JP4791916B2 - Moisture content measurement structure and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus including the same, and more particularly to detect the moisture state of a sheet-like medium moving on a conveying path in the vicinity of the sheet corresponding to the structure of the conveying path and the movement of the sheet. And an image forming apparatus having the structure.

  The relationship between paper and water in the image forming apparatus is that moisture in the atmosphere is absorbed by the environment where it is left or stored, or water that has been absorbed is emitted, and moisture enters and leaves the paper by fixing and heating.

  This change in the moisture state (moisture content) of the paper causes the paper to expand, roll, wavy, change in strength, and change in electrical resistance, resulting in poor conveyance such as paper jam and double feeding, uneven image density, blurring, and color loss. Cause image defects such as image shift.

  As conventional techniques for solving such conveyance failure and image defect, “image forming apparatus” disclosed in Patent Document 1, “image forming apparatus” disclosed in Patent Document 2, and Patent Document 3 is an “image forming apparatus”.

  The invention disclosed in Patent Document 1 aims to reduce the wasteful energy consumption while ensuring that the temperature and humidity in the apparatus are within a predetermined range suitable for image formation before performing image formation. A temperature sensor for detecting the temperature of the air-conditioned unit inside the apparatus, a humidity sensor for detecting the humidity, an air-conditioning unit for adjusting the temperature and humidity of the air-conditioned unit, and operating the air-conditioning unit at a set time. An air-conditioning control unit that controls the air-conditioning means is provided so that the detected temperature and the humidity detected by the humidity sensor are within a predetermined range. The air-conditioned unit includes the inside of the transfer paper storage unit and the vicinity of the transfer paper transport unit.

  The invention disclosed in Patent Document 2 is provided with a moisture content detecting means for detecting the moisture content of the transfer paper in the conveyance path before transfer inside the image forming apparatus, and detects moisture content exceeding a preset reference value. When the means detects, the transfer paper is securely brought into intimate contact with the image carrier by performing an exhaust operation, and the transfer paper is transferred to the image carrier by the weight of moisture contained in the transfer paper and the weight of the front and rear ends of the transfer paper. Is prevented from being separated from the toner, and defective transfer is prevented.

  The invention disclosed in Patent Document 3 prevents image disturbance and fixing tailing phenomenon when the transfer material is separated from the transfer material carrier while ensuring transferability and separation of the transfer material in the transfer material carrier. An image forming apparatus capable of carrying a toner image on a surface, a transfer unit for transferring a toner image on the image carrier onto a transfer material, and a toner on the transfer material An image having fixing means for fixing an image by heat and pressure, and a post-charging means for charging the transfer material on which the toner image is transferred onto the surface by the transfer means before the toner image is fixed by the fixing means. The forming apparatus has a means for detecting the moisture absorption state of the transfer material, and changes the charging area of the post-charging means according to the detection result of the detecting means. Further, the transfer material has a moisture absorption state detection means, and changes the charging area of the post-charging means according to the detection result of the detection means.

  The inventions disclosed in these Patent Documents 1 to 3 measure the moisture evaporated from the paper surface when the moisture content of the paper is detected by a humidity sensor.

  Moisture that evaporates from the paper is affected by the surrounding environment and diffuses away from the paper surface. Depending on the housing structure of the electrophotographic apparatus and the like, the moisture sensor may need to be disposed at a position away from the paper surface as shown in FIG. Since it is influenced by the surrounding environment before reaching the moisture sensor, the moisture sensor cannot react to the evaporating moisture and is difficult to detect with good reproducibility.

  Therefore, the moisture amount sensor needs to be arranged close to the paper as shown in FIG.

  FIG. 33 shows the state of moisture that evaporates from the paper surface when the paper is stopped. When the paper is stopped and stored in a paper feed tray or the like and the influence of the airflow around the paper is small, the moisture that evaporates can be measured even if the moisture sensor is slightly away from the vicinity of the paper, as shown in FIG. When the paper is being transported, the water that evaporates flows to the rear of the transport, and therefore the moisture that evaporates from the surface of the paper cannot be accurately measured if the moisture sensor is away from the paper. Therefore, as shown in FIG. 35, it is necessary to measure the moisture that evaporates in the vicinity of the paper surface.

  On the other hand, since the moisture sensor is brought close to the conveyed paper, there is a possibility that paper jam will occur when the moisture sensor is fixedly arranged in a narrow conveyance path.

  Further, since the transported and moved paper passes through a plurality of paper feeding devices and is changed in the traveling direction by the transport path, the posture of the paper changes depending on the shape of the transport path. In addition, since the paper to be transported is separated for each sheet, it differs depending on the leading edge / rear edge of the paper, and further, the stiffness and strength of the paper change depending on the moisture condition, paper type, and surrounding environment. Shows trajectory and behavior. For this reason, in the moisture amount sensor installed at a fixed observation point, the detection distance and the detection angle change with respect to the sheet moving in a bent state or a curved state in a different state as shown in FIG. Therefore, there is a problem that a quantitative measurement value with reproducibility cannot be obtained.

