JPH07311506A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain nearly the same gloss without depending on the thickness and the gloss of recording material by detecting the thickness and the surface gloss of the recording material and setting a fixing condition in accordance with the detection result. CONSTITUTION:The thickness of the recording material is detected by a recording material thickness detecting means when a copy button is pressed down and the recording material is supplied, and the surface gloss of the recording material is succeedingly detected by a recording material surface gloss degree detecting means. A CPU being a controlling means makes a fixing speed varying means set an adequate fixing speed based on the matrix of an output value detected by the two detecting means. That is, since the surface gloss of the image is higher after fixing as the surface gloss is higher in the case of the recording material having the same thickness, the fixing speed is increased and fixing force is weakened, so that the surface gloss is lowered as the surface gloss of the recording material becomes higher. And, since the surface gloss of the image becomes higher as the thickness is decreased on the recording material having the same surface gloss, the fixing speed is increased as the thickness is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image having a heat fixing device for fixing an unfixed toner image by passing a recording material having an unfixed toner image between a fixing roller and a pressure roller which are in pressure contact with each other. The present invention relates to a forming apparatus, particularly a color image forming apparatus having a heat fixing device and a plurality of image forming means.

[0002]

2. Description of the Related Art As an example of the above-mentioned image forming apparatus, FIGS. 10 and 11 show a four-drum laser beam printer having a plurality of optical scanning means.

As shown in FIG. 10, the printer is an image forming means including a developing device and the like around an electrophotographic photosensitive member (hereinafter referred to as "photosensitive drum") which is a latent image carrier. Four image forming stations that are barrels are provided, and the image formed on each of the image forming stations on the photosensitive drum is a recording material such as paper (hereinafter referred to as a recording material) on a conveying unit that moves and passes adjacent to the photosensitive drum. , Simply paper).

Further, as shown in FIG. 11, the image forming stations Pa, Pb, Pc and Pd for forming images of magenta, cyan, yellow and black, respectively, have photosensitive drums 1a, 1b, 1c, respectively. 1d is arranged, and each photosensitive drum is rotatable in the arrow direction.
Further, around the photosensitive drums 1a, 1b, 1c, 1d, chargers 12a, 12b, 12c, 12d, developing devices 2a, 2b, 2c, 2d, and cleaners 4a, 4 are provided.
b, 4c, and 4d are sequentially arranged along the rotation direction of the photosensitive drum, and the transfer unit 3 is provided below each photosensitive drum.
Is provided. The transfer section 3 has a transfer belt 31 which is a recording material conveying means common to each image forming station, and transfer chargers 3a, 3b, 3c and 3d.

In the printer as described above, the paper P supplied from the paper feed cassette 61 which is the recording material supply means shown in FIG. 10 is supported on the transfer belt 31 and conveyed to each image forming station, and each of the above-mentioned respective The toner images of the respective colors formed on the photosensitive drum are sequentially transferred. When this transfer step is completed, the paper P is separated from the transfer belt 31 and is conveyed to the fixing device 5 by a conveyor belt 62 which is a recording material guide means.

As shown in detail in FIG. 12, the fixing device 5 includes a fixing roller 51 that is rotatably disposed, a pressure roller 52 that rotates while being in pressure contact with the fixing roller 51, and a release agent supply coating. It is configured to have a release agent applying device 53 as a means and roller cleaning devices 54 and 55.
Inside the fixing roller 51 and the pressure roller 52, heaters 56 and 57 such as halogen lamps are provided, respectively. Further, the thermistors 58 and 59 are arranged so as to come into contact with the fixing roller 51 and the pressure roller 52, respectively. By controlling the voltage to the heater 56 and the heater 57 via a temperature adjusting circuit, the fixing roller 51 and the fixing roller 51 are controlled. Also, the temperature of the surface of the pressure roller 52 is adjusted. In this state, when the paper is conveyed, the fixing roller 51 and the pressure roller 52 rotate at a constant speed, silicone oil is applied to the surface of the fixing roller 51 as a release agent, and the paper P is fixed to the fixing roller 51. When passing between the pressure rollers 52, the unfixed toner image on the surface of the paper is melted and fixed by being pressed and heated from both the front and back sides at a substantially constant pressure and temperature, and a full-color image is formed on the paper P. It The paper P on which the image is fixed is separated from the pressure roller 52 by the lower separation claw 68, and is discharged to the outside of the machine.

