Image forming apparatus and image forming method

Abstract

To provide an image forming apparatus having a static elimination unit that can be installed in a limited space. [Solution] An image forming apparatus having a static elimination unit for eliminating static electricity from a conveyed recording medium, wherein the static elimination unit comprises a dielectric, and a discharge electrode and an induction electrode disposed on the dielectric.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus and an image forming method.

Background Art

[0002] Conventionally, for example, an image forming apparatus using an electrophotographic method or an electrostatic recording method is known. In such an image forming apparatus, it is known that a charge removing unit for removing static electricity generated on a recording medium (for example, paper) on which an image is formed is provided. For example, Patent Document 1 discloses an image forming apparatus provided with a charge removing unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The charge removing unit of the image forming apparatus disclosed in Patent Document 1 has two opposing needle-shaped electrodes (ionizers), and the recording medium passing between the two needle-shaped electrodes is charged by corona discharge to remove the charge from the recording medium. However, such a charge removing unit requires a large installation space because it has two opposing needle-shaped electrodes.

[0005] An object of the present invention is to provide an image forming apparatus having a charge removing unit that can be installed in a limited space.

Means for Solving the Problems

[0006] The present invention relates to the following image forming apparatus and image forming method. [1] An image forming apparatus having a charge removing unit for removing charge from a conveyed recording medium, wherein the charge removing unit includes a dielectric, a discharge electrode disposed on the dielectric, and an induction electrode. [2] The image forming apparatus according to [1], further comprising a guide member for guiding the recording medium, wherein the guide member is made of a metal material. [3] The image forming apparatus according to [1] or [2], wherein the distance between the discharge surface of the static elimination unit and a virtual extension surface obtained by extending the guide surface of the guide member for guiding the recording medium is 2 mm or more in the direction perpendicular to the virtual extension surface. [4] The image forming apparatus according to any one of [1] to [3], wherein the discharge surface of the static elimination unit is arranged to directly face the recording medium being transported. [5] An image forming apparatus according to any one of [1] to [4], having two static elimination units positioned opposite each other with respect to the recording medium being transported. [6] An image forming apparatus according to any one of [1] to [5], further comprising a charge state detection means for detecting the charge state of the recording medium upstream of the static elimination unit. [7] An image forming apparatus according to any one of [1] to [6], which switches whether or not to remove static electricity by the static elimination unit based on the static charge state detected by the static charge state detection means. [8] The image forming apparatus according to any one of [1] to [7], wherein the static elimination unit is located downstream of the image forming unit for forming an image. [9] The image forming apparatus according to any one of [1] to [8], wherein the static elimination unit is located immediately before the loading unit for loading the recording medium.

[10] The image forming apparatus according to any one of [1] to [9], wherein the static elimination unit is arranged in a static elimination unit for eliminating static electricity from the recording medium. An image forming method using an image forming apparatus described in any one of the items

[11] [1] to

[10] . [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an image forming apparatus having a static elimination unit that can be installed in a limited space, and an image forming method using the image forming apparatus. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1A is a side view showing the overall configuration of an image forming apparatus according to an embodiment. Figure 1B is a perspective view of a static elimination unit having a static elimination section. [Figure 2] Figure 2A is a cross-sectional view of the static elimination section. Figure 2B is a schematic diagram of the dielectric material on which the electrodes are arranged. [Figure 3] Figure 3A is a cross-sectional view of the static elimination unit, and Figure 3B is a flowchart for detecting the charge state and controlling the operation of the static elimination unit. [Figure 4] Figure 4 is a graph showing the relationship between discharge distance and charge state. [Modes for carrying out the invention]

[0009] An image forming apparatus according to one embodiment of the present invention will be described below with reference to the attached drawings. The image formed according to the embodiment described below is illustrative, and the present invention is not limited to this embodiment.

[0010] [Overall configuration of the image forming apparatus] Figure 1A is a side view showing the overall configuration of the image forming apparatus 100. As shown in Figure 1A, the image forming apparatus 100 includes a paper feeding unit 110, an image forming unit 120, non-loading units 130A, 130B, and 130C, loading units 140A and 140B, and a static elimination unit 150.

