JPH03196079A - Image forming device - Google Patents

Abstract

PURPOSE:To properly control the temperature of a fixing device by providing a sheet regulating member for positioning a transfer material nearly in the center part of a paper supply cassette and detecting the size in the width direction of the transfer material in the paper supply cassette through the sheet regulating member in the case of loading the paper supply cassette in a device main body. CONSTITUTION:An operation for inputting the size, etc., in the width direction of the transfer material in a surface temperature setting device is performed through the sheet regulating members 41 and 42 for positioning the width direction of the transfer material in the paper supply cassette 15 where various sizes of transfer material are stacked. Namely, the transfer material is positioned in the center part of the cassette 15 by the members 41 and 42, so that the size in the width direction of the transfer material is shown according to the positions of the members 41 and 42. Therefore, in the case of loading the cassette 15 in the device main body 1, the size of the transfer material is easily detected from the positions of the sheet regulating members 41 and 42. Thus, the temperature of the thermal fixing roller 30 of the fixing device 19 is appropriately controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer that employs an electrophotographic method.

(Prior Art) Generally, in an image forming apparatus using an electrophotographic method, a thermal fixing device is used to fix a toner image transferred onto a transfer material as a permanent image on the transfer material.

As shown in FIG. 9, this fixing device has a heater installed inside.
00a.

It has a pressure roller 101 that is pressed against the heating roller 100 via a spring member or the like, and the heating roller 100 is connected to the heating roller 100 by detecting the outer surface temperature of the heating roller 100 at the shaft end of the heating roller. A temperature sensor 102 that maintains the outer surface temperature at a temperature suitable for fixing is in contact with the temperature sensor 102 .

Here, the temperature sensor 102 detects the heating roller lO.
If the heating roller is positioned in the center of the
Although the temperature of the outer surface of the OO can be detected, there is a problem in that black streaks or the like are generated on the transfer material P due to toner or paper powder adhering to the surface of the temperature sensor 102 when used for a long time. Therefore, the temperature sensor 102 is generally disposed on the shaft end side of the heating roller 100, that is, when the maximum width transfer paper P is passed, the temperature sensor 102 is located in the paper passing area of the transfer paper P but outside the image area. Ru.

The outer surface temperature of the heating roller 100 decreases as the transfer material is fixed. Therefore, in the case of a type in which the transfer material P is conveyed so that the center part of the transfer material P is heated and positioned at the center of the pressure rollers 100 and 101,
In order to maintain the central part of the heating roller 100, where the fixing work is always performed, at a predetermined fixing temperature, a temperature sensor is installed where the fixing work is not performed (that is, the temperature decreases less because the transfer paper P is not constantly passed through). It is necessary to control the temperature of the portion where the toner 102 is disposed to a temperature higher than the fixing temperature.

That is, the heating roller 10 at the end B of the transfer material P in FIG.
In order to control the surface temperature of the heating roller 100 to the fixing temperature T, it is necessary to control the surface temperature of the heating roller 100 at the position A where the temperature sensor 102 is disposed to a temperature equal to the fixing temperature T plus α. Then, depending on the size of the transfer material P, the position of the end B of the transfer material P is detected by the temperature sensor 102.
, it is necessary to adjust the control temperature at the position A where the temperature sensor 102 of the heating roller 100 is placed depending on the size of the transfer material P. It is necessary to change the control temperature depending on the number of sheets of the transfer material P to be fixed.

And the heating roller via the temperature sensor 102 as described above! The outer surface temperature control of 00 is achieved by installing a paper feed cassette containing a fixed size of transfer material P into the main body of the apparatus.
This was done by detecting the size of the transfer material to be used.

(Problem to be Solved by the Invention) However, in the case of a universal type paper feed cassette in which transfer materials P of various sizes can be loaded in one paper feed cassette, it is difficult to install the paper feed cassette in the main body of the apparatus. However, there were disadvantages in that the size of the transfer material P to be used could not be detected and the temperature of the fixing device could not be adequately controlled.

