Recycled paper machine

Abstract

To easily select waste papers.SOLUTION: A waste paper recycling apparatus has a defibrating part to defibrate a waste paper and generate defibrated product, a deposition part to deposit the defibrated product and form a web, a sheet formation part to form a sheet by executing at least either one of heating or compressing of the web, a cutting part to cut the sheet to a predetermined length, and an optical sensor that is disposed on outlet side of the sheet formation part and measures concentration information of the sheet.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a waste paper recycling device.

Background Art

[0002] Conventionally, as shown in Patent Document 1, a waste paper recycling device that defibers waste paper to produce new paper is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above waste paper recycling device, when the recycled paper is repeatedly recycled, the whiteness of the paper tends to gradually decrease, and it may become paper that is not suitable for use. Therefore, it is necessary to determine the pass or fail of the recycled paper. However, when a person determines the paper, there is a problem that the operation efficiency of the waste paper recycling device decreases.

Means for Solving the Problems

[0005] The waste paper recycling device includes a defibering unit that defibers waste paper to generate a defibered material, a deposition unit that deposits the defibered material to form a web, a sheet forming unit that forms a sheet by performing at least one of heating and compressing the web, a cutting unit that cuts the sheet into a predetermined length, and an optical sensor provided on the outlet side of the sheet forming unit that measures the density information of the sheet.

Brief Description of the Drawings

[0006] [Figure 1] Schematic diagram showing the configuration of a sheet manufacturing device. [Figure 2A] Schematic diagram showing the configuration of a detection unit. [Figure 2B] A schematic diagram showing the configuration of the detection unit. [Figure 3] A flowchart illustrating the control method for a sheet manufacturing machine. [Figure 4A] A flowchart illustrating the control method for a sheet manufacturing machine. [Figure 4B] A flowchart illustrating the control method for a sheet manufacturing machine. [Figure 4C] A flowchart illustrating the control method for a sheet manufacturing machine. [Figure 4D] A diagram showing an example of the relationship between AD value and whiteness. [Figure 5A] A flowchart illustrating the control method for a sheet manufacturing machine. [Figure 5B] A flowchart illustrating the control method for a sheet manufacturing machine. [Figure 5C] A diagram showing an example of sheet identification. [Modes for carrying out the invention]

[0007] First, let's describe the configuration of the sheet manufacturing apparatus 1 as a waste paper recycling device. The sheet manufacturing apparatus 1 is suitable for producing new paper (sheet S) by, for example, dry defibrating used waste paper as raw material, then compressing (pressuring), heating, and cutting it. By mixing various additives with the fibrous raw material, the bonding strength and whiteness of the sheet S can be improved, or functions such as color, scent, and flame retardancy can be added, depending on the application. Furthermore, by controlling the density, thickness, and shape of the sheet S, it is possible to produce sheets S of various thicknesses and sizes to suit different applications, such as A4 and A3 office paper and business card paper.

[0008] As shown in Figure 1, the sheet manufacturing apparatus 1 comprises a supply unit 10, a crushing unit 12, a defibration unit 20, a sorting unit 40, a first web forming unit 45, a rotating body 49, a mixing unit 50, a stacking unit 60, a conveying unit 79, a sheet forming unit 80, a cutting unit 90, and a detection unit 100.

[0009] Furthermore, the sheet manufacturing apparatus 1 includes a control unit 300 that controls the above-mentioned parts. The control unit 300 includes a CPU, memory, control circuit, I / F (interface), etc. The CPU is an arithmetic processing unit. The memory is a storage device that reserves an area for storing various programs and parameters of the CPU or a working area, and has memory elements such as RAM and EEPROM. The I / F is configured to send and receive information with an external device such as an information processing terminal. The control unit 300 executes arithmetic processing on the CPU according to various programs, etc., and controls each drive unit, etc. via the control circuit.

[0010] Furthermore, the sheet manufacturing apparatus 1 includes humidification units 202, 204, 206, 208, 210, and 212 for purposes such as humidifying the raw materials and humidifying the space in which the raw materials move. Humidification suppresses the adhesion of raw materials due to static electricity. Humidification units 202, 204, 206, and 208 are composed of, for example, evaporative or hot air evaporative humidifiers. Humidification units 210 and 212 are composed of, for example, ultrasonic humidifiers.

[0011] The supply unit 10 supplies raw materials to the crushing unit 12. The raw materials supplied to the crushing unit 12 can be anything containing fibers, such as paper, pulp, pulp sheets, nonwoven fabrics, cloth, or textiles. Below, we will illustrate a configuration in which the sheet manufacturing apparatus 1 uses recycled paper as raw material. The supply unit 10 includes, for example, a stacker for stacking and accumulating recycled paper, and an automatic feeding device for sending the recycled paper from the stacker to the crushing unit 12.

[0012] The coarse crushing unit 12 cuts the raw material supplied by the supply unit 10 with coarse crushing blades 14 to produce coarse fragments. The coarse crushing blades 14 cut the raw material in air, such as in the atmosphere. The coarse crushing unit 12 can have a configuration similar to a so-called shredder, for example, having a pair of coarse crushing blades 14 that cut the raw material and a drive unit that rotates the coarse crushing blades 14. The shape and size of the coarse fragments are arbitrary, as long as they are suitable for the defibration process in the defibration unit 20. The coarse crushing unit 12 cuts the raw material into paper pieces of a size of, for example, 1 cm to several cm square or smaller. The coarse fragments cut by the coarse crushing unit 12 are transported to the defibration unit 20 via the chute 9 and through the pipe 2.

[0013] The defibration unit 20 defibrates the coarsely crushed material cut in the coarse crushing unit 12. Specifically, the defibration unit 20 defibrates the raw material cut by the coarse crushing unit 12 to produce defibrated material. Here, "defibration" means separating the raw material, which is made up of multiple fibers bound together, into individual fibers. The defibration unit 20 has the function of separating substances such as resin particles, ink, toner, and anti-bleeding agents attached to the raw material from the fibers.

