Paper detection device, paper conveying device and image forming device

Abstract

The present invention detects paper thickness with high precision. The paper detection device (18) comprises: a paper thickness detection unit (70) including a reference component (71b) and a displacement sensor (759), which detects the paper thickness of the recording medium by making the reference component contact with the recording medium while applying force to the recording medium being transported, and using the displacement sensor to detect the height position of the reference component that changes according to the recording medium; a first mounting unit (182a) on which the paper thickness detection unit is mounted; a transport component (186) that clamps and transports the recording medium and is arranged adjacent to the paper thickness detection unit at a distance less than the length of the transported recording medium in the transport direction of the recording medium; and a displacement prevention unit (182b) that prevents the output of the displacement sensor from changing due to the relative height position of the reference component shifting according to whether the transport component clamps the recording medium when the paper thickness detection unit detects the paper thickness.

Description

Technical Field

[0001] The invention relates to a paper detection device, a paper conveying device and an image forming device. Background Art

[0002] In recent years, image forming devices such as electrophotographic printers have been widely used in the color printing industry. In the field of PP (production printing) corresponding to the color printing industry, it is required to adapt to a variety of papers compared to those used in offices. In addition, in order to perform high-quality printing on these various papers, there is an image forming device that sets the characteristics of the paper stored in the paper feed tray in multiple items and performs printing under image forming conditions corresponding to the set items.

[0003] In order to set such a variety of paper, there is a sheet thickness detection device that automatically detects the thickness of the paper as a characteristic of the paper used for printing. For example, in the sheet thickness detection device disclosed in Patent Document 1, a driven roller is supported so as to be displaceable relative to a driving roller, and a displacement sensor is used to detect the displacement amount of the first driven roller shaft supporting the two driven rollers in the paper thickness direction, thereby detecting the thickness of the paper.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2015-13719

[0005] However, Patent Document 1 only focuses on the dimensional tolerance of the roller diameter, and does not consider the influence of the roller located on the upstream side or downstream side of the paper thickness detection unit. Summary of the invention

[0006] The present invention has been completed in view of the above situation, and its purpose is to provide a paper detection device that can prevent the accuracy of paper thickness detection from being reduced due to the influence of conveying components located upstream or downstream, and can perform high-precision paper thickness detection, a paper conveying device equipped with the paper detection device, and an image forming device.

[0007] The above object of the present invention is achieved by the following means.

[0008] (1) A paper detection device comprises: a paper thickness detection unit including a reference member and a displacement sensor, wherein the paper thickness detection unit detects the paper thickness of the recording medium by causing the reference member to contact the recording medium while applying force to the recording medium, and using the displacement sensor to detect the height position of the reference member that changes according to the recording medium; a first mounting unit on which the paper thickness detection unit is mounted; a conveying member that clamps and conveys the recording medium and is arranged adjacent to the paper thickness detection unit at a predetermined interval less than the length of the recording medium being conveyed in the conveying direction of the recording medium; and a displacement prevention unit that prevents a change in the output of the displacement sensor caused by a relative height position of the reference member shifting depending on whether the conveying member clamps the recording medium when the paper thickness detection unit detects the paper thickness.

[0009] (2) According to the paper detection device described in (1) above, the above-mentioned conveying component is a conveying roller pair that clamps and conveys the recording medium, and the above-mentioned paper thickness detection part has a roller pair consisting of a first roller and a second roller that clamp and convey the recording medium in the roller gap, and relative to the above-mentioned first roller, the rotation axis of the above-mentioned second roller is supported by the above-mentioned first mounting part so as to be movable in the thickness direction of the above-mentioned recording medium, and the above-mentioned second roller is the above-mentioned reference component.

[0010] (3) According to the paper detection device described in (2) above, the predetermined interval between the paper thickness detection section and the conveying member is longer than a length of an outer circumference of the second roller.

[0011] (4) According to any one of (1) to (3) above, the transport member is mounted on a second mounting portion, the second mounting portion is the displacement prevention portion, and the first mounting portion and the second mounting portion are independent.

[0012] (5) According to the paper detection device described in any one of the above (1) to (3), the above-mentioned conveying component is installed on the above-mentioned first mounting portion, and in the area between the mounting position of the above-mentioned conveying component and the mounting position of the above-mentioned paper thickness detection portion in the above-mentioned first mounting portion, a hole or a slit or a thin-walled portion with a thin plate thickness is formed to reduce rigidity compared with other areas, thereby serving as the above-mentioned displacement prevention portion.

[0013] (6) In the paper detection device described in any one of (1) to (3), the conveying component is installed on the first mounting portion, and the first mounting portion is displaced due to the recording medium passing through the conveying component, thereby causing the height of the reference component installed on the same first mounting portion to shift, and the displacement prevention portion is a control portion, and the control portion controls the period during which the paper thickness detection portion detects the paper thickness according to the timing of the recording medium passing through the conveying component.

[0014] (7) According to the paper detection device described in (6), the control unit sets a period during which the paper thickness detection unit detects the paper thickness to a period excluding a timing when the recording medium passes through the transport member.

[0015] (8) According to the paper detection device described in (2) above, the paper detection device includes a control unit, and the control unit predicts the life of the paper thickness detection unit or determines abnormality based on the output change of the displacement sensor corresponding to the rotation period of the conveying roller pair.

[0016] (9) According to the paper detection device described in (8) above, the outer diameter of the first roller is different from the outer diameter of the second roller, and the control unit distinguishes the roller that causes the output variation based on the cycle of the output variation to predict the life or determine the abnormality.

[0017] (10) A paper conveying device comprising: a paper supply tray for accommodating a plurality of recording media; a conveying unit for conveying the recording medium from the paper supply tray and conveying it along a conveying path; and a paper detection device as described in any one of (1) to (9) above, for detecting the thickness of the recording medium conveyed in the conveying path.

[0018] (11) An image forming apparatus comprising: the paper transport device according to (10) above; and an image forming unit that forms an image on a recording medium transported by the paper transport device.

[0019] The paper detection device of the present invention comprises: a paper thickness detection unit including a reference member and a displacement sensor, which detects the paper thickness of the recording medium by making the reference member contact the recording medium while applying force to the recording medium being transported, and detecting the height position of the reference member that changes according to the recording medium using the displacement sensor; a first mounting unit on which the paper thickness detection unit is mounted; a transport member that clamps and transports the recording medium and is arranged adjacent to the paper thickness detection unit at a distance less than the length of the recording medium being transported in the transport direction of the recording medium; and a displacement prevention unit that prevents the output of the displacement sensor from changing due to the relative height position of the reference member shifting according to whether the transport member clamps the recording medium when the paper thickness detection unit detects the paper thickness. Thus, a paper detection device capable of measuring the paper thickness with high accuracy, a paper transport device having the paper detection device, and an image forming device can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing a schematic configuration of an image forming apparatus including a paper detection device according to the present embodiment.

[0021] Figure 2 It is a block diagram showing the structure of the image forming apparatus.

[0022] Figure 3 It is a cross-sectional view showing a schematic structure of a paper detection device arranged in a conveyance path.