The present invention has been made in view of the above problems, and its purpose is to ensure that the temperature of the fuser is properly controlled even if the paper feed cassette is capable of loading transfer materials of various sizes inside. An object of the present invention is to provide an image forming apparatus that can be used in various ways.

(Means for Solving the Problems) As is clear from the above description, according to the present invention, there is provided a thermal fixing roller in which a heater is disposed in the axial direction and a transfer material for fixing is positioned in the center thereof; A temperature sensor is installed on the shaft end side of the fixing roller to detect the surface temperature of the heat fixing roller and, together with a temperature controller, controls the outer surface temperature of the heat fixing roller. a fixing device having a surface temperature setting device that determines a control setting value of the outer surface temperature of the heat fixing roller at the location where the temperature sensor is disposed by the temperature controller according to the directional size and the number of sheets of the transfer material to be fixed; Further, in an image forming apparatus equipped with a paper feed cassette that can load transfer materials of various sizes in one cassette, the transfer material is movable in the width direction of the transfer material in the paper feed cassette, and A sheet regulating member is provided for regulating movement of the transfer material in the width direction and positioning the transfer material at approximately the center of the paper feed cassette.

The present invention is characterized in that, when the paper feed cassette is mounted on the main body of the apparatus, the size of the transfer material in the paper feed cassette in the width direction is detected via the sheet regulating member.

(Function) The temperature of the heat fixing roller of the fixing device decreases when the transfer material is fixed. Therefore, the surface temperature of the heat fixing roller should be controlled by placing a temperature sensor in the position where the heat fixing roller always performs the fixing operation, but the contact of this temperature sensor may cause black streaks etc. on the transfer material. Therefore, the temperature sensor is generally positioned at the end of the shaft of the heat fixing roller, which is unrelated to the image on the transfer material. Since the thermal fixing roller is heated uniformly in the axial direction by the heater, in order to maintain the temperature of the central part of the thermal fixing roller at a constant fixing temperature, the transfer material on which the temperature sensor is installed must be It is necessary to control the temperature of the area where paper is not constantly passed and where there is little heat radiation to a temperature higher than the fixing temperature. This tendency becomes even more pronounced as the number of sheets of transfer material of the same size that is fixed increases.

Here, since the transfer material is positioned at the center of the heat fixing roller, the size and position of the fixing section of the heat fixing roller are determined by the size of the transfer material in the width direction. Therefore, it is necessary to input the width direction size of the transfer material and the number of sheets to be processed into the surface temperature setting device, and determine the control temperature at the location of the temperature sensor of the heat fixing roller based on the output value.

Therefore, it is necessary to input the size in the width direction of the transfer material into the surface temperature setting device, but in the present invention, this work is performed using a sheet that positions the transfer material in the width direction of the paper feed cassette that can load transfer materials of various sizes. This was done through a regulating member. That is, since the transfer material is positioned at the center of the paper feed cassette by the sheet regulating member, the widthwise size of the transfer material is indicated by the position of the sheet regulating member. Therefore, when the paper feed cassette is installed in the main body of the apparatus, the size of the transfer material can be easily detected from the position of the sheet regulating member.

(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 Figure 1.
In the figure, numeral 10 is a photosensitive drum which is an image carrier, and around the photosensitive drum 10 are a primary charger 11, a developer 12, and so on. 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. 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 body 1.

That is, when the photosensitive drum 10 uniformly charged by the -order 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 the developing device 12 as the photosensitive drum 1O rotates, and toner is supplied by the developing device 12 to form an m-image 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 IO and the transfer charger 13.

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 in the fixing device 19.

After being pressurized and fixed as a permanent image, the paper ejection roller 20
The paper is stacked on the paper discharge tray 21.

After the transfer, the remaining toner on the photosensitive drum 10 is cleaned by a cleaning device 14, and the photosensitive drum 10 is prepared for the next image formation.

Next, the fixing device 19 will be explained with reference to FIGS. 2 and 3.

