Paper type identification device and image forming apparatus

Abstract

To provide a paper type identification device that can accurately identify the type of paper even when using a measuring instrument that can measure only a single side of a sheet.SOLUTION: A paper type identification device 100 comprises: a surface property measurement unit 103 that measures the feature quantity of a single side of a sheet to be identified; and a control unit 400 that identifies the type of the sheet based on a result of measurement performed by the surface property measurement unit 103. Upon completion of the measurement of the feature quantity of one face of the sheet performed by the surface property measurement unit 103, the control unit 400 causes an operation unit 502 to issue a notification to prompt measurement of the other face of the sheet.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a paper type identification device capable of identifying the type of a sheet, and an image forming apparatus including such a paper type identification device.

Background Art

[0002] Electrophotographic image forming apparatuses such as copiers, printers, facsimiles, and multifunction peripherals form an image on a sheet conveyed through a conveyance path by each of the processes of charging, exposure, development, transfer, and fixing. There are various types of sheets that can be used for image formation. Sheets have different characteristics (physical properties) such as paper thickness, smoothness, basis weight, and surface properties depending on the type. The optimum operating conditions in each process of image formation vary depending on the physical properties (stiffness, basis weight, surface properties, etc.) of the sheet used. Therefore, an image forming apparatus needs to change operating conditions such as adjustment values for each process based on the type of the sheet. When a user uses an image forming apparatus, the user registers in advance the type of the sheet to be used. However, if an incorrect type is set, the image forming apparatus cannot form an image under appropriate operating conditions. In this case, a normal image cannot be formed on the sheet. For example, an abnormality occurs in the image formed on the sheet due to the occurrence of a jam, poor fixing, poor image density, or the like.

[0003] Patent Document 1 discloses an image forming apparatus that identifies the type of a sheet by a measuring instrument (media sensor) that measures a feature amount of the sheet and performs image formation. The measuring instrument notifies the image forming apparatus of the measurement result of the sheet. The image forming apparatus detects a paper profile that matches the measurement result from a plurality of pre-registered paper profiles and displays it on a display unit. Thereby, incorrect setting of the type of the sheet is reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] Measuring instruments that measure the feature quantities of sheets manually inserted by the user may only be able to measure one side of the sheet due to cost and configuration constraints. In this case, only the feature quantities of one side of the sheet are measured. Image forming machines register the feature quantities of the front (printed side) in the paper profile and identify the paper type by reading only the front side of the sheet during measurement with the measuring instrument. However, if the feature quantities differ between the front and back sides, and the sheets look the same on both sides (for example, recycled paper), the risk of mistakenly measuring the front and back sides increases. The difference in feature quantities between the front and back sides can cause misidentification of the paper type.

[0006] In view of the above-mentioned problems, the primary objective of the present invention is to provide a paper type identification device that can accurately identify the type of paper even when using a measuring instrument that can only measure one side of a sheet. [Means for solving the problem]

[0007] The paper type identification device of the present invention comprises: a reading sensor for reading the surface of a sheet; a control means for controlling the reading sensor to read a first surface of the sheet and obtain a first reading result; controlling the reading sensor to read a second surface of the sheet different from the first surface and obtain a second reading result; and identifying the type of the sheet based on the first reading result and the second reading result. The control means performs a first mode in which the type of sheet is determined based on the first reading result and the second reading result, and a second mode in which the type of sheet is determined based on the first reading result, and the control means receives user instruction information instructing the execution of the first mode, and selects the first mode based on the received user instruction information. It is characterized by the following. Another paper type identification device of the present invention comprises: a reading sensor for reading the surface of a sheet; a control means for controlling the reading sensor to read a first surface of the sheet and obtain a first reading result, controlling the reading sensor to read a second surface of the sheet different from the first surface and obtain a second reading result, and identifying the type of the sheet based on the first reading result and the second reading result; and a display, wherein the control means performs a first mode for determining the type of the sheet based on the first reading result and the second reading result, and a second mode for determining the type of the sheet based on the first reading result, and the display displays a screen on which the user can select whether or not to perform the first mode after the reading sensor has read the first surface of the sheet. The present invention relates to an image forming apparatus for forming an image on a sheet based on image forming conditions, comprising: a reading sensor for reading the surface of the sheet; a control means for controlling the reading sensor to read a first surface of the sheet and obtain a first reading result; a control means for controlling the reading sensor to read a second surface of the sheet different from the first surface and obtain a second reading result; and a display, wherein the control means executes a first mode in which a plurality of candidates for the type of sheet is displayed on the display based on the first reading result and the second reading result; and a second mode in which the plurality of candidates for the type of sheet is displayed on the display based on the first reading result; and the control means selects the first mode based on the user instruction information when it receives user instruction information instructing the execution of the first mode. Another image forming apparatus of the present invention is an image forming apparatus for forming an image on a sheet based on image forming conditions, comprising: a reading sensor for reading the surface of the sheet; a control means for controlling the reading sensor to read a first surface of the sheet and obtain a first reading result; a control means for controlling the reading sensor to read a second surface of the sheet different from the first surface and obtain a second reading result; and a display, wherein the control means executes a first mode in which a plurality of candidates for the type of sheet is displayed on the display based on the first reading result and the second reading result; and a second mode in which the plurality of candidates for the type of sheet is displayed on the display based on the first reading result, wherein after the reading sensor has read the first surface of the sheet, the control means displays a selection screen on the display in which the user can select whether or not to execute the first mode. [Effects of the Invention]

[0008] According to the present invention, even when using a measuring instrument that can only measure one side of a sheet, it is possible to accurately identify the type of paper. [Brief explanation of the drawing]

[0009] [Figure 1] Configuration diagram of an image forming apparatus. [Figure 2] (a) and (b) are enlarged views of the fixing device 201. [Figure 3] Explanatory diagram of the control unit. [Figure 4] (a) and (b) are explanatory diagrams of the paper type identification device. [Figure 5] (a) and (b) are explanatory diagrams of the paper type identification device. [Figure 6] Explanatory diagram of the paper type identification device. [Figure 7] Explanatory diagram of the line sensor. [Figure 8] Explanatory diagram of the paper type database. [Figure 9] Flowchart representing the parameter acquisition process. [Figure 10] Exemplary diagram of the operation screen. [Figure 11] Exemplary diagram of the operation screen. [Figure 12] Exemplary diagram of the operation screen. [Figure 13] Exemplary diagram of the operation screen. [Figure 14] Explanatory diagram of the relationship between the ultrasonic transmittance and the basis weight. [Figure 15] Flowchart representing the paper type identification process. [[ID=*5]] [Figure 16] Explanatory diagram of the classification of surface properties. [Figure 17] Exemplary diagram of the brand candidate screen. [Figure 18] Exemplary diagram of the brand candidate screen.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, exemplary preferred embodiments of this invention will be described in detail with reference to the drawings.

