JP4775014B2 - Image forming apparatus - Google Patents

Description

  The present invention is a belt having a laminated structure of a resistance layer and a dielectric layer and capable of generating an electrostatic adsorption force, and having a scale pattern formed along the longitudinal direction thereof, and a belt with a scale pattern using the same The present invention relates to a conveyance device and an image forming apparatus.

  In general, a fixed head type ink jet printer is provided with an ink jet head having a number of nozzles in a direction parallel to the recording paper width over the recording paper width, and the recording paper is relatively moved in a direction orthogonal to the recording paper width. In this case, the ink droplets are ejected from the nozzles to form an image on the recording paper for printing. Then, in order to move the recording paper relatively, by using a conveyance belt in which a charged region is formed, by using the electrostatic adsorption force, the recording paper is conveyed while being securely held without being lifted from the conveyance belt, High-speed printing is performed.

  By the way, the landing position of the ink droplets on the recording paper is affected by the fluctuation of the recording paper feeding speed. To improve the accuracy of the landing position, a fixed interval according to the recording paper feeding speed is required. It is necessary to eject ink droplets. For this reason, a scale film with a scale pattern is attached to one end of the conveyor belt, the scale pattern is detected by an optical sensor, and the change in light transmittance is detected as an analog electrical signal. By generating a pulse signal and determining the ejection timing of the ink droplets from the inkjet head using this pulse signal, the ink droplets are ejected in accordance with the paper feed speed of the recording paper held on the conveyance belt. Yes.

  The scale film is configured by, for example, forming a light-shielding scale pattern on a translucent resin film, and as shown in FIG. The scale film 101 is integrally provided with the conveying belt 102 by bonding or heat welding at the position.

  However, when the scale film 101 is attached to the front or back surface of the conveyor belt 102, the scale film 101 generally has the same thickness as the conveyor belt 102 in order to ensure the same durability as the conveyor belt 102. Yes. When the conveyor belt 102 passes through the wrapping portion of the roller that supports the conveyor belt 102 (FIG. 5B), the surface of the conveyor belt 102 on which the scale film 101 is attached and the scale film Since a circumferential length difference occurs between the scale film 101 and the scale film 101, the scale film 101 may be wavy. Further, even when the conveyor belt 102 is left in a stationary state, the conveyor belt 102 may be curled, and in this case, the scale film 101 may be wavy. In particular, when the conveyance belt 102 and the scale film 101 are bonded via the adhesive layer 103 (FIG. 5A), the adhesive layer 103 is distorted by passing through the wound portion of the roller or leaving it in a stationary state. If it occurs, the scale film 101 may be wavy due to the distortion of the adhesive layer 103. Furthermore, when the material of the conveyance belt 102 and the material of the scale film 101 are different, there may be a difference in the circumferential length due to a difference in thermal expansion coefficient.

Such undulations of the scale film 101 cause a positional deviation between the transport belt 102 and the scale film 101, that is, the position of the recording paper P cannot be accurately detected, and the ink landing interval is reduced. Deviation is caused and the printed image is deteriorated.
In order to avoid this, for example, as described in Patent Document 1, an electrode formed in a comb shape for generating electrostatic attraction force is used as a scale pattern, and the scale pattern is formed on the transport belt itself. There has been proposed a method in which a positional deviation between the conveyor belt and the scale pattern is avoided by forming.
JP 2003-89446 A

As described above, by forming a scale pattern on the conveyance belt itself, the movement state of the conveyance belt can be detected without being affected by the positional deviation between the conveyance belt and the scale pattern.
However, as described above, when the comb-like electrode formed in a comb-teeth shape is used as a scale pattern, the comb-teeth electrode is formed at intervals of several millimeters, so that the timing is in units of several millimeters. Can not occur. On the other hand, since the ejection timing of ink droplets is in the unit of several tens of microns, it is insufficient in terms of accuracy to use the comb electrodes as a scale pattern. If comb electrodes are formed at intervals of several tens of microns, it can be used as a scale pattern. However, in this case, the electrostatic adsorption force is weakened, so the recording paper must be held securely. It becomes difficult.

