JP2019185019A - Image forming apparatus - Google Patents

Abstract

To solve such a problem that a belt to which an ion conductive agent is added to adjust an electric resistance value has high transparency, so that when the belt is used for an image forming apparatus for detecting the reflected light of light with which the belt is irradiated and performing correction control relating to an image, it is difficult to suppress erroneous detection in the correction control.SOLUTION: Detection means 40 executes the correction control of an image forming condition on the basis of the detection results of the reflected light of a test patch transferred from a photoreceptive drum 1 to an intermediate transfer belt 10 and the reflected light when the intermediate transfer belt is irradiated with infrared light. The intermediate transfer belt 10 has a base layer 10a which is a thickest layer among a plurality of layers constituting the intermediate transfer belt 10 and to which the ion conductive agent is added and an inner surface layer 10b whose light transmittance is lower than that of the base layer 10a in the thickness direction of the intermediate transfer belt 10.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer using an electrophotographic system.

  As an electrophotographic image forming apparatus, there is known a configuration of a tandem type image forming apparatus in which a plurality of image forming units are arranged in the moving direction of a belt such as a conveyance belt or an intermediate transfer belt. Each color image forming unit has a drum-shaped photosensitive member (hereinafter referred to as a photosensitive drum) as an image carrier. The toner images of the respective colors carried on the photosensitive drums of the respective colors are transferred to a transfer material such as paper or an OHP sheet conveyed by a transfer material conveyance belt, or transferred to an intermediate transfer belt after being transferred once. Then, the toner image is fixed to a transfer material by a fixing means.

  Also, in an electrophotographic image forming apparatus, image formation such as the position and density of an image to be formed due to changes in environmental conditions in which the apparatus is placed, deterioration of photosensitive drums and toner over time, temperature changes in the apparatus, etc. Conditions may vary. Therefore, a detection toner image (hereinafter referred to as detection toner) transferred from the photosensitive drum to the belt or reflected light from the belt is detected by a detection unit such as an optical sensor, and image forming conditions are determined based on the detection result. Correction control may be performed to correct the above. More specifically, in such correction control, the position and density information of the detected toner is obtained by using the specularly reflected light from the belt and the diffusely reflected light from the detected toner, and the position and density of the image, etc. Is fed back to the correction of the image forming conditions.

  As a belt used in an image forming apparatus, an electronic conductive agent such as carbon or an ion conductive conductive agent such as an ion conductive polymer (hereinafter referred to as an ionic conductive agent) is added to a base resin as a base material of the belt. A device in which the electric resistance value is adjusted is widely known. Here, since the belt obtained by adding the ion conductive agent has high transparency, the belt transmits the light from the light source. May occur. With respect to such a problem, Patent Document 1 discloses a belt configuration that can appropriately regulate the light transmittance of the belt by adding a colorant.

JP 2002-265642 A

  However, in the configuration of Patent Document 1, since the dispersion state of the colorant affects the resistance distribution of the belt, stable transferability is ensured when the uniformity of the electric resistance value of the belt is impaired. May be difficult.

  Therefore, the present invention is to suppress erroneous detection in correction control while ensuring stable transferability in an image forming apparatus that performs correction control related to an image by detecting reflected light of light irradiated toward a belt. Objective.

  The present invention relates to an image carrier that carries a toner image, a belt that can move in contact with the image carrier, a detection toner image transferred from the image carrier to the belt, and light toward the belt. Detecting means for detecting reflected light from the belt and the detection toner image, and correction control of an image forming condition of an image formed by the toner image based on a detection result of the detection means. An image forming apparatus comprising: a control unit that executes the belt, wherein the belt is a layer that is the thickest layer among the plurality of layers constituting the belt and to which an ionic conductive agent is added in the thickness direction of the belt. It has a certain 1st layer and the 2nd layer whose light transmittance is lower than the said 1st layer, It is characterized by the above-mentioned.

  According to the present invention, in an image forming apparatus that performs correction control on an image by detecting reflected light of light irradiated toward a belt, it is possible to suppress erroneous detection in correction control while ensuring stable transferability. Is possible.

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to a first exemplary embodiment. 2 is a control block diagram of the image forming apparatus. FIG. FIG. 3 is a schematic diagram illustrating the arrangement and configuration of detection means in the first embodiment. 6 is a schematic diagram illustrating a detection toner image when executing correction control for correcting the position of an image in Embodiment 1. FIG. FIG. 3 is a schematic diagram illustrating a configuration of an intermediate transfer belt of Example 1. 6 is a table for explaining light transmittances of intermediate transfer belts of Example 1 and Comparative Example 1. It is a graph which shows the detection result by the detection means in Example 1 and Comparative Example 1. FIG. 6 is a schematic diagram illustrating reflection when infrared light is applied to an intermediate transfer belt in Example 1 and Comparative Example 1. 6 is a schematic diagram illustrating reflection when infrared light is irradiated to a detection toner image in Example 1 and Comparative Example 1. FIG. FIG. 5 is a schematic diagram illustrating a detection toner image when executing correction control for correcting the image density in the first embodiment. 7 is a detection result of a detection toner image when executing correction control for correcting the density of an image in Example 1 and Comparative Example 1. FIG. It is a schematic diagram explaining the structure of the intermediate transfer belt in the other modification. It is a graph explaining wavelength distribution of the light emitting element which has distribution in a wavelength range. It is a graph explaining the relationship between the addition amount of a coloring agent and the transmittance | permeability of infrared light in Example 1 and Example 2. FIG. 6 is a schematic diagram illustrating a configuration of an intermediate transfer belt in Embodiment 4. FIG. FIG. 10 is a schematic diagram illustrating reflected light from an intermediate transfer belt in Example 4. It is a graph which shows the detection result by the detection means in Example 4 and Comparative Example 2.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following examples should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

Example 1
[Description of Image Forming Apparatus]
FIG. 1 is a schematic cross-sectional view showing the configuration of the image forming apparatus 100 of the present embodiment. The image forming apparatus 100 according to the present exemplary embodiment is a so-called tandem type image forming apparatus having a plurality of image forming units Sa to Sd. The first image forming unit Sa is yellow (Y), the second image forming unit Sb is magenta (M), the third image forming unit Sc is cyan (C), and the fourth image forming unit Sd is black (Bk). ) To form an image with each color toner. These four image forming units are arranged in a line at regular intervals, and the configuration of each image forming unit has many portions that are substantially common except for the color of the toner to be accommodated. Therefore, hereinafter, the image forming apparatus of the present embodiment will be described using the first image forming unit Sa.

  The first image forming unit Sa includes a photosensitive drum 1a that is a drum-shaped photosensitive member, a charging roller 2a that is a charging member, a developing unit 4a, and a drum cleaning unit 5a.

  The photosensitive drum 1a is an image carrier that carries a toner image, and is driven to rotate at a predetermined peripheral speed (process speed) in the direction of an arrow R1 in the figure. The developing unit 4a stores yellow toner and develops yellow toner on the photosensitive drum 1a. The drum cleaning unit 5a is a unit for collecting the toner adhering to the photosensitive drum 1a. The drum cleaning unit 5a includes a cleaning blade that contacts the photosensitive drum 1a and a waste toner box that stores toner and the like removed from the photosensitive drum 1a by the cleaning blade.

  When the controller 274 (illustrated in FIG. 2) as a control means receives an image signal and starts an image forming operation, the photosensitive drum 1a is driven to rotate. In the course of rotation, the photosensitive drum 1a is uniformly charged to a predetermined potential (charging potential) with a predetermined polarity (negative polarity in this embodiment) by the charging roller 2a, and exposure according to the image signal is performed by the exposure means 3a. receive. Thereby, an electrostatic latent image corresponding to the yellow component image of the target color image is formed. Next, the electrostatic latent image is developed at the development position by the developing means 4a and visualized as a yellow toner image (hereinafter simply referred to as a toner image). Here, the normal charging polarity of the toner stored in the developing unit 4a is negative. In this embodiment, the electrostatic latent image is reversely developed with the toner charged to the same polarity as the charging polarity of the photosensitive drum by the charging member. However, the present invention uses the toner charged to the opposite polarity to the charging polarity of the photosensitive drum. The present invention can also be applied to an image forming apparatus in which an electrostatic latent image is positively developed.