[0011] <* (Image Forming Apparatus) Figure 1 is a configuration diagram of the image forming apparatus of this embodiment. The image forming apparatus 201 of this embodiment is a tandem-intermediate transfer type laser beam printer that utilizes an electrophotographic process. The image forming apparatus 201 forms and outputs full-color or monochrome images on a recording medium sheet P based on image data acquired from an external device such as a personal computer via a network, or image data acquired from an image reading device 300.

[0012] The image forming apparatus 201 has components for forming images inside the main body 201A, and an image reading device 300, an operation unit 502, and a paper type identification device 100 are provided on the upper part of the main body 201A. Between the main body 201A and the image reading device 300 of the image forming apparatus 201, there is an discharge space S through which the sheet P after image formation is discharged.

[0013] The image reading device 300 is a scanner that reads an image from a document and generates image data. The image reading device 300 is used during the document copying process. The operation unit 502 is a user interface equipped with an input interface and an output interface. The input interface is, for example, various key buttons, a touch panel, etc. The output interface is a display, a speaker, etc. The user can input various instructions to the image forming apparatus 201 using the operation unit 502. The paper type identification device 100 is a device for identifying the type of sheet P used for image formation (printing) by the image forming apparatus 201. Details of the paper type identification device 100 will be described later.

[0014] The image forming apparatus 201 includes an image forming unit 201B, an intermediate transfer unit 201C, a secondary transfer unit 201D, a fuser 201E, and a cassette paper feed unit 230 within the main body 201A.

[0015] The cassette paper feed unit 230 feeds sheets P from the paper feed cassette 1 which stores the sheets P. The cassette paper feed unit 230 includes a pickup roller 2 and a separation unit consisting of a feed roller 3 and a retard roller 4 for separating the sheets P fed out from the pickup roller 2. The sheets P are fed one by one from the paper feed cassette 1 by the pickup roller 2 and the separation unit. In this embodiment, a configuration in which multiple (four in this case) cassette paper feed units 230 are provided is described, but there may be any number of cassette paper feed units 230. The sheets P fed from the cassette paper feed unit 230 are transported along the transport path to the register roller pair 240.

[0016] In addition to the cassette paper feed unit 230, the sheets P can also be fed from the manual feed unit 235. The manual feed unit 235 is equipped with a manual feed tray 5 on which the user places the sheets P. Similar to the cassette paper feed unit 230, the manual feed unit 235 is equipped with a pickup roller and a separation unit, and feeds the sheets P one by one from the manual feed tray 5. The sheets P fed from the manual feed unit 235 are also transported along the transport path to the register roller pair 240.

[0017] The image forming unit 201B is a 4-drum full-color system and includes a laser scanner 210 and four process cartridges 211 that form toner images of four colors: yellow (Y), magenta (M), cyan (C), and black (K). Each process cartridge 211 includes a photosensitive drum 212, a charger 213, and a developer 214. A toner cartridge 215 is positioned above the process cartridges 211. The toner cartridge 215 supplies toner to the developer 214.

[0018] The intermediate transfer section 201C includes an intermediate transfer belt 216 wrapped around a drive roller 216a and a tension roller 216b. Inside the intermediate transfer belt 216 are four primary transfer rollers 219 that contact the intermediate transfer belt 216 at positions opposite each photosensitive drum 212. The intermediate transfer belt 216 rotates in the direction of the arrow by the drive roller 216a, which is driven by a drive unit (not shown).

[0019] The secondary transfer unit 201D includes a secondary transfer roller 217 positioned opposite the drive roller 216a, sandwiching the intermediate transfer belt 216. The fuser 201E is located downstream of the secondary transfer roller 217 in the sheet P transport direction and includes a pressure roller 220a and a heating roller 220b. Downstream of the fuser 201E in the sheet P transport direction, a first discharge roller pair 225a, a second discharge roller pair 225b, and a double-sided reversal unit 201F are arranged. The double-sided reversal unit 201F includes a reversible reversible roller pair 222 and a re-transport passage R for transporting the sheet P, on which an image has been formed on one side, to the image forming unit 201B.

[0020] The image forming apparatus 201, configured as described above, operates as follows: The image forming apparatus 201 acquires image data from the image reading device 300 or an external device and forms an image on the sheet P corresponding to the image data. In this process, the image forming apparatus 201 performs each image forming step under operating conditions corresponding to the type of sheet P.

[0021] The image forming unit 201B uniformly charges the surface of the photosensitive drum 212 to a predetermined polarity using the charger 213. The laser scanner 210 irradiates the uniformly charged surface of the photosensitive drum 212 with laser light modulated based on the image data. As a result, an electrostatic latent image corresponding to the color (yellow, magenta, cyan, black) is formed on the surface of each photosensitive drum 212.

[0022] The image forming unit 201B develops the electrostatic latent image formed on the photosensitive drum 212 by the developer unit 214. On each photosensitive drum 212, the electrostatic latent image is developed with toner of the corresponding color, forming a toner image of the corresponding color. The toner images are sequentially transferred from the photosensitive drum 212 to the rotating intermediate transfer belt 216 by the primary transfer roller 219. This forms a full-color toner image on the intermediate transfer belt 216. The intermediate transfer belt 216 rotates to transport the toner image to the secondary transfer unit 201D.