[0014] The material that passes through the defibration section 20 is called defibrated material. In addition to the unraveled defibrated fibers, the defibrated material may also contain resin particles separated from the fibers during the unraveling process, i.e., resin particles that bind multiple fibers together, as well as colorants such as ink and toner, and additives such as anti-bleeding agents and paper strength enhancers. The shape of the unraveled defibrated material is string-like or flat string-like. The unraveled defibrated material may exist in an independent state, that is, not entangled with other unraveled fibers, or it may exist in a clump-like state, that is, entangled with other unraveled defibrated material, forming a mass.

[0015] The defibration unit 20 performs defibration in a dry manner. Here, processing such as defibration in an air environment, such as the atmosphere, rather than in a liquid is referred to as a dry method. The defibration unit 20 is constructed, for example, using an impeller mill. Specifically, the defibration unit 20 has a high-speed rotating rotor and a liner located on the outer circumference of the rotor. The coarsely crushed pieces cut in the coarse crushing unit 12 are sandwiched between the rotor and the liner of the defibration unit 20 and defibrated. The defibration unit 20 generates an airflow by the rotation of the rotor. This airflow allows the defibration unit 20 to suck the coarsely crushed pieces, which are the raw material, from the pipe 2 through the inlet 22 and transport the defibrated material to the outlet 24. The defibrated material is sent from the outlet 24 to the pipe 3 and transported through the pipe 3 to the sorting unit 40. In this embodiment, the sheet manufacturing apparatus 1 is equipped with a defibration blower 26, which is an airflow generating device, and the defibrated material is conveyed to the sorting section 40 by the airflow generated by the defibration blower 26.

[0016] The sorting section 40 is provided with an inlet 42 through which the fiberized material fiberized by the fiberizing section 20 from the pipe 3 flows in together with the air current. The sorting section 40 sorts the fiberized material introduced from the inlet 42 according to the length of the fibers. Specifically, the sorting section 40 regards the fiberized material with a size less than a predetermined size among the fiberized material fiberized by the fiberizing section 20 as the first sorted material, and sorts the fiberized material larger than the first sorted material as the second sorted material. The first sorted material contains fibers or particles, etc., and the second sorted material contains, for example, large fibers, unfiberized pieces, crushed pieces that have not been sufficiently fiberized, lumps in which the fiberized fibers are aggregated or entangled, etc.

[0017] The sorting section 40 has, for example, a drum section 41 and a housing section 43 that houses the drum section 41.

[0018] The drum section 41 is a cylindrical sieve that is rotationally driven by a motor. The drum section 41 has a net and functions as a sieve. Through the mesh of this net, the drum section 41 sorts the fiberized material into a first sorted material smaller than the mesh opening size of the net and a second sorted material larger than the mesh opening. As the net of the drum section 41, for example, a wire mesh, an expanded metal obtained by stretching a perforated metal plate, or a punching metal in which holes are formed in a metal plate using a press or the like can be used.

[0019] The fiberized material introduced from the inlet 42 is sent into the drum section 41 together with the air current, and the first sorted material falls downward from the mesh of the drum section 41 due to the rotation of the drum section 41. The second sorted material that cannot pass through the mesh of the drum section 41 is carried by the air current flowing from the inlet 42 into the drum section 41 and guided to the discharge port 44, and sent out to the pipe 8. The pipe 8 connects the inside of the drum section 41 and the pipe 2. The second sorted material flowing through the pipe 8 is returned to the fiberizing section 20 and fiberized.

[0020] The first sorted material sorted by the drum section 41 disperses into the air through the mesh of the drum section 41 and descends toward the mesh belt 46 of the first web forming section 45 located below the drum section 41.

[0021] The first web forming section 45 includes a mesh belt 46, rollers 47, and a suction section 48. The mesh belt 46 is an endless belt suspended by three rollers 47 and rotates due to the movement of the rollers 47. The surface of the mesh belt 46 is made up of a mesh with openings of a predetermined size. Of the first sorted material descending from the sorting section 40, fine particles that are small enough to pass through the mesh fall below the mesh belt 46, while fibers that are too small to pass through the mesh accumulate on the mesh belt 46 and are conveyed together with the mesh belt 46 in the direction of the arrow. The fine particles that fall from the mesh belt 46 are relatively small or low-density materials from the defibrated material (first sorted material), that is, resin particles, colorants, and additives that are unnecessary for fiber bonding, and are removed materials that the sheet manufacturing apparatus 1 does not use in the manufacture of the sheet S.

[0022] The mesh belt 46 moves at a constant speed V1 during normal operation to manufacture the sheet S. Here, "normal operation" refers to operation excluding the execution of start control and stop control of the sheet manufacturing apparatus 1, and more specifically, while the sheet manufacturing apparatus 1 is manufacturing a sheet S of the desired quality.

[0023] The suction unit 48 draws air from below the mesh belt 46. The suction unit 48 is connected to the dust collection unit 27 via the pipe 23. The dust collection unit 27 is a filter-type or cyclone-type dust collector that separates fine particles from the airflow. A collection blower 28 is installed downstream of the dust collection unit 27, and the collection blower 28 functions as a dust collection suction unit that draws air from the dust collection unit 27. The air discharged by the collection blower 28 is then discharged outside the sheet manufacturing apparatus 1 via the pipe 29.

[0024] In the conveying path of the mesh belt 46, air containing mist is supplied downstream of the sorting section 40 by the humidification section 210. The mist, which is fine water particles generated by the humidification section 210, descends toward the first web W1, supplying moisture to the first web W1. This adjusts the amount of moisture contained in the first web W1, thereby suppressing the adsorption of fibers onto the mesh belt 46 due to static electricity.