In addition, the electrostatic chucking method using the comb-teeth electrode is such that the power supply brush for applying a voltage to the comb-teeth electrode is slid on the conveyor belt, and the durability of these parts becomes a problem. In the case of an ink jet printer having a head, it is a feature that a large amount of printing can be performed at a high speed. Therefore, ensuring durability is an important issue.
Accordingly, the present invention has been made paying attention to the above-mentioned conventional unsolved problems, and provides an image forming apparatus using a belt with a scale pattern capable of detecting the movement state of the belt with high accuracy. It is an object.

In order to solve the above-described problems, an image forming apparatus of the present invention detects a scale pattern formed on a conveyance belt for conveying a recording medium, and detects the scale pattern detected by the scale pattern detection unit. An image forming apparatus comprising: a recording timing determining unit that determines a recording timing of an image on a recording medium based on a scale pattern; and a recording unit that performs recording on the recording medium at a recording timing determined by the recording timing determining unit The transport belt has a laminated structure of a resistance layer and a light-transmitting dielectric layer, and the resistance layer is formed by adhering a metal film to the dielectric layer. Formed by etching an electrode region to be an electrode when forming the electrode and one side end of the electrode region of the metal film. Wherein is composed of a scale pattern, wherein the scale pattern is characterized by being formed in a pattern interval which is set based on the highest quality resolution of the recording means.
According to the above configuration, since the scale pattern is formed on a part of the resistance layer in the laminated structure of the resistance layer and the dielectric layer forming the belt with the scale pattern, the scale pattern is formed integrally with the belt with the scale pattern. Therefore, even when this scale pattern belt is stretched and supported by a roller, there is no displacement between the scale pattern belt and the scale pattern, and the movement of the scale pattern belt Can be detected with high accuracy, and the movement state of the conveyor belt, that is , the movement state of the recording medium can be detected with high accuracy, so that the recording medium can be detected based on the detection result of the scale pattern by the scale pattern detection means. The recording timing is determined, and recording on the recording medium is performed at this recording timing. By performing, it is possible to improve the image quality of the image recorded in the recording medium can be recorded on the recording medium at an appropriate timing.
The metal film may be adhered to the dielectric layer by vapor deposition.

Further, the above-described belt with a scale pattern is characterized in that a protective layer for protecting the resistance layer is formed on the surface of the resistance layer opposite to the dielectric layer.
According to the above configuration, since the protective layer for protecting the resistive layer is formed on the surface of the resistive layer opposite to the dielectric layer, the resistive layer that acts as an electrode when generating the electrostatic adsorption force The durability of can be improved.

Embodiments of the present invention will be described below.
FIG. 1 is a side view showing a schematic configuration of an ink jet printer to which the present invention is applied.
As shown in FIG. 1, the ink jet printer 1 includes a paper feeding device 2 that feeds recording paper P one by one, a recording head 3 that performs printing by an ink jet method, and a recording fed by the paper feeding device 2. A transport device 4 for transporting the paper P through the vicinity of the lower portion of the recording head 3, a paper discharge device 5 for discharging the recording paper P transported by the transport device 4, and a control device 6 for controlling these devices, It has.

  The paper feeding device 2 includes a paper feeding roller 21 that discharges the recording paper P one by one, and a gate roller 22 that performs skew correction on the recording paper P discharged by the paper feeding roller 21. The recording paper P after skew correction sent out from is delivered to the transport device 4.

  The conveying device 4 includes a driving roller 41 and a driven roller 42 arranged in parallel at a predetermined interval, and a conveying belt 43 formed of a wide belt-like endless belt stretched between the driving roller 41 and the driven roller 42. A tension roller 44 that adjusts the tension of the conveyor belt 43. The drive roller 41 is disposed on the paper discharge device 5 side, and the driven roller 42 is disposed on the paper feed device 2 side. The drive roller 41 is driven by a drive motor (not shown) so that the transport belt 43 is moved to the arrow in FIG. The recording paper P that is moved in the direction and fed onto the transport belt 43 from the paper feed device 2 is transported along with the movement of the transport belt 43 and discharged to the paper discharge device 5. Further, a support member 45 that supports the conveyance belt 43 is provided at a position of the conveyance belt 43 that faces the section on which the recording sheet P is placed, and a fixed interval is provided between the recording sheet P and the recording head 3. To maintain.

