JP2007233327A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing quality of a printed image from deteriorating by preventing the surface temperature of a photoreceptor from rising. <P>SOLUTION: A compressor 1-2 generates and blows a cold blast to the surface of the photoreceptor 4 through a vortex tube 1-1 or to the case of a developing unit 9, a contact member 1-5 for a form 11, a contact member 1-4 for the photoreceptor 4, etc., for cooling. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to an image forming apparatus provided with an inexpensive and highly efficient cooling device.

  Conventionally, in an image forming apparatus such as a laser printer, an electric latent image is formed on the surface of a photoreceptor mainly composed of amorphous selenium (Se), and then the latent image is visualized with toner by a developing device. Yes.

  Several developing rollers that rotate at high speed are provided inside the developing device in order to convey powder such as toner and carrier. When the powder is conveyed on the roller, an eddy current is generated by the magnetic field. Further, there is a problem that the heat stays in the developing device due to frictional heat of the powder and further heat generated from the motor. When this heat reaches a temperature higher than the glass transition temperature of the components contained in the toner, not only the life of the toner is shortened, but also a phenomenon called toner caking occurs, and various gears are locked to shorten the life of the motor. Cause the problem of end.

  Furthermore, since heat transfer occurs to the surface of the photosensitive member that is in contact with the developer, the surface temperature of the photosensitive member may be increased more than necessary. The softening temperature of amorphous Se is said to be around 35-40 ° C. and is slightly higher than room temperature. Therefore, when heat is input from various heat sources, it easily rises to the vicinity of the softening temperature of Se. Therefore, an increase in the surface temperature of the photoreceptor is a serious problem in a high-speed machine using a Se photoreceptor having amorphous selenium (Se) as a main component.

  On the other hand, the surface of the photosensitive member receives pressure from the developing roll of the developing machine during printing, as well as pressure from the developer of the transfer unit, the developer on the sheet, a cleaning brush (or blade), etc., so the Se softening temperature In the region, there is a problem that scratches or dents are formed on the surface of the Se photoconductor. These damages cause white spots and black spots on the printed matter, and seriously affect the print quality. For this reason, conventionally, the developing device is cooled by a cooling fan or water cooling, but the former method has the disadvantages of being noisy and inefficient, and the latter method has a problem of water leakage due to corrosion of the apparatus, There have been problems such as installation of water supply / drainage pipes, particularly water leakage treatment at the time of attachment / detachment in a user changeable developer.

Takeshi Tanaka; Journal of the Abrasive Technology Society, Volume 46 5 (2003) p234-P239 Japanese Patent No. 3244072 JP 05-33174 A

  An object of the present invention is to provide an image forming apparatus that solves the above-described conventional problems.

  Specifically, the image forming apparatus can prevent the surface temperature of the developing device and the photosensitive member from being increased to protect the photosensitive member, prevent the quality of the printed image from being deteriorated, and prevent the toner and the motor from being shortened in life. The purpose is to provide.

  It is another object of the present invention to provide an image forming apparatus having a highly efficient cooling device without causing problems such as noise and water leakage in cooling the developing device and the surface of the photosensitive member.

  In order to achieve the above object, the present invention is formed by a photoconductor, a charger that uniformly charges the surface of the photoconductor, a light source that irradiates the charged photoconductor surface with laser light, and a laser beam. An image forming apparatus having a developing unit that visualizes an electrical latent image with toner and a transfer unit that transfers a visible image to a recording medium, means for generating cold air, and passing the cold air onto the surface of the photoreceptor through a vortex tube. One feature resides in the provision of a cold air device comprising a means for spraying.

  Other features of the present invention include a photoconductor, a charger that uniformly charges the surface of the photoconductor, a light source that irradiates the charged photoconductor surface with laser light, and an electrical latent image formed by the laser light. In an image forming apparatus having a developing unit that visualizes an image with toner and a transfer unit that transfers a visible image to a recording medium, a member that contacts the surface of the photoreceptor, a means for generating cold air, and a vortex tube And means for spraying the member.

  Other features of the present invention include a photoconductor, a charger that uniformly charges the surface of the photoconductor, a light source that irradiates the charged photoconductor surface with laser light, and an electrical latent image formed by the laser light. In an image forming apparatus having a developing unit that visualizes an image with toner and a transfer unit that transfers a visible image to a recording medium, a member that contacts the recording medium, a means for generating cold air, and the cold air through a vortex tube Means for spraying the member.