  The intermediate transfer belt 10 as an endless and movable intermediate transfer member is disposed at a position where it abuts on the photosensitive drums 1a to 1d of the image forming portions Sa to Sd. The roller 12 and the counter roller 13 are stretched around three axes. The intermediate transfer belt 10 is an endless belt having a circumferential length of 700 mm, which is made conductive by adding a conductive agent to a resin material. The intermediate transfer belt 10 is stretched by a tension roller 12 with a total pressure of 60 N and has a driving force. The counter roller 13 that receives and rotates moves in the direction of the arrow R2 in the figure. Although details will be described later, the intermediate transfer belt 10 in the present embodiment is configured by a plurality of layers.

In this embodiment, sleeves made of stainless steel (SUS) are used as the support roller 11 and the stretching roller 12, and the outer diameters of the rollers are 24 mm and 12 mm, respectively. The counter roller 13 is a roller in which a sleeve made of stainless steel (SUS) having an outer diameter of 23 mm is covered with 500 μm thick ethylene propylene diene rubber (EPDM), and has an electric resistance value of 1 × 10. A roller adjusted to ⁵ Ω or less was used. Note that, as in the present embodiment, it is possible to reduce the cost of the member by using a roller of a metal member not covered with a rubber member as the support roller 11 and the stretching roller 12.

  The toner image formed on the photosensitive drum 1a applies a positive voltage from the primary transfer power source 23 to the primary transfer roller 6a in the process of passing through the primary transfer portion N1a where the photosensitive drum 1a and the intermediate transfer belt 10 are in contact with each other. As a result, primary transfer is performed on the intermediate transfer belt 10. Thereafter, the toner remaining on the photosensitive drum 1a without being primarily transferred to the intermediate transfer belt 10 is removed from the surface of the photosensitive drum 1a by being collected by the drum cleaning unit 5a.

  Here, the primary transfer roller 6 a is a primary transfer member (contact member) that is provided at a position corresponding to the photosensitive drum 1 a via the intermediate transfer belt 10 and contacts the inner peripheral surface of the intermediate transfer belt 10. The primary transfer power source 23 is a power source capable of applying a positive or negative voltage to the primary transfer rollers 6a to 6d. In this embodiment, a configuration in which a voltage is applied from a common primary transfer power supply 23 to a plurality of primary transfer members will be described. However, the present invention is not limited to this, and a plurality of primary transfer power supplies are associated with each primary transfer member. The present invention can be applied even if the configuration is provided.

  Thereafter, similarly, a second color magenta toner image, a third color cyan toner image, and a fourth color black toner image are formed and sequentially transferred onto the intermediate transfer belt 10. As a result, four color toner images corresponding to the target color image are formed on the intermediate transfer belt 10. Thereafter, the four color toner images carried on the intermediate transfer belt 10 are fed by the paper feeding means 50 in the process of passing through the secondary transfer portion formed by the contact between the secondary transfer roller 20 and the intermediate transfer belt 10. Secondary transfer is performed collectively on the surface of a transfer material P such as paper or an OHP sheet.

  The secondary transfer roller 20 is a nickel-plated steel rod having an outer diameter of 6 mm and an outer diameter of 18 mm covered with a foamed sponge body mainly composed of NBR and epichlorohydrin rubber adjusted to a volume resistivity of 108 Ω · cm and a thickness of 6 mm. Is used. The rubber hardness of the foamed sponge body was measured using an Asker hardness meter C type, and the hardness was 30 ° when loaded with 500 g. The secondary transfer roller 20 is in contact with the outer peripheral surface of the intermediate transfer belt 10, and a pressure of 50 N is applied to the opposing roller 13 disposed at a position facing the secondary transfer roller 20 via the intermediate transfer belt 10. To form a secondary transfer portion N2.

  The secondary transfer roller 20 is driven to rotate with respect to the intermediate transfer belt 10, and a current flows from the secondary transfer roller 20 toward the counter roller 13 when a voltage is applied from the secondary transfer power supply 21. As a result, the toner image carried on the intermediate transfer belt 10 is secondarily transferred to the transfer material P in the secondary transfer portion. When the toner image on the intermediate transfer belt 10 is secondarily transferred to the transfer material P, the current flowing from the secondary transfer roller 20 toward the counter roller 13 via the intermediate transfer belt 10 is constant. The voltage applied from the secondary transfer power source 21 to the secondary transfer roller 20 is controlled. Further, the magnitude of the current for performing the secondary transfer is determined in advance according to the surrounding environment in which the image forming apparatus 100 is installed and the type of the transfer material P. The secondary transfer power source 21 is connected to the secondary transfer roller 20 and applies a transfer voltage to the secondary transfer roller 20. The secondary transfer power source 21 can output in the range of 100 [V] to 4000 [V].

  The transfer material P onto which the four color toner images have been transferred by the secondary transfer is then heated and pressurized by the fixing means 30, whereby the four color toners are melted and mixed and fixed onto the transfer material P. The toner remaining on the intermediate transfer belt 10 after the secondary transfer is cleaned and removed by a belt cleaning unit 16 provided to face the opposing roller 13 via the intermediate transfer belt 10. The belt cleaning unit 16 includes a cleaning blade 16a (cleaning member) that contacts the outer peripheral surface of the intermediate transfer belt 10 at a position facing the counter roller 13, a waste toner container 16b that stores toner collected by the cleaning blade 16a, Have

  In the image forming apparatus 100 of the present embodiment, a full-color print image is formed by the above operation.

[Explanation of control block diagram]
FIG. 2 is a control block diagram for controlling an image forming operation in the image forming apparatus 100. The personal computer 271 as the host device issues an image formation start command to the formatter 273 in the image forming apparatus 100 and transmits image data to be formed to the formatter 273. The formatter 273 converts the image data transmitted from the personal computer 271 into exposure data, and transfers the exposure data to the controller 274 as control means. The controller 274 is equipped with a CPU 276, a memory 275, and the like, and can perform pre-programmed operations. When an image formation start command is received from the formatter 273, the CPU 276 mounted on the controller 274 controls various means to perform an image forming operation.

  Further, the CPU 276 outputs from the first sensor 40 a and the second sensor 40 b provided in the detection unit 40 when executing correction control for correcting the image forming conditions such as the position and density of the image formed in the image forming apparatus 100. Processing to receive signals is also performed. In the image forming condition correction control, the amount of reflected light from the outer peripheral surface of the intermediate transfer belt 10 at a position facing the detection unit 40 and the test patch (detection toner image) formed on the intermediate transfer belt 10 is measured. Detection signals from the first sensor 40 a and the second sensor 40 b are AD converted via the CPU 276 and then stored in the memory 275. The controller 274 performs calculations using the detection results of the first sensor 40a and the second sensor 40b, and performs various corrections.

[Detection means]
Next, the detection means 40 will be described. The detection unit 40 detects reflected light from the outer peripheral surface of the intermediate transfer belt 10 and a test patch formed on the intermediate transfer belt 10. Here, specifically, the test patch includes a misregistration control pattern for detecting a misregistration of an image forming position and a density control pattern for detecting the density of an image.

  FIG. 3A is a schematic diagram illustrating the configuration of the detection unit 40. 3B is a schematic diagram for explaining the configuration of a first sensor 40a (first detection member) provided in the detection means 40, and FIG. 3C is a second view provided in the detection means 40. It is a schematic diagram explaining the structure of the sensor 40b (2nd detection member).

  As shown in FIG. 3A, the detection means 40 has two sensors, a first sensor 40a and a second sensor 40b, and the first sensor 40a and the second sensor 40b are held by a stay 40c as a holding member. Has been. Further, the first sensor 40 a and the second sensor 40 b are arranged on the opposite sides with respect to the width direction orthogonal to the moving direction of the intermediate transfer belt 10 via a line segment CL that is the center line of the intermediate transfer belt 10. . In the present embodiment, the distances from the line segment CL to the first sensor 40a and the second sensor 40b are each 90 mm.

