JP2018150150A - Conveying belt, medium conveying apparatus, liquid ejecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conveying belt electrostatically absorbing and conveying a conveying object, that hardly deteriorates even by repeated electrification and destaticizing for a long period of time.SOLUTION: A conveying belt 9 that electrostatically adsorbs and conveys recording paper P according to the present invention is characterized in that a TSC spectrum Q has two or more peaks in a TSC spectrum diagram with TSC (thermal stimulation current) on the vertical axis and temperature on the horizontal axis, obtained using the conveying belt 9 as a sample by using a thermal stimulation current measuring device which measures TSC during a temperature rise.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a transport belt, a medium transport device on which the transport belt is mounted, and a liquid ejecting apparatus on which the medium transport device is mounted.

Conventionally, in an inkjet recording apparatus, ink is ejected onto a recording medium while scanning the inkjet head in the main scanning direction, and when the ink ejection operation of the inkjet head for one line is completed, the recording medium is moved in the sub-scanning direction (main scanning direction). The ink is ejected onto the recording medium while the ink jet head is again scanned in the main scanning direction. That is, in the ink jet recording apparatus, an ink ejection operation and an operation of transporting the recording medium by a predetermined amount in the sub-scanning direction are repeated to form an image on the recording medium.
For example, in the ink jet recording apparatus described in Patent Document 1, the conveyance belt is charged, the recording medium is attracted to the surface of the conveyance belt by static electricity, and the recording medium is conveyed by a predetermined amount in the sub-scanning direction.

JP 2007-307755 A

  However, the conveying belt deteriorates when charging and discharging are repeated for a long period of time, and is difficult to be charged, and it is difficult to accurately convey the recording medium.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
The transport belt according to this application example is a transport belt that electrostatically attracts and transports an object to be transported, and the transport belt includes a material having two or more peaks in a thermally stimulated current spectrum. To do.

In general, the charging of the conveyor belt is performed by accumulating charges at trap sites in the conveyor belt by applying an electric field. A trap site is a place or factor where charges are stored in a material, and is attributed to movement of a molecular segment, defect level at a crystal / amorphous interface, or the like. For example, when the trap site is a movement of a molecular segment, the molecular segment is polarized by application of an electric field to be charged. For example, when the trap site is at the defect level, the charge is trapped by trapping the charge at the defect level.
Accordingly, when the state of the trap site of the conveyor belt is examined, the ease of charging of the conveyor belt can be evaluated.

  In this application example, the state of the trap site is evaluated from the peak appearing in the thermally stimulated current (thermally stimulated current (hereinafter referred to as TSC)) spectrum of the material. For example, when one peak is observed in the TSC spectrum, the one peak corresponds to one trap site that accumulates charges.

  For example, when charging and discharging are repeated for a long time on the conveyor belt, if the molecular structure of the trap site changes (deteriorates), the trap site does not accumulate charges sufficiently. Furthermore, when the charge is accumulated at the trap site, if the voltage applied to the trap site increases, the deterioration of the trap site progresses quickly.

According to this application example, since there are two or more peaks of the TSC spectrum of the conveyor belt, the conveyor belt has two or more trap sites corresponding to these peaks. In this case, when accumulating charges at the trap site, the voltage applied to the trap site is divided at every two or more trap sites, so that the voltage applied to each trap site becomes lower, and the trap site. Compared with the case where the voltage applied to is high, the deterioration of the trap site is less likely to proceed.
That is, when charging and static elimination are repeated for a long time on the conveyor belt, the voltage applied to each trap site is low, so that the trap of the conveyor belt is compared with the case where the voltage applied to the trap site is high. The site is less likely to deteriorate and the conveyor belt is less likely to deteriorate. Therefore, even if charging and static elimination are repeated for a long period of time, the conveyor belt can stably convey the object to be conveyed for a long period of time.

[Application Example 2]
A medium conveyance device according to this application example includes the conveyance belt according to the application example described above and a charging unit that charges the conveyance belt.