[0025] The sheet manufacturing apparatus 1 has a rotating body 49 that divides the first web W1 accumulated on the mesh belt 46. The first web W1 is separated from the mesh belt 46 at the position where the mesh belt 46 is folded back by the rollers 47 and then divided by the rotating body 49.

[0026] The rotating body 49 has a rotating blade shape with plate-shaped blades that rotate. The rotating body 49 is positioned where the blades come into contact with the first web W1 that separates from the mesh belt 46. By rotating the rotating body 49, for example in the direction indicated by arrow R in the figure, the first web W1 that separates from the mesh belt 46 and is conveyed collides with the blades and is divided, generating fragments P. The fragments P divided by the rotating body 49 descend inside the pipe 7 and are conveyed to the mixing section 50 by the airflow flowing inside the pipe 7.

[0027] The mixing unit 50 includes an additive supply unit 52 for supplying additives containing resin, a pipe 54 communicating with the pipe 7 and through which an airflow containing the subdivided material P flows, and a mixing blower 56. The mixing unit 50 mixes the additives containing resin with the fibers constituting the subdivided material P.

[0028] In the mixing section 50, an airflow is generated by the mixing blower 56, and the subdivided material P and the additive are mixed and conveyed within the pipe 54. Furthermore, as the subdivided material P flows through the inside of the pipes 7 and 54, it is broken down into finer fibers.

[0029] The additive supply unit 52 is connected to an additive cartridge (not shown) that stores additives and supplies the additives from inside the additive cartridge to the pipe 54. The additive supply unit 52 stores the additives, which consist of fine powder or fine particles, from inside the additive cartridge. The additive supply unit 52 has a discharge unit 52a that sends the stored additives to the pipe 54.

[0030] The additive supplied by the additive supply unit 52 includes a resin for binding multiple fibers together. The resins included in the additive are thermoplastic resins and thermosetting resins, such as AS resin, ABS resin, polypropylene, polyethylene, polyvinyl chloride, polystyrene, acrylic resin, polyester resin, polyethylene terephthalate, polyphenylene ether, polybutylene terephthalate, polyamide, polycarbonate, polyacetal, polyphenylene sulfide, polyether ether ketone, etc. These resins may be used individually or in appropriate mixtures. That is, the additive may contain a single substance or a mixture, and may contain multiple types of particles, each composed of one or more substances. Furthermore, the additive may be in fibrous form or in powder form.

[0031] The resin contained in the additive melts when heated, binding multiple fibers together. Therefore, if the resin is mixed with the fibers but not heated to the temperature at which the resin melts, the fibers will not bind together.

[0032] The airflow generated by the mixing blower 56 draws the subdivided material P descending through the pipe 7, and the additive supplied by the additive supply unit 52, into the inside of the pipe 54 and passes through the inside of the mixing blower 56. The airflow generated by the mixing blower 56 and the action of the rotating parts of the mixing blower 56, such as the blades, mix the fibers constituting the subdivided material P with the additive, and this mixture, i.e., the mixture of the first sorted material and the additive, is transported through the pipe 54 to the accumulation unit 60.

[0033] The deposition section 60 includes a second web-forming section 70. The mixture of the first sorted material and additives that has passed through the mixing section 50 is introduced through the inlet 62, and the entangled defibrated material (first sorted material) is loosened and dispersed in the air as it falls. Furthermore, if the resin of the additive supplied from the additive supply section 52 is fibrous, the deposition section 60 loosens the entangled resin. As a result, the deposition section 60 can deposit the mixture uniformly into the second web-forming section 70.

[0034] The deposition section 60 includes a drum section 61 and a housing section 63 that houses the drum section 61. The drum section 61 is a cylindrical sieve that is rotationally driven by a motor. The drum section 61 has a mesh and functions as a sieve. Due to the mesh, the drum section 61 allows fibers and particles with smaller mesh openings to pass through and descend from the drum section 61. The configuration of the drum section 61 is, for example, the same as the configuration of the drum section 41.

[0035] A second web-forming section 70 is positioned below the drum section 61. The second web-forming section 70 deposits the material that has passed through the deposit section 60 to form a second web W2 (corresponding to a web). The second web-forming section 70 includes, for example, a mesh belt 72, a roller 74, and a suction mechanism 76.

[0036] The mesh belt 72 is an endless belt suspended by a plurality of rollers 74, and rotates as the rollers 74 move. The mesh belt 72 can be made of, for example, metal, resin, cloth, or nonwoven fabric. The surface of the mesh belt 72 is made of a mesh with openings of a predetermined size. Of the fibers and particles falling from the drum section 61, fine particles that are small enough to pass through the mesh fall to the bottom of the mesh belt 72, while fibers that are too small to pass through the mesh accumulate on the mesh belt 72 and are conveyed together with the mesh belt 72 in the direction of the arrow. During normal operation to manufacture the sheet S, the mesh belt 72 moves at a constant speed V2.

[0037] The mesh of the mesh belt 72 is fine enough to prevent most of the fibers and particles descending from the drum section 61 from passing through.

[0038] The suction mechanism 76 is located below the mesh belt 72. The suction mechanism 76 is equipped with a suction blower 77, and the suction force of the suction blower 77 can generate a downward airflow in the suction mechanism 76.

[0039] The suction mechanism 76 draws the mixture dispersed in the air by the deposition section 60 onto the mesh belt 72. This promotes the formation of the second web W2 on the mesh belt 72 and increases the discharge rate from the deposition section 60. Furthermore, the suction mechanism 76 can create a downflow in the mixture's fall path, preventing entanglement of defibrated material and additives during the fall.

[0040] As described above, by passing through the deposition section 60, a second web W2 is formed that contains a lot of air and is soft and swollen. The second web W2 deposited on the mesh belt 72 is transported to the sheet forming section 80.

