JP2008052032A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power saving image forming apparatus always supplying stable power by a thermoelectric power generating element, supplying power until the inside of a machine is cooled even when power is turned off and to prevent problems such as damage to an electric part or toner blocking due to temperature rise inside the machine in the image forming apparatus provided with a fixing unit of a heat fixing system and also provided with the thermoelectric power generating element carrying out generation of power by using excessive heat in the fixing unit. <P>SOLUTION: The image forming apparatus is provided with the fixing unit heat-fixing a toner image transferred on a recording medium and the thermoelectric power generation element which can carry out generation of power by using the heat in the fixing unit and also supply the generated power. One side of the thermoelectric element is installed in the vicinity of an outside wall of the image forming apparatus and another one is installed to be brought into contact with a heat transmission means transmitting the heat in the fixing unit to the thermoelectric power generating element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine that forms an image using an electrophotographic method, and particularly includes a heat fixing type fixing device, and can generate power using the heat of the fixing device. The present invention relates to an image forming apparatus including a thermoelectric generator.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines, printers, and facsimiles that perform image formation using an electrophotographic method, a thermal fixing method has been widely adopted as a means for fixing an unfixed toner image on a recording medium.

  In a fixing device using such a heat fixing method, it is necessary to heat a fixing roller having a large heat capacity in order to sufficiently fix an unfixed toner image on a recording medium conveyed one after another. Need.

  The heat generated here escapes to the periphery of the fixing device due to the opening for conveying the recording medium, heat transfer, etc., causing the temperature inside the machine to rise, causing malfunction and damage of electrical components, toner blocking, etc. It was.

  As countermeasures, many fans are arranged to discharge excess heat outside the machine so that heat does not escape from the fixing device into the main body.

  In addition, in recent years, the demand for energy-saving technology has been increasing from the viewpoint of environmental problems, and elements that reduce the power consumption by using thermoelectric conversion to generate electric power using the heat of the heat fixing device. Development is underway.

  Here, thermoelectric conversion is the use of the Seebeck effect in which thermoelectromotive force is generated at both ends when a temperature difference is given to two different types of metals or thermoelectric conversion materials such as a p-type semiconductor and an n-type semiconductor. This is a technology that converts power directly.

  FIG. 5 and FIG. 6 show an apparatus configuration diagram of an example of the arrangement of conventional thermoelectric power generation elements.

Regarding the application of this thermoelectric power generation element to an image forming apparatus, as shown in FIG. 5, a thermoelectric power generation element is arranged in the vicinity of a high temperature portion of a fixing device, and heat energy is directly obtained from the fixing device to obtain electric power. (For example, refer to Patent Document 1), as shown in FIG. 6, a thermoelectric power generation element is provided in a downstream conveyance path of a fixing device, and electric power is obtained by using thermal energy of a recording medium after fixing. (For example, refer to Patent Document 2).
Japanese Patent Laid-Open No. 02-217787 JP 2005-062465 A

  However, the exhaust heat by the exhaust heat fan works effectively when the power is turned on, but when the power is turned off, the exhaust heat fan also stops at the same time, and the heat from the fixing device stays in the machine, and the temperature rise in the machine is the same as described above. This may cause malfunction and damage of electrical parts, toner blocking, and the like.

  As a countermeasure, the above-mentioned thermoelectric power generation element is arranged in the machine, and power is generated by the temperature difference between the front and back of the thermoelectric power generation element. However, when a thermoelectric power generation element is arranged near the fixing device as in the past, heat actually flows into the low temperature surface side of the thermoelectric power generation element. In addition, it is difficult to always ensure a temperature difference between the front and back because the thermoelectric power generation element itself has high thermal conductivity or is affected by heat generation of the thermoelectric power generation element itself. As a result, it has been very difficult to supply stable power.

  Therefore, in the present invention, in an image forming apparatus provided with a heat fixing type fixing device and having a thermoelectric power generation element capable of generating power using excess heat of the fixing device, a stable electric power is always supplied by the thermoelectric power generation element. It is possible to supply a power-saving image forming apparatus, and even when the power is turned off, power can be supplied until the inside of the machine cools down, preventing problems such as damage to electrical components and toner blocking due to temperature rise in the machine. The purpose is to do.