  The conveyance belt described in the application example can stably convey the object to be conveyed for a long period of time even when charging and static elimination are repeated for a long period of time. The medium transport apparatus having the transport belt can stably transport the object to be transported for a long period of time, and can improve the reliability of the medium transport apparatus.

[Application Example 3]
A liquid ejecting apparatus according to this application example includes the medium conveyance device according to the application example described above and a liquid ejecting head that ejects liquid.

  Since the medium conveyance device described in the application example can stably convey an object to be conveyed for a long time and has improved reliability, the liquid ejecting apparatus including the medium conveyance device according to the application example is long. The transported object can be transported stably for a period, and the reliability of the liquid ejecting apparatus can be improved.

1 is a schematic diagram of an inkjet printer according to an embodiment. Sectional drawing of the conveyance belt which concerns on embodiment. The figure which shows the state of the TSC spectrum of the conveyance belt which concerns on embodiment. The figure which shows the state of the TSC spectrum after carrying out peak separation. The schematic diagram which represented the state of the conveyance belt with the equivalent circuit.

  Embodiments of the present invention will be described below with reference to the drawings. Such an embodiment shows one aspect of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. In each of the following drawings, the scale of each layer or each part is made different from the actual scale so that each layer or each part can be recognized on the drawing.

(Embodiment)
"Inkjet printer overview"
FIG. 1 is a schematic diagram of an ink jet printer according to an embodiment.
First, an outline of an ink jet printer 1 which is an example of a liquid ejecting apparatus will be described with reference to FIG.

  As shown in FIG. 1, the inkjet printer 1 includes a medium transport device 30, and the recording paper P, which is an example of a transported object, is transported by the medium transport device 30. The medium transport device 30 includes a feed roller 2, a transport belt 9, rollers 7 and 8, a charging unit 14, a charge eliminating unit 10, and the like. That is, the medium conveyance device 30 includes the conveyance belt 9 and the charging unit 14 that charges the conveyance belt 9.

  The feed roller 2 is arranged on the upstream side in the transport direction of the recording paper P with respect to the transport belt 9 and applies a driving force for transporting the recording paper P in the transport direction to the recording paper P. Further, on the upstream side in the transport direction with respect to the feed roller 2, a feeding unit (including a detachable paper cassette that stores the recording paper P, a feeding roller that feeds the recording paper P from the paper cassette, and the like) (Not shown) is provided. Further, on the downstream side in the transport direction with respect to the feed roller 2 (transport belt 9), a discharge unit (not shown) for discharging the recording paper P on which recording has been performed is provided.

The transport belt 9 is an endless belt for electrostatically attracting and transporting the recording paper P on the belt surface (paper placement surface 9 a), and is entrained between the driving roller 7 and the driven roller 8. The The driving roller 7 and the driven roller 8 arranged on the downstream side in the conveying direction with respect to the driving roller 7 are arranged parallel to each other at a predetermined interval in a substantially horizontal plane. Of the belt portion located between 7 and the driven roller 8, both the upper and lower portions are substantially horizontal.
In addition, when the diameters of the driving roller 7 and the driven roller 8 are different, the upper part of the conveying belt 9 may be substantially horizontal, and the lower part of the conveying belt 9 does not need to be horizontal.

  The drive roller 7 is rotationally driven by a drive motor (not shown). Further, the drive of the drive motor is controlled by the control unit 11, whereby the conveyor belt 9 is driven at a predetermined timing in a predetermined direction so as to have a predetermined movement amount at a predetermined movement speed. In FIG. 1, arrows (right arrow and left arrow) indicate the moving direction of the conveyor belt 9, and curved arrows attached to the driving roller 7 and the driven roller 8 indicate the rotational directions of both rollers 7 and 8.

  A charging unit 14 is provided below the driving roller 7 that drives the conveying belt 9. The charging unit 14 includes a first charging unit 15, a second charging unit 18, and a voltage applying unit 12 that applies a voltage to the charging units 15 and 18.

  The voltage application means 12 is a power supply device configured by an AC power supply, a DC power supply, a known switching regulator, and the like, and is a power supply device that can perform rectification of alternating voltage, polarity inversion, pulse modulation, and the like. Under the control of the control unit 11, the voltage application unit 12 applies a predetermined alternating voltage to the first charging unit 15 and the second charging unit 18 to charge the transport belt 9.

