JP6479144B2 - Image forming apparatus, recording material discrimination sensor - Google Patents

Description

The present invention relates to an image forming apparatus and a recording material discrimination sensor .

Image forming apparatuses such as copying machines and laser printers include a latent image carrier that carries a latent image, a developing device, a transfer device, and a fixing device. The developing device visualizes the latent image as a developer image by applying the developer to the latent image carrier. The transfer device transfers the developer image by the developing device to a recording material conveyed in a predetermined direction under a predetermined transfer condition. The fixing device fixes the developer image on the recording material by heating and pressurizing the recording material on which the developer image has been transferred by the transfer device under predetermined fixing conditions.
Conventionally, in such an image forming apparatus, for example, a user operates an operation panel or the like provided in the main body of the image forming apparatus, so that the size and type of recording paper that is a recording material (hereinafter also referred to as paper type). Can be set. The transfer conditions (for example, transfer bias and recording paper transport speed during transfer) and fixing conditions (for example, the fixing temperature and recording paper transport speed during fixing) are controlled according to the setting. Yes.
In recent years, a method has been proposed in which the type of recording material is discriminated using a sensor for discriminating the recording material inside the image forming apparatus, and control is performed so that transfer conditions or fixing conditions are set according to the discrimination results. . Specifically, Japanese Patent Application Laid-Open No. H10-260260 discloses a device that determines a thickness by providing a light source at a position facing a sensor that determines a recording material, and detecting transmitted light that has passed through the recording material.
Further, Patent Document 2 discloses a configuration in which when the recording material is greatly curled, the paper followability is improved and the paper thickness detection accuracy is increased.

JP 2001-139189 A JP 2007-277011 A

Here, in the configuration disclosed in Patent Document 2, in order to carry out with sufficient accuracy, a sensor that detects the thickness from the lever rotation center by reducing the distance from the rotation center of the lever to the contact portion with the recording material. It is necessary to arrange the distance to far. Therefore, a space for arranging each member for detecting the recording material is increased.
Further, the configuration of a conventional example for detecting the characteristics of the recording material will be described with reference to FIGS. As shown in FIGS. 6 and 7, the first contact member 25 and the second contact member 21 are arranged in the apparatus main body so as to sandwich the recording material being conveyed. The second abutting member 21 is provided with a reflection light emitting part 62 and a light receiving element 63, and the light receiving element 63 receives light emitted from the reflection light emitting part 62 and reflected by the recording material. Based on the amount of light received at this time, transfer conditions and fixing conditions are set.
Here, as shown in FIG. 6, in the configuration in which the recording material is caused to follow by the rotational movement of the lever and receives the reflected light of the recording material, the optical axis is perpendicular to the transport direction in the absence of the recording material, so The reflected light returns to the light receiving element 63. However, as shown in FIG. 7, when the recording material 90 is being conveyed and the position of the recording material 90 is biased to one side, such as the first contact member 25 side, the recording material 90 is rotated by rotating the lever. In contrast, the optical axis is inclined. In that case, the reflected light from the recording material 90 may not return to the light receiving element 63 as intended. Therefore, the detection accuracy of the characteristics of the recording material 90 is lowered.

  In view of the above problems, an object of the present invention is to detect characteristics of a recording material with high accuracy in a small space.