The present invention relates to a fixing device that heats and fixes a toner image transferred onto a recording medium, and an image that includes a thermoelectric power generation element that generates power using the heat of the heat fixing device and can supply the generated power. In the forming apparatus, one side of the thermoelectric power generation element is disposed in the vicinity of the outer wall of the image forming apparatus, and the other side is disposed so as to be in contact with a heat transfer means that transfers heat of the fixing device to the thermoelectric power generation element.

  Here, the vicinity of the outer wall of the image forming apparatus is a position where the temperature difference from the outside air is 10 ° C. or less.

  The image forming apparatus is characterized in that the thermoelectric power generation element is disposed in the vicinity of an outer wall near the fixing device.

  Further, when the image forming apparatus has a heat exhaust port for discharging the heat in the image forming apparatus to the outside of the apparatus on the same surface as the outer wall surface on which the thermoelectric power generation element is disposed, the image forming apparatus removes the thermoelectric power generation element. It is arranged below the mouth.

  In addition, when the paper discharge unit that discharges the recording medium to the outside of the image forming apparatus is on the side of the image forming apparatus, the image forming apparatus is located near the outer wall of the side surface on which the paper discharge unit is provided. In addition, it is characterized in that it is disposed below the paper discharge unit.

  According to the present invention, in an image forming apparatus that includes a heat fixing type fixing device and includes a thermoelectric power generation element that can generate power by using excess heat of the fixing device, stable power is always supplied by the thermoelectric power generation element. It is possible to supply a power-saving image forming apparatus, and even when the power is turned off, power can be supplied until the inside of the machine cools down, preventing problems such as damage to electrical components and toner blocking due to temperature rise in the machine. It becomes possible to do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention. In the present embodiment, a system in which the thermoelectric generator 9 is disposed below the paper discharge tray 65 and the fixing exhaust heat fan 83 is driven by the electric power obtained by the thermoelectric generator 9 will be described.

  In FIG. 1, a photosensitive drum 1 as an image bearing pair is rotatably supported, and around the photosensitive drum 1, a pre-exposure lamp, a corona electric resistance device, a laser exposure optical system 2, a potential sensor, an intermediate transfer body 3, and a cleaning device. 4 and the rotating type developing body 5 are arranged.

  The rotatable rotary developing member 5 has four color developing devices: a black developing device 5K, a yellow developing device 5Y, a magenta developing device 5M, and a cyan developing device 5C. The rotary developer 5 rotates around a cylindrical rotation shaft provided at the center of the rotary developer in the counterclockwise direction indicated by an arrow a in the drawing, and a developer of a desired color is connected to the photosensitive drum 1 when necessary. It is possible to move to the opposite development position.

  In the laser exposure optical system 2, the image signal from the reader unit is converted into an optical signal by the laser output unit, and the laser beam converted into the optical signal is reflected by the polygon mirror, and passes through the lens and each reflecting mirror to the photosensitive drum 1. Projected onto the surface.

  At the time of image formation of the printer unit, the photosensitive drum 1 is rotated, and the photosensitive drum after being neutralized by the pre-exposure lamp is uniformly charged by a charger, and the light image E of the first color is irradiated to form a latent image on the photosensitive drum. Form. Next, the latent image on the photosensitive drum is developed by a developing device, and a toner image using a resin and a pigment as a base is formed on the photosensitive drum.

  Thereafter, the toner image formed on the photosensitive drum is primarily transferred to the intermediate transfer member 3.

  When the development of the first color is completed, the rotary developer 5 is rotated by 90 ° in the direction of arrow a in the figure, the developer of the second color is moved to the development position facing the photosensitive drum 1, the primary transfer is completed, and the cleaning device 4. As in the first color, the photosensitive drum 1 cleaned in this manner repeats the second, third, fourth and latent images, development, and primary transfer, and sequentially superimposes the toner images of the respective colors on the intermediate transfer body 3.

  Here, the toner in the developing device is replenished as needed from the toner storage portion at a desired timing so as to keep the toner ratio (or toner amount) in the developing device constant.

