Uv Impeded Toner

Abstract

The invention relates to a method and a heating device for heating at least one printing agent on a printing material (4), which is passed along a transport path through said heating device, comprising at least one microwave applicator (2) and at least one microwave absorber element in the outer perimeter of said microwave applicator.

Description

They show in

FIG. 1 a heating device with absorber elements configured as gas-discharge lamps;

FIG. 2 a heating device with absorber elements configured as sliding gas-discharge lamps;

FIG. 3 a heating device with sliding panels of a microwave applicator;

FIG. 4 a heating device with sliding filter elements;

FIG. 5 a heating device with a coupling element; and,

FIG. 6 a heating device with diaphragms that partially enclose gas-discharge lamps.

FIG. 1 is a schematic illustration of a side elevation of a heating device which, as depicted, is configured as a fusing device 1. In this case, a not-illustrated non-fused toner image is applied to printing material 4. Printing material 4, including the non-fused toner image, is transported along a transport direction 5 on its transport path through fusing device 1, as indicated by an arrow. To achieve this, not-illustrated. advance and guiding elements are provided.

Through slits 6 and 7, printing material 4 is passed through fusing device 1. Fusing device 1 comprises a microwave applicator 2, in which not-illustrated microwave radiation is applied to printing material 4. To achieve this, printing material 4 passes through microwave application zone 3 of microwave applicator 2. To do so, slits 6, 7 are provided in panels 11, 12 of microwave applicator 2. Through slits 6, 7, microwave radiation may exit microwave application zone 3. This is the so-called leakage radiation which is no longer available to the application process, i.e., the fusing process, inside microwave applicator 2.

Irradiation devices configured as gas-discharge lamps 8, 9 are provided outside microwave applicator 2. In so doing, viewed in transport direction 5 of printing material 4, a gas-discharge lamp 8 is located upstream of microwave applicator 2 and, viewed in transport direction 5 of said printing material, a second gas-discharge lamp 9 is located downstream of microwave applicator 2. In this case, gas-discharge lamps 8, 9 represent absorber elements which absorb microwave radiation exiting, for example, through slits 6, 7 from microwave application zone 3 of microwave applicator 2. Gas-discharge lamps 8, 9 are filled with gas which is excited by the absorbed microwave radiation to emit electromagnetic radiation. In the case illustrated here, gas-discharge lamp 8 is energized to emit electromagnetic radiation predominantly in the infrared region of the spectrum. Gas-discharge lamp 9 is energized by microwave radiation which substantially exits through slit 7 of microwave application zone 3 in order to emit radiation predominantly in the ultraviolet region. A selection of the spectral emission region of gas-discharge lamps 8, 9 is achieved, in so doing, via the selection of the gas with which gas-discharge lamps 8, 9 are filled.

As mentioned, toner particles lie unfixed on printing material 4. Printing material 4 may be a sheet of paper, for example. Viewed in transport direction 5 of printing material 4, said printing material is first passed under gas-discharge lamp 8. Infrared radiation preheats the toner or the printing material. In microwave application zone 3 of microwave applicator 2, the printing material is heated by microwave radiation such that sufficient heat is transferred to the preheated toner, in order to cause said toner to fuse. The toner, which is fused to printing material 4, is moved out of the microwave application zone through slit 7, at which time ultraviolet radiation of gas-discharge lamp 9 acts on said toner. As a result, the fusing process of toner to printing material 4 is completed. In an advantageous manner, the toner may be cross-linked by UV radiation in this case. This causes the ultraviolet radiation to trigger a chemical reaction of the toner, which, in addition to fusing, causes the toner to undergo a chemical change in such a manner that it is cross-linked on printing material 4. Consequently, a particularly stable printed image is created on printing material 4. This printed image cannot be damaged, for example, by the renewed application of microwave radiation from a microwave applicator 2. This is of particular advantage regarding the quality of the printed image when a duplex printing process used.

