Image forming device

Abstract

To accurately detect a value related to a content of water in a recording material to control an image forming condition.SOLUTION: An image forming apparatus comprises: light emitting means that emits light with a first wavelength and light with a second wavelength different from the first wavelength; light receiving means that receives the light with the first wavelength and the light with the second wavelength emitted by the light emitting means on an opposite side of the light emitting means with respect to a conveyance path; control means that controls an image forming condition in forming an image on a recording material on the basis of, the quantity of the light with the first wavelength and the quantity of the light with the second wavelength transmitting through the recording material and received by the light receiving means; and a rotating body that presses the recording material conveyed on the conveyance path. The rotating body includes two columnar members that are arranged at different positions in a direction orthogonal to a conveyance direction of the recording material and press the recording material, and a connection member that includes a rotation axis of the rotating body and connects the two columnar members with each other. When seen from a direction of the rotation axis, a light path of light connecting the light emitting means and the light receiving means with each other overlaps the two columnar members and does not overlap the connection member.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus that controls image forming conditions based on a value related to the moisture content of a recording material. [Background technology]

[0002] In an electrophotographic image forming apparatus such as a copying machine or a laser printer, a toner image formed on an image carrier is transferred to a recording material, and the recording material to which the toner image has been transferred is heated and pressurized to fix the toner image to the recording material. Transfer conditions such as a transfer bias, and fixing conditions such as a fixing temperature during fixing and a conveying speed of the recording material are controlled according to the size and type of the recording material. One of the parameters that must be considered in setting image forming conditions such as transfer conditions and fixing conditions is the amount of moisture contained in the recording material. The amount of moisture contained in the recording material varies depending on the installation environment of the image forming apparatus and the storage conditions of the recording material. Therefore, for example, it is possible to estimate the amount of moisture contained in the recording material based on the humidity detected by a humidity sensor provided in the image forming apparatus. However, since the estimation of the amount of moisture based on humidity does not detect the amount of moisture contained in each recording material individually, it may be significantly different from the amount of moisture actually contained in the recording material. In this case, the image forming conditions set will not be appropriate, and image defects will occur, or problems will occur in conveying the recording material due to deformation of the recording material.

[0003] For this reason, Patent Documents 1 to 3 disclose configurations for detecting the amount of moisture contained in each recording material. Patent Documents 1 to 3 disclose configurations for detecting the amount of moisture in an object to be detected by irradiating the object with light in a wavelength range absorbed by water and light in a wavelength range not absorbed by water, and detecting the amount of moisture in the object based on the amount of reflected light, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-57513 A [Patent Document 2] Japanese Patent Application Publication No. 9-210902 [Patent Document 3] Japanese Patent Application Publication No. 9-61351 Summary of the Invention [Problem to be solved by the invention]

[0005] The recording material conveyed in the image forming apparatus may fluctuate in a direction perpendicular to the image forming surface, that is, flutter. If light is irradiated onto the recording material being conveyed while fluttering, the value relating to the moisture content of the recording material cannot be detected accurately due to the fluctuation of the image forming surface caused by the flutter.

[0006] The present invention provides an image forming apparatus that accurately detects a value relating to the amount of moisture contained in a recording material and controls image forming conditions. [Means for solving the problem]

[0007] According to one aspect of the present invention, an image forming apparatus includes an image forming unit that forms an image on a recording material, a conveying path for conveying the recording material toward the image forming unit, and a light source that emits light of a first wavelength. A first light emitting means for emitting and a second wavelength different from the first wavelength. Light Inject Second a light emitting means, No. 1 Light emitting means and the second light emitting means On the other hand, No. 1 The light of the first wavelength emitted by the light emitting means; The second light emitting means emits a light receiving means for receiving light of the second wavelength, and a control means for controlling image forming conditions when forming an image on the recording material based on an amount of light of the first wavelength received by the light receiving means and an amount of light of the second wavelength received by the recording material; before Pressing the recording material conveyed through the conveying path No. 1 A rotating body; a second rotating body that is disposed at a position different from the first rotating body in a direction of a rotation axis of the first rotating body and presses the recording material conveyed through the conveying path; The direction of the rotation axis To When I saw it, No. 1 An optical path connecting the light emitting means and the light receiving means and an optical path of light connecting the second light emitting means and the light receiving means overlaps with the first rotating body and the second rotating body, and the first light emitting means and the second light emitting means are disposed between the first rotating body and the second rotating body in a direction perpendicular to the conveying direction of the recording material. It is characterized by: Effect of the Invention

