JP5094511B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus including the same.

  A conventional image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multi-function machine forms a toner image on a recording material such as paper in an image forming unit, for example, and this is fixed by a fixing device. By fixing on the recording material, an image is formed on the recording material.

  Among such conventional image forming apparatuses, an image forming apparatus that forms an image by an electrophotographic image forming process, for example, charges the surface of an image carrier such as a photosensitive member with a charