogen heater 31 is arranged as the heater. The same parts as those of the conventional device shown above are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the case where the number of heaters is 1 is shown, but the same thing can be said even when the number of heaters is 2 or more.

(1) As shown in FIG. 3, points P1 and P2 of 70 mm are formed inward from both sides of the roller end on the inner surface of the fixing roller.
The fixing roller and the apexes Q1 and Q2 of the inner surface of the support portion coupling point are linearly connected 360 degrees in the circumferential direction, and the resulting space V1 between the flat surface and the wall of the core metal is the core metal material. By filling with aluminum, the inner surface of the fixing roller whose core was thinned was smoothed.

In addition to aluminum, the core metal material is preferably iron or the like having high thermal conductivity, and the material for the thickness may be the same as or different from the core metal material. .

The value of 70 mm is A4R (width 210 m
When the sheet is continuously fed in m), the width of the entire A4R area should correspond to the thin portion of the roller. Therefore, an example of the relationship between each thickness and the length in the longitudinal direction is as shown in FIG. Since this is an example, it is desirable to change the internal wall thickness in consideration of a transfer material that is frequently used.

Although a method of providing a step at the end as shown in FIG. 4 may be considered, in such a case, the tip of the heater may be blocked by the step when the heater is passed through the cylinder during production. As a result, the heater may be damaged or the like. Therefore, considering productivity, it is preferable to set on the slope as in the present invention.

In this way, by smoothing the stepped portion on the inner surface of the core metal of the fixing roller, when the heater is mounted inside the fixing roller, the phenomenon of being caught by the step on the inner surface and the heater hitting the stepped portion. It is possible to prevent the heater from being damaged.

(2) As shown in FIG. 5, 70 mm points P1 and P2 are formed inward from both sides of the roller end on the inner surface of the fixing roller.
The curving of the apexes Q1 and Q2 of the inner surface of the fixing roller and the connecting point of the supporting portion is performed 360 degrees in the circumferential direction, and the resulting space V2 between the flat surface and the wall of the core metal is the core metal material. By filling with aluminum, the inner surface of the fixing roller whose core was thinned was smoothed.

In addition to aluminum, the core metal material preferably has high thermal conductivity such as iron, and the material for the thickness may be the same as or different from the core metal material. .

The value of 70 mm is A4R (width 210 m
When the sheet is continuously fed in m), the width of the entire A4R area should correspond to the thin portion of the roller. Therefore, an example of the relationship between each thickness and the length in the longitudinal direction is as shown in FIG. Since this is an example, it is desirable to change the internal wall thickness in consideration of a transfer material that is frequently used.

Although a method of providing a step at the end as shown in FIG. 4 may be considered, in such a case, the tip of the heater may be blocked by the step when the heater is passed through the cylinder during production. As a result, the heater may be damaged or the like. Therefore, considering productivity, it is preferable to set on the slope as in the present invention.

In this way, by smoothing the stepped portion on the inner surface of the core metal of the fixing roller, when the heater is mounted inside the fixing roller, the phenomenon of being caught by the step on the inner surface and the heater hitting the stepped portion It is possible to prevent the heater from being damaged.

(Non-Paper Passage Temperature Elevation) Comparative data on the temperature rise of the non-paper passage portion of a roller having a heater as a heating member will be described.

The condition is that the process speed is 300 mm / s.
Table 1 shows the temperatures converged when the ec and A4R transfer materials were continuously fed.

[0029]

[Table 1]

The temperature measuring position is 20 m from the end of the roller.
The temperature at the position of m is measured, and that portion is of course the non-sheet passing area.

The temperature was compared by using a thin roller having a surface of 3 mm, a roller having a V1 shape (FIG. 3), and a roller having a V2 shape (FIG. 5). Normally, the process speed is 300mm
In the / sec class, the wall thickness was around 10 mm, so a wall thickness of 3 mm is sufficiently thin.

From the results shown in Table 1, the change in the temperature rise of the non-sheet passing area is
The temperature increased in the order of no end special shape>V2> V1. A possible cause of this is a difference in heat capacity of the non-sheet passing portion. Comparing the heat capacities of the end portions, there is no special shape of the end portions>V2> V1, which is of course proportional to the total volume of the end portions, and there is no doubt.

From the above, it has been found that the temperature rise in the non-sheet passing portion can be reduced by making the end portion into a special shape.

(The rising characteristics of the surface temperature of the fixing roller in the morning) It has been clarified from the above that the improvement of the shape of the end portion is effective in raising the temperature of the non-sheet passing portion, but in consideration of the optimization of the shape. The rising characteristics of the fixing roller surface temperature in the morning must be taken into consideration. Therefore, the rise of the first temperature in the morning was compared for a thin roller having an entire surface of 0.7 mm, a roller having a V1 shape (FIG. 3), and a roller having a V2 shape (FIG. 5) under a temperature condition of 20 ° C. The result is shown in FIG. For the power application, a single heater of 1200 W was used.

The measuring position is 2 mm, which is 20 mm from the center and the end.
Points were measured for each roller.

From these results, it can be seen that the portion having a special shape at the end has a large heat capacity, and thus the rising in the morning is delayed. Further, comparing V1 and V2, the volume of V1 is larger and the heat capacity is larger, and as a result, the rise time is delayed.

Further, in the case of an ordinary roller, the rising time at the end portion is longer than that at the central portion, but the cause is that the end portion is hollow because the heater is passed therethrough. It is probable that the rise time was longer because the heat escaped from the part. The same applies to the other two rollers.

(Image Output Sequence) In the image forming apparatus having the above configuration, conventionally, when the power source of the image forming apparatus is turned on in the morning, the temperature detecting means such as the thermistor is heated at two places of the central portion and the end portion. The fixing roller or the pressure roller provided with the means is in contact with each other, and when the detected temperature reaches a predetermined temperature, image formation is possible. In this embodiment, the temperature is 200 ° C.