  As shown in FIG. 3B, the first sensor 40a includes a light emitting element 41a such as an LED, light receiving elements 42a and 43a such as a phototransistor, and a holder 44a. The light emitting element 41a is disposed so as to have an inclination of 15 ° with respect to the intermediate transfer belt 10, and infrared light (for example, wavelength 800 nm) is applied to the test patch on the intermediate transfer belt 10 or the surface of the intermediate transfer belt 10. Irradiate. The region irradiated with the infrared light is a detection region, and the shape of the holder 44a is adjusted so that the spot diameter is 2 mm when the intermediate transfer belt 10 is irradiated with infrared light from the light emitting element 41a. ing.

  The light receiving element 43 a is disposed so as to have a 45 ° inclination with respect to the intermediate transfer belt 10, and receives infrared light diffusely reflected from the surface of the test patch or the intermediate transfer belt 10. The light receiving element 42 a is arranged so as to have a 15 ° inclination with respect to the intermediate transfer belt 10, and receives infrared light that is specularly reflected and diffusely reflected from the surface of the test patch or the intermediate transfer belt 10. According to the first sensor 40a, it is possible to detect a test patch such as a misregistration control pattern or a density control pattern.

  As shown in FIG. 3C, the second sensor 40b includes a light emitting element 41b such as an LED, a light receiving element 43b such as a phototransistor, and a holder 44b. The light emitting element 41b is arranged to have an inclination of 15 ° with respect to the intermediate transfer belt 10, and the characteristics as the element are the same as the light emitting element 41a. The light receiving element 43b is arranged to have an inclination of 45 ° with respect to the intermediate transfer belt 10, and the characteristics as the element are the same as those of the light receiving element 43a. According to the second sensor 40b, it is possible to detect a test patch of a positional deviation control pattern.

[Description of correction control of image forming conditions]
FIG. 4 shows a test patch formed on the intermediate transfer belt 10 when the correction control (hereinafter referred to as registration correction) for correcting the position of the image in the present embodiment, the first sensor 40a and the second sensor. It is a schematic diagram explaining the positional relationship with 40b. As shown in FIG. 4, when performing registration correction, test patches 200 and 300 for misregistration control patterns are formed at positions corresponding to the first sensor 40 a and the second sensor 40 b, respectively. The test patch 200 and the test patch 300 are formed so that yellow (Y), magenta (M), cyan (C), and black (Bk) parallelogram patches are symmetrical with respect to the reference line. .

  The test patch 200 and the test patch 300 move as the intermediate transfer belt 10 moves, and the infrared light irradiated from the light emitting element 41a is passed while the detection means 40 and the intermediate transfer belt 10 pass through the opposing positions. Diffuse reflection. The registration correction is performed based on the result of detecting the diffuse reflected light of the infrared light irradiated toward the test patch 200 and the test patch 300 by the first sensor 40a and the second sensor 40b.

  Of the infrared light emitted from the light emitting element 41a and the light emitting element 41b provided in each sensor, the reflected light from the intermediate transfer belt 10 is mainly regular reflected light, and is yellow (Y), magenta (M), cyan. The reflected light from the toner (C) is diffusely reflected light. That is, the toner of each color of the test patch 200 or the test patch 300 is detected by detecting the timing when the detection waveform of the diffuse reflected light exceeds the preset threshold when the infrared light is irradiated from the light emitting element 41a or the light emitting element 41b. It is possible to identify the position by detecting the edge. As for the black toner, infrared light is mainly absorbed. Therefore, as shown in FIG. 4, the position of the black toner can be specified by superimposing the black toner and the other color toner.

  The received intensity of the diffusely reflected light received by the light receiving elements 43a and 43b is converted into a voltage by the controller 274. Here, as the dynamic range, which is the difference between the detection output of the intermediate transfer belt 10 and the detection output of the test patch 200 and the test patch 300, is wider, the edge of the toner is stably detected without being influenced by external noise or the like. be able to.

  The controller 274 detects the passage timing of the test patch 200 and the test patch 300 based on the output from the detection means 40, and calculates the position. Then, by comparing it with a predetermined timing, the relative color misregistration amount between the toners of each color in the main scanning direction and the sub scanning direction, the magnification in the main scanning direction, the relative inclination, and the like are calculated. Registration correction is performed by correcting the relative position of the toner of each color according to the result.

[Description of intermediate transfer belt]
When the intermediate transfer belt is highly transmissive and the irradiation light from the detection means 40 passes through the intermediate transfer belt and the reflected light from the opposite object is generated, the above-mentioned dynamic range may be lowered. Therefore, in order to perform stable detection, it is necessary to reduce the permeability of the intermediate transfer belt.

  FIG. 5 is a diagram illustrating a cross section of the intermediate transfer belt 10 in this embodiment. As shown in FIG. 5, the intermediate transfer belt 10 has a base layer 10a (first layer) and an inner surface layer 10b (second layer) as an infrared light absorption layer. Here, the base layer is defined as the thickest layer among the layers constituting the intermediate transfer belt 10 in the thickness direction of the intermediate transfer belt 10. In this example, the inner surface layer 10b was formed by spray coating on the inner peripheral surface of the base layer 10a, and the intermediate transfer belt 10 having a plurality of layers was obtained by molding by blow molding. The thickness t1 of the base layer 10a after blow molding is 64 μm, and the thickness t2 of the inner surface layer 10b is 1 μm. The thickness t <b> 1 of the base layer 10 a is preferably in the range of 55 to 85 μm in consideration of handling properties at the time of assembly and the stretched traces by the support roller 11, the stretch roller 12, and the counter roller 13.

  In this embodiment, the intermediate transfer belt 10 has a circumferential length difference of 0.5 mm or less and film thickness unevenness of 15 μm or less at both ends in the width direction (main scanning direction) orthogonal to the moving direction of the intermediate transfer belt 10. The blow molding temperature, speed, etc. are optimized. Further, the blow molding temperature, speed, and the like of the intermediate transfer belt 10 are optimized so that the elastic modulus of the intermediate transfer belt 10 is about 2000 MPa. As a method for forming the intermediate transfer belt 10, in addition to blow molding, there are, for example, centrifugal molding, tube extrusion, inflation molding, extrusion molding, and cylindrical extrusion molding.

The base layer 10a is composed of endless polyethylene naphthalate (PEN) in which an ionic conductive agent is mixed as a conductive agent, and 0.1% by mass of a dye is added to perform blow molding. In addition, the amount of the ion conductive agent added to the base layer 10a is adjusted so that the volume resistivity of the intermediate transfer belt 10 is 5 × 10 ⁹ Ω · cm. The volume resistivity of the base layer 10a may be in the range of 1 × 10 ⁸ to 1 × 10 ¹² Ω · cm, and more preferably in the range of 1 × 10 ⁸ to 1 × 10 ¹¹ Ω · cm. Further, the base layer 10a has a surface glossiness adjusted to 30 or more so that the infrared light irradiated from the detection means 40 is regularly reflected on the surface of the intermediate transfer belt 10 (manufactured by Horiba: Handy glossiness meter). Measured with IG-320).

The inner surface layer 10b is made of polyurethane in which 50% by mass of a phthalocyanine dye pigment is mixed as a colorant. Further, the resistance value of the inner surface layer 10b is adjusted in the range of 1 × 10 ⁴ to 1 × 10 ¹⁰ Ω · cm by the addition of the ionic conductive agent.

Here, the surface resistivity when measured from the outer peripheral surface side of the intermediate transfer belt 10 is defined as the surface resistivity of the base layer 10, and when measured from the inner peripheral surface side (the inner surface layer 10 b side) of the intermediate transfer belt 10. The surface resistivity is defined as the surface resistivity of the inner surface layer 10b. In the configuration of this example, the surface resistivity of the base layer 10a may be in the range of 5.0 × 10 ⁸ Ω / □ to 1.0 × 10 ¹² Ω / □, and 1.0 × 10 ^9.5. A range of Ω / □ to 1.0 × 10 ¹¹ Ω / □ is more preferable. Further, the surface resistivity of the inner surface layer 10b may be in the range of 1.0 × 10 ⁷ Ω / □ or less, and more preferably in the range of 1.0 × 10 ⁶ Ω / □ or less.

