Patent Application
20210216027
This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2020-003007 filed Jan. 10, 2020.
The present disclosure relates to a static elimination device that eliminates static from a medium, and a medium processing device using the static elimination device.
The devices described in the patent documents below, for example, are already conventionally known as static elimination devices of this kind.
Japanese Unexamined Patent Application Publication No. 2016-157011 discloses an image forming system having, in order to suppress mediums sticking to each other: a charge control unit that charges a medium on which an image has been formed by an image forming unit; and an applied current controller that controls the current supplied to the charge control unit, on the basis of the temperature of the medium.
U.S. Pat. No. 8,320,817 B2 discloses a static elimination device that eliminates static from the front surface of a charged sheet using a contact-type static eliminator, and eliminates static from the rear surface of the charged sheet using a non-contact-type static eliminator.
Japanese Unexamined Patent Application Publication No. 2017-111329 discloses an image forming system including: a static elimination member that eliminates static from a medium; a voltage application unit that applies a static elimination voltage to the static elimination member so that a static elimination current for eliminating static from the medium flows to the medium; and a controller that, when the static elimination voltage is applied to the static elimination member, changes the transport speed of the medium, and also changes the static elimination voltage according to the change in the transport speed to thereby change the static elimination current flowing to the medium.
Japanese Patent No. 6481219 discloses a static elimination device including: multiple first discharge electrodes that oppose one surface of a sheet, are arranged on a straight line that is substantially orthogonal to the direction of movement of the sheet, and apply a direct-current voltage; and multiple second discharge electrodes that oppose the first discharge electrodes with the sheet therebetween, are arranged on a straight line that is substantially orthogonal to the direction of movement of the sheet, and apply a direct-current voltage. The first and second discharge electrodes are configured such that the polarities of adjacent discharge electrodes are reverse polarities, the polarities of opposing first and second discharge electrodes are reverse polarities, and positive ions and negative ions are present in a mixed manner between adjacent discharge electrodes.
Aspects of non-limiting embodiments of the present disclosure relate to providing a static elimination device and a medium processing device using the same, which achieve optimization of a static elimination parameter of a discharge voltage that is applied to a discharge electrode and includes at least an alternating-current component, and realize static elimination in which discharge irregularities are suppressed, when static is eliminated from a medium in a non-contact state.
Aspects of certain non-limiting embodiments of the present disclosure address the above advantages and/or other advantages not described above. However, aspects of the non-limiting embodiments are not required to address the advantages described above, and aspects of the non-limiting embodiments of the present disclosure may not address advantages described above.
According to an aspect of the present disclosure, there is provided a static elimination device including: a discharge electrode that is arranged in a non-contact state with respect to a medium and eliminates static from the medium; and a power source that applies a discharge voltage including at least an alternating-current component to the discharge electrode, in which
f/v≥0.8 (expression 1)
is satisfied, where the transport speed of the medium is v (mm/sec.) and the frequency of the discharge electrode is f (Hz).
Exemplary embodiments of the present disclosure will be described in detail based on the following figures, wherein:
Overview of Exemplary Embodiments
In the drawing, the medium processing device includes: a transport unit 13 that transports a medium S; a charging unit 14 that is provided midway along the transport path of the medium S and charges the medium S; and a static elimination device 10 that is provided further downstream in the transport direction of the medium S than the charging unit 14 and eliminates static from the medium S that has been charged by the charging unit 14.
Here, the medium processing device is not restricted to an image forming device having an image forming unit, and also includes modes not having an image forming unit. Furthermore, included in the charging unit 14 is of course a transfer unit that applies a transfer voltage, and also a transport unit that charges by friction during transport of the medium S.
In the present example, as depicted in
f/v≥0.8 (expression 1)
is satisfied, where the transport speed of the medium is v (mm/sec.) and the frequency of the discharge electrode is f (Hz); and a contact-type static eliminator 12 that is provided further upstream in the transport direction of the medium S than the non-contact-type static eliminator 11, has a static elimination member 16 making contact with the medium S which is transported, and eliminates static from the medium S by applying a voltage to the static elimination member 16.
In this kind of technical component, examples of the discharge electrode 1 include a linear electrode such as a corotron or a scorotron and what is referred to as an ionizer linear electrode.
Furthermore, in a case where the transport speed v of the medium S is quick, the ion balance deteriorates if the ion generation period (ion frequency) is not shortened. In the present application, taking this into consideration, focusing on a static elimination parameter f/v that is obtained using the transport speed v of the medium S and the frequency f of the discharge voltage that includes an alternating-current component, “0.8” is set as a boundary value in accordance with an evaluation performed using a method for evaluating sticking of the medium S which is described later, and it is made possible to realize static elimination having no irregularities compared to the case where f/v<0.8.
Furthermore, in the present example, the contact-type static eliminator 12 carries out static elimination to a considerable extent, and the non-contact-type static eliminator 11 performs the action of uniformly leveling the static elimination amount.
Supposing that static elimination processing carried out by the static elimination device (the contact-type static eliminator 12 and the non-contact-type static eliminator 11) of the present example is not carried out, as depicted in
However, if static elimination processing by the static elimination device 10 (the contact-type static eliminator 12 and the non-contact-type static eliminator 11) of the present example is carried out, as depicted in
Next, a representative mode or an exemplary mode of the non-contact-type static eliminator 11 in particular of the static elimination device 10 according to the present exemplary embodiment will be described.
First, an exemplary mode of the static elimination parameter f/v is a mode in which
f/v≥1.5 (expression 2)
is satisfied. The present example is a mode in which the amount of ions supplied to the moving area per time unit of the medium S is increased by further increasing the frequency f of a static elimination bias Vd2 with respect to the transport speed v of the medium S.
Furthermore, although the aforementioned f/v is representative of a static elimination parameter, the present disclosure is not restricted thereto, and it is acceptable for a parameter that affects the static elimination action to also be added together with f/v.
