JP2008009320A - Flash fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flash fixing device capable of fixing a toner image transferred to a recording medium with simple constitution by efficiently radiating high energy without causing burnt deposits or gas on the surface of toner and without causing irregularities in an image. <P>SOLUTION: Eight flash lamps 1a to 1h of a flash fixing unit 13 are divided into a first flash lamp group (1a and 1e), a second flash lamp group (1b and 1f) and a third flash lamp group (1c, 1d, 1g and 1h), and the first to the third flash lamp groups are made to emit light in different timing in order, whereby light energy radiated the last is made the largest and also light emission is controlled so that the lag of the light emitting timing of the respective flash lamp groups may be shorter than the light emitting time thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a flash fixing device.

  In a printer that forms a toner image such as a dry electrophotographic system, after a toner image formed with powdered toner is transferred onto a recording medium, the toner image is transferred onto the recording medium (powder toner on the recording medium). The toner image is fixed on the recording medium by applying fixing energy and melting the powder toner.

  In high-speed printers, flash fixing using flash light by a non-contact type flash lamp is used as a method for providing the fixing energy. The non-contact type fixing method is suitable for high-speed printers because it can apply high energy without affecting the conveyance of the recording medium.

  High-speed printers are mainly used for printing forms, and in the past, most of them were monochrome, but the demand for full color is gradually increasing due to market needs. Color image formation by dry electrophotography can be achieved by superimposing toner images of C, M, Y, and K colors, but the amount of toner transferred to the recording medium is inevitably increased compared to monochrome. Therefore, in order to secure the fixability of the toner image, a fixing device that concentrates flash lamps and supplies high energy is essential.

  6A and 6B show a changing toner surface temperature and sheet interface temperature, and FIG. 6B shows an image of toner in a fixing device that supplies high energy by one flash irradiation. As shown in both figures, when a large amount of energy is applied at one time by one flash irradiation in (1), the surface temperature of the toner rises greatly in (2), and the powder yellow toner 51 becomes a molten yellow toner 53. In (3), the toner surface temperature reaches a peak, and the powder magenta toner 52 also becomes the molten magenta toner 54. However, since the toner surface temperature exceeds the gas generation temperature, gas is generated.

  Thus, in order to realize a high-speed and high-definition color printer, it is necessary to increase the input energy per unit area by increasing the number of lamps compared to the conventional printer. However, if a large amount of energy is input at once, the degree of absorption differs depending on the physical properties of some recording media, and there is a medium with excessive energy, so there is an increase in scoring and gas on the toner surface. This causes problems such as a decrease in performance and a shortened life of the smoke removal filter.

  In order to solve this problem, a method is proposed in which an amount of energy that does not scatter toner is input and preliminarily worn, and then a larger amount of energy than that at the time of the assumption is applied to perform main fixing (see Patent Document 1, for example). ing. 7A and 7B, when the flash energy irradiation is performed in two steps as in Patent Document 1, (A) shows the changing toner surface temperature and paper interface temperature, and (B) shows an image of the toner.

  In the case of Patent Document 1, as shown in FIG. 8, the energy of the energy amount E1 is irradiated by the first flash irradiation, and the energy of the energy amount E2 is irradiated by the second flash irradiation. At this time, the delay time from the first flash irradiation to the second flash irradiation is long, and energy is supplied from time T1 when the first flash irradiation ends to time T2 when the second flash irradiation starts. No time occurs. Therefore, the toner surface temperature, the sheet interface temperature, and the toner change as follows.

  In FIG. 7, the first flash irradiation is performed in (1), and in (2), the surface of the powder yellow toner 51 exceeds the toner melting temperature (softening) to become the melted yellow toner 53. The body magenta toner 52 is not melted. In (3), since the supply of energy is interrupted thereafter, the molten yellow toner 53 aggregates due to the surface tension while the toner temperature decreases due to heat dissipation. In (4), the lower layer magenta toner 52 is also pulled by the surface tension of the molten yellow toner 53, and a nest (void) 55 is generated, which disturbs the image.

  In addition, a method (for example, refer to Patent Document 2) in which a flash lamp is irradiated 2 to 5 times at intervals of a delay time of 0.1 to 5 ms has been proposed. 9A and 9B, when the flash energy irradiation of the same amount of energy is performed in five steps as in Patent Document 2, FIG. 9A shows the changing toner surface temperature and paper interface temperature, and FIG. 9B shows the image of the toner. It is.

