JPH03153283A - Image forming device - Google Patents

Abstract

PURPOSE:To automatically change the fixing temperature of a fixing unit to an optimum level and to prevent a trouble which occurs as the result that the changing-over of a switch is forgotten the fixing unit with the aid of a signal from a detection means which automatically detects the sort of a transfer material before an image is formed. CONSTITUTION:In a paper feeding cassette 15, a projection for paper quality 155 which detects a special transfer paper P, that means, a paper whose quality is different from a normal paper is provided on one side of the projection for size 154 thereof. Besides, a detection switch corresponding to the projection 155 is also provided on a device main body 1 side. Therefore, when the quality of the transfer paper P is special, the detection switch of the device main body 1 is pressed by the projection 155 of the cassette 15 and the signal thereof is transmitted 155 of the cassette 15 and the signal thereof is transmitted to the control part of the electric heater of the fixing device 19. Then, the outside surface temperature of the heating roller 190 of the fixing device 19 is controlled to a first set temperature which is a little higher than usual. Thus, the fixing temperature of the fixing device can be automatically changed according to the sort of the transfer material. Besides, the trouble due to the result that the switching of the fixing temperature of the fixing device is forgotten is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an image forming apparatus such as a printer, a copying machine, a printing machine, a facsimile machine, a word processor, and more particularly to an image forming apparatus equipped with a heating type fixing device.

(Prior art) In an image forming apparatus such as a copying machine, a developed image (toner image) on an image carrier is transferred onto a transfer material, and this toner image is heated by a fixing device to form a permanent image on the transfer material. It's here to stay. The fixing device usually consists of a heating roller whose outer surface temperature is heated to a predetermined value, and a pressure roller that applies pressure to the heating roller, and the toner image on the transfer material is formed by this heating and pressure. The image is conveyed while being held between rollers and fixed on the transfer material.

On the other hand, as transfer materials, in addition to so-called plain paper used in normal image forming operations, envelope postcards for direct mail,
Specialty papers, such as label paper and cardboard, whose paper quality is similar to that of ordinary paper, are also increasingly being used.

(Invention or Section M to be solved) However, the fixing temperature of the toner image on the above-mentioned paper and special paper is different, and the fixing temperature on special paper is generally higher than that on sweat paper. Image forming apparatuses that do not allow the temperature setting of the heating roller to be changed have the disadvantage that toner images cannot be properly fixed on special paper.

In addition, even when it is possible to switch the fixing temperature of toner images for permitted paper and special paper, the switching is done with a manual switch, which is cumbersome and
I forgot to turn the switch.

The heating roller was inadvertently heated too much, which caused an increase in costs due to increased power consumption.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus that can automatically change the fixing temperature of a fixing device to the optimum fti for transfer materials of different paper qualities. It is in.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an image forming apparatus equipped with a heating type fixing device that heats a developed image carried on a transfer material to fix it on the transfer material. The apparatus is characterized in that a detecting means for automatically detecting the type of transfer material is provided before one image is formed, and the fixing temperature of the fixing device can be automatically changed based on a signal from the detecting means.

(Function) A normally used transfer material and a special transfer material whose paper quality is different from that of the transfer material have different fixing temperatures for the developed image. Therefore, before image formation, the type of transfer material (i.e., paper quality) is automatically detected by a detection stage, and the fusing temperature of the fusing unit is automatically changed based on the detection signal, and the fusing temperature is adjusted to the optimum fusing temperature. The developed image is fixed on the transfer material.

(Example) Examples of the present invention will be described below with reference to the accompanying drawings, taking a laser beam printer as an example.

First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5.

First, an overview of the image forming apparatus will be explained with reference to FIG.
In the figure, lO is a photosensitive drum which is an image carrier, and surrounding the photosensitive drum lO are a primary charger 11, a developer 12, a transfer charger 13, . A cleaning device 14 is provided, and a paper feed cassette 15 and a paper feed roller 16 are provided on the paper feed side of the photosensitive drum IO.
, registration rollers 17 are arranged, and a conveyance guide 18, a fixing device 19 . Paper ejection roller 20
, a paper discharge tray 21 is provided. Further, a laser scanner 22 for emitting image light and a mirror 23 for exposing the image light onto the photosensitive drum 1O are disposed on the upper side of the apparatus main body 1.

That is, when the photosensitive drum 10 uniformly charged by the negative charger 11 is exposed to image light via the laser scanner 22 and the mirror 23, an electrostatic latent image is formed on the photosensitive drum 10. The electrostatic latent image is directed toward a developing device 12 as the photosensitive tram 10 rotates, and toner is supplied by the developing device 12 to visualize it as a toner image. The toner image is transferred onto the transfer paper P via the transfer charger 13, and the transfer paper P is transferred from the paper feed cassette 15 to the paper feed roller 1.
6, the sheets are taken out one by one and sent to the registration rollers 17, and the registration rollers 17 synchronize the timing and convey them toward the photosensitive drum lO and the transfer charging gl13. The transfer paper P on which the transfer has been completed is sent to the fixing device 19 via the conveyance guide 18, and the toner image is heated and pressurized in the fixing device 19 to be fixed as a permanent image. 20 and stacked on the paper discharge tray 21. still.