Generally, a corona discharger such as a corotron is already known as a mode in which a linear electrode is used as the discharge electrode 1, but in this kind of mode the discharge electrode 1 is covered by a housing 5 having an opening 5a in a region opposing the medium S, and it is surmised that the opening width L (mm), in the transport direction of the medium S, of the opening 5a in the housing 5 affects the static elimination action.
That is, the opening width L in the housing 5 regulates the ion emission region toward the medium S, the ion emission region narrows if the opening width L is narrow, and conversely the ion emission region widens if the opening width L is wide. Consequently, it is possible to adjust the ion amount per unit length by the relationship between the ion amount and the ion emission region. Specifically, in the case where the opening width L is long, there is concern that the ion balance may deteriorate across the entire opening 5a if the ion generation period (ion frequency) is not shortened.
Taking this point into consideration, when selecting f/v*L as a static elimination parameter, it is established that a mode satisfying the expression below is desirable.
f/v*L≥30 (expression 3)
Furthermore, from the viewpoint of preventing interference between the discharge electrode 1 and the medium S, an exemplary mode is one in which the region between the discharge electrode 1 and the medium S in
Here, in a mode in which the discharge electrode 1 has one or more linear electrodes that extend in a direction intersecting the medium S, an exemplary mode of the shielding member 6 is one in which the shielding member 6 has a through-hole 6a that exposes at least any of the one or more linear electrodes in an arbitrary region in the longitudinal direction.
In particular, in a mode in which the discharge electrode 1 has multiple linear electrodes that extend in a direction intersecting the medium S, an exemplary mode is one in which the through-hole 6a in the shielding member 6 intersects the multiple linear electrodes in an oblique direction, and multiple through-holes 6a are arranged at predetermined intervals in the length direction of the linear electrodes. The present example is effective in easily constructing a mode in which at least any of the multiple linear electrodes is exposed in an arbitrary region in the longitudinal direction.
In addition, an exemplary mode of the shielding member 6 is one in which the shielding member 6 is configured of an insulating material. The present example is effective in that ions generated by the discharge electrode 1 do not leak unnecessarily at the shielding member 6 side.
Furthermore, although static elimination parameters may be used in a fixed manner, in a mode in which the transport speed v of the medium S changes, an exemplary mode is one in which there is provided a controller 7 that controls the frequency f of the discharge voltage in accordance with the transport speed v of the medium S, as depicted in
In the case where the transport speed v of the medium S is quick, it is necessary to increase the frequency f of the discharge voltage Vd(f), but in the case where the transport speed v of the medium S is slow, it is possible to decrease the frequency f of the discharge voltage Vd(f), and the generation of noise and ozone is accordingly suppressed.
Hereinafter, the present disclosure will be described in detail on the basis of exemplary embodiments depicted in the appended drawings.
In the drawing, an image forming device 20 includes, within an image forming device housing 21: image forming units 22 (specifically 22a to 22f) that form images of multiple color components (in the present exemplary embodiment, white #1, yellow, magenta, cyan, black, and white #2); a belt-like intermediate transfer body 30 that sequentially transfers (first transfer) and retains the color component images formed by the image forming units 22; a second transfer device 50 that performs a second transfer in which the color component images transferred onto the intermediate transfer body 30 are transferred to the medium S; a fixing device 70 that causes the images subjected to the second transfer to be fixed to the medium S; and a medium transport system 80 that transports the medium S to a second transfer area. In the present example, white materials having the exact same color are used for white #1 and white #2; however, it should be noted that different white materials may be used depending on whether located at a lower layer or a higher layer than the other color component images on the medium S, and it goes without saying that a material having a transparent color may be used instead of white #1 and white #2 or a material having another special color may be used, for example.
In the present exemplary embodiment, the image forming units 22 (22a to 22f) each have a drum-like photoconductor 23, and around each photoconductor 23 there is arranged: a charging device 24 such as a corotron or a transfer roller with which the photoconductor 23 is charged; an exposure device 25 such as a laser scanning device with which an electrostatic latent image is written onto the charged photoconductor 23; a developing device 26 with which the electrostatic latent image written onto the photoconductor 23 is developed using color component toners; a first transfer device 27 such as a transfer roller with which the toner images on the photoconductor 23 are transferred to the intermediate transfer body 30; and a photoconductor cleaning device 28 with which residual toner on the photoconductor 23 is removed.
Furthermore, the intermediate transfer body 30 extends across multiple stretching rollers 31 to 33 with the stretching roller 31 for example being used as a driving roller which is driven by a driving motor that is not depicted, and the intermediate transfer body 30 moves in a circulating manner due to the driving roller. In addition, an intermediate transfer body cleaning device 35 for removing residual toner on the intermediate transfer body 30 after the second transfer is provided between the stretching rollers 31 and 33.
In addition, in the second transfer device 50, a belt transfer module 51 in which a transfer transport belt 53 is stretched across multiple stretching rollers 52 (specifically 52a and 52b) is arranged so as to make contact with the surface of the intermediate transfer body 30, as depicted in
Here, the transfer transport belt 53 is a semiconductive belt having a volume resistivity of approximately 106 to 1012 Ω·cm for which a material such as chloroprene is used, one stretching roller 52a is configured as an elastic transfer roller 55, this elastic transfer roller 55 is arranged pressed against the intermediate transfer body 30 due to the second transfer area TR with the transfer transport belt 53 interposed, a stretching roller 33 of the intermediate transfer body 30 is arranged opposing the elastic transfer roller 55 as an opposing roller 56 constituting an opposing electrode, and a transport path for the medium S is formed from the location of the one stretching roller 52a to the other stretching roller 52b.
Also, in the present example, the elastic transfer roller 55 has a configuration in which an elastic layer obtained by mixing carbon black or the like with urethane foam rubber or EPDM covers the periphery of a metal shaft.