[0011] In the image forming apparatus 100, a recording medium (e.g., paper) fed from the paper feeding unit 110 is transported to the image forming unit 120 where an image is formed to become an image-formed object (e.g., a sheet of paper with an image formed on it). The image-formed object passes through the static elimination unit 150 to have its static charge removed and is then transported sequentially to the non-loading units 130A, 130B, and 130C. These non-loading units 130A to C perform operations other than loading the image-formed object as needed.

[0012] Specifically, each of the non-loading units 130A to 130C performs the following operations as required. The non-loading unit 130A corrects the curl of the image-formed material. The non-loading unit 130B detects the position where the image of the image-formed material is formed. The non-loading unit 130C has a function of folding the image-formed material. Examples of folding include various folding methods such as three-fold, four-fold, and accordion fold.

[0013] The image-formed material that has passed through the non-loading units 130A to 130C passes through the static elimination unit 150 to be statically eliminated and is then conveyed to the loading unit 140A for loading. The loading unit 140A binds the folded image-formed material and loads the bound material. Also, the image-formed material that is not bound by the loading unit 140A passes through the loading unit 140A, is statically eliminated by the static elimination unit 150, and is then conveyed to the loading unit 140B. The unfolded image-formed material is loaded in the loading unit 140B.

[0014] The recording medium to be statically eliminated in the image forming apparatus 100 may or may not have an image formed thereon. The recording medium is not particularly limited as long as an image can be formed thereon. Examples of the recording medium include paper, film, and the like.

[0015] Hereinafter, the details of each unit included in the image forming apparatus 100 will be described. First, the details of the static elimination unit 150 will be described, and then the details of the units other than the static elimination unit 150 will be described.

[0016] (Static Elimination Unit) FIG. 1B is a perspective view of the static eliminator unit 150. As shown in FIG. 1B, the appearance of the static eliminator unit 150 is in the form of a thin plate. The static eliminator unit 150 has a static elimination section 151 that exhibits a static elimination function, as shown in FIG. 1B. The recording medium that has passed through the static elimination section 151 of the static eliminator unit 150 is statically eliminated. The static elimination section 151 is disposed at a height position corresponding to the conveyance path of the recording medium of the image forming apparatus 100 in the static eliminator unit 150. That is, the static elimination section 151 is disposed in the static eliminator unit 150 so as to be at the same height as the conveyance outlet of the unit disposed immediately before the static eliminator unit 150 and the conveyance inlet of the unit disposed immediately after the static eliminator unit 150.

[0017] FIG. 2A is a cross-sectional view taken along line A-A of the static elimination section 151 shown in FIG. 1B. Note that the recording medium S is also shown in FIG. 2A for the sake of explanation. FIG. 2B is a schematic diagram of the static elimination section 151. As shown in FIG. 2A, the static elimination section 151 has a dielectric 152 in which electrodes arranged to face each other with the recording medium S interposed therebetween are disposed. The dielectric 152 thus disposed statically eliminates the conveyed recording medium S.

[0018] As shown in FIG. 2B, the dielectric 152 has a discharge electrode 153, an induction electrode 154, power supply terminals 155 and 156, a conductor 157, and a power supply 158.

[0019] When a voltage is applied from the power supply 158, current flows through the conductor 157 and the power supply terminals 155 and 156 to the discharge electrode 153 and the induction electrode 154. When current flows through the discharge electrode 153 and the induction electrode 154, corona discharge occurs. The generated corona discharge statically eliminates the recording medium S. The static elimination section 151 having the above-described configuration is compact and easy to install even when there are restrictions on the installation space. Also, since corona discharge occurs in a limited area, safety is high.

[0020] The dielectric 152 is not particularly limited as long as the discharge electrode 153 and the induction electrode 154 can be arranged on it. The shape of the dielectric 152 can be sheet-like, film-like, or plate-like. In this embodiment, the dielectric 152 is an elongated plate-like shape. The dielectric 152 has two main surfaces perpendicular to the thickness direction of the dielectric 152, corresponding to the front and back surfaces of the dielectric 152. The discharge electrode 153, the induction electrode 154, and the power terminals 155 and 156 are arranged on one of the two main surfaces. The main surface on which these are arranged faces the recording medium S and becomes a discharge surface 159 capable of non-contact static discharge of the recording medium S. The size of the dielectric 152 can be appropriately set according to the size of the recording medium S. Specifically, the length of the dielectric 152 in the longitudinal direction is preferably about the same as or longer than the width of the recording medium S. The length of the dielectric 152 is about 250 to 350 mm, the width is about 5 to 15 mm, and the thickness is about 1 to 5 mm. More specifically, the dielectric 152 is approximately 300 mm long, 10 mm wide, and 3 mm thick. Examples of materials for the dielectric 152 include dielectric materials such as alumina, glass, and mica.