  On the other hand, the recording medium is conveyed one by one from the storage units 61, 62, 63, 64 by the respective paper feeding means 71, 72, 73, 74, and the skew is corrected by the registration rollers 75, and at a desired timing. It is conveyed to the secondary transfer unit 76.

  The recording medium onto which the toner image has been transferred by the secondary transfer unit 76 passes through the transport unit 77 and is transported to the fixing device 8.

  In the fixing device 8, the heating roller 81 and the pressure roller 82 are in pressure contact with each other, and the unfixed toner image on the recording medium is heated and pressed to be fixed by feeding the recording medium to the rollers 81 and 82. The paper is discharged to the paper discharge tray 65.

  Here, heat generated in the fixing device 8 other than heat necessary for fixing escapes to the periphery of the fixing device 8 and increases its peripheral temperature.

  Due to this heat, the electrical components are damaged, the toner is blocked, and the image formation is adversely affected. Therefore, excess heat that escapes around the fixing device 8 is generated. A fixing exhaust heat fan 83 for exhausting heat outside the apparatus is provided so as not to go around toner such as electrical parts and developing units, and around image forming such as a photosensitive drum.

  However, since the fixing exhaust heat fan 83 can always operate during normal operation, excess heat from the fixing device 8 can be exhausted to the outside of the apparatus. However, when the power is turned off, the fixing exhaust heat fan 83 also stops at the same time. The heat escaping from the fixing device 8 is trapped in the apparatus, causing problems such as damage to the electrical components and toner blocking described above.

  Therefore, in the present invention, power is supplied to the fixing exhaust heat fan not only from the main power supply but also from the thermoelectric generator 9. Here, a thermoelectric power generation element uses the Seebeck effect in which a thermoelectromotive force is generated at both ends when a temperature difference is given to two different types of metals or thermoelectric conversion materials such as a p-type semiconductor and an n-type semiconductor. Can be directly converted into electric power, and power is generated using the heat of the fixing device 8. Therefore, even when the power is off, the fixing exhaust heat fan 83 can be supplied with power while the fixing device 8 is hot. Yes, the fixing exhaust heat fan 83 continues to rotate and automatically stops when the temperature of the fixing device 8 decreases. At this time, the temperature inside the machine has already been sufficiently lowered, and the above-mentioned problems such as electrical component breakage and toner blocking are not affected.

  Here, power supply to the fixing exhaust heat fan 83 will be described.

  FIG. 3 shows a block diagram of power supply to a fan according to an example of the present invention.

  As shown in FIG. 3, the fixing exhaust heat fan 83 is normally driven by being supplied with electric power from the main power source. On the other hand, the thermoelectric power generating element receiving heat by the fixing device 8 generates power by the temperature difference between the front and back surfaces and charges the power storage circuit. When the power storage circuit is sufficiently charged, power is supplied to the fixing exhaust heat fan from the power storage circuit, and the power supplied from the main power supply is suppressed by voltage conversion or is completely stopped. By doing so, the fixing exhaust heat fan 83 can always rotate stably. When the power is turned off, the instantaneous interruption circuit determines the voltage level, and switches the switch so as to supply electric power from the power storage circuit to the fixing heat exhaust fan 83. As a result, the fixing exhaust heat fan 83 can be rotated for a predetermined time even after a momentary interruption. At this time, until the heat of the fixing device 8 escapes and cools, power generation is also performed by the thermoelectric power generation element 9, so that the heat storage circuit charges the thermoelectric power generation element 9 and supplies the power already stored. Since it is possible, the fixing exhaust heat fan 83 can be turned on for a fixed time until the fixing device 8 cools down.

  Here, as the heat storage circuit, a dischargeable capacitor or the like may be used.

  Next, the arrangement of the thermoelectric generator elements will be described in detail.

  FIG. 2 shows a cross-sectional view of the vicinity of the thermoelectric generator 9 and the heat transfer means 91.

  As shown in FIG. 2, in the present invention, a thermoelectric power generation element 9 is provided in the vicinity of the outer wall, and a louver (opening) 93 is provided on the outer wall so that the low temperature surface side can directly touch the outside air. As described above, the thermoelectric power generation element 9 has a high thermal conductivity and is easily affected by heat from the high temperature surface side, and the temperature on the low temperature surface side becomes hot due to the heat generated by the element itself. This is because a sufficient heat radiation space is required to keep the temperature on the low temperature surface side as low as possible.

  Further, since it is necessary to always keep the high temperature surface side at a high temperature, a heat transfer means 91 is provided to transfer heat from the fixing device 8 to the thermoelectric generation element 9, and the high temperature surface side of the thermoelectric generation element 9 is brought into contact with the heat transfer means. By keeping it in this state, it is possible to always maintain a high temperature during normal operation, and to maintain a high temperature for a long time even when the power is turned off.

  Here, a metal plate having a high thermal conductivity may be used for the heat transfer means 91.

  Furthermore, in order to always maintain the temperature difference between the front and back surfaces, it is necessary to prevent heat from flowing in from the high temperature surface side. In this embodiment, a heat insulating material 94 is provided around the thermoelectric generator 9.

  The vicinity of the outer wall, which is the arrangement area of the thermoelectric generator 9, can be more effectively dissipated by placing it in a space closer to the outside air, and the temperature difference from the outside air is 10 because it is better to place in a temperature environment as low as possible. It is desirable that the temperature is not higher than ° C. Here, the outside air temperature is a temperature in the vicinity of the main body of the image forming apparatus, for example, an average temperature in a space one meter apart from the outer wall of the main body of the image forming apparatus.

  Further, it is desirable that the thermoelectric power generation element 9 be disposed near the outer wall near the fixing device 8. This is because the transmission distance by the heat transfer means 91 is shortened as much as possible to minimize the loss due to heat dissipation of the heat energy and to prevent the temperature rise in the apparatus such as around the image formation due to the heat dissipation of the heat transfer means 91.

  Usually, the outer wall of the image forming apparatus is provided with a plurality of heat exhaust ports for exhausting heat inside the apparatus in addition to a heat exhaust port (louver) by the fixing exhaust heat fan 83. If the thermoelectric power generation element 9 is provided near and above the heat exhaust port, the low temperature surface side is warmed due to the effect of exhaust heat. Therefore, in the present invention, the thermoelectric power generation element 9 is preferably disposed below the heat exhaust port. .

  Furthermore, when the paper discharge unit that discharges the recording medium to the outside of the image forming apparatus is on the side of the image forming apparatus, the thermoelectric generator 9 is located near the outer wall of the side on which the paper discharge unit is provided, and is discharged. It is desirable to arrange it below the paper tray 65. This is because a user who does not have enough space for installing the image forming apparatus installs the back and side surfaces close to the wall, etc. This is because if there is a wall immediately before, the heat will be trapped there and the low temperature side may not be kept at a sufficiently low temperature. On the other hand, when the paper discharge tray 65 is on the side surface, a paper discharge space is required, so that the side surface is not placed close to a wall or the like. Therefore, a heat radiation space corresponding to at least the length of the paper discharge tray 65 is obtained on the side surface, which is advantageous in keeping the low temperature surface side at a low temperature. However, when the thermoelectric generator 9 is disposed above the paper discharge tray 65, the recording medium heated by the fixing device 8 is conveyed onto the paper discharge tray. Therefore, the low temperature surface side is affected by the heat of the recording medium. There is a risk that it cannot be kept at a sufficiently low temperature. Therefore, it is desirable to dispose the thermoelectric generator 9 on the lower side of the paper discharge tray 65.

  As described above, the arrangement of the thermoelectric power generation elements 9 has been described so far, but in order to obtain more power, a plurality of thermoelectric power generation elements 9 may be arranged in series. Although there are individual differences in thermoelectric power generation elements, for example, in this embodiment, a plurality of (here, ten) thermoelectric power generation elements are arranged in series and used so that the temperature on the low-temperature surface side is 50 ° C. and high By setting the temperature of the surface side to 90 ° C. and a temperature difference of 40 °, an electric power of 12V can be obtained, and the image forming apparatus including the fixing device 8 that controls the temperature of the heating roller at 200 ° C. When used in the above environment, the temperature difference can be sufficiently obtained by adopting the configuration of the present invention. For example, when a 12V fan is driven, stable power supply is possible.