[0023] In parallel with this toner image formation operation, the sheets P are transported one by one to the register roller pair 240 by the cassette paper feed unit 230 or the manual paper feed unit 235. The register roller pair 240 corrects the skewness of the transported sheets P. After the skewness is corrected, the sheets P are transported by the register roller pair 240 to the secondary transfer unit 201D at the same time that the toner image carried by the intermediate transfer belt 216 is transported to the secondary transfer unit 201D. The secondary transfer unit 201D transfers the full-color toner image from the intermediate transfer belt 216 onto the sheets P using a secondary transfer bias applied to the secondary transfer roller 217.

[0024] The sheet P onto which the toner image has been transferred is transported to the fuser unit 201E. The fuser unit 201E grips and transports the sheet P using a roller nip section formed by a pressure roller 220a and a heating roller 220b. When gripping and transporting the sheet P, the fuser unit 201E heats the sheet P with the heating roller 220b, melting and mixing the toners of each color on the sheet P. The fuser unit 201E also pressurizes the sheet P with the pressure roller 220a, fixing the melted and mixed toners to the sheet P. At this time, the adhesive force of the melted toner generates a force that causes the sheet P to stick to the heating roller 220b.

[0025] Figure 2 is an enlarged view of the fuser unit 201E. If the rigidity (stiffness) of the sheet P is weak, the adhesive force generated on the sheet P against the heating roller 220b may cause the sheet P to be wound up by the rotating heating roller 220b (Figure 2(b)). For this reason, a separation plate 202 for separating the sheet P is provided downstream of the heating roller 220b in the direction of sheet P transport (Figure 2(a)).

[0026] The image forming apparatus 201 may determine the state of the separation plate 202 according to the type of sheet P. For example, when forming an image on a sheet P of low rigidity, the separation plate 202 is positioned so that its tip contacts the surface of the heating roller 220b, as shown in Figure 2(a), to separate the sheet P from the heating roller 220b. When forming an image on a sheet P of high rigidity, the sheet P is not wound onto the heating roller 220b. For this reason, the separation plate 202 is positioned so that its tip does not contact the surface of the heating roller 220b. This prevents the surface of the heating roller 220b from being worn down by the separation plate 202.

[0027] The sheet P on which the image has been fixed is discharged into the discharge space S by either the first discharge roller pair 225a or the second discharge roller pair 225b. The sheet P is then loaded onto the loading section 223, which is provided protruding from the bottom surface of the discharge space S. When an image is to be formed on both sides of the sheet P, the sheet P on which the image has been fixed on one side is transported to the re-transport passage R by the reversing roller pair 222, and then transported again to the image forming section 201B, where an image is formed on the reversed side.

[0028] (Control Unit) Figure 3 is an explanatory diagram of the control unit that controls the operation of such an image forming apparatus 201. The control unit 400 is an information processing device equipped with, for example, a CPU (Central Processing Unit). The control unit 400 may also be implemented using an MPU (Micro Processor Unit) or an ASIC (Application Specific Integrated Circuit). The control unit 400 controls the image forming process performed by the image forming apparatus 201. In this embodiment, the control unit 400 is connected to the paper type identification device 100 and controls the paper type identification device 100. The control unit 400 is connected to a memory 401 and an operation unit 502. The memory 401 includes a paper type database 402. The paper type database 402 stores information such as the characteristic quantities of various types of sheets, parameters of the operating conditions of each component during optimal image forming, whether paper can be fed into the image forming apparatus 201, and usable paper feed slots.

[0029] The paper type identification device 100 includes an information processing unit 160. The information processing unit 160 is an information processing device implemented by, for example, a CPU, MPU, or ASIC. The information processing unit 160 is communicatively connected to the control unit 400 and operates in cooperation with the control unit 400. The information processing unit 160 is connected to an upstream sheet sensor 104, a downstream sheet sensor 105, a mechanical property measurement unit 102, and a surface property measurement unit 103. The mechanical property measurement unit 102 includes an ultrasonic sensor 120 and a paper thickness sensor 140. The surface property measurement unit 103 includes an optical sensor 150. The information processing unit 160 controls the operation of the upstream sheet sensor 104, the downstream sheet sensor 105, the mechanical property measurement unit 102, and the surface property measurement unit 103, and acquires the measurement results of each.

[0030] The upstream sheet sensor 104 is a sensor that detects the insertion of sheet P into the paper type identification device 100. When the upstream sheet sensor 104 detects sheet P, the information processing unit 160 starts the measurement sequence for the feature quantities of sheet P. The downstream sheet sensor 105 is a sensor that detects when sheet P has reached the innermost part of the paper type identification device 100 into which sheet P can be inserted (the stopper part described later). The ultrasonic sensor 120 is a sensor used to measure the basis weight of sheet P. The paper thickness sensor 140 is a sensor used to measure the paper thickness of sheet P. The optical sensor 150 is a sensor used to measure the adjacent pixel difference integrated value and surface information such as brightness of sheet P. The adjacent pixel difference integrated value is the value obtained by accumulating the difference between the detected values ​​(measurement results) for each adjacent pixel in the measurement direction of one line by the optical sensor 150. The optical sensor 150 outputs the brightness value for each pixel as the measurement result. The information processing unit 160 stores the measurement results and generates surface property information based on the measurement results. Details of the ultrasonic sensor 120, paper thickness sensor 140, and optical sensor 150 will be described later.

[0031] The information processing unit 160 transmits the mechanical property information (basis weight and paper thickness) acquired by the mechanical property measurement unit 102 and the surface property information acquired by the surface property measurement unit 103 to the control unit 400. The control unit 400 determines the paper type of sheet P based on the acquired surface property information. Subsequently, the control unit 400 identifies the brand name of sheet P based on the paper type and mechanical property information (basis weight and paper thickness) using the paper type database 402 and displays it on the display of the operation unit 502.