  The volume resistivity and surface resistivity of the intermediate transfer belt 10 were measured using a Hiresta-UP (MCP-HT450) manufactured by Mitsubishi Chemical Corporation under a measurement environment at a temperature of 23 ° C. and a humidity of 50%. The volume resistivity is measured by using a ring probe type UR (model MCP-HTP12), applying the probe from the outer peripheral surface side of the intermediate transfer belt 10 and applying voltage 100 [V] and measuring time 10 seconds. It was. The surface resistivity is measured using a ring probe type UR100 (model MCP-HTP16). The applied voltage is 100 V on the outer peripheral surface side, the measuring time is 10 seconds, the applied voltage is 10 [V] on the inner peripheral surface side, and the measuring time is 10 Performed under the condition of seconds. The surface resistivity on the inner peripheral surface side of the intermediate transfer belt 10, that is, the surface resistivity of the inner surface layer 10b was measured by applying a probe to the inner surface layer 10b side. The surface resistivity on the outer peripheral surface side of the intermediate transfer belt 10, that is, the base layer 10, was measured by applying a probe to the base layer 10a side.

[Operation and effect of this embodiment]
FIG. 6 shows the result of measuring the light transmittance at a wavelength of 800 nm of the intermediate transfer belt in this example and Comparative Example 1. The measurement was performed by using an ultraviolet-visible infrared spectrophotometer (Hitachi High-Tech Science UH4150) and placing the intermediate transfer belt 10 between the light emitting part and the detecting part of the spectrophotometer. More specifically, the distance between the light emitting portion and the intermediate transfer belt 10 was 290 mm, and the distance between the intermediate transfer belt 10 and the detection portion was 190 mm. Note that the intermediate transfer belt of Comparative Example 1 does not have the inner surface layer 10b in the intermediate transfer belt 10 of this embodiment, but has only a layer corresponding to the base layer 10a.

  As shown in FIG. 6, the light transmittance with respect to the light with a wavelength of 800 nm in this example is 2.0%, and the infrared light is hardly transmitted. On the other hand, since the intermediate transfer belt of Comparative Example 1 does not have the inner surface layer 10b, the light transmittance is higher than that of the intermediate transfer belt 10 of this example, and the light transmittance with respect to light having a wavelength of 800 nm is 12%. It was.

  FIG. 7A shows the diffuse reflection light from the surface of the intermediate transfer belt and the test patch formed on the intermediate transfer belt detected by the light receiving element 43a when the intermediate transfer belt of this embodiment and comparative example 1 is used. It is a result. 7B is a ratio obtained by dividing the detection output of the surface of the intermediate transfer belt from the detection output of the test patch in the present embodiment and the comparative example 1 based on the detection result of FIG. 7A. , Dynamic range indicator. The larger the value on the vertical axis is, the larger the dynamic range is, indicating that the test patch can be detected stably.

  As shown in FIG. 7A, in the configuration of this example, the detection result of the diffuse reflected light from the surface of the intermediate transfer belt 10 obtained by the light receiving element 43a was 0.3V. On the other hand, in the configuration of Comparative Example 1, the detection result of the diffuse reflected light from the surface of the intermediate transfer belt was 1.8 V, which was a higher value than that of the present example. The reason for this will be described with reference to FIGS. FIG. 8A is a schematic diagram for explaining the reflection of infrared light when the intermediate transfer belt 10 is irradiated with infrared light in the configuration of the present embodiment. FIG. 8B is a schematic diagram for explaining the reflection of infrared light when the intermediate transfer belt is irradiated with infrared light in the configuration of Comparative Example 1.

  As shown in FIG. 8A, when the intermediate transfer belt 10 is irradiated with infrared light, the infrared light is slightly diffusely reflected on the surface of the base layer 10a, and a part of the infrared light transmitted through the base layer 10a is reflected on the inner surface. Absorbed by layer 10b. On the other hand, in the configuration of Comparative Example 1 that does not have the inner surface layer 10b, as shown in FIG. 8 (b), when the intermediate transfer belt is irradiated with infrared light, diffuse reflected light from the surface of the intermediate transfer belt is reflected. In addition, part of the infrared light transmitted through the intermediate transfer belt is diffusely reflected on the surface of the support roller 11. In particular, the support roller 11 made of stainless steel as a metal member easily reflects infrared light because of its surface characteristics. As a result, as shown in FIG. 7A, in the configuration of Comparative Example 1, the detection result of the diffuse reflected light from the surface of the intermediate transfer belt was larger than that in this example.

  Further, as shown in FIG. 7A, in the configuration of this example, the detection result of the diffuse reflected light from the test patch obtained by the light receiving element 43a was 2.1V. On the other hand, in the configuration of Comparative Example 1, the detection result of the diffuse reflected light from the test patch was 3.0 V, which was a higher value than that of the present example. The reason for this will be described with reference to FIGS. FIG. 9A is a schematic diagram for explaining the reflection of infrared light when the test patch formed on the intermediate transfer belt 10 is irradiated with infrared light in the configuration of this embodiment. FIG. 9B is a schematic diagram for explaining the reflection of infrared light when the test patch formed on the intermediate transfer belt is irradiated with infrared light in the configuration of Comparative Example 1.

  As shown in FIG. 9A, when the test patch formed on the intermediate transfer belt 10 is irradiated with infrared light, the infrared light is diffusely reflected on the surface of the test patch and transmitted through the test patch and the base layer 10a. Part of the infrared light is absorbed by the inner surface layer 10b. On the other hand, in the configuration of Comparative Example 1 that does not have the inner surface layer 10b, as shown in FIG. 9B, in addition to the infrared light diffusely reflected on the surface of the test patch, the test patch and the intermediate transfer belt are Part of the transmitted infrared light is diffusely reflected on the surface of the support roller 11. As a result, as shown in FIG. 7A, in the configuration of Comparative Example 1, the detection result of the diffuse reflected light from the surface of the test patch was larger than that in the present example.

  As shown in FIG. 7B, in the configuration of this example, the value of the dynamic range obtained from the detection result of FIG. 7A was 7.0. From this result, the registration correction can be stably performed in the configuration of the present embodiment regardless of disturbances such as the deterioration of the intermediate transfer belt 10 at the time of occurrence and the contamination of each sensor of the detection means 40. On the other hand, in the configuration of Comparative Example 1, the value of the dynamic range is 1.7, which is a lower value than the present example. In other words, when the intermediate transfer belt of Comparative Example 1 is used, the dynamic range cannot be secured firmly due to disturbances such as deterioration of the intermediate transfer belt at the time of passage and sensor contamination, and the registration correction is stably performed. It may not be possible.

  As described above, in this embodiment, by providing the inner surface layer 10b as the infrared light absorption layer on the inner peripheral surface side of the base layer 10a, the uniformity of the electric resistance value of the intermediate transfer belt 10 is not impaired. Further, it is possible to reduce the permeability of the intermediate transfer belt. As a result, when the correction control for correcting the image forming conditions such as the position and density of the image is executed, the light emitted from the detection unit 40 to the intermediate transfer belt 10 and the test patch passes through the intermediate transfer belt 10. Occurrence of erroneous detection due to this can be suppressed.

  If the suppression of light transmittance by the inner surface layer 10b is 7.5% or less, the dynamic range becomes 3.0 or more, and stable registration detection can be expected. More preferably, the light transmittance is 6% or less, and the dynamic range is preferably 4.0 or more.

  In this embodiment, an example of performing registration correction using the detection result of diffuse reflection light has been described. However, the present invention is not limited to this, and registration correction can also be performed using the detection result of specular reflection light. . Even in this case, the detection accuracy of the correction control can be stabilized by providing the inner surface layer 10b.