  Therefore, a method of incorporating a moisture sensor into the paper feed mechanism itself such as a transport roller that corrects the paper to a fixed position is conceivable. However, there is a paper feed mechanism where it is necessary to measure the moisture that evaporates from the paper. Therefore, the place where it can be installed is limited, and the intended result may not be obtained.

  For this reason, in order to quantitatively obtain the moisture evaporated directly from the paper, including when it is transported and moved, the moisture sensor needs to have a mechanism that can make the detection distance and detection angle constant in the vicinity of the paper surface. The mechanism is not limited to the device configuration, and it must be installed universally.

  As a conventional technique for measuring the state of an object surface during conveyance or movement, a “contact surface temperature sensor” disclosed in Patent Document 4 and a “temperature measuring method and apparatus for a moving surface” disclosed in Patent Document 5 are disclosed. And “Pickup for Video Disc” disclosed in Patent Document 6.

  The invention disclosed in Patent Document 4 relates to a contact-type surface temperature sensor that can be measured by contacting with an optimum contact pressure at the time of measurement of a measurement object that is weak against external force or a measurement object that is moving. The detection part is bent and moved up and down against the undulations on the surface of the object to fix it.

  The invention disclosed in Patent Document 5 is moving, such as a rolled metal plate, a synthetic resin sheet discharged from a nozzle of an extrusion molding machine, and a food intermediate product continuously discharged from a nozzle of a food processing machine. The present invention relates to a method and an apparatus for measuring the temperature of a surface of the object without lightly touching and damaging the object. Specifically, a temperature sensor that is brought into contact with the surface of the moving temperature object to be measured is moored on the moving surface by a flexible connecting member, and is brought into contact with the surface of the temperature object to be measured by the weight of the temperature sensor. A method for measuring the temperature of a moving surface that is designed to move freely according to the surface condition of the temperature object to be measured, a body with guards on both sides, a sled member disposed between the guards, and a sled member A temperature sensor comprising a fixed temperature sensing part, one end of the swing arm is rotatably connected to the temperature sensor, and the other end of the swing arm is rotatably connected to a mooring member. It is the temperature measurement apparatus of the moving surface which moored a temperature sensor on the surface of a to-be-measured body via.

  The invention disclosed in Patent Document 6 uses an elastic body as a material for the cantilever, thereby improving the followability to the surface shake of the rotating disk substrate and performing good reproduction without skipping.

  As a conventional technique related to measuring the surface of a continuous rotating body (endless belt) such as a transfer belt or a conveyance belt, there is an “image forming apparatus” disclosed in Patent Document 7.

The invention disclosed in Patent Document 7 predicts how much the toner image and the paper deviate by detecting a change in the circumferential length of the intermediate transfer belt, and positions the toner image and the paper based on the prediction result. This is to prevent deviations in the relationship.
JP 2005-77762 A JP 2004-219958 A JP 2003-241526 A Japanese Patent No. 3380025 Japanese Patent No. 2741127 Japanese Patent Publication No.58-33602 Japanese Patent No. 3632738

  In the invention disclosed in Patent Document 1, since the temperature sensor and the humidity sensor are not arranged in the vicinity of the paper, the water evaporated from the paper is not measured. Depending on the measured value, the air conditioning is controlled, and in some cases, the originally dried paper may be further dried by the air conditioning control. Therefore, when controlling the paper state, it is necessary to arrange a temperature and humidity sensor near the paper.

  In the invention disclosed in Patent Document 2, since the position is not constant due to the weight of moisture contained in the transfer paper, just installing a moisture content detection sensor in the vicinity of the conveyance path before transfer also takes into account the distance from the transfer paper. In addition, it is not only possible to accurately measure the weight of water contained, but also because the position of the transfer paper is assumed to be not constant due to its own weight, depending on the installation position of the moisture content detection sensor, it becomes an obstacle to the transferred transfer paper, It can also be a factor that causes transfer paper jam.

  In the invention disclosed in Patent Document 3, since the temperature / humidity sensor is disposed outside the conveyance path before image formation (resist part), it is detected in a state where the distance from the paper is large, It is difficult to detect the moisture state of the printed paper.

  In the invention disclosed in Patent Document 4, in order to always contact the detection unit with a constant angle against the displacement of the object surface, there are many complicated bent portions of the detection unit. In order to achieve this, there are many dimensional limitations on the bending location and the bending interval, and accuracy is also required. Moreover, since the detection part must make heat conduction high, it is necessary to lengthen the lead near a contact and to enlarge a contact area. Further, since the detection portion for the support size becomes large in order to secure the amount of bending, it is difficult to arrange in a narrow area such as the paper conveyance path of the image forming apparatus.