  Other features of the present invention include a photoconductor, a charger that uniformly charges the surface of the photoconductor, a light source that irradiates the charged photoconductor surface with laser light, and an electrical latent image formed by the laser light. In an image forming apparatus having a developing unit that visualizes an image with toner and a transfer unit that transfers a visible image to a recording medium, a cooling fin that is in direct contact with the developer of the developing unit, means for generating cold air, and And means for cooling the cooling fin by guiding the cold air through the vortex tube to the cooling fin.

  Other features of the present invention include a photoconductor, a charger that uniformly charges the surface of the photoconductor, a light source that irradiates the charged photoconductor surface with laser light, and an electrical latent image formed by the laser light. In an image forming apparatus having a developing device for visualizing an image with toner and a transfer device for transferring a visible image to a recording medium, means for generating cold air, and means for blowing the cold air to a housing of the developing device through a vortex tube And a cold air device comprising

  Other features of the present invention include a photoconductor, a charger that uniformly charges the surface of the photoconductor, a light source that irradiates the charged photoconductor surface with laser light, and an electrical latent image formed by the laser light. In an image forming apparatus having a developing device for visualizing an image with toner and a transfer device for transferring a visible image to a recording medium, means for generating cold air, a developing roll of the developing device and / or the cold air through a vortex tube And a means for cooling the roll by guiding it to the transport roll.

  Another feature of the present invention is that in the above-mentioned imaging apparatus, a temperature sensor is disposed in the vicinity of the cooled member, and means for controlling the flow rate of the air flow passing through the vortex tube according to the detection signal of the temperature sensor. It is in having established.

  According to the present invention, cool air is generated, and the cool air is guided to a desired location by a vortex tube to cool the photosensitive member and the developing device, so that the cooling efficiency is high and the configuration is simple, so the cost is greatly reduced. There is an effect that can be done.

  In addition, since a member required for cooling can be easily attached and detached, there is an advantage that it can be easily applied to a user changeable type developing device.

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an embodiment of an electrophotographic image forming apparatus according to the present invention. A charging device 7, a light source 8, a developing device 9, a transfer device 10 and the like are arranged in the vicinity of the rotating Se photoconductor 4. The surface of the photosensitive member 4 is charged to about 700 V by the charger 7, and then the surface of the photosensitive member is irradiated with laser light from the laser light source 8, thereby forming an electrical latent image corresponding to the image. Furthermore, the electric latent image on the surface of the photoconductor 4 is visualized with toner by the developing device 9, and then the toner image on the surface of the photoconductor 4 is transferred to the paper 11 by the transfer device 10. The toner remaining on the surface of the photoreceptor 4 is removed by the cleaning brush 13.

  In the series of steps, the surface of the photoconductor 4 receives pressure from the developing device 9, the transfer device 10, and the cleaning brush 13, and the toner 12 is pressed against the surface of the photoconductor 4.

  On the other hand, since the inside of the laser printer housing is hermetically sealed, the heat from the heat source such as a transfer device or a developing device sometimes causes the temperature to exceed 40 ° C. In the case of double-sided printing, the high-temperature paper that has passed through the fixing unit comes into contact with the surface of the photoreceptor at the transfer unit during the backside printing after the front side printing. As described above, it is inevitable that the temperature of the surface of the photoreceptor 4 rises due to various factors.

  Therefore, the present inventor examined the influence of the temperature increase of the selenium (Se) photoreceptor 4 on the image quality. For this purpose, an experiment was conducted on the change in the hardness of the Se photoconductor as the temperature of the photoconductor 4 increased. For the photoreceptor 4, Se was formed on an Al substrate by 60 μm by a vacuum deposition method. The hardness of the photoreceptor 4 was evaluated using a Knoop test method according to a JIS evaluation method with a load of 10 gf. The temperature of the photoreceptor was changed from 20 ° C. to 50 ° C.

  As a result, as shown in FIG. 2, it was confirmed that the hardness of the photoconductor gradually decreased from 20 ° C., rapidly decreased from 30 ° C. to 40 ° C., and then gradually decreased. When this photoconductor 4 was mounted on a laser printer and a print test was performed in an environment where the temperature was changed, the quality of the printed matter and the degree of damage to the surface of the photoconductor 4 were tested, and the results shown in Table 1 were obtained.