In order to achieve the above object, an image forming apparatus according to the present invention includes:
A light-emitting unit that emits light to the recording material, and a light-receiving unit that receives the light emitted from the light-emitting unit and that passes through the recording material,
An image forming apparatus comprising: a control unit that changes an image forming condition when forming an image on the recording material based on a detection result of the detection unit;
The detection means is provided so as to face each other so that the recording material can be sandwiched between the first contact member that contacts one surface of the recording material and the second contact member that contacts the other surface. A first urging member for urging the first abutting member against the second abutting member; and a first urging member for urging the second abutting member against the first abutting member. 2 biasing members,
The first abutting member is centered on a position where the urging forces of the first urging member and the second urging member are balanced and the first abutting member and the second abutting member are stopped. direction and away from the direction of approach to the second abutment member, said second abutment member Ri each movable der toward and away from a direction of approaching to the first contact member, the first contact member And a guide portion for guiding the first contact member and the second contact member so as to be movable in a direction perpendicular to the surface of the recording material sandwiched by the second contact member. Have
A position where the first urging member is attached to the first abutting member when viewed from the direction of the rotation axis of the conveying roller that conveys the recording material between the first abutting member and the second abutting member. The light emitting part or the light receiving part is arranged on an imaginary line connecting the position where the second urging member is attached to the second contact member .
In order to achieve the above object, the recording material discrimination sensor according to the present invention is
Including a light emitting unit for irradiating light to the recording material and a light receiving unit for receiving light emitted from the light emitting unit through the recording material, and having a detecting means for detecting characteristics of the recording material,
In the recording material discrimination sensor for discriminating the type of the recording material based on the detection result of the detection means,
The detection means includes a first abutting member that abuts on one surface of the recording material and a second abutting member that abuts on the other surface, which are provided opposite to each other and can sandwich the recording material. A first urging member for urging the first abutting member against the second abutting member; and a second urging the second abutting member against the first abutting member. A biasing member,
The first abutting member is centered on a position where the urging forces of the first urging member and the second urging member are balanced and the first abutting member and the second abutting member are stopped. direction and away from the direction of approach to the second abutment member, said second abutment member Ri each movable der toward and away from a direction of approaching to the first contact member, the first contact member And a guide portion for guiding the first contact member and the second contact member so as to be movable in a direction perpendicular to the surface of the recording material sandwiched by the second contact member. Have
A position where the first urging member is attached to the first abutting member when viewed from the direction of the rotation axis of the conveying roller that conveys the recording material between the first abutting member and the second abutting member. The light emitting part or the light receiving part is arranged on an imaginary line connecting the position where the second urging member is attached to the second contact member .

  According to the present invention, it is possible to accurately detect the characteristics of a recording material in a space-saving manner.

FIG. 3 is a schematic cross-sectional view showing a state in which the recording material passes in Example 1 Schematic cross-sectional view showing a state in which the recording material does not pass in Example 1 The perspective view which shows an example of the contact member of Example 2. Schematic sectional view showing the configuration of the image forming apparatus according to the present embodiment Schematic diagram for explaining detection of recording material characteristics Schematic sectional view showing a state in which the recording material does not pass in the conventional example Schematic sectional view showing a state in which the recording material passes in the conventional example Sectional drawing of the contact member of Example 2 It is sectional drawing of the contact member of Example 2, Comprising: The figure seen from the contact surface side Schematic sectional view of recording material detection means of embodiment 3 Schematic sectional view of recording material detection means of embodiment 4

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

<Configuration of image forming apparatus>
First, an outline of the configuration of an image forming apparatus according to the present embodiment that forms an image on a recording material conveyed in the apparatus main body will be described with reference to FIG. FIG. 4 is a schematic cross-sectional view illustrating the configuration of the image forming apparatus according to the present embodiment. As shown in FIG. 4, the image forming apparatus according to the present exemplary embodiment attaches and detaches process cartridges 2Y, 2M, 2C, and 2K that contain toner as developers of the respective colors of yellow Y, magenta M, cyan C, and black K. Be prepared for possible. In the following description, the subscripts Y, M, C, and K given to the reference numerals are omitted when there is no particular distinction.

  The process cartridges 2Y, 2M, 2C, and 2K include photosensitive drums 1Y, 1M, 1C, and 1K as image carriers. The photosensitive drums 1Y, 1M, 1C, and 1K are rotatably supported at both ends, and a driving force is transmitted from one end by a drive motor and a drive transmission unit (not shown). Rotate in the direction.

  Further, the process cartridges 2Y, 2M, 2C, and 2K include charging rollers 3Y, 3M, 3C, and 3K, and developing rollers 4Y, 4M, 4C, and 4K as developer carriers. The surface of each photoconductive drum 1Y, 1M, 1C, and 1K coated with an organic photoconductive layer is uniformly charged by applying a charging bias to the charging rollers 3Y, 3M, 3C, and 3K. The

  The image forming apparatus according to the present embodiment includes a laser scanner unit 5 as an exposure unit, an intermediate transfer belt 6, a driving roller 7, a driven roller 8, and primary transfer rollers 9Y, 9M, 9C, and 9K. Further, a paper feed cassette 10, a secondary transfer roller 15, a fixing roller pair 16, a discharge roller pair 17, and a discharge tray 18 are provided.