In FIG. 9, the first lash irradiation is performed in (1), but there is no significant difference between the toner surface temperature 41 and the paper interface temperature 42. Further, since the toner surface temperature 41 has a sufficient margin to the gas generation temperature, it can be irradiated many times until the paper interface temperature 42 reaches the toner melting temperature between (2) and (3). Both the toner 51 and the powder magenta toner 52 are melted to become a melted yellow toner 53 and a melted magenta toner 54. However, as the number of times of irradiation increases, the number of times of heat radiation from the toner also increases, resulting in inefficiency.
Japanese Patent Publication No.55-25667 Japanese Examined Patent Publication No. 62-20544

  As described above, the method of Patent Document 1 has a problem in that a void is generated and the image is disturbed because the delay time of the flash energy input from the assumed wearing to the main fixing is long and the heat radiation time is long. . Further, in the method of Patent Document 2, if the same level of energy is irradiated five times, there is no significant difference between the toner surface and the interface temperature, but there is a problem that the number of heat radiation from the toner increases and efficiency decreases. is there.

  The present invention has been made in order to solve the above-described problems. The fixing of the toner image transferred to the recording medium can be efficiently performed without causing scorching and gas generation on the toner surface, and without disturbing the image. An object of the present invention is to provide a flash fixing apparatus that can be irradiated with high energy and can be realized with a simple configuration.

  In order to achieve the above object, a flash fixing device according to claim 1 includes a flash lamp group including at least one flash lamp, and a flash lamp group including a larger number of flash lamps than the flash lamp group. The light source that fixes the toner image transferred onto the recording medium by irradiation and the flash lamp group including the plurality of flash lamps are finally emitted from the flash lamp group at different light emission timings. And a light emission control means for controlling the light emission for each flash lamp group so that the deviation of the light emission timing is shorter than the light emission time of each of the plurality of flash lamp groups.

  According to the first aspect of the present invention, since the flash lamp group that emits light at the end includes more flash lamps than the other flash lamp groups, the toner image can be fixed by irradiating with large energy at the end.

  The flash fixing device according to claim 2 includes a plurality of flash lamps, and one flash lamp of the plurality of flash lamps irradiates flash light having a larger energy than the other flash lamps to be applied onto the recording medium. The light source for fixing the transferred toner image, and the flash lamp from which the flash light is emitted from each of the plurality of flash lamps, and the flash lamp that irradiates the flash light with the large energy are emitted last, Light emission control means for controlling light emission so that the deviation is shorter than the light emission time of each of the plurality of flash lamps.

  According to the second aspect of the invention, the flash lamp that emits light at the end can fix the toner image by irradiating with larger energy than the other flash lamps.

  The flash fixing device according to claim 3 is the flash fixing device according to claim 1 or 2, wherein the light emission control means causes the last light emission to be emitted for the third time.

  According to the third aspect of the present invention, the light emission of the flash lamp is divided into three times and finally the large energy is irradiated, so that the toner surface temperature does not exceed the gas generation temperature and the temperature difference from the paper sea surface temperature is widened. In addition, the toner image can be fixed most efficiently by keeping the heat radiation time short.

  According to the present invention, the flash light emitted from a plurality of flash lamps or flash lamp groups is irradiated at different timings so that the light energy irradiated last is maximized, and the flash light irradiation timing shifts respectively. Since the light emission of a plurality of flash lamps or a group of flash lamps is controlled so as to be shorter than the flash lamp emission time, a device for fixing a toner image transferred to a recording medium without causing deterioration in image quality can be simplified. The effect that it is realizable with a simple structure is acquired.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a printing apparatus 10 according to the present embodiment. The printing apparatus 10 is an apparatus for forming an image on a recording medium 2 made of continuous paper. The recording medium 2 accommodated in a paper hopper 11 is continuously fed and accommodated in a stacker 12 via a transfer unit 7 and a fixing unit 13. Is done.

  The photosensitive drum 4 rotating in the clockwise direction is uniformly charged by the charger 3, and then an image is exposed by the optical system 5. As a result, an electrostatic latent image corresponding to the image is formed on the photosensitive drum 4.

  The electrostatic latent image formed on the photosensitive drum 4 is developed by the developing device 6. The toner image on the photosensitive drum 4 obtained by development is transferred to the recording medium 2 by the transfer unit 7. After the transfer, the photosensitive drum 4 is neutralized by a static eliminator 9 and residual toner is cleaned by a cleaner plate 8 and a cleaner brush 14.

