JP2003005575A - Temperature detector for fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature detector for a fixing device which facilitates the attachment and detachment of a thermistor for the purpose of cleaning and exchanging the same and to simplify the construction around thermistor. SOLUTION: The thermistor 1 for detecting the temperature of a heating roller 40 is constituted by covering a thermistor element with a heat resistant sheet and integrally mounting the thermistor element with a connector 4. The connector 4 of the thermistor 1 is inserted to a connector 50 with a harness 51 previously fixed to the prescribed position of a base 60 of the fixing device, by which the exact positioning, mounting and electrical connecting of the thermistor 1 to the heating roller 40 are performed at a time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detector of a fixing device used in a contact transfer type facsimile machine, a copying machine or the like.

[0002]

2. Description of the Related Art Generally, in a contact transfer type facsimile machine or copier, an electrostatic latent image corresponding to image data of an original is formed on a photosensitive drum, and toner is attracted to the electrostatic latent image on the photosensitive drum. The toner image on the photosensitive drum is transferred to paper, and the fixing device consisting of a pressure roller and a heating roller
The paper on which the toner image is transferred is pressed and heated to fix the toner image on the paper.

In a fixing device comprising a pressure roller and a heating roller, a thermistor is provided to detect the temperature of the heating roller. For example, as shown in FIG. 5, the thermistor 30 is arranged so as to be in contact with a substantially central portion of the heating roller 40 in the axial direction. As shown in FIG. 6 [plan view (a), side view (b)], the thermistor 30 has a thermistor element 31 covered with a heat resistant sheet 32, and is attached to a main body 33. A harness 34 extends from the main body 33,
A relay connector 35 is provided at the terminal of the harness 34. The thermistor 30 is connected to the fixing device by connecting the relay connector 35 and another relay connector (not shown) provided at a terminal of another harness extending from the apparatus main body.

Since the main body 33 has the mounting holes 33a and the positioning dowels 33b, the positioning dowels 33b are fitted into the corresponding recesses of the frame of the fixing device to position the mounting holes 3a.
The thermistor 30 is arranged on the central portion of the heating roller 40 by screwing with the use of 3a.

[0005]

By the way, since the thermistor 30 is arranged in contact with the surface of the heating roller 40, the toner easily adheres to the contact portion. Toner adheres
Once accumulated, the temperature of the heating roller 40 cannot be accurately detected, so the thermistor 30 needs to be regularly cleaned or replaced.

In that case, however, the main body 33 to which the screw is fixed must be removed from the frame of the fixing device, and the relay connector 35 of the harness 34 of the thermistor 30 must be removed from the relay connector of the harness from the main body of the device. Then, after cleaning or replacement, it is necessary to connect the relay connector 35 on the thermistor 30 side to the relay connector on the apparatus main body side so that the main body 33 is accurately positioned on the frame of the fixing device and screwed. In this way, the thermistor 3
Since it is not easy to attach and detach 0, cleaning or replacement of the thermistor 30 is a very troublesome work.

Further, since both the thermistor 30 and the fixing device are equipped with harnesses, it is necessary to arrange wiring of the harnesses and the like, which complicates the structure, which makes it more difficult to attach and detach the thermistor 30. ing.

The present invention has been made in view of such a problem, and the temperature detector of the fixing device which facilitates the attachment / detachment for cleaning or replacement of the thermistor and simplifies the structure around the thermistor. Is intended to provide.

[0009]

In order to achieve the above-mentioned object, the temperature detector of the fixing device of the present invention uses a pressure roller to press the paper on which the toner image is transferred and a heating roller to heat the paper. In a fixing device for fixing a toner image on a sheet, a temperature detecting part having an electric connection terminal for detecting a temperature of a heating roller and outputting a detection signal, and a temperature detecting part fixed to a base of the fixing device are attached. And a holding member having an electrical contact that is connected to the electrical connection terminal of the temperature detection unit.

In this temperature detector, the temperature detector (thermistor) has an electric connection terminal (for example, connector), and the holding member (for example, connector) fixed to the base of the fixing device is connected to the electric connection terminal. Since the temperature detecting portion is attached to the holding member because it has the electric contact, the temperature detecting portion can be accurately positioned, attached and electrically connected to the heating roller at once. That is, the temperature detector can be directly attached to the base of the fixing device.

Therefore, as compared with the conventional structure in which the relay connector is attached to the terminal of the wiring such as the harness, the temperature detecting section can be easily attached and detached, and the temperature detecting section can be easily cleaned and replaced.
In addition, since wiring such as a harness is not required at least in the temperature detecting portion, it is not necessary to arrange the wiring, and the structure around the temperature detecting portion can be simplified.