  The invention disclosed in Patent Document 5 moves the detection unit up and down depending on the state of the object surface. However, when detecting, it is necessary to first place the detection unit on the object. Since the sheet cannot be disposed in a hollow state without passing through, it cannot be installed in a mechanism that sandwiches and conveys the object to be measured with the facing rollers, such as sheet conveyance of an image forming apparatus.

  The invention disclosed in Patent Document 6 is a mechanism that traces irregularities of fine grooves on the surface of a disk whose posture and position are always constant, and the contact angle is also substantially constant. On the other hand, in order to accurately capture moisture that evaporates vertically from the surface of the paper and to prevent the influence of convection from around the measurement location, the humidity and the position of the paper being transported are not constant, so the humidity is detected. For this purpose, the detection unit must always be constant with respect to the paper surface. Therefore, the support mechanism for detecting and transmitting the state in contact with the surface is not a configuration that can be applied to the sheet conveyance path of the image forming apparatus.

  Some image forming apparatuses change the position of the transfer belt for each printing for the purpose of improving the printing speed during monochrome printing and extending the life of the transfer belt. When trying to measure the temperature / humidity of a transfer belt whose position changes due to such a contact / separation mechanism, the position with the transfer belt changes depending on the printing conditions and the detection distance and detection angle change with a fixed sensor. Therefore, a quantitative measurement value with reproducibility cannot be obtained.

  Since the posture of the paper moving along the conveyance path of the image forming apparatus is diverse, the moisture sensor detects the transpiration moisture from the paper that is discontinuously sent (separated for each sheet) with high reproducibility and high accuracy. For measurement purposes, it can be placed close to the paper, and the detection surface is in surface contact with the paper surface regardless of the orientation of the paper during the transport process, and the fault of the paper being transported (paper surface Damage and paper jams).

  As described above, the conventional mechanism that can quantitatively measure the surface state of the paper with different positions and postures being transported one by one with reproducibility is realized with a configuration that can be arranged in the paper transport path of the image forming apparatus. I couldn't.

  The present invention has been made in view of such a problem, and a mechanism for quantitatively measuring the state of the surface of a sheet having a different position and orientation during conveyance for each sheet with high reproducibility is provided as a sheet conveyance path of an image forming apparatus. It is an object of the present invention to provide a structure for measuring the moisture content of a sheet-like medium realized by a configuration that can be disposed on the image forming apparatus and an image forming apparatus using the structure.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a moisture content measurement structure for detecting moisture that evaporates from the surface of a sheet-like medium that moves along a conveyance path of an image forming apparatus.
The flexible circuit board with the moisture sensor installed at the tip is installed from above so as to block the transport path so that the tip side becomes a free end, and the flexible circuit board is pushed and bent by the sheet-like medium being transported, The present invention provides a moisture content measurement structure in which a moisture content sensor makes surface contact with a sheet-like medium by its own weight.

In order to achieve the above object, according to a second aspect of the present invention, there is provided a moisture content measurement structure for detecting moisture that evaporates from the surface of a sheet-like medium that moves along a conveyance path of an image forming apparatus. A flexible circuit board with a moisture sensor installed at the tip is installed from the bottom so as to block the transport path so that the tip side becomes a free end, and the flexible circuit board is pushed and bent by the sheet-like medium being transported, It is an object of the present invention to provide a moisture content measurement structure in which a moisture sensor comes into surface contact with a sheet-like medium by the elastic force of a flexible circuit board that resists the weight of the moisture sensor.
In the second aspect of the present invention, it is preferable that the flexible circuit board has a weaker elastic force in the vicinity of the tip than an elastic force in the root portion.

  In any configuration of the first or second aspect of the present invention, a guide provided with a sled-like member having a contact area with the sheet-like medium smaller than that of the moisture sensor along the conveying direction of the sheet-like member, It is preferable to attach to a moisture sensor. In addition, a sheet position sensor for detecting the position of the sheet-like medium is preferably provided adjacent to the moisture amount sensor.

  In order to achieve the above object, the present invention provides, as a third aspect, an image forming apparatus provided with the moisture content measuring structure according to any one of the first and second aspects of the present invention. Is.

  According to the present invention, a mechanism for quantitatively measuring the state of the surface of a sheet having a different position and orientation during conveyance for each sheet with high reproducibility is realized with a configuration that can be arranged on a sheet conveyance path of an image forming apparatus. It is possible to provide a moisture content measurement structure for a sheet-like medium and an image forming apparatus using the same.

  A preferred embodiment of the present invention will be described.