  From this result, it has been found that when the temperature of the photosensitive member 4 is 40 ° C. or more, printing omission occurs in the printed matter. On the other hand, Table 2 shows the results of investigating the damage state of the surface of the photoreceptor 4.

  From this result, it was found that the surface of the photoconductor 4 was indented at a temperature of 40 ° C. or higher. That is, from Tables 1 and 2, it is clear that the formation of a dent on the surface of the photoconductor 4 and the printing omission of the printed matter are closely related.

  From the above examination, in order to form a high-quality image, it is necessary to keep the temperature of the surface of the photoreceptor below 40 ° C., and more desirably, keep it at 35 ° C. or less. found.

  Based on the above findings, the present invention is characterized in that it includes a cold air device 1 for cooling the surface of the photoreceptor as described below.

  In the embodiment shown in FIG. 1, the cold air device 1 includes a vortex tube 1-1, a compressor 1-2, a manifold 1-3, and a flow meter 6. As the vortex tube 1-1, a vortex tube manufactured by Sanwa Enterprise Co. was used in this example.

  As described in Non-Patent Document 1, several cold air supply systems have been known in the past, but electrophotography is seen from the viewpoint of the temperature of the cold air, the amount of air flow, the structure of the cooling target member, the cooling temperature, and the like. It was confirmed that the method using a vortex tube is most suitable for cooling the image forming apparatus of the type.

  In this embodiment, first, air is compressed by the compressor 1-2 to produce cold air. According to experiments, it was possible to easily produce cold air of about −50 ° C. with a small compressor without using a conventional refrigerator. This cold air is supplied to the manifold 1-3 via the vortex tube 1-1. Cold air is uniformly blown from the manifold 1-3 in the width direction of the photoreceptor 4.

  On the other hand, a temperature sensor 5 is provided close to the photoconductor 4 and the surface temperature of the photoconductor 4 is measured. The measured temperature signal is supplied to a controller (not shown), and a difference from a predetermined temperature, for example, an environmental temperature is calculated. A signal corresponding to this difference is sent to the flow meter 6 to control the amount of cold air blown from the manifold 1-3 in the width direction of the photoreceptor 4.

  The controller tracks changes in the temperature of the photoconductor 4 with time, adjusts the air volume while predicting future increases, measures the ambient temperature and humidity, and prevents condensation from being generated by the cold air blown on the surface of the photoconductor 4. Adjust the temperature, humidity and flow rate of cold air.

  According to an experiment by the present inventor, the cold air device 1 is mounted on a laser printer, the laser printer is placed in a temperature-controlled room adjusted to 45 ° C., and the surface temperature of the photoconductor 4 is set to 35 ° C. As a result of performing a printing test and evaluating the quality of the printed matter and the degree of damage on the surface of the photosensitive member 4, it was confirmed that the printed matter was free of defects and the surface of the photosensitive member 4 was not damaged such as a depression. .

  FIG. 3 is a schematic configuration diagram showing a second embodiment of the image forming apparatus according to the present invention. In the figure, the same components as those in FIG.

  In the first embodiment, the cold air formed by the cold air device 1 is blown in the width direction of the photoconductor 4, but in this embodiment, a roll 1-4 that contacts the photoconductor 4 is provided, and the vortex tube 1-1. It was comprised so that the cold wind supplied from may be sprayed on the roll 1-4. Even if the roll 1-4 is cooled in this way and the cooled roll 1-4 is brought into contact with the photoreceptor 4 to remove heat, the same effect as in the first embodiment can be obtained.

  According to the present embodiment, since the flow of the cold air can be controlled by the pipe to which the cooling object is attached, it is necessary to consider the treatment of the air warmed by the operation of the laser printer without scattering the toner and paper dust. There is no advantage.

  In the above-described embodiment, the rolls 1-4 are cooled. However, other members that contact the photoconductor 4, such as a fur brush or a blade-like member, may be cooled.

  FIG. 4 is a schematic configuration diagram showing a third embodiment of the image forming apparatus according to the present invention. In the figure, the same components as those in FIG.

  In this embodiment, a cooling roll 1-5 that is in contact with the paper 11 conveyed to the transfer device 10 is provided. The cold air from the vortex tube 1-1 is blown to the cooling roll 1-5 through the flow meter 6. On the other hand, temperature sensors 5-1 and 5-2 are provided in the conveyance path of the paper 11, and the temperature of the paper 11 before and after the cooling roll 1-5 is measured. Added to the bowl. The controller cools the cooling roll 1-5 so that the temperature of the photoconductor 4 becomes an optimum value while monitoring the temperature of the paper 11 before and after cooling.