On the other hand, a neutralizing means 10 is provided below the driven roller 8. The neutralizing unit 10 is for eliminating the charged state of the conveyor belt 9, and is located upstream of the charging unit 14 in the moving direction of the conveyor belt 9 (in the direction of the arrow in the drawing). Under this control, before the charging unit 14 forms a charging pattern on the conveyor belt 9, the charged state of the conveyor belt 9 is canceled in advance. Various types of static eliminators can be used as the static eliminator 10 such as a known ion-type static eliminator or a self-discharge type static eliminator represented by a static eliminator brush.
As described above, the charging and discharging of the transport belt 9 are repeated by the charging unit 14 and the discharging unit 10. The conveying belt 9 is charged by the charging unit 14, thereby electrostatically attracting the recording paper P to the paper placing surface 9 a, and moving the recording paper P in the moving direction of the conveying belt 9 (the direction of the arrow in the figure). Transport.

  Further, a cleaning roller 24 is provided so as to sandwich the recording paper P with the driven roller 8. The cleaning roller 24 is provided so as to be in contact with the transport belt 9, and removes ink droplets, foreign matters, and the like attached to the transport belt 9 by contacting the transport belt 9. The cleaning roller 24 is rotationally driven in a direction against the moving direction of the transport belt 9 by a motor (not shown), and thereby wipes the transport belt 9. In addition, not only the cleaning roller 24 but the structure which can clean the conveyance belt 9, such as a wiper, may be provided.

  Above the transport belt 9, an ink jet recording head 3 is provided so as to face the surface of the transport belt 9. The ink jet recording head 3 is an example of a “liquid ejecting head”. For example, yellow (Y), magenta (M), cyan (C) in order from the upstream side in the moving direction of the conveying belt 9, that is, the conveying direction of the recording paper P. ) And nozzles (not shown) for ejecting (ejecting) black (K) ink (liquid) of four colors. The ink jet recording head 3 has a nozzle plate 3 a in which ink ejection holes (not shown) are formed on the surface facing the conveyance belt 9. Further, the ink jet recording head 3 ejects (jets) ink from the nozzle plate 3a to the recording paper P transported by the transport belt 9 at a predetermined timing under the control of the control unit 11, respectively.

  Further, an ink tank (not shown) in which inks of Y, M, C, and K are stored in the apparatus main body (not shown) of the ink jet printer 1 is detachable from or removable from the apparatus main body. Ink is supplied from the ink tank to the inkjet recording head 3 via an ink tube (not shown).

  The ink jet recording head 3 is a long head along the width direction of the conveying belt 9 which is a direction orthogonal to the conveying direction of the recording paper P, and is the largest recording paper of the recording paper P expected to be used. This is a non-scanning head formed to a length that can cover the entire width of P. The ink jet recording head 3 is not limited to this, and may be a scanning head that discharges ink while moving in the width direction of the recording paper P, a so-called serial type recording head.

  As described above, the ink jet printer 1 includes the medium transport device 30 that transports the recording paper P and the ink jet recording head 3 that ejects ink, and ejects (injects) ink from the ink jet recording head 3 onto the recording paper P. ) And the operation of transporting the recording paper P in the transport direction by the medium transport device 30 to record (print) a desired image on the recording paper P.

"Outline of conveyor belt"
FIG. 2 is a cross-sectional view of the conveyance belt according to the present embodiment.
Next, the outline of the conveyor belt 9 will be described with reference to FIG.
As shown in FIG. 2, the transport belt 9 is composed of two layers of a base material 61 and a surface layer 62. The substrate 61 is disposed on the rollers 7 and 8 side and contacts the rollers 7 and 8. The surface layer 62 is disposed on the recording paper P side, and forms a paper placement surface 9 a that electrostatically attracts the recording paper P.
The base material 61 contains a conductive filler, and the resistance value is adjusted. Since the base material 61 contains a conductive filler, accumulation of residual charges due to continuous use during charging can be prevented, and both stable adsorbability and releasability of the recording paper P can be achieved.
Examples of the conductive filler include fillers such as carbon black, graphite, Al, Ni and copper, composite oxides such as tin oxide, zinc oxide, titanate K, tin oxide-indium oxide, and oxide Sb, and ion conductive materials. Etc. can be used. As the ion conductive material, an ammonium salt, a sulfonate, a cation, a nonion, or an anionic surfactant can be used.
In the present embodiment, the substrate 61 is made of polyimide containing carbon black.