In addition, a transfer bias Vt from a transfer power source 58 is applied via a conductive power supply roller 57 to the opposing roller 56 (also used as the stretching roller 33 in the present example), and meanwhile the elastic transfer roller 55 (the one stretching roller 52a) is grounded via a metal shaft which is not depicted, and a predetermined transfer electric field is formed between the elastic transfer roller 55 and the opposing roller 56. It should be noted that the other stretching roller 52b is also grounded, and the transfer transport belt 53 is prevented from being charged. Furthermore, when consideration is given to the detachability of the medium S at the downstream end of the transfer transport belt 53, it is effective for the stretching roller 52b at the downstream side to have a smaller diameter than the stretching roller 52a at the upstream side.
The fixing device 70 has a heat fixing roller 71 that can be rotationally driven arranged in contact with the image holding surface side of the medium S, and a pressure fixing roller 72 that is arranged pressed against and opposing the heat fixing roller 71 and rotates following the heat fixing roller 71. An image held on the medium S is passed through a pressure contact region between both fixing rollers 71 and 72, and the image is fixed by using heat and pressure. It should be noted that the fixing scheme of the fixing device 70 is not restricted to the mode given in the exemplary embodiment, and it is acceptable for a non-contact fixing scheme using laser light or the like to be selected as appropriate.
In addition, the medium transport system 80 has medium supply containers 81 and 82 at multiple levels (two levels in the present example), the medium S supplied from either of the medium supply containers 81 and 82 arrives at the second transfer area TR via a horizontal transport path 84 that extends in a substantially horizontal direction from a vertical transport path 83 that extends in a substantially vertical direction, and thereafter the medium S on which a transferred image is held arrives at the fixing site according to the fixing device 70 via a transport belt 85, and is output to a medium output receiver 86 provided at a side of the image forming device housing 21.
Also, additionally, the medium transport system 80 has a branch transport path 87 capable of inverting that branches downward from a portion located downstream in the medium transport direction from the fixing device 70 of the horizontal transport path 84. The medium S is inverted due to the branch transport path 87 and via a transport path 88 once again returns to the horizontal transport path 84 from the vertical transport path 83. An image is transferred onto the rear surface of the medium S due to the second transfer area TR, and the medium S is output to the medium output receiver 86 through the fixing device 70. Furthermore, midway along the branch transport path 87, there is provided a medium inverting mechanism 89 by which the medium S having passed along the horizontal transport path 84 is inverted and output to the medium output receiver 86. The medium inverting mechanism 89 has a branch return transport path 90 that branches from midway along the branch transport path 87 and transports the inverted medium S toward the medium output receiver 86, switching gates 91 and 92 are respectively installed at a boundary section between the horizontal transport path 84 and the branch transport path 87 and a boundary section between the branch transport path 87 and the branch return transport path 90, and the medium S having passed along the horizontal transport path 84 is inverted and output to the medium output receiver 86.
Furthermore, alignment rollers 93 that align the medium S and supply the medium S to the second transfer area TR are provided in the medium transport system 80, and in addition an appropriate number of transport rollers 94 are provided on the transport paths 83, 84, 87, and 88. Moreover, at the opposite side of the image forming device housing 21 to the medium output receiver 86, there is provided a manual medium supplier 95 with which the medium can be manually supplied to the horizontal transport path 84.
In the present exemplary embodiment, on the horizontal transport path 84 that leads from the fixing device 70 to the medium output receiver 86, a static elimination device 100 is provided further upstream in the transport direction of the medium S than the branch transport path 87 that leads to the medium inverting mechanism 89.
In the present example, the static elimination device 100 includes: a contact-type static eliminator 101 that comes into contact with the medium S and eliminates the majority of the charge that has been charged to the medium S; and a non-contact-type static eliminator 102 that is provided further downstream in the transport direction of the medium S than the contact-type static eliminator 101, and, without making contact, eliminates residual charge of the medium S that remains after static elimination has been carried out by the contact-type static eliminator 101.
Hereinafter, the contact-type static eliminator 101 and the non-contact-type static eliminator 102 will be described.
As depicted in
In addition, in the present example, a static elimination power source 115 is connected to one static elimination roller 111, a static elimination bias Vd1 (a positive direct-current voltage is used in the present example) is applied from the static elimination power source 115, and the other static elimination roller 112 is grounded.
It should be noted that it is acceptable for the static elimination power source 115 to be installed at either the front-surface side or the rear-surface side of the medium S, and in a mode where installed at the rear-surface side of the medium S, it is sufficient to use the opposite polarity to the static elimination bias or the static elimination current used in a mode where installed at the front-surface side of the medium S.
In particular, as a mode that is different from the present example, the contact-type static eliminator 101 may be provided with a contact/separation mechanism 116 that causes one static elimination roller 111 to come into contact with or to separate from the other static elimination roller 112, as depicted in
In the present example, as depicted in
A mode in which only one discharge wire 122 is used is adopted in the present example, but it should be noted that the present disclosure is not restricted thereto, and multiple discharge wires 122 may be used. Furthermore, a so-called corotron scheme is adopted in the present example, but the present disclosure is not restricted thereto, and it goes without saying that a mode may be adopted in which a grid plate serving as a control electrode is added at a location facing the opening in the static elimination housing 121 (a so-called scorotron scheme). Alternatively, a mode may be adopted in which a needle-like electrode described later is provided instead of the discharge wire 122. Furthermore, it is acceptable for the static elimination power source 125 to be installed at either the front-surface side or the rear-surface side of the medium S, and the static elimination power source 125 may be installed at both sides.
Here, the static elimination characteristics of the static eliminators 101 and 102 will be briefly described.