[0023] Figure 4 It is a perspective view showing the structure of a basis weight detection section and a surface property detection section.

[0024] Figure 5 It is a cross-sectional schematic diagram showing a schematic structure of a basis weight detection section.

[0025] Figure 6 It is a cross-sectional schematic diagram showing a schematic structure of a surface property detection unit.

[0026] Figure 7 It is a cross-sectional schematic diagram showing a schematic structure of a paper thickness detection section.

[0027] Figure 8 It is a top view of the paper thickness detection unit.

[0028] Fig. 9 It is a perspective view showing the internal structure of the paper thickness detection section.

[0029] Fig.10 It is a perspective view showing the internal structure of the paper thickness detection section.

[0030] Fig.11 This is a diagram for explaining a displacement sensor.

[0031] Fig.12 This is a diagram for explaining the change in output of the paper thickness detection unit at each paper conveyance position.

[0032] Fig.13 This is a diagram for explaining the change in output of the paper thickness detection unit at each paper conveyance position.

[0033] Fig.14 This is a diagram for explaining the relationship between whether or not the downstream transport roller pair holds the paper and the output change of the displacement sensor.

[0034] Fig.15 This is a flowchart showing the paper thickness detection process (first displacement preventing section) by the paper detection device according to the first embodiment.

[0035] Fig.16 This is a flowchart showing the printing process of the image forming apparatus.

[0036] Fig.17 It is a diagram showing the structure of a second displacement preventing section of the paper detection device according to the second embodiment.

[0037] Fig.18 It is a diagram showing the structure of a third displacement preventing unit of the paper detection device according to the third embodiment.

[0038] Fig.19 It is a diagram showing the structure of a fourth displacement preventing unit of a paper detection device according to a modified example of the third embodiment.

[0039] Fig. 20 This is a flowchart showing a roller life prediction or abnormality determination process according to the fourth embodiment.

[0040] Description of reference numerals: 1...image forming device; 10...image forming device body; 11...control unit; 12...storage unit; 13...image forming unit; 14...paper conveying unit; 141, 142...paper feeding tray; 143, 144...conveying path; 15...operation panel; 18...paper detecting device; 181...lower guide plate; 182, 182a, 182c, 182d...upper guide plate (first mounting portion); 182b...upper guide plate (second mounting portion); 185...roller urging portion; 185a...metal plate; 185b...shaft support portion; 185c...elastic spring; 186...conveying roller pair; 186a...lower roller; 186b...upper roller; 40...pressing mechanism; 50...basic weight detecting section; 60...surface property detecting section; 70...paper thickness detecting section; 71...conveying roller pair; 71a...lower roller (first roller); 71b...upper roller (second roller) (reference component); 75...sensor unit; 751...roller force metal plate; 752...sensor mounting section; 759...displacement sensor; 91...detection rod; 92...support section; 93...support section mounting section; 78...spring; 20...paper supply unit; 24...paper supply conveying section. DETAILED DESCRIPTION

[0041] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the accompanying drawings, the same elements are marked with the same figure marks, and repeated descriptions are omitted. In addition, for the sake of convenience of explanation, the dimensional ratios of the drawings are exaggerated and sometimes different from the actual ratios. In the accompanying drawings, the up and down direction is set as the Z direction, the front and back directions of the image forming device are set as the X direction, and the direction orthogonal to these X and Z directions is set as the Y direction. The X direction is also called the width direction or the rotation axis direction. In addition, around the paper detection device (the paper detection device 18 described later), the conveying direction of the recording medium parallel to the plane of the conveying path (the conveying path 143 described later) inclined relative to the horizontal plane and orthogonal to the X direction is called the Y' direction, and the direction orthogonal thereto is called the Z' direction (refer to Figure 3etc.). In addition, the XY' plane is a plane parallel to the conveying surface, and Z' is a direction perpendicular to the conveying surface. In the present embodiment, the recording medium includes printing paper (hereinafter referred to as paper) and various films. In particular, the paper includes paper made from plant-derived mechanical pulp and / or chemical pulp. In addition, the types of recording media include glossy paper and matte paper of coated paper, and ordinary paper and high-quality paper of uncoated paper.

[0042] Figure 1 1 is a diagram showing a schematic structure of an image forming apparatus 1 including a paper detection device 18. Figure 1 As shown, the image forming apparatus 1 includes an image forming apparatus main body 10 and a paper feeding unit 20 which are mechanically and electrically connected to each other.

[0043] (Image Forming Apparatus Main Body 10)

[0044] The image forming apparatus body 10 includes a control unit 11 , a storage unit 12 , an image forming unit 13 , a paper feeding unit 14 , an operation panel 15 , a paper detection device 18 , a communication unit (not shown), etc. These are connected to each other via a signal line such as a bus for exchanging signals. Figure 3 143 is a side view showing the structure of the paper detection device 18 disposed in the conveying path 143. The paper detection device 18 is also called a medium sensor, and is composed of a pressing mechanism 40 (see Figure 3 , Figure 4 ), a basic weight detection unit 50, a surface property detection unit 60, and a paper thickness detection unit 70 to measure paper properties. The basic weight detection unit 50 is a first optical sensor of a transmission type, and the surface property detection unit 60 is a second optical sensor of a reflection type. The pressing mechanism 40 presses the paper when the surface property detection unit 60 detects the paper properties. The details of the paper detection device 18 will be described later.

[0045] (Control Unit 11)

[0046] The control unit 11 is composed of a CPU, a ROM, a RAM, etc., and executes various processes by executing programs stored in the ROM and a storage unit 12 described later, and controls various parts of the device and performs various calculation processes according to the programs. The control unit 11 functions as a determination unit that determines the type of paper based on the detection results of the two optical sensors or the paper detection device 18 including the optical sensors.

[0047] (Storage Unit 12)

[0048] The storage unit 12 is composed of auxiliary storage units such as a ROM that stores various programs or various data in advance, a RAM that temporarily stores programs or data as a working area, and a hard disk that stores various programs or various data. In addition, the storage unit 12 stores paper information stored in each paper supply tray. The paper information includes information such as the type of paper, size (paper width, paper length), basis weight (weight), and paper type (coated paper, ordinary paper, high-quality paper, rough paper, etc.), which is set by the paper type determination process described later. In addition, the storage unit 12 can also store a learned model and paper file (both described later) used for determining the paper type or paper type.

[0049] (Image Forming Unit 13)

[0050] The image forming unit 13 forms an image by, for example, electrophotography. Figure 1 As shown in FIG. 1 , the image forming unit 13 includes a writing unit 131 corresponding to the basic colors of Y (yellow), M (magenta), C (cyan), and K (black), a photosensitive drum 132, and a developer 133 storing a two-component developer composed of toners of the respective colors and a carrier. In addition, the image forming unit 13 also includes an intermediate transfer belt 134, a secondary transfer unit 135, and a fixing unit 136. The toner images formed on the photosensitive drum 132 by the developers 133 of the respective colors are superimposed on the intermediate transfer belt 134, and are transferred to the conveyed paper 300 in the secondary transfer unit 135. The toner images on the paper 300 are fixed on the paper 300 by heating and pressurizing the fixing unit 136 on the downstream side.