As the surface layer 62, a fluorine-based resin can be used. Specifically, as the surface layer 62, fluorine resin, fluorine-modified urethane, silicone resin, copolymerized fluorine rubber, fluorine resin-copolymerized vinyl ether, PFA (tetrafluoroethylene perfluoroalkoxy resin), FEP (tetrafluoroethylene · Coating with powder paint such as hexafluoropropylene copolymer paint) or resin tube, PTFE (tetrafluoroethylene) paint, PTFE dispersed urethane paint, enamel, ETFE (polytetrafluoroethylene) tube, PVdF (polyvinylidene fluoride) Ride), PHV (polytetrafluorovinylidene) resin, and the like can be used.
By providing the surface layer 62, the durability and wear resistance of the conveyor belt 9 can be improved.
In the present embodiment, ETFE is used for the surface layer 62.

"TSC spectrum"
FIG. 3 is a diagram illustrating a state of a TSC spectrum of the conveyance belt according to the present embodiment. FIG. 4 is a diagram showing the state of the TSC spectrum after peak separation.
In FIG. 3, the measured value of TSC is shown on the vertical axis, and the temperature (measured temperature) is shown on the horizontal axis. FIG. 3 shows the TSC spectrum Q with the background component removed.
The TSC spectrum Q is expressed by using the transport belt 9 as a sample and the TSC measured using a thermally stimulated current measuring device as the vertical axis, and the temperature (measured temperature) as the horizontal axis, and the temperature indicating the TSC state with respect to the temperature. -Current curve.

  The TSC spectrum Q is measured as follows. First, a constant electric field (trap voltage) is applied to the sample (conveyor belt 9) for a certain period of time at a high temperature, and cooling is performed with the electric field applied, and the trapped state of charge when the electric field is applied to the sample is frozen. Let Thereafter, the trap voltage is turned off and the sample is heated at a constant rate. As the temperature rises, the charge trap is released and the current generated in the sample, that is, TSC, is measured. At this time, a collect electric field is applied to the sample.

In this embodiment, it measured on the conditions shown below using the commercially available TSC measuring apparatus (Rigaku Corporation make, type TS-FETT). First, at a trap temperature of 100 ° C., a trap voltage of 100 V is applied for 10 minutes to a circular area (area 28.27 mm ² ) of a diameter of 6 mm of a piece of the conveyor belt 9, and then to 0 ° C. with the trap voltage applied. Cooled down. Then, the collect voltage was set to -5 mV, the temperature was increased at a temperature increase rate of 5 K / min, and TSC was measured.
In addition, a baseline measurement was also performed after the TSC measurement. The baseline is a temperature-current curve obtained by measurement without applying a trap voltage in the above-described TSC measurement procedure. In this embodiment, the TSC is measured using a commercially available TSC measuring device TS-FETT. However, the TSC in the present invention is not limited to this, and the electric field and temperature applied to the sample can be controlled. Any TSC measured using an apparatus capable of measuring the generated current may be used.

As shown in FIG. 3, in the TSC spectrum Q, a positive current (TSC) flows in the region of 0 ° C. to 105 ° C., and a negative current (TSC) flows in the region of 105 ° C. to 150 ° C.
As shown in FIG. 4, in the TSC spectrum Q, there are two peaks Q1 and Q2 in which TSC flows in the positive direction in the region of 0 ° C. to 105 ° C., and TSC in the negative direction in the region of 105 ° C. to 150 ° C. There are two peaks Q3 and Q4 through which.
Here, the peaks Q1, Q2, Q3, and Q4 in the TSC spectrum Q refer to portions having a convex or concave shape in the TSC spectrum Q from which the baseline (background) is removed. In addition, since the positive / negative of TSC only represents the direction in which the current that flows when the charge is released due to the temperature rise, it does not matter in this embodiment.
In the following description, the current value at the apex of the peaks Q1, Q2, Q3, Q4 in the TSC spectrum Q after subtracting the baseline is referred to as peak current I _TSC .