Here, it is assumed that the medium S has a high resistance (dielectric) similar to a resin film, and, for example, a medium S passing through the second transfer device 50 receives a transfer electric field and is charged. At such time, as depicted in
In this state, in the contact-type static eliminator 101, the static elimination bias Vd1 is applied to one static elimination roller 111, and thus a corona discharge occurs before and after a contact region (nip region) CN between the one static elimination roller 111 and the other static elimination roller 112, as depicted in
Meanwhile, regarding the static elimination characteristics of the non-contact-type static eliminator 102, as depicted in
In the present exemplary embodiment, as depicted in
In the present example, as depicted in
Here, the operation panel 140 is provided with: a start switch 141 (“switch” is written as “SW” in
Next, the image forming processing of the image forming device according to the present exemplary embodiment will be described in accordance with the flowchart depicted in
First, as depicted in
Thereafter, the medium S is transported along the horizontal transport path 84 to the second transfer area TR, and a transfer operation performed by the second transfer device 50 is carried out. Thereafter, the medium S onto which the image has been transferred passes through the fixing device 70 and the image is fixed to the medium S, and the medium S to which the image has been fixed moves toward the static elimination device 100.
In this state, the control device 131 reads physical property information of the medium S (medium type, for example) on the basis of instruction information from the physical property instruction switch 143 of the operation panel 140, for example, and determines whether or not static elimination by the static elimination device 100 is necessary. As a method for this determination, for example, it is sufficient to confirm whether or not the front surface resistance of the medium S is greater than or equal to a level requiring static elimination (1011Ω/□, for example) from the physical property information of the medium S (medium type, for example), and to determine that static elimination is required in the case of a medium S having a level that is greater than or equal to that requiring static elimination. However, it is not absolutely necessary for the front surface resistance of the medium S to be determined as internal processing, and it may be determined that static elimination is necessary from only information on the medium type.
In the present example, in the aforementioned processing to determine whether or not static elimination is required, if it is determined that static elimination is required, the medium S is transported via the static elimination processing performed by the static elimination device 100, and if it is determined that static elimination is not required, the static elimination processing performed by the static elimination device 100 is not carried out and the medium S is transported toward the medium output receiver 86.
Here, in the present exemplary embodiment, when the contact-type static eliminator 101 is in the mode depicted in
On the other hand, when the contact-type static eliminator 101 is in the mode depicted in
Next, processing in the case where static elimination is required will be described.
In the present example, the control device 131, upon determining that static elimination is required, decides a static elimination scheme and decides static elimination conditions.
In the present example, the control device 131 recognizes physical property information of the medium S (medium type, for example) on the basis of instruction information from the physical property instruction switch 143, for example, and determines whether the front surface resistance (Ω/□) of the medium S is a low resistance, an intermediate resistance, or a high resistance, as depicted in
Then, in the present example, from the viewpoint of suppressing power consumption to the minimum required, when the front surface resistance of the medium S is a low resistance, the selection switches 132 and 133 are both turned off so that neither of the contact-type static eliminator 101 and the non-contact-type static eliminator 102 is selected, and when the front surface resistance of the medium S is an intermediate resistance, the selection switch 132 is turned off and the selection switch 133 is turned on so that only the non-contact-type static eliminator 102 is selected, and furthermore when the medium S has a high resistance, both the selection switches 132 and 133 are turned on so that both the contact-type static eliminator 101 and the non-contact-type static eliminator 102 are selected.
However, from the viewpoint of increasing the accuracy of the static elimination performed by the static elimination device 100, it goes without saying that both the contact-type static eliminator 101 and the non-contact-type static eliminator 102 may be used regardless of whether the medium S has a low resistance, an intermediate resistance, or a high resistance. Furthermore, in the present example, a scheme in which only the contact-type static eliminator 101 is selected is not provided, but a scheme in which only the contact-type static eliminator 101 is selected may be provided in the case of an intermediate resistance, for example.
Furthermore, in the present example, a scheme is adopted in which the front surface resistance of the medium S is determined based on instruction information from the physical property instruction switch 143; however, the present disclosure is not restricted thereto, and the front surface resistance of the medium S may be measured and determined using a resistance measurement circuit 150 depicted in
In the present example, assuming that a medium having either a low resistance, an intermediate resistance, or a high resistance is used as the medium S for example, in the case where the medium S has a high resistance, even if the medium S is arranged extending between the measurement rollers 151 and 152 having paired structures, a measurement current from the measurement power source 153 flows across the measurement rollers 151 having a paired structure, and hardly none propagates through the medium S and reaches the ammeter 155 near the measurement rollers 152.
In contrast, in a case where the medium S has an intermediate resistance or a low resistance, these front surface resistances of the medium S are small compared to a medium S having a high resistance, and therefore, when the medium S is arranged extending between the measurement rollers 151 and 152 having paired structures, a portion of the measurement current from the measurement power source 153 flows across the measurement rollers 151 having a paired structure, the remaining measurement current propagates through the medium S and reaches the ammeter 155 near the measurement rollers 152, and the front surface resistance of the medium S is calculated according to the measurement current measured by the ammeter 155 and the applied voltage of the measurement power source 153.
It should be noted that, regarding this type of resistance measurement circuit 150, it goes without saying a configuration may be adopted in which, for example, an ammeter is interposed between ground and the elastic transfer roller 55 of the second transfer device 50, a transfer current is measured by this ammeter, a system resistance of the second transfer area TR is calculated from a transfer bias and the transfer current, and the front surface resistance of the medium S is computed.
Next, a method for deciding static elimination conditions in the present example will be described.
In the present example, as depicted in
Also, as a static elimination condition of the contact-type static eliminator 101, it is sufficient for the static elimination bias Vd1 to be decided such that a front surface potential Vc of the medium S that has been predicted or measured is reduced by the majority thereof in terms of absolute value (in the present example, the target front surface potential is Vc1). In addition, as a static elimination condition of the non-contact-type static eliminator 102, it is sufficient for the static elimination bias Vd2 to be decided depending on the static elimination condition of the contact-type static eliminator 101 (the target front surface potential Vc1 of the medium S), and for the front surface potential of the medium S to become Vc2 (substantially 0 in the present example).