[0051] (Paper feeding and conveying unit 14)

[0052] The paper feed conveying unit 14 includes a plurality of paper feed trays 141, 142, conveying paths 143, 144, etc. The conveying paths 143, 144 include: a plurality of conveying roller pairs arranged along these conveying paths, and a driving motor (not shown) for driving these conveying roller pairs. A delivery roller is provided to deliver the topmost paper of the plurality of papers 300 stacked and placed in the paper feed trays 141, 142, and deliver the papers 300 in the paper feed trays one by one to the conveying path on the downstream side. A paper detection device 18 is arranged on the upstream side of the positioning roller on the conveying path 143. As shown in FIG. Figure 3 As shown in FIG. 1 , in the vicinity of the paper detection device 18, the conveying path 143 is formed between guides composed of metal plates or the like which are opposed to each other at a predetermined interval. The guide plate includes upper and lower guide plates 181 to 184 (see the following description). Figure 3 ). The paper 300 passes through the conveying path 143.

[0053] The paper feed conveying unit 14 conveys the paper 300 fed from the paper feed tray 141 or the like. After the image is formed on the paper 300 conveyed in the conveying path 143 by the image forming unit 13, the paper 300 is discharged to the paper discharge tray 145. In the case of double-sided printing in which an image is formed on the back side of the paper 300, the paper 300 with the image formed on one side is conveyed to the conveying path 144 for double-sided image formation located at the lower part of the apparatus body. The paper 300 conveyed to the conveying path 144 is reversed in the switchback path, and then merged with the conveying path 143 for single side, and the image is formed on the other side of the paper 300 again by the image forming unit 13.

[0054] (Operation panel 15)

[0055] The operation panel 15 includes a touch panel, numeric keys, a start button, a stop button, etc., and displays the status of the image forming device body 10 or the image forming device 1, the life information of the roller (replacement timing), etc., and is used for inputting settings and instructions from the user regarding the type of paper loaded on the paper feed tray 141, etc.

[0056] (Paper feeding unit 20)

[0057] like Figure 1 As shown, the paper supply unit 20 includes a paper supply conveying unit 24. In addition to the paper supply conveying unit 24, the paper supply unit 20 also includes a control unit, a storage unit, and a communication unit (not shown) for communicating with the image forming apparatus main body 10, which are connected to each other via a signal line such as a bus for exchanging signals. The paper supply conveying unit 24 includes a plurality of paper supply trays 241, 242, 243 and a conveying path 244. The paper 300 conveyed from each paper supply tray is conveyed to the image forming apparatus main body 10 on the downstream side, and the paper characteristics are measured by the paper detection device 18, or the image is formed by the image forming unit 13.

[0058] (Paper detection device 18)

[0059] As described above, the paper detection device 18 is composed of the pressing mechanism 40, the basic weight detection unit 50, the surface property detection unit 60, and the paper thickness detection unit 70. Figure 3 As shown in FIG. 1 , among these components, a paper thickness detection unit 70 is arranged on the upstream side in the conveying direction, and a pressing mechanism 40, a basis weight detection unit 50, and a surface property detection unit 60 are arranged on the downstream side. The lower guide plate 181 and the upper guide plate 182 are opposed to each other at a predetermined interval, and the lower guide plate 183 and the upper guide plate 184 are opposed to each other at a predetermined interval, and a conveying path 143 is formed between these opposed guide plates. On the conveying path 143, conveying roller pairs 71, 186, and 187 are arranged in order from the upstream side. The details of the structure of the paper thickness detection unit 70 will be described later.

[0060] Figure 4 is a perspective view showing the structure of the basis weight detection unit 50 and the surface property detection unit 60. Figure 3 , Figure 4 As shown, the basic weight detection unit 50 and the surface property detection unit 60 are arranged along the X direction (width direction) between the conveying roller pairs 186 and 187. In addition, a pressing mechanism 40 is arranged below the surface property detection unit 60 (on the negative side of the Z' direction). The pressing mechanism 40 is arranged below the lower guide plate 183. The pressing mechanism 40 includes a pressing unit, a drive motor, a cam mechanism, etc. The upper surface of the pressing unit is a plane parallel to the lower guide plate 183 and moves up and down by the drive motor. Normally, it is substantially the same surface as the lower guide plate 183, but it rises during measurement to press the paper 300 toward the surface property detection unit 60 side.

[0061] like Figure 4 As shown, a part of the basic weight detection section 50 (light receiving section) and the entirety of the surface property detection section 60 are arranged above the upper guide plate 184 .

[0062] (Basic weight detection unit 50)

[0063] Figure 5 : is a schematic diagram showing the structure of the basic weight detection unit 50. The basic weight detection unit 50 is a transmissive optical sensor for detecting the basic weight of the paper 300, and includes a light emitting unit and a light receiving unit, and measures the attenuation amount (transmittance) of light transmitted through the paper 300.

[0064] like Figure 5 As shown, the basic weight detection unit 50 includes a plurality of light emitting units 51 and a light receiving unit 52. The light emitting unit 51 includes a first light emitting unit 51a, a second light emitting unit 51b and a third light emitting unit 51c. The first, second and third irradiation lights are irradiated to the irradiation area from the first, second and third light emitting units, respectively. The irradiation area (second irradiation area) is the inner area in the opening a12 when viewed from the Z' direction. The opening a12 is provided on the upper guide plate 184. In addition, an opening a22 is also provided on the lower guide plate 183 at a position opposite to the opening a12. The openings a11 and a12 are of the same shape, for example, a rectangle. In order to prevent foreign matter such as paper dust from the paper 300 passing through the conveying path 143 from adhering to the openings a12 and a22, transparent sheets 54a and 54b made of PET or the like, which transmit the wavelengths of each irradiation light, are installed in the openings a12 and a22. In addition, the opening a11 (refer to Figure 6 ) No sheet is installed, and when not measuring, a baffle (not shown) is closed to prevent foreign matter from adhering.

[0065] The first light emitting unit 51a irradiates a first irradiation light having a first wavelength. The first wavelength is, for example, a wavelength of near infrared light longer than the wavelength of visible light. The second light emitting unit 51b irradiates a second irradiation light having a second wavelength. The second wavelength is, for example, a wavelength of blue light included in the visible light. The first light emitting unit 51a and the second light emitting unit 51b are both arranged on the opposite side of the light receiving unit 52 relative to the conveying path 143, and the third light emitting unit 51c is arranged on the same side as the light receiving unit 52, near the light receiving unit 52. The third light emitting unit 51c irradiates a third irradiation light having a third wavelength toward the irradiation area (opening a12). The third wavelength is, for example, the wavelength of green light in the visible light.

[0066] The third irradiation light is irradiated toward the conveying path 143 in the upper and lower guide plates 183 and 184. A reflecting portion 53 is provided on the inner side of the lower guide plate 183 disposed near the first light emitting portion 51a and the second light emitting portion 51b. The reflecting portion 53 is painted with, for example, green, the same color as the third irradiation light, and reflects the third irradiation light. In addition, the reflecting portion 53 does not reflect the first irradiation light (near infrared light) and the second irradiation light (blue light) which are not of the same color.

