JP2018018025A - Fixation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix a temperature change of a film by an influence of heat storage of the sliding plate in a fixing device which heats the sliding plate by irradiating the sliding plate with radiation light of a heater and heats the film through the sliding plate. There exists a subject that control of a heater may be overdue.
A temperature detecting member used for controlling a heater is provided on a surface of a sliding plate that comes into contact with a film.
[Selection] Figure 1

Description

  The present invention relates to a fixing device mounted on an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, or a facsimile.

  The following is known as a fixing device used in an electrophotographic image forming apparatus. A cylindrical film, a sliding plate that contacts and slides on the inner surface of the film, a heater that is enclosed in the film and heats the film, and a pressure member that forms a nip portion with the sliding plate via the film And a fixing device.

  In such a fixing device, there is disclosed a device in which a temperature detection member is brought into contact with a sliding plate and a heater is controlled based on a detection temperature of the temperature detection member (Patent Document 1).

Japanese Patent No. 5263131

  However, in the fixing device of Patent Document 1, since the temperature detection member is in contact with the surface of the sliding plate opposite to the surface that slides with the film, the temperature detection responsiveness is such as the heat storage condition of the sliding plate. easily influenced. Therefore, there is a problem that the control of the heater may be delayed with respect to the temperature change of the film.

  One of the preferred embodiments for solving the above problems includes a tubular film, a first surface, and a second surface that is a surface opposite to the first surface, A sliding plate that contacts the inner surface of the film at the first surface and slides on the film, and radiates light toward the second surface of the sliding plate to heat the sliding plate. A heater, a pressure member for forming a nip portion sandwiching the film together with the sliding plate, a temperature detection member for detecting the temperature of the sliding plate, and the temperature detection member according to the detected temperature A temperature control member for controlling the power supplied to the heater, and fixing the image on the recording material by heating the recording material on which the image is formed at the nip portion while heating the recording material. Is provided in contact with the first surface of the sliding plate. That.

  Responsiveness of heater control to the temperature change of the film can be improved.

Schematic side view of the main part of the fixing device in Embodiment 1. 1 is a schematic perspective view of a main part of a fixing device in Embodiment 1. FIG. The fixing nip N vicinity enlarged view of Example 1. Sectional drawing which shows schematic structure of the apparatus in Example 1. Schematic cross-sectional view of the main part of the fixing device in Embodiment 2. The fixing nip N vicinity enlarged view of Example 2. FIG. Schematic cross-sectional view of the main part of the fixing device in Embodiment 3.

[Example 1]
An image forming apparatus according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view illustrating a schematic configuration of a laser beam printer 1 (hereinafter referred to as a printer) as an image forming apparatus including the fixing device 9.

  First, the image forming apparatus 1 irradiates a drum-shaped electrophotographic photosensitive drum (hereinafter also simply referred to as a photosensitive drum) 101 with a laser light image based on image information from the optical system (scanner) 14 in FIG. . Then, a latent image is formed on the photosensitive layer, and the latent image is developed using toner to form a toner image.

  In synchronization with the formation of the toner image, the recording material 2 such as recording paper, an OHP sheet, and cloth is conveyed from the recording material cassette 3 by the pickup roller 4 and the conveying roller pairs 5a and 5b. The toner image formed on the photosensitive drum 101 in the image forming unit formed into a cartridge as the process cartridge 100 is transferred to the recording material 2 by applying a voltage to a transfer roller 15 as a transfer unit provided in the apparatus main body. The recording material 2 onto which the toner image has been transferred is guided by the guide plate 8 and conveyed to the fixing unit 9. The fixing unit 9 applies heat and pressure to the recording material 2 to fix the toner image on the recording material 2. The recording material 2 on which the toner image is fixed is discharged to a discharge tray 13 outside the apparatus via discharge roller pairs 10a, 10b, 11a, 11b, 12a, and 12b.