It should be noted that, in the present example, a scheme is adopted in which the static elimination condition of the non-contact-type static eliminator 102 is dependent on the static elimination condition of the contact-type static eliminator 101; however, the present disclosure is not restricted thereto, and it goes without saying that a scheme may be adopted in which, for example, the static elimination condition of the non-contact-type static eliminator 102 is decided in advance, and the static elimination condition of the contact-type static eliminator 101 is made to be dependent on the static elimination condition of the non-contact-type static eliminator 102.
In this way, once the static elimination scheme and the static elimination conditions have been decided, appropriate static elimination processing is carried out according to the front surface resistance of the medium S.
For example, in a case where the medium S has a high resistance similar to a resin film, for the static elimination scheme, the contact-type static eliminator 101 and the non-contact-type static eliminator 102 are both used as depicted in
In this state, as depicted in
Then, the medium S having passed through the contact-type static eliminator 101 is next subjected to static elimination processing by the non-contact-type static eliminator 102, and the front surface potential of the medium S reaches Vc2 (substantially 0) from Vc1. At this stage, the front surface potential Vc2 of the medium S is subjected to static elimination in a uniform manner.
In particular, in the present example, when the static elimination power of the contact-type static eliminator 101 is increased, there is an increase in the variation in the charging potential of the medium S after static elimination processing by the contact-type static eliminator 101 has finished, and therefore it is desirable that the static elimination power of the non-contact-type static eliminator 102 be increased.
Furthermore, in a case where the medium S has an intermediate resistance, for the static elimination scheme, only the non-contact-type static eliminator 102 is used, the static elimination bias Vd2 decided as the static elimination condition is applied, and static elimination processing by the non-contact-type static eliminator 102 is carried out, as depicted in
In addition, in a case where the medium S has a low resistance, as depicted in
As depicted in
In the present example, the Asker C hardness of the elastic layer 171 is preferably greater than or equal to approximately 50 degrees and less than or equal to approximately 90 degrees in view of the static elimination characteristics, and is more preferably greater than or equal to approximately 60 degrees and less than or equal to approximately 80 degrees. Here, the Asker C hardness refers to the rebound hardness when the load is 200 g, and is measured in conformance with JIS-K7312 and JIS-S6050 using a de facto standard Asker C hardness tester for measuring the hardness of soft rubber, sponge, and so forth manufactured by Kobunshi Keiki Co., Ltd.
According to the present exemplary embodiment, the static elimination rollers 111 and 112 both have the elastic layer 171, and therefore make contact in the contact region CN in the axial direction with both surfaces of the medium S when the medium S is nipped and transported. Therefore, even if at least one of the static elimination rollers 111 and 112 is arranged at an incline with respect to the axial direction, as long as that angle of inclination is very small, the contact state with the front surface of the medium S is maintained between the static elimination rollers 111 and 112. Therefore, in spaces CNf and CNr before and after the contact region CN with the medium S between both static elimination rollers 111 and 112, a corona discharge is carried out in a stable manner between the static elimination roller 111 and the front surface of the medium S.
In addition, as depicted in
Furthermore, in the present exemplary embodiment, the static elimination rollers 111 and 112 are arranged in contact even when the medium S is not passing through; however, the present disclosure is not necessarily restricted thereto, and the static elimination rollers 111 and 112 may be arranged in a non-contact manner when the medium S is not passing through, as depicted in
In the present example, the contact pressure Fd with respect to the medium S brought about by the static elimination rollers 111 and 112 is selected to be lower than the contact pressure in the second transfer area TR of the second transfer device 50. Therefore, when the medium S passes through the contact-type static eliminator 101, there is no risk of the image formed on the medium S being unnecessarily damaged, and the transportability and static elimination operability with respect to the medium S are satisfactorily maintained.
Furthermore, the volume resistivity of the elastic layer 171 is preferably greater than or equal to approximately 104 Ω·cm and less than or equal to approximately 1010 Ω·cm, more preferably greater than or equal to approximately 103 Ω·cm and less than or equal to approximately 109 Ω·cm, even more preferably greater than or equal to approximately 106 Ω·cm and less than or equal to approximately 108 Ω·cm, and most preferably remains within this range even if there is an environmental change.
Here, it is acceptable for the method for measuring the volume resistivity to be selected as appropriate, and an example thereof is depicted in
In the drawing, a conductive roller which is either of the static elimination rollers 111 and 112 is placed on a metal plate 180, and, in a state where a predetermined load (500 g, for example) is applied in the locations of arrows A1 and A2 at both ends of the metal shaft 170 that is a core bar of the conductive roller, and in an environment having a temperature of 22° C. and a humidity of 55 RH %, a predetermined applied voltage (1000 V, for example) is applied between the metal shaft 170 which is a core bar and the metal plate 180, the current value I(A) after 10 seconds is read by a current measuring instrument 181, and a volume resistance R(Ω) is calculated according to the expression “R=V/I”. This measurement and calculation are carried out at four points by causing the conductive roller, which is either of the static elimination rollers 111 and 112, to rotate 90° at time in the circumferential direction, and the average value therefor is taken as the volume resistance R of the conductive roller. Then, from the volume resistance R of the conductive roller, the volume resistivity ρv(Ω·cm) of the elastic layer 171 is calculated according to the expression below.
ρv=D×W×R/t
In the expression above, D(cm) represents the axial length of the conductive roller, W(cm) represents the contact (nip) width between the conductive roller and an electrode (corresponding to the metal plate 180), and t(cm) represents the thickness of the elastic layer. Volume resistivity is calculated according to the expression above.
In the present exemplary embodiment, it is acceptable for the contact-type static eliminator 101 to use a static elimination bias Vd1 that is determined in advance; however, since physical property values and charge amounts of mediums S vary considerably, a scheme is desirable in which the static elimination bias Vd1 is controlled according to the front surface potential of the medium S.
In the present example, it is sufficient for a surface potential meter 190 to be installed in an arbitrary location between the transport rollers 94, for example, and the front surface potential of the medium S to be measured in a non-contact manner, as depicted in
In the drawing, it is checked whether or not it is a static elimination condition to use the contact-type static eliminator 101, and in the case where the contact-type static eliminator 101 is to be used, the physical property information of the medium S is read, and in addition the front surface potential of the medium S is measured by the surface potential meter 190.