[0032] (Types of sheets used in image forming apparatus) The operating conditions of each component in each step of the image formation process (such as transport speed during fixing, fixing temperature, and transfer voltage during secondary transfer) vary depending on the characteristic quantities (physical properties) of the sheet P on which the image is formed, such as basis weight, stiffness, surface properties, and material properties. Therefore, it is important to know in advance what type of sheet P will be used during image formation.

[0033] There may be restrictions on how sheets P can be loaded into the paper feed slot of the image forming apparatus 201. The paper feed slots are the paper feed cassette 1 and the manual feed tray 5. For example, some thick paper with high rigidity can only be fed from the manual feed tray 5, which has a small curvature in its transport path. Coated paper, which has a smooth surface and strong adhesion between sheets, must be fed one sheet at a time from the manual feed tray 5. Paper made from pulp generally has different bending rigidity depending on the direction of the paper, due to the bias in the orientation direction (grain direction) of the pulp fibers that occurs due to the manufacturing process. For this reason, some pulp-based papers have recommended orientations for loading into the paper feed slot to minimize bending rigidity in the transport path. Also, single-sided coated paper, which is coated on only one side compared to plain paper, has a specified up and down orientation when loading in order to form an image on the coated surface.

[0034] Some sheets cannot be used with the image forming apparatus 201. For example, thick paper with excessive stiffness may cause the paper to stop being transported due to the resistance when it is transported along the curved transport path. Thin paper with excessive stiffness is strongly affected by the adhesive force between the molten toner and the heating roller 220b as it passes through the fuser unit 201E, as described above. As a result, paper with excessive stiffness may not be peeled off the heating roller 220b by the separation plate 202 and may become wrapped around it (Figure 2(b)). In addition, synthetic paper made from synthetic resin instead of pulp may melt when heated in the fuser unit 201E, potentially contaminating the heating roller 220b.

[0035] (Paper type identification device) Figures 4, 5, and 6 are explanatory diagrams of the paper type identification device 100. Figure 4 shows the state before sheet P is inserted into the paper type identification device 100. Figure 5 shows the state after sheet P has been inserted into the paper type identification device 100. Figures 4(a) and 5(a) are views of the paper type identification device 100 from the side (the front direction of the image forming apparatus 201 in Figure 1). Figures 4(b) and 5(b) are views of the paper type identification device 100 from above. Figure 6 is a view of the paper type identification device 100 from the direction in which sheet P is inserted.

[0036] The paper type identification device 100 has a groove 101 into which the sheet P to be identified is inserted, and measures the characteristic quantities of the sheet P inserted from the groove 101. The insertion of the sheet P is performed manually by the user. The groove 101 has an upper block 109 at the top and a lower block 110 at the bottom.

[0037] A sheet retaining member 106 is provided at the back of the groove in the lower block 110. The sheet retaining member 106 is biased toward the upper block 109 by a biasing member 107. The sheet P is inserted by pushing the sheet retaining member 106 downwards. The upper block 109 protrudes toward the lower block 110 at the end of the sheet retaining member 106 (the innermost part into which the sheet P can be inserted), forming a stopper portion 108. Because the stopper portion 108 restricts the insertion of the sheet P, the sheet P can only be inserted up to the stopper portion 108. An information processing unit 160 is located behind the stopper portion 108.

[0038] The measurement unit for measuring the characteristics of sheet P consists of a mechanical property measurement unit 102 and a surface property measurement unit 103, as described above. As sheet P passes through the measurement unit, characteristic values ​​such as basis weight, surface property, and paper thickness of sheet P are acquired. An upstream sheet sensor 104 is positioned upstream of the surface property measurement unit 103 in the insertion direction of sheet P. A downstream sheet sensor 105 is positioned near the upstream side of the abutment unit 108 in the insertion direction of sheet P. In other words, the upstream sheet sensor 104 is positioned at the insertion start position of sheet P, and the downstream sheet sensor 105 is positioned at the insertion end position of sheet P. The upstream sheet sensor 104 and the downstream sheet sensor 105 each detect the inserted sheet P.

[0039] As shown in Figure 6, the mechanical property measurement unit 102 is configured such that the ultrasonic transmitter 130 is on the lower block 110 side and the ultrasonic receiver 131 is on the upper block 109 side, flanking the insertion passage through which the sheet P is inserted. The ultrasonic transmitter 130 and ultrasonic receiver 131 constitute an ultrasonic sensor 120. The mechanical property measurement unit 102 can detect the basis weight of the sheet P by transmitting and receiving ultrasonic waves through the insertion passage of the sheet P using the ultrasonic sensor 120. Basis weight is the mass per unit area of ​​the sheet P and is expressed in units of [gsm].

[0040] Both the ultrasonic transmitter 130 and the ultrasonic receiver 131 consist of a piezoelectric element (also called a piezo element), which is an element that converts mechanical displacement and electrical signals, and electrode terminals. When a pulse voltage of a predetermined frequency is input to the electrode terminals of the ultrasonic transmitter 130, the piezoelectric element oscillates and generates ultrasonic waves. The generated ultrasonic waves propagate through the air. When the ultrasonic waves reach the sheet P, the sheet P vibrates due to the ultrasonic waves. The ultrasonic waves generated by the ultrasonic transmitter 130 propagate through the sheet P to the ultrasonic receiver 131. The piezoelectric element of the ultrasonic receiver 131 generates an output voltage at its electrode terminals corresponding to the amplitude of the received ultrasonic waves. The output voltage is a voltage value corresponding to the basis weight of the sheet P. The output voltage is transmitted to the information processing unit 160 as a measured value.

[0041] Compared to the case where there is no sheet P between the ultrasonic transmitter 130 and the ultrasonic receiver 131, the output voltage due to the ultrasound transmitted through sheet P is attenuated. The information processing unit 160 calculates the transmittance of sheet P based on the ratio of the output voltage with and without sheet P. Since the transmittance of ultrasound changes depending on the thickness of sheet P, the information processing unit 160 can estimate the basis weight of sheet P using the ultrasonic transmission coefficient-basis weight conversion formula. In this way, the basis weight of sheet P is detected using the ultrasonic sensor 120.