[First Embodiment]
FIG. 1 shows a configuration of a moisture content measurement structure (measurement means) according to this embodiment. (A) is a top surface, (b) is a side surface, and (c) is a bottom surface.
The moisture amount sensor 1 has a detection surface area of several mm ² and a minute size. The moisture amount sensor 1 can obtain an accurate measurement value by detecting only moisture that is vertically evaporated from the paper 3. However, since the water evaporated from the paper 3 vertically fluctuates due to the influence of the surrounding air flow while being taken into the detection port 1a of the water content sensor 1, the water content sensor 1 needs to be as close to the paper 3 as possible. is there.
The moisture amount sensor 1 is arranged with signal lines connected so that the distance from the sheet surface can be arbitrarily varied within a certain distance according to the conveyance locus and conveyance conditions of the sheet 3 while the moisture amount can be detected. There is a need to. In maintaining the position of the moisture sensor 1 under such conditions, the configuration (number of parts) for achieving the function is small and can be easily realized, and the atmosphere of moisture evaporation near the paper surface is affected. It is preferable that the structure, shape, and dimensions do not become fluid resistance and can play the role of a signal input / output function.
In order to achieve these functions, in the present embodiment, the measuring means is a sensor support that has the function of making surface contact with the paper 3 by the weight of the moisture sensor 1 and the moisture sensor 1 and inputting and outputting signals. The configuration is composed of part 2. As a result, a configuration for achieving functions such as a link necessary for controlling the posture becomes unnecessary, and the above functions can be easily realized.

  Further, the force for maintaining the posture by the sensor support unit 2 is set such that the moisture sensor 1 comes into surface contact with the paper by its own weight and is parallel to the paper 3. By using a flexible material as the sensor support unit 2, the moisture sensor 1 is brought close to the leading edge of the conveyed paper without causing a paper jam, and the paper is bent or curved while the paper is passing. However, the posture of the moisture sensor 1 can be maintained.

  Specifically, a flexible circuit board in which a copper foil conductive lead is laminated on a flexible polyimide resin film is used as the sensor support portion 2. As shown in FIG. 1, the sensor support 2 opens a portion corresponding to the detection surface of the moisture sensor 1 and connects the detection surface of the moisture sensor 1 so as to face each other. The force for maintaining the posture of the moisture amount sensor 1 by the sensor support unit 2 is a force that allows the surface of the moisture sensor 1 to come into surface contact with the weight of the moisture sensor 1 and is in a range that is parallel to the sheet 3.

  As shown in FIG. 2, a measuring unit having a structure in which the moisture sensor 1 and the sensor support 2 are combined is installed so as to fly in the conveyance direction of the paper 3. As a result, as shown in FIG. 3, the moisture sensor 1 is brought into surface contact with the conveyed paper 3 by its own weight, and the surface contact state is always maintained while the paper is passing.

[Second Embodiment]
The mechanisms such as image forming, transfer, and fixing in the image forming apparatus are arranged and arranged differently depending on the model, and the shape of the paper transport path is also different.
In some cases, such as when detecting moisture that evaporates from the back surface of the paper 3 or from the paper 3 that is not horizontally positioned, it may be better to attach the moisture sensor 1 below the measurement location of the paper 3. For example, when measuring the sheet 3 on which unfixed toner is placed, it is necessary to measure from the side where the toner is not placed (the back side of the sheet 3). Therefore, as in the first embodiment, if the elastic force of the sensor support unit 2 is a force that makes surface contact with the paper 3 by its own weight, depending on the weight of the moisture sensor 1 to be used. As shown in FIG. 4, the distance from the paper 3 may be increased.

  Therefore, it is conceivable to increase the thickness of the sensor support 2 and increase the rigidity (elasticity) so that the moisture sensor 1 does not hang down due to its own weight even if it is attached below the measurement location of the paper 3. . However, with such a structure, the distance between the paper 3 and the moisture sensor 1 is increased as shown in FIG. 5 due to the elastic force of the sensor support 2 with increased rigidity, and it is easily affected by the surrounding environment. In addition, since the detection surface is not in contact with the surface of the paper, reproducible quantitative measurement cannot be obtained. Furthermore, there is a problem that the surface of the paper is damaged by the elastic force of the sensor support portion 2 or paper jam occurs.

  Therefore, the moisture sensor 1 is not only required to have a mechanism that can be disposed close to the paper 3 and the detection surface can be brought into surface contact with the paper surface. It is not necessary to cause troubles in transport (paper surface damage or paper jam).

  For this reason, in order to be able to detect the moisture that evaporates from the back side of the paper, the force for maintaining the posture by the sensor support unit 2 maintains the water content sensor 1 in parallel with the paper 3 and at the same time the water content sensor 1 has its own weight. Therefore, it is necessary to use a force that makes surface contact with the paper. In order to achieve this, the measuring means is composed of a moisture sensor 1 and a sensor support 2 having a signal input / output function, and the sensor support 2 is made of a flexible material and By attaching the same flexible material with different thicknesses and dimensions, a two-step bent portion is provided, and the moisture amount sensor 1 is placed in the vicinity of the back side of the paper or the paper 3 that is not horizontally positioned. .