[0067] In the present embodiment, the control unit 11 controls the first light emitting unit 51a and the second light emitting unit 51b to irradiate the first irradiation light and the second irradiation light at different timings, respectively. The light receiving unit 52 receives the first irradiation light and the second irradiation light, detects the light amount of each irradiation light, and outputs the detected light amount of the first irradiation light and the second irradiation light to the control unit 11. In addition, the first irradiation light and the second irradiation light are also irradiated to the paper 300 transported to the position of the opening a12. The light receiving unit 52 receives the transmitted light (first transmitted light and second transmitted light) of the first irradiation light and the second irradiation light, detects the light amount of each irradiation light, and outputs the detected light amount of the first transmitted light and the second transmitted light to the control unit 11. That is, the light receiving unit 52 detects the first irradiation light and the second irradiation light when there is no paper 300, and the first transmitted light and the second transmitted light when the paper 300 is located at the opening a12.

[0068] Similarly, regarding the third light emitting unit 51 c , the light receiving unit 52 detects the first reflected light reflected by the reflecting unit 53 when there is no paper 300 and the second reflected light reflected by the surface of the paper 300 when the paper 300 is located at the opening a12 .

[0069] The control unit 11 calculates the first transmittance by dividing the amount of the first transmitted light by the amount of the first irradiated light. Similarly, the control unit 11 calculates the second transmittance by dividing the amount of the second transmitted light by the amount of the second irradiated light. The type of the paper 300 is determined based on the first and second transmittances and the determination criteria stored in the storage unit 12.

[0070] In addition to the first and second transmittances, the control unit 11 may also divide the amount of the second reflected light by the amount of the first reflected light to calculate the reflectance, and determine the type of the paper 300 in consideration of the reflectance. In addition, in this embodiment, the third light emitting unit 51c and the reflecting unit 53 are provided, but they may be omitted.

[0071] (Surface property detection unit 60)

[0072] Next, with Figure 3 , Figure 4 Refer to Figure 6 , the structure of the surface property detection unit 60 is described. Figure 6 is a cross-sectional view of the surface property detection unit 60 .

[0073] As shown in these figures, the surface property detection unit 60 includes a housing 61, a light emitting unit 62, a collimating lens 63, and a plurality of light receiving units 64 (light receiving units 641, 642). In addition, the surface property detection unit 60 also includes a baffle and an opening and closing mechanism of the baffle (both not shown). The housing 61 covers other structural elements and blocks external light.

[0074] like Figure 6 As shown, the configuration angle of the light emitting unit 62 is set so that the incident angle of the irradiation light relative to the reference plane is 75°. The incident angle of 75° is an angle used in the glossiness measurement of white paper according to JIS, and is an angle that is less affected by the color of the object to be measured. The reference plane is an imaginary plane including the lower surface of the upper guide plate 184. During the measurement, the surface of the paper 300 as the object to be measured is arranged on the reference plane. The light emitting unit 62 is arranged on the substrate b1. The light emitting unit 62 includes a light emitting element such as an LED that emits light of a specified wavelength as a light source. The irradiation light emitted from the light source (point light source) becomes approximately parallel light through the collimating lens 63 and irradiates the irradiation area. In this embodiment, the wavelength of the light source as the light emitting unit 62 is preferably in the range of more than 405nm and less than 525nm, and the most preferred wavelength is around 465nm. The irradiation area (first irradiation area) is the inner area in the opening a11 when observed from the Z' direction, and the center (optical axis) of the irradiation area intersects with the reference plane parallel to the XY' plane at the intersection point p1. As the light emitting unit 62 , a surface-emitting LED or a cannonball-shaped LED may be used.

[0075] The multiple light receiving parts 64 respectively include light receiving elements such as photodiodes and phototransistors, including: a first light receiving part 64 (light receiving part 641) that receives regular reflected light from the irradiated area, and one or more second light receiving parts 64 (light receiving part 642) that receive diffuse reflected light from the irradiated area. The first light receiving part 641 is arranged at a position of a reflection angle of 75° corresponding to an incident angle of 75° of the light emitting part 62, and receives regular reflected light. In addition, the second light receiving part 642 can be arranged at any reflection angle except for the position of 75° in the range of a reflection angle of more than 0° and less than 90°, and receives diffuse reflected light. As the configuration position, the reflection angles are preferably 60°, 30°, and 0°, and more preferably two positions of 60° and 30°, or one position of 60°. In Figure 6 In the example of FIG. 1 , a first light receiving unit 641 for receiving regular reflected light with a reflection angle of 75° and a second light receiving unit 642 for receiving diffuse reflected light with a reflection angle of 30° are shown. In these figures, the light receiving unit 641 is arranged on the substrate b2, and the light receiving unit 642 is arranged on the substrate b3.

[0076] (Paper thickness detection unit and conveying unit)

[0077] Next, refer to Figure 7 to Figure 11 , the structure of the paper thickness detection unit 70 is described. Figure 7 is a schematic cross-sectional view showing a schematic structure of a paper thickness detection unit. Figure 8 , Fig. 9 They are respectively a plan view and a perspective view of the paper thickness detection unit 70 . Fig.10 It is a perspective view showing the internal structure around the displacement sensor 759 of the paper thickness detection unit 70 .

[0078] (Conveying parts)

[0079] As shown in these figures, the paper thickness detection unit 70 includes a conveying roller pair 71 and a sensor unit 75. In addition, a conveying roller pair 186 is arranged adjacent to the downstream side of the paper thickness detection unit 70 in the conveying direction. The paper thickness detection unit 70 and the conveying roller pair 186 are both mounted on an upper guide plate 182. Specifically, the upper roller 186b of the conveying roller pair 186 is mounted on the upper guide plate 182 through a roller force applying unit 185. The main metal plate 185a of the roller force applying unit 185 is screwed to the upper guide plate 182, and the roller shaft of the upper roller 186b is supported by a shaft support unit 185b provided on the upper guide plate 182 so as to be movable in the Z' direction. In addition, the roller shaft of the upper roller 186b is urged toward the lower roller 186a by two springs 185c provided on both end sides. One end of each spring 185c is mounted on the main metal plate 185a, and the other end abuts against the roller shaft of the upper roller 186b. Here, the upper guide plate 182 and the conveying roller pair 186 correspond to the "first mounting portion" and the "conveying member arranged adjacent to the paper thickness detecting portion 70", respectively. That is, the conveying roller pair 186 as the conveying member is mounted on the upper guide plate 182 as the first mounting portion through the main metal plate 185a of the roller urging portion 185 and the shaft support portion 185b.