Theoretically, the peak current I _TSC is expressed by the following formula (1).

ここで、Ｉ_TSCはピーク電流（ピークＱ１，Ｑ２，Ｑ３，Ｑ４の頂点におけるＴＳＣ）であり、ｎ（Ｔ₀）はトラップサイトの密度であり、νは注入電荷の脱離周波数であり、Ｅ_aはトラップサイトの活性化エネルギーであり、ｋはボルツマン定数であり、Ｔは温度であり、βは昇温速度であり、Ｔ₀は測定開始温度である。
ｎ（Ｔ₀）、ν、及びＥ_aはトラップサイトの固有因子であり、β及びＴ₀は測定因子である。トラップサイトへの電荷の注入はＥ_aを超えるエネルギーが必要である。Ｅ_aはピークＱ１，Ｑ２，Ｑ３，Ｑ４においてＴＳＣが最大となる温度（ピークＱ１，Ｑ２，Ｑ３，Ｑ４の頂点の温度）で近似できる。すなわち、Ｅ_aが小さければ、ピークＱ１，Ｑ２，Ｑ３，Ｑ４は低温側に現れるとみなすことができる。

Here, I _TSC is a peak current (TSC at the vertices of peaks Q1, Q2, Q3, and Q4), n (T ₀ ) is a density of trap sites, ν is a desorption frequency of injected charges, and E _a is the activation energy of the trap site, k is the Boltzmann constant, T is the temperature, β is the rate of temperature increase, and T ₀ is the measurement start temperature.
n (T ₀ ), ν, and E _a are intrinsic factors of the trap site, and β and T ₀ are measurement factors. Injection of charges into the trapping sites are necessary energy in excess of E _a. E _a can be approximated by the temperature at which the TSC is maximum at the peaks Q1, Q2, Q3, and Q4 (the temperature at the peak of the peaks Q1, Q2, Q3, and Q4). That is, the smaller the E _a, peak Q1, Q2, Q3, Q4 may be regarded as appearing on the low temperature side.

In the TSC spectrum Q of FIG. 3, four peaks Q1, Q2, Q3, and Q4 can be clearly recognized, but when a plurality of peaks are observed superimposed, the TSC spectrum Q is fitted by the equation (1). Each peak can be separated. Here, peak separation refers to the intrinsic factors n (T ₀ ), ν, E _{a of} each peak so that the curve obtained by superimposing the peaks represented by formula (1) matches the measured TSC spectrum Q. Is to optimize the value of.

As shown in FIG. 4, in the TSC spectrum Q, the peak Q1 is located at 51 ° C., the peak Q2 is located at 87 ° C., the peak Q3 is located at 131 ° C., and the peak Q4 is located at 147 ° C. Further, since the TSC spectrum Q of the conveyor belt 9 has four peaks Q1, Q2, Q3, and Q4, there are four trap sites T1, T2, T3, and T4 corresponding to these.
Hereinafter, the temperatures at the vertices of Q1, Q2, Q3, and Q4 are referred to as peak temperatures.

  FIG. 5 is a schematic diagram showing the state of the conveyor belt in an equivalent circuit. In FIG. 5, one trap site is represented by one RC parallel circuit, trap site T1 corresponds to RC parallel circuit W1, trap site T2 corresponds to RC parallel circuit W2, and trap site T3 corresponds to RC parallel circuit W3. The trap site T4 corresponds to the RC parallel circuit W4.