It is then sufficient for the static elimination bias Vd1 to be decided and the static elimination bias Vd1 to be applied to the static elimination roller 111.
Regarding the layout of the surface potential meter 190, the surface potential meter 190 may be installed upstream or downstream in the transport direction of the medium S from the contact-type static eliminator 101. Here, in a mode in which the surface potential meter 190 is installed further upstream in the transport direction of the medium S than the contact-type static eliminator 101, it is possible to perform feedback control on the static elimination bias Vd1 of the contact-type static eliminator 101 from the first sheet of the medium S.
In contrast, in a mode in which the surface potential meter 190 is installed further downstream in the transport direction of the medium S than the contact-type static eliminator 101, after the front surface potential of the first sheet of the medium S has been measured for a test, it is possible to perform feedback control on the static elimination bias Vd1 of the contact-type static eliminator 101 for the second sheet of the medium S and thereafter. However, since the front surface potential of the medium S after static elimination by the contact-type static eliminator 101 is measured, it is not necessary for a large potential to be measured, and accordingly it is necessary for the surface potential meter 190 to be reduced in size.
It should be noted that, in the present example, the measurement result of the surface potential meter 190 is not used to control the static elimination bias Vd2 of the non-contact-type static eliminator 102. This is based on it being acceptable for the static elimination bias Vd2 of the non-contact-type static eliminator 102 to intentionally not be controlled since the static elimination potential level brought about by the non-contact-type static eliminator 102 is small compared to the static elimination potential level brought about by the contact-type static eliminator 101.
It is acceptable for the method for deciding the static elimination bias Vd1 implemented by the contact-type static eliminator 101 to be selected as appropriate; however, in the present example, it is desirable that the static elimination bias Vd1 be selected for charge to be eliminated from the medium S such that the distribution between positive charge and negative charge at the front surface after static elimination becomes uniform compared to before static elimination. In particular, in the present example, it is desirable that the medium S be subjected to static elimination in such a way that in the distribution of front surface charge after static elimination there is an increase in the proportion of the charge that was dominant before static elimination.
Here, as depicted in
At such time, as for the static elimination bias Vd1 of the contact-type static eliminator 101, when the front surface potential of the medium S after static elimination is taken as Vc2, it is sufficient for Vd1 to be selected such that |Vc2| attenuates to a value close to 0 and Vc2 has the same polarity as that of Vc1.
In this way, when selecting the static elimination bias Vd1, as depicted in
A reason for having selected this kind of static elimination pattern is so as to avoid Vc2 having a potential of the opposite polarity to the potential from before static elimination, rather than Vc2 being a value close to 0. There being an increase in the proportion of positive charge which is different from the negative charge that was dominant in the medium S before static elimination, for example, means that the static elimination bias Vd1 is too strong.
As previously mentioned, when controlling the static elimination bias Vd1 of the contact-type static eliminator 101, it is desirable that the initial value for the optimum static elimination bias Vd1 be selected with respect to the front surface potential of the medium S. However, to select the initial value for the static elimination bias Vd1, it is necessary to apply multiple candidate static elimination biases Vd1 to the medium S for testing a predetermined charged state, and to measure, using the surface potential meter 190, the degree of attenuation in the front surface potential of the medium S brought about by each static elimination bias Vd1.
Therefore, in the present example, as depicted in
In the present example, as depicted in the example in
A static elimination bias Vd1 (Vd1(0)) that is optimum in terms of performing static elimination with respect to the predetermined front surface potential Vol of the medium S is thereby calculated. Thus, based on the initial value of the static elimination bias Vd1, it is possible to select the static elimination bias Vd1 that is optimum in terms of performing static elimination with respect to an arbitrarily charged front surface potential Vol. However, it is not absolutely necessary to perform linear approximation from the measurement line, and any other scheme may be adopted provided that it is a scheme with which an initial value for the static elimination bias Vd1 is obtained from multiple front surface potentials remaining on the medium S after applying different static elimination biases Vd1.
In the present example, as depicted in the example in
In the present example, since the static elimination bias Vd2 including an alternating-current voltage component is applied between the discharge wire 122 and the static elimination housing 121, positive ions (+) and negative ions (−) produced by a corona discharge are generated in a mixed manner from the periphery of the discharge wire 122. In the present example, the positive ions (+) and the negative ions (−) are alternately generated in each half period of the frequency f (Hz) of the static elimination bias Vd2.
Here, examining the static elimination parameters of the non-contact-type static eliminator 102, if the frequency f of the static elimination bias Vd2 increases, it is surmised that accordingly the generation period of the positive ions (+) and the negative ions (−) becomes quicker, and the amount of ions generated increases.
Furthermore, focusing on the transport speed v of the medium S, in a case where the transport speed v of the medium S is quick, the ion balance deteriorates if the ion generation period is not shortened (increasing the ion frequency).
In the present example, taking this into consideration, focusing on a static elimination parameter f/v obtained using the frequency f of the static elimination bias Vd2 that includes an alternating-current voltage component, in accordance with an evaluation performed using a method for evaluating sticking of the medium S described later, when selecting a range for the optimum static elimination parameter f/v, it is established that a mode satisfying the expression below is desirable.
f/v≥0.8 (expression 1)
In expression 1, it is particularly desirable that the expression below be satisfied.
f/v≥1.5 (expression 2)
In addition, in the present example, an opening 128 in the static elimination housing 121 is formed having an opening width L in the transport direction of the medium S, as depicted in
Here, the opening width L of the opening 128 in the static elimination housing 121 regulates the ion emission region toward the medium S, the ion emission region narrows if the opening width L is narrow, and conversely the ion emission region widens if the opening width L is wide. Consequently, it is possible to adjust the ion amount per unit length by the relationship between the ion amount and the ion emission region. Specifically, in the case where the opening width L is long, there is concern that the ion balance may deteriorate across the entire opening 128 if the ion generation period (ion frequency) is not shortened.