[0008] According to the present invention, the value relating to the amount of moisture contained in the recording material can be detected with high accuracy, and image forming conditions can be controlled. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus according to an embodiment. [Diagram 2] 1 is a perspective view of a moisture sensing device according to one embodiment. [Diagram 3] FIG. 1 is a diagram showing the configuration of a moisture detection device according to an embodiment. [Figure 4] FIG. 1 is a diagram showing the configuration of a moisture detection device according to an embodiment. [Diagram 5] FIG. 2 is a diagram illustrating the positional relationship of each component of the moisture detection device according to the embodiment. [Figure 6] 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment. [Figure 7] 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment. [Figure 8] FIG. 11 is a diagram showing determination information according to an embodiment. [Figure 9] 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment. [Figure 10] 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment. [Figure 11] FIG. 1 is a diagram showing the configuration of a moisture detection device according to an embodiment. [Figure 12] FIG. 1 is a diagram showing the configuration of a moisture detection device according to an embodiment. [Figure 13] 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are merely examples, and the present invention is not limited to the contents of the embodiments. In addition, in each of the following drawings, components that are not necessary for the description of the embodiments are omitted from the drawings.

[0011] First Embodiment FIG. 1 is a configuration diagram of an image forming apparatus 1 according to this embodiment. In the figure, the letters Y, M, C, and K at the end of the reference symbols indicate that the colors of the toner images formed by the corresponding members are yellow, magenta, cyan, and black, respectively. However, when it is not necessary to distinguish the colors, the reference symbols are used without the letters at the end of the reference symbols. The photoconductor 11 is an image carrier, and is rotated clockwise in the figure during image formation. The charging roller 12 charges the surface of the photoconductor 11, which is rotated, to a uniform potential. The exposure unit 13 exposes the charged surface of the photoconductor 11 to light to form an electrostatic latent image on the surface of the photoconductor 11. The development unit 14 has toner of a corresponding color, and attaches the toner to the electrostatic latent image of the photoconductor 11 by a development bias output by the development roller 15, thereby forming a toner image on the photoconductor 11. The primary transfer roller 16 outputs a primary transfer bias and transfers the toner image on the photoconductor 11 onto the intermediate transfer belt 17, which is driven to rotate in a counterclockwise direction. Note that a full-color toner image can be formed by transferring the toner images on the photoconductors 11 onto the intermediate transfer belt 17 in a superimposed manner.

[0012] The intermediate transfer belt 17 is stretched by a drive roller 18, a secondary transfer counter roller 20, and a tension roller 25, and is rotated in accordance with the rotation of the drive roller 18. As a result, the toner image transferred to the intermediate transfer belt 17 is transported to a position facing the secondary transfer roller 19. Meanwhile, the recording material P stored in the cassette 2 is transported to a position facing the secondary transfer roller 19 by a feed roller 4 and transport rollers 5 and 6 in accordance with the timing at which the toner image transferred to the intermediate transfer belt 17 is transported to the position facing the secondary transfer roller 19. The secondary transfer roller 19 outputs a secondary transfer bias to transfer the toner image of the intermediate transfer belt 17 to the recording material P. Note that the toner that is not transferred to the recording material P and remains on the intermediate transfer belt 17 is removed from the intermediate transfer belt 17 by a blade 35 of a cleaning device 36. The recording material P to which the toner image has been transferred is transported to a fixing unit 21. The fixing unit 21 heats and presses the recording material P to fix the toner image to the recording material P. When an image is formed on only one side of the recording material P, after the toner image is fixed, the recording material P is discharged to the discharge tray 26 by the discharge roller 22 and the switchback roller 27. On the other hand, when an image is formed on both sides of the recording material P, the recording material P is sent to the conveying path indicated by the dotted line in the figure by the reverse rotation of the switchback roller 27 and the switching of a flapper (not shown), and is conveyed again to the position facing the secondary transfer roller 19, where an image is formed on the other side.

[0013] The image forming apparatus 1 also includes a moisture detection device 30 that detects a value related to the moisture content of the recording material P (including the moisture content itself). The moisture detection device 30 is disposed downstream of the transport rollers 5 and 6 and upstream of the secondary transfer roller 19 in the transport direction of the recording material P. The moisture detection device 30 includes a light emitting section 31 and a light receiving section 32 disposed on the opposite side of the light emitting section 31 with respect to the transport path along which the recording material P is transported. The light emitting section 31 is held by the secondary transfer unit 23 together with the secondary transfer roller 19. The moisture detection device 30 also includes a pressing rotor, not shown in FIG. 1, for stably transporting the recording material.

