JP7625646B2 - Image forming device - Google Patents

Description

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

Electrophotographic image forming devices such as copiers and laser printers transfer a toner image formed on an image carrier to a recording material, and heat and press the recording material to which the toner image has been transferred to fix the toner image to the recording material. Transfer conditions such as transfer bias, and fixing conditions such as the fixing temperature during fixing and the 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 when 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 device 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 device. 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.

For this reason, Patent Documents 1 to 3 disclose configurations for detecting the amount of moisture contained in individual recording materials. Patent Documents 1 to 3 disclose configurations for irradiating a detection target for moisture with light in the wavelength range absorbed by water and light in the wavelength range not absorbed by water, and detecting the moisture amount of the detection target based on the amount of reflected light, etc.

JP 2013-57513 A Japanese Patent Application Publication No. 9-210902 Japanese Patent Application Publication No. 9-61351

The recording material being transported in the image forming device may fluctuate in a direction perpendicular to the image forming surface, i.e., flutter. If light is irradiated onto the recording material being transported while fluttering, the value relating to the amount of moisture contained in the recording material cannot be detected accurately due to the fluctuation of the image forming surface caused by the flutter.

The present invention provides an image forming device that accurately detects the value related to the amount of moisture contained in the recording material and controls the image formation conditions.

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 transport path for transporting the recording material toward the image forming unit, a first light emitting unit that emits light of a first wavelength, a second light emitting unit that emits light of a second wavelength different from the first wavelength, a light receiving unit that receives the light of the first wavelength emitted by the first light emitting unit and the light of the second wavelength emitted by the second light emitting unit on the opposite side of the transport path to the first light emitting unit and the second light emitting unit, and forms an image on the recording material based on the amount of light of the first wavelength received by the light receiving unit and the amount of light of the second wavelength received by the recording material. the recording material conveyed along the conveying path; a first rotating body pressing the recording material conveyed along the conveying path; and a second rotating body arranged at a position different from the first rotating body in the direction of the rotation axis of the first rotating body and pressing the recording material conveyed along the conveying path, wherein when viewed in the direction of the rotation axis, an optical path of light connecting the first 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 overlap with the first rotating body and the second rotating body, and the first light-emitting means and the second light-emitting means are arranged between the first rotating body and the second rotating body in a direction perpendicular to the conveying direction of the recording material .

According to the present invention, it is possible to accurately detect the value related to the amount of moisture contained in the recording material and control the image formation conditions.

FIG. 1 is a diagram illustrating the configuration of an image forming apparatus according to an embodiment. 1 is a perspective view of a moisture sensing device according to one embodiment. FIG. 1 is a diagram showing the configuration of a moisture detection device according to an embodiment. FIG. 1 is a diagram showing the configuration of a moisture detection device according to an embodiment. FIG. 2 is a diagram illustrating the positional relationship of each component of the moisture detection device according to the embodiment. 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment. 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment. FIG. 11 is a diagram showing determination information according to an embodiment. 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment. 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment. FIG. 1 is a diagram showing the configuration of a moisture detection device according to an embodiment. FIG. 1 is a diagram showing the configuration of a moisture detection device according to an embodiment. 5A to 5C are diagrams illustrating the operation of the moisture detection device according to the embodiment.

Below, 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. Also, in each of the following figures, components that are not necessary for explaining the embodiments are omitted from the figures.

First Embodiment
FIG. 1 is a configuration diagram of an image forming apparatus 1 according to the present 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 adheres 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.

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 the position opposite the secondary transfer roller 19. Meanwhile, the recording material P stored in the cassette 2 is transported to the position opposite the secondary transfer roller 19 by the feed roller 4, the 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 opposite 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 the blade 35 of the cleaning device 36. The recording material P to which the toner image has been transferred is transported to the fixing unit 21. The fixing unit 21 heats and pressurizes 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 shown 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 opposite the secondary transfer roller 19, where an image is formed on the other side.

The image forming apparatus 1 also includes a moisture detection device 30 that detects values 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 transport path along which the recording material P is transported from the light-emitting section 31. 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 pressure rotor (not shown in FIG. 1) to ensure stable transport of the recording material.

The control unit 3 of the image forming device 1 is the control unit for the entire image forming device, 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 device 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.

Figure 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 through the moisture detection device 30, and a value related to the moisture content is detected during the transport process. As shown in Figure 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 held between the pressing rotor 33, and is configured to rotate due to the transport of the recording material P. As a result, the recording material P is prevented from fluttering within the moisture detection device 30 and is transported in a stable state.

Figure 3 is a view of the moisture detection device 30 from the upstream side in the conveying direction of the recording material P. The light emitting unit 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 unit 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 that it can receive the 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 electrical signal according to the amount of light received. Each light receiving element included in the line light receiving element LS can be an inexpensive element that has a light receiving sensitivity in the visible light and near infrared light range (approximately 400 to 1000 nm) that includes the emission wavelengths of the light emitting elements L1 and L2. 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 avoiding scratching the glass surface, it is possible to prevent a decrease in the accuracy of moisture detection, which will be described later.