  Further, the conveying device 4 is disposed in the vicinity of the driven roller 42, the charging roller 46 and the paper pressing roller 47 disposed in contact with the outer peripheral surface of the conveying belt 43, and a high-voltage power supply 46 a connected to the charging roller 46. The recording paper P placed on the conveyor belt 43 is placed on the outer peripheral surface of the conveyor belt 43 by applying a high voltage to the conveyor belt 43 via the charging roller 46 and electrostatically charging the sheet. Transport with electrostatic attraction.

  For example, the charging to the transport belt 43 may be performed on the surface of the transport belt 43 with a center of 0 [V] so that a positive potential region and a negative potential region appear alternately in the paper transport direction. This is performed by applying a rectangular wave-like alternating voltage of “+” potential and “−” potential. As a result, an electrostatic attraction force is applied between the recording paper P and the transport belt 43 to generate an electrostatic attraction force compatible with various types of paper.

  Here, the case where the charging region having a positive potential and the charging region having a negative potential are formed in the conveyance direction of the recording paper P has been described, but the present invention is not limited to this. For example, a charging roller that applies a positive voltage and a charging roller that applies a negative voltage so that a charging area having a positive potential and a charging area having a negative potential appear in a direction perpendicular to the conveyance direction of the recording paper P. The conveyor belt 43 may be charged by being arranged so that the contact area with the conveyor belt 43 does not overlap.

As described above, when charging regions of positive and negative potential appear alternately in the recording paper conveyance direction, the conveyance belt and the charging roller deteriorate due to the discharge between the remaining potentials between the charging roller and the conveyance belt. However, it is possible to avoid the above-described deterioration by causing charging regions having positive and negative potentials to alternately appear in the direction perpendicular to the conveyance direction of the recording paper P.
The method for charging the conveyor belt 43 is not limited to this. For example, as shown in FIG. 2, as the paper pressing roller 47 in FIG. 1, a feeding roller formed of a low resistance roller and grounded to the ground. 47a may be used, and the conveying belt 43 may be DC-charged by the charging roller 46 to generate an electrostatic adsorption force on the outer peripheral surface of the conveying belt 43. Further, the electrostatic attraction force may be generated not only by the charging roller but also by a charging means using corona discharge such as corotron or scorotron. Even a simple charging means can be applied.

  A scale pattern described later is formed on the conveyor belt 43, and the scale pattern is detected by the optical sensor 8. The detection information of the optical sensor 8 is input to the control device 6, and the control device 6 recognizes the moving state of the transport belt 43 and the transport position of the recording paper P based on this information, and the gate roller 22 and the drive are driven accordingly. The rotation of the roller 41 is controlled to control the paper feed position, and after printing is started, ink droplets are ejected by the recording head 3 at a predetermined timing according to the transport position of the recording paper P. In addition, the recording paper P is intermittently fed in synchronization with the printing timing.

3A and 3B are diagrams illustrating the configuration of the conveyor belt 43, in which FIG. 3A is a top view of the conveyor belt 43, and FIG. FIG. 3C is a diagram of a scale pattern portion when the transport belt 43 is viewed from the back side, that is, the inner peripheral surface side.
As shown in FIG. 3B, the transport belt 43 is formed by a laminated structure of a resistance layer 101 and a dielectric layer 102, and the resistance layer 101 includes electrodes for forming a charged region in the dielectric layer 102. Electrode region 101a and a scale pattern 101b formed on one side end of the conveyor belt 43. In other words, a scale belt 101b is formed on a part of the resistance layer 101, and the transport belt is formed integrally with the scale pattern. Configured to be. The electrode region 101a is formed at least in a region facing a recording sheet having the maximum width that can be printed by the inkjet printer 1.

