JP2968345B2 - Electrophotographic device fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic system (a system in which an image formed on a photoreceptor is transferred to paper and recorded) using a laser, such as a printer, a copying machine, and a facsimile.
Thus, the present invention can be applied to an electrophotographic apparatus that performs recording on paper. Specifically, in such an electrophotographic apparatus, an image on the sheet is fixed between the fixing roller and the pressure roller by passing the image-transferred sheet, and the thermistor is pressed against the fixing roller to reduce the surface temperature of the fixing roller. It relates to a fixing device to be detected.

[0002]

2. Description of the Related Art In a conventional fixing device, for example, as shown in FIG. 5, a pressure roller 1 is pressed against a fixing roller 2 and a thermistor 4 of a thermistor unit 3 is pressed against the fixing roller 2. There is something. The thermistor unit 3 includes a thermistor 4 provided on a rigid holding member 5 and is supported by an elastic bracket 7 screwed to a cover 6.

[0003] Then, the paper 8 conveyed after the image is transferred.
Is passed between the pressure roller 1 and the fixing roller 2 to fix the image on the paper 8 by heat and pressure, while the thermistor 4 detects the surface temperature of the fixing roller 2.

[0004]

However, in this conventional fixing device, since the thermistor unit 3 is supported by the bracket 7 screwed to the cover 6 in the cover 6, the cost is reduced as much as the bracket 7 is required. However, since it is difficult to remove the thermistor unit 3 from the cover 6, replacement of the thermistor unit 3 is troublesome.

Accordingly, an object of the present invention is to reduce the cost and facilitate replacement of the thermistor.

[0006]

A solution for the] Therefore, the invention according to claim 1, in the fixing device of an electrophotographic apparatus for detecting the surface temperature by pressing a thermistor thermistor units on the surface of the fixing roller, the thermistor unit To
Connector and a plate-like elastic holding one end with the connector
Member, the thermistor provided in the elastic member,
While composed of a lead wire extending from the connector, a mounting hole provided on the cover covering the fixing roller, and insert the thermistor unit from the outside of the cover to the mounting hole, the thermistor
When installing the monitor unit, put the lead wires out of the cover
Position and support the thermistor unit with its cover
Along with connecting the lead wire to a temperature control unit ,
It is characterized by the following. According to a second aspect of the present invention, in a fixing device of an electrophotographic apparatus for detecting a surface temperature by pressing a thermistor of a thermistor unit against a surface of a fixing roller, the thermistor unit includes a connector and a connector.
Plate-shaped elastic member whose one end is held by a
The thermistor provided for
While composed of a lead wire, a mounting hole provided on the cover covering the fixing roller, and insert the thermistor unit from the outside of the cover to the mounting hole, when mounting the thermistor unit
Is located outside the cover and the cover
The thermistor unit is supported by a support member provided outside.
And connecting the lead wire to the temperature control unit.
That, characterized in that.

[0007] The invention described in claim 3 is claim 1 or
2. Thermistor in the fixing device of the electrophotographic apparatus described in 2.
The elastic holding member is provided on the surface of a plate-like elastic holding member.
The material is placed on the thermistor unit while holding the base end.
-Elastic holding member when inserting the mister unit into the mounting hole
So that the tip of the
The cover is provided with a mounting hole. Claim
The invention according to claim 4 provides the electronic device according to claim 1 or 2.
In the fixing device in the photographic device, the step in the thermistor unit
And insert the thermistor unit into the mounting hole
When the abutting of the step, the insertion amount of the thermistor unit
Is regulated.

[0008]

According to the first aspect of the present invention, there is provided a fixing device.
Or remove the fixing roller when removing the thermistor unit.
Remove the thermistor unit from the outside of the covering cover.
When installing, insert thermistor from the outside of the cover into the mounting hole.
Thermistor unit.
The fixing thermistor against the surface of the fixing roller.
The support is again supported by the cover. In the invention according to claim 2,
When removing the fuser or thermistor unit,
The support member provided outside the cover that covers the fixing roller
-Remove the mister unit. When attaching
Insert the thermistor unit into the mounting hole from outside the
Apply the thermistor of the thermistor unit to the surface of the fixing roller.
, And support the thermistor unit again with the support member.
Carry.