[0042] The upstream sheet sensor 104, located on the upper block 109 upstream of the surface quality measurement unit 103 in the insertion direction of the sheet P, detects the insertion of the sheet P into the paper type identification device 100. The downstream sheet sensor 105, located on the upper block 109 downstream of the surface quality measurement unit 103 in the insertion direction of the sheet P, detects the arrival of the fully inserted sheet P at the abutment portion 108.

[0043] The paper thickness sensor 140 is positioned near the abutment portion 108. The paper thickness sensor 140 is lever-type, and as the lever tilts according to the thickness of the sheet P, the encoder rotates according to the amount the lever is tilted. While the encoder is rotating, the paper thickness sensor 140 transmits a pulse signal as a measured value of the paper thickness to the information processing unit 160. The paper thickness sensor 140 is positioned slightly downstream of the downstream sheet sensor 105 in the insertion direction of the sheet P, so that the paper thickness can be measured when the downstream sheet sensor 105 detects the sheet P.

[0044] As described above, the surface quality measurement unit 103 includes an optical sensor 150 for detecting the surface quality of the sheet P. The optical sensor 150 comprises a light-emitting unit 132 and a line sensor 133. The optical sensor 150 is, for example, a CIS (Contact Image Sensor). The light-emitting unit 132 is, for example, an LED (Light Emitted Diode). The line sensor 133 is composed of multiple light-receiving elements arranged in a row. For example, the line sensor 133 may be a CMOS line sensor equipped with a CMOS sensor as a light-receiving element.

[0045] As shown in Figure 6, the surface measurement unit 103 (optical sensor 150) is equipped with a light-emitting unit 132 and a line sensor 133 on the upper block 109 side. The line sensor 133 has multiple light-receiving elements arranged in a direction intersecting the insertion direction of the sheet P of the paper type identification device 100. Therefore, the line sensor 133 detects the surface of the sheet P by considering the direction intersecting the insertion direction of the sheet P as one line. The line sensor 133 is capable of detecting the paper surface area with a resolution corresponding to the pixel size and the imaging magnification of the optical system.

[0046] The amount of light reflected from sheet P to line sensor 133 varies depending on the surface properties of sheet P. For example, glossy paper has a smoother surface (less unevenness) than plain paper. Therefore, glossy paper has a larger amount of specularly reflected light and a smaller amount of diffusely reflected light compared to plain paper. In other words, the amount of reflected light substantially indicates the smoothness of the surface of sheet P. By using the amount of specularly reflected light, diffusely reflected light, or both, from sheet P incident on line sensor 133, the type of sheet P can be determined. Line sensor 133 is configured to sample reflected light based on a clock signal with a predetermined sampling frequency. In this embodiment, the surface properties of sheet P are measured using the surface properties measurement unit 103, and the results of multiple samplings are used.

[0047] The surface quality measuring unit 103 needs to hold the sheet P at the optical focal position. To this end, the biasing member 107 biases the sheet P toward the surface quality measuring unit 103 using the sheet holding member 106 to stabilize its orientation. This reduces variations in the position and orientation of the sheet P when detecting its surface, allowing the surface quality measuring unit 103 to reliably detect surface quality. The biasing member 107 is set to press the inserted sheet P toward the surface quality measuring unit 103 with a force of approximately 100 gf.

[0048] Figure 7 is an explanatory diagram of the line sensor 133. The line sensor 133 can detect n pixels of an image at once in a direction perpendicular to the insertion direction of the sheet P. To achieve this, the photodetectors are arranged in series, for example, n of them in a direction perpendicular to the insertion direction of the sheet P.

[0049] (superficial information) The information processing unit 160 performs digital processing on the image detected by the optical sensor 150 and obtains the detected value (luminance value) for each pixel. The detected value (luminance value) is stored in the memory inside the information processing unit 160. Based on the detected value stored in the memory, the information processing unit 160 obtains the adjacent pixel difference integrated value and brightness as surface information. The information processing unit 160 stores the surface information in the memory.

[0050] As described above, the adjacent pixel difference integrated value is the value obtained by accumulating the differences in detected values ​​(luminance values) of adjacent pixels in the direction of one line, and serves as an indicator of the surface irregularities of sheet P. If the detected values ​​of each pixel (result of one sampling) in Figure 7 are denoted as "A1" to "An" according to the pixel position, the adjacent pixel difference integrated value k is expressed by the following formula. k = | A2-A1 | + | A3-A2 | …+ | An-A(n-1) |

[0051] Brightness is the integrated value of the detection values ​​of each pixel of the optical sensor 150, and is a parameter that correlates with the reflectance (brightness) of the sheet P. For example, transparent films made of resin such as PET are measured as having low brightness because they reflect little light. Sheet P with a geometric uneven surface, such as embossed paper, has a large difference in brightness between adjacent pixels due to the unevenness, resulting in a large integrated difference between adjacent pixels. Recycled paper tends to be measured as having a rough surface because the grain direction is uneven and the pulp fibers become shorter after going through several recycling processes. Coated paper appears to have less unevenness due to the coating layer on the surface, so the integrated difference between adjacent pixels tends to be small.

[0052] (Paper type database) Figure 8 is an explanatory diagram of the paper type database 402 stored in the memory 401 of the image forming apparatus 201. The paper type database 402 stores feature quantities measured by the paper type identification device 100, linked to brand information. The feature quantities are physical properties (basis weight, paper thickness), surface quality information (first surface quality) representing the surface quality of the surface (printed surface), and surface quality information (second surface quality) representing the surface quality of the back surface. The surface quality information includes adjacent pixel difference integrated values ​​and brightness.

[0053] (Paper type identification) Figure 9 is a flowchart showing the parameter acquisition process for identifying the paper type of sheet P. Figures 10, 11, 12, and 13 are illustrative diagrams of the operation screen displayed on the display of the operation unit 502 during the parameter acquisition process. When using sheet P, the user displays the operation screen exemplified in Figure 10 on the display of the operation unit 502. This operation screen includes a "Manual Sheet Selection" button for the user to manually input the type of sheet P, and a "Automatic Sheet Identification" button for the paper type identification device 100 to automatically select the type of sheet P. In this embodiment, the user selects the "Automatic Sheet Identification" button from the selection screen using the operation unit 502, and the selection is input to the control unit 400.