  The process cartridge 100 includes a photosensitive drum 101 and at least one process means. Here, as the process means, for example, a charging means for charging the electrophotographic photosensitive member, a developing means for developing a latent image formed on the electrophotographic photosensitive member, and a toner for cleaning the toner remaining on the surface of the electrophotographic photosensitive member. There are cleaning means (not shown).

  Next, the configuration of the fixing unit 9 as the fixing device according to the present embodiment will be described with reference to FIGS. In the following description, the conveyance direction of the recording material 2 is defined by X.

  The fixing unit 9 includes a cylindrical film 92, a heater 97 included in the film 92, a sliding plate 93 that slides in contact with the inner surface of the film 92, and a nip that sandwiches the film 92 together with the sliding plate 93. And a pressure roller 91 as a pressure member that forms the portion N. The heater 97 is a halogen heater (hereinafter referred to as a heater) and irradiates the sliding plate 93 with radiant light to heat the sliding plate 93. The recording material 2 onto which the toner image has been transferred is heated by the heat of the sliding plate 93 transmitted through the film 92 while being conveyed at the nip portion N of the fixing unit 9, and the toner image is fixed to the recording material. Is done.

  The film 92 is a cylindrical member having heat resistance and flexibility. The film 92 of this example is composed of a polyimide resin base layer having a thickness of 50 μm, an elastic layer of silicone rubber formed outside the base layer, and a release layer of a PFA resin tube having a thickness of 30 μm formed outside the elastic layer. And having.

  The pressure roller 91 rotates by receiving a driving force from the motor 102 and rotates the film 92 by the rotation. The pressure roller 91 includes a metal core, a silicone rubber layer formed on the outside of the core with a thickness of about 3 mm, and a PFA resin tube formed on the outside of the silicone rubber layer with a thickness of about 40 μm. .

  The sliding plate 93 is a plate-like member having a first surface 93a and a second surface 93b opposite to the first surface 93a. The sliding member 93 comes into contact with the inner surface of the film 92 at the first surface 93 a and is pressed against the pressure roller 91 via the film 92 to form the nip portion N. The sliding plate 93 has a function of transmitting the heat to the recording material through the film 92 when the second surface 93b is heated by receiving the radiation light from the heater 97, and thus has a high thermal conductivity. It is made of a material such as an aluminum plate.

  The second surface 93b of the sliding plate 93 to which the radiation light from the halogen heater 97 is irradiated is provided with a black coating layer in order to easily absorb the radiation light.

  The reflection plate 95 as a reflection member is a member that reflects the radiation light from the heater 97 toward the sliding plate 93. The reflecting member is disposed at a predetermined interval from the heater 97 so as to surround the heater 97 in the hollow portion of the film 92. By collecting the radiation light from the heater 97 on the second surface 93 b of the sliding plate 93 by the reflection plate 95, the radiation light from the heater 97 can be used efficiently, and the film is passed through the sliding plate 93. 92 can be quickly heated. The reflection plate 95 is formed by bending an aluminum plate or the like into a substantially U shape in cross section, for example, having a high reflectance of infrared rays and far infrared rays. In order to increase the heat reflectivity, the reflecting plate 95 may be formed using an aluminum plate having a mirror finish.

  The stay 94 is a member formed by bending a metal plate such as a steel plate so that the cross section is U-shaped, and is provided to improve the bending rigidity of the sliding plate 93. The stay 94 is disposed so as to cover the reflection plate 95 from the outside and the U-shaped opening side faces the nip portion N side, and both U-shaped end portions of the second surface 93b of the sliding plate 93 are respectively provided. Both ends of the recording material in the conveyance direction are provided so as to support the longitudinal direction of the film 92.