  The laser scanner unit 5 forms an electrostatic latent image by selectively exposing the surface of the photosensitive drum 1 charged by the charging roller 3 with laser light. Then, the developing roller 4 develops the electrostatic latent image by supplying toner to the surface of the photosensitive drum 1, and forms a toner image as a developer image on the surface of the photosensitive drum 1.

  The intermediate transfer belt 6 is stretched by a driving roller 7 and a driven roller 8. Then, the intermediate transfer belt 6 is in contact with the photosensitive drum 1 by the urging of the primary transfer roller 9, and the drive roller 7 is rotated by a drive motor and drive transmission means (not shown), whereby the intermediate transfer belt 6 is rotated in the direction indicated by the arrow B in FIG. It is driven to rotate clockwise.

  A predetermined transfer bias is applied to the primary transfer rollers 9Y, 9M, 9C, and 9K, and the color toner images on the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K are sequentially superimposed on the intermediate transfer belt 6. Transferred (primary transfer) to form a four-color toner image.

  A recording material 90 such as paper is stacked on the paper feed cassette 10, and the recording material 90 is fed by a feed roller 12 driven at a predetermined timing by a drive motor and a drive transmission unit (not shown). Thereafter, the sheet passes through the conveying roller pair 13 and the registration roller pair 14 and is conveyed to a secondary transfer position that is a contact portion between the intermediate transfer belt 6 and the secondary transfer roller 15. At the secondary transfer position, the four color toner images on the intermediate transfer belt 6 are transferred to the recording material 90 by the secondary transfer roller 15 to which a predetermined bias is applied.

  The recording material 90 to which the toner images of four colors are transferred is conveyed to the fixing roller pair 16 and the toner image is melted and fixed on the recording material 90 by heat and pressure, whereby a color image is obtained. Further, the recording material 90 conveyed by the fixing roller pair 16 passes through the discharge roller pair 17 and is discharged and stacked on the discharge tray 18.

<Measuring means for recording material characteristics>
Next, detection of the characteristics of the recording material 90 will be described with reference to FIG. FIG. 5 is a schematic diagram for explaining a recording material characteristic detection unit. Here, the characteristics of the recording material are the size, thickness, surface property and the like of the recording material. By detecting the characteristics of the recording material, the type of the recording material can be specified.

As shown in FIG. 5, the recording material detection means 20 as a detection means for detecting the characteristics of the recording material 90 includes a diffusion member 22 as a diffusion part, a transmission light emitting part 23 as a light emitting part, a lens 61, and a light emitting part. The light emitting unit 62 for reflection and a light receiving element 63 as a light receiving unit are included. Of the functions of the recording material detection means 20, the detection of the characteristics of the recording material 90 based on the light reception result of the light receiving element 63 is performed by sending the light reception result to a controller (not shown). That is, a part of the configuration of the recording material detection unit 20 is a part of the controller. In addition, Example 1 below
In the above description, the configuration in which the transmissive light emitting unit 23 is provided has been described. However, it is sufficient that at least one of the transmissive light emitting unit 23 and the reflective light emitting unit 62 is provided as the light emitting unit.

  The light emitted from the transmission light emitting unit 23 is diffused by the diffusion member 22. Then, the diffused light passes through the recording material 90 and further passes through the lens 61. The thickness of the recording material 90 is detected by detecting the amount of light that has passed through the lens 61 in the light receiving element 63.

  Further, the light emitted from the reflection light emitting unit 62 is reflected by the recording material 90, and the light passes through the lens 61. Then, the surface property of the recording material 90 is detected by detecting the amount of light that has passed through the lens 61 by the light receiving element 63.

  The value of the amount of light that has received the transmitted light and the amount of light that has received the reflected light are sent to the controller, and the controller detects that the paper is thin if the amount of transmitted light is large, and is thick if it is small. If the amount of reflected light is large, it is detected as smooth paper, and if the amount of reflected light is small, it is detected as paper with a rough surface. Based on the detection result, the bias of the secondary transfer roller 15, the heating temperature of the fixing roller pair 16, and the process speed can be changed to predetermined conditions.