[0054] When the control unit 400 receives information from the operation unit 502 indicating that the "Automatic Sheet Identification" button has been selected, it sets the operation mode to the automatic sheet identification mode for sheet P (S1). Once the automatic identification mode is set, the control unit 400 instructs the information processing unit 160 of the paper type identification device 100 to measure sheet P. In response to this instruction, the information processing unit 160 performs initialization processing for the mechanical property measurement unit 102 and the surface property measurement unit 103. Also, once the automatic identification mode is set, the control unit 400 displays the operation screen illustrated in Figure 11 on the display of the operation unit 502. This operation screen includes a "Single-Sided Reading" button for measuring only one side of sheet P and a "Double-Sided Reading" button for measuring both sides of sheet P. The user selects either button to measure one side or both sides of sheet P. The control unit 400 receives information from the operation unit 502 indicating that either the "Single-Sided Reading" button or the "Double-Sided Reading" button has been selected (S2). When the surface to be measured is selected, the control unit 400 displays an operation screen as illustrated in Figure 12 on the display of the operation unit 502 and instructs the user to insert the sheet P (S3). The user then begins inserting the sheet P into the groove 101 of the paper type identification device 100 in accordance with this operation screen.

[0055] When the initialization process is completed in the process of S1, the information processing unit 160 waits for the insertion of the sheet P into the groove 101. When the user inserts the sheet P into the groove 101 according to the operation screen in Figure 12, the information processing unit 160 starts measuring the feature quantities of the surface (first surface) of the sheet P (S4). The measurement of the feature quantities is performed as follows. When the measurement of the feature quantities of the surface (first surface) is completed, the information processing unit 160 notifies the control unit 400 that the measurement has been completed.

[0056] The information processing unit 160, triggered by the detection of sheet P by the upstream sheet sensor 104, starts measuring the surface properties of sheet P by the surface property measurement unit 103 (optical sensor 150) after a predetermined time has elapsed. The information processing unit 160 causes the optical sensor 150 to read sheet P and sequentially acquires the reading results (detected values). The optical sensor 150 measures the surface properties of sheet P by scanning the transported sheet P multiple times at predetermined time intervals. The information processing unit 160 performs the above processing on the reading results (detected values) from the optical sensor 150 to generate surface property information and stores it in internal memory.

[0057] The information processing unit 160 starts measuring the physical properties of sheet P using the mechanical property measurement unit 102 after a predetermined time t2 (t2 > t1) has elapsed since the upstream sheet sensor 104 detected sheet P. The information processing unit 160 measures the ultrasonic transmittance of sheet P using the ultrasonic sensor 120, converts the measured value into basis weight information, and stores the basis weight information in memory. Figure 14 is an explanatory diagram of the relationship between ultrasonic transmittance and basis weight. The information processing unit 160 maintains a conversion formula or conversion table that shows the relationship between ultrasonic transmittance and basis weight. The information processing unit 160 converts the measured value into basis weight using such a conversion formula or conversion table. Through this measurement of physical properties, the basis weight information of sheet P is stored in the memory of the information processing unit 160. The information processing unit 160 also waits for the count of pulse signals output from the paper thickness sensor 140, triggered by the detection of sheet P by the upstream sheet sensor 104.

[0058] The information processing unit 160 waits until the downstream sheet sensor 105 detects sheet P. The downstream sheet sensor 105 detects sheet P when it has been inserted to the innermost abutment portion 108. When the downstream sheet sensor 105 detects sheet P, the information processing unit 160 acquires a pulse signal, which is a measured value, from the paper thickness sensor 140. The information processing unit 160 measures the paper thickness of sheet P based on the number of pulse signals (number of pulses) acquired. The paper thickness of sheet P is stored in the memory of the information processing unit 160. Also, when the downstream sheet sensor 105 detects sheet P, the information processing unit 160 stops reading sheet P by the optical sensor 150 of the surface quality measurement unit 103.

[0059] When the control unit 400 receives notification from the information processing unit 160 that the measurement of the surface feature quantities has been completed, it checks in process S2 whether single-sided measurement or double-sided measurement was selected (S5). If single-sided measurement is selected (S5:Y), the control unit 400 obtains the measurement results (feature quantities) of the surface (first surface) from the information processing unit 160, performs the paper type identification process described later, and displays the candidate paper brands for the sheet on the display of the operation unit 502 (S6). The user checks the candidate paper brands displayed on the display and decides whether or not to perform measurement on the back side (second surface). Depending on the decision, the user instructs the operation unit 502 whether or not to perform measurement on the back side. For example, the user decides to perform measurement on the back side if the expected paper brand is not included in the candidate paper brands.

[0060] The control unit 400 receives an instruction from the operation unit 502 to determine whether or not to perform measurement on the back side (S7). If measurement on the back side is not performed (S7:N), the control unit 400 terminates the parameter acquisition process. If measurement on the back side is performed (S7:Y), the control unit 400 displays the operation screen illustrated in Figure 13 on the display of the operation unit 502 and instructs the user to insert sheet P (S8). If double-sided measurement is selected (S5:N), the control unit 400 does not perform the processes in S6 and S7, but displays the operation screen illustrated in Figure 13 on the display of the operation unit 502 and instructs the user to insert sheet P (S8). The operation screen in Figure 13 notifies the user to reverse the front and back sides of sheet P and insert it into the paper type identification device 100.

[0061] The information processing unit 160 measures the feature quantities of the back side (second side) of the inserted sheet P, similar to the process in S4 (S9). When the information processing unit 160 finishes measuring the feature quantities of the back side (second side), it notifies the control unit 400 that the measurement is complete. When the control unit 400 receives notification from the information processing unit 160 that the measurement of the feature quantities of the back side is complete, it obtains the measurement results (feature quantities) of the front and back sides from the information processing unit 160, performs the paper type identification process described later, and displays the candidate sheet brands on the display of the operation unit 502 (S10). With this, the parameter acquisition process is completed.