[0041] In the conveying path of the mesh belt 72, air containing mist is supplied to the downstream side of the accumulation section 60 by the humidification section 212. As a result, the mist generated by the humidification section 212 is supplied to the second web W2, and the amount of moisture contained in the second web W2 is adjusted. This suppresses the adsorption of fibers onto the mesh belt 72 due to static electricity.

[0042] The sheet manufacturing apparatus 1 has a conveying unit 79 that conveys the second web W2 on the mesh belt 72 to the sheet forming unit 80. The conveying unit 79 includes, for example, a mesh belt 79a, a roller 79b, and a suction mechanism 79c.

[0043] The suction mechanism 79c includes a blower (not shown) that generates an upward airflow on the mesh belt 79a by the suction force of the blower. This airflow attracts the second web W2, causing the second web W2 to separate from the mesh belt 72 and be attracted to the mesh belt 79a. The mesh belt 79a moves due to the rotation of the rollers 79b, transporting the second web W2 to the sheet forming section 80.

[0044] In this manner, the conveying unit 79 peels the second web W2 formed on the mesh belt 72 from the mesh belt 72 and conveys it.

[0045] The sheet forming unit 80 forms a sheet S by heating and / or compressing (pressurizing) the second web W2. In this embodiment, the sheet forming unit 80 forms a sheet S by pressurizing and heating the second web W2, which is deposited on the mesh belt 72 and transported by the transport unit 79. In the sheet forming unit 80, heat is applied to the fibers and additives contained in the second web W2, thereby binding multiple fibers in the mixture to each other via the resin.

[0046] The sheet forming section 80 includes a pressurizing section 82 for pressurizing the second web W2, and a heating section 84 for heating the second web W2 that has been pressurized by the pressurizing section 82.

[0047] The pressurizing section 82 consists of a pair of calender rollers 85, which pressurize the second web W2 by clamping it with a predetermined nip pressure. The second web W2 becomes thinner due to the pressurization, and its density is increased. One of the pair of calender rollers 85 is a driven roller driven by a motor (not shown), and the other is a driven roller. The calender rollers 85 rotate due to the driving force of the motor, and convey the second web W2, which has become denser due to the pressurization, toward the heating section 84.

[0048] The heating section 84 is composed of, for example, heating rollers, a hot press molding machine, a hot plate, a hot air blower, an infrared heater, a flash fuser, and the like. In this embodiment, the heating section 84 includes a pair of heating rollers 86. The heating rollers 86 are heated to a preset temperature by a heater installed inside or outside. The heating rollers 86 apply heat to the second web W2, which is pressurized by the calender roller 85, to form the sheet S.

[0049] One of the pair of heating rollers 86 is a driven roller driven by a motor (not shown), and the other is a driven roller. The heating rollers 86 rotate due to the driving force of the motor and convey the heated sheet S toward the cutting section 90.

[0050] The cutting section 90 cuts the sheet S formed by the sheet forming section 80 to a predetermined length. The cutting section 90 in this embodiment has a first cutting section 92 that cuts the sheet S in a direction intersecting the conveying direction of the sheet S, and a second cutting section 94 that cuts the sheet S in a direction parallel to the conveying direction. The second cutting section 94 cuts the sheet S that has passed through the first cutting section 92, for example. This forms single sheets of a predetermined size. The cut single sheets of sheet S are discharged to the discharge section 96. The discharge section 96 includes a first discharge section 96a and a second discharge section 96b on which sheets S can be placed. The first discharge section 96a and the second discharge section 96b are trays or stackers.

[0051] Furthermore, the sheet manufacturing apparatus 1 is equipped with a detection unit 100 on the outlet side (downstream side) of the sheet forming unit 80. The detection unit 100 is configured to measure the concentration information of the sheet S. The detailed configuration of the detection unit 100 will be described later. The control unit 300 determines whether a sheet S is acceptable or unacceptable based on the concentration information of the sheet S measured by the detection unit 100. For example, a sheet Sa determined to be acceptable (good) is discharged to the first discharge unit 96a, and a sheet Sb determined to be unacceptable (defective) is discharged to the second discharge unit 96b. By mechanizing the identification of sheet S, the identification process is streamlined, improving the operational efficiency of the sheet manufacturing apparatus 1. In other words, sheet S can be easily identified while keeping labor costs down.

[0052] Next, the configuration of the detection unit 100 will be described. As shown in Figures 2A and 2B, the detection unit 100 includes an optical sensor 110 and a reference member 120. The optical sensor 110 measures the density information of the sheet S formed by the sheet forming unit 80. The density information of the sheet S includes, for example, the density of each RGB color component of the sheet S's color and the RGB color difference of the sheet S. The optical sensor 110 is located on the outlet side (downstream side) of the sheet forming unit 80. In this embodiment, the optical sensor 110 is located between the sheet forming unit 80 and the cutting unit 90 in the sheet S transport path. Alternatively, the optical sensor 110 may be located between the cutting unit 90 and the discharge unit 96. The optical sensor 110 can be positioned according to the layout of each part of the sheet manufacturing apparatus 1.

[0053] The optical sensor 110 has a light-emitting unit 111 that can emit light and an RGB sensor 112 that can receive light. The light-emitting unit 111 is, for example, a white LED (Light Emitting Diode) that emits light toward the sheet S. The RGB sensor 112 has three color sensors that can receive red, green, and blue wavelengths and receives the reflected light reflected from the sheet S. Each color sensor of the RGB sensor 112 acquires a voltage value proportional to the amount of light received. Based on each voltage value, it is possible to acquire the density of each RGB color component of the sheet S's color and the RGB color difference of the sheet S. This makes it possible to reliably determine whether the sheet S is acceptable or not based on its density (whiteness) and color difference. Furthermore, by individually setting the specifications for the density (whiteness) and color difference of the sheet S, the user can determine the quality of the sheet S they desire.