  In addition to the cooling roll 1-5, the fur brush or blade-like member may be cooled and brought into contact with the paper 11. It is also possible to cool the sheet 11 by bringing the cooling body into contact with only the front surface or the back surface.

  FIG. 5 is a schematic diagram showing a fourth embodiment of the image forming apparatus according to the present invention. In the figure, the same components as those in FIG.

  In this embodiment, the developing device 9 is cooled by blowing cold air from the vortex tube 1-1 to the developing device 9.

  FIG. 6 shows an enlarged view of the developing device 9. The toner 9-4 loaded in the toner hopper 9-3 is mixed with a carrier (not shown) and conveyed to the developing roller 9-6 by the conveying roller 9-7. The toner and the carrier are collectively referred to as a developer. The developer is transported to the surface of the photoconductor 4 in a thin layer with a transport amount limited by a doctor blade (not shown). The developer is skillfully transported by a magnetic field formed by a magnet (not shown) set in the roll. At this time, since a carrier having magnetism as a developer component passes through a magnetic field rotating at a high speed, an eddy current is generated, and the developer generates heat due to the eddy current. Therefore, although the cooling fin 9-5 is attached as a heat dissipation measure, it is difficult to say that sufficient heat removal has been achieved, and heat is conducted to the photoconductor 4, and sometimes the life of the photoconductor 4 is shortened.

  Accordingly, in this embodiment, as shown in FIG. 7, in order to efficiently remove the heat of the developer, cooling fins 9-8 and 9-9 that are in direct contact with the developer are disposed, and cold air is supplied to the fins. The inlets 9-10 and 9-11 are provided, and the cold air from the cold air device 1 is guided to the cold air inlets 9-10 and 9-11 via a quick coupling (not shown) so that the cold air flows.

  Further, a temperature signal measured by a temperature sensor 5-4 attached in the vicinity of the developing device is sent to a controller (not shown), and a necessary amount of cold air calculated from the difference from the environmental temperature is passed through the flow meter 6. Cool air is sent from the manifold 1-1 to cool the developer to a predetermined temperature. The controller tracks changes in the developer temperature with time, adjusts the air volume while predicting future increases, and measures the ambient temperature and humidity to prevent the developer from condensing. Further, the temperature, humidity, and flow rate of the cold air were adjusted so that the surface of the Se photoconductor 4 was not condensed due to excessive cooling of the developing device. In this way, the temperature inside the developing device 9, more specifically, the temperature of the developer could be controlled. In this embodiment, it was confirmed that the developing device temperature, which has been conventionally raised to 40 ° C., can be lowered to the ambient environmental temperature of 20 ° C.

  FIG. 8 shows another embodiment of the developing unit 9, and boxes 9-12 and 9-13 for cooling by circulating cold air are provided at the positions of the conventional cooling fins to cool the housing of the developing unit 9. It is what I did. Even with an extremely simple configuration as in the present embodiment, the same effects as in the previous embodiment were obtained.

  FIG. 9 is a schematic diagram showing the fifth embodiment of the image forming apparatus according to the present invention. In the figure, the same components as those in FIG.

  In this embodiment, the cool air from the vortex tube 1-1 is guided to the cool air outlet 9-14, and is directly blown from the outlet 9-14 to the housing of the developing device 9. Even with an extremely simple configuration as in the present embodiment, the same effects as in the previous embodiment were obtained.

  FIG. 10 shows another embodiment of the developing device 9, in which cold air supply ports 9-15 and 9-16 are provided at the central portions of the developing roll 9-6 and the conveying roll 9-7. The cool air from the vortex tube 1-1 was guided to the cool air supply ports 9-15 and 9-16 through a coupling (not shown) so that the cool air was allowed to flow through the developing roll 9-7. It has been found that the same effect can be obtained even with such a configuration.

  As is apparent from the above description, the present invention generates cold air, guides the cold air to a desired location using a vortex tube, and cools it by blowing cold air, so there is no problem such as water leakage and the cooling effect is high. There is an advantage.

  In addition, although this invention was demonstrated by the Example, it is easy to comprise a various deformation | transformation in the range which does not change the fundamental view of this invention, and these are also contained in this invention. For example, it can also be set as the structure which cools together using 2 or more of the Example shown in FIGS.