As a means for giving the sensor support part 2 an acting force that makes contact with the surface of the paper by the weight of the moisture sensor 1, the strength of the sensor support part 2 can be increased while maintaining the flexibility, or a reinforcing member can be used. It is realized by the structure to laminate.
As shown in FIG. 6, the measuring means is composed of a moisture sensor 1 and a sensor support 2 having a signal input / output function. The sensor support 2 is made of a flexible polyimide resin film and copper. A flexible circuit board on which foil conductive leads are laminated is used. Further, the sensor support portion 2 has a structure in which polyimide resin films having different dimensions are laminated to have a two-step bent portion. The distance between the moisture amount sensor 1 and the sheet 3 is made close by the rigidity (elasticity) of the entire sensor support unit 2 (first stage + second stage), and the second stage rigidity (elasticity) with respect to the displacement of the sheet surface. Follow in the lower part. Accordingly, as shown in FIG. 7, the moisture amount sensor 1 can be installed in the vicinity of the back side of the paper or the paper not positioned horizontally.

[Third Embodiment]
Depending on the image forming apparatus that handles paper conveyed at high speed, when the moisture amount sensor 1 is disposed close to the paper, the detection unit wears out, so that the wear surface is made as small as possible and the friction coefficient is small. It is necessary to form with.

  For this reason, the measuring means is composed of a moisture sensor 1, a sensor support 2 having a signal input / output function, and a guide 4, and the moisture sensor 1 is spaced from the conveyed paper 3 by the guide 4. By separating with, the wear of the detection part is prevented. At this time, if the contact surface is made as small as possible and made of a material having a small friction coefficient, the measurement performance is not impaired.

  In order to prevent the detection portion from being worn, the contact surface is made of a material having as small a friction coefficient as possible. The measuring means does not generate a paper jam and has an inclined surface or an R surface for preventing the paper jam as shown in FIG. 8 so that the surface of the paper 3 and the moisture sensor 1 can be separated. It is set as the structure which provided the guide 4 of the provided shape. As shown in FIG. 9, the guide 4 is attached to the sensor support portion 2.

  The moisture amount sensor 1 passing through the paper can keep a constant distance from the paper surface by the rigidity (elasticity) of the sensor support 2 and the guide 4.

  In the case where moisture that evaporates from the back surface of the paper 3 or from the paper 3 that is not positioned horizontally is detected, the moisture is separated from the back surface of the paper due to the weight of the moisture sensor 1 and the guide 4 and cannot be installed in the vicinity. As in the second embodiment, the strength of the material of the sensor support 2 is maintained while increasing the strength, or by using the sensor support 2 having a two-step bent portion, The distance should be kept constant.

  The moisture that evaporates from the surface of the paper is greatly fluctuated due to the influence of the surrounding air current. Therefore, the distance between the detection surface of the moisture sensor 1 and the surface of the paper is set to 1 mm or less, and only the moisture that evaporates vertically from the paper 3 is detected. As a result, an accurate measurement value can be obtained.

  As shown in FIG. 10, a measuring unit having a structure in which the moisture sensor 1, the sensor support 2, and the guide 4 are combined is installed so as to fly in the conveyance direction of the paper 3. Accordingly, as shown in FIGS. 11 and 12, the moisture amount sensor 1 is brought close to the conveyed paper 3, and the detection surface is always opposed to the paper 3 in the vertical direction.

  In addition, as shown in FIG. 13, when it is desired to connect the detection surface of the moisture sensor 1 without facing the sensor support portion 2, an inclined surface or R surface for preventing the occurrence of paper jam as shown in FIG. By using the guide 4 having the shape provided, the distance between the paper surface and the moisture amount sensor 1 passing through the paper is kept constant by the rigidity (elasticity) of the sensor support portion 2 and the guide 4. Similarly, the distance between the moisture sensor 1 and the paper surface is set to 1 mm or less. The guide 4 is attached to the sensor support portion 2 as shown in FIG.

  A measuring means having a structure in which the moisture amount sensor 1, the sensor support portion 2, and the guide 4 are combined is installed so as to fly in the paper transport direction as shown in FIG. As a result, as shown in FIGS. 17 and 18, the moisture sensor is brought close to the conveyed paper, and the detection surface is always faced in the vertical direction with respect to the paper.

  Further, as an application example, when used for measuring the moisture state of the surface of a continuous rotating body such as a transfer belt, the guide 4 to be used has a shape having an R surface as shown in FIG. 19, and the guide 4 is shown in FIG. As shown, the sensor support 2 is mounted. The size of R is determined according to the shape of the measurement object. As a result, as shown in FIG. 21, the posture of the moisture amount sensor 1 can be maintained constant even when the transfer belt is curved.