  The recording medium 2 onto which the toner image has been transferred is flash-fixed by the flash fixing unit 13 and then stored in the stacker 12. The flash control unit 19 controls the light emission (light emission frequency) of the flash lamp 1 by controlling the light emission control power source 35 (see FIG. 3) of the drive circuit of the flash fixing unit 13.

  FIG. 2 shows two different configuration examples of the flash fixing unit 13 and uses the energy obtained by the light emission of the plurality of flash lamps 1 to fix the toner. In FIG. 6A, a plurality of flash lamps 1a to 1d (four in the figure, but not limited to four) are arranged such that the axis intersects the conveyance direction of the recording medium 2. The reflector 20 and the cover glass 21 are disposed. FIG. 2B is another example, and a plurality of flash lamps 1a to 1g (seven in the figure, but not limited to seven) in the flash fixing unit 13. The axis is arranged substantially parallel to the conveyance direction of the recording medium 2.

  In any configuration example, the reflecting plate 20 is provided on the back side of the flash lamp 1 (hereinafter referred to as “1” when the flash lamp is generically described), that is, the recording medium 2 of the flash lamp 1 is conveyed. It surrounds the opposite side of the road and is formed in a shape that opens to the front side (conveyance path side), and reflects the flash light emitted from the flash lamp 1 to the back side to the conveyance path side. Further, each flash lamp 1 is individually lit, but when any flash lamp is lit, the flash light radiated to the recording medium 2 has a substantially uniform light amount (substantially uniform across the front surface of the irradiation range). That is, the shape and the like are adjusted so as to be energy.

  A cover glass 21 is disposed on the front side (conveyance path side) of the flash lamp 1. The cover glass 21 is provided so as to close the opening of the reflection plate 20. The cover glass 21 prevents dust and the like from entering the flash fixing unit 13.

  FIG. 3 shows a driving circuit for flash fixing. Each flash lamp 1 of the flash fixing unit 13 is connected to this driving circuit.

  As shown in FIG. 3, both ends of the flash lamp 1 are connected to a power supply circuit 30. The light emission control power source 35 controlled by the flash control unit 19 (see FIG. 1) charges the capacitor 31 in the power supply circuit 30, and the trigger circuit 34 managed by the light emission control power source passes through the trigger cable line 38. A voltage is applied to the trigger wire 36, and as a result, the Xe gas in the flash lamp 1 is excited to emit light.

  Further, the power supply circuit 30 includes a choke coil 33. By adjusting the inductance of the choke coil 33, the current flowing to the flash lamp 1 is changed, and the inclination and the amount of light of the flash light from the flash lamp 1 are changed. As the peak changes, the flash light emission time also changes. For example, if the choke coil 33 is made larger, the gradient of the change in the amount of flash light increases, and the current flows at a stretch, so that the current increases and the light emission energy increases.

  Next, the operation of the present embodiment will be described. In this embodiment, among the eight flash lamps 1a to 1h shown in FIG. 4A, 1a and 1e are the first flash lamp group, 1b and 1f are the second flash lamp group, 1c, 1d, Let 1g and 1h be the third flash lamp group.

  In this way, the eight flash lamps 1a to 1h are divided into three groups (two, two, and four), light is emitted in order for each group, and irradiation is performed by increasing the number of groups that emit light last. Maximize the amount of energy.

  When the recording of the image on the recording medium 2 is started by the printing apparatus 10, the flash control unit 19 causes the first flash lamp group to emit light for a predetermined time with a predetermined light emission cycle Y as shown in FIG. In addition, the second flash lamp group emits light at a timing delayed by a predetermined delay time X with respect to the light emission timing of the first flash lamp group and at a predetermined light emission period Y for a predetermined time. Each of the flash lamps 1a to 1h is configured such that the three flash lamp groups emit light at a timing delayed by a predetermined delay time X with respect to the light emission timing of the second flash lamp group and at a predetermined light emission period Y. Control is performed so that a signal is transmitted from the light emission control power source 35 connected to the trigger circuit 34.

  At this time, trigger timings 71a and 71b at which the first flash lamp group shown in FIG. 4B emits light, trigger timings 72a and 72b at which the second flash lamp group emits light, and a third flash lamp group emits light. The respective light energy distribution patterns at the trigger timings 73a and 73b correspond to the curve 81a and the curve 81b, the curve 82a and the curve 82b, the curve 83a and the curve 83b, respectively, shown in FIG.