The fixing roller used in the above-mentioned fixing device is coated with a material such as a fluororesin or silicone rubber having a good releasing property, and having excellent heat resistance and abrasion resistance, to form an outer layer thereof. There is. For example, when the image forming apparatus is a color copying machine using an electrophotographic system and particularly attaches importance to image quality, the fixing roller 51 is often made of silicone rubber as an outer layer of the roller. .
This silicone rubber is slightly inferior to the fluororesin in releasability, but when silicone oil is applied as a release agent, the releasability is improved as compared with the fluororesin.

[0008]

However, the conventional image forming apparatus has the following problems. First, in a fixing device of a color copying machine, there are cases in which the fixability varies depending on the type of recording material on which an image is formed, which causes the glossiness of the image after fixing to differ. That is, when recording materials having different thicknesses are fixed by the fixing device under the same conditions, sufficient fixing is performed in the case of a thin recording material, and as a result, the image surface after fixing becomes smooth and gloss becomes high. In the case of a thick recording material, fixing is insufficient, and as a result, the image surface after fixing becomes rough and the gloss becomes low. Even for recording materials having the same thickness, the gloss after fixing also differs due to the difference in the glossiness (surface roughness) of the surface. That is, when a recording material having a high surface gloss (fine surface roughness) is fixed, the image surface after fixing becomes smooth and gloss is high, but the surface gloss is low (surface roughness is rough). ) When fixing the recording material, the image surface after fixing becomes rough and the gloss becomes low.

As described above, the optimum fixing condition differs depending on the thickness of the recording material and the gloss and roughness of the surface of the recording material. Therefore, under the same fixing condition, a difference occurs between the image gloss after fixing. Was there.

A first invention according to the present application provides an image forming apparatus which solves the above problems and can obtain almost the same gloss regardless of the thickness of the recording material and the gloss of the surface of the recording material. Is intended.

In addition to the above-mentioned object, the second invention of the present application adjusts the amount of heat applied to the recording material so that the recording material is almost independent of the thickness of the recording material and the gloss of the surface of the recording material. An object is to provide an image forming apparatus that can obtain the same gloss.

Further, in addition to the above-mentioned object, the third invention according to the present application adjusts the temperature applied to the recording material, so that the recording material is not affected by the thickness of the recording material and the gloss of the surface of the recording material.
An object of the present invention is to provide an image forming apparatus that can obtain almost the same gloss.

In addition to the above object, the fourth invention according to the present application adjusts the pressing force applied to the recording material, so that the recording material is not affected by the thickness of the recording material and the gloss of the surface of the recording material.
An object of the present invention is to provide an image forming apparatus that can obtain almost the same gloss.

[0014]

According to the first invention of the present application, the above object has a roller pair of a fixing roller and a pressure roller which are rotatably arranged while being pressed against each other. In an image forming apparatus equipped with a fixing device that presses and conveys a recording material having an unfixed image at a pressure contact portion formed by a roller pair to heat and fix the unfixed image on the recording material, The recording material thickness detecting means for detecting and the recording material surface gloss detecting means for detecting the surface gloss of the recording material are provided, and depending on the output values of the recording material thickness detecting means and the recording material surface gloss detecting means. It is achieved by having control means set to change the fixing conditions of the fixing device.

According to the second invention of the present application,
The above object is achieved by setting the fixing condition in the first invention to be a fixing speed.

Further, according to the third invention of the present application, the above-mentioned object is to set the fixing condition in the first invention as follows.
This is achieved by setting the fixing temperature.

According to the fourth invention of the present application,
The above object is achieved by setting the fixing condition in the first aspect of the present invention to a pressure applied between the fixing roller and the pressure roller.