[0014] The control unit 3 of the image forming apparatus 1 is a control unit for the entire image forming apparatus, and includes a CPU 80. The CPU 80 executes programs stored in a non-volatile memory (not shown) of the control unit 3, and controls the image forming apparatus using a RAM (not shown) as a work area. The control unit 3 also includes a setting control unit 40 that sets image forming conditions. The setting control unit 40 sets image forming conditions, such as transfer conditions and fixing conditions, when forming a toner image on the recording material P, based on a value related to the moisture content of the recording material P detected by the moisture detection device 30.

[0015] FIG. 2 is a perspective view showing the structure of the moisture detection device 30. The recording material P is transported in the direction indicated by the arrow T inside the moisture detection device 30, and a value related to the moisture content is detected during the transport process. As shown in FIG. 2, a pressing rotor 33 presses the recording material P transported on the transport path toward the transport path with a pressing force F by a biasing mechanism (not shown). The pressing rotor 33 is a driven roller that is rotated in the R direction by the recording material P. In other words, the recording material P is transported by the transport rollers 5 and 6 and the secondary transfer roller 19 while being sandwiched between the pressing rotor 33, and is configured to rotate by the transport of the recording material P. As a result, the recording material P is prevented from fluttering inside the moisture detection device 30 and is transported in a stable state.

[0016] FIG. 3 is a view of the moisture detection device 30 as viewed from the upstream side in the conveying direction of the recording material P. The light emitting section 31 has light emitting elements L1 and L2 that emit light of different wavelengths, for example, 560 nm and 850 nm, on an electric board EB1. The light receiving section 32 has a line light receiving element LS provided on an electric board EB2. The line light receiving element LS has a plurality of light receiving elements arranged in a line (linear) in a direction perpendicular to the conveying direction of the recording material P. The line light receiving element LS is arranged so as to be able to receive light emitted by the light emitting elements L1 and L2 that is transmitted through the recording material P, and each light receiving element of the line light receiving element outputs an electric signal according to the amount of light received. For each light receiving element included in the line light receiving element LS, an inexpensive element having light receiving sensitivity in the visible light and near infrared light region (approximately 400 to 1000 nm) including the emission wavelengths of the light emitting elements L1 and L2 can be used. Therefore, there is no need to use an expensive light receiving element made of InGaAs, which has light receiving sensitivity to the absorption wavelengths of water (1450 nm, 1940 nm, etc.). The pressing rotor 33 includes two cylindrical members 331 and 332 of the same diameter that press the recording material P, and a connecting member 333 that connects the cylindrical members 331 and 332. The pressing rotor 33 is made of a material that sufficiently transmits the wavelengths of light emitted by the light emitting elements L1 and L2, for example, a transparent material. The diameter of the connecting member 333 is shorter than the diameter of the cylindrical members 331 and 332. This is to prevent the connecting member 333 from directly contacting the glass surface that forms a part of the transport path of the recording material P, so that the connecting member 333 does not damage the glass surface. Here, the glass surface is provided at a position facing the connecting member 333 so that the light emitted from the light emitting elements L1 and L2 reaches the line light receiving element LS. By preventing the glass surface from being scratched, it is possible to prevent a decrease in the accuracy of moisture content detection, which will be described later.

[0017] Fig. 4 is a cross-sectional view taken along line AA in Fig. 3, and Fig. 5 is an explanatory diagram of the positional relationship of each component. As shown in Fig. 5, the light-emitting elements L1 and L2, the central axis of rotation of the pressing rotor 33, and the line light-receiving element Ls are arranged so as to be present in approximately the same plane (within the plane PI in Fig. 5, which corresponds to the vertical dashed line in Fig. 4). Also, as shown in Fig. 5, each component is arranged so that the three straight lines, namely the imaginary line La connecting the light-emitting elements L1 and L2, the central axis of rotation Lb of the pressing rotor 33, and the arrangement direction Lc of each element of the line light-receiving element LS, are parallel to each other and are within the plane PI. Furthermore, the distance L between the imaginary line La and the central axis of rotation Lb is a-b and the distance L between the rotation axis Lb and the straight line Lc b-c should be approximately equal.