Example 1
Next, a characteristic configuration of the first embodiment will be described with reference to FIGS. 1, 2, and 4. FIG. 1 is a schematic cross-sectional view showing a state in which the recording material passes through the recording material detection means. FIG. 2 is an enlarged schematic cross-sectional view showing a state in which the recording material does not pass through the recording material detection means. As shown in FIG. 4, in the first exemplary embodiment, recording that detects the characteristics of the recording material 90 between the conveying roller pair 13 and the registration roller pair 14 that is located downstream of the conveying roller pair 13 in the conveying direction. Material detection means 20 is arranged. In addition, a conveyance path between the conveyance roller pair 13 and the registration roller pair 14 located downstream of the conveyance roller pair 13 in the recording material conveyance direction is formed by an inner guide 51 and an outer guide 52.

  Here, in the image forming apparatus according to the first embodiment, the curved portion of the conveyance path formed by the inner guide 51 and the outer guide 52 contacts the surface (first surface) of the recording material 90 on the inner guide 51 side. It has the 1st contact member 25 which touches. And it has the 2nd contact member 21 contacted with the back surface (2nd surface) of the recording material 90 in the outer guide 52 side provided facing the 1st contact member 25. As shown in FIG.

  The transmission light emitting portion 23 of the recording material detection means 20 is attached to the first contact member 25 on the inner guide 51 side, and the light receiving element 63 of the recording material detection means 20 that receives the light is on the outer guide 52 side. The second contact member 21 is attached.

  Further, the first contact member 25 is provided to be urged against the second contact member 21 by a spring 26 as a first urging member. The second abutting member 21 is held by a holding member 21a, and is urged against the first abutting member via the holding member 21a by a spring 27 as a second urging member. . When the recording material 90 is transported in the transport path, the recording material 90 is sandwiched between the first contact member 21 and the second contact member.

  Here, as shown in FIG. 2, the inner guide 51 has a recording material 90 in which the moving direction (moving direction) of the first contact member 25 is sandwiched between the first contact member 25 and the second contact member 21. It has a guide surface 55 as a guide part for guiding in a direction perpendicular to the direction. Similarly, the outer guide 52 guides the movable direction (moving direction) of the second contact member 21 in a direction perpendicular to the recording material 90 sandwiched between the first contact member 25 and the second contact member 21. It has a guide surface 56 as a guide part.

  In the first embodiment, the weight and dimensional tolerances of the components are set so that the biasing force of the spring 27 that biases the second abutting member 21 is stronger than the biasing force of the spring 26 that biases the first abutting member 25. The spring pressure of the spring 26 and the spring 27 was set in consideration of variation.

  As shown in FIG. 2, when the recording material 90 is not in a position sandwiched between the first contact member 25 and the second contact member 21, the position of the second contact member 21 including the light receiving element 63 is the holding member. It is determined by the stopper portion 24 as a restricting portion provided in 21 a coming into contact with the outer guide 52. The stopper portion 24 is provided on each of the upstream side and the downstream side in the conveyance direction of the recording material 90, and has a shape protruding from the outer guide 52 side to the inner guide 51 side. The stopper portion 24 always comes into contact with the outer guide 52 when the recording material 90 is not in a position where it is sandwiched between the first contact member 25 and the second contact member 21.

  Further, when the recording material 90 is transported, the upstream side in the transport direction of the second contact member 21 is a tapered surface 54 so that the recording material 90 is not caught by the second contact member 21 and the upstream side thereof. The side end portion is configured to be outside the outer guide surface 53 of the outer guide 52.

  In the first embodiment, the first contact member 25 is formed of a material such as white POM (polyacetanol) and has a function of uniformly diffusing the light emitted from the light-emitting portion 23 for transmission (FIG. 5). The function of the diffusion member 22 described with reference to FIG. Therefore, the light receiving element 63 provided on the second contact member 21 receives the light uniformly diffused by the first contact member 25 through the recording material 90.