[0018]

According to the first invention of the present application, before the recording material is conveyed to the fixing device, the thickness of the recording material is detected by the recording material thickness detecting means, and the surface gloss of the recording material is detected. The surface gloss of the recording material is detected by the means and the fixing condition is set according to the thickness and the gloss of the recording material. Therefore, when fixing is performed, the gloss is almost the same regardless of the thickness and the gloss of the recording material. To get

According to the second invention of the present application,
For recording materials of the same thickness, the higher the surface gloss, the greater the gloss of the image after fixing.Therefore, the higher the surface gloss of the recording material, the faster the fixing speed.
It weakens the fixing power and lowers the gloss. Further, even if the recording material has the same surface gloss, the thinner the thickness, the higher the image gloss after fixing. Therefore, when the thickness is thin, the fixing speed is increased to enhance the fixing power and enhance the gloss. Further, as the thickness increases, the fixing speed is slowed down to weaken the fixing power and weaken the gloss. Thus, according to the invention,
Almost the same gloss is obtained regardless of the thickness and surface gloss of the recording material.

According to the third invention of the present application, in the case of recording materials having the same thickness, the higher the surface gloss, the more
Lowering the fixing temperature weakens the fixing power and lowers the gloss. On the other hand, in the case of recording materials having the same surface gloss, the thicker the recording material is, the higher the fixing temperature is to increase the gloss. Thus, according to the present invention, almost the same gloss is obtained regardless of the thickness and surface gloss of the recording material.

Further, according to the fourth invention of the present application, in the case of recording materials having the same thickness, the higher the surface gloss, the weaker the pressing force to weaken the fixing force and the gloss. make low. Further, in the case of recording materials having the same surface gloss, the thicker the recording material, the stronger the pressurizing force and the higher the gloss. Thus, according to the present invention, almost the same gloss is obtained regardless of the thickness and surface gloss of the recording material.

[0022]

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

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a full-color copying machine of the present invention. The common parts with the conventional example shown in FIG.

As shown in FIG. 1, the apparatus of this embodiment is provided with a recording material thickness detecting means 15 and a recording material surface glossiness detecting means 16 in a paper feeding portion, and the fixing means shown in FIG. As shown in the flow chart of the condition change control, the thickness and surface gloss of the recording material are detected and the optimum fixing condition is set according to the detection.

FIG. 4 is a diagram showing the recording material thickness detecting means 15 in the apparatus of this embodiment. The recording material thickness detecting means 1 is shown in FIG.
Reference numeral 5 allows the upper roller 20a of the registration roller 19 to move up and down, and a spring member 21 to move the upper roller 20a.
It is set so that the upper roller 20a is moved up and down depending on the thickness of the recording material by pressing it toward the roller 20b which is a. The upper roller 20a is attached to one end of the upper roller 20a.
A clutch 22 for expanding and transmitting the amount of vertical movement of a is provided, and a paper thickness detector (potentiometer) 23 for detecting the paper thickness by the swing amount of the clutch 22 is attached.
The thickness of the recording material can be detected by arranging the recording material thickness detecting means 15 in the paper feeding section of FIG.

Further, FIG. 5 shows the measurement by the recording material surface glossiness detecting means 16 of the present embodiment by the method defined in JIS Z8741. That is, the measuring method is that a light beam having a specified opening angle is incident on the surface of the recording material at a specified incident angle, and a light beam having a specified opening angle reflected in the specular reflection direction is measured by a light receiver. In FIG. 5, the light flux emitted from the light source 108 passes through the lens 110 and is incident on the recording material P at an angle θ.
Is incident at. Then, the light beam reflected in the specular reflection direction is detected by the light receiver 109 through the lens 110. The surface gloss of the recording material can be detected by arranging the recording material surface glossiness detecting means in the paper feeding section of FIG. In all the embodiments of the present invention described below, the incident angle θ is 60
The surface gloss was measured at °.

In this embodiment, as shown in FIG.
First, when the copy button is pressed and the recording material is fed, the recording material thickness detecting means 15 detects the thickness of the recording material. Next, the recording material surface glossiness detecting means 16 detects the glossiness of the recording material surface. Then, in the CPU as the control means, the optimum fixing speed is set based on the fixing speed varying means (not shown) by the matrix of output values detected by these two detecting means as described later.

In this embodiment, the fixing roller 51,
A Si rubber roller is used as the pressure roller 52, and the applied pressure is 50
kgf, nip width 7.5 mm, plain paper (paper thickness 8
0 μm, surface gloss 5-10%), fixing temperature 1
It was fixed at 80 ° C. and a fixing speed of 135 mm / sec. As a result, the gloss of the recording material surface after fixing was about 30%.