According to the third aspect of the present invention, the thermistor
When installing a knit, insert it into the mounting hole to
The tip of the holding member contacts the fixing roller, and the surface of the fixing roller
Deflection of the elastic holding member by tilting to fix the thermistor
And press it against the surface of LA. According to the fourth aspect of the present invention,
-When mounting the
The insertion amount of the thermistor unit is regulated.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a schematic view of the overall configuration of an internal mechanism of a laser printer having a fixing device according to an embodiment of the present invention. What is indicated by reference numeral 10 in the drawing is the apparatus main body. In the apparatus main body 10, a belt-shaped photoconductor 11 is provided substantially at the center. Around the photoconductor 11,
In the driving direction shown by the arrow in the figure, the charger 12 and the developing device 1 are sequentially arranged.
3. The transfer device 14 and the cleaning device 15 are arranged. Then, an optical writing unit 16 is arranged below the charging unit 12 and the cleaning unit 15. In addition, the optical writer 16
A sheet cassette 18 in which sheets 17 are set is detachably attached to the lower side. On the upper side of the apparatus main body 10, a first discharge stack unit 20 is provided. On the left side of the figure, a second paper discharge stack unit 21 dedicated to paper with strong stiffness such as thick paper or an envelope or very weak paper such as OHP sheet is provided. Then, a paper discharge tray 22 is detachably attached to the second paper discharge stack 21.

Thus, the paper feed roller 23 is driven to feed out the set paper 17 in the paper feed cassette 18 in the direction of arrow A. Then, the sheet 17 is conveyed to the upper side of the photoconductor 11 by the registration roller 24 at a certain timing.
The photoconductor 11 is driven in a counterclockwise direction as indicated by an arrow. At this time, the surface is uniformly charged by the charger 12, and the photoconductor 11 is irradiated with the laser beam L from the optical writer 16 to rest on the photoconductor 11. An electrostatic latent image is formed. This latent image is visualized by the toner when passing through the developing device 13. And this visible image is
The image is transferred by the transfer unit 14 to the lower surface of the sheet 17 conveyed above the photoconductor 11. The transferred paper 17 is conveyed between a fixing roller 26 and a pressure roller 27 of a fixing device 25 to fix a visible image. On the other hand, the photosensitive member 1 after the transfer of the visible image
1 is cleaned by the cleaning device 15.

On the other hand, the recorded paper 17 exiting the fixing device 25
Is conveyed by a paper discharge roller 29 of a paper discharge device 28, further guided upward by a paper conveyance guide 30 to be inverted, and discharged by a paper discharge roller 31 in the direction of arrow B to be first
Is stacked on the discharge stacking section 20 of the printer. Also, paper 1
When the reference numeral 7 is a thick paper or an OHP sheet, the switching guide 32
The paper discharge direction is switched by the discharge roller 29 and the arrow C
In the direction, and is stacked on the second discharge stack unit 21.

The above-mentioned fixing device 25 has a structure as shown in FIG. 1 in detail, and has a lower fixing cover (cover) 4 which covers the lower side of the fixing roller 26 at the top and bottom in the figure.
0 and a fixing upper cover 41 that covers the upper side of the pressure roller 27. The fixing roller 26 has a built-in heater 42 and is pressed against the pressure roller 27 by an appropriate urging means. A lower entrance guide plate 43 is attached to the lower fixing cover 40, and an upper entrance guide plate 44 is attached to the upper fixing cover 41.

The fixing lower cover 40 has a mounting hole 40a on the right side in the figure. The connector 46 of the thermistor unit 45 is detachably attached to the attachment hole 40a. As shown in FIG. 2, the thermistor unit 45 has the connector 46 and a proximal end formed by the connector 46.
There a plate-shaped elastic holding member 47 to be held, a thermistor 48. provided on the surface of the elastic holding member 47. Figure
As shown, the connector 46 includes an elastic holding member 47.
A step is provided below the holding part. Then, as shown in FIG. 1, the thermistor unit 45 is inserted into the mounting hole 40a.
When inserting the cover, the stepped portion is brought into contact with the lower fixing cover 40 to
ー Regulates the insertion amount of the mister unit 45 and positions it
At the same time, the thermistor 48 is pressed against the fixing roller 26. Then, the thermistor 48 is connected to a temperature controller (not shown) via a lead wire 49 extending from the connector 46.
Electrically connected to

Then, as shown in FIG.
6 and the pressure roller 27 are rotated.
In the meantime, heat and pressure are applied to the sheet 17 which is conveyed after the image is transferred and the image on the sheet 17 is fixed. At the same time, the surface temperature of the fixing roller 26 is detected by the thermistor 48. Thus, the surface temperature of the fixing roller 26 is always kept constant by controlling the temperature controller in response to the detection signal.