  Here, the timing of detecting the characteristics of the recording material 90 in the first embodiment will be described. When the recording material 90 is conveyed, first, the recording material 90 is conveyed along the outer guide 52 by the conveying roller pair 13. At this time, as shown in FIG. 1, the holding member 21 a is pushed into the outer guide 52 side by the recording material 90 via the second contact member 21, and the stopper portion 24 is separated from the outer guide 52. At the same time, the first contact member 25 follows the recording material 90 and moves to the outer guide 52 side, thereby maintaining the state where the recording material 90 is sandwiched.

  Thereafter, when the leading edge of the recording material 90 reaches the registration roller pair 14, the recording material 90 is conveyed by the registration roller pair 14 and the conveyance roller pair 13. The conveyance speed by the registration roller pair 14 is set to be faster than the conveyance speed by the conveyance roller pair 13, and the recording material 90 gradually approaches the inner guide 51 side. In the first exemplary embodiment, the detection timing of the characteristics of the recording material 90 starts before the leading edge of the recording material 90 reaches the registration roller pair 14 and until the leading edge of the recording material 90 reaches the secondary transfer roller 15. In addition, the stopper portion 24 is not in contact with the outer guide 52.

  As described above, in the image forming apparatus according to the first embodiment, the movable direction of the first contact member 25 including the transmission light emitting unit 23 and the second contact member including the light receiving element 63 is set with respect to the recording material 90. It has the guide surface 55 and the guide surface 56 which guide so that it may become a perpendicular direction. With such a configuration, the distance between the light receiving element 63 and the recording material 90, and the transmission light emitting portion 23 and the recording material 90 is kept constant even when the recording material detection means 20 is disposed in the vicinity of the curved conveyance path. The detection accuracy can be kept good. In particular, this configuration is effective when it is difficult to arrange the recording material detection unit 20 in a linear conveyance path such as a small image forming apparatus.

In the first embodiment, the transmission light-emitting portion 23 is provided on the first contact member 25 as one of the first contact member 25 and the second contact member 21, and the other second contact is performed. Although the light receiving element 63 is provided on the member 21, the reverse structure may be used. In the first embodiment, the urging force is generated using the spring-like springs 26 and 27. However, the recording material 90 may be clamped only by the weight of the component without using the spring, or the tension spring. The biasing force may be given by other means.

  In the first embodiment, the recording material detecting unit 20 detects the surface roughness of the recording material by adopting a configuration having a light emitting unit and a light receiving unit. However, the recording material detecting unit 20 detects the movement amount and pressure of the light receiving unit and the light emitting unit. In this case, the thickness of the recording material may be detected. Further, it may be a color sensor that detects the density and chromaticity of the patch array on the recording material.

(Example 2)
Hereinafter, Example 2 will be described with reference to FIGS. FIG. 8 is a cross-sectional view of the first contact member according to the second embodiment. FIG. 9 is a cross-sectional view of the first abutting member of Example 2 as seen from the contact surface side with the recording material (see FIG. 8 from the left side). Note that the schematic configuration of the image forming apparatus is the same as that of the first embodiment, and a description thereof will be omitted. The second embodiment is characterized in that the recording material detection unit 28, which is a portion through which light emitted from the transmissive light emitting unit 23 passes, does not contact the recording material 90.

  In the first embodiment, the recording material contact surface that contacts the recording material 90 of the first abutting member 25 has a flat configuration. On the other hand, in Example 2, the recording material contact portion (contact surface) 29 of the first contact member 25 is provided with a recess (non-contact surface), and the characteristics of the recording material 90 are obtained using light passing through the recess. It was set as the structure which detects. In the second embodiment, this convex portion is used as the recording material detection unit 28.

  When the recording material detection unit is configured to be non-contact with the recording material 90, the recording material 90 flutters and the detection accuracy is lowered. However, the recording material detection accuracy similar to that of the first embodiment can be obtained by sufficiently reducing the area of the recording material detection unit 28 and making the recording material detection unit 28 and the recording material contact unit 29 close to each other as in the present example. Become. That is, even if the recording material detection unit 28 and the recording material contact unit 29 are not necessarily matched, the distance from the recording material 90 can be kept constant, and the characteristics of the recording material 90 can be detected with high accuracy.