Then, based on this gloss, the fixing speed was set so that the gloss of the image after fixing becomes constant even if the kind (thickness, gloss) of the recording material changes. FIG. 3 shows the matrix. As shown in FIG. 3, for recording materials of the same thickness, the higher the surface gloss, the greater the gloss of the image after fixing. Therefore, the higher the surface gloss of the recording material, the faster the fixing speed. To lower the fixing power and lower the gloss. Further, even if the recording material has the same surface gloss, the thinner the thickness, the higher the image gloss after fixing. Therefore, when the thickness is thin, the fixing speed is increased, and the fixing speed is decreased as the paper thickness increases.

In the fixing device used in this embodiment, the gloss of the image after fixing is almost 3 regardless of the thickness and gloss of the recording material.
Keep it at 0%. Regarding the fixing speed condition, by changing the fixing speed according to the paper type according to the matrix shown in FIG. 3, the gloss of the image after fixing becomes almost equal regardless of the paper type.

Thus, in this embodiment, according to the matrix as shown in FIG. 3 according to the gloss and thickness of the surface of the recording material,
By fixing under the optimum fixing condition according to the gloss (surface property) thickness of the recording material, it was possible to always form an image having almost the same gloss.

Since the optimum fixing temperature and the optimum fixing speed in this embodiment differ depending on the constitution of the fixing device, they are not necessarily limited to these values.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 7. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the present embodiment, the thickness and surface glossiness of the recording material are detected, the fixing temperature is made variable by this, fixing is performed at the optimum fixing temperature, and the gloss of the image after fixing is fixed regardless of the type of recording material. Are equal to each other.

In this embodiment, as shown in FIG.
First, when the copy button is pressed and the recording material is fed, the recording material thickness detecting means 15 detects the thickness of the recording material. Next, the recording material surface glossiness detecting means 16 detects the glossiness of the recording material surface. And CP
In U, the optimum fixing temperature is set by the fixing temperature control means (not shown) based on a matrix of output values detected by these two detecting means as described later.

Also in this embodiment, similar to the first embodiment, Si rubber rollers are used as the fixing roller 51 and the pressure roller 52, the pressure is set to 50 kgf and the nip width is 7.5 mm, and the plain paper (paper A recording material having a thickness of 80 μm and a surface gloss of 5 to 10%) has a fixing speed of 135 mm / sec and a fixing temperature of 180.
It was fixed at ℃. As a result, the gloss of the recording material surface after fixing was about 30%.

Then, based on this gloss, the fixing temperature was set so that the same surface gloss after fixing could be obtained even if the thickness and gloss of the recording material were changed. FIG. 7 shows the matrix. In FIG. 7, in the case of recording materials having the same thickness, the higher the surface gloss, the lower the fixing temperature, and in the case of recording materials having the same surface gloss, the thicker the fixing temperature becomes. Has been raised.

When the copy button is pressed in this state and the recording material is fed, the recording material thickness (basis weight) and surface gloss are first detected, and then the temperature control matrix of FIG. The fixing temperature setting is controlled, and the fixing is performed at the optimum fixing temperature.

As described above, in this embodiment, the fixing can be performed under the optimum fixing condition according to the temperature control matrix as shown in FIG. 7 according to the gloss and thickness of the surface of the recording material. It was possible to form an image with almost the same gloss.

Since the optimum fixing temperature and the optimum fixing speed in this embodiment differ depending on the constitution of the fixing device, they are not necessarily limited to these values.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the thickness of the recording material and the surface glossiness are detected, and thereby the pressure applied between the fixing roller and the pressure roller is made variable, and the nip width is adjusted to perform the fixing under the optimum fixing condition. The gloss of the image after fixing is equalized regardless of the type of recording material.

In this embodiment, as shown in FIG.
First, when the copy button is pressed and the recording material is fed, the recording material thickness detecting means 15 detects the thickness of the recording material. Next, the recording material surface glossiness detecting means 16 detects the glossiness of the recording material surface. And CP
In U, the optimum fixing temperature is set by the pressing force varying means (not shown) based on the matrix of output values detected by these two detecting means as described later.