The dielectric layer 102 exhibits insulation when the voltage applied by the charging means (charging roller 46 in the case of FIG. 1) is about 2 [kV] to 5 [kV] (peak to peak). The layer 101 has a characteristic that the surface of the dielectric layer, that is, the recording paper placing surface is charged by the voltage applied by the charging means and has a volume resistance of about 10 ¹³ [Ω · cm] to 10 ¹⁹ [Ω · cm], a thickness It is formed with a layer of about 30 [μm] to 200 [μm]. The resistance layer 101 is conductive when the applied voltage of the charging means is about 2 [kV] to 5 [kV] (peak to peak), and the volume resistance is about 10 ¹² [Ω · cm] or less. Formed with.

  The pattern interval d of the scale pattern 101b is set according to the resolution of the highest image quality in the conveyance direction of the recording paper P in the inkjet printer 1. That is, when the resolution obtained with the highest image quality is 720 dpi, the scale pattern is formed with d = 70.5 [μm]. By generating digital signals at the rising and falling portions of the detected analog signal of the optical sensor 8, a timing signal of 1 pulse is generated along with the movement of the conveyance belt 43 of 35.25 [μm] corresponding to a resolution of 720 dpi. Can be generated.

  The scale pattern 101b need not be provided adjacent to the electrode region 101a as shown in FIG. In order to make the electrostatic attraction force act strongly, the electrode region 101a is formed in a portion facing the recording sheet having the maximum width among the recording sheets that can be transported, and the lateral end portion of the transport belt 43 outside thereof. The scale pattern 101b may be formed on the substrate.

  The optical sensor 8 includes a light emitting element and a light receiving element that are provided across the scale pattern 101b portion of the transport belt 43. The scale pattern is based on the light receiving state of the light receiving element that is received through the transport belt 43. In the case of using a transmissive optical sensor for detecting 1010b, a material having high resistance and light transmittance is used as the dielectric layer 102. For example, PET (polyethylene terephthalate), PC (polycarbonate), Use fluorine resin. The resistance layer 101 is made of a light-shielding and medium to low resistance material such as Al, Au, Ag, Fe, Ni, Pd, or Pt. That is, for example, the transport belt 43 is formed by the dielectric layer 102 of PET resin of about 100 [μm] and the resistance layer 101 of Al film of about 2 [μm].

  At this time, the dielectric layer 102 is formed into a belt-shaped sheet using a sheet manufacturing method such as extrusion molding. Then, an electrode region 101a of the resistance layer 101 is formed on the sheet-like dielectric layer 102 by vapor deposition, and a scale pattern is formed only on one side end of the belt-like dielectric layer 102 by photolithography / etching. 101b is formed.

Here, the case where the resistance layer 101 is adhered to the dielectric layer 102 by vapor deposition has been described. However, the present invention is not limited to this, and the resistance layer and the dielectric layer made of the metal film are bonded to the dielectric layer. A stacked structure may be formed.
In addition, as the optical sensor 8, a light emitting element and a light receiving element are provided on the outer peripheral surface or the inner peripheral surface side of the conveyor belt 43, and the reflection for detecting the scale pattern 101b based on the light receiving state of the reflected light reflected by the scale pattern 101b portion. In the case of using an optical sensor of a type, a material having light reflectivity and medium to low resistance may be used as the resistance layer 101. Specifically, Al, Au, Ag A metal such as Fe, Ni, Pd, or Pt may be used.

  Here, as described above, the transport belt 43 is formed by using the scale pattern 101 b as a part of the transport belt 43. Therefore, the scale pattern 101b is formed integrally with the conveyor belt 43 even when the conveyor belt 43 passes through the drive roller 41 or the driven roller 42 or when the conveyor belt 43 is left stationary. Therefore, there is no positional deviation between the transport belt 43 and the scale pattern 101b.

  Therefore, by detecting the movement state of the conveyance belt 43 using the scale pattern 101b, the movement state of the conveyance belt 43 can be detected without causing a positional deviation between the conveyance belt 43 and the scale pattern 101b. That is, the position of the recording paper P can be detected with high accuracy. Therefore, by determining the ejection timing of the ink droplets onto the recording paper P based on the scale pattern 101b, the ink droplets can be ejected at an appropriate timing, which is caused by the positional deviation between the transport belt 43 and the scale pattern 101b. Therefore, it is possible to suppress a decrease in print image quality and to perform high-quality recording.