[0021] The discharge electrode 153 and the induction electrode 154 are arranged in the dielectric 152 and should be able to exert static elimination capabilities when electricity flows through them. In this embodiment, the discharge electrode 153 and the induction electrode 154 are electrically connected to a power supply 158 and exert static elimination capabilities when electricity flows through them. In this embodiment, the discharge electrode 153 and the induction electrode 154 are linear conductors and are arranged side by side on the dielectric 152 so as to face each other. The linear conductors may also have multiple fine protrusions. More specifically, in this embodiment, the induction electrodes 154 and 154 are arranged parallel to each other and extend in the longitudinal direction of the dielectric 152. The materials of the discharge electrode 153 and the induction electrode 154 should be conductive. Examples of materials include stainless steel, tungsten, conductive ceramics, etc.

[0022] The discharge electrode 153 and the induction electrode 154 are electrically connected. In this embodiment, the discharge electrode 153 and the induction electrode 154 are electrically connected via power terminals 155 and 156. Specifically, one end of the discharge electrode 153 and one end of the induction electrode 154 are connected to the power terminal 155. The other ends of the discharge electrode 153 and the induction electrode 154 are connected to the power terminal 156. Thus, the discharge electrode 153 and the induction electrode 154 are electrically connected.

[0023] The power supply 158 only needs to be able to apply voltage to the discharge electrode 153 and the induction electrode 154 and allow electricity to flow. Examples of power supplies 158 include DC power supplies and AC power supplies.

[0024] It is preferable that the discharge surface 159 is positioned to directly face the image-forming object being transported. In other words, it is preferable that there are no other materials between the discharge surface 159 and the transported recording medium S, and only air is present.

[0025] As shown in Figure 2A, the dielectric 152 on which the discharge electrode 153 and induction electrode 154 are arranged may be placed both above and below the recording medium S being transported. This allows static electricity to be removed from both above and below the recording medium S. The dielectric 152 on which the discharge electrode 153 and induction electrode 154 are arranged may be placed only above the recording medium S, or only below it.

[0026] The static elimination unit 150 having the static elimination section 151 as described above may be placed at any position in the image forming apparatus 100. Specifically, the static elimination unit 150 may be placed at any position between the units of the image forming apparatus 100. More specifically, the static elimination unit 150 may be placed between the paper feeding unit 110 and the image forming unit 120. The static elimination unit 150 may be placed between the image forming unit 120 and the non-loaded unit 130A. The static elimination unit 150 may be placed between the non-loaded unit 130A and the non-loaded unit 130B. The static elimination unit 150 may be placed between the non-loaded unit 130B and the non-loaded unit 130C. The static elimination unit 150 may be placed between the non-loaded unit 130C and the loaded unit 140A. The static elimination unit 150 may be placed between the loaded unit 140A and the loaded unit 140B.

[0027] In the example shown in Figure 1A, the static elimination unit 150 is positioned between the image forming unit 120 and the non-loaded unit 130A. Furthermore, the static elimination unit 150 is positioned between the non-loaded unit 130C and the loaded unit 140A. Additionally, the static elimination unit 150 is positioned between the loaded unit 140A and the loaded unit 140B.

[0028] The number of static elimination units 150 in the image forming apparatus 100 is not particularly limited. The image forming apparatus 100 may have static elimination units 150 between all units, or it may have static elimination units 150 between specific units.