In this way, it is surmised that the opening width L of the static elimination housing 121 has an effect on the static elimination action.
Taking this point into consideration, when selecting f/v*L as a static elimination parameter, it is established that a mode satisfying the expression below is desirable.
f/v*L≥30 (expression 3)
It should be noted that the reasons for adopting expressions 1 to 3 will be described in detail using example 4 described later.
Furthermore, in the present example, if the opening width L is narrow, it is apparent that there is a risk of the static elimination being insufficient if a high frequency of a predetermined level or greater is not used. It is estimated that this is because there is a reduction in the amount of ions received per unit length of the medium S that passes through the non-contact-type static eliminator 102 due to the ion emission region becoming narrow. On the other hand, due to the ion emission region being wide when the opening width L is large, there is an increase in the amount of ions received per unit length of the medium S that passes through the non-contact-type static eliminator 102. Thus, compared to the case where the opening width L is narrow, charge is sufficiently eliminated even with a lower frequency.
In the present example, the static elimination bias Vd2 applied to the discharge wire 122 is an alternating-current voltage component Vac (provided with a peak-to-peak voltage Vpp and the frequency f) superposed by a direct-current voltage component Vdc (a positive voltage is used in the present example), as depicted in
In
Here, in the present example, the direct-current voltage component Vdc is superposed on the alternating-current voltage component Vac in the static elimination bias Vd2, and therefore there is a change in which the alternating-current voltage component Vac is offset to the positive side by an amount commensurate to the direct-current voltage component Vdc, as indicated from the thicker line to the thinner line in
At such time, assuming that Vpp is ±4 kV, Vdc is +0.3 kV, the positive corona discharge starting voltage is +2 kV, and the negative corona discharge voltage is −1.7 kV, for example, the diagonal line regions in
In the present example, in the non-contact-type static eliminator 102, the earth electrode 123 serving as an opposing electrode that opposes the discharge wire 122 is provided grounded, as depicted in
In contrast, as depicted in
In the present example, as the static elimination power source 125, the static elimination bias Vd2 is an AC static elimination bias made up of an alternating-current voltage component superposed by a direct-current voltage component, and positive ions (+) and negative ions (−) are supplied in a mixed manner for static elimination to the front surface of the medium S, as depicted in
In contrast, as a static elimination power source 125′, assuming that a direct-current static elimination bias made up of only a direct-current voltage component is used for the static elimination bias Vd2, only positive ions (+) are generated in the periphery of the discharge wire 122 and the positive ions (+) eliminate negative charge e− on the front surface of the medium S, and negative ions (−) for eliminating positive charge e+ from among the front surface charge of the medium S are not generated and positive charge e+ on the medium S is not eliminated, as depicted in
In this way, in the present example, by adopting an AC static elimination bias, even if positive charge e+ and negative charge e− are present in a mixed manner in the front surface charge of the medium S, it is possible to eliminate both.
In the present example, in the non-contact-type static eliminator 102, static elimination parameters may be used in a fixed manner; however, in a mode in which the transport speed v of the medium S changes, it is desirable that the frequency f of the static elimination bias Vd2 be controlled according to the transport speed v of the medium S, as depicted in
That is, in the present example, a speed sensor 200 that detects the transport speed v of the medium S is provided midway along the transport path of the medium S, speed information from the speed sensor 200 is acquired by the control device 131, and the control device 131 controls the frequency f of the static elimination bias Vd2.
In the present example, a static elimination bias control program for the non-contact-type static eliminator 102 is installed in the control device 131, and the static elimination bias control processing depicted in
In
It is then sufficient for the frequency f of the static elimination bias Vd2 to be decided and the static elimination bias Vd2 to be applied to the discharge wire 122.
In the present example, for example, in a case where the transport speed v of the medium S is a speed v (fast) that is faster than a normal speed, it is sufficient for the frequency f to be set to f (high), and conversely in a case where the transport speed v of the medium S is a speed v (slow) that is slower than the normal speed, it is sufficient for the frequency f to be f (low), as depicted in
In the drawing, the image forming device 20 includes an image forming unit 210 that has the image forming units 22 housed therein, and a static elimination unit 220 that receives and eliminates static from the medium S that is output from an exit portion of the horizontal transport path 84 of the image forming unit 210, which is different from the image forming device according to exemplary embodiment 1. The image forming unit 210 incorporates the elements (the image forming units 22, the intermediate transfer body 30, the fixing device 70, and the medium transport system 80) other than the static elimination device 100, with the static elimination device 100 being incorporated in the static elimination unit 220.
It should be noted that constituent elements similar to those in exemplary embodiment 1 are denoted by reference numbers similar to those in exemplary embodiment 1 and detailed descriptions thereof are omitted here.
In the present example, as depicted in
In the present example, a control device 240 is also incorporated within the static elimination unit 220, the surface potential meter 190 that measures the front surface potential of the medium S is installed in the region between the transport rollers 223 and 224, for example, and the speed sensor 200 is installed in the region between the transport roller 222 and the contact-type static eliminator 101 on the horizontal transport path 221.
Furthermore, the basic configuration of the contact-type static eliminator 101 is substantially similar to that in exemplary embodiment 1, but the static elimination power source 115 is configured such that a positive direct-current power source 115a and a negative direct-current power source 115b are provided in parallel and are selectively switched by a changeover switch 250.
Also, the control device 240 is configured such that the positive direct-current power source 115a and the negative direct-current power source 115b of the static elimination power source 115 are selectively switched by the changeover switch 250, taking into consideration whether or not the medium S has been inverted by the medium inverting mechanism 89 within the image forming unit 210.
It should be noted that, substantially similar to exemplary embodiment 1, the control device 240 is configured such that static elimination bias control (control corresponding to the front surface potential of the medium S) for the contact-type static eliminator 101 and static elimination bias control for the non-contact-type static eliminator 102 are carried out.