[0062] Figure 15 is a flowchart illustrating the paper type identification process performed in processes S6 and S10. Here, we will explain the paper type identification process for both single-sided measurement (process S6) and double-sided measurement (process S10).

[0063] In the case of single-sided measurement, the control unit 400 identifies the paper type based on the measurement results (feature quantities) of the surface (first surface). The control unit 400 classifies the type of sheet P based on the measurement results of the surface properties of the sheet P (S21). Figure 16 is an explanatory diagram of the classification of surface properties. In Figure 16, a matrix is ​​used as an index of surface properties, with the vertical axis representing the integrated difference value of adjacent pixels and the horizontal axis representing brightness, and the surface properties of sheet P are measured and classified in advance. The control unit 400 refers to the matrix according to the surface property information (integrated difference value of adjacent pixels and brightness) obtained from the detected values ​​detected by the optical sensor 150 and classifies the type of sheet P. The control unit 400 classifies the type of sheet P by selecting a brand from the paper type database 402 whose measurement results (surface property information) match the sheet information of the first surface properties in the paper type database 402.

[0064] The control unit 400 selects a paper brand within a predetermined range of measured basis weight (e.g., ±5 [gsm]) based on classification by surface properties (S22). Furthermore, the control unit 400 selects a paper brand within a predetermined range of measured paper thickness (e.g., ±5 [μm]) from the selected brands (S23). The control unit 400 displays the selected sheet brand candidates on the display of the operation unit 502 (S24). By using basis weight and paper thickness as parameters for paper type selection in addition to surface property information, the brands are further selected and the accuracy of brand identification is improved.

[0065] Figure 17 is an example of the candidate paper type screen displayed in this manner. The candidate paper type screen in Figure 17 is displayed in process S6 of Figure 9. To allow the measurement of the back side to be instructed in process S7, the candidate paper type screen in Figure 17 is provided with a "Automatic Sheet Identification and Back Side Measurement" button. When this button is selected, it is determined that the back side will be measured in process S7. The word "Recommended" is displayed for the paper type that best matches the measurement results from the mechanical property measurement unit 102 and the surface property measurement unit 103.

[0066] In the case of double-sided measurement, the control unit 400 identifies the paper type based on the surface properties information (adjacent pixel difference integrated value and brightness) of the front and back surfaces, similar to the case of single-sided measurement. Since the basis weight measurement is detected from the ultrasonic transmittance, there is no difference in the measurement value between the front and back surfaces. Similarly, there is no difference in the measurement value for paper thickness between the front and back surfaces. For this reason, the average value of the respective measurement values ​​is used for basis weight and paper thickness.

[0067] The control unit 400 identifies the paper type based on the measurement results (feature quantities) of the front (first side) and back (second side). The control unit 400 classifies the type of sheet P based on the measurement results of the surface properties of the front and back sides of sheet P (S21). The control unit 400 selects from the paper type database 402 a brand in which the sheet information for the first surface property matches the measurement results (surface property information) of the front, and the sheet information for the second surface property matches the measurement results (surface property information) of the back. The brand selected at this time is designated as the "first brand". The user may have mistakenly inserted the front and back sides of sheet P when measuring it. Therefore, the control unit 400 selects from the paper type database 402 a brand in which the sheet information for the first surface property matches the measurement results (surface property information) of the back, and the sheet information for the second surface property matches the measurement results (surface property information) of the front (second brand). In this way, the type of sheet P is classified.

[0068] The control unit 400 selects a paper type from the classification based on surface properties (first type and second type) that falls within a predetermined range of the measured basis weight (e.g., ±5 [gsm]) (S22). Furthermore, the control unit 400 selects a paper type from the selected type that falls within a predetermined range of the measured paper thickness (e.g., ±5 [μm]) (S23). The control unit 400 displays the selected sheet type candidates on the display of the operation unit 502 (S24). By using basis weight and paper thickness as parameters for paper type selection in addition to surface property information, the accuracy of paper type identification is improved.

[0069] Figure 18 is an example of the candidate paper type screen displayed in this manner. The candidate paper type screen in Figure 18 is displayed in the process of S10 in Figure 9. In case the paper type the user wants to select is not among the candidate paper types, the candidate paper type screen in Figure 18 is provided with a "Automatic Sheet Identification and Remeasurement" button. When this button is selected, the process in Figure 9 is executed again. The word "Recommended" is displayed for the paper type that best matches the measurement results from the mechanical property measurement unit 102 and the surface property measurement unit 103.

[0070] As described above, the paper type identification device 100 of this embodiment notifies the user to flip over the sheet P and insert the other side once the user has inserted the sheet P and one side has been measured. By measuring the back side, it is possible to prevent false detection of brand classification due to the influence of differences in the feature quantities of the two sides.

[0071] In this embodiment, the paper type identification device 100 is equipped with an information processing unit 160 that processes the measurement results from the mechanical property measurement unit 102 and the surface property measurement unit 103 and transmits them to the control unit 400 of the image forming apparatus 201. However, the processing of these measurement results may also be performed directly by the control unit 400. In this case, the functions of the information processing unit 160 would be included in the control unit 400. Alternatively, the paper type identification device 100 would transmit the measurement results from the mechanical property measurement unit 102 and the surface property measurement unit 103 directly to the control unit 400.

[0072] In this embodiment, the image forming apparatus 201 is equipped with the paper type database 402, but the paper type identification device 100 may be equipped with the paper type database 402. In this case, the information processing unit 160 of the paper type identification device 100 will perform the identification of the paper type of sheet P, which is performed by the control unit 400. Furthermore, although an example has been described in which sheet detection by the upstream sheet sensor 104 is used as the trigger, it is also possible to use sheet detection by the downstream sheet sensor 105 as the trigger. In this case, surface quality measurement is performed when sheet P is withdrawn from the paper type identification device 100. Instead of the downstream sheet sensor 105, the encoder rotation of the paper thickness sensor 140 may be detected, and the reading interval by the surface quality measurement unit 103 may be determined based on that timing.