[0054] In this embodiment, the optical sensor 110 is positioned above the sheet S being transported, and the light-emitting unit 111 and the RGB sensor 112 are positioned facing the upper surface S1 of the sheet S. That is, the light-emitting surface of the light-emitting unit 111 and the light-receiving surface of the RGB sensor 112 face downward, so that foreign matter such as paper dust adheres to the light-emitting unit 111 and the RGB sensor 112, and accurate measurements can be performed.

[0055] The reference member 120 is a component used for calibration of the optical sensor 110, and is used, for example, to adjust the sensitivity of the RGB sensor 112 in the optical sensor 110. The reference member 120 is positioned opposite the optical sensor 110. In this embodiment, the reference member 120 is positioned below the optical sensor 110, and during the operation of the sheet manufacturing apparatus 1, the optical sensor 110 and the reference member 120 are positioned opposite each other with the conveyed sheet S in between.

[0056] The reference member 120 includes a reference color section 121. The reference color section 121 is provided on a flat surface of the reference member 120 that can face the optical sensor 110. The reference color section 121 is a formed film on which a reference color (color and density) having a constant reflectance to the light emitted by the light-emitting section 111 is printed. When the optical sensor 110 is calibrated, the sensitivity of the RGB sensor 112 is adjusted by adjusting the illuminance of the light-emitting section 111 based on the voltage value (AD value) obtained from the light emitted by the light-emitting section 111 to the reference color section 121 and the light received by the RGB sensor 112. This allows the performance of the optical sensor 110 to be maintained. It also suppresses individual variations in the optical sensor 110. Furthermore, it allows for the determination of the quality of the mounting condition of the optical sensor 110. Furthermore, the reference color section 121 can appropriately set a reference color (color and density) for defining the pass / fail judgment of the formed sheet S. That is, the reference color (color and density) can be set to the reflectance that serves as the threshold for determining the pass / fail judgment of the sheet S. This allows the user to determine the sheet S with the desired density (whiteness) and color difference.

[0057] The reference member 120 is held so as to be rotatable. The reference member 120 is equipped with a rotation shaft 125. The rotation shaft 125 rotates due to the driving force of the motor, and the entire reference member 120 rotates in conjunction with the rotation of the rotation shaft 125. Specifically, the reference member 120 rotates between a first state CD1 (Figure 2A) in which the reference color section 121 faces the optical sensor 110 (light-emitting section 111, RGB sensor 112) when the optical sensor 110 is being calibrated, and a second state CD2 (Figure 2B) in which the reference color section 121 faces away from the optical sensor 110 during the period when the sheet manufacturing apparatus 1 is in operation. The control unit 300 displaces the reference member 120 to the first state CD1 or the second state CD2 by driving and controlling the rotation direction of the motor.

[0058] Furthermore, the detection unit 100 includes a photointerrupter 127 for determining the presence or absence of a first state CD1 (second state CD2) of the reference member 120. The photointerrupter 127 has an opposing light-emitting part and a light-receiving part, and is a sensor that determines the presence or absence of an object by detecting that an object is blocking the light from the light-emitting part with the light-receiving part. A projection 126 is formed on a part of the reference member 120. The reference member 120 rotates, and the light receiving unit detects that the projection 126 is blocking the light from the light-emitting part of the photointerrupter 127, thereby determining that the reference member 120 is in the first state CD1 (not the second state CD2). At this point, when the projection 126 is detected by the photointerrupter 127, the positions of the projection 126 and the photointerrupter 127 are set so that the reference color part 121 faces the optical sensor 110. Alternatively, photointerrupters 127 may be placed on both sides of the reference member 120 to enable detection of the first state CD1 and the second state CD2 of the reference member 120.

[0059] In the first state CD1, the optical sensor 110 (light-emitting part 111, RGB sensor 112) and the reference color part 121 face each other, allowing the optical sensor 110 to be calibrated. On the other hand, in the second state CD2, the reference color part 121 faces downwards, which suppresses the adhesion of foreign matter such as paper dust to the reference color part 121. Furthermore, the reference member 120 can be easily displaced between the first state CD1 and the second state CD2 by driving the rotating shaft 125. In addition, no space is required for the reference member 120 to displace between the first state CD1 and the second state CD2, which helps to suppress the increase in size of the sheet manufacturing apparatus 1.

[0060] Furthermore, when the reference color section 121 faces the optical sensor 110 (first state CD1), the distance D1 between the surface of the reference color section 121 and the optical sensor 110 is equal to the distance D2 between the sheet S being transported and the optical sensor 110 when the reference member 120 is in the second state CD2 and the sheet manufacturing apparatus 1 is in operation. As a result, the calibration of the optical sensor 110 is performed under the same conditions as when measuring the density information of the formed sheet S, so that the density information of the sheet S can be measured accurately.

[0061] Next, the control method for the sheet manufacturing apparatus 1 will be described. In this embodiment, the control method for the detection unit 100 will be described. As shown in Figure 3, in the sheet manufacturing apparatus 1, first, a calibration process for the optical sensor 110 is performed (step S100). The control unit 300 controls the optical sensor 110 and the reference member 120 to adjust the sensitivity of the optical sensor 110 (RGB sensor 112). Next, the sheet S formation process is performed (step S200). The control unit 300 controls the supply unit 10, etc., to form the sheet S. Next, a discrimination process for the formed sheet S is performed (step S300). Based on the density information of the sheet S acquired by the optical sensor 110, the control unit 300 determines whether the sheet S is acceptable or not, and sorts them into acceptable (good) sheet Sa and unacceptable (defective) sheet Sb. Note that the calibration process may be performed while the sheet S formation process is in progress. That is, the calibration process for the optical sensor 110 may be performed before the sheet S is transported to the detection unit 100. Alternatively, the discrimination process for the sheet S may be performed while the sheet S formation process is in progress. In this way, the sheet manufacturing apparatus 1 can be operated efficiently. The following describes each process. Note that the sheet formation process (step S200) is the same as described in the configuration of the sheet manufacturing apparatus 1, so the explanation is omitted.