[0029] Increasing the number of static elimination units 150 makes static elimination easier, allowing operations on the recording medium performed by each unit to proceed without hindrance. On the other hand, increasing the number of static elimination units 150 increases costs. Therefore, it is preferable to place the static elimination units 150 before units where the operation on the recording medium would be hindered if the recording medium is not statically eliminated. From this viewpoint, it is preferable to place the static elimination units 150 directly before the loading unit 140A, and more preferably directly before the loading unit 140B. In other words, if a recording medium that has not been sufficiently statically eliminated is subjected to loading operations by a loading unit, the recording medium will not be loaded neatly. Specifically, the recording media being loaded may stick together due to static electricity, or they may not be loaded neatly in a aligned manner, so it is preferable that static elimination be performed directly before the loading unit.

[0030] The static elimination unit 151 is not particularly limited as long as it is positioned in a location that can eliminate static charge from the conveyed recording medium. Preferably, the static elimination unit 151 is positioned in the conveying path of the recording medium in the image forming apparatus 100. The method of eliminating static charge from the recording medium by positioning a static elimination unit 150 having the static elimination unit 151 described above between units of the image forming apparatus 100 is one example of a method for positioning the static elimination unit 151 in the conveying path of the recording medium. The method of positioning the static elimination unit 151 in the conveying path of the recording medium is not limited to the method of positioning the static elimination unit 150. For example, the static elimination unit 151 may be positioned in the conveying path of the recording medium within each unit (paper feeding unit 110, image forming unit 120, non-loading units 130A, B, C, loading units 140A, B).

[0031] As shown in Figure 2A, the static elimination unit 151 may have a guide member 160 for guiding the recording medium S. The guide member 160 should be appropriately configured to guide the recording medium S. Preferably, the guide member 160 is made of a material with high wear resistance. The material constituting the guide member 160 may include an insulating material or a metallic material. Normally, when static elimination is performed by corona discharge using a needle-shaped electrode as described in Patent Document 1 above, if the guide member contains a metallic material, corona discharge is more likely to occur between the electrode and the metallic material. And corona discharge is less likely to occur between the electrode and the recording medium. As a result, the static elimination ability may decrease if the guide member contains a metallic material.

[0032] However, as described above, with the static elimination unit 151 having a dielectric 152 on which electrodes are arranged, corona discharge occurs in a limited area, so even if the guide member 160 contains a metallic material, the decrease in static elimination ability is suppressed. Therefore, the guide member 160 can contain a metallic material. Furthermore, since metallic materials have high wear resistance, the guide member 160 containing a metallic material becomes less prone to wear.

[0033] The configuration of the guide member 160 is not particularly limited as long as it can transport the recording medium S. The guide member 160 shown in Figure 2A is integrally configured with the dielectric support portion 161 and has the dielectric support portion 161. The guide member 160 also has a portion that gradually narrows along the transport direction of the recording medium S.

[0034] The configuration of the guide member 160 is not limited to the configuration shown in Figure 2A. The configuration of the guide member 160 may be as shown in Figure 3A. That is, the guide member 160 may be a separate component from the dielectric support. In the example shown in Figure 3A, the dielectric 152 is supported by a dielectric support separate from the guide member. Also, as shown in Figure 3A, the guide member 160 may be positioned upstream of the dielectric 152 in the transport direction of the recording medium, and further downstream of the guide member 160. The upstream guide member 160 and the downstream guide member 160 may be integrally configured. In such a case, the guide member 160 has an opening, and the discharge surface 159 of the dielectric is positioned so as to directly face the recording medium with respect to the opening.

[0035] The arrangement of the discharge surface 159 of the dielectric 152 should be adjusted appropriately so that the recording medium can be stably discharged. From the viewpoint of stably exhibiting the discharge function of the dielectric, the discharge surface 159 of the dielectric is preferably arranged as follows in relation to the guide member 160 that guides the recording medium. That is, as shown in Figures 2A and 3A, a virtual extension surface M is defined as an extension of the guide surface 162 of the guide member 160, which faces the recording medium S and is approximately parallel to the recording medium. In this case, the distance between the virtual extension surface M and the discharge surface 159 in the direction perpendicular to the virtual extension surface M (hereinafter referred to as the discharge distance) is preferably 2 mm or more. On the other hand, the larger the discharge distance, the weaker the discharge ability becomes. Therefore, the discharge distance is preferably 15 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less. Note that this preferred discharge distance applies to both the discharge surface 159 arranged on the upper and lower sides of the recording medium S. Further details on this will be described later with reference to examples.