  As shown in FIG. 4C, in this embodiment, the light emission timing shift (that is, the predetermined delay time X) of each flash lamp group is set to be shorter than the light emission time. Since irradiation is performed without interruption, generation of voids due to heat dissipation can be suppressed.

  Here, the control of the lighting timing of the flash lamp 1 by the flash fixing driving circuit will be described with reference to the flowchart shown in FIG. This flow starts when the printing apparatus 10 according to the present embodiment is turned on, and is repeatedly executed every predetermined time.

  First, in step 110, it is determined whether or not toner fixing processing has started. This determination is made based on whether or not the recording medium 2 has been conveyed to the flash fixing unit 13. When the recording medium 2 is conveyed to the flash fixing unit 13, it is determined that the fixing process is started, and the process proceeds to step 120. When the recording medium 2 is not conveyed, the determination of step 110 is repeatedly performed.

  In step 120, the flash lamps 1a and 1e of the first flash lamp group are lit for a predetermined time. In the following step 130, it is determined whether or not a predetermined delay time has elapsed since the lighting of the first flash lamp group. If it has elapsed, the process proceeds to step 140. If not, the determination in step 130 is performed. repeat.

  In step 140, the flash lamps 1b and 1f of the second flash lamp group are lit for a predetermined time. In the subsequent step 150, it is determined whether or not a predetermined delay time has elapsed since the lighting of the second flash lamp group. If it has elapsed, the process proceeds to step 160. If not, the determination in step 150 is performed. repeat.

  In step 160, the flash lamps 1c, 1d, 1g, and 1h of the third flash lamp group are lit for a predetermined time. In the next step 170, it is determined whether or not the toner fixing process is completed. This determination is made based on whether or not a predetermined lighting time has elapsed since the third flash lamp group was turned on. If the predetermined lighting time has elapsed, it is determined that the fixing process has been completed, and the process returns to step 110, waits for the next recording medium 2 to be conveyed, and if it has not elapsed, the determination in step 170 is repeated.

  FIG. 10 is a light energy profile with which the toner is irradiated in the present embodiment. As shown in the figure, the light emission timing shift time X of each flash lamp group is set shorter than the light emission time Z. That is, it is determined that the second flash lamp group emits light after the light energy amount due to light emission of the first flash lamp group reaches a peak and before the light energy amount returns to zero. . Specifically, for example, when the light emission time Z is 1.5 ms, the light emission timing shift time X is preferably 0.5 ms.

  By controlling the light emission timing of each flash lamp group in this way, the light energy is irradiated to the toner without interruption, so that generation of voids due to heat dissipation can be prevented.

  FIGS. 11A and 11B are illustrations of toner surface temperature and paper interface temperature that change, and FIG. 11B is an image of toner when flash energy irradiation by the flash fixing device according to the present embodiment is performed in three steps. . In FIG. 5A, a temperature curve 41 represents a change in toner surface temperature, and a temperature curve 42 represents a change in sheet interface temperature.

  In (1), flash irradiation is performed by the first flash lamp group. In (2), the surface of the powder yellow toner 51 exceeds the toner melting temperature (softening) to become the molten yellow toner 53, but the energy is low and the powder is low. The body magenta toner 52 is not melted. In (3), until the second flash lamp group performs flash irradiation, the toner temperature is reduced by heat radiation, and the molten yellow toner 53 is aggregated due to surface tension. In (4), the powder magenta toner 52 is melted while maintaining the temperature of the molten yellow toner 53 by the flash irradiation of the second flash lamp group, and the paper interface temperature is raised to the toner melting temperature. In (5), the melted magenta toner 54 melted in (4) adheres to the paper 2 and the generation of voids due to toner aggregation is suppressed. Thereafter, the third flash lamp group is fixed again after being melted again by the large flash energy irradiated. As a result, the surface smoothness is improved and a good printing result is obtained.

  As described above, in this embodiment, flash irradiation is performed so that the temperature difference between the toner surface and the paper interface does not widen and the heat radiation time does not increase so that the surface temperature of the toner does not exceed the gas generation temperature. The toner is fixed by irradiating small energy, small energy, and finally large energy in three times.

  In this embodiment, the flash irradiation is performed in three steps, but the present invention is not limited to this. The smaller the number of times, the smaller the number of times, the greater the amount of energy irradiation per time, and the toner surface temperature exceeds the gas generation temperature. This is due to what experience has shown to be the most favorable.