[0062] Figures 4A, 4B, 4C, and 4D show the contents of the calibration process (step S100) of the optical sensor 110. First, the control unit 300 acquires the AD values ​​of the RGB sensors 112 (each color sensor) when the light-emitting unit 111 is not emitting light, and determines whether or not there is an abnormality in the initial stage of the RGB sensors 112. Specifically, in step S101, the control unit 300 sets the reference member 120 to the first state CD1. For example, if the reference member 120 is in the second state CD2, the control unit 300 rotates the rotation shaft 125 so that the reference member 120 is in the first state CD1.

[0063] Next, in step S102, the control unit 300 determines whether the reference member 120 is in the first state CD1 (Figure 2A). Specifically, it determines whether the photointerrupter 127 has detected the projection 126. If it is determined that the reference member 120 is in the first state CD1 (YES), the process proceeds to step S103. On the other hand, if it is determined that the reference member 120 is not in the first state CD1 (NO), the process proceeds to step S106.

[0064] If the process proceeds to step S106, the control unit 300 determines whether the number of times the reference member 120 has been determined not to be in the first state CD1 is a predetermined number. The predetermined number is, for example, the second time. In this case, if the number of times the reference member 120 has been determined not to be in the first state CD1 is the first time (NO), the process proceeds to step S101. On the other hand, if the number of times the reference member 120 has been determined not to be in the first state CD1 is the second time (YES), the process proceeds to step S107. In step S107, error processing is performed. For example, if the reference member 120 cannot be set to the first state CD1, an error in the photointerrupter 127, a mounting problem with the reference member 120, a motor malfunction, or other errors can be inferred.

[0065] If the process proceeds to step S103, the control unit 300 drives only the RGB sensor 112 while keeping the light-emitting unit 111 off. The voltage values ​​acquired by the RGB sensor 112 are then digitally converted to obtain the AD values ​​of each color sensor.

[0066] Next, in step S104, the control unit 300 determines whether the acquired AD value is below a predetermined value. The predetermined value is the abnormality detection threshold for the AD value when the light-emitting unit 111 is not emitting light. When the light-emitting unit 111 is not emitting light, the amount of light received from the reference color unit 121 is less than when the light-emitting unit 111 is emitting light. Therefore, if the AD value of each color sensor is low (below the abnormality detection threshold), the control unit 300 determines that it is normal (YES) and proceeds to step S105, where the AD value of each color sensor when the light-emitting unit 111 is not emitting light is stored in memory. On the other hand, if the AD value is greater than the abnormality detection threshold (NO), the process proceeds to step S107. In step S107, abnormality processing is performed. In this case, it is presumed that there is an abnormality in the RGB sensor 112 itself.

[0067] Next, the control unit 300 acquires the AD values ​​of the RGB sensors 112 (each color sensor) when the light-emitting unit 111 is emitting light, and adjusts the sensitivity of the RGB sensors 112. Specifically, in step S108, the control unit 300 causes the light-emitting unit 111 to emit light using the initially set initial light emission value parameter.

[0068] Next, in step S109, after the light emission amount of the light emission unit 111 has stabilized, the control unit 300 acquires the AD value of the color sensor with the highest sensitivity or the lowest sensitivity among the color sensors of the RGB sensor 112. In this embodiment, the AD value of the R (red) color sensor with the highest sensitivity is acquired. By acquiring the AD value of the color sensor with the highest sensitivity or the lowest sensitivity, the illuminance of the light emission unit 111 can be adjusted efficiently.

[0069] Next, in step S110, the control unit 300 determines whether the acquired AD value is within a predetermined range. Specifically, it determines whether the AD value acquired by the initial light emission value parameter is above the lower limit of the abnormality determination threshold and below the upper limit of the abnormality determination threshold. In other words, it determines whether the color sensor is pass or fail in its initial state. If it is determined that the acquired AD value is within the predetermined range (YES), the process proceeds to step S111. On the other hand, if it is determined that the acquired AD value is not within the predetermined range (NO), the process proceeds to step S117, where the optical sensor 110 is determined to be abnormal and abnormal processing is executed.

[0070] Next, in step S111, the control unit 300 calculates the ratio between the AD value acquired in step S109 (in this embodiment, the R (red) color sensor) and the target AD value of that color sensor. This calculates the difference (ratio) between the AD value in the initial state and the target AD value.

[0071] Next, in step S112, the control unit 300 reflects the ratio calculated in step S111 in the light emission value parameter of the light emission unit 111. For example, if the ratio of the initial AD value to the target AD value is 1:2, the light emission value parameter of the light emission unit 111 is changed to a new parameter corresponding to twice the initial light emission value parameter. In this example, the amount of light emitted from the light emission unit 111 is adjusted in the direction of increasing the amount of light emitted (in the direction of becoming brighter). This adjusts the sensitivity of the optical sensor 110, making it possible to obtain the AD value of the color sensor corresponding to the target value. Then, the light emission unit 111 is made to emit light using the adjusted light emission value parameter.

[0072] Next, in step S113, after the amount of light emitted from the light-emitting unit 111 has stabilized, the control unit 300 acquires the AD value of the color sensor with the highest sensitivity or the lowest sensitivity among the color sensors of the RGB sensor 112. In this embodiment, the AD value of the R (red) color sensor with the highest sensitivity is acquired.

[0073] Next, in step S114, the control unit 300 determines whether the acquired AD value is within the range of the target value. Specifically, it determines whether the acquired AD value is within the acceptable range of the target value set in step S111. Then, if it is determined that the acquired AD value is within the range of the target value (YES), the process proceeds to step S115. In step S115, the control unit 300 stores the adjusted light emission value parameters in memory. On the other hand, if it is determined that the acquired AD value is not within the range of the target value (NO), the process proceeds to step S116. In step S116, the control unit 300 determines whether the number of times the acquired AD value has been determined to be outside the range of the target value is less than or equal to a predetermined number. If it is determined to be less than or equal to the predetermined number (YES), the process proceeds to step S111. On the other hand, if it is determined to be more than or equal to the predetermined number (NO), the process proceeds to step S117, where the optical sensor 110 is determined to be abnormal and abnormal processing is executed.