FIG. 2 shows a diagram of a side elevation of a fusing device 1, which comprises sliding gas-discharge lamps 8 and 8′ provided outside a microwave applicator 2. The same reference numbers as in FIG. 1 are used for the same elements. In the embodiment shown here, gas-discharge lamps 8 and 8′ are energized by microwave radiation exiting from microwave application zone 3 of microwave applicator 2 in order to emit electromagnetic radiation. In this case, microwave radiation may exit, for example, through slit 6 in panel 12 of the microwave applicator. By energizing gas-discharge lamps 8, 8′ with the use of exiting microwave radiation, this leakage radiation may be used in a favorable manner to at least aid the fusing process. In addition to gas-discharge lamps 8, 8′, which represent absorber elements absorbing exiting microwave radiation, this configuration comprises filter structures 10. These filter structures 10 can further reduce leakage radiation in a larger perimeter of fusing device 1.

A microwave field exists between individual filter structures 10. As depicted here, gas-discharge lamps 8, 8′ can be moved along a slide 23. In the case shown here, shifting takes place in a direction parallel to transport direction 5 of printing material 4. However, shifting in a direction perpendicular thereto is possible. Generally, microwave radiation intensity decreases as the distance from microwave applicator 2 increases. Consequently, by sliding gas-discharge lamps 8, 8′, the intensity of microwave radiation acting on gas-discharge lamps 8, 8′ can be regulated. The electromagnetic radiation emitted through gas-discharge lamps 8, 8′ is directly correlated with the intensity of the microwave radiation acting on said lamps. Depending on the density or thickness of a toner layer on printing material 4, electromagnetic radiation with appropriately adapted intensity may act on the toner. In the case illustrated here, the emitted electromagnetic radiation is infrared radiation. Consequently, depending on the toner density, a gas-discharge lamp 8 or 8′ can be shifted into regions of appropriate field strength of the exiting microwave radiation. In this manner, the emitted infrared radiation is adapted to the density or thickness of the toner material. As a result of this, the toner is preheated even before it enters microwave application zone 3. Less microwave radiation is required for further fixing the toner; generally, the energy required for generating microwave radiation is utilized better. Not illustrated in this figure but equally possible are additional or alternative gas-discharge lamps 9, 9′, which, viewed in transport direction 5 of printing material 4, are located downstream of microwave applicator 2. As already explained regarding FIG. 1, these gas-discharge lamps 9, 9′ may emit UV radiation, for example, and thus at least aid the fixing process or, if cross-linkable toners are used, cross-link the toner on the surface of printing material 4.

FIG. 3 is a schematic illustration of fusing device 1, which comprises a microwave applicator 2 having different panels 11, 12. Again, the same elements have the same reference numbers as in the previous figures.

Printing material 4 having a not-illustrated toner layer is passed along transport path 5 through microwave application zone 3 of microwave applicator 2. Gas-discharge lamps 8, 8′ and 9, 9′ are provided upstream and downstream of the microwave application zone. Gas-discharge lamps 8, 8′ provided upstream of microwave application zone 3 absorb microwave radiation, which exits through slit section 6 from microwave application zone 3, and emit—due to being energized by microwave radiation—infrared radiation that preheats the toner on printing material 4. Gas-discharge lamps 9, 9′ provided downstream of microwave application zone 3 absorb microwaves which exit through slit 7 of microwave applicator 2, and emit UV radiation, which at least aids the fusing process of the toner to the printing material 4, or, if toner that can be cross-linked by UV radiation is used, cross-links the toner on the surface of printing material 4.

Depending on the density or thickness of the toner on printing material 4, different infrared radiation and/or UV radiation intensities are required. These required intensities of emitted radiation can be achieved by changing the intensities of gas-discharge lamps 8, 8′, 9, 9′.

The intensity of microwave radiation exiting through slits 6 and 7 is a function of the slit height of slits 6 and 7. Depending on the required intensity of the microwave radiation, panels 11, 12 of microwave applicator 2 are moved along slides 13 and 14. In this manner, the slit height of slits 6 and 7 may be adapted, and more or less microwave radiation may exit from microwave application zone 3. In particular, it is possible to slide these panels 11, 12 of microwave applicator 2 in different ways. Advantageously, in order to energize gas-discharge lamps 8, 8′, 9, 9′, more microwave radiation should exit from slits 6 and 7 than in a comparable fusing device 1, which comprises absorber elements that are not configured as gas-discharge lamps 8, 9. Consequently, in the illustrated case, the probability of collisions of printing material 4 with lateral panels 11, 12 of microwave applicator 2 is minimized.