[0036] The operation of the static elimination unit 151 may be appropriately adjusted according to the charge state of the recording medium S. Figure 3B shows a flowchart when the operation of the static elimination unit 151 is appropriately adjusted according to the charge state. As shown in Figure 3B, first, printing is started (image formation is started). Next, the charge state of the recording medium that has been operated on in the image forming apparatus 100 is detected. Next, it is determined whether or not the detected charge state exceeds 100V. If it does not exceed 100V, the recording medium S is transported without operating the static elimination unit 151. On the other hand, if it exceeds 100V, the recording medium S is transported with the static elimination unit 151 operating. By switching the operation of the static elimination unit 151 on or off according to the charge state in this way, the image forming apparatus 100 can be made more energy-efficient. Note that the criteria for determining whether or not to operate is not limited to whether or not it exceeds 100V, and can be adjusted as appropriate. Specifically, the operation of the static elimination unit 151 can be performed via the control unit 10 shown in Figure 1A. The control unit 10 is, for example, a computer capable of executing programs.

[0037] The charge state can be detected using a known charge state detection means located upstream of the static elimination unit 151. Examples of charge state detection means include devices capable of measuring the potential, voltage, etc., of the recording medium. The charge state detection means may also be located immediately before the static elimination unit 151.

[0038] [Other Units] The following describes the units of the image forming apparatus 100 other than the static elimination unit 150.

[0039] (Paper feed unit) The paper feeding unit 110 supplies the recording medium to the image forming unit 120. The paper feeding unit 110 is not particularly limited as long as it can supply the recording medium. The paper feeding unit 110 is the unit located at the very top of the image forming apparatus 100.

[0040] (Image forming unit) The image forming unit 120 forms an image on the recording medium. The method by which the image forming unit 120 forms the image is not particularly limited. The image forming method of the image forming unit 120 includes electrostatic photography, electrophotography, inkjet, and the like.

[0041] (Non-loaded unit) Non-loading units 130A to C perform various operations other than loading on the image-formed recording medium (image-forming object) as needed. In the image forming apparatus 100 shown in Figure 1A, non-loading unit 130A corrects the curl of the image-forming object. Non-loading unit 130B detects the position where the image has been formed on the image-forming object. Non-loading unit 130C folds the image-forming object. Examples of folding include bi-fold, tri-fold, gatefold, etc. The folded image-forming object is bound as described later.

[0042] (Loading unit) Loading units 140A and 140B load image-forming objects. Loading unit 140A has the function of binding image-forming objects that have been folded in non-loading unit 130C by methods such as perfect binding, saddle stitching, and multi-folding. The bound image-forming objects are loaded in loading unit 140A. At this time, if the image-forming objects are statically discharged, it is easier to bind them. In particular, if the static discharge is performed by static discharge unit 150 located directly in front of loading unit 140A, it is easier to bind the image-forming objects. Loading unit 140B loads image-forming objects that have not been folded. At this time, if the image-forming objects are statically discharged, they tend to overlap neatly. In particular, if the static discharge is performed by static discharge unit 150 located directly in front of loading unit 140A, it is easier to load the image-forming objects.

[0043] (effect) According to the image forming apparatus 100 of this embodiment, the static elimination unit 151 has a dielectric 152 on which electrodes are arranged. As a result, the static elimination unit 151 is compact and easy to install in a limited space. In addition, the static elimination unit 151 discharges within a narrow range. This allows the guide member 160 for transporting the recording medium to the static elimination unit 151 to be made of a material containing metal. This also increases the durability of the guide member 160. Furthermore, because the static elimination unit 151 discharges within a narrow range, the risk of electric shock is low, making it highly safe. In addition, with the image forming method using the image forming apparatus of this embodiment, the image formed objects are statically eliminated, making it easier to stack them neatly. [Examples]

[0044] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0045] An image forming apparatus equipped with a static elimination unit was prepared, and experiments were conducted to investigate its static elimination capability. In particular, experiments were conducted to investigate the relationship between the discharge distance and the static elimination capability of the static elimination unit.