[0073] The above describes an example in which the operating conditions (control parameters) of the image forming apparatus 201 are determined by selecting the sheet category and sheet brand from the features detected by the paper type identification device 100. The paper type identification device 100 may also be a paper physical property measuring device, and the control parameters may be determined directly from the measured sheet features. In addition, the paper type database 402 and the control unit 400 may be located on the cloud. In that case, if the image forming apparatus 201 is connected to the cloud via a network, the latest paper type setting information and identification algorithm can always be selected.

Claims

1. A reading sensor that reads the surface of the sheet, The system includes a control means that controls the reading sensor to read the first surface of the sheet and obtain a first reading result, controls the reading sensor to read a second surface of the sheet different from the first surface and obtain a second reading result, and identifies the type of sheet based on the first reading result and the second reading result. The control means performs a first mode in which the type of sheet is determined based on the first reading result and the second reading result, and a second mode in which the type of sheet is determined based on the first reading result. The control means is characterized by receiving user instruction information that instructs the execution of the first mode, and selecting the first mode based on the received user instruction information. Paper type identification device.

2. A reading sensor that reads the surface of the sheet, Control means for controlling the reading sensor to read the first surface of the sheet and obtain a first reading result, controlling the reading sensor to read a second surface of the sheet different from the first surface and obtain a second reading result, and identifying the type of the sheet based on the first reading result and the second reading result, Equipped with a display, The control means performs a first mode in which the type of sheet is determined based on the first reading result and the second reading result, and a second mode in which the type of sheet is determined based on the first reading result. The display is characterized by displaying a screen that allows the user to select whether or not to execute the first mode after the reading sensor has read the first surface of the sheet. Paper type identification device.

3. The system is further characterized by comprising a display that shows the type of the sheet, The paper type identification device according to claim 1.

4. The display is characterized in that it displays the type of the sheet. The paper type identification device according to claim 2.

5. The control means is characterized in that, in the first mode, after the reading sensor has read the first surface of the sheet, it outputs a notification prompting the reading sensor to read the second surface of the sheet. The paper type identification device according to claim 1 or 2.

6. The control means, in the second mode, is characterized in that, after the reading sensor has read the first surface of the sheet, it determines the type of sheet based on the first reading result without prompting the reading of the second surface of the sheet. The paper type identification device according to claim 1 or 2.

7. The control means is characterized by receiving user instruction information that instructs the execution of the first mode, and selecting the first mode based on the received user instruction information. The paper type identification device according to claim 2.

8. The system further includes a display that shows a screen on which the user can select whether or not to execute the first mode, The display is characterized in that it displays the screen after the reading sensor has read the first surface of the sheet. The paper type identification device according to claim 1.

9. The system further includes a sheet sensor positioned downstream of the reading sensor in the insertion direction in which the sheet is inserted from the opening, which detects the presence or absence of the sheet. The control means is characterized in that, after the sheet sensor detects the sheet, it controls the reading sensor to obtain the first reading result of the first surface of the sheet that has been read. The paper type identification device according to claim 1 or 2.

10. An image forming apparatus that forms an image on a sheet based on image forming conditions, A reading sensor that reads the surface of the sheet, Control means for controlling the reading sensor to read the first surface of the sheet and obtain a first reading result, controlling the reading sensor to read a second surface of the sheet different from the first surface and obtain a second reading result, and controlling the image formation conditions based on the first reading result and the second reading result, Equipped with a display, The control means executes a first mode in which a plurality of candidates for the type of sheet are displayed on the display based on the first reading result and the second reading result, and a second mode in which the plurality of candidates for the type of sheet are displayed on the display based on the first reading result. The control means is characterized in that, upon receiving user instruction information that instructs the execution of the first mode, it selects the first mode based on the user instruction information. Image forming apparatus.

11. An image forming apparatus that forms an image on a sheet based on image forming conditions, A reading sensor that reads the surface of the sheet, Control means for controlling the reading sensor to read the first surface of the sheet and obtain a first reading result, controlling the reading sensor to read a second surface of the sheet different from the first surface and obtain a second reading result, and controlling the image formation conditions based on the first reading result and the second reading result, Equipped with a display, The control means executes a first mode in which a plurality of candidates for the type of sheet are displayed on the display based on the first reading result and the second reading result, and a second mode in which the plurality of candidates for the type of sheet are displayed on the display based on the first reading result. The control means is characterized in that, after the reading sensor has read the first surface of the sheet, it displays a selection screen on the display that allows the user to choose whether or not to execute the first mode. Image forming apparatus.

12. The control means is characterized in that, after the reading sensor has read the first surface of the sheet, it displays a message on the display prompting the reader to read the second surface of the sheet. The image forming apparatus according to claim 10 or 11.

13. The control means is characterized by controlling the image forming conditions based on the type of sheet selected from the plurality of candidates displayed on the display. The image forming apparatus according to claim 10 or 11.

14. The control means is characterized in that, in the first mode, after the reading sensor has read the first surface of the sheet, it displays a message on the display prompting the reader to read the second surface of the sheet. The image forming apparatus according to claim 10 or 11.

15. The control means is characterized in that, in the second mode, after the reading sensor reads the first surface of the sheet, it does not display a message prompting the reader to read the second surface of the sheet, but instead displays a plurality of candidate sheet types on the display based on the first surface read by the reading sensor. The image forming apparatus according to claim 10 or 11.

16. When the control means receives user instruction information instructing the execution of the first mode, The first mode is selected based on the user instruction information. The image forming apparatus according to claim 11.

17. The control means is characterized in that, after the reading sensor has read the first surface of the sheet, it displays a selection screen on the display that allows the user to choose whether or not to execute the first mode. The image forming apparatus according to claim 10.

18. The system further includes a sheet sensor positioned downstream of the reading sensor in the insertion direction in which the sheet is inserted from the opening, which detects the presence or absence of the sheet. The control means is characterized in that, after the sheet sensor detects the sheet, it controls the reading sensor to obtain the first reading result of the first surface of the sheet that has been read. The image forming apparatus according to claim 10 or 11.

Images