1 is a schematic configuration diagram illustrating a first embodiment of an image forming apparatus according to the present invention. It is a figure which shows the relationship of the hardness with respect to the temperature change of a photoreceptor. It is a schematic block diagram which shows the 2nd Example of the image forming apparatus which concerns on this invention. It is a schematic block diagram which shows the 3rd Example of the image forming apparatus which concerns on this invention. It is a schematic block diagram which shows the 4th Example of the image forming apparatus which concerns on this invention. It is a schematic block diagram of the conventional developing device. It is a schematic block diagram which shows the Example of the developing device in this invention apparatus. It is a schematic block diagram which shows another Example of the developing device in this invention apparatus. It is a schematic block diagram which shows the 5th Example of the image forming apparatus which concerns on this invention. It is a schematic block diagram which shows another Example of the developing device in this invention apparatus.

Explanation of symbols

1: Cold air device 1-1: Vortex tube 1-2: Compressor 1-3: Manifold 1-4: Roll 1-5: Cooling roll 4: Photoreceptor 5: Temperature sensor 5-1: Paper temperature sensor 5-2 : Temperature sensor for paper 5-3: developing device temperature sensor 6: flow meter 7: charger 8: light source 9: developing device 9-3: toner hopper 9-4: toner 9-5: cooling fin 9-6: developing roll 9-7: Conveying roll 9-8: Return developer cooling fin 9-9: Return developer cooling fin 9-10: Cold air inlet 9-11: Cold air inlet 9-12: Cooling box 9-13: Cooling box 9-14: Cold air outlet 9-15: Cold air supply port 9-16: Cold air supply port 10: Transfer device 11: Paper 12: Toner 13: Fur brush

Claims (7)

  A photoreceptor, a charger that uniformly charges the surface of the photoreceptor, a light source that irradiates the charged photoreceptor surface with laser light, and a developer that visualizes an electrical latent image formed by the laser light with toner And a transfer device for transferring a visible image to a recording medium, comprising: a cool air device comprising: a means for generating cold air; and a means for blowing the cold air onto the surface of the photoreceptor through a vortex tube. An image forming apparatus.   A photoreceptor, a charger that uniformly charges the surface of the photoreceptor, a light source that irradiates the charged photoreceptor surface with laser light, and a developer that visualizes an electrical latent image formed by the laser light with toner And a transfer device that transfers a visible image to a recording medium, a member that contacts the surface of the photoconductor, a means for generating cold air, and a means for blowing the cold air onto the member through a vortex tube. An image forming apparatus comprising the image forming apparatus.   A photoreceptor, a charger that uniformly charges the surface of the photoreceptor, a light source that irradiates the charged photoreceptor surface with laser light, and a developer that visualizes an electrical latent image formed by the laser light with toner And a transfer device for transferring a visible image to a recording medium, comprising: a member in contact with the recording medium; means for generating cold air; and means for blowing the cold air onto the member through a vortex tube. An image forming apparatus.   A photoreceptor, a charger that uniformly charges the surface of the photoreceptor, a light source that irradiates the charged photoreceptor surface with laser light, and a developer that visualizes an electrical latent image formed by the laser light with toner And an image forming apparatus having a transfer device for transferring a visible image to a recording medium, a cooling fin that is in direct contact with the developer of the developing device, a means for generating cold air, and the cooling fin through the vortex tube. An image forming apparatus comprising: means for cooling the cooling fins.   A photoreceptor, a charger that uniformly charges the surface of the photoreceptor, a light source that irradiates the charged photoreceptor surface with laser light, and a developer that visualizes an electrical latent image formed by the laser light with toner And a transfer device for transferring a visible image to a recording medium, comprising: a cool air device comprising: means for generating cold air; and means for blowing the cold air through a vortex tube to the housing of the developing device. An image forming apparatus.   A photoreceptor, a charger that uniformly charges the surface of the photoreceptor, a light source that irradiates the charged photoreceptor surface with laser light, and a developer that visualizes an electrical latent image formed by the laser light with toner And a transfer device for transferring a visible image to a recording medium, a means for generating cold air, and the cold air is guided to a developing roll and / or a transport roll of the developing device through a vortex tube. An image forming apparatus comprising: a cooling unit. 7. A device according to claim 1, wherein a temperature sensor is disposed in the vicinity of the cooled member and the flow rate of the air flow passing through the vortex tube is controlled in accordance with a detection signal of the temperature sensor. An image forming apparatus provided.

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