As shown in FIG. 5, the conveyor belt 9 can be represented by an equivalent circuit in which an RC parallel circuit W1, an RC parallel circuit W2, an RC parallel circuit W3, and an RC parallel circuit W4 are coupled in series. For this reason, the voltage applied at the time of charging is divided for each of the trap sites T1, T2, T3, and T4, and the trap sites T1, T2, T3 are compared with the case where there is only one trap site and no voltage is divided. , T4 voltage is lowered. When the voltage applied to the trap sites T1, T2, T3, and T4 decreases, for example, when charging and discharging are repeated for a long time on the conveyor belt 9, residual charges accumulate in the trap sites T1, T2, T3, and T4, for example. As a result, it becomes difficult for the trap sites T1, T2, T3, and T4 to be injected with deterioration.
Therefore, when charging and discharging are repeated for a long time on the transport belt 9, the trap sites T1, T2, T3, and T4 are not easily deteriorated, and the transport belt 9 is not easily deteriorated.

Furthermore, in the TSC spectrum Q, the peak temperatures of the peaks Q1, Q2, Q3, and Q4 are 51 ° C., 87 ° C., 131 ° C., and 147 ° C., respectively.
For example, trap sites with a low peak temperature are charged with a low voltage, and trap sites with a high peak temperature are charged with a high voltage. Since the peak temperature increases in the order of the trap sites T1, T2, T3, T4, the trap sites T1, T2, T3, T4 are charged at a lower voltage in the order. For example, the trap site T1 is charged at a lower voltage than the trap site T4, and tends to be fully charged earlier. For this reason, if the trap sites T1, T2, T3, and T4 are charged at a lower voltage in this order, the trap sites T1, T2, T3, and T4 tend to be fully charged.

  For example, when charging and discharging are repeated with respect to the trap site (when charging and discharging are repeated with respect to the conveyor belt 9), the trap site that is charged to full charge is the trap site that is not charged to full charge. In comparison, it is considered that residual charges are easily accumulated at the trap site, and the deterioration of the trap site proceeds faster. For this reason, in the case where the full charge tends to occur in the order of the trap sites T1, T2, T3, T4, it is considered that the deterioration tends to proceed quickly in the order of the trap sites T1, T2, T3, T4.

  In the present embodiment, since the conveyor belt 9 has four trap sites T1, T2, T3, and T4, even if one trap site (for example, trap site T1) deteriorates, another trap site (for example, trap site T1). , Trap sites T2, T3, T4) are continuously charged with a predetermined charge, so that the amount of charge charged on the conveyor belt 9 (the amount of charge charged on the trap site) does not change, and the The electrostatic adsorption capability does not deteriorate, and the conveyance belt 9 can stably adsorb the recording paper P for a long period of time.

  Therefore, the medium conveyance device 30 can convey the recording paper P stably for a long period of time, and can improve the reliability of the medium conveyance device 30. Furthermore, the ink jet printer 1 can stably repeat the operation of ejecting ink from the ink jet recording head 3 onto the recording paper P and the operation of transporting the recording paper P in the transport direction by the medium transport device 30 for a long period of time. The reliability of the inkjet printer 1 can be improved.

  Therefore, in order to suppress the deterioration of the conveyor belt 9 and increase the reliability of the medium conveyor device 30 and the inkjet printer 1, there are two or more TSC spectra in the TSC spectrum Q with TSC as the vertical axis and temperature as the horizontal axis. It is preferable that the conveyor belt 9 has a peak of.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 2 ... Feed roller, 3 ... Inkjet recording head, 7 ... Drive roller, 8 ... Driven roller, 9 ... Conveyor belt, 10 ... Static elimination means, 11 ... Control part, 12 ... Voltage application means, 14 ... Charging Means 15... First charging portion 18. Second charging portion 24. Cleaning roller 61. Base material 62.

Claims (3)

A transport belt for electrostatically attracting and transporting an object to be transported,
The conveyor belt includes a material having two or more peaks in a thermally stimulated current spectrum. A conveyor belt according to claim 1;
Charging means for charging the conveyor belt;
A medium conveying apparatus comprising: The medium carrying device according to claim 2;
A liquid ejecting head for ejecting liquid;
A liquid ejecting apparatus comprising:

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