  Next, the arrangement and control method of the thermistor 96-1 that is the temperature detection member of the sliding plate 93 and the thermostat 96-2 that is the power interruption member will be described. As shown in FIG. 2, two thermistors 96-1 arranged in the longitudinal direction of the film 92 are held by a stay 94 inside the film 92. As shown in FIG. 1, the thermistor 96-1 is arranged on the downstream side of the recording material transport direction X (the rotation direction of the film 92) outside the reflector plate 95. That is, the thermistor 96 is provided at a position where the radiation light from the heater 97 is not irradiated. The temperature measuring unit 96-1s of the thermistor 96-1 is in contact with the first surface 93a of the sliding plate 93. The region where the thermistor 96-1 is in contact is the surface 93a- of the bent portion bent in the direction away from the inner surface of the film 92 on the downstream side of the rotation direction of the film 92 of the sliding plate 93 in the first surface 93a. 1. The thermistor 96-1 is not in contact with the film 92.

  Control of the heater 97 will be described. The temperature detection result of the thermistor 96-1 is input to the control unit 100 provided in the printer 1 as shown in FIG. 1. The control unit 100 controls the switching element 101 to control the power supplied from the power source 103 to the heater 97 based on the temperature detected by the thermistor 96-1. In the present embodiment, the control unit 100 turns the heater 97 on and off with a triac as the switching element 101 so that the temperature detected by the thermistor 96-1 becomes the target temperature.

  The thermostat 96-2 is a temperature-sensitive member using bimetal, and is disposed so as to sense the temperature of the sliding plate 93-1 in parallel with the longitudinal direction of the thermistor 96-1 and the film 92. The thermostat 96-2 is provided on a circuit that supplies power to the heater 97, and senses an abnormal temperature to cut off the power supply to the heater 97.

  Next, FIG. 3 shows an enlarged view of the vicinity of the fixing nip N, and the temperature detection responsiveness of the thermistor 96-1 will be described. When the recording material 2 is conveyed to the fixing nip N of the fixing unit 9, the heat of the film 92 is transmitted to the recording material 2. Immediately thereafter, the temperature of the film 92 begins to decrease, and the temperature of the sliding plate 93 that contacts the film 92 also begins to decrease. The reason why the responsiveness of the detected temperature to the temperature change of the film 92 is improved by disposing the thermistor 96-1 on the first surface 93a of the sliding plate 93 will be described.

  The distance between the temperature measuring unit 96-1s of the thermistor 96-1 and the fixing nip N is Ns, and the distance between the temperature measuring unit 96-1s and the radiation range H of the heater 97 is Hs. The responsiveness of the detected temperature of the temperature measuring unit 96-1s to the temperature drop of the film 92 caused by the conveyance of the recording material 2 in the fixing nip N is improved as the distance Ns between the temperature measuring unit 96-1s and the fixing nip N is smaller. To do. Further, the responsiveness of the detected temperature of the temperature measuring unit 96-1s is affected by the heat storage of the second surface 93b of the sliding plate 93 as the distance Hs between the temperature measuring unit 96-1s and the irradiation range H is larger. Since it is difficult, improve.

  Contrary to the present embodiment, when the thermistor 96-1 is disposed so as to contact the second surface 93b of the sliding plate 93, the distance Ns between the temperature measuring unit 96-1s and the fixing nip N increases, and the temperature Since the distance Hs between the measurement unit 96-1s and the irradiation range H is reduced, the response of the detected temperature is not good.

  According to the present embodiment, there is an effect that the responsiveness of the heater control to the temperature change of the film is improved.

[Example 2]
A fixing device according to a second embodiment of the present invention will be described with reference to FIGS. Of the configuration of the fixing unit 9 as the fixing device of this embodiment, only the portions different from the first embodiment will be described, and the description of the portions common to the first embodiment will be omitted. In addition, the same code | symbol is attached | subjected and demonstrated to the member common to a 1st Example.