[0080] (Paper Thickness Detection Unit 70)

[0081] One of the two rollers of the conveying roller pair 71 is a fixed (axial center fixed) driving roller, and the other is a driven roller that can be forced to move away from or approach the driving roller. In this embodiment, the upper roller 71b of the conveying roller pair 71 is a driven roller (second roller), and the lower roller 71a is a driving roller (first roller) that is rotated by a driving source (not shown). Each roller 71a, 71b includes a plurality of (two) rollers arranged at a predetermined interval in the axial direction. Figure 7 , Figure 8 As shown in the figures, the sensor unit 75 is composed of a roller force metal plate 751, a sensor mounting portion 752, a roller shaft 76, a shaft support portion 77, a spring 78, and a displacement sensor 759. The displacement sensor 759 includes a detection rod 91, a support portion 92, and a support portion mounting portion 93. The support portion mounting portion 93 of the displacement sensor 759 is mounted on the roller force metal plate 751 via the sensor mounting portion 752.

[0082] Mainly as Fig.10 As shown, the axial directions of the lower roller 71a and the upper roller 71b are arranged parallel to the width direction of the transported paper 300. The upper roller 71b is rotatably supported by a cylindrical roller shaft 76.

[0083] The roller shaft 76 of the upper roller 71b is movably supported by the shaft support portion 77 provided on the upper guide plate 182. The upper roller 71b functions as a reference member, and conveys the paper 300 through the roller gap formed between the upper roller 71b and the lower roller 71a, and the height position is displaced by the thickness of the paper 300. The height position is detected by the displacement sensor 759 as described later.

[0084] The shaft support portion 77 and the upper guide plate 182 are formed by bending a metal plate. In addition, the rotation of the roller shaft 76 is limited by a rotation limiting member such as a bearing (not shown). A support hole 77a is formed in the shaft support portion 77 for inserting the roller shaft 76. The support hole 77a is a long hole extending in the thickness direction by a predetermined length. In addition, the roller shaft 76 is supported so as to be able to slide in the thickness direction along the support hole 77a of the shaft support portion 77.

[0085] In addition, the length of the opening in the conveying direction of the support hole 77a is set to be longer than the diameter of the roller shaft 76. Therefore, a small gap is formed between the roller shaft 76 and the support hole 77a in the conveying direction. Moreover, the roller shaft 76 is supported by the shaft support portion 77 via the support hole 77a so as to be movable by a predetermined length in the conveying direction.

[0086] In addition, the roller shaft 76 is biased toward the lower roller 71a by two springs 78 disposed at both ends. Fig. 9 , Fig.10 As shown, one end of each spring 78 is attached to the roller urging metal plate 751, and the other end is in contact with the roller shaft 76. The upper roller 71b supported by the roller shaft 76 is urged toward the lower roller 71a by the spring 78. And, when the lower roller 71a is driven to rotate, the upper roller 71b also rotates together with the lower roller 71a.

[0087] The spring 78 as the urging member is, for example, a compression coil spring. However, the urging member is not limited to the compression coil spring, and other various elastic members such as a leaf spring and rubber may also be applied.

[0088] The roller shaft 76 has a flat surface 76a formed by partially cutting out the outer periphery in the axial direction. The detection rod 91 of the displacement sensor 759 contacts the flat surface 76a. The displacement sensor 759 includes the detection rod 91 contacting the roller shaft 76 and the support portion 92 supporting the detection rod 91.

[0089] Fig.11 759 is a diagram for explaining the displacement sensor 759. Fig.10 , Fig.11As shown in (a), the abutting surface 91b of the detection rod 91 that abuts against the roller shaft 76 is formed into a roughly arc shape. The detection rod 91 is supported by the support portion 92 via the rotation shaft 91a so as to be rotatable. Moreover, if the roller shaft 76 moves in the thickness direction (Z' direction) corresponding to the thickness of the paper 300 clamped by the conveying roller pair 71, the detection rod 91 rotates around the support portion 92. In the displacement sensor 759, the disk portion 91c of the detection rod 91 and the transmission type optical sensor S1 function as encoders to detect the thickness of the paper 300 according to the rotation angle of the detection rod 91. Fig.11 (b) is an output example of a two-phase encoder used in the displacement sensor 759, which detects the position displacement (thickness) in the Z' direction with an accuracy of several microns.

[0090] In this example, the thickness of the paper 300 is detected based on the rotation angle of the detection lever 91, but the present invention is not limited thereto. As the displacement sensor 759, a measuring device or other various components that detect the displacement of the roller 76 in the thickness direction may be used.

[0091] In addition, the example in which the roller shaft 76 is used as the displacement member and the detection rod 91 is brought into contact with the roller shaft 76 is described, but the present invention is not limited thereto. For example, a linkage member that is displaced in the conveying direction and the thickness direction together with the roller shaft 76 may be used as the displacement member. Furthermore, the displacement sensor 759 may also bring the detection rod 91 into contact with the linkage member and detect the displacement amount of the upper roller 71b in the thickness direction based on the displacement amount of the linkage member.

[0092] Here, the paper thickness detection unit 70 is mounted on the upper guide plate 182 as the first mounting portion via the roller force metal plate 751 and the shaft support portion 77. Specifically, the "roller force metal plate 751" of the paper thickness detection unit 70 is screwed to the upper guide plate 182, the sensor mounting portion 752 is screwed to the roller force metal plate 751, and the displacement sensor 759 is fixed to the sensor mounting portion 752 via a buckle and a screw. In addition, the upper roller 71b is mounted on the upper guide plate 182 via the "roller force metal plate 751" and the "shaft support portion 77".

[0093] (Change in Output of the Displacement Sensor 759 of the Paper Thickness Detection Section 70 of the First Embodiment)

[0094] As described above, the paper thickness detection unit 70 and the transport roller pair 186 (transport member) disposed adjacent thereto and clamping the paper are mounted on the same upper guide plate 182 (first mounting portion). As a result, as described below, the relative height position between the displacement sensor 759 of the paper thickness detection unit 70 and the upper roller 71b (reference member) is displaced according to whether the transport roller pair 186 clamps the paper 300, thereby changing the output of the displacement sensor 759.

[0095] Fig.12 , Fig.13 3 is a diagram for explaining the output change of the paper thickness detection unit 70 at each conveyance position of the paper 300. Fig.14 This is a diagram for explaining the relationship between whether or not the downstream transport roller pair 186 holds the paper and the output change of the displacement sensor.

[0096] exist Fig.12 At time t0 (position 0) shown in (a) of FIG. 8 , the paper 300 conveyed from the paper feed tray 141 or the like through the conveyance path 143 has not yet reached the paper thickness detection unit 70 .

[0097] In the next Fig.12 At time t1 (position 1) shown in (b), the paper 300 reaches the paper thickness detection unit 70, and its front end is clamped by the roller gap of the conveying roller pair 71. In this state, the height position of the upper roller 71b is displaced upward by the thickness of the paper 300, and the displacement of the height position is detected by the displacement sensor 759. In addition, the control unit 11 may maintain the output of the displacement sensor 759 at time t0, and use this output as a reference to calculate the displacement amount (i.e., the thickness of the paper) at time t1.

[0098] In the next Fig.12 At time t2 (position 2) shown in (c), the paper 300 is located between the paper thickness detection unit 70 and the downstream conveying roller pair 186.