[0074] Next, the control unit 300 acquires the AD value of the RGB sensor 112 after sensitivity adjustment and calculates a relationship (proportional equation) between density (whiteness) and AD value. Specifically, in step S118, the control unit 300 causes the light-emitting unit 111 to emit light using the adjusted light emission value parameters stored in memory, and after the amount of light emitted by the light-emitting unit 111 stabilizes, it acquires the AD values ​​of each color sensor in the RGB sensor 112.

[0075] Next, in step S119, the control unit 300 stores the acquired AD values ​​of each color sensor in memory.

[0076] Next, in step S120, the control unit 300 calculates a proportional equation (linear equation) using the AD values ​​of each color sensor acquired when the light-emitting unit 111 is not emitting light (step S105) and the AD values ​​of each color sensor acquired when the light-emitting unit 111 is emitting light (step S115). As a result, as shown in Figure 4D, a relationship equation (proportional equation) between density (whiteness) and AD value is calculated for each color sensor.

[0077] Next, in step S121, the control unit 300 stores the calculated proportional formulas for each color sensor in the RGB sensor 112 into memory. With the above steps, the calibration process for the optical sensor 110 is completed.

[0078] Next, the sheet S discrimination process (step S300) will be described. Figures 5A, 5B, and 5C show the contents of the sheet S discrimination process. First, the control unit 300 performs the sheet S formation process and determines whether the formed sheet S has reached the measurable area of ​​the optical sensor 110. Specifically, in step S301, the control unit 300 causes the reference member 120 to be set to the second state CD2. For example, if the reference member 120 is in the first state CD1, the rotation shaft 125 is rotated so that the reference member 120 is in the second state CD2.

[0079] Next, in step S302, the control unit 300 determines whether the reference member 120 is in the second state CD2 (Figure 2B). Specifically, it determines whether the protrusion 126 on the photointerrupter 127 has been detected. If it is determined that the reference member 120 is in the second state CD2 (YES), the process proceeds to step S303. On the other hand, if it is determined that the reference member 120 is not in the second state CD2 (NO), the process proceeds to step S307.

[0080] If the process proceeds to step S307, the control unit 300 determines whether the number of times the reference member 120 has been determined not to be in the second state CD2 is a predetermined number. The predetermined number is, for example, the second time. In this case, if the number of times the reference member 120 has been determined not to be in the second state CD2 is the first time (NO), the process proceeds to step S301. On the other hand, if the number of times the reference member 120 has been determined not to be in the second state CD2 is the second time (YES), the process proceeds to step S308. In step S308, error processing is performed. For example, if the reference member 120 cannot be set to the second state CD2, an error such as a malfunction of the photointerrupter 127, a mounting problem with the reference member 120, or a motor malfunction can be inferred.

[0081] In step S303, the control unit 300 determines whether or not the sheet S formed in the measurable area of ​​the optical sensor 110 has been transported. For example, the light-emitting part 111 of the optical sensor 110 emits light, and the RGB sensor 112 receives the reflected light. Since the amount of light received changes depending on whether or not there is reflection from the sheet S, it is possible to detect whether or not the sheet S has been transported. If it is determined that the sheet S has been transported (YES), the process proceeds to step S304. On the other hand, if it is determined that the sheet S has not been transported (NO), the process proceeds to step S302.

[0082] Next, in step S304, the control unit 300 acquires the AD values ​​of the RGB sensor 112 at a predetermined period (for example, 1 msec). Specifically, it acquires the AD values ​​of each color sensor. The predetermined period can be set as appropriate according to the transport speed of the sheet S.

[0083] Next, in step S305, the control unit 300 averages the acquired AD values ​​of each color sensor. Specifically, it calculates the average value of a predetermined number of AD values ​​acquired sequentially from each color sensor.

[0084] Next, in step S306, the control unit 300 determines whether the average value of the AD values ​​of each color sensor calculated in step S305 is equal to or greater than a specified value. The specified value is a threshold value for determining the presence or absence of the sheet S in the measurable area of ​​the optical sensor 110. If it is determined that the average value of the AD values ​​of each color sensor is equal to or greater than the specified value (YES), that is, if the sheet S has reached the measurable area of ​​the optical sensor 110, the process proceeds to step S309. On the other hand, if it is determined that the average value of the AD values ​​of each color sensor is not equal to or greater than the specified value (NO), the process proceeds to step S305.

[0085] From step S309 onward, the control unit 300 calculates the RGB density and RGB color difference of the sheet S based on the AD values ​​obtained from the optical sensor 110, and performs a pass / fail determination of the sheet S based on these calculation results. Specifically, in step S309, the control unit 300 acquires AD values ​​from the RGB sensor 112 at a predetermined period (for example, 1 msec). Specifically, it acquires multiple AD values ​​from each color sensor. Note that when the sheet S reaches the measurable area of ​​the optical sensor 110, the thickness dimension of the leading edge of the sheet S tends to vary. Therefore, the acquisition of AD values ​​by the RGB sensor 112 is started after a predetermined time has elapsed. This allows for accurate acquisition of AD values.

[0086] Next, in step S310, the control unit 300 calculates the average value, standard deviation, maximum value, and minimum value for each color sensor using a predetermined number of AD values ​​acquired sequentially as the sheet S is transported.

[0087] Next, in step S311, the control unit 300 calculates the average value using only the AD values ​​that fall within a predetermined deviation range for each color sensor. This reduces the variability of the calculation results by excluding AD values ​​measured for unusual parts, such as black or white clumps formed on the sheet S.