  When performing registration correction based on the detection result of the specularly reflected light, the light receiving element 42a that detects the specularly reflected light exhibits a strong light receiving intensity with respect to the intermediate transfer belt 10, while receiving light with respect to the test patch. Correction control is performed using the fact that the intensity is weakened. More specifically, since the light receiving element 42a receives only the reflected light in the regular reflection direction out of the diffuse reflected light from the test patch, the light receiving intensity is weak at the boundary between the intermediate transfer belt 10 and the test patch. Therefore, the position of the test patch can be specified by detecting the timing when the detection output crosses the predetermined threshold before and after passing through the test patch.

  In addition, in the case of regular reflection light detection, there is a characteristic that the reflection direction changes and the received light intensity greatly changes depending on the surface irregularities of the reflector. For this reason, when foreign matter from the outside, shaving powder or the like of the intermediate transfer belt 10 accumulates on the support roller 11, if infrared light passes through the intermediate transfer belt 10 and is irradiated to the foreign matter, it will be in the regular reflection direction. Due to the reduction of the reflection component, there is a possibility that foreign matter is erroneously detected as a test patch. According to the configuration of the present embodiment, since the inner layer 10b is formed, the transmission of the intermediate transfer belt 10 out of the infrared light irradiated from the detection means 40 is absorbed by the inner layer 10b. Such false detection can be prevented.

  In the present embodiment, registration correction has been described. However, the present invention is not limited to this, and the present invention is also effective when performing density correction for correcting the density of an image as correction control for image forming conditions by the detection means 40. Hereinafter, the density correction will be briefly described with reference to FIGS. 10 and 11A to 11B. FIG. 10 is a schematic diagram of a test patch 400 formed on the intermediate transfer belt 10 when density correction is executed. FIG. 11A is a graph of the detection result of the test patch 400 in the configuration of this example, and FIG. 11B is the configuration of Comparative Example 1 in which the inner surface layer 10b is not provided on the intermediate transfer belt. 4 is a graph of detection results of a test patch 400.

  As shown in FIG. 10, when density correction is performed, yellow (Y), magenta (M), cyan (C), and black (Bk) are 5 at positions corresponding to the first sensor 40a of the intermediate transfer belt 10, respectively. A pattern is formed for each gradation. The detection result of the test patch 400 by the first sensor 40a is processed by the controller 274. Specifically, the received light amount signal of the first sensor 40a is A / D (analog / digital) converted and then output to the controller 274, and the CPU 276 in the controller 274 calculates the net specular reflected light amount. Based on this result, the controller 274 sets density factors such as a charging voltage, a developing voltage, and an exposure light amount. The setting result of the density factor is stored in the memory 275 in the controller 274, and is used when an image is formed or when the next density correction is executed.

  Here, as an example, FIG. 11A shows the detection result of the yellow gradation pattern of the test patch 400 in the configuration of the present embodiment. In the density correction, the detection output is normalized so that the detection output of the specular reflection light and the detection output of the diffuse reflection light in the patch 401Y having a toner amount (density) of 100% is equal, and the difference between the specular reflection output and the scattered reflection output To calculate the net specular reflection light quantity. By performing such calculation, a graph after the calculation as shown in FIG. 11A is obtained, and density correction is performed based on the result corresponding to the toner amount. In this embodiment, yellow has been described as an example, but magenta, cyan, and black can be calculated in the same manner.

  As shown in FIG. 11B, in the configuration of Comparative Example 1 using the intermediate transfer belt not provided with the inner surface layer 10b, the net specular reflected light amount after the calculation in the case where the toner amount is zero is greater than that of this embodiment. Lower. In the configuration of Comparative Example 1, the infrared light irradiated from the light emitting element 41 b passes through the intermediate transfer belt and diffusely reflects on the surface of the support roller 11. As a result of detecting the diffuse reflected light by the light receiving element 43b, the detection output of the light receiving element 43b is not zero even when the toner amount is zero, as indicated by a point A in FIG. 11B. It becomes. As a result, as shown in FIGS. 11A and 11B, the dynamic range in the configuration of the comparative example 1 is compared with the dynamic range in the configuration of the present embodiment using the intermediate transfer belt 10 having the inner surface layer 10b. The range becomes narrow. Therefore, also in the density correction, it is desirable to form the inner surface layer 10b and absorb the transmitted light of the base layer 10a by the inner surface layer 10b as in this embodiment.

  In this embodiment, PEN is used as the resin material for the base material of the intermediate transfer belt 10, but a thermoplastic resin, a thermosetting resin, or the like can be used. Furthermore, other additives such as a conductive polymer or electrolyte as a conductive agent, a compatibilizing agent, a dispersant, and various fillers can be added depending on the required performance.

  In this embodiment, 0.1% by mass of a dye is added as a colorant added to the base layer 10a. However, the addition of a colorant can further suppress the transmission of infrared light. Since the base layer 10a is thicker than the inner surface layer 10b, transmission of infrared light can be suppressed with a small addition amount. However, it is desirable to adjust the addition of the colorant to the base layer 10a within a range of 0.5 mass% or less in order to make the variation of the electric resistance of the intermediate transfer belt 10 and the formability not problematic.

  In this embodiment, 50% by mass of a phthalocyanine-based dye pigment is added to the inner surface layer 10b having a thickness of 1 μm. In order to further suppress the transmission of infrared light, the inner surface layer 10b can be made thicker. Good. For example, if the thickness of the inner surface layer 10b is 2 μm, the amount of phthalocyanine dye added to the thickness of 2 μm is twice that of when the thickness is 1 μm, so that the infrared light is more transmitted. It is reduced. When the thickness of the inner surface layer 10b is increased to 4 μm, the transmittance is almost 0%.

  Even if the film thickness of the inner surface layer 10b is 1 μm, it is possible to reduce the transmittance of infrared light by increasing the phthalocyanine dye coloring matter. For example, when 75% by mass of a dye pigment is added, the transmittance is almost 0%. The addition amount of the phthalocyanine-based dye pigment may be appropriately adjusted in view of material costs and a range in which a desired dynamic range can be obtained. In the configuration of the image forming apparatus 100 of the present embodiment, if the addition amount of the phthalocyanine-based dye pigment is 40% by mass or more, the infrared light transmittance is 4% or less, and a sufficient effect is obtained. The thickness of the inner surface layer 10b may be 1 μm or more in view of the transmittance of infrared light, and is appropriate in view of preventing the intermediate transfer belt 10 from cracking due to the increased hardness of the intermediate transfer belt 10. In order to ensure flexibility, it may be 10 μm or less.

  Polyurethane is used as the material used for the inner surface layer 10b, but a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, or the like can be used. Moreover, as a shaping | molding method of the inner surface layer 10b, the two-color shaping | molding with the base material by spin coat and roll coat etc. is mentioned other than spray coating, for example. Further, in this embodiment, the inner surface layer 10b is formed on the inner peripheral surface side of the intermediate transfer belt 10, but not limited to this, the infrared light absorbing layer of the present embodiment is provided on the outer peripheral surface side of the intermediate transfer belt 10. Even if it is provided, it is possible to obtain the same effect as in this embodiment. When the infrared light absorption layer is provided on the outer peripheral surface side of the intermediate transfer belt 10, it may be formed by spray coating similarly to the inner surface layer 10b of this embodiment, or may be formed by other methods described above.

  In the present embodiment, the configuration in which the first sensor 40a capable of detecting regular reflection light and diffuse reflection light and the second sensor 40b capable of detecting diffuse reflection light are provided as the detection means 40, respectively. However, the present invention is not limited to this, and both of the two sensors may be sensors that can detect regular reflection light and diffuse reflection light. Alternatively, the second sensor 40b may include only a light receiving element that detects specularly reflected light and may not include a light receiving element that detects diffusely reflected light. One may detect specularly reflected light and the other may be diffusely reflected light. It is good also as a sensor which detects. According to the configuration in which both of the two sensors are not sensors capable of detecting specular reflection light and diffuse reflection light as in the present embodiment, the light receiving element for detecting the specular reflection light is not provided in the second sensor 40b. It is possible to achieve simplification of the configuration of the second sensor 40b and cost reduction.