[0099] In the next Fig.13 At time t3 (position 3) shown in (d), the paper 300 reaches the paper thickness detection unit 70 and the conveying roller pair 186 on the downstream side. In this state, the upper roller 186b receives an upward force (F1) corresponding to the thickness of the paper 300 and is displaced. Due to the influence of this displacement, the upper guide plate 182 is deformed via the roller force applying unit 185. At this time, the upper guide plate 182 is in a slightly floating state. The influence of the deformation of the upper guide plate 182 acts on the sensor unit 75 as an upward force (F2) via the roller force applying metal plate 751, and by this force, the height position of the entire sensor unit 75 including the displacement sensor 759 (except the upper roller 71b) is shifted upward. On the other hand, the upper roller 71b remains in a state of being applied toward the paper 300, so the height does not change. According to such a situation, since the relative positional relationship between the upper roller 71b (reference member) and the displacement sensor 759 is displaced, the output changes (error detection on the thinner side).

[0100] In the next Fig.13At time t4 (position 4) shown in (e), the paper 300 separates from the paper thickness detection unit 70 and the conveying roller pair 186, the deformation of the upper guide plate 182 is eliminated, the height displacement of the sensor unit 75 returns, and the output of the displacement sensor 759 returns to its normal original state.

[0101] exist Fig.14 In the figure, the horizontal axis is the roller feed amount, which corresponds to the rotation angle of the upper roller 71b. Fig.12 (c) corresponds to position 2, 180 degrees with Fig.13 The vertical axis is the output of the displacement sensor 759 converted into length (paper thickness), and the thickness of the paper 300 used in the test is the ideal value of the horizontal dotted line. The triangle in the legend is obtained by removing the conveying roller pair 186 on the downstream side through the experiment, and the circle indicates Fig.12 , Fig.13 As shown in FIG. 1 , the output when the downstream conveying roller pair 186 is present. Thus, it is found that the output variation (error) of about 50 to 80 μm occurs depending on whether the downstream conveying roller pair 186 clamps the paper 300 or not.

[0102] Here, the distance between the paper thickness detection unit 70 and the conveying roller pair 186, more specifically, the distance in the conveying direction between the roller gap of the conveying roller pair 71 and the roller gap of the conveying roller pair 186 will be described. This distance L is shorter than the length of the minimum size (e.g., a standard postcard, B6, etc.) that can form an image in the image forming device 1, and is longer than the length of the outer circumference of the roller 71b. The reason why it is longer than the minimum size is that the paper is conveyed by adjacent rollers. In addition, the reason why it is longer than the outer circumference is that in order to reduce the influence of the error of the outer diameter (diameter) of the roller 71b, the paper thickness is continuously detected corresponding to the length of one circumference of the roller 71b, and the obtained measured values ​​are averaged.

[0103] (Paper thickness detection processing)

[0104] Fig.15 1 is a flowchart showing a paper thickness detection process by the paper detection device 18 according to the first embodiment. In the first embodiment described below, the control unit 11 that controls the paper detection device 18 functions as a first displacement preventing unit.

[0105] (Step S101)

[0106] The control unit 11 controls the paper feeding and conveying unit 14 to convey paper 300 of a specific object of paper characteristics from the paper feeding tray 141. If a mode for measuring a plurality of paper 300 or a mode for measuring the paper characteristics of the paper 300 while continuously forming an image is set, the paper 300 is continuously conveyed from the paper feeding tray 141 with a predetermined paper interval.

[0107] (Step S102)

[0108] It is determined whether the paper has reached the roller pair 71 of the paper thickness detection unit 70. If it has reached (yes), the process proceeds to step S103. This determination can be made based on the sensor S2 (see FIG. 14 ) configured in the conveying path 143 for detecting the presence of paper. Fig.12 etc.), or by the output of a sensor arranged on the upstream side of the sensor S2 in the conveying path 143.

[0109] (Step S103)

[0110] The control unit 11 reads the output of the displacement sensor 759 and obtains the measured value. At this time, in order to reduce the influence of the outer diameter error of the roller 71b, it is preferable to continue the measurement a plurality of times at a predetermined cycle.

[0111] (Step S104)

[0112] If the paper 300 reaches the downstream conveying roller pair 186 (Yes), the process proceeds to step S105. This determination can be made by determining that a predetermined time has passed since the output of the sensor S2 changed. This state is equivalent to Fig.13 (d) position 3.

[0113] (Step S105)

[0114] The control unit 11 ends the paper thickness detection and detects the paper thickness based on the measurement value obtained in step S103. For example, the paper thickness is detected by averaging the measurement values ​​obtained during one rotation of the roller 71b.

[0115] (Step S106)

[0116] The control unit 11 is set to the continuous measurement mode, and if the next sheet is measured (Yes), the process proceeds to step S107. On the other hand, if it is not (No), the process ends (End).

[0117] (Step S107)

[0118] It is determined whether the paper 300 has passed through the downstream conveying roller pair 186. If so, the process returns to step S102 and the subsequent processes are repeated. Fig.13 The position of (e) is 4.

[0119] Thus, in the present embodiment, a displacement prevention unit is provided, which prevents the output of the displacement sensor from changing due to the relative height position of the reference member being displaced according to the presence or absence of the conveying member clamping the recording medium when the paper thickness detection unit 70 detects the paper thickness. In particular, in the first embodiment, the control unit 11 as the displacement prevention unit controls the period during which the paper thickness detection unit 70 detects the paper thickness according to the timing of the recording medium passing through the roller gap of the conveying roller pair 186 (conveying member). More specifically, the period is set to a period other than the timing of the recording medium passing through the roller gap of the conveying roller pair 186. For example, as a period other than the timing of passing, it is from after the paper 300 arrives at the conveying roller pair 71 to immediately before the paper 300 arrives at the conveying roller pair 186 on the downstream side. Alternatively, in the case of measuring while continuously conveying the paper, it is from after the previous paper leaves the conveying roller pair 186 to immediately before the next subsequent paper arrives at the conveying roller pair 186. According to the paper detection device of the first embodiment, the relative height position of the reference member is shifted according to whether the transport member clamps the recording medium, which can prevent the output of the displacement sensor from changing, thereby preventing a decrease in accuracy and measuring the paper thickness with high accuracy.

[0120] (Print Processing)

[0121] Next, the above Fig.15 The printing process including the paper type determination process and the paper thickness detection process is described. Fig.16 1 is a flowchart showing a printing process performed in the image forming apparatus 1 .