During the image fixing operation, the thermistor 48 is worn due to, for example, friction with the fixing roller 26. When the thermistor 48 is to be replaced, the connector 46 is connected to the mounting hole 40a from outside the lower fixing cover 40. Then, the pressing of the thermistor 48 against the fixing roller 26 is released. Then, replace it with a new thermistor unit 45,
As shown in FIG. 1 again, the thermistor 48 is
6, the connector 46 is attached to the attachment hole 40a by elastically pressing the surface.

In the illustrated embodiment described above, the thermistor 48 is detachably supported by the cover, that is, the lower fixing cover 40. However, the thermistor 48 is detachably supported by a support member outside the cover. Can also.

In this case, as shown in FIG. 3, for example, a window 40b is opened on the lower right side of the lower fixing cover 40 in the figure. On the other hand, the connector 46 of the thermistor unit 45 is detachably attached to the upper end of the support member 50 fixedly provided outside the lower fixing cover 40. Then, the distal end side of the thermistor 48 is elastically pressed against the surface of the fixing roller 26 through the window 40b, and the entire thermistor unit 45 is supported by the support member 50.

When replacing the thermistor unit 45, the connector 46 is removed from the support member 50 and the pressing of the thermistor 48 against the fixing roller 26 is released. Then, the thermistor unit 45 is replaced with a new thermistor unit 45, and the thermistor 48 is moved to the window 40 as shown in FIG.
b, the connector 46 is elastically pressed against the surface of the fixing roller 26 to attach the connector 46 to the support member 50.

[0020]

Therefore, according to the present invention, the mounting hole is provided.
Through the thermistor from outside the cover that covers the fuser roller.
Fixing unit can be attached and detached.
For easy installation and removal of the heater and thermistor unit
can do. According to the first aspect of the present invention,
In addition, it eliminates the need for separate parts such as
Stall down can be achieved. The invention according to claim 3
According to the thermistor unit, elastic
The tip of the holding member is oriented off the center of the fixing roller
Was bent and damaged by hitting the fixing roller
Of the thermistor against the fixing roller
It is possible to eliminate the risk of becoming distorted. Claim 4
According to the described invention, the thermistor unit is attached
When inserting the thermistor unit,
Is regulated, the misalignment of the thermistor unit
The pressing force of the thermistor against the fixing roller varies
The risk of inaccurate temperature detection
You.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a fixing device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a thermistor unit provided in the fixing device.

FIG. 3 is a sectional view showing a fixing device according to an embodiment of the present invention described in claim 2;

FIG. 4 is an overall schematic configuration diagram showing an internal mechanism of a laser printer including the fixing device of the present invention.

FIG. 5 is a sectional view showing a conventional fixing device.

[Explanation of symbols]

 25 Fixing Device 26 Fixing Roller 40 Lower Fixing Bar (Cover) 40a Mounting Hole 40b Window 45 Thermistor Unit 46 Connector 47 Elastic Holding Member 48 Thermistor 50 Supporting Member Outside Cover

Claims (4)

(57) [Claims] 1. A fixing device for an electrophotographic apparatus, wherein a thermistor of a thermistor unit is pressed against a surface of a fixing roller to detect a surface temperature of the fixing roller.
Into a connector and a plate-like
An elastic member, the thermistor provided on the elastic member,
A cover for covering the fixing roller is provided with a mounting hole, and the thermistor unit is inserted from the outside of the cover into the mounting hole, and the lead wire is attached when the thermistor unit is mounted.
Is located outside the cover, and the thermistor is
While supporting the knit, the lead wire is connected to the temperature controller.
Connected to an electrophotographic device, a fixing device. 2. A fixing device for an electrophotographic apparatus, wherein a thermistor of a thermistor unit is pressed against a surface of a fixing roller to detect a surface temperature of the fixing roller.
Into a connector and a plate-like
An elastic member, the thermistor provided on the elastic member,
A cover for covering the fixing roller is provided with a mounting hole, and the thermistor unit is inserted from the outside of the cover into the mounting hole, and the lead wire is attached when the thermistor unit is mounted.
Is provided outside the cover and provided outside the cover.
The thermistor unit is supported by holding members and
A fixing device for an electrophotographic apparatus, wherein the lead wire is connected to a temperature controller . 3. The thermistor is provided on a surface of a plate-shaped elastic holding member, and the elastic holding member is provided on the thermistor unit while holding a base end thereof, and the elastic holding is performed when the thermistor unit is inserted into the mounting hole. The fixing device according to claim 1, wherein the mounting hole is provided in the cover such that a front end of the member is away from the center of the fixing roller. 4. The method according to claim 1, wherein a step is provided in the thermistor unit, and when the thermistor unit is inserted into the mounting hole, the step is abutted to regulate the insertion amount of the thermistor unit. Or a fixing device for the electrophotographic apparatus according to 2.