[0088] Next, in step S312, the control unit 300 calculates the density (whiteness) of each color sensor based on a proportional formula (Figure 4D) using the average value calculated in step S311. Specifically, it calculates the density corresponding to the AD value of the R color sensor, the density corresponding to the AD value of the G color sensor, and the density corresponding to the AD value of the B color sensor.

[0089] Next, in step S313, the control unit 300 averages the densities of each color sensor calculated from the proportional formula in step S312. Specifically, it divides the sum of the densities of the R color sensor, the G color sensor, and the B color sensor by 3. This calculates the RGB densities (whiteness) of the sheet S.

[0090] Next, in step S314, the control unit 300 calculates the difference (difference in density) between the maximum and minimum values ​​of the density calculation values ​​between the color sensors calculated from the proportional formula in step S312. For example, it calculates the difference between the density (maximum value) calculated from the AD value of the R color sensor and the density (minimum value) calculated from the AD value of the B color sensor. From this, the RGB color difference on sheet S is calculated.

[0091] Next, in step S315, the control unit 300 determines whether the average concentration calculated in step S313 is equal to or greater than a predetermined value. The predetermined value in this step is the concentration determination threshold DS1 (Figure 5C) of the sheet S desired by the user. If it is determined that the average concentration is equal to or greater than the predetermined value (YES), the process proceeds to step S316. On the other hand, if it is determined that the average concentration is not equal to or greater than the predetermined value (NO), the process proceeds to step S318.

[0092] If the process proceeds to step S318, any sheet S whose average concentration is determined to be below a predetermined value is identified as unacceptable (defective), and the unacceptable sheet Sb is discharged to the second discharge section 96b.

[0093] If the process proceeds to step S316, the control unit 300 determines whether the density difference calculated in step S314 is less than or equal to a predetermined value. The predetermined value in this step is the RGB color difference determination threshold IS1 (Figure 5C) of sheet S. If it is determined that the density difference is less than or equal to the predetermined value (YES), the process proceeds to step S317. On the other hand, if it is determined that the density difference is not less than or equal to the predetermined value (NO), the process proceeds to step S318. If the process proceeds to step S318, sheet S, which was determined to have a density difference that is not less than or equal to the predetermined value, is judged to be unacceptable (defective), and the unacceptable sheet Sb is discharged to the second discharge unit 96b.

[0094] If the process proceeds to step S317, the sheet S, which is determined to have a density difference of less than or equal to a predetermined value, is judged to be a good product, and the good sheet Sa is discharged to the first discharge unit 96a. That is, as shown in Figure 5C, the good sheet Sa has a density (whiteness) of DS1 or greater and a color difference within the judgment threshold IS1. On the other hand, the bad sheet Sb has a density (whiteness) of less than the density judgment threshold DS1 and a color difference greater than the judgment threshold IS1.

[0095] According to this embodiment, it is possible to easily distinguish between sheets S (sheet Sa, sheet Sb) based on the density information (whiteness and color difference) of the formed sheet S. Furthermore, when the recycled sheet S is repeatedly recycled, the concentration of the sheet S decreases, the length of the fibers constituting the sheet S shortens, the adhesive strength between the fibers decreases, and the strength of the sheet S decreases. According to this embodiment, by identifying the sheet S based on the concentration information of the sheet S, it becomes possible to identify a sheet S that satisfies the required strength. By individually setting the density (whiteness) and color difference thresholds that define the identification of sheet S, users can easily identify sheet S of the quality they desire. [Explanation of symbols]

[0096] 1...Sheet manufacturing apparatus, 10...Supply unit, 12...Crushing unit, 20...Fibre removal unit, 40...Sorting unit, 50...Mixing unit, 60...Stacking unit, 70...Second web forming unit, 79...Conveying unit, 80...Sheet forming unit, 82...Pressing unit, 84...Heating unit, 90...Cutting unit, 96...Discharge unit, 96a...First discharge unit, 96b...Second discharge unit, 100...Detection unit, 110...Optical sensor, 111...Light emitting unit, 112...RGB sensor, 120...Reference member, 121...Reference color unit, 125...Rotation axis, 126...Protrusion, 127...Photo interrupter, 300...Control unit, CD1...First state, CD2...Second state, D1, D2...Distance, S, Sa, Sb...Sheet, W1...First web, W2...Second web.

Claims

1. A defibration unit that defibrates waste paper to produce defibrated material, A deposit section where the aforementioned defibrated material is deposited to form a web, A sheet forming unit that forms a sheet by heating and compressing the web, A cutting section for cutting the aforementioned sheet to a predetermined length, A waste paper recycling apparatus comprising: an optical sensor provided on the exit side of the sheet forming section, which measures the conveyed sheets at predetermined intervals and measures multiple concentration information of the sheets.

2. A waste paper recycling apparatus according to claim 1, The aforementioned density information includes the density of each RGB color component of the sheet's color and the RGB color difference of the sheet, in a recycled paper apparatus.

3. A waste paper recycling apparatus according to claim 1 or claim 2, The optical sensor is located between the sheet forming section and the cutting section of the recycled paper apparatus.

4. A waste paper recycling apparatus according to any one of claims 1 to 3, A waste paper recycling apparatus comprising a reference member provided at a position opposite the optical sensor, which performs calibration of the optical sensor based on the measurement result of a reference color portion provided on the reference member.

5. A waste paper recycling apparatus according to claim 4, A waste paper recycling apparatus in which the reference member is held so as to be rotatable, the reference color portion faces the optical sensor when the calibration is performed, and the reference member rotates so that the reference color portion faces away from the optical sensor while the waste paper recycling apparatus is in operation.

6. A waste paper recycling apparatus according to claim 5, A waste paper recycling apparatus in which, when the reference color portion faces the optical sensor, the distance between the surface of the reference color portion and the optical sensor is equal to the distance between the sheet and the optical sensor when the waste paper recycling apparatus is in operation.

Images