The fixing device 19 includes a heating and pressure roller 30 that rotates in a fixed direction.
, 31, the toner image supported on the transfer paper P is heated and melted and fixed as a permanent image on the transfer paper P. As shown in FIG. 2, the conveyance of the transfer paper P is of a central reference type, in which the center of the width direction perpendicular to the conveyance direction of the paper P passes through the center of the conveyance device.

The transfer paper P is conveyed while being held between the central portions of heating and pressure rollers 30 and 31.

As shown in FIG. 2, the heating roller 30 is equipped with an electric heater 30a in its axial direction, and its outer surface is heated, and one end of the heating roller 3o is in contact with the heating roller 30. A temperature detector 32 is provided to detect the outer surface temperature. The signal from the temperature sensor 32 is transmitted to the temperature controller 33, and the electric heater 30a is turned on so that the outer surface temperature of the heating roller 30 becomes a constant temperature suitable for fixing.
Controlled by N-OFF, etc. The pressure roller 31 is pressed against the heating roller 30 by a spring member (not shown) or the like, so that the pressure roller 31 can sandwich and convey the transfer paper P together with the heating roller 30.

If the fixing device 19 performs a fixing operation on the transfer paper P, the heat in the heating roller 30 is absorbed by the transfer paper P and the toner image, so that
The outer surface temperature of will drop.

Therefore, if the temperature sensor 32 is positioned at the center of the heating roller 30 through which the transfer paper P always passes regardless of the size of the transfer paper P, the temperature sensor 32 can detect the temperature outside the heating roller 3o. The surface temperature is correctly detected and the temperature controller 33 sets the outer surface temperature of the heating roller 30 to the fixing temperature T. This means that it can be controlled. However, when the temperature sensor 32 is brought into contact with the image area of the transfer paper P of the heating roller 30, toner and paper powder adhere to the temperature sensor 32, causing unnecessary streaks etc. on the transfer paper P. For,
This temperature sensor 32 is disposed on the shaft end side of the heating roller 30, that is, in a position where the maximum width transfer paper P is passed through, but outside the image area.

Since the heating roller 33 is heated uniformly by the electric heater 30a along its axial direction, the central portion of the heating roller 30 where the fixing operation is always performed is kept at the fixing temperature T. In order to maintain the fixing temperature T0, the temperature of the portion where the temperature sensor 32 is disposed generally needs to be controlled to be higher than the fixing temperature T0.

Therefore, a temperature gradient K occurs as shown in FIG. 3 between one end B of the transfer paper P having a constant size S as shown in FIG. 2 and the position A where the temperature sensor 32 is disposed. However, this temperature gradient increases as the number of sheets of transfer paper P of the same size to be fixed increases (1 kn).

Therefore, the temperature at the position A where the temperature sensor 32 is disposed is the fixing temperature T0 at one end B of the transfer paper P plus the additional temperature t.
(n) (t is 5f!a where n is the number of sheets of transfer paper P to be processed). This additional temperature t (n) changes depending on the size S of the transfer paper P, that is, the distance between the positions A and B. That is, as the size of the transfer paper P gradually increases and the distance text becomes shorter, the additional temperature t (n) becomes < , t + (n), t * as shown in Fig. 3.
(n), t becomes smaller as 1(n).

Therefore, the temperature sensor 3 is controlled by the temperature controller 33.
In order to control the outer surface temperature of the heating roller 30 at the position A where the transfer paper P is disposed, the size S in the direction of transfer paper P and the number n of sheets to be fixed are input into the surface temperature setting device 34, and the surface temperature setting device It is necessary to input the set temperature calculated by 34 into the temperature controller 33 and control the outer surface temperature of the heating roller 30 at the location A of the temperature detector 32 based on this set temperature.

To detect the size S in the width direction of the transfer paper P, generally, the paper feed cassette 15 loaded with the transfer paper P of a certain size is connected to the main body of the apparatus.
The type of the 36 paper cassette 15 is detected by attaching it to the paper cassette 15. However, in the present invention, a universal type paper cassette 15 that can load transfer papers P of various sizes is used.
, the size of the transfer paper P in the paper feed cassette 15 in the radial direction is also detected. The paper feed cassette 15 will be explained below with reference to FIGS. 4 to 6.