FIG. 4 shows a fusing device 1 with sliding filter elements 15. The same reference numbers are used for the same elements as in the previous description of the figures. As in the previous description of the figures, a printing material 4 is passed along a transport direction 5 through a microwave applicator 2 of a fusing device 1. In this case, in the zone upstream of microwave application zone 3 of microwave applicator 2, gas-discharge lamps 8, 8′ are provided which absorb microwave radiation exiting from slit 6 and emit electromagnetic radiation in particular in the infrared region. Various filter elements 10 may be provided in the perimeter outside microwave applicator 2. In particular, it may also be possible to provide gas-discharge lamps 9, 9′ (not shown in this drawing) on the side downstream of microwave applicator 2.

In the zone of gas-discharge lamps 8 and 8′ upstream of microwave applicator 2, two sliding filter elements 15 are provided which can be moved along slides 16 and 17. The direction of this shift is perpendicular to the plane of the transport direction 5 of printing material 4. However, other embodiments are conceivable, in which case slides 16, 17 are located on a plane parallel to transport direction 5.

The intensity of microwave radiation exiting through slit 6 is affected by the positions of filter elements 10 and 15. Thus, a higher intensity of microwave radiation acts on gas-discharge lamps 8, 8′ if filter elements 15 are moved away from the plane of the transport path of printing material 4. A movement toward the plane of the transport path represents a reduction of the intensity of the microwave radiation acting on gas-discharge lamps 8, 8′. As described above, this affects the intensity of the infrared radiation emitted by gas-discharge lamps 8, 8′. It is also possible to provide adjustable filter elements on the side of microwave applicator 2, said filter elements being located downstream of the microwave applicator, viewed in transport direction 5 of printing material 4. In this case, the intensity can be affected by electromagnetic radiation, e.g., UV radiation emitted by gas-discharge lamps 9, 9′. In this manner, the infrared radiation and UV radiation can be adapted advantageously to the thickness or density of the toner.

FIG. 5 shows a fusing device which is substantially similar to the fusing devices described in the previous figures. In addition, or alternatively, this fusing device 1 comprises a coupling element 18 in a panel 12 of microwave applicator 2, said panel being able to stop microwave radiation from microwave application zone 3 of microwave applicator 2 in the zone outside microwave applicator 2 in the vicinity of a gas-discharge lamp 8. The coupling element 18 shown here is an electrical conductor 18. In an alternative embodiment, a diaphragm could be provided which, as a function of its diameter, can stop microwave radiation from microwave application zone 3 in the zone of gas-discharge lamp 8.

Depending on the length with which electrical conductor 18 extends into microwave application zone 13, microwave radiation from microwave application zone 3 is guided into the zone outside microwave applicator 2. This microwave radiation then acts, in addition to microwave radiation exiting from slit 6 of microwave applicator 2, on gas-discharge lamp 8 and energizes said lamp to emit infrared radiation. The farther electrical conductor 18 extends into microwave application zone 3, the greater is the microwave power that is removed from said microwave application zone. In this manner, the intensity of infrared radiation emitted by gas-discharge lamp 8 can also be increased. Correspondingly, the emitted infrared radiation can be reduced if electrical conductor 18 is retracted from the region of microwave application zone 2. In this way, an adaptation of infrared radiation acting on the toner on printing material 4 is possible. Not illustrated here, but covered by the inventive idea, are gas-discharge lamps 9 and 9′, which are located on the side downstream of microwave applicator 2 and emit, for example, UV radiation having an intensity which can be regulated by means of a second electrical conductor 18 in panel 11.

FIG. 6 shows a fusing device which is designed similarly as the previous fusing devices and which comprises diaphragms 19, 20, which can be adjusted around gas-discharge lamps 8, 8′ and, in so doing, can reduce the intensity of microwave radiation acting on gas-discharge lamps 8, 8′ as a function of the extent of shielding of the applied to gas-discharge lamps 8, 8′. To achieve this, diaphragms 19, 20 are adapted cylindrically to the form of gas-discharge lamps 8, 8′ and can be rotated about said lamps. In so doing, said diaphragms have an opening through which microwave radiation can act on gas-discharge lamps 8, 8′. Rotatable diaphragms 19, 30 can be slid in radial direction 21 and 22 about gas-discharge lamps 8, 8′. Depending on the position of the diaphragms, more or less microwave radiation may act on gas-discharge lamps 8 and 8′, and thus more or less infrared radiation is emitted by gas-discharge lamps 8 and 8′.

