JP2592944B2 - Fixing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing an unfixed toner image on a recording material used in an image forming apparatus such as a copying machine or a printer.

[Background Art] Conventionally, as a means for fixing a toner image on a recording material, a method using a heat roller has been proposed. However, power consumption is increased, and the time required to reach a fixing temperature is increased. However, the present applicant has proposed a fixing method using a heat-resistant sheet which improves the above-mentioned disadvantages in Japanese Patent Application No. 62-14 / 1987.
7884 etc.

[Problems to be Solved by the Invention] However, in order to improve the above drawbacks, an extremely thin sheet (for example, a heat-resistant resin such as polyimide having a thickness of 10 to 50 μm) is required.
), And there was a drawback that handling of the film itself became very difficult, such as wrinkling or breaking.

In addition, even if it is incorporated in an image forming apparatus as a fixing device, if it is damaged during jam processing, there is a problem such as poor fixability of the damaged part in the conventional heat roller fixing, but it is used practically as it is However, in the case of a film, if the film is broken or a hole is formed, the heating element and the toner image on the transfer paper come into direct contact with each other, causing an offset or a jam.
For this reason, the frequency of replacing the film itself increases, and it is necessary to easily perform the film replacement. However, handling difficulty is a serious problem.

Means for Solving the Problems In order to solve the above problems, the present invention provides a heating element, a film that slides on the heating element, and a pressure member that forms a nip with the heating element via the film. A fixing device for nipping and conveying a recording material carrying an unfixed image at the nip and fixing the unfixed image on the recording material by heat from the heating member through the film, wherein at least the heating member And a housing for integrally holding the film and the housing, and the housing is independently detachable from an apparatus main body provided with a pressing member.

FIG. 1 shows a cross section of a fixing device according to an embodiment of the present invention.

Reference numeral 1 denotes a low-heat-capacity linear heating element having a thickness of 1 m as an example.
m, width 10mm, length 240mm alumina substrate 1a width
The energization applied from the both ends in the longitudinal direction with a coating of 1 mm is given, for example, as a pulse-like waveform of DC 100 V with a period of 20 mmsec, and the temperature or the frequency is controlled by a temperature detecting element (not shown) so that the temperature becomes constant.

Reference numeral 2 denotes a fixing film, which is made of a heat-resistant resin such as polyimide, polyether isid, or PES and has a thickness of about 20 μm, and a release layer such as PTEF is coated on one surface of the film. In general, the total thickness of the film is preferably 100 μm, more preferably 50 μm or less.

The fixing film is stretched between a driving roller 3 and a tension roller 4 and forms a film transport path together with the heating element 1. The fixing film 2 is tensioned by urging the tension roller 4 in the direction of arrow A by urging means (not shown).
Conveyed in the direction.

The drive roller 3 is provided on the surface to ensure the conveyance of the film.
A coating such as Si rubber is applied.

Reference numeral 5 denotes a pressure roller which has a rubber elastic layer of silicon rubber or the like with good releasability, and is pressed against the film heating body with a total pressure of 4 to 7 kg. Further, both ends of the pressure roller 5 are supported by bearings (not shown) so that the pressure roller 5 is driven to rotate by the fixing film 2.

The heating element 1 is fixed on a stay 6 having a rigidity to withstand the pressing force.

The transfer paper is fed between the fixing film 2 and the pressure roller 5, and the toner image on the transfer paper is heated and melted by heat and pressure by the heating element 1 and the pressure roller 5 and fixed on the transfer paper. It is discharged outside the device.

In this embodiment, the heating element 1, the fixing film 2, the driving roller 3, and the tension roller 4 are integrally housed in a housing 7, and are independently and detachably attached to a fixing device main body 8, thereby forming a film cartridge.

 FIG. 2 shows a perspective view of a film cartridge portion.

The film cartridge further includes entrance guide members 9 and 9 'for guiding the transfer paper to a nip formed by the heating element 1 and the pressure roller 5, and the transfer paper after passing the nip is not separated from the film. There is provided a separating member 10 for preventing the wrapping.

A sheet made of polyimide or the like is used as the separating member.
And an example in which it is bonded to the housing 7 with a gap from the gap. This can increase the relative position accuracy with the fixing film, and as a result, can interpose GaP with the film, so that the transfer paper can be guided and separated to the nip and other entrance guides 9, 9 'and separation Since the member 10 is easily stained by toner or the like and causes wrinkles or jams, the above trouble can be prevented by replacing the film at the same time.

Since the fixing film 2 is an extremely thin film as described above, it is not possible to control the deviation of the belt by a crown roller or a flange, and it is necessary to detect the position of the film and return the film to its original position. As a film position detecting means, a photo-interrupter of a reflection type, a transmission type or the like, a micro SW, or the like is used. By providing a window in a part of the housing 7, the film end surface can be detected. Window 11
By providing a transparent member, it is possible to prevent the heat of the heating element 1 of the photointerrupter, which is relatively weak to heat, from being directly applied, thereby improving reliability and life.

The housing 7 is made of a material having a high heat insulating effect, such as a heat-resistant resin, so that the heat can be reduced and the energy can be effectively used. In the event of a burn, it can be prevented. In that sense, it is more preferable to perform electrostatic flocking on the outer periphery.

In addition, when preparing a complex type of film or heating element at the position where the fixing property or the surface property after fixing is changed, the combination of the film and heating element can be freely changed because the film and heating element can be exchanged as one, and the serviceability and user flexibility It is also possible to measure improvement.

In the above-described embodiment, an endless film is used as the fixing film, but an endless film may be used.

Further, the heating element, the driving roller, the tension roller, and the like may be appropriately exchanged with respect to the film cartridge and may be reused.

The transfer cartridge transport guide and the separation unit are integrated into the film cartridge, but these can be left in the fixing device body.In addition, a part of the discharge unit such as the discharge roller can be provided on the film cartridge. It is.

[Effects of the Invention] As described above, since at least the fixing film and the heating element are detachably attached to the fixing device main body, the exchangeability of the fixing film is improved, and the film is damaged at the time of jam processing or the like. In addition, by providing a transfer paper guide and a separation guide integrally, the reliability of transfer paper transfer can be improved.

Furthermore, since the film and the heat generating element can be exchanged as a unit, it is possible to cope with a heater or the like adapted to the film characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fixing device according to an embodiment of the present invention, and FIG. 2 is a perspective view of the fixing device of the embodiment shown in FIG. 1 is a heating element, 2 is a fixing film, 3 is a driving roller, 4 is a tension roller, 5 is a pressure roller, 7 is a housing of a film cartridge, 9 and 9 'are entrance guides, 10 is a separating member, 1
Reference numeral 1 denotes a film position detection window.

Claims (1)

(57) [Claims] 1. A heating element, a film sliding on the heating element, and a pressing member forming a nip with the heating element via the film, and an unfixed image is carried on the nip. In a fixing device for nipping and conveying a recording material and fixing an unfixed image on the recording material by heat from the heating body via the film, the fixing device has a housing that holds at least the heating body and the film integrally. The fixing device is characterized in that the housing is independently detachable from an apparatus main body provided with a pressure member.