Section 4 and FIG. 5 show a tray-type paper feed cassette (15), which includes a base 40 on which transfer paper P is stacked, and a transfer paper along grooves 40a, 40a of the base 40. Left and right regulating plates 41.4 move equally in the width direction of P to correctly position the transfer paper P at the center of the base 40.
2, an intermediate plate 43 for lifting the end of the paper feed roller 16 side of the transfer paper P upward so that the transfer paper P can be taken out by the paper feed roller 16; It is composed of left and right mounting parts 44, 44, etc. for correct positioning in the cassette mounting part 1a (see FIG. 1).

As shown in FIG.
0 to form rack parts 41a and 42a,
The rack portion 41a.

42a is meshed with a gear 45 attached to the back surface of the base 40, so the rotation of the gear 45 allows the left and right regulating plates 41, 42 to move an equal distance toward the center or outward on the base 40. It looks like this.

One end of the middle plate 43 near the left and right regulating plates 41 and 42 is pivoted to the base 40 via a support shaft 43a, and the other end on the paper feed roller 16 side is vertically swingable. When the paper feed cassette 15 is attached to the cassette mounting portion 1a of the apparatus main body l, the paper feed roller 16 side is lifted upward. In addition, the mounting portions 44, 44 are configured to be the same as those of other paper feed cassettes that load only transfer paper P of a certain size, in consideration of compatibility with the paper feed cassettes and the like. Incidentally, reference numeral 46 denotes a detachable auxiliary tray for storing the transfer paper P, which is long in the transport direction, in the paper feed cassette 15.

A detection switch 2 is provided on the side of the cassette loading section la of the main body 1 of the apparatus for detecting the size (particularly the size S in the width direction) of the transfer paper P in the paper feed cassette 15. The detection switch 2 is composed of a leaf spring and a transmitter,
Three first .
It is divided into second and third detection switches 2A, 2B, and 2C, and when the first detection switch 2A is pressed, it detects that the width of the transfer paper P is 204 cm or more, and the second detection switch 2B When is pressed, the width of the transfer paper P changes from 164 to 20 mm.
0*1 is detected, and when the third detection switch 2C is pressed, the width of the transfer paper P is detected to be 1601 or less. 9. As shown in FIG. 6, when only the third detection switch 2C is pressed, envelope-sized transfer paper P is detected, and when only the second detection switch 2B is pressed, executive-sized transfer paper P is detected. When only the third detection switch 2A is pressed, legal or A4 size transfer paper P is detected. Also, the second and third detection switches 2
When both B and 2C are pressed, the width of the transfer paper P is 160~
164 mm is detected as B5 size transfer paper P, and when both the first and second detection switches 2A and 2B are pressed, the width of the transfer paper P is detected as 200 to 204 m5,
It is detected as letter-sized transfer paper P.

If the transfer paper P is letter, legal, or A4 size, its width in the width direction is 200 m or more. Since the text is close or 0, the control temperature of the heating roller 30 at the location of the temperature sensor 32 is, for example, To +t3(n)=To (', °t
z(n) Cape o) or To. In addition, if you have B5, executive size transfer paper P, the width direction size is 164 mm to 204 mm, so the temperature sensor 3
The control temperature of the heating roller 30 in the arrangement section 2 is, for example, T o + t * (n). Also, since the width direction size of the envelope-sized transfer paper P is 160 mm or less, the temperature of the temperature sensor 32 is The control temperature of the heating roller 30 in the installation part is, for example, T0+tI(n)
becomes.

On the other hand, on the paper feed cassette 15 side, the detection switches 2A, 2B,
A switch pressing section 47 for pressing 2C is provided.

That is, as shown in FIG. 4, the base 4 of the right regulating plate 42
0 extends toward the device main body 1, and a switch pressing portion 47 is formed at one end thereof.