After the transfer, the photosensitive drum IO is cleaned of residual toner by a cleaning 3114 and is prepared for the next image formation.

Here, the fixing device 19 is a heating roller 19 that rotates in a fixed direction.
0 and a pressure roller 191, an electric heater is installed inside the heating roller 190, and the outer surface of the heating roller 190 is heated.
The temperature of the outer surface of the heating roller 190 is detected by a temperature detection means such as a thermistor, and the electric heater is controlled by a control means so that the temperature is always constant and suitable for fixing. Further, the pressure roller 191 is pressed against the heating roller 190 via a spring member or the like to form a nip portion for fixing between the pressure roller 191 and the heating roller 190. Therefore, the transfer paper P carrying the toner image is heated by the fixing device 19,
When the toner image on the transfer paper P is conveyed while being pinched by the pressure rollers 190° 191, it is heated and melted and transferred to the transfer paper P.
It will be fixed on top and fixed.

Now, it is fine if the transfer paper P is the so-called plain paper that is normally used in image forming work, but if it is a special paper with a special quality that is often used for envelopes, postcards, labels, etc., it is necessary to achieve good fixing. Generally, it is necessary to slightly raise the fixing temperature of the fixing device 19.

Therefore, a means for detecting image formation on transfer paper P of a special paper quality and increasing the set temperature of heating roller 190 of fixing device 19 will be described below. Note that to change the set temperature of the heating roller 190, it is only necessary to adjust the control means that controls the electric heater, so the explanation thereof will be omitted here. The paper P detection means will be explained.

In this embodiment, the transfer paper P of a special quality on which an image is to be formed is detected by detecting the type of paper feed cassette 15.

The paper feed cabinet 15 is generally box-shaped with its top open, or as shown in Figure fjS2, there are left and right regulating plates 15 on both sites for regulating the movement of the transfer paper P in the width direction.
0 and 150 are provided, and an intermediate plate 151 is provided inside the left and right regulating plates 150 and 150, so that the transfer paper P inside can be lifted to a predetermined height. Further, a hole 153 for lifting the middle plate 151 is formed in the lower part of the end wall 152 of the paper feed cassette 15, which is mounted on the apparatus main body. Paper cassette 1 on the side
A size protrusion 154 is provided to notify the size and orientation of the transfer paper P.

On the other hand, a stopper 30 of the paper feed cassette 15, a stopper 30 of the paper feed cassette 19, and a stopper 30 of the paper feed cassette 15,
The paper feed cassette 15 engages with the size protrusion m154 of the
Detection switch 31 that detects the type of paper feed cassette 15
is inserted into the hole 153 of the end @152 of the shaft 33a.
A lifter 33 and the like that rotate around the center plate 151 and lift the middle plate 151 are attached. Note that the detection switch 31 is the first,
It is composed of three switches: second and third switches 31a, 31b, and 31c.

In the above paper feed cassette 15, the paper feed cassette 15
A paper quality projection 155 is provided on one side of the size projection 154 to detect a special transfer paper P, that is, one whose quality is different from plain paper, and a corresponding detection switch 3 is also provided on the side of the main body of the apparatus
2 will be provided.

Therefore, when the paper feed cassette 15 is installed in the insertion section 1a of the apparatus main body 1 up to the stopper 30 position, the transfer paper P is first
The size is notified to the main body l side by the engagement of the size projection 154 and the detection switch 31. That is, the first, second . Third switch 31a, 31b,
As shown in FIG. 4, the sizes of the eight types of transfer paper P are detected by how the size protrusion 154 presses the paper 31c, and are prepared for subsequent image formation. still.

1 in FIG. 4 indicates that the size protrusion 154 is the first one of the detection switch 31. Second. Third switch 31a.

The case where either 31b or 31c is pressed is shown, and 0 is the case where it is not pressed.

In the above case, if the paper quality of the transfer paper P is special, the paper quality protrusion 155 of the paper feed cassette 15 presses the detection switch 32 of the apparatus main body l, and the signal is sent to the electric heater of the fixing device 19. It is transmitted to the control unit and the fixing device 19
The outer surface temperature of the heating roller 190 is controlled to a first set temperature that is slightly higher than normal. Furthermore, if the paper quality of the transfer paper P is normal, the paper feed cassette 15 is not provided with the paper quality protrusion 155, so the detection switch 32 on the device main body l side will not be pressed, and the fixing @t9 will not be pressed. The heating roller 190 will be controlled to the normal second set temperature.

