JPH0627962B2 - Microwave fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of the invention [Industrial field of application] The present invention relates to the surface of an unfixed image carrier which is output from an image forming unit in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus. Of the present invention relates to a device for fixing the image.

More specifically, the present invention relates to a fixing device of a type in which a microwave is applied to perform a fixing process.

[Conventional technology]

Microwave fixing has advantages such as shorter preheating time than heat fixing using a heater. Conventionally, this type of device forms a microwave path from a microwave source such as a magnetron through a waveguide to an absorption end, and a fixing unit is provided in the middle of the path, and an unfixed image carrier (toner adhesion) is attached to the fixing unit. The recording paper, referred to as a recording paper hereinafter), was introduced to fix the image.

[Problems to be solved by the invention]

However, the conventional device as described above needs to be provided with a cooling device for the microwave absorption end because it has a high temperature due to microwave absorption, and in some cases, most of the microwave energy P is consumed at the absorption end. However, there is a drawback that only a small part of the energy W is used for fixing (that is, P> W).

The present invention eliminates the above-mentioned drawbacks of the conventional apparatus, and provides a microwave fixing device which does not require a cooling device and is efficient.

(B) Structure of the Invention [Means for Solving the Problems] The present invention provides a closed loop microwave waveguide in which a microwave source is connected to a closed loop microwave waveguide including a fixing device in the middle through another waveguide. A gist of a microwave fixing device is characterized in that a one-way microwave traveling wave is generated, and the object to be fixed introduced into a fixing device is fixed by the microwave traveling wave.

[Work]

With the above configuration, by adjusting the output of the microwave source and the phase shifter to achieve matching, the microwave traveling wave is constantly present in the closed loop waveguide, and the microwave energy is used for fixing at a high rate. Be seen. On the other hand, the number of microwaves reaching the absorption edge is reduced or substantially eliminated, and energy loss and heat generation due to the absorption edge are reduced or reduced, so that it is not actually necessary to install a cooling device.

〔Example〕

FIG. 1 shows an embodiment of the present invention, 1 is a magnetron, 2.3
4 is a waveguide, 5 is a branch element, 6 is a phase shifter (phase shifter), and 7 is a fixing device. The fixing device 7 is, for example, JP-A-52
As disclosed in Japanese Laid-Open Patent Publication No. 2003-0039, a slit is provided in the waveguide wall, and the microwave leaking from the slit melts and fixes the toner on the surface of the recording paper P introduced into the fixing device. The branch element 5 is called a magic tee, and has four branches 51 to 54 as shown in FIG.
The branch 51 faces the waveguide 2 connected to the magnetron, and the branches 52 and 53 respectively form the closed loop waveguide 3.
Facing 4 The other branch 54 is connected to an absorption end (not shown) through a waveguide (not shown).

As is well known in the three-dimensional circuit theory, the magic tee 5 emits only from the H branch 52 when microwaves of the same amplitude and the same phase enter from the symmetrical branches 51 and 53, and the emission from the E branch 54 and the branches 51 and 53. No reflections from.

Microwaves generated from the magnetron 1 are guided to the waveguide 3 by the magic tee 5 via the waveguide 2. The microwave traveling in the waveguide 3 loses a part of energy in the fixing device 7, and then enters the magic tee 5 again via the waveguide 4. At this time, if the microwaves of the waveguides 2 and 4 satisfy the above matching condition, all the energy incident from the waveguide 4 is guided to the waveguide 3 again. Therefore, by adjusting the magnetron output and the phase shifter 6 to achieve matching, a traveling wave will steadily exist in the closed loop waveguides 52, 3, 4, and 53. At this time, if the loss of the waveguide wall other than the fuser portion and the reflection by the fuser are ignored, the magnetron output P and the energy W consumed for the fuser
Are equal (P = W). So, ideally, 100% of the microwave energy would be used for fixing. If there is a match, there is no microwave exiting the branch 54 to the absorption edge not shown in FIG. 1, so there is no energy loss due to this absorption edge.

Although the reflection by the fixing device is not taken into consideration in the above-mentioned embodiment, the reflection to some extent is inevitable in practice. Due to the reflection, a traveling wave in the reverse direction is generated in the waveguide 2 and further in the waveguide 3, and interference with a wave in the forward direction occurs, which causes uneven fixing. To prevent this, it is advisable to insert a unidirectional device (isolator) 8 in the middle of the waveguide 2 as shown by the dashed line in FIG. In this case, the efficiency deteriorates by the amount of energy loss due to the isolator 8.

C. Effect of the Invention As described above, an efficient microwave fixing device can be constructed by adopting a structure in which a unidirectional traveling wave is generated in the closed loop waveguide and a fixing device is placed on the way. . Also, since there is no absorption edge that consumes a large amount of energy, it is not necessary to attach a cooling device.

[Brief description of drawings]

FIG. 1 is a structural view of an embodiment of the device of the present invention, and FIG. 2 is a perspective view of a magic tee. Reference numeral 1 is a magnetron, 2/3 and 4 is a waveguide, 5 is a branch element, 6 is a phase shifter, 7 is a fixing device, 8 is a unidirectional device, and P is a recording paper to be fixed.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-58-88085 (JP, A) JP-A-58-217971 (JP, A) JP-A-57-84472 (JP, A) JP-A-52- 20039 (JP, A) JP 59-87790 (JP, A) JP 58-201292 (JP, A) JP 58-136071 (JP, A) Actual development Sho 59-136189 (JP, U) Actual Open Sho 54-34458 (JP, U) Actual Open Sho 58-45552 (JP, U)

Claims (1)

[Claims] 1. A closed loop waveguide having a microwave source, a fixing portion connected to the microwave source along a direction intersecting a moving direction of a recording material, and an isolator provided in the closed loop waveguide. A microwave fixing device characterized by performing a one-way microwave traveling wave in a closed loop waveguide for fixing.