Further, as described above, since the charging region is formed on the outer peripheral surface of the dielectric layer 102 by the charging roller 46, voltage is applied to the electrodes formed in a comb shape by using a sliding brush. Compared to the case, the deterioration of the durability of the charging means and the conveyor belt can be suppressed, and the durability of the conveyor can be improved.
In the above embodiment, the case where the transport belt 43 is formed by a laminated structure of the resistance layer 101 and the dielectric layer 102 has been described, but the present invention is not limited to this. As shown in FIG. 4, a resin coat layer (protective layer) 103 is formed on the side of the resistance layer 101 opposite to the dielectric layer 102, and the resin coat layer 103, the resistance layer 101, and the induced transmission 102 are laminated in this order. The conveyor belt 43 may be formed from the structure. That is, if the resistance layer 101 acting as a metal electrode is exposed, its durability is lowered. Therefore, by forming the resin coating layer 103 having light transmittance and low resistance, the durability of the resistance layer 101 is reduced. Can be improved.

As the resin coat layer 103, for example, a light-transmitting resin in which light-transmitting conductive oxide fine particles are dispersed, such as an indium oxide-based material, a zinc oxide-based material, and a tin oxide-based material can be used. .
In the above-described embodiment, the case where the present invention is applied to a printer has been described. However, the present invention is not limited to this, and an image forming apparatus that performs recording using an electrostatic adsorption type conveyance belt such as a copying machine. Etc., it is also possible to apply. In addition, the present invention is not limited to the case of transporting paper, but can be applied to the case of transporting a sheet-like object. Any conveying apparatus that conveys can be applied.

In the above embodiment, the case where the scale pattern 101b is detected from the outer peripheral surface or the inner peripheral surface side of the transport belt 43 has been described. For example, as the optical sensor 8, a reflective optical sensor is used and the transport is performed. The scale pattern 101b may be detected from the side surface of the belt 43.
In the above embodiment, the optical sensor 8 corresponds to the scale pattern detection means, the control device 6 corresponds to the recording timing determination means, and the recording head 3 corresponds to the recording means.

1 is a configuration diagram illustrating a schematic configuration of an inkjet printer to which the present invention is applied. It is a schematic block diagram which shows the other example of an inkjet printer. It is a block diagram which shows the structure of a conveyance belt. It is a block diagram which shows the other structure of a conveyance belt. It is explanatory drawing for demonstrating the arrangement | positioning method of the conventional scale pattern.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Inkjet printer, 2 Paper feeder, 3 Recording head, 4 Conveyance apparatus, 6 Control apparatus, 8 Optical sensor, 41 Driving roller, 42 Driven roller, 43 Conveyance belt, 46 Charging roller, 101 Resistance layer, 101a Electrode area, 101b Scale pattern, 102 dielectric layer

Claims (3)

Scale pattern detection means for detecting a scale pattern formed on a conveyance belt for conveying the recording medium, and recording for determining recording timing of an image on the recording medium based on the scale pattern detected by the scale pattern detection means An image forming apparatus comprising: a timing determining unit; and a recording unit that performs recording on the recording medium at a recording timing determined by the recording timing determining unit,
The transport belt has a laminated structure of a resistance layer and a dielectric layer having optical transparency ,
The resistive layer, and the electrode to become electrode region for forming the charge region formed by bonding a metal film for the dielectric layer, one lateral end portion of the electrode regions of the metal layer Composed of the scale pattern formed by etching ,
2. The image forming apparatus according to claim 1, wherein the scale pattern is formed at a pattern interval set based on a resolution of the highest image quality of the recording unit. The image forming apparatus according to claim 1, wherein the metal film is bonded to the dielectric layer by vapor deposition. The image forming apparatus according to claim 1, wherein a protective layer for protecting the resistive layer is formed on a surface of the resistive layer opposite to the dielectric layer.

Images