  In this embodiment, the flash lamp is divided into three flash lamp groups, and the number of flash lamps is increased to increase the amount of energy to be irradiated last. However, the present invention is not limited to this method. . By using three flash lamps and increasing the current flowing through one flash lamp, the amount of energy finally irradiated can be increased. In this case, a large current flows by enlarging the choke coil 33 of the power supply circuit 30 connected to the flash lamp that is lit last.

  Table 1 shows a result of comparing the toner fixing property and the gas generation state when the toner is fixed with the same amount of energy in the light emitting method according to the present embodiment and the light emitting method according to the prior art.

表１において、（２）の特許文献１の方法では界面温度は最も高く、トナーの定着性は良好だが、ガス発生が多く、フィルタ寿命が短くなってしまう。また、（３）及び（４）の特許文献２で３回又は５回に分ける方法では、ガス発生は抑えられるが、定着性が低下していく。これに対して、（１）の本実施の形態ではトナー定着性、ガス発生状況の何れも良好であることが分かる。

In Table 1, in the method of Patent Document 1 of (2), the interface temperature is the highest and the fixability of the toner is good, but the gas generation is large and the filter life is shortened. Moreover, in the method divided into 3 times or 5 times in Patent Document 2 of (3) and (4), the gas generation is suppressed, but the fixing property is lowered. On the other hand, in the present embodiment (1), it can be seen that both the toner fixing property and the gas generation state are good.

1 is a schematic configuration diagram of a printing apparatus according to an embodiment. 2A and 2B are diagrams illustrating a configuration example of a flash fixing unit, in which FIG. 3A is a configuration diagram in which an axis of a flash lamp is perpendicular to a sheet conveyance direction, and FIG. It is a schematic block diagram of the drive circuit of the flash fixing unit according to the present embodiment. (A) is a schematic diagram of a flash fixing unit according to the present embodiment, (B) is a timing chart showing light emission timings of the first, second and third flash lamp groups, and (C) is a recording medium supplied. It is a conceptual diagram which shows the distribution pattern of a certain energy. It is a flowchart which shows the flow of control of the lighting timing of a flash lamp. In the fixing device that supplies energy by one flash irradiation, (A) is a changing toner surface temperature and paper interface temperature, and (B) is an image diagram of toner. (A) is a changing toner surface temperature and paper interface temperature, and (B) is an image diagram of toner when flash energy irradiation is performed twice as in Patent Document 1. It is a figure which shows the relationship between the energy amount of flash irradiation in the case of patent document 1, and time. (A) is a changing toner surface temperature and paper interface temperature, and (B) is an image of toner when flash energy irradiation of the same amount of energy is performed in five times as in Patent Document 2. 2 is a light energy profile irradiated to toner in the exemplary embodiment. When the flash energy irradiation by the flash fixing apparatus according to the present embodiment is performed in three steps, (A) is a changing toner surface temperature and paper interface temperature, and (B) is an image diagram of toner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flash lamp 2 Recording medium 10 Printing apparatus 13 Flash fixing unit 20 Reflector 21 Cover glass 30 Power supply circuit 31 Capacitor 33 Choke coil 34 Trigger circuit 35 Light emission control power supply

Claims (3)

A flash lamp group including at least one flash lamp, and a light source including a flash lamp group including a larger number of flash lamps than the flash lamp group and fixing a toner image transferred onto a recording medium by irradiating flash light; ,
The flash lamps from each of the flash lamp groups have different light emission timings, and the flash lamp group including the plurality of flash lamps emits light last, and the light emission timing shift is the light emission time of each of the plurality of flash lamp groups. Light emission control means for controlling light emission for each flash lamp so as to be shorter,
Including flash fixing device. A light source that includes a plurality of flash lamps and that fixes a toner image transferred onto a recording medium by irradiating flash light of one of the plurality of flash lamps with energy greater than that of the other flash lamps; ,
Each of the plurality of flash lamps emits flash light at a different light emission timing, and the flash lamp that irradiates the flash light with the large energy is emitted last, and a light emission timing shift causes light emission of each of the plurality of flash lamps. Light emission control means for controlling light emission so as to be shorter than time;
Including flash fixing device.   The flash fixing device according to claim 1, wherein the light emission control unit causes the last light emission to be performed for the third time.

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