An image signal storage means for storing a digital image signal input path for recording an image to be output and a digital image signal input from the input path until a predetermined temperature is reached (called a wait time). Stocked by

Next, in the image forming apparatus of this embodiment,
The image forming operation characteristic of the present invention will be described in comparison with the image forming operation of the conventional image forming apparatus.

A series of image signals A1, A2, ..., A5 are input to the image forming apparatus during the wait time, and a few seconds after that, a series of image signals B1, B2 ,. . In this embodiment, the transfer material size information included in the image signals A1, A2, ..., A5 is A3 size information, and the image signals B1, B2 ,.
It is assumed that the transfer material information included in 5 is A4 size information.

The image forming operation of this embodiment will be described with reference to the sequence diagram of FIG.

The transfer material on which the image signals A1, A2, ..., A5 are recorded is A3 size, and the image signals B1, B2 ,.
When the transfer material on which is recorded is A4 size, when the temperature detected by the temperature detecting means in the central portion reaches 200 ° C., image formation of A4 size image signals B1, B2, ... ). When these image formations are completed, the surface temperature of the heating roller 11 is almost 2 degrees.
Since it has reached 00 ° C, the image signals A1 and A
, ..., A5 image formation is performed. When the end shape is V2, the wait time is 110 seconds because it is until the temperature of the central part reaches 200 ° C. On the other hand, in the past, it took 185 seconds because the weight had to be reached until the temperature of the end portion reached 200 ° C.

In this embodiment, the state after the power was turned on in the morning was explained, but in the case of the standby state in which the surface temperature of the heating roller is set lower than the surface temperature at the time of image formation in order to save energy (hereinafter, , Called power saving mode).

Further, it is apparent that the same effect can be obtained from the conventional case when the power supply to the heater is stopped in the standby state (hereinafter referred to as the sleep mode) for further energy saving.

From the above, it is possible to reduce the way and time with this configuration, and as a result,
We were able to efficiently utilize the power consumed during the waiting time.

[0047]

As described above, according to the present invention,
When a plurality of images are stored in the image signal storage means, the order in which the images are formed is determined based on the size of the transfer material forming the image so that the image recorded on the transfer material that is easily fixed Image formation can be started, wait time can be shortened, and power consumption can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing an outline of a configuration of an image forming apparatus according to the present invention.

FIG. 2 is a sectional view of a fixing device according to the present exemplary embodiment.

FIG. 3 is a sectional view of a heat roller according to the present embodiment (V
1).

FIG. 4 is a diagram showing an example of a cross-sectional view of a heat roller that can be considered from a conventional example.

FIG. 5 is a sectional view of a heat roller according to the present embodiment (V
2).

FIG. 6 is a diagram showing a rising time of the heat roller according to the present embodiment.

FIG. 7 is a flowchart according to this embodiment.

FIG. 8 is a sectional view showing an outline of a configuration of a conventional image forming apparatus.

FIG. 9 is a diagram showing a conventional image forming apparatus.

FIG. 10 is a diagram showing a conventional fixing roller.

[Explanation of symbols]

2 photosensitive drum 10 Fixing device 21 fixing roller 22 Pressure roller 23 Fixing entrance guide 24 halogen heater 25 Fixed Web 26 Pressing roller 32A halogen heater (main) 32B halogen heater (sub) 33 Flange 34 Heater installation guide

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H027 DA12 DC19 ED17 ED19 EE02                       EF01 EF09 FB02 FB05 FB07                       FB13 FD08 ZA07                 2H033 AA29 AA30 AA32 BB13 BB17                       CA03 CA04 CA07 CA17 CA35                 3J103 AA02 AA24 AA36 BA03 FA01                       FA20 GA57 GA58 GA66

Claims (3)

[Claims] 1. An input path for a digital image signal containing information on the size of a transfer material to be recorded, an image signal storage means for storing the digital image signal input from the input path, and corresponding to the digital image signal. A laser beam output means for outputting a laser beam to emit light, and a laser beam for outputting an electrostatic latent image by scanning the laser beam output by the laser beam output means on the surface of the image carrier uniformly charged by the charging means. An electrostatic latent image forming means, a developing means for developing the electrostatic latent image formed on the surface of the image carrier into a toner image,
A transfer means for transferring the toner image onto a transfer material, and at least a fixing roller or a pressure roller are heated by an internal heating member, and an inner surface of the core of the heated roller is provided between the inner surface of the flange portion and the inner surface of the nip portion. A fixing device having a step and having a temperature detecting means for detecting the surface temperature of one of the rollers; and a transfer material storing means having a plurality of transfer material supply cassettes for storing various kinds of transfer materials, Transfer material recognizing means for recognizing the size of each transfer material housed in each transfer material supply cassette and the transfer material are supplied based on the recognition result of the transfer material size recognizing means forming the digital image signal. In an image forming apparatus having a cassette selection unit for selecting a transfer material supply cassette, when a plurality of images are stored in the image signal storage unit, the temperature of the temperature detection unit is changed. Image forming apparatus and determines the order in which the image formation of the plurality of images based on the type of the transfer material to form said digital image signal in response to. 2. The fixing device, when smoothing a step generated on the inner surface of the fixing roller or the pressure roller, a point inside the end surface of the nip surface of the inner surface of the fixing roller or the pressure roller and the inner surface of the flange portion. Connecting the vertices of the linearly or curvedly or by connecting them in the entire circumferential direction, and filling the space between the plane and the wall of the cored bar with a cored bar member. The fixing device according to 1. 3. The image forming apparatus according to claim 1, wherein the digital image signal is a signal from a facsimile, a computer, a reader scanner, or the like.