  Further, in order to detect a positional deviation in the main scanning direction when performing registration correction, it is preferable to provide two sensors as in the present embodiment, but the present invention is not limited to this, and one first sensor 40a is provided. May be provided, or the number of sensors may be increased to three or more.

  In this embodiment, the inner surface layer 10 b is formed on the entire inner peripheral surface side of the base layer 10 a of the intermediate transfer belt 10. However, the present invention is not limited to this, and as shown in FIG. 12, the inner surface layer 10b may be formed only at positions corresponding to the first sensor 40a and the second sensor 40b. As long as the inner surface layer 10b is formed in a region of one circumference of the intermediate transfer belt 10 that faces the position where the first sensor 40a and the second sensor 40b are disposed at least in the width direction of the intermediate transfer belt 10. Good. The inner surface layer 10b is applied to the back side of the base layer 10a by spray coating, spin coating, roll coating, or the like. The larger the coating area, the longer it takes to form the layer, and the larger the coating area, the higher the material cost. To do. Therefore, by applying the inner surface layer 10b to the minimum necessary region as shown in FIG. 12, it is possible to reduce the formation process time and material cost.

(Example 2)
In the first embodiment, the configuration in which a phthalocyanine-based dye pigment is used as the colorant for the inner surface layer 10b has been described. On the other hand, in Example 2, a configuration using carbon black as a colorant for the inner surface layer 110b will be described. The configuration of this example is substantially the same as that of Example 1 except that carbon black is used as the colorant for the inner surface layer 110b. Therefore, in the following description, the same reference numerals are assigned to portions common to the first embodiment, and description thereof is omitted.

  In the case of a dye pigment, when only a single compound is added, the absorption efficiency is high in a specific wavelength region, while the absorption efficiency is decreased in other wavelength regions. For this reason, for example, when the light emitting elements having a distribution in the wavelength region as shown in FIG. 13 or the peak wavelength varies due to individual variation of the light emitting elements, the irradiation light in a part of the wavelength region is transmitted through the inner surface layer 10b. There is a possibility that. In order to sufficiently obtain the effect of absorbing infrared light by the inner surface layer 10b, it is necessary to add a dye capable of widely absorbing infrared light in the vicinity of 800 nm which is the peak wavelength of the light emitting elements 41a and 41b. However, when a dye pigment is used as the colorant, it is necessary to add and mix a plurality of compounds, which may increase the amount of addition.

  Therefore, in this embodiment, carbon black is added to the inner surface layer 110b as a colorant that can absorb a wide range of light in the infrared wavelength region with a small addition amount. FIG. 14 is a graph illustrating the relationship between the amount of colorant added and the infrared light transmittance in each of the intermediate transfer belts of Example 1 and Example 2. As shown in FIG. 14, when compared with the same addition amount, the infrared light transmittance in the intermediate transfer belt 110 in which carbon black is added to the inner surface layer 110b is intermediate between the addition of a phthalocyanine-based dye pigment to the inner surface layer 10b. It is lower than the transmittance of infrared light in the transfer belt 10.

  That is, when carbon black is used as the colorant, the same infrared light absorption efficiency can be obtained with a smaller addition amount than the phthalocyanine dye pigment. As described above, in this embodiment, by adding carbon black as a colorant to the inner surface layer 110b, not only the same effects as those of the first embodiment can be obtained, but also the inner surface of which the infrared light absorption rate is further improved. It becomes possible to obtain the layer 110b.

  In the configuration of this example, if the amount of carbon black added to the inner surface layer 110b is 5% by mass or more, the infrared light transmittance is 4% or less, and a sufficient effect is obtained. On the other hand, when the amount of carbon black added to the inner surface layer 110b increases, the inner surface layer 110b may be scraped by contact with the support rollers 11, 12, and 13 when the intermediate transfer belt 110 is rotationally moved. Therefore, the amount of carbon black added to the inner surface layer 110b is desirably 5% by mass to 50% by mass. More preferably, it is 5 to 20% of range.

  Further, in this embodiment, the intermediate transfer belt 110 in which the electric resistance of the base layer 110a and the inner surface layer 110b is different by adding carbon black is used, and the electric resistance of the inner surface layer 110b is set lower than that of the base layer 110a. ing. Here, regarding the intermediate transfer belt 110, the surface resistivity measured from the outer peripheral surface side (base layer 110a side) is defined as the electric resistance of the base layer 110a, and the surface resistivity measured from the inner peripheral surface side (inner surface layer 110b side) is defined as the inner surface layer. It is defined as an electric resistance of 110b. That is, the intermediate transfer belt 110 of this embodiment has different surface resistivity values measured from the outer peripheral surface side and surface resistivity values measured from the inner peripheral surface side, and the surface resistivity measured from the inner peripheral surface side is different. Is smaller than the surface resistivity measured from the outer peripheral surface side.

Further, in the intermediate transfer belt 110 in this embodiment, the volume resistivity of the intermediate transfer belt 110 reflects the electric resistance of the base layer 110a because of the relationship between the electrical resistance and thickness of the base layer 110a and the inner surface layer 110b. In a standard environment (temperature 23 ° C., humidity 50%), the surface resistivity measured from the outer peripheral surface side of the intermediate transfer belt 110 is 3.2 × 10 ⁹ Ω / □, and measured from the inner peripheral surface side of the intermediate transfer belt 110. The surface resistivity was 1.0 × 10 ⁶ Ω / □. The volume resistivity was 5 × 10 ⁹ Ω · cm. The preferable resistivity range of the intermediate transfer belt 110 is 5.0 × 10 ⁸ Ω / □ to 1.0 × 10 ¹¹ Ω / □ in terms of surface resistivity, and 5.0 × 10 ⁸ Ω · in volume resistivity. cm to 8.0 × 10 ¹¹ Ω · cm.

Here, it is desirable that the resistivity of the intermediate transfer belt 110 in the configuration of this embodiment be set in the following range. The electric resistance of the base layer 110a, that is, the surface resistivity measured from the outer peripheral surface side of the intermediate transfer belt 110 may be set in the range of 5.0 × 10 ⁸ Ω / □ to 1.0 × 10 ¹² Ω / □. preferable. More preferably, it is 1.0 × 10 ^9.5 Ω / □ to 1.0 × 10 ¹¹ Ω / □. The preferable resistivity range on the inner peripheral surface side is 1.0 × 10 ⁷ Ω / □ or less, and more preferably 1.0 × 10 ⁶ Ω / □ or less in terms of surface resistivity. The volume resistivity is 5.0 × 10 ⁸ Ω · cm to 8.0 × 10 ¹¹ Ω · cm.

  The volume resistivity and surface resistivity of the intermediate transfer belt 110 were measured using a Hiresta-UP (MCP-HT450) manufactured by Mitsubishi Chemical Corporation under a measurement environment at a temperature of 23 ° C. and a humidity of 50%. The volume resistivity is measured by using a ring probe type UR (model MCP-HTP12), applying the probe from the outer peripheral surface side of the intermediate transfer belt 110, and applying voltage 100 [V] and measuring time 10 seconds. It was. The surface resistivity is measured by using a ring probe type UR100 (model MCP-HTP16). The applied voltage is 100 V on the outer peripheral surface side, the measuring time is 10 seconds, the applied voltage is 10 [V] on the inner peripheral surface side, and the measuring time is 10 Performed under the condition of seconds. The surface resistivity on the inner peripheral surface side of the intermediate transfer belt 110 is measured by applying a probe to the inner surface layer 110b side, and the surface resistivity on the outer peripheral surface side of the intermediate transfer belt 110 is measured by applying a probe to the base layer 110a side. did.

(Example 3)
In Example 2, carbon black was added as a colorant. Carbon black is an aggregate of particles having a diameter of 3 nm to 500 nm, and the transmittance of infrared light varies depending on the particle diameter and the structure of the aggregate. As the particle size is smaller, the transmittance of infrared light tends to decrease, but the dispersibility of carbon black tends to decrease, and the transmittance may be uneven. Further, when the aggregate structure is increased, the dispersibility is improved and unevenness in transmittance tends to be reduced, while the transmittance of infrared light tends to increase. When carbon black is used as the colorant, it is possible to achieve both reduction in infrared light transmittance and suppression of transmittance unevenness by increasing the amount of carbon black added.