[0018] Figures 6 and 7 show the state in which the light-emitting elements L1 and L2 are made to emit light. Note that Figures 6 and 7 are views seen from the same positions as Figures 3 and 4, respectively. In Figures 6 and 7, the light emitted by the light-emitting element L1 is indicated by L1L, and the light emitted by the light-emitting element L2 is indicated by L2L. As shown in Figure 6, the light L1L and the light L2L emitted by the light-emitting elements L1 and L2 reach the line light-receiving element LS with a spread in the direction perpendicular to the conveying direction of the recording material P. Then, based on the electrical signals output by each light-receiving element of the line light-receiving element LS, the received light amount of the light L1L and the received light amount of the light L2L can be determined.

[0019] The light L1L and L2L are attenuated by internal reflection and loss when passing through the transparent pressing rotor 33. Furthermore, the light L1L and L2L are greatly attenuated by transmission through the recording material P before reaching the line light receiving element LS. However, as shown in FIG. 7, the pressing rotor 33 having a circular cross section has a lens-like effect, and in the conveying direction of the recording material P, the light emitted by the light emitting elements L1 and L2 can be suppressed from spreading, and the light can be focused on the line light receiving element LS. In addition, the transparent pressing rotor 33 allows the line light receiving element LS to detect the amount of received light while holding the recording material P. Therefore, the influence of local deviations in the moisture content in the conveying direction of the recording material P can be suppressed, and the average moisture content within the surface of the recording material can be detected.

[0020] In the following, a description will be given of how to detect a value related to the amount of moisture (moisture content) contained in the recording material P based on the amount of light received of the first wavelength of 560 nm and the second wavelength of 850 nm different from the first wavelength. First, it is assumed that the light emission intensities of the light emitting element L1 and the light emitting element L2 are equal. Also, the amount of light emitted by the light emitting element L1 and transmitted through the recording material P is referred to as the first transmitted light amount, and the amount of light emitted by the light emitting element L2 and transmitted through the recording material P is referred to as the second transmitted light amount. At this time, the transmitted light amount difference, which is the difference between the first transmitted light amount and the second transmitted light amount, changes depending on the moisture content of the recording material P, as shown in FIG. 8. Note that FIG. 8 shows the case where the recording material P has a basis weight of 60 g / m2. 2 The figure shows the measurement results of the moisture content and the difference in the amount of transmitted light when using plain paper (60 g paper) of 100 g. The moisture content is the ratio (%) of the amount of moisture contained in the recording material P to the basis weight of the recording material P, and is a value related to the moisture content of the recording material P.

[0021] The reason why the difference in the amount of transmitted light changes depending on the moisture content of the recording material P will be described below. The amount of light transmitted through the recording material P is affected by both the change in the surface properties of the recording material P due to moisture absorption and the light absorption by the water contained in the recording material P. In other words, when the moisture content of the recording material P changes, the amount of transmitted light changes accordingly. However, the variation in the amount of transmitted light due to the change in the surface properties is not very wavelength-dependent, so the amount of variation in the amount of transmitted light due to the change in the surface properties associated with the change in the moisture content of the recording material P is almost the same regardless of the wavelength, and the difference in the amount of transmitted light hardly changes. On the other hand, the light absorption due to the moisture contained in the recording material P is wavelength-dependent, so the longer the wavelength, the greater the amount of light absorption. Therefore, the amount of variation in the amount of transmitted light due to the light absorption associated with the change in the moisture content of the recording material P differs depending on the wavelength, and the difference in the amount of transmitted light changes. Therefore, the variation in the amount of transmitted light due to the change in the moisture content of the recording material P is wavelength-dependent overall, so the difference changes depending on the moisture content of the recording material P.