The temperature detecting unit may be simply attached to the holding member, but in order to more effectively prevent the temperature detecting unit from being pulled by the rotation of the heating roller and falling off the heating roller, the temperature detecting unit may be more effectively prevented. It is preferable that the surrounding structure is a structure that prevents the temperature detecting unit from falling off the heating roller due to the rotation of the heating roller.

Further, since the temperature detecting portion is directly attached to the base of the fixing device, the base is extended in advance to the vicinity of the heating roller and the predetermined position of the base (the temperature detecting portion is in the axial direction of the heating roller). Fix the holding member at a position that comes close to the center).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to embodiments.

FIG. 1 [plan view (a), side view (b)] shows a thermistor as a temperature detector in the temperature detector of the fixing device according to the embodiment. This thermistor 1
A thermistor element (or a thermocouple, a platinum resistance thermometer, or the like) 2 is covered with a heat-resistant sheet 3, and a connector (electrical connection terminal) 4 also serving as a main body is integrally attached. The connector 4 has a mounting hole 4a.

FIG. 2 is a sectional view showing the principal part of the printer section of the image forming apparatus (facsimile machine, copier, or a combination thereof) incorporating the fixing device having the thermistor 1 arranged therein.
3 shows an enlarged sectional view of the fixing device, and FIG. 4 shows a plan view (top view) of the fixing device.

The structure of the printer section of this image forming apparatus will be briefly described. A sheet from a sheet feeding cassette 10 for setting a sheet is transferred to a transfer section and a fixing section (fixing device) along a sheet conveying path P (chain line). Be transported. The sheets in the sheet feeding cassette 10 are taken out one by one by the pickup roller 11, and are conveyed to the transfer unit via the pair of conveying rollers 12 and the pair of conveying rollers 13.

A toner container 20 containing toner, a supply roller 21, and a developing roller 22 are arranged in the developing section of the printer section. The supply roller 21 supplies the toner from the toner container 20 to the developing roller 22 while charging the toner. The developing roller 22 supplies the toner supplied from the supply roller 21 to the photosensitive drum 23.

A photosensitive drum 23 having a photoconductive film on its outer peripheral surface is arranged in the transfer portion, and the photosensitive drum 23 is rotated by a drive source (not shown). The transfer roller 24, which is arranged so as to face the photosensitive drum 23, is arranged so as to be in contact with the outer peripheral surface of the photosensitive drum 23 with the sheet conveyance path P interposed therebetween, and is rotated by a drive source (not shown). A charging brush 25 as a brush roller type charger is arranged around the photosensitive drum 23, and the charging brush 25 uniformly charges the outer peripheral surface of the photosensitive drum 23 while rotating.

The LED print head 26 as an exposure unit arranged around the photosensitive drum 23 has a large number of LEDs arranged in parallel, and the photosensitive drum 2 is based on the input image information.
The outer peripheral surface of 3 is irradiated with light to form an electrostatic latent image corresponding to image information on the outer peripheral surface. Further, a memory removing brush 27 is arranged around the photosensitive drum 23. The memory removing brush 27 is for dispersing the toner image (memory image) remaining on the outer peripheral surface of the photosensitive drum 23 along the contour of the image even after the transfer.

The fixing unit (fixing device) comprises a heating roller 40 having a heater such as a halogen lamp, a pressure roller 41, the thermistor 1 and the like. A heater (for example, a halogen lamp) of the heating roller 40 is heated to a predetermined temperature by a heater driving circuit (not shown). Heating roller 40
The pressure roller 41 fixes the toner image on the paper by pressing and heating the paper after the transfer by the transfer roller 24. The thermistor 1 is arranged in contact with the substantially central portion of the heating roller 40 in the axial direction, detects the temperature of the heating roller 40, the detection signal of the thermistor 1 is taken into the heater drive circuit, and the heater drive circuit detects the detection signal. The heater of the heating roller 40 is controlled based on the above.

The sheet on which the toner image is fixed by the fixing device is conveyed by a pair of conveying rollers 15 and sent to a discharge tray (not shown).

The thermistor 1 is shown in FIG. 3 and FIG.
It is screwed to the base (frame) 60 of the fixing device by a screw (not shown) which is inserted through the mounting hole 4a of the connector 4,
The connector 4 is connected to another connector 50 having a harness 51. Here, the connector 4 is the insertion side (male type) and the connector 50 is the receiving side (female type),
By inserting the connector 4 into the connector 50, the thermistor 1 is accurately positioned at a predetermined position and electrically connected. The connector 50 is fixed in advance to a predetermined position of the base 60 with screws or the like, and the harness 51 of the connector 50 is connected to the heater drive circuit.