  With such a configuration, the detection point itself of the recording material contact portion 29 does not come into strong contact with the recording material 90, so that the recording material detection portion 28 can be prevented from being extremely scraped or scratched by the recording material 90. . Furthermore, it is also effective in a configuration in which the characteristics of the recording material 90 are detected in a non-contact manner using ultrasonic waves.

  As described above, in the second embodiment, the recording material detection unit 28 can detect the characteristics of the recording material 90 in a non-contact manner, and scratches and the like when the recording material 90 passes the recording material detection unit 28 can be detected. Even in case of concern, the followability to the recording material 90 is good, and the discrimination accuracy of the recording material 90 is improved.

  Note that the shapes of the recording material contact surface and the recording material detector are not limited to the configurations shown in FIGS. 8 and 9, the recording material detection unit 28 of the first contact member 25 has a concave shape. For example, the first contact member 25 as shown in FIG. 29 may be provided, and the recording material detector 28 may have a flat configuration. Even in the configuration as shown in FIG. 3, by bringing the recording material contact surface and the recording material detection unit close to each other, an effect equivalent to the configuration in which the recording material contact surface and the recording material detection unit are at the same point can be obtained.

(Example 3)
Next, Example 3 will be described with reference to FIG. FIG. 10 is a schematic cross-sectional view of the recording material detection unit of Example 3 and shows a state in which the recording material does not pass. Note that the schematic configuration of the image forming apparatus is the same as that of the first embodiment, and a description thereof will be omitted.

In the configuration of the third embodiment, when the recording material 90 is not located between the first contact member 25 and the second contact member 21, the first contact member 25 and the second contact member 21 are connected to the inner guide. 51 and the outer guide 52 are in a state where the mutual forces are balanced. That is, the urging force of the spring 26 that urges the first contact member 25 and the urging force of the spring 27 that urges the first contact member have the same magnitude. Therefore, unlike the configuration of the first embodiment in which the urging force of the spring 26 and the urging force of the spring 27 are different, the third embodiment has a configuration that does not have the stopper portion 24.

  By doing so, the force relationship between each other can be weakened, and even thin paper with weak rigidity is difficult to jam. For example, when the stopper portion 24 is provided on either the first contact member 25 side or the second contact member 21 side, the side on which the stopper portion 24 is provided is 50 ± 10 gf, and the opposite side is 30 ± 5 gf. It is necessary to set so that the stopper 24 side always becomes strong even if the parts vary. However, if they are balanced, both can be 30 ± 5 gf.

  Moreover, in the structure of Example 3, the 1st contact member 25 and the 2nd contact member 21 can move to a biasing direction and a counter-biasing direction. Therefore, even when it is not clear whether the recording material 90 is conveyed along the inner guide 51 or the outer guide 52 when the recording material 90 is conveyed, the recording material 90 can be followed, which is effective.

  However, it is necessary to provide the tapered surface 57 at the end of the first abutting member 25 on the upstream side in the transport direction so as to be inside the inner guide surface 58. Further, the end of the tapered surface 54 of the second contact member 21 on the upstream side in the conveyance direction needs to be provided outside the outer guide surface 53. Furthermore, it is necessary to provide a taper shape larger than the configuration of the first embodiment in which the stopper portion 24 is provided. The reason why such a configuration is necessary is that when the recording material 90 is conveyed, the recording material 90 is jammed by the end of the second contact member 21 or the end of the first contact member 25. This is to prevent it.

  As described above, in the third embodiment, since the pressures of the first contact member 25 and the second contact member 21 can be set low, it is possible to convey thin paper or the like that is less rigid than the first embodiment. It becomes possible.

Example 4
Next, Example 4 will be described with reference to FIG. FIG. 11 is a schematic cross-sectional view of the recording material detection unit of Example 4 and shows a state where the recording material has not passed. Note that the schematic configuration of the image forming apparatus is the same as that of the first embodiment, and a description thereof will be omitted.