[0022] In this embodiment, as shown in FIG. 8, the relationship between the moisture content and the difference in the amount of transmitted light is measured in advance, and the control unit 3 stores the determination information indicating the relationship between the moisture content and the difference in the amount of transmitted light. The control unit 3 then uses the determination information based on the difference in the amount of transmitted light between the light L1L and the light L2L to determine the moisture content of the recording material. The determination information may be determined for each basis weight of the recording material used in image formation. In this case, the image forming apparatus 1 determines the moisture content of the recording material based on the determination information corresponding to the basis weight of the recording material to be image formed. Next, a method of determining the first transmitted light amount and the second transmitted light amount will be described. For example, if the light emission intensities of the light emitting element L1 and the light emitting element L2 are equal and the light receiving sensitivity of each light receiving element of the line light receiving element LS is constant regardless of the wavelength, the first transmitted light amount and the second transmitted light amount can be determined as the received light amounts of the light L1L and the light L2L transmitted through the recording material P, respectively. However, in general, the light receiving sensitivity of each light receiving element of the line light receiving element LS is wavelength dependent, and the light emission intensity of the light emitting element L1 and the light emitting element L2 may not be equal. Therefore, first, the amount of light received of the light L1L detected by the line light receiving element LS without passing through the recording material P (hereinafter, the amount of light received without paper) is obtained. Next, the amount of light received of the light L1L detected by the line light receiving element LS when passing through the recording material P (hereinafter, the amount of light received with paper) is obtained. Then, the ratio of the amount of light received with paper to the amount of light received without paper is multiplied by an adjustment coefficient to obtain the amount of transmitted light of the light L1L, that is, the first transmitted light amount. The same applies to the second transmitted light amount. Here, the adjustment coefficient is a coefficient for correcting the difference between the sensitivity to the first wavelength and the sensitivity to the second wavelength of each element of the line light receiving element LS, and the difference in light emission intensity between the light emitting element L1 and the light emitting element L2.

[0023] As described above, in this embodiment, the recording material is pressed by the transparent pressing rotor 33 to suppress fluttering of the recording material. Then, the recording material is irradiated through this transparent pressing rotor 33, and a value related to the moisture content of the recording material is detected by the amount of light transmitted. Therefore, it is possible to suppress fluctuations in the amount of transmitted light due to fluttering of the recording material, and it is possible to accurately detect a value related to the moisture content of the recording material. Note that instead of forming the entire pressing rotor 33 from a transparent member, it is also possible to configure the pressing rotor 33 so that only the area through which the light L1L and L2L pass is made of a transparent member. Also, in this embodiment, it is possible to detect a value related to the moisture content of the recording material without using an expensive light receiving element having light receiving sensitivity to the absorption wavelength of water (1450 nm, 1940 nm, etc.). Note that the present invention can also be used to detect the moisture content using the absorption wavelength of water. Also, since the moisture content can be detected with high accuracy, it is possible to set image formation conditions suitable for the moisture content of each recording material. For example, the control unit 3 of the image forming apparatus can appropriately set transfer conditions such as a transfer voltage (transfer bias) and a transfer current when transferring an image to a recording material, based on the detected value related to the moisture content of the recording material. Also, the control unit 3 of the image forming apparatus can appropriately set fixing conditions such as a fixing temperature and a conveying speed of the recording material when fixing an image to the recording material, based on the detected value related to the moisture content of the recording material.

[0024] Second Embodiment Next, the second embodiment will be described with a focus on differences from the first embodiment. Figures 9 and 10 are diagrams of the moisture detection device 30 according to this embodiment, and correspond to Figures 6 and 7 of the first embodiment. The same components as those of the moisture detection device 30 of the first embodiment are given the same reference numerals, and their description will be omitted. In this embodiment, a pressing rotor 34 is used instead of the pressing rotor 33 of the first embodiment. As in the first embodiment, the pressing rotor 34 includes two cylindrical members 331 and 332 of the same diameter that press the recording material, and a connecting member 343 that connects the cylindrical members 331 and 332. The two cylindrical members 331 and 332 are disposed at different positions in a direction perpendicular to the conveying direction of the recording material, and the connecting member 343 is a member that extends in a direction perpendicular to the conveying direction of the recording material and includes the rotation axis of the pressing rotor 34. However, the thickness of the connecting member 343 is made thinner than the connecting member 333 of the first embodiment. In other words, the area of ​​the cross section perpendicular to the rotation axis of the connecting member 343 is made smaller than the area of ​​the cross section perpendicular to the rotation axis of the cylindrical members 331 and 332. Furthermore, in the first embodiment, the center of rotation of the pressing rotor 33 was located on the line connecting the light emitting elements L1 and L2 and the line light receiving element LS in the recording material transport direction. In this embodiment, as shown in Fig. 10, position 38 of the rotation center of the pressing rotor 34 in the recording material transport direction is shifted a predetermined distance from position 37 in the first embodiment to the upstream side in the recording material transport direction.