FIG. 4 is a cross-sectional view taken along line A-A in FIG. 3, and FIG. 5 is an explanatory diagram of the arrangement 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 _a-b between the imaginary line La and the central axis of rotation Lb and the distance L _b-c between the central axis of rotation Lb and the straight line Lc are approximately equal.

Figures 6 and 7 show the state in which the light-emitting elements L1 and L2 are emitting light. Note that Figures 6 and 7 are views 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 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 amount of light L1L received and the amount of light L2L received can be determined, respectively.

When the light L1L and L2L pass through the transparent pressing rotor 33, they are attenuated by internal reflection and loss. 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, which has 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 light received while holding the recording material P. Therefore, the influence of localized 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.

Hereinafter, 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 L2L having a first wavelength of 560 nm and a second wavelength of 850 nm different from the first wavelength. First, it is assumed that the light emission intensity of the light emitting element L1 is equal to that of the light emitting element L2. The amount of light emitted by the light emitting element L1 and transmitted through the recording material P is called 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 called 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 according to the moisture content of the recording material P, as shown in FIG. 8. Note that FIG. 8 shows the measurement results of the moisture content and the transmitted light amount difference when plain paper (60g paper) having a basis weight of 60 g/ ^m2 is used as the recording material P. Note that 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.

The reason why the difference in the amount of transmitted light changes depending on the moisture content of the recording material P will be explained 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 change in the amount of transmitted light due to the change in surface properties is not very wavelength-dependent, so the amount of change 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 absorption of light due to the moisture contained in the recording material P is wavelength-dependent, so the longer the wavelength, the greater the amount of absorption. Therefore, the amount of change in the amount of transmitted light due to the light absorption associated with the change in the moisture content of the recording material P varies depending on the wavelength, and the difference in the amount of transmitted light changes. Therefore, the change 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.

In this embodiment, the relationship between the moisture content and the difference in the amount of transmitted light as shown in FIG. 8 is measured in advance, and judgment information indicating the relationship between the moisture content and the difference in the amount of transmitted light is stored in the control unit 3. Then, the control unit 3 uses the judgment 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. It is also possible to configure the judgment information to be obtained for each basis weight of the recording material used in image formation. In this case, the image forming device 1 determines the moisture content of the recording material based on the judgment information corresponding to the basis weight of the recording material to be image formed. Next, a method for obtaining 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 obtained 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 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 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 the emission intensity between the light emitting element L1 and the light emitting element L2.

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 the 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 the value related to the moisture content of the recording material can be detected with high accuracy. Note that instead of making the entire pressing rotor 33 out of transparent materials, it is also possible to make only the areas through which the lights L1L and L2L pass out of transparent materials. Also, in this embodiment, it is possible to detect the value related to the moisture content of the recording material without using an expensive light receiving element that has 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 the transfer voltage (transfer bias) and transfer current when transferring an image to the 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 the fixing temperature and the conveyance 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.

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, the position 38 of the rotation center of the pressing rotor 34 in the recording material transport direction is shifted a predetermined distance from the position 37 in the first embodiment to the upstream side in the recording material transport direction.

Therefore, the light L1L and L2L received by the line light receiving element LS is not the 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 with reduced attenuation by the pressing rotor 34. Because 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.

The amount of shift of the rotation center upstream 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 where 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 downstream in the recording material transport direction.

As described above, the connecting member 343 including the rotation axis of the pressing rotor 34 is positioned so as not to 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.

Third Embodiment
Next, the third embodiment will be described with a focus on differences from the first embodiment. FIGS. 11 and 12 are diagrams of the moisture detection device according to this embodiment. FIG. 11 is a diagram seen from the upstream side in the conveying direction of the recording material P, and FIG. 12 is a cross-sectional view taken along the line A-A in FIG. 11. 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 FIG. 11, in this embodiment, the 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 FIG. 11, the light-emitting elements L1 and L2 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.

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, for example, in JP 2014-114131 A. Simply put, 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 advance in the image forming device, 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 emitted by the light emitting element L3.

Figure 13 shows the state in which the light-emitting elements L1, L2, and L3 are illuminated, and corresponds to Figure 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 rotor 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 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 bottom in the figure through the light guide LG. The light-receiving element in an area of the line light-receiving element LS that is 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 rotor 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 of the light emitted by the light emitting element L3 across the recording material P. 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 from the recording material P emitted by the light emitting elements L1 and L2 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.

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 device with a separate function for determining the surface properties of the recording material, and allowing the image forming layer to be made smaller.

[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.

31: Light emitting unit, 32: Light receiving unit, 3: Control unit, 33: Pressurized rotating body

Claims (10)

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 unit that controls image forming conditions when forming an image on the recording material based on the amount of light of the first wavelength that is received by the light receiving unit and transmitted through the recording material and the amount of light of the second wavelength that is received by the light receiving unit and transmitted through 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. 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. 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. 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. The image forming device according to claim 4, characterized in that the second area is an area made of a black material. 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. 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. The image forming apparatus according to any one of claims 1 to 7, characterized in that the light receiving means includes a plurality of light receiving elements arranged along a direction perpendicular to the conveying direction of the recording material. 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. 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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