Accordingly, the right regulation plate 4 is adjusted according to the size S in the width direction of the transfer paper P.
2 is positioned, the switch pressing part 47 is also positioned according to the size of the transfer paper P. Therefore, when the paper feed cassette 15 is installed in the cassette mounting part 1a of the apparatus main body 1, this switch pressing part 47 is positioned. One of the detection switches 2A, 2B, and 2C on the side of the device main body L is pressed. This means that the size S in the radial direction of the transfer paper PQ on which the image is formed and the fixing work is performed can be detected. Therefore, this detection signal is input to the surface temperature setting device 3 of the fixing device 19, and the outer surface temperature of the heating roller 30 is coated, so that the toner image on the transfer paper P is at the proper fixing temperature T. The image is then heated and fixed.

Next, a second embodiment of the present invention will be described with reference to FIG. still,
Components having the same functions as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted.

Like the waste paper cassette 15 of the first embodiment, the paper feed cassette 15 of this embodiment is of a type in which the left and right regulation plates 41 and 42 are automatically opened and closed by gears (not shown). In the cassette 15, one end of the left and right regulating plates 41 and 42 of the transcription cord P is attached to the cassette frame 50 via a support shaft 51 at the front of the apparatus main body, and the other end is vertically swingable. A swing plate 52 is provided, and a cassette frame 5 of the swing plate 52 is provided.
A switch suppressing portion 53 that presses the detection switch 2 on the device main body l side is formed in the other Ig portion extending toward the corner of the device. The swing plate 52 is provided with a diagonal groove 52a that descends toward the center of the paper feed cassette 15, and a protrusion provided at one end of the right regulating plate 42 is formed in the diagonal groove 52a. 54 is inserted.

Therefore, in order to position the transfer paper P in the center of the paper feed cassette 15, when the left and right regulation plates 41 and 42 move to a predetermined position that matches the size of the transfer paper P, the protrusion 5 of the right regulation plate 42
4 moves in the diagonal groove 52a of the rocking plate 52, and the rocking plate 5
2. Move the switch pressing part 53 up and down. On the other hand, the detection switch 2, which consists of a leaf spring and a transmitter on the device main body side, is also on the top.

1st, 2nd, etc. downward. 3rd detection switch → Chi 2A.

Since the paper feed cassette 15 is separated into 2B and 2C,
By attaching the paper feed cassette 15 to the main body L of the apparatus, the switch suppressing section 53 of the paper feed cassette 15 adjusts the width direction size S of the transfer paper P.
The first, second, and third detection switches 2A, 2B,
2C is pressed, and the size of the transfer paper P in the width direction can be detected by attaching the paper feed cassette 15 to the main body l of the apparatus.

Therefore, this embodiment can also achieve the same effects as the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG. still,
Components having the same functions as those in the first embodiment are given the same reference numerals, and their explanations will be omitted.

Left and right regulation plates 41 and 42 of the paper feed cassette 15 in this embodiment
are manually moved, and the left and right regulation plates 41.42
If one of them is moved, the other is moved the same distance in the opposite direction, and the transfer paper P is moved to the paper feed tray 1.
It can be positioned in the center of 5.

The cassette frame 60 on the paper feed roller 16 side at the front of the paper feed force set 15 is provided with a horizontal protrusion 61 having two parallel grooves 61a, 61a, and left and right regulation plates 41.
42, for example, one end of the right regulating plate 42 is bent into a U-shape from below the cassette frame 60 so that the cassette frame 6
It extends toward the protruding part 61 of 0 to form a switch pressing part 62. The upper piece 62a of the switch pressing portion 62 is supported by a protrusion 61 of the cassette frame 60, and is configured to slide on the protrusion 61 as the right regulating plate 42 moves. In addition, the upper piece 62 of the switch pressing part 62
The lower part of a is the parallel groove 61 of the protrusion 61 of the cassette frame 60.
a, 61a and maintains its position. In addition, the parallel grooves 61a, 61a give the operator a click feeling when the switch pressing portion 62 is moved.
Three L-shaped leaf springs 2a-1, 2b-1 whose intermediate portions are pivoted on a support shaft are mounted on the side of the cassette mounting portion la of the main body 1 of the apparatus. ,2
cm1 and the rotation of the plate springs 2a-1, -, the fixing device 19
A detection switch 2 consisting of three transmitters 2a-2, 2b-2, and 2cm2 for transmitting a size signal of the transfer paper P to a surface temperature setting device 34 is provided. Leaf spring 2a-1,=- and transmitter 2a-2
, - and are divided into first, second, and third detection switches 2A, 2B, and 2C.