[Fourth Embodiment]
The moisture sensor 1 is sufficiently accustomed to the environment and unheated paper that has not passed through the fixing device may be indistinguishable from when paper 3 has not passed.
Further, in the heated paper that has passed through the fixing device, there is a problem that the moisture amount sensor 1 cannot distinguish whether it is transpiration moisture while the paper is passing or whether the transpiration moisture remains or remains after the paper has passed.
Furthermore, when measuring the distribution of each moving sheet, or when measuring only a specific part of the sheet 3 with points as shown in FIG. 22, the timing at which the sheet 3 starts to pass the moisture amount sensor 1 is set. Need to be identified.

  Therefore, it is necessary to obtain a timing when the transported paper 3 passes the position of the moisture sensor 1. However, when measuring the transpiration moisture from a specific location on the paper 3, the paper 3 moving in the paper transport system is measured. It is difficult to accurately specify the location of the paper 3 only with the moisture sensor 1 installed at a fixed observation point.

  A specific location of the paper at the location where the moisture sensor 1 is installed by combining the transport distance between the location where the paper position sensor 5 is installed and the moisture sensor 1 where the conventional is installed, with the transport speed of the transport roller. However, when the moisture amount sensor 1 is arranged at a location where the posture of the paper is changed by conveyance, the paper is bent and deformed by the conveyance path as shown in FIG. It was difficult to measure.

  Furthermore, since the paper 3 expands and contracts due to the release of moisture while the paper 3 is undergoing the process, if the installation location of the paper position sensor 5 and the installation location of the moisture sensor 1 are separated, the location of the paper 3 It becomes difficult to accurately identify Note that the expansion and contraction of the sheet 3 inevitably causes image misalignment and various measures have been taken, and the expansion and contraction of the sheet 3 is inevitable.

  For this reason, the paper position sensor 5 needs to be disposed at the same location as the moisture sensor 1 in order to measure the time required for the moving paper 3 to pass the position of the moisture sensor 1 with high reproducibility and high accuracy.

  In the present embodiment, the measuring means includes a moisture amount sensor 1, a paper position sensor 5, a sensor support unit 2 having a signal input / output signal function, and a guide 4. By arranging it at the same location as the amount sensor 1, it is possible to measure the time required for the moving paper 3 to pass the position of the moisture amount sensor 1 with high reproducibility and high accuracy.

  The paper position sensor 5 can be mounted at the same location as the moisture amount sensor 1 so that the timing when the conveyed sheet 3 passes the location of the moisture amount sensor 1 is made clear. Further, as shown in FIG. By arranging in parallel with the paper position sensor 5, the timing from the leading edge to the trailing edge of the conveyed paper 3 can be accurately measured at the position of the moisture sensor 1.

  FIG. 25 shows an example in which the moisture that evaporates from the surface of the conveyed paper is measured. When installed at a conventional fixed observation point and the distance from the paper 3 is far away, most of them only measure the environment around the moisture sensor 1, so that the moisture that evaporates from the surface of the paper being conveyed is removed. It cannot be measured accurately. In addition, when it is in the vicinity but is installed at a fixed observation point, the angle of the detection surface is constant while the posture of the paper 3 changes, so the distance between the paper surface and the moisture sensor is It changes with attitude.

Accordingly, the response of the moisture sensor 1 increases when the distance from the sheet 3 is short, and decreases when the distance is away from the sheet 3, so that it is in a swaying state, and moisture that evaporates from the surface of the sheet being conveyed cannot be measured accurately.
In the present embodiment, since the moisture amount sensor 1 can make the detection distance and posture constant with respect to various paper postures, the water evaporated from the paper 3 can be measured with high reproducibility and high accuracy.

[Fifth Embodiment]
Next, a case where the result obtained by the measuring unit according to the above embodiment is developed to control the image forming apparatus will be described with reference to FIGS.
By changing the arrangement of measurement means and judgment criteria (necessary information), it can be developed to control various devices. The first measurement means 11 to the fifth measurement means 15 shown in FIG. 26 mean installation positions necessary for each control, and the paper feed tray 101, the image forming front part 102, and the fixing front part 103 shown in FIG. The measuring unit is disposed in the fixing rear portion 104 and the reversing unit 105.

  The first measuring means 11 is installed in the paper feed tray 101 for the purpose of controlling an environmental control device (such as a heater or a fan) installed in the paper feed tray 101, and when the paper starts to be conveyed. Measure. The first measuring means 11 has an installation structure as shown in FIG. 3, FIG. 11, FIG. 17, etc. with respect to the paper surface where the paper surface in the paper feed tray 101 is picked up.

  The second measuring means 12 is installed at the image forming front part 102 (the position of the sheet immediately before the image is formed) for the purpose of controlling the transfer bias device. The second measuring means 12 has an installation structure as shown in FIGS. 3, 7, 11, 17, 12, 18, etc. with respect to the paper surface of the portion that travels in the conveyance path.