[0025] Therefore, the light L1L and L2L received by the line light receiving element LS is not light that has passed through the connecting member 343. As shown in FIG. 9, the light L1L and L2L received by the line light receiving element LS includes light that has passed through the cylindrical members 331 and 332. However, it is also possible to adjust the arrangement area of ​​the line light receiving element LS so that the line light receiving element LS receives only the light L1L and L2L that has not passed through the pressing rotor 34. This allows the line light receiving element LS to receive light that has been reduced in attenuation by the pressing rotor 34. Since the amount of light received by the line light receiving element LS is increased, the amount of moisture contained in the recording material P can be detected with high accuracy.

[0026] The amount of shift of the rotation center toward the upstream side in the recording material transport direction is determined within a range that can suppress fluttering of the recording material P in the optical path from the light emitting elements L1 and L2 to the line light receiving element LS. As an example, the amount of shift is 5 mm or less. Alternatively, as shown in Fig. 10, the rotation center of the pressing rotor can be shifted within a range in which a line connecting the light emitting elements L1 and L2 and the light receiving element LS passes through the cylindrical members 331 and 332. The direction in which the rotation center is shifted may also be toward the downstream side in the recording material transport direction.

[0027] As described above, the connection member 343 including the rotation axis of the pressing rotor 34 is arranged at a position where it does not interfere with the optical path from the light emitting elements L1 and L2 to the line light receiving element LS. This configuration suppresses the attenuation of light caused by the pressing rotor 34, and therefore makes it possible to accurately detect the value related to the moisture content of the recording material. Note that in this embodiment, the pressing rotor 34 does not have to be a transparent member.

[0028] <Third embodiment> Next, the third embodiment will be described with a focus on differences from the first embodiment. Figures 11 and 12 are diagrams of the moisture detection device according to this embodiment. Note that Figure 11 is a view from the upstream side of the conveying direction of the recording material P, and Figure 12 is a cross-sectional view taken along the line AA in Figure 11. Note that the same components as those described in the first embodiment are given the same reference numerals, and their description will be omitted. As shown in Figure 11, in this embodiment, the arrangement positions of the light-emitting elements L1 and L2 are shifted in a direction perpendicular to the conveying direction compared to the configuration of the first embodiment. In Figure 11, they are shifted to the right, but they may be shifted to the left. In addition, instead of the pressing rotor 33, a pressing rotor 36 composed of a transparent member 36A and a black member 36B (shaded portion) is used. The black member 36B is provided so as to be located on a side different from the side to which the light-emitting elements L1 and L2 are shifted. In addition, a light-emitting element L3 and a light guide LG that guides the light emitted by the light-emitting element L3 to the recording material P are provided on the same substrate as the line light-receiving element LS.

[0029] The light emitting element L3 and the light guide LG are provided to determine the surface quality of the recording material. The principle of determining the surface quality is described in, for example, JP 2014-114131 A. In brief, the light emitted by the light emitting element L3 irradiates the surface of the recording material P via the light guide LG, and the reflected light is received by the line light receiving element LS. There is a correlation between the degree of unevenness of the surface of the recording material P and the amount of reflected light. Therefore, a table showing the relationship between the degree of unevenness and the amount of reflected light is set in the image forming apparatus in advance, and the control unit 3 determines the surface quality of the recording material based on the table and the amount of light received by the line light receiving element LS of the reflected light of the light irradiated by the light emitting element L3.

[0030] FIG. 13 shows a state where the light emitting elements L1, L2, and L3 are emitting light, and corresponds to FIG. 6 of the first embodiment. The light emitted by the light emitting elements L1 and L2 is received by the line light receiving element LS through the transparent member 36A of the pressing rotary body 36, as in the first embodiment. However, in this embodiment, the light emitting elements L1 and L2 are shifted to the right in the figure, so that the light L1L and the light L2L are received by the light receiving element in the right half of the line light receiving element LS in the figure. On the other hand, the light emitted by the light emitting element L3 is irradiated from the lower side in the figure through the light guide LG to the surface of the recording material P. The light receiving element in the line light receiving element LS in an area different from the area that receives the light L1L and L2L receives the reflected light of the light emitted by the light emitting element L3. The black member 36B of the pressing rotary body 36 is located above the light receiving area of ​​the line light receiving element LS for the light emitted by the light emitting element L3. That is, the black member 36B of the pressing rotor 36 is disposed at a position facing the light receiving area of ​​the line light receiving element LS for receiving the light emitted by the light emitting element L3 with the recording material P interposed therebetween. The black member 36B transmits a weaker amount of light than the transparent member 36A. Therefore, this black member 36B can prevent the transmitted light emitted by the light emitting elements L1 and L2 from the recording material P and external light from entering the light receiving element of the line light receiving element LS that receives the reflected light of the light emitted by the light emitting element L3. This can prevent the accuracy of determining the surface property of the recording material P from deteriorating.