  In the fourth embodiment, as in the first embodiment, a recording material detection unit 20 that detects characteristics of the recording material 90 is disposed between the conveyance roller pair 13 and the registration roller pair 14. The recording material detection unit 20 according to the fourth embodiment includes a measurement circuit 70, an arithmetic circuit 80, and a control circuit 100. In the fourth embodiment, a conductive electrode 31 as a first contact member and a conductive electrode 32 as a second contact member are provided. The electrode 32 is grounded to GND, and the electrode 31 is electrically connected to the measurement circuit 70.

  The electrode 31 and the electrode 32 are disposed at positions facing each other, and are provided so as to sandwich the recording material 90 being conveyed. As in the first embodiment, the movement direction of the electrode 31 and the electrode 32 is perpendicular to the recording material 90 by the guide surface 55 and the guide surface 56 of the conveyance path formed by the inner guide 51 and the outer guide 52. Guided by Therefore, even when the recording material detection means 20 is disposed in the vicinity of the curved conveyance path, the electrode 31 and the electrode 32 are not inclined with respect to the conveyed recording material 90, and the recording material 90 can be sandwiched. That is, the electrode 31 and the electrode 32 can maintain an appropriate contact state via the recording material 90.

The electrode 31 is urged against the electrode 32 by a spring 33 as a first urging member, and the electrode 32 is urged against the electrode 31 by a spring 34 as a second urging means. .

  The measurement circuit 70 is divided into a resistance measurement circuit 71 that measures the electrical resistance of the recording material 90 and a capacitance measurement circuit 72 that measures the capacitance of the recording material 90. The measurement circuit 70 measures and detects the electrical resistance or capacitance of the recording material 90 sandwiched between the electrode 31 and the electrode 32 by switching the switch circuit 35. The arithmetic circuit 80 is arithmetic means for performing arithmetic processing on the capacitance and the electric resistance value based on the detection result in the measurement circuit 70. Based on the calculation result of the calculation circuit 80, the control circuit 100 changes the bias of the secondary transfer roller 15, the heating temperature of the fixing roller pair 16 and the process speed to predetermined conditions.

  By adopting such a configuration, in the fourth embodiment, it is possible to reduce the size of the apparatus and improve the detection accuracy of the characteristics of the recording material.

  DESCRIPTION OF SYMBOLS 20 ... Recording material detection means, 25 ... 1st contact member, 21 ... 2nd contact member, 55, 56 ... Guide surface (guide part), 90 ... Recording material

Claims (13)