The flow of the above control is shown in FIG.
If it is detected that the transfer paper P is special paper, the answer is YES and the temperature of the heating roller 190 of the fixing device 19 is raised to the first set temperature (step 100), and if the transfer paper P is detected to be plain paper, the answer is NO. Now it's fuser F! The temperature of the heating roller 190 of 119 is lowered to the second set temperature (step 1
01).

As described above, when only one paper feed cassette 15 is installed in the apparatus main body l, a paper quality protrusion 155 is provided next to the size protrusion 154 of the paper feed cassette 15, and this is attached to the main body l side. By detecting with the detection switch 32,
Next, the paper quality of the transfer paper P on which an image is to be formed can be automatically detected, and the heating temperature setting of the fixing device 19 can be easily changed.

Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 7. Components having the same functions as those in the first embodiment are designated by the same reference numerals, and their explanations will be omitted.

In this embodiment, in addition to the paper feed cassette 15 that stores transfer paper P of normal paper quality, the main body l of the apparatus is provided with a feeder 40 that stores transfer paper P' of special paper quality.

A conveyance path for the transfer paper P is provided between the feeder 40 and the registration roller 17, and a detection means 44 for the transfer paper P° is provided in the conveyance path, and the fuser 19 is heated by a signal from the detection means. The set temperature of the roller 190 can be changed.

In other words, transfer paper P or 4! A feeder 40 having a paper feed roller 40b is provided below the intermediate plate 40a, which is placed on the intermediate plate 40a.
After taking out the transfer paper P° on the top one by one from the lower side via the paper feed roller 40b, this transfer paper P' is transferred to the first conveyance roller 41.a. The paper is sent to the registration rollers 17 via the second transport roller 42. A detection means 44 capable of detecting passage of the transfer paper P° is provided between the first and second conveyance rollers 41 and 42. First and second conveyance rollers 41, 42
A conveyance guide 4 is inserted between them so as to sandwich the transfer paper P from above and below.
As shown in FIG. 7, a hole 45 is provided in the lower plate 43a of this conveyance guide 43, and
The detecting portion 50a of the detecting member 50 of the detecting means 44 having one end formed in an L shape can protrude from the detecting portion 50a near the upper plate 43b of the conveyance guide 43. The other end 50c of the detection member 50 is made movable through the gap between the photointerrupters 51.

Then, when the transfer paper P' is taken out from the feeder 40 by the paper feed roller 40b and the transfer paper P° passes through the conveyance guide 43 via the first conveyance roller 41, the transfer paper P' Since the detecting portion 50a of the detecting member 50 of the detecting means 44 is pushed down by its own weight, the detecting member 50 rotates counterclockwise in FIG. 7 about its shaft portion 50b. Therefore, the other end 50c of the detection member 50 enters the gap between the photointerrupter 51 and blocks the optical signal from the photointerrupter 51.

In this way, an image is about to be formed on the transfer paper P° of a special paper quality via the photo interrupter 51.
The electric heater control unit of the heating roller 190 of the fixing device 19 is notified, and the set temperature of the heating roller 190 is changed.

Note that, as shown in FIG. 6, the detection portion 50a of the detection member 50 is biased upward via the spring member 52, so that the transfer paper P moves inside the conveyance guide 43.

If it passes, the detection member 50 can return to that position.

Note that 40c is a feeder weight for transfer paper P'.

(Effects of the invention) The type of transfer material is automatically detected before image formation, and the fixing temperature of the fixing device can be automatically changed according to the type of transfer material, so that the optimum state is achieved depending on the paper quality. The developed image can be fixed on the transfer material.

In addition, since the type of transfer material and the fixing temperature of the fuser are automatically changed, it is less troublesome than manual methods and avoids the inconvenience caused by forgetting to change the fixing temperature of the fuser. can do.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the image forming apparatus according to the first embodiment, and FIG.
The figure is a plan view of the paper feed cassette of the image forming apparatus, and FIG. 3 is a perspective view of the area around the insertion part of the paper feed cassette of the image forming apparatus.
FIG. 4 is a diagram showing the state of detection of transfer paper size by the image forming apparatus, FIG. 5 is a flowchart for explaining switching of the temperature setting of the fixing device depending on the type of transfer paper in the image forming apparatus, and FIG. 7 is a sectional view of an image forming apparatus according to a second embodiment, and FIG. 7 is a perspective view of a transfer paper detection means of the image forming apparatus.

Claims (3)

[Claims] (1) In an image forming apparatus equipped with a heating type fixing device that fixes the developed image carried on the transfer material by heating, etc., the type of transfer material is automatically detected before image formation. An image forming apparatus characterized in that a detection means is provided, and the fixing temperature of the fixing device can be automatically changed based on a signal from the detection means. (2) The image forming apparatus according to claim 1, wherein the detecting means is constituted by a cassette detection switch corresponding to attachment of a paper feed cassette for transfer material to the main body of the apparatus. (3) The image forming apparatus according to claim 1, wherein the detecting means is constituted by a means for detecting movement of the transfer material passing through a transfer material transport path divided for each type of transfer material.