In particular, it is possible in the case of each described device modification to use electrodes to bias gas-discharge lamps 8, 8′, 9, 9′ and, by increasing or decreasing this bias, to adapt the emitted electromagnetic radiation to specific requirements. These requirements may refer to the layer thickness or density of a toner or, more generally, to a printing agent on printing material 4. If a thicker layer of toner material is on printing material 4, it may be necessary to allow more UV radiation or more infrared radiation to be emitted by gas-discharge lamps 8, 8′, 9, 9′. This can be ensured by an increased bias. The intensity of the radiation can also be adapted to various types of printing agents and/or printing materials; the same may be achieved by adapting the composition of the gas of gas-discharge lamps 8, 8′. In particular, by favorably increasing the bias of gas discharge lamps 8, 8′, 9, 9′, the absorption properties of gas-discharge lamps 8, 8′, 9, 9′ regarding microwave radiation are improved.

Alternatively, it is also possible to use gas-discharge lamps 8, 8′, 9, 9′ which operate without electrodes. In this case, the gas of gas-discharge lamps 8, 8′, 9, 9′ is excited only by microwave radiation exiting form microwave applicator 2 for the emission of electromagnetic radiation.

Likewise, combinations of various device features as shown in FIGS. 1-6 are conceivable. In any event, the device features presented here can be used to improve the degree of effectiveness of fusing device 1 or, more generally, the heating device, because leakage radiation from the microwave applicator exiting through slits 6, 7 from microwave application zone 3 is not simply absorbed by absorber elements, but this absorbed microwave radiation can be utilized by gas-discharge lamps 8, 8′, 9, 9′ in that said microwave radiation is used to excite the gas of gas-discharge lamps 8, 8′, 9, 9′ in such a manner that said lamps emit electromagnetic radiation which can be used for the fusing process or for heating a printing agent or a toner. In a particularly advantageous manner, the toner can initially be heated by infrared radiation, partially fused to printing material 4 by microwave radiation within microwave application zone 3, and finally cross-linked by UV radiation on printing material 4.

Claims

1-31. (canceled)

32. A heating device for heating at least one printing agent on a printing material which is moved along a transport path through said heating device, the heating device comprising: at least one microwave applicator and at least one microwave absorber element in an outer perimeter of the microwave applicator, wherein at least one microwave absorber element is an irradiation device which absorbs microwave radiation and emits electromagnetic radiation.

33. A heating device as in claim 32, wherein the irradiation device is a gas-discharge lamp.

34. A heating device as in claim 32, wherein the irradiation device is provided in a region of the transport path of the printing material upstream of the microwave applicator and is energized by exciting microwave radiation to emit electromagnetic radiation substantially in a visible region of a spectrum.

35. A heating device as in claim 32, wherein the irradiation device is provided in a region of the transport path of the printing material upstream of the microwave applicator and is energized by microwave radiation exiting from the microwave applicator for the emission of electromagnetic radiation substantially in an infrared region of a spectrum.

36. A heating device as in claim 32, wherein the irradiation device is provided in a region of the transport path of the printing material downstream of the microwave applicator and is energized by microwave radiation exiting from the microwave applicator for the emission of electromagnetic radiation substantially in a ultraviolet region of a spectrum.

37. A heating device as in claim 32, wherein a printing agent is used, which can be cross-linked by UV radiation.

38. A heating device as in claim 32, wherein at least one adjustment element is provided for changing the microwave radiation acting on the irradiation device.

39. A heating device as in claim 37, wherein the printing agent is a toner.

40. A method for heating at least one printing agent on a printing material which is moved along a transport path through at least one microwave applicator, the method comprising: irradiating the printing material and/or the printing agent with microwave radiation, wherein the microwave radiation exits from the microwave applicator and is absorbed by at least one microwave absorber element;absorption of the exiting microwave radiation by a microwave absorber element configured as an irradiation device;energizing the irradiation device by microwave radiation;emitting electromagnetic radiation by the irradiation device as a result of being energized by microwave radiation; andapplying the electromagnetic radiation emitted by the irradiation device onto the printing agent and/or the printing material to at least enhance a heating process.