[0031] As described above, in this embodiment, the moisture detection device can be provided with a function for determining the surface properties of the recording material, eliminating the need to provide the image forming apparatus with a separate function for determining the surface properties of the recording material, and allowing the image forming layer to be made smaller.

[0032] [Other embodiments] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0033] 31: light emitting unit, 32: light receiving unit, 3: control unit, 33: pressing rotor

Claims

1. an image forming means for forming an image on a recording material; a conveying path for conveying the recording material toward the image forming means; A first light emitting means for emitting light of a first wavelength; A second light emitting means for emitting light having a second wavelength different from the first wavelength; a light receiving means for receiving the light of the first wavelength emitted by the first light emitting means and the light of the second wavelength emitted by the second light emitting means, on an opposite side of the transport path to the first light emitting means and the second light emitting means; a control means for controlling image forming conditions when forming an image on the recording material based on the amount of light of the first wavelength received by the light receiving means and the amount of light of the second wavelength received by the recording material; a first rotating body that presses the recording material conveyed through the conveying path; a second rotating body that is disposed at a position different from the first rotating body in a direction of a rotation axis of the first rotating body and presses the recording material conveyed through the conveying path; Equipped with An image forming apparatus characterized in that, when viewed in the direction of the rotation axis, the optical path of light connecting the first light-emitting means and the light-receiving means, and the optical path of light connecting the second light-emitting means and the light-receiving means overlap with the first rotating body and the second rotating body, and the first light-emitting means and the second light-emitting means are disposed between the first rotating body and the second rotating body in a direction perpendicular to the transport direction of the recording material.

2. 2. The image forming apparatus according to claim 1, wherein the first rotating body and the second rotating body are configured to rotate in accordance with the conveyance of the recording material.

3. The image forming apparatus according to claim 2, characterized in that the control means detects a value related to the amount of moisture contained in the recording material based on the amount of light of the first wavelength that has passed through the recording material and the amount of light of the second wavelength that has passed through the recording material received by the light receiving means while the first rotating body and the second rotating body are rotating in response to the transport of the recording material.

4. Further, another light emitting means is provided on the same side as the light receiving means with respect to the transport path, a rotating body including the first rotating body, the second rotating body, and a connecting member connecting the first rotating body and the second rotating body, the rotating body having a first region that transmits light and a second region that transmits weaker light than the first region, the light receiving means further receives light emitted by the other light emitting means and reflected by the recording material; the control means further detects the surface property of the recording material based on the light emitted by the separate light emitting means and reflected by the recording material, the light receiving means receiving the light, An image forming apparatus according to any one of claims 1 to 3, characterized in that the second area is located opposite an area of ​​the light receiving means that receives light emitted by the other light emitting means and reflected by the recording material, via the recording material.

5. 5. The image forming apparatus according to claim 4, wherein the second area is an area made of a black member.

6. A connecting member is provided to connect the first rotating body and the second rotating body, An image forming apparatus according to any one of claims 1 to 5, characterized in that, when viewed in the direction of the rotation axis, the optical path of light connecting the first light-emitting means and the light-receiving means, and the optical path of light connecting the second light-emitting means and the light-receiving means do not overlap with the connecting member.

7. 7. The image forming apparatus according to claim 6, wherein the area of ​​the cross section of the connecting member perpendicular to the rotation axis is smaller than the areas of the cross sections of the first rotating body and the second rotating body perpendicular to the rotation axis.

8. 8. The image forming apparatus according to claim 1, wherein the light receiving section includes a plurality of light receiving elements arranged along a direction perpendicular to a conveying direction of the recording material.

9. the image forming unit includes a transfer unit that transfers an image onto the recording material, 2. The image forming apparatus according to claim 1, wherein the control means controls a transfer voltage or a transfer current when the transfer means transfers the image onto the recording material.

10. the image forming unit includes a fixing unit for fixing the image on the recording material, 2. The image forming apparatus according to claim 1, wherein the control means controls a fixing temperature when the fixing means fixes the image on the recording material.

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