In the present example, the static elimination device 100 is installed downstream in the transport direction of the medium S from the medium inverting mechanism 89 within the image forming unit 210, and therefore the positive direct-current power source 115a and the negative direct-current power source 115b of the static elimination power source 115 are selectively switched according to whether or not the medium S has been inverted.
For example, as depicted in
On the other hand, as depicted in
In the present example, the polarity of the static elimination power source 115 is switched according to whether the medium S has been inverted, but it should be noted that the present disclosure is not restricted thereto. For example, it is also possible for static elimination by the static elimination device 100 to not be carried out when the medium S has been inverted by the medium inverting mechanism 89. Furthermore, a configuration may be adopted in which static elimination processing by the static elimination device 100 cannot be selected on a UI (user interface) when the medium S has been inverted by the medium inverting mechanism 89.
In the drawing, in the basic configuration of the non-contact-type static eliminator 102, the interior of the static elimination housing 121 is partitioned into two chambers by a partitioning member 260, a discharge wire 122 (122a and 122b in the present example) is installed in each chamber, and the static elimination bias Vd2 including an alternating-current voltage component is applied from the static elimination power source 125 (provided with the alternating-current power source 126 and the direct-current power source 127) to each discharge wire 122.
In addition, in the present example, as depicted in
In particular, in the present example, a mode is adopted in which the two discharge wires 122 (122a and 122b) extend in the width direction intersecting the transport direction of the medium S; however, the through-holes 271 in the shielding member 270 intersect the discharge wires 122a and 122b in an oblique direction, and are arranged at predetermined intervals in the length direction of the discharge wires 122a and 122b, as depicted in
Consequently, in the present exemplary embodiment, at least one of the discharge wires 122a and 122b is exposed in an arbitrary region in the longitudinal direction. For example, in
In this way, in the present example, a mode is adopted in which at least one of the discharge wires 122a and 122b is exposed in an arbitrary region in the longitudinal direction, and there is no concern of the static elimination processing carried out between the discharge wires 122 and the medium S being interrupted midway along the discharge wires 122a and 122b.
In addition, in the present example, the shielding member 270 is configured of an insulating material, which is desirable in that ions generated by the discharge wires 122a and 122b do not leak unnecessarily at the shielding member 270 side. A resin such as a polycarbonate can be used as a material for the shielding member 270.
In the drawing, the non-contact-type static eliminator 102 uses a needle-like electrode 300 instead of the discharge wire 122 that is a linear electrode used in exemplary embodiments 1 and 2 and modified exemplary embodiment 1.
In the present example, as depicted in
It should be noted that it is acceptable for the number of needle-like electrodes 300 installed to be selected as appropriate such that it becomes possible for the static elimination operation to be performed across the entire medium S in the width direction, and, as depicted in
In example 1, the static elimination device 100 (the contact-type static eliminator 101 and the non-contact-type static eliminator 102) according to exemplary embodiment 1 is used, and the static elimination state brought about by the contact-type static eliminator 101 and the static elimination state brought about by the non-contact-type static eliminator 102 are visualized and evaluated.
In the drawing, reference number 330 indicates a toner spray chamber, and it is sufficient for grounded sheet metal 331 to be installed inside the spray chamber 330, a medium S such as a resin film to be laid on the sheet metal 331, air to be sprayed toward the toner inside a mesh container 332 installed inside the spray chamber 330, and a toner cloud state to be produced inside the spray chamber 330. With this configuration, toner in the form of a cloud is drawn to the charge on the front surface of the medium S and the toner adheres thereto, which leads to visualization.
As can be confirmed from
Test conditions are as follows:
In the constant voltage control in
In contrast, in the constant current control in
Test conditions are as follows:
In
In
Here, there being a difference in the bite amounts at the in-side and the out-side of the static elimination rollers means that static elimination rollers having a paired structure are arranged at an incline with respect to the axial direction, but since a mode is adopted in which the static elimination rollers have an elastic body, it is confirmed that the transportability, nipping, and static elimination operability with respect to the medium are within a satisfactory range.
In the drawing, five mediums S made up of resin films are stacked, the lower four films are fixed to sheet metal 401, static elimination is carried out, and the mediums S are left for 24 h, after which a jig 402 is mounted on the uppermost medium S, the degree to which the medium S sticks thereto is measured, and an evaluation is carried out based on the measurement value therefor.
Here, when looking at the relationship between frequency and tensile load, the results depicted in
When a medium sticking evaluation was carried out using medium A (OZK 100 made by Heiwa Paper Co., Ltd.) and medium B (OZK 188 made by Heiwa Paper Co., Ltd.) under the condition where static elimination was not carried out, and also under the condition where static elimination was carried out with the frequency f being changed to 100 Hz and 800 Hz, although measurement was not possible under the condition where static elimination was not carried out, when static elimination was carried out with the frequency being appropriately selected, the medium sticking evaluation was satisfactory for both mediums A and B in that the target tensile load or less was reached. It should be noted that the target for the tensile load is determined as 1.4 N because it has been confirmed that, as long as the target level or less is achieved, it is easy for a medium to be transported to a post-processing device by a general medium transport roller after the medium has been stacked on the medium output receiver 86.
According to
f/v≥0.8 (expression 1)
f/v≥1.5 (expression 2)
f/v*L≥30 (expression 3)
In either case, the charged state of the medium is visualized using the method used in example 1.
According to
In
Thereafter, when static elimination by the non-contact-type static eliminator is carried out with the electrode distance being changed, it is apparent that the static elimination effect brought about by the non-contact-type static eliminator is satisfactory as long as the electrode distance is within 3 mm. It should be noted that, in an example in which the electrode distance is 9 mm, it is apparent that the region between the discharge wire and the medium is too wide and the static elimination effect brought about by the non-contact-type static eliminator is insufficient.
The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-003007 | Jan 2020 | JP | national |