[0122] (Step S10)

[0123] The user operates the paper setting button on the operation screen (not shown) displayed on the operation panel 15. The control unit 11 starts paper setting by accepting the operation from the user. The start instruction of the paper setting includes selection information of one or more paper feed trays (paper feed trays 141, 142, 241 to 243) loaded with the target paper. The paper setting process performs the following processing. (1) The paper characteristics are measured by the paper detection device 18. The measured paper characteristics include the basic weight, surface properties and paper thickness based on the basic weight detection unit 50, the surface property detection unit 60 and the paper thickness detection unit 70. Among them, the paper characteristics measured by the basic weight detection unit 50, the surface property detection unit 60 and the paper thickness detection unit 70 are as follows: Fig.15The processing shown is used to execute the paper thickness based on the paper thickness detection unit 70. In addition, the control unit 11 performs paper type determination and basis weight distinction determination based on the measured values ​​of basis weight, surface properties, and paper thickness. This determination can be performed based on rules, using a learned model (paper type discrimination engine) and a paper file to perform paper type determination and basis weight distinction determination. Here, the "paper file" refers to, for a certain paper, the measured value of the paper detection device 18 and the characteristic data input by the user, the paper size, and an arbitrary identification name (such as paper variety) are pre-registered in correspondence. The "paper type discrimination engine" is also called a learned model, which refers to a learned model generated by teacher learning using teacher data, using the detection output of the paper detection device 18 of the paper 300 as an input value and the paper type information of the paper 300 set by the user as a correct answer label.

[0124] (Step S20)

[0125] When the paper setting is completed, the image forming conditions are set to match the set paper characteristics, and test printing (trial printing) of the print job is performed.

[0126] (Step S30)

[0127] If the test printing result is not satisfactory, or if multiple types of paper are used in one print job, the user repeats step S10 and subsequent processing for other paper (step S30: No). On the other hand, if the test printing result is satisfactory and the confirmation related to all paper types is completed (Yes), the control unit 11 enters the processing into step S40 by accepting the user's operation of preparation completion.

[0128] (Step S40)

[0129] The control unit 11 controls the image forming unit 13 and the like to execute the print job (main printing) and complete the print process (end).

[0130] Thus, in the image forming apparatus 1 of this embodiment, the type of paper (recording medium) is determined using the detection result from the paper detection device 18. Thus, the paper type can be determined accurately and image forming conditions corresponding thereto can be set, thereby outputting high-quality prints.

[0131] (Second Embodiment)

[0132] exist Figure 7 to Figure 14In the first embodiment shown, the paper thickness detection unit 70 and the transport roller pair 186 (transport member) disposed adjacent thereto and clamping the paper are mounted on the same upper guide plate 182 (first mounting portion). Therefore, the deformation of the first mounting portion caused by the presence or absence of paper clamping by the transport roller pair 186 causes the relative height position between the displacement sensor 759 of the paper thickness detection unit 70 and the reference member (roller 71b) to shift. In the second embodiment described below, the first mounting portion is not deformed according to the presence or absence of paper clamping by the transport roller pair 186.

[0133] Fig.17 1 is a diagram showing the structure of the second displacement preventing portion of the paper detection device 18 according to the second embodiment. In the second embodiment, the second displacement preventing portion is a second mounting portion which is independent of the first mounting portion and whose deformation does not affect the first mounting portion.

[0134] Specifically, if Fig.17 As shown, the conveying roller pair 186 is mounted on the upper guide plate 182b as the second mounting portion, and the paper thickness detection portion 70 is mounted on the upper guide plate 182a as the first mounting portion. A cutout (gap) is provided between the first and second mounting portions, and the two are independent. The first and second mounting portions are both mounted on the housing of the image forming apparatus main body 10. In addition, Fig.17 In order to facilitate observation, each guide plate ( Fig.18 , Fig.19 Same as above).

[0135] The force of deformation of the second mounting portion caused by the paper clamping of the conveying roller pair 186 is not transmitted to the first mounting portion, and does not affect the measurement of the paper thickness detection unit 70. In this way, the same effect as the first embodiment is obtained. In addition, in the second embodiment, the sensor output can be obtained during the entire period when the paper 300 is clamped by the conveying roller pair 71, and the paper thickness can be measured with higher accuracy.

[0136] (Third Embodiment)

[0137] In the second embodiment, a gap is provided between the first mounting portion where the paper thickness detection portion 70 is mounted and the second mounting portion where the conveying roller pair 186 is mounted, so that the deformation force is not transmitted. In the third embodiment, the paper thickness detection portion 70 and the conveying roller pair 186 are mounted on the same first mounting portion (one upper guide plate 182c), but a hole or a rectangular elongated slit for making the rigidity lower than other regions is provided in the area between the mounting position where the paper thickness detection portion 70 is mounted and the mounting position where the conveying roller pair 186 is mounted in the first mounting portion as a third deformation prevention portion.

[0138] Specifically, if Fig.18As shown, an upper guide plate 181c provided with a slit-shaped hole h1 is used. By providing the hole h1 in this way, the rigidity of the upper guide plate 181c becomes low, and the force of deformation of the first mounting portion caused by the gripping of the paper by the conveying roller pair 186 is not easily transmitted to the paper thickness detection unit 70, and the measurement of the paper thickness detection unit 70 is almost not affected. In this way, the same effect as the second embodiment is obtained.

[0139] Fig.19 2 is a diagram showing the structure of the fourth displacement prevention portion of the paper detection device according to a modified example of the third embodiment. Fig.19 The fourth displacement prevention portion shown in FIG. 1 is composed of a plurality of holes h2. In addition, a thin-walled portion that reduces the thickness of the metal plate may be formed in place of or in addition to the holes or slits. In such a modified example, the same effect as the second embodiment is obtained.

[0140] (Roller life prediction or abnormality determination processing)

[0141] Fig. 20 This is a flowchart showing a roller life prediction or abnormality determination process according to the fourth embodiment. Fig. 20 The treatment shown is the same as Fig.15 The processing performed in parallel with the processing of may be performed when the paper thickness detection unit 70 measures the paper thickness, or may be performed during a period when paper is not being conveyed, for example, during an initial sequence when the power of the image forming apparatus 1 is turned on.

[0142] (Step S301)

[0143] The control unit 11 reads the output of the displacement sensor 759. This output is obtained while the roller rotates for at least several turns, and more than a dozen pieces of measurement data are obtained per one rotation.

[0144] (Step S302)

[0145] The control unit 11 extracts the periodic variation by performing frequency analysis on the measurement data acquired in step S301 by processing such as fast Fourier transform. At this time, data having a frequency that is extremely large or extremely small compared to the rotation period of the roller may be removed.

[0146] (Step S303)

[0147] The control unit 11 determines whether the period variation is greater than a predetermined amount. If there is no period variation greater than a predetermined amount (No), the process ends (End). On the other hand, if there is a period variation greater than a predetermined amount, the process proceeds to step S304.

[0148] (Step S304)

[0149] The control unit 11 compares the period with a period variation of a predetermined amount or more with the rotation period calculated from the outer circumference of each roller (roller 71a, 71b) of the paper thickness detection unit 70 stored in the storage unit 12, and extracts rollers with the same period.

[0150] (Step S305)

[0151] The control unit 11 compares the current period variation with the initial period variation, and performs a life prediction until the determination reference value is exceeded according to the increase ratio or increase amount of the period variation, and outputs the result to the operation panel 15 or the like. Alternatively, the output data is sent to a management server connected via a network. This determination is performed for each roller. In addition, in the present embodiment, the outer diameters of the rollers 71a and 71b are set to different values ​​from each other to a degree that the periods can be separated.