A light-emitting unit that emits light to the recording material, and a light-receiving unit that receives the light emitted from the light-emitting unit and that passes through the recording material,
An image forming apparatus comprising: a control unit that changes an image forming condition when forming an image on the recording material based on a detection result of the detection unit;
The detection means is provided so as to face each other so that the recording material can be sandwiched between the first contact member that contacts one surface of the recording material and the second contact member that contacts the other surface. A first urging member for urging the first abutting member against the second abutting member; and a first urging member for urging the second abutting member against the first abutting member. 2 biasing members,
The first abutting member is centered on a position where the urging forces of the first urging member and the second urging member are balanced and the first abutting member and the second abutting member are stopped. direction and away from the direction of approach to the second abutment member, said second abutment member Ri each movable der toward and away from a direction of approaching to the first contact member, the first contact member And a guide portion for guiding the first contact member and the second contact member so as to be movable in a direction perpendicular to the surface of the recording material sandwiched by the second contact member. Have
A position where the first urging member is attached to the first abutting member when viewed from the direction of the rotation axis of the conveying roller that conveys the recording material between the first abutting member and the second abutting member. The light emitting unit or the light receiving unit is disposed on an imaginary line connecting a position where the second urging member is attached to the second contact member . Said one of the first contact member and the second abutment member, said light emitting portion for emitting light to said recording material being sandwiched between the first contact member by the second contact member Have
The other of said first contact member and the second abutment member has a light receiving portion for receiving light transmitted through the recording material is irradiated from the light emitting portion,
The image forming apparatus according to claim 1, wherein the control unit changes the image forming condition based on a light reception result of the light receiving unit. One of the first contact member and the second abutment member includes a light emitting portion for emitting light to said recording material being held between the second abutment member and the first contact member has the light receiving portion for receiving the light reflected by the irradiated the recording material from the light emitting portion,
The image forming apparatus according to claim 1, wherein the control unit changes the image forming condition based on a light reception result of the light receiving unit. Wherein one of the first contact member and the second abutment member, said transmissive for emitting light to said recording material being held between the second abutment member and the first contact member Having a light emitting part,
The other of said first contact member and the second abutment member, the transmission and the light emitting portion for reflecting the irradiated light to the recording material, the recording material is irradiated from the light emitting unit for transparently a and said light receiving portion for receiving the light reflected by the irradiated said recording material from light and the light emitting portion for reflection was, the,
The image forming apparatus according to claim 1, wherein the control unit changes the image forming condition based on a light reception result of the light receiving unit. 3. The light emitting unit irradiates light onto a portion of the surface of the recording material sandwiched between the first contact member and the second contact member that is located on the virtual line. 5. The image forming apparatus according to any one of items 1 to 4.   6. The part of the first contact member or the second contact member through which light emitted from the light emitting unit passes does not contact the recording material. 6. 2. The image forming apparatus according to item 1. The image forming conditions include at least one of a transfer bias for transferring an image to the recording material, a fixing temperature for fixing the image transferred to the recording material, and a conveyance speed of the recording material. the image forming apparatus according to any one of claims 1 to 6, characterized in that. Including a light emitting unit for irradiating light to the recording material and a light receiving unit for receiving light emitted from the light emitting unit through the recording material, and having a detecting means for detecting characteristics of the recording material,
In the recording material discrimination sensor for discriminating the type of the recording material based on the detection result of the detection means,
The detection means is provided so as to face each other so that the recording material can be sandwiched between the first contact member that contacts one surface of the recording material and the second contact member that contacts the other surface. A first urging member for urging the first abutting member against the second abutting member; and a first urging member for urging the second abutting member against the first abutting member. 2 biasing members,
The first abutting member is centered on a position where the urging forces of the first urging member and the second urging member are balanced and the first abutting member and the second abutting member are stopped. direction and away from the direction of approach to the second abutment member, said second abutment member Ri each movable der toward and away from a direction of approaching to the first contact member, the first contact member And a guide portion for guiding the first contact member and the second contact member so as to be movable in a direction perpendicular to the surface of the recording material sandwiched by the second contact member. Have
A position where the first urging member is attached to the first abutting member when viewed from the direction of the rotation axis of the conveying roller that conveys the recording material between the first abutting member and the second abutting member. A recording material discrimination sensor , wherein the light emitting part or the light receiving part is arranged on an imaginary line connecting a position where the second urging member is attached to the second contact member . Said one of the first contact member and the second abutment member, said light emitting portion for emitting light to said recording material being sandwiched between the first contact member by the second contact member a, the other of the first contact member and the second abutment member has a light receiving portion for receiving light transmitted through the recording material is irradiated from the light emitting portion,
The recording material discrimination sensor according to claim 8 , wherein the type of the recording material is discriminated based on a light reception result at the light receiving unit. One of the first contact member and the second abutment member includes a light emitting portion for emitting light to said recording material being held between the second abutment member and the first contact member has the light receiving portion for receiving the light reflected by the irradiated the recording material from the light emitting portion,
The recording material discrimination sensor according to claim 9, wherein the type of the recording material is discriminated based on a light reception result at the light receiving unit. Wherein one of the first contact member and the second abutment member, said transmissive for emitting light to said recording material being held between the second abutment member and the first contact member a light-emitting portion, irradiated from the other one of the first contact member and the second abutment member includes a light emitting portion for reflecting the irradiated light to the recording material, the light emitting unit for transparently are anda light receiving portion for receiving the light reflected by the recording material is irradiated from the light emitting portion for morphism anti and light transmitted through said recording material,
The recording material discrimination sensor according to claim 8 , wherein the type of the recording material is discriminated based on a light reception result at the light receiving unit. The light emitting unit irradiates light to a portion located on the imaginary line in the surface of the recording material sandwiched between the first contact member and the second contact member. The recording material discrimination sensor according to any one of Items 11 to 11. One of the first contact member and the second abutment member, the portion where the light emitted from the light emitting unit passes through the any one of claims 9 to 12 characterized in that it does not contact with the recording medium The recording material discrimination sensor according to item 1.

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