  As shown in FIG. 5, the thermistor 96-3 and the thermostat 96-4 are arranged on the downstream side in the transport direction X outside the reflection plate 95 in the transport direction. The temperature measuring portions 96-3s and 96-4s of the thermistor 96-3 and the thermostat 96-4 are in contact with the first surface 93a of the sliding plate 93. The contact area is a surface portion 93 a-2 that is parallel to the nip surface of the bent portion formed by bending the downstream side of the rotation direction of the film 92 of the sliding plate 93 twice, and is separated from the inner surface of the film 92. .

  FIG. 6 is an enlarged view of the vicinity of the fixing nip N, and the temperature detection responsiveness of the thermistor 96-2 and the thermostat 96-4 will be described. The distance between the temperature measuring units 96-3s, 96-4s of the thermistor 96-3 and the thermostat 96-4 and the fixing nip N is Ns, and the temperature measuring units 96-3s, 96-4s and the heater 97 are irradiated with radiation light. The distance in the range H is Hs. Also in this embodiment, the distance Ns between the temperature measuring units 96-3s, 96-4s and the fixing nip N is small, and the distance Hs between the temperature measuring units 96-3s, 96-4s and the radiation irradiation range H is large. Become. Therefore, according to this embodiment, there is an effect that the responsiveness of the heater control to the temperature change of the film is improved.

[Example 3]
A third embodiment of the present invention will be described with reference to FIG. Of the configuration of the fixing unit 9 of this embodiment, only the portions different from the first embodiment will be described, and the description of the portions common to the first embodiment will be omitted. In addition, the same code | symbol is attached | subjected and demonstrated to the member common to a 1st Example.

  As shown in FIG. 7, the thermistor 96-5 and the thermostat 96-6 are arranged on the outer side of the reflection plate 95 in the recording material conveyance direction and on the downstream side in the recording material conveyance direction X. The temperature measuring unit 96-5s of the thermistor 96-5 is in contact with the bent surface 93a-1 of the first surface 93a of the film 92 of the sliding plate 93, as in the first embodiment. On the other hand, unlike the first embodiment, the temperature measuring portion 96-6s of the thermostat 96-6 is disposed so as to contact the bent portion 93b-1 of the second surface 93b of the sliding plate 93.

  According to the present embodiment, similar to the first and second embodiments, there is an effect that the responsiveness of the heater control to the temperature change of the film is improved. In addition to this, in the present embodiment, it is possible to quickly detect the abnormal temperature of the sliding plate 93 by the thermostat 96-6 when the heater 97 is out of control than in the first and second embodiments. Play.

2 Recording material 9 Fixing portion 91 Pressure roller 92 Film 93 Sliding plate 95 Reflecting plate 96 Temperature detecting member 97 Heater

Claims (4)

A tubular film,
A sliding plate having a first surface and a second surface opposite to the first surface, the first surface being in contact with the inner surface of the film and sliding with the film When,
A heater that radiates light toward the second surface of the sliding plate to heat the sliding plate;
A pressure member for forming a nip portion sandwiching the film together with the sliding plate;
A temperature detecting member for detecting the temperature of the sliding plate;
A control unit that controls electric power supplied to the heater according to a detection temperature of the temperature detection member;
A fixing device for fixing the image to the recording material by heating while conveying the recording material on which the image is formed at the nip portion.
The fixing device according to claim 1, wherein the temperature detecting member is provided so as to contact the first surface of the sliding plate.   The fixing device according to claim 1, wherein the temperature detection member is provided on a downstream side of the first surface of the sliding plate in a rotation direction of the film. The sliding plate has a bent portion that is bent in a direction in which an end portion on the downstream side in the rotation direction of the film is separated from the inner surface of the film,
The fixing device according to claim 1, wherein the temperature detection member is provided on the first surface of the bent portion. A reflection member provided so as to surround the heater, and reflecting the radiation light of the heater to the second surface of the sliding plate;
The fixing device according to claim 1, wherein the temperature detection member is provided at a position where the radiation light reflected by the reflection member is not irradiated.

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