  Therefore, the third embodiment is characterized in that carbon nanotubes are added to the inner surface layer 210b as a colorant capable of reducing the transmittance of infrared light with a smaller addition amount. The configuration of this example is substantially the same as that of Example 1 except that carbon nanotubes are used as the colorant for the inner surface layer 210b. Therefore, in the following description, the same reference numerals are assigned to portions common to the first embodiment, and description thereof is omitted.

  In this embodiment, cylindrical carbon nanotubes in which general carbon six-membered ring structures are connected are dispersed in polyurethane which is a base material of the inner surface layer 210b of the intermediate transfer belt 210. By using the carbon nanotubes having a cylindrical structure as a colorant, the infrared light transmitted through the base layer 210a of the intermediate transfer belt 210 is repeatedly reflected and attenuated within the cylindrical structure of the carbon nanotubes dispersed in the inner surface layer 210b. As a result, in this embodiment, the intermediate transfer belt 210 that not only obtains the same effects as those of the first and second embodiments but also reduces the amount of the colorant added while reducing the infrared light transmission property. It is possible to obtain.

Example 4
In the first embodiment, the intermediate transfer belt 10 having the base layer 10a and the inner surface layer 10b has been described. On the other hand, as shown in FIGS. 15A to 15B, the intermediate transfer belt 310 of Example 4 has grooves formed in the moving direction of the base layer 310a, the inner surface layer 310b, and the intermediate transfer belt 310. It differs from Example 1 by the point which has the surface layer 310c. 15A is a schematic diagram illustrating the configuration of the intermediate transfer belt 310, and FIG. 15B is a schematic cross-sectional view of the intermediate transfer belt 310 when viewed from the moving direction of the intermediate transfer belt 310. It is. The configuration of this example is almost the same as that of Example 1 except that the surface layer 310c is provided. Therefore, in the following description, the same reference numerals are assigned to portions common to the first embodiment, and description thereof is omitted.

  As shown in FIG. 1, the cleaning blade 16 a is pressed against the intermediate transfer belt 310 from the counter direction with respect to the moving direction of the intermediate transfer belt 10. For this reason, when the friction coefficient between the cleaning blade 16a and the pressure contact portion is large, there is a concern that the cleaning blade 16a is turned over or worn due to repeated use. When wear occurs, toner may slip through the worn portion, resulting in poor cleaning.

  Therefore, in this embodiment, as shown in FIGS. 15A and 15B, in order to suppress the occurrence of defective cleaning, the surface of the intermediate transfer belt 310 is moved along the moving direction of the intermediate transfer belt 310. A surface layer 310c (third layer) in which the groove c1 is formed is provided. By providing the surface layer 310c having the groove c1, the contact area between the cleaning blade 16a and the intermediate transfer belt 310 is reduced, and the friction coefficient between the intermediate transfer belt 310 and the cleaning blade 16a can be reduced. As a result, it is possible to improve the cleaning performance in the image forming apparatus 100.

[Description of intermediate transfer belt]
As shown in FIG. 15B, the intermediate transfer belt 310 of this embodiment has a three-layer structure in the thickness direction. The configuration and formation method of the base layer 310a and the inner surface layer 310b are the same as those in the first embodiment. As the colorant added to the inner surface layer 310b, phthalocyanine-based dye pigments, carbon black, carbon nanotubes, and the like can be used. In this example, 10% by mass of carbon black was added, and the surface resistivity of the inner surface layer 310b was 1.0 × 10 ⁶ Ω / □. In addition, since the preferable range of the electrical resistance of the base layer 310a and the inner surface layer 310b of the intermediate transfer belt 310 in the present embodiment is the same as that in the second embodiment, description thereof is omitted.

  The surface layer 310c is a transparent layer having a thickness of about 2 μm in which a resistance adjusting agent and a surface lubricant are added on the outer peripheral surface side of the base layer 310a using an acrylic resin as a base material, and has a light transmittance higher than that of the base layer 310a. Is a high layer. Note that antimony dope is used as the resistance adjusting agent, and polytetrafluoroethylene (hereinafter, PTFE) is used as the surface lubricant. Grooves c1 are periodically formed at predetermined intervals on the surface of the surface layer 310c in the width direction of the intermediate transfer belt 310. As shown in FIG. 15B, the groove c1 is formed by surface processing so that the groove width w1 is 2 μm, the groove depth d is 1 μm, and the groove pitch w2 that is the distance between the grooves is 20 μm. ing.

  The wider the groove pitch w2, the larger the contact area between the cleaning blade 16a and the intermediate transfer belt 310. In this case, the toner remaining on the intermediate transfer belt 310 is difficult to pass through the cleaning blade 16a, while the cleaning blade 16a is likely to be worn at the contact portion between the cleaning blade 16a and the intermediate transfer belt 310. On the other hand, the narrower the groove pitch w2, the smaller the contact area between the cleaning blade 16a and the intermediate transfer belt 310, and the wear of the cleaning blade 16a at the contact portion between the cleaning blade 16a and the intermediate transfer belt 310 is suppressed. In this case, however, the toner remaining on the intermediate transfer belt 310 easily passes through the contact portion between the cleaning blade 16a and the intermediate transfer belt 310, and cleaning failure tends to occur. For the above reasons, in the configuration of the present embodiment, the groove pitch w2 is preferably in the range of 3 μm to 50 μm in consideration of the slipping of the toner remaining on the intermediate transfer belt 310 and the wearability of the cleaning blade 16a.

  When the groove shape is formed on the surface layer 310c as in the intermediate transfer belt 310, the irradiation light emitted from the detection means 40 is reflected also on the side surface of the groove c1. FIG. 16 is a diagram showing a state in which the infrared light irradiated from the detection means 40 is reflected on the intermediate transfer belt of this embodiment. In addition to the regular reflection light and diffuse reflection light described in the first embodiment, in this embodiment, the diffuse reflection light at the groove c1 and the regular reflection light refracted by the surface layer 310c increase, so that the light receiving element 43a receives the light. The reflected light tends to increase.

  FIG. 17A shows the diffuse reflection light from the surface of the intermediate transfer belt and the test patch formed on the intermediate transfer belt detected by the light receiving element 43a when the intermediate transfer belts of the present embodiment and the comparative example 2 are used. It is a result. FIG. 17B shows a ratio obtained by dividing the detection output of the surface of the intermediate transfer belt from the detection output of the test patch in the present example and the comparative example 2 based on the detection result of FIG. , Dynamic range indicator. Note that the intermediate transfer belt of Comparative Example 2 does not have the inner surface layer 310b of the intermediate transfer belt 310 of this embodiment, and has only a layer corresponding to the base layer 310a and the surface layer 310c.

  As shown in FIG. 17A, in the configuration of this example, the detection result of the diffuse reflected light from the surface of the intermediate transfer belt 310 obtained by the light receiving element 43a was 0.5V. This is a result of detecting diffuse reflection light generated in the groove c1 portion of the surface layer 310c and regular reflection light refracted in the groove c1 portion in addition to the diffuse reflection light from the base layer 310a of the intermediate transfer belt 310. As in Example 1, a part of the infrared light emitted from the light emitting element 41a is absorbed by the inner surface layer 310b after passing through the base layer 310a.

  On the other hand, in the configuration of Comparative Example 2, the detection result of the diffuse reflected light from the surface of the intermediate transfer belt was 2.4 V, which was a higher value than that of the present example. This is because, in the configuration of Comparative Example 2, in addition to the diffuse reflection light reflected on the surface of the intermediate transfer belt, the diffuse reflection light generated in the groove portion of the surface layer, and the regular reflection light refracted in the groove portion, the intermediate transfer This is because part of infrared light transmitted through the belt is diffusely reflected on the surface of the support roller 11.