  The third measuring means 13 is installed in the fixing front portion 103 (the position of the sheet immediately before the image is fixed) for the purpose of controlling the fixing device (fixing temperature control and fixing portion conveyance speed control). Since the unfixed toner is on the paper in the fixing front portion 103, the third measuring unit 13 has an installation structure as shown in FIGS. 7, 12, and 18 with respect to the back surface of the paper. .

  For the purpose of controlling the fixing fan, the fourth measuring means 14 is installed at the fixing rear portion 104 (the position of the sheet immediately after the image is fixed). The fourth measuring means 14 has an installation structure as shown in FIG. 3, FIG. 11, FIG.

  At the time of duplex printing, it is necessary to reverse the paper and return to the image forming process. The fifth measuring means 15 is installed in the reverse rear part 15 for the purpose of controlling the reverse fan. The reverse rear portion 15 has an installation structure as shown in FIGS. 3, 7, 11, 17, 12, 18, etc. with respect to the paper surface of the portion that travels in the conveyance path.

The measuring means 11 to 15 are installed at locations in the target image forming apparatus, and the result of measuring the moisture evaporated from the paper 3 passing through the portion is input to the CPU 20 (processing device), and the basic information storage unit 21 Control is performed by calculating an optimal control value in comparison with various information stored in advance.
In addition, a warning signal is output to the warning unit 35 when the control result is out of the control range.

  FIG. 28 is a flowchart showing from measurement using the first measurement means 11 to device control. After turning on the power of the image forming apparatus (step S1), the CPU 20 acquires data at the timing stored in the basic information storage unit 21 (step S2), and the data acquired from the first measuring unit 11 is the basic information. It is determined whether it is within the set range stored in the storage unit 21 (step S3). When the measured value obtained by the first measuring unit 11 is out of the setting range, the CPU 20 controls the heater / fan control unit 31 to drive the fan and heater arranged in the paper feed tray 101. (Step S4). The CPU 20 continues to drive the fan and heater until the measurement is repeated within the set range. When the measurement result falls within the set range, the CPU 20 controls the heater / fan control unit 31 to stop the fan and the heater (step S6).

  If the result of step S3 is within the set range, the CPU 20 continuously performs measurement (step S2). The measurement and device control from step S2 to step S6 are continuously repeated until the device power is turned off (step S7).

  FIG. 29 is a flowchart showing from measurement using the second measurement unit 12 and the third measurement unit 13 to device control. After the print command is input to the image forming apparatus, the conveyance of the paper is started (step S8). When the paper position sensor mounted on the measuring means detects that the leading edge of the conveyed paper starts to pass through the measuring means (step S9), it is input to the CPU 20 and the time of the time measuring unit 22 is cleared (step S10). Thereafter, the measurement means starts measurement and acquires data at a timing stored in advance in the basic information storage unit 21 (step S11). When it is detected by the paper position sensor that the paper has passed the measuring means (step S12), the CPU 20 ends the measurement by the measuring means and stores the measured value obtained by the measuring means and the basic information storage unit 21. Control values of the transfer bias control / conveyance speed control unit 32, the fixing temperature control / fixing unit conveyance control unit 33, and the like are calculated (step S13) based on each basic information. The calculated result is determined (step S14), and if it is within the control range, the process control is performed using the calculated result (step S15). Further, when it is out of the control range, a warning signal is output to the warning section (step S16).

FIG. 30 is a flowchart showing from measurement to device control using the fourth measurement means and the fifth measurement means. After the print command is input to the image forming apparatus, the conveyance of the sheet 3 is started (step S17). When the fans installed in the fixing rear portion 104 and the reversing unit 105 are stopped, the CPU 20 drives the fans (step S18). When the paper position sensor mounted on the measuring means detects that the trailing edge of the conveyed paper 3 starts to pass through the measuring means (step S19), it is input to the CPU and the time of the time measuring unit 22 is cleared (step S20). ).
Thereafter, measurement by the measuring means is started, and data is acquired at the timing stored in advance in the basic information storage unit 21 (step S21). The CPU 20 compares the measured value obtained by the measuring means with the set value stored in the basic information storage unit 21 (step S22). If it is within the set range, the measurement by the measuring means is terminated and the fan is stopped. (Step S23). On the other hand, when it is out of the set range, measurement is repeatedly performed by the measurement means (step S21).

  The image forming apparatus according to the present embodiment can quantitatively measure the state (transpiration moisture) of the surface of a sheet having a different position and posture during conveyance in the sheet conveyance path with good reproducibility.

  Each of the above embodiments is an example of a preferred embodiment of the present invention, and the present invention is not limited to these and can be variously modified.