Also in this embodiment, as in the first embodiment, Si rubber rollers are used as the fixing roller and the pressure roller,
A pressure of 50 kgf and a nip width of 7.5 mm were set, and a recording material of plain paper (paper thickness 80 μm, surface gloss 5 to 10%) was fixed at a fixing speed of 135 mm / sec and a fixing temperature of 180 ° C. As a result, the gloss of the recording material surface after fixing is about 30%.
Became.

Based on this gloss, the pressing force was set so that the same surface gloss after fixing could be obtained even if the thickness and gloss of the recording material were changed. FIG. 9 shows the matrix. In FIG. 9, in the case of recording materials of the same thickness,
The higher the surface gloss, the weaker the pressure (smaller nip width), and for recording materials with the same surface gloss, the thicker the pressure, the wider the nip width.
I am doing it.

As described above, according to the present embodiment, according to the matrix as shown in FIG. 9 according to the gloss and thickness of the surface of the recording material, the optimum condition according to the gloss (surface property) and thickness of the recording material is set. By fixing, it was possible to always form an image having almost the same gloss.

The optimum pressing force in this embodiment is
Since it depends on the structure of the fixing device,
It is not limited to this value.

[0048]

As described above, the first aspect of the present application
According to the invention, before the recording material is conveyed to the fixing device,
The recording material thickness detecting means detects the thickness of the recording material, and the recording material surface gloss detecting means detects the surface gloss of the recording material to set the fixing condition according to the thickness and the gloss of the recording material. Therefore, when fixing is performed, almost the same gloss can be obtained regardless of the thickness and gloss of the recording material.

According to the second invention of the present application,
Since the optimum fixing speed is set according to the thickness and gloss of the recording material, almost the same gloss can be obtained regardless of the thickness and gloss of the recording material.

Further, according to the third invention of the present application, the optimum fixing temperature is set according to the recording material thickness and the surface gloss, so that it is almost the same regardless of the recording material thickness and the gloss. You can get the luster of.

According to the fourth invention of the present application,
Since the optimum pressure is set according to the thickness and gloss of the recording material, it is possible to obtain almost the same gloss regardless of the thickness and gloss of the recording material.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a full-color copying machine according to a first embodiment of the present invention.

FIG. 2 is a flowchart in the first embodiment of the present invention.

FIG. 3 is a fixing condition changing matrix in the first embodiment of the present invention.

FIG. 4 is a diagram showing a recording material thickness detecting means in the first embodiment of the present invention.

FIG. 5 is a diagram showing a recording material surface glossiness detecting means in the first embodiment of the present invention.

FIG. 6 is a flowchart in the second embodiment of the present invention.

FIG. 7 is a fixing condition changing matrix in the second embodiment of the present invention.

FIG. 8 is a flowchart in the third embodiment of the present invention.

FIG. 9 is a fixing condition changing matrix in the third embodiment of the present invention.

FIG. 10 is a schematic sectional view of a conventional full-color copying machine.

FIG. 11 is a schematic sectional view of a conventional full-color copying machine.

FIG. 12 is a schematic sectional view of a conventional fixing device.

[Explanation of symbols]

 5 Fixing Device 15 Recording Material Thickness Detection Means 16 Recording Material Surface Glossiness Detection Means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Rie Saito 3-30-2 Shimomaruko Ota-ku, Tokyo Canon Inc. (72) Inventor Mitsuhiro Ota 3-30-2 Shimomaruko Ota-ku, Tokyo Canon Within the corporation

Claims (4)

[Claims] 1. A roller pair of a fixing roller and a pressure roller which are rotatably arranged while being in pressure contact with each other, and a pressure contact portion formed by the roller pair conveys a recording material having an unfixed image under pressure. In an image forming apparatus equipped with a fixing device for heating and fixing an unfixed image on the recording material, a recording material thickness detecting means for detecting the thickness of the recording material and a recording material for detecting the surface gloss of the recording material. Surface gloss detecting means, and control means set to change the fixing condition of the fixing device according to the output values of the recording material thickness detecting means and the recording material surface gloss detecting means. An image forming apparatus characterized by the above. 2. The image forming apparatus according to claim 1, wherein the fixing condition is a fixing speed. 3. The image forming apparatus according to claim 1, wherein the fixing condition is a fixing temperature. 4. The image forming apparatus according to claim 1, wherein the fixing condition is a pressure applied between the fixing roller and the pressure roller.