  Further, as shown in FIG. 17A, in the configuration of this example, the detection result of the diffuse reflected light from the test patch obtained by the light receiving element 43a was 2.1V. On the other hand, in the configuration of Comparative Example 2, the detection result of the diffuse reflected light from the test patch was 3.3 V, which was a higher value than that of the present example. This is because, in the configuration of the comparative example 2 that does not have the inner surface layer 310b, in addition to the diffuse reflected light reflected by the test patch, a part of infrared light transmitted through the test patch and the intermediate transfer belt is supported by the support roller. This is because the light is diffusely reflected on the surface 11.

  As shown in FIG. 17B, in the configuration of this example, the value of the dynamic range was 4.4. As a result, in the configuration of this embodiment, the image forming condition can be corrected stably in the same manner as in the first embodiment, regardless of disturbances such as deterioration of the intermediate transfer belt 310 or contamination of each sensor of the detection unit 40. Control can be performed. On the other hand, in the configuration of Comparative Example 2, the value of the dynamic range is 1.7, which is lower than that of the present example. In other words, when the intermediate transfer belt of Comparative Example 2 is used, the dynamic range cannot be secured firmly due to disturbances such as deterioration of the intermediate transfer belt and sensor contamination, and stable correction control of image forming conditions is possible. May not be possible.

  As described above, according to the present embodiment, the inner surface layer 310b is provided even when the groove c1 is formed in the surface layer 310c of the intermediate transfer belt 310 to reduce the dynamic range due to the diffuse reflected light from the surface layer 310c. Thus, the correction control can be performed stably. Therefore, also in the configuration of the present embodiment, the same effects as those of the first to third embodiments can be obtained. Further, it is possible to improve the cleaning property in the image forming apparatus 100 by forming the groove c1 in the surface layer 310c.

  Here, as a means for forming the groove shape on the surface layer 310c of the intermediate transfer belt 310, it is possible to use means such as polishing, cutting and imprinting. In this embodiment, the intermediate transfer belt 310 having the surface layer 310c with the groove c1 can be obtained by appropriately selecting and using a preferable one of these forming means. Among these, from the viewpoint of processing cost and productivity, it is preferable to perform imprint processing utilizing the photocurability of the acrylic resin as the base material of the surface layer 310c. The groove shape may be formed not only by such imprint processing but also by lapping after the acrylic resin is cured.

  In the present embodiment, the configuration in which the plurality of grooves c1 are periodically formed in the width direction of the intermediate transfer belt 310 has been described. However, the present invention is not limited thereto, and the grooves c1 do not necessarily have periodicity. If the groove c1 is formed at least in the region where the infrared light irradiated from the light emitting elements 41a and 41b is applied, the dynamic range due to the diffusely reflected light from the surface layer 310c may be reduced. In such a case, by providing the intermediate transfer belt 310b, the effects described in this embodiment can be sufficiently obtained.

  Further, the groove c <b> 1 may not be formed continuously over the circumference of the intermediate transfer belt 310 in the moving direction of the intermediate transfer belt 310, and may be interrupted in the middle. That is, the groove c <b> 1 may be formed intermittently over the circumference of the intermediate transfer belt 310. Further, the groove c1 only needs to extend along a direction intersecting the width direction orthogonal to the moving direction of the intermediate transfer belt 310, and has an angle with respect to the moving direction of the intermediate transfer belt 310. It may be formed by. However, in order to obtain the effect of reducing the coefficient of friction with the cleaning blade 16a, the angle formed by the direction in which the groove c1 extends with respect to the moving direction of the intermediate transfer belt 310 is preferably 45 ° or less. Preferably it is 10 degrees or less.

  In the first to fourth embodiments, the intermediate transfer type image forming apparatus 100 using the intermediate transfer belt has been described. However, the present invention is not limited to this, and the direct transfer type image forming having the conveyance belt for conveying the transfer material P is performed. Even an apparatus can obtain the above-described effects.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 10 Intermediate transfer belt 10a Surface layer 10b Base layer 40 Detection sensor

Claims (19)

When an image carrier that carries a toner image, a belt that can move in contact with the image carrier, a detection toner image transferred from the image carrier to the belt, and light applied to the belt Detecting means for detecting reflected light from the belt and the detection toner image, and control means for executing correction control of an image forming condition of an image formed by the toner image based on a detection result of the detection means. In an image forming apparatus comprising:
The belt includes a first layer which is the thickest layer among the plurality of layers constituting the belt and to which an ionic conductive agent is added in the thickness direction of the belt, and the first layer. And a second layer having a low light transmittance.   The image forming apparatus according to claim 1, wherein the second layer is a layer formed on an inner peripheral surface side of the belt.   3. The image forming apparatus according to claim 1, wherein the detection unit is disposed opposite to a stretching member that stretches the belt via the belt.   The image forming apparatus according to claim 3, wherein the tension member is a roller made of a metal member.   The belt includes a third layer formed on an outer peripheral surface side of the belt and having a light transmittance higher than that of the first layer, and the third layer includes the image carrier and the third layer. The image forming apparatus according to claim 1, wherein the image forming apparatus is in contact with the image forming apparatus. A cleaning member that contacts the third layer in a counter direction with respect to the moving direction of the belt and collects toner remaining on the belt;
The image forming apparatus according to claim 5, wherein the third layer has a plurality of grooves formed on a surface in contact with the cleaning member.   The image forming apparatus according to claim 6, wherein the groove is periodically formed in a width direction intersecting a moving direction of the belt.   The image forming apparatus according to claim 7, wherein the plurality of grooves are periodically formed at a predetermined interval, and a range of the predetermined interval is 3 μm to 50 μm.   The image according to any one of claims 1 to 8, wherein the belt has a lower surface resistivity measured from the inner peripheral surface side than a surface resistivity measured from the outer peripheral surface side. Forming equipment.   The image forming apparatus according to claim 9, wherein the second layer is a layer to which carbon black is added.   The image forming apparatus according to claim 9, wherein the second layer is a layer to which carbon nanotubes are added.   The image forming apparatus according to claim 1, wherein the second layer is a layer to which a phthalocyanine dye pigment is added. The detection means includes a detection member having a light emitting element that irradiates infrared light toward the belt, and a light receiving element that reflects infrared light reflected from the belt,
The said 2nd layer is formed only in the area | region for one round of the said belt in the position facing the said detection member regarding the moving direction of the said belt. The image forming apparatus described in 1.   The control means detects the reflected light from the belt detected by the light receiving element and the light receiving element when the light emitting element emits infrared light toward the belt and the detection toner image. The image forming apparatus according to claim 13, wherein the correction control is executed based on reflected light from the detection toner image. The detection means includes a first detection member and a second detection member that are disposed on opposite sides of the belt with respect to a width direction orthogonal to the moving direction of the belt.
The first detection member detects regular reflection light from the belt when the light emitting element irradiates infrared light toward the belt and infrared light is irradiated from the light emitting element toward the belt. The image forming apparatus according to claim 1, further comprising: a light receiving element; and a light receiving element that detects diffuse reflection light from the belt.   The second detection member includes a light emitting element that emits infrared light toward the belt, and a light receiving element that detects diffuse reflected light from the belt when infrared light is emitted from the light emitting element toward the belt. The image forming apparatus according to claim 15, further comprising: an element, and no light receiving element that detects regular reflection light from the belt.   The second detection member includes a light emitting element that irradiates infrared light toward the belt, and a light receiving element that detects specularly reflected light from the belt when infrared light is irradiated from the light emitting element toward the belt. The image forming apparatus according to claim 15, further comprising: an element, and no light receiving element that detects diffuse reflected light from the belt.   The belt is an intermediate transfer belt, and the toner image carried on the image carrier is primarily transferred from the image carrier to the intermediate transfer belt and then secondarily transferred from the intermediate transfer belt to a transfer material. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. 18. The belt according to claim 1, wherein the belt is a conveyance belt that conveys a transfer material, and the toner image carried on the image carrier is transferred to a transfer material that is conveyed by the conveyance belt. The image forming apparatus according to claim 1.

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