It is a figure which shows the structure of the moisture content detection structure concerning 1st Embodiment which implemented this invention suitably. It is a figure which shows a mode that a sensor support part bends with the paper conveyed. It is a figure which shows the state in which the moisture sensor is in surface contact with the paper by its own weight. It is a figure which shows the state which has arrange | positioned the moisture content detection structure concerning 1st Embodiment under the conveyance path | route (elastic weakness of a sensor support part). It is a figure which shows the state which has arrange | positioned the moisture content detection structure concerning 1st Embodiment under the conveyance path | route (elastic strength of a sensor support part). It is a figure which shows the structure of the moisture content detection structure concerning 2nd Embodiment which implemented this invention suitably. It is a figure which shows the state in which the moisture amount sensor surface-contacted with the paper with the elastic force of the sensor support part. It is a figure which shows the shape of the guide used for the moisture content detection structure concerning 3rd Embodiment which implemented this invention suitably. It is a figure which shows the state which mounted | wore the sensor support part with the guide. It is a figure which shows a mode that a sensor support part bends with the paper conveyed. It is a figure which shows the state which the guide contacted the paper so that a moisture amount sensor might become parallel to the paper. It is a figure which shows the state which the guide contacted the paper so that a moisture amount sensor might become parallel to the paper. It is a figure which shows the connection state of the moisture sensor and sensor support part when not making the detection surface of a moisture sensor face the sensor support part. It is a figure which shows the shape of the guide used when the detection surface of a moisture sensor is not made to face a sensor support part. It is a figure which shows the structure of the moisture content measurement structure when not making the detection surface of a moisture content sensor face a sensor support part. It is a figure which shows a mode that a sensor support part bends with the paper conveyed. It is a figure which shows the state which the guide contacted the paper so that a moisture amount sensor might become parallel to the paper. It is a figure which shows the state which the guide contacted the paper so that a moisture amount sensor might become parallel to the paper. It is a figure which shows the shape of a guide in case a measuring object is an endless belt. It is a figure which shows the structure of the moisture content measurement structure in case a measuring object is an endless belt. It is a figure which shows the state by which the moisture amount detection sensor was arrange | positioned close to an endless belt. It is a figure which shows the measurement point of a paper. It is a figure which shows the behavior of the conveyed paper. It is a figure which shows the structure of the moisture content measuring structure concerning 4th Embodiment which implemented this invention suitably. It is a figure which shows the difference in the detection result by arrangement | positioning of a moisture content sensor. It is a figure which shows the function structure of the image forming apparatus concerning 5th Embodiment which implemented this invention suitably. It is a figure which shows schematic structure of the image forming apparatus concerning 5th Embodiment which implemented this invention suitably. 10 is an apparatus control flow using a first measurement unit of an image forming apparatus according to a fifth embodiment. 10 is an apparatus control flow using a second or third measuring unit of an image forming apparatus according to a fifth embodiment. 10 is an apparatus control flow using a fourth or fifth measuring unit of an image forming apparatus according to a fifth embodiment. It is a figure which shows that a detection precision falls as the distance of a moisture sensor and a paper leaves | separates. It is a figure which shows that detection accuracy improves by making a moisture content sensor adjoin to a paper. It is a figure which shows the water | moisture content evaporating from the paper surface of a stationary state. It is a figure which shows the water | moisture content transpired from the paper in movement. It is a figure which shows the relationship between the water | moisture content transpired from the paper currently moving, and detection distance. It is a figure which shows the relationship between the paper in conveyance and detection distance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Moisture content sensor 2 Sensor support part 3 Paper 4 Guide 5 Paper position sensor

Claims (6)

A moisture content measurement structure for detecting moisture that evaporates from the surface of a sheet-like medium that moves along a conveyance path of an image forming apparatus,
A flexible circuit board with a moisture sensor installed at the tip is installed from above so as to block the transport path so that the tip side becomes a free end,
The moisture content measuring structure, wherein the flexible circuit board is pushed and bent by the conveyed sheet-like medium, and the moisture sensor comes into surface contact with the sheet-like medium by its own weight. A moisture content measurement structure for detecting moisture that evaporates from the surface of a sheet-like medium that moves along a conveyance path of an image forming apparatus,
A flexible circuit board with a moisture sensor installed at the tip is installed from below so as to block the transport path so that the tip side becomes a free end,
The flexible circuit board is pushed and bent by the conveyed sheet-like medium, and the moisture sensor comes into surface contact with the sheet-like medium by the elastic force of the flexible circuit board against the weight of the moisture sensor. Moisture content measurement structure characterized by that.   The moisture measurement structure according to claim 2, wherein the flexible circuit board has an elastic force in the vicinity of a tip thereof that is weaker than an elastic force at a base portion.   The guide provided with a sled-like member whose contact area with the sheet-like medium is smaller than the moisture amount sensor along the conveying direction of the sheet-like member is mounted on the moisture amount sensor. The moisture content measurement structure according to any one of 1 to 3.   5. The moisture content measuring structure according to claim 1, wherein a sheet position sensor for detecting the position of the sheet-like medium is provided adjacent to the moisture content sensor.   An image forming apparatus comprising the moisture content measuring structure according to claim 1.

Images