Therefore, when the transfer paper P is loaded in the paper feed cassette 15 and the left and right regulating plates 41 and 42 are manually moved to position the transfer paper P in the paper feed cassette 15, the widthwise size of the transfer paper P is Switch suppression part 62 of right regulation plate 42 according to S
moves along the protrusion 61 of the cassette frame 60. Therefore, by attaching this paper feed cassette 15 to the main body l of the apparatus, the switch pressing section 62 can be
By pressing any one of the third detection switches 2A, 2B, and 2C, the width direction size S of the transfer paper P in the paper feed cassette 15 is detected, and this embodiment also has the same effect as the first embodiment. Obtainable.

(Effects of the Invention) As is clear from the above description, according to the present invention, even in a paper feed cassette that can load transfer materials of various sizes, the width direction size of the internal transfer material can be indicated by the position of the sheet regulating plate. Therefore, when attaching the paper feed cassette to the main body of the apparatus, the size of the internal transfer material in the width direction was detected via the sheet regulating plate.

Therefore, the temperature of the heat fixing roller of the fixing device can be properly controlled, and it is possible to avoid the inconvenience of not properly fixing the transfer material and causing one defective image.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the image forming apparatus, FIG. 2 is a diagram showing the temperature control means of the fixing device, FIG. 3 is a diagram showing the control temperature with respect to the axial length of the heating roller of the fixing device, and FIG. 4 is a diagram showing the temperature control means of the fixing device. A plan view of the paper feed cassette etc. according to the first embodiment, the fifth
The figure is a perspective view of the same paper feed cassette, FIG. 6 is a diagram showing control temperature of the heating roller etc. with respect to the size of transfer paper, and FIG. 7 is a partial perspective view of the paper feed cassette etc. according to the second embodiment.
FIG. 8 is a partial perspective view of a paper feed cassette etc. according to the tjiIJ3 embodiment, and FIG. 9 is a diagram for explaining the prior art. 1--Device main body, 15--Paper feed cassette, 19--
・Fuser, 30--Heating roller (thermal fixing roller), 3
0a...Electric heater (heater), 32-...Temperature detector, 33...Temperature controller, 34...Surface temperature fixing device, 41.42...Left, right regulation plate (sheet regulation member) , p--transfer paper (transfer material), S--width direction size of the transfer material.

Claims (1)

[Claims] A heater is disposed in the axial direction, and a heat fixing roller is provided in the center of which the fixing transfer material is positioned, and a heater is disposed on the shaft end side of the heat fixing roller to detect the surface temperature of the heat fixing roller. , a temperature sensor that controls the outer surface temperature of the heat fixing roller together with a temperature controller; and a temperature sensor that controls the temperature of the outer surface of the heat fixing roller at the location where the temperature sensor is installed, depending on the size in the width direction of the transfer material perpendicular to the conveyance direction and the number of sheets of the transfer material to be fixed. A fixing device having a surface temperature setting device that determines a control setting value of the outer surface temperature of the roller by the temperature controller, and a paper feed cassette capable of loading transfer materials of various sizes in one cassette. In the image forming apparatus, the transfer material is movable in the width direction within the paper feed cassette, and the transfer material is moved approximately in the center of the paper feed cassette by regulating the movement of the transfer material in the width direction within the paper feed cassette. An image forming apparatus characterized in that a sheet regulating member is provided for positioning the paper feeding cassette, and the width direction size of the transfer material in the paper feeding cassette is detected via the sheet regulating member when the paper feeding cassette is installed in the apparatus main body. .