In the image forming apparatus constructed as described above, the printing operation is well known, but in general, the photosensitive drum 23 is uniformly charged by the charging brush 25, and the LED print head 26 is applied to the photosensitive drum 23. An electrostatic latent image corresponding to the image information is formed (reversal phenomenon), and the developing roller 22 attracts toner to the electrostatic latent image on the photosensitive drum 23 to form a toner image on the photosensitive drum 23. Then, the transfer roller 24 transfers the toner image on the photosensitive drum 23 onto the sheet. After the transfer, the heating roller 40 and the pressure roller 41 heat and press the paper,
The toner image is fixed on the paper as a permanent image.

In the fixing device of this image forming apparatus, the thermistor 1 can be removed by removing the screw fixing the connector 4 of the thermistor 1 and disconnecting the connector 4 from the connector 50. On the contrary, when mounting the thermistor 1, the connector 4 may be inserted into the connector 50 and the connector 4 may be screwed. Therefore, by simply inserting the connector 4 into the connector 50, the thermistor 1 can be accurately positioned, attached and electrically connected to the heating roller 40 at one time, and the thermistor 1 can be easily attached and detached to clean the thermistor 1. Exchange becomes easy. Since the thermistor 1 does not require wiring such as a harness, there is no wiring, and the structure around the thermistor 1 becomes simpler.

Moreover, since the connector 4 is fixed with screws, even if a tensile force acts on the thermistor 1 by the rotation of the heating roller 40 in the direction of the arrow, the thermistor 1 tends to fall off the heating roller 40. Effectively prevented.

The thermistor 1 is usually arranged at a substantially central portion of the heating roller 40 in the axial direction, but the present invention is not limited to this and may be arranged at an end portion, for example.

In the above embodiment, the thermistor 1
The connector 4 is fixed to the base 60 by screwing the connector 4, but other than the screwing structure, a structure in which a convex portion and a concave portion are fitted, or a structure in which a member such as a hook is hooked may be used. Further, in addition to fixing the thermistor 1 to the base 60, for example, a push button attachment / detachment method may be used so that the connector 4 and the connector 50 do not come off easily from each other.

[0029]

As described above, according to the fixing device of the first aspect of the present invention, if the temperature detecting portion is attached to the holding member, the temperature detecting portion can be accurately positioned with respect to the heating roller, attached, and electrically attached. Since the physical connection can be performed at one time, the temperature detection unit can be easily attached and detached as compared with the conventional configuration in which the relay connector is attached to the terminal of the wiring such as the harness.
Cleaning and replacement of the temperature detector becomes easy. Moreover, at least the temperature detection unit does not require wiring such as a harness,
The wiring around is not required, and the structure around the temperature detecting portion can be simplified.

According to the second aspect of the invention, it is possible to more effectively prevent the temperature detecting portion from falling off the heating roller due to the tensile force generated by the rotation of the heating roller.

[Brief description of drawings]

FIG. 1 is a plan view (a) and a side view (b) of a temperature detector of a fixing device according to an embodiment.

FIG. 2 is a cross-sectional view of a main part of a printer unit of an image forming apparatus including a fixing device provided with the temperature detector.

FIG. 3 is an enlarged cross-sectional view of a fixing device in the image forming apparatus.

FIG. 4 is a plan view (top view) of a fixing device in the image forming apparatus.

FIG. 5 is a schematic view showing an attachment form of a temperature detector of a fixing device according to a conventional example.

FIG. 6 is a plan view (a) and a side view (b) of a temperature detector of a fixing device according to a conventional example.

[Explanation of symbols]

1 Thermistor (temperature detection part) 2 Thermistor element 3 heat resistant sheet 4 connectors (electrical connection terminals) 40 heating roller 41 Pressure roller 50 connector (holding member) 51 harness 60 Base of fixing device

Claims (2)

[Claims] 1. A fixing device for fixing a toner image on a sheet by pressing a sheet on which a toner image is transferred with a pressure roller and heating with a heating roller, for detecting the temperature of the heating roller and outputting a detection signal. And a holding member having an electric contact fixed to the base of the fixing device to which the temperature detecting unit is attached and having an electric contact connected to the electric connecting terminal of the temperature detecting unit. A temperature detector for a fixing device. 2. The temperature of the fixing device according to claim 1, wherein the structure around the temperature detecting portion is a structure for preventing the temperature detecting portion from falling off the heating roller due to rotation of the heating roller. Detector.