  In addition, by providing a heat insulating member also around the heat transfer means 91, heat radiation from the heat transfer member 91 can be suppressed, so that the temperature on the high temperature surface side can be kept higher and the power generation effect is improved. Needless to say.

  Furthermore, as shown in FIG. 4, the heat transfer means 91 has a structure in which the portion inside the fixing device 8 is formed to be uneven, thereby increasing the contact area with the heat flow and increasing the heat collection effect. Since it becomes possible to transmit more heat to the hot surface side of 9, the power generation effect is also improved. Here, the heat insulating member 84 is formed by penetrating the fixing heat insulating cover 84, but here also, the gap between the fixing heat insulating cover 84 and the heat transfer member 91 is filled with a heat insulating material, so It is possible to prevent the heat from being released outside the fixing device more than necessary.

  In addition, by providing a heat radiating plate or the like on the low temperature surface side of the thermoelectric power generation element 9, the heat radiation efficiency is increased and the temperature can be maintained at a lower temperature.

  In addition, the system in which the fixing exhaust heat fan is driven by the electric power obtained from the thermoelectric generator 9 has been described so far. Is applicable. Further, from the viewpoint of reducing power consumption without considering the time when the power is turned off, the electric component can be operated by the electric power generated using the remaining heat, and thus can be applied to all electric components.

  As described above, according to the present invention, in an image forming apparatus that includes a fixing device of a thermal fixing type and includes a thermoelectric power generation element that can generate electric power using excess heat of the fixing device, the thermoelectric power generation element always provides stable power. A power-saving image forming apparatus that can supply power and can supply power until the inside of the machine cools down even when the power is turned off. It becomes possible to prevent problems.

1 is a main cross-sectional view of an image forming apparatus that is an example of an embodiment of the present invention. FIG. 2 is a cross-sectional view of the vicinity of a thermoelectric generator and heat transfer means in the image forming apparatus of FIG. 1. The block diagram of the electric power supply to the fan of an example of this invention. FIG. 2 is a cross-sectional view of the vicinity of a fixing device and heat transfer means in the image forming apparatus of FIG. 1. The apparatus block diagram which shows an example of arrangement | positioning of the conventional thermoelectric power generation element (Unexamined-Japanese-Patent No. 02-217876). The apparatus block diagram which shows an example of arrangement | positioning of the conventional thermoelectric power generation element (Unexamined-Japanese-Patent No. 2004-272131).

Explanation of symbols

65 Discharge tray 8 Fixing device 81 Heating roller 82 Pressure roller 83 Fixing heat exhaust fan 84 Fixing heat insulating cover 9 Thermoelectric power generation element 91 Heat transfer means 92 Outer wall 93 Louver 94 Heat insulating material

Claims (5)

An image forming apparatus including a fixing device that heat-fixes a toner image transferred onto a recording medium, and a thermoelectric power generation element that generates power using heat of the fixing device and can supply the generated power.
An image forming apparatus, wherein one side of the thermoelectric power generation element is disposed in the vicinity of the outer wall of the image forming apparatus, and the other is disposed so as to contact a heat transfer means that transfers heat of the fixing device to the thermoelectric power generation element. 2. The image forming apparatus according to claim 1, wherein the temperature difference between the vicinity of the outer wall of the image forming apparatus and outside air is 10 ° C. or less. 3. The image forming apparatus according to claim 1, wherein the thermoelectric power generation element is disposed in the vicinity of an outer wall in the vicinity of the fixing device. The image forming apparatus according to any one of claims 1 to 3, wherein when there is a heat exhaust port for discharging the heat in the image forming apparatus to the outside of the apparatus on the same surface as the outer wall surface on which the thermoelectric generation element is disposed. An image forming apparatus, wherein the thermoelectric generator is disposed below the heat exhaust port. 5. The image forming apparatus according to claim 1, wherein when the paper discharge unit that discharges the recording medium to the outside of the image forming apparatus is on the side of the image forming apparatus, the thermoelectric power generation element is provided with the paper discharge unit. An image forming apparatus, wherein the image forming apparatus is disposed in the vicinity of an outer wall on a side surface and below the paper discharge unit.

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