[0046] Specifically, an ion blade F2 manufactured by Fisa Corporation was used as the static elimination unit, and a static elimination unit was fabricated with the static elimination unit located above the transport path of the recording medium. The fabricated static elimination unit was placed directly in front of the loading unit 140B of the image forming apparatus to prepare the image forming apparatus. One sheet of Aurora Coat coated paper manufactured by Nippon Paper Industries was transported as the recording medium in the prepared image forming apparatus. An image was formed on the transported paper in the image forming unit, and without any operations in the non-loading unit, the paper was transported through the loading unit 140A to the loading unit 140B. At this time, the charge state of the paper in the loading unit 140B was detected using an electrostatic measuring instrument manufactured by Keyence Corporation, as a means of detecting the charge state.

[0047] Furthermore, in the paper transport process described above, the change in the charged state was measured by varying the discharge distance of the static elimination unit located above the recording medium between 0 mm and 40 mm. The measurement results are shown in the graph in Figure 4.

[0048] As can be seen from the graph in Figure 4, when the discharge distance is between 0 mm and 3 mm, the charge state changes rapidly from 2000 V to 0 V as the discharge distance increases, and the static elimination ability increases rapidly. The static elimination ability was highest when the discharge distance was 3 mm. On the other hand, as can be seen from the graph in Figure 4, when the discharge distance is between 3 mm and 40 mm, the charge state changes gradually from 0 V to 40 V as the discharge distance increases, and the static elimination ability gradually decreases.

[0049] From the graph in Figure 4, it was found that a discharge distance of 2 mm or more is preferable from the viewpoint of exhibiting stable static elimination ability. This is because the static elimination ability decreases rapidly when the discharge distance is less than 2 mm. On the other hand, when the discharge distance exceeds 3 mm, the static elimination ability gradually decreases, so from the viewpoint of exhibiting sufficient static elimination ability, it was found that a discharge distance of 15 mm or less is preferable, 10 mm or less is even preferable, and 5 mm or less is even preferable. [Industrial applicability]

[0050] The present invention can be applied, for example, to an image forming apparatus that forms images using an electrophotographic method. [Explanation of Symbols]

[0051] 10 Control Unit 100 Image forming apparatus 110 Paper feed unit 120 Image forming units 130A, 130B, 130C Non-loaded units 140A, 140B Loading Unit 150 Static Elimination Unit 151 Static Elimination Unit 152 Dielectrics 153 Discharge electrode 154 Induction electrode 155, 156 Power terminal 157 Conductor 158 Power supply 159 Discharge surface 160 Guide Member 161 Dielectric support part 162 Guide surface M Virtual extension plane S recording medium

Claims

1. An image forming apparatus having a static elimination unit for eliminating static electricity from a recording medium being transported, The static elimination unit comprises a dielectric, and a discharge electrode and an induction electrode disposed on the dielectric. Image forming apparatus.

2. The image forming apparatus according to claim 1, comprising a guide member for guiding the recording medium, wherein the guide member is made of a metal material.

3. The image forming apparatus according to claim 1, wherein the distance between the discharge surface of the static elimination unit and a virtual extension surface obtained by extending the guide surface of the guide member for guiding the recording medium, in a direction perpendicular to the virtual extension surface, is 2 mm or more.

4. The image forming apparatus according to claim 1, wherein the discharge surface of the static elimination unit is arranged to directly face the recording medium being transported.

5. The image forming apparatus according to claim 1, further comprising two static elimination units positioned opposite each other with respect to the recording medium being transported.

6. The image forming apparatus according to claim 1, further comprising a charge state detection means for detecting the charge state of the recording medium upstream of the static elimination unit.

7. The image forming apparatus according to claim 6, wherein the presence or absence of static discharge by the static discharge unit is switched based on the static charge state detected by the static charge state detection means.

8. The image forming apparatus according to claim 1, wherein the static elimination unit is located downstream of the image forming unit for forming an image.

9. The image forming apparatus according to claim 1, wherein the static elimination unit is positioned immediately before the loading unit for loading the recording medium.

10. The image forming apparatus according to claim 1, wherein the static elimination unit is arranged in a static elimination unit for eliminating static electricity from the recording medium.

11. An image forming method using an image forming apparatus according to any one of claims 1 to 10.

Images