[0152] Here, the initial period variation refers to the period variation when each component is new and is stored in advance in the storage unit 12. For example, when the new image forming apparatus 1 is used, or when the service personnel replace the components, the history management data is reset, and each component can be determined to be new. Alternatively, when the variation exceeds the determination reference value, an abnormality determination is performed, and the result is displayed and output to the operation panel 15, or sent to the server.

[0153] Thus, in the fourth embodiment, the life of the paper thickness detection unit is predicted or abnormality is determined based on the output variation of the displacement sensor corresponding to the rotation period of the conveying roller pair, thereby preventing the paper detection device from being able to accurately detect the paper thickness and obtain a correct measurement value.

[0154] Regarding the structure of the image forming apparatus 1 having the paper detection device 18 (media sensor) described above, when describing the features of the above-mentioned embodiment, the main structure is described, and it is not limited to the above-mentioned structure, and various changes can be made within the scope of the claims. In addition, the structure of a general image forming apparatus is not excluded.

[0155] For example, in Figure 3 , 7 , etc. show an example in which the conveying roller pair 186 that is excluded from the influence on the output change of the displacement sensor 759 is arranged on the downstream side of the paper thickness detection unit 70, but the invention is not limited thereto and may be arranged on the upstream side or on both the upstream side and the downstream side. For example, there is a case in which the conveying roller pair on the downstream side is installed on the first installation portion (guide plate 182) on which the paper thickness detection unit 70 is installed.

[0156] In addition, in the paper thickness detection unit 70, an example of using a roller (upper roller 71b) as a reference component is shown, but it is not limited to this. It is also possible to make a component on a plane contact with the surface of the paper while applying force to the surface of the paper, and use a displacement sensor to measure the height of the component displaced according to the paper thickness, thereby measuring the paper thickness.

[0157] Furthermore, an example is shown in which the control unit 11 has a learned model, but the invention is not limited thereto. The learned model may be stored on a server connected to the image forming apparatus 1 via a network, and the server may be used to perform paper type determination. In this case, the image forming apparatus body 10 sends the data of the measured paper characteristics to the server, and the server that receives the data determines the paper type based on the data, and returns the determination result to the image forming apparatus. Figure 1 In the figure, the image forming apparatus 1 is connected to the optional paper feeding unit 20, but the image forming apparatus 1 may be a single unit without these options, or may be connected to another post-processing apparatus for performing post-processing on the paper on which the image is formed using the image forming apparatus main body 10.

Claims

1. A paper detection device, comprising: a paper thickness detection unit including a reference member and a displacement sensor, wherein the paper thickness detection unit detects the paper thickness of the recording medium by making the reference member contact the recording medium while applying force to the recording medium being conveyed, and detecting the height position of the reference member that changes according to the recording medium using the displacement sensor; A first mounting portion, on which the paper thickness detection portion is mounted; a conveying member that grips and conveys the recording medium, and is disposed adjacent to the paper thickness detection unit at a predetermined interval equal to or less than the length of the conveyed recording medium in a conveying direction of the recording medium; and a displacement preventing section for preventing a change in the output of the displacement sensor caused by a relative height position between the displacement sensor and the reference member being shifted according to the presence or absence of the recording medium being clamped by the conveying member when the paper thickness detecting section detects the paper thickness, The conveying component is installed on the first installation portion, In the first mounting portion, a region between the mounting position of the transport member and the mounting position of the paper thickness detector is formed with a hole, a slit, or a thin-walled portion as the displacement preventing portion in order to reduce rigidity compared with other regions.

2. The paper detection device according to claim 1, wherein: The conveying member is a conveying roller pair that clamps and conveys the recording medium. The paper thickness detection unit includes a roller pair consisting of a first roller and a second roller that clamp and convey the recording medium in a roller gap, wherein the rotation axis of the second roller is supported by the first mounting unit to be movable in the thickness direction of the recording medium relative to the first roller. The second roller is the reference member.

3. The paper detection device according to claim 2, wherein: The predetermined interval between the paper thickness detection portion and the transport member is longer than a length of an outer circumference of the second roller.

4. The paper detection device according to claim 2, wherein: The paper detection device includes a control unit configured to predict the life of the paper thickness detection unit or determine an abnormality based on a change in output of the displacement sensor corresponding to a rotation period of the transport roller pair.

5. The paper detection device according to claim 4, wherein: The outer diameter of the first roller is different from the outer diameter of the second roller, and the control unit distinguishes the roller causing the output fluctuation based on the cycle of the output fluctuation to predict the life or determine the abnormality.

6. A paper detection device, comprising: a paper thickness detection unit including a reference member and a displacement sensor, wherein the paper thickness detection unit detects the paper thickness of the recording medium by making the reference member contact the recording medium while applying force to the recording medium being conveyed, and detecting the height position of the reference member that changes according to the recording medium using the displacement sensor; A first mounting portion, on which the paper thickness detection portion is mounted; a conveying member that grips and conveys the recording medium, and is disposed adjacent to the paper thickness detection unit at a predetermined interval equal to or less than the length of the conveyed recording medium in a conveying direction of the recording medium; and a displacement preventing section for preventing a change in the output of the displacement sensor caused by a relative height position between the displacement sensor and the reference member being shifted according to the presence or absence of the recording medium being clamped by the conveying member when the paper thickness detecting section detects the paper thickness, The conveying component is installed on the first installation portion, The first mounting portion is displaced due to the recording medium passing through the conveying member, so that the height of the reference member mounted on the same first mounting portion is displaced. The displacement preventing part is a control part, The control unit controls a period during which the paper thickness detection unit detects the paper thickness, based on a timing at which the recording medium passes through the transport member.

7. The paper detection device according to claim 6, wherein: The conveying member is a conveying roller pair that clamps and conveys the recording medium. The paper thickness detection unit includes a roller pair consisting of a first roller and a second roller that clamp and convey the recording medium in a roller gap, wherein the rotation axis of the second roller is supported by the first mounting unit to be movable in the thickness direction of the recording medium relative to the first roller. The second roller is the reference member.

8. The paper detection device according to claim 7, wherein: The predetermined interval between the paper thickness detection portion and the transport member is longer than a length of an outer circumference of the second roller.

9. The paper detection device according to claim 6, wherein: The control unit sets a period during which the paper thickness detection unit detects the paper thickness to a period excluding a timing at which the recording medium passes through the transport member.

10. The paper detection device according to claim 7, wherein: The control unit predicts the life of the paper thickness detection unit or determines an abnormality based on a change in output of the displacement sensor corresponding to a rotation period of the transport roller pair.

11. The paper detection device according to claim 10, wherein: The outer diameter of the first roller is different from the outer diameter of the second roller, and the control unit distinguishes the roller causing the output fluctuation based on the cycle of the output fluctuation to predict the life or determine the abnormality.

12. A paper conveying device, comprising: A paper feed tray for storing multiple recording media; a conveying unit that conveys the recording medium from the paper feed tray and conveys it along a conveying path; and The paper detection device according to any one of claims 1 to 11 detects the thickness of the recording medium transported in the transport path.

13. An image forming device comprising: The paper conveying device according to claim 12; and The image forming unit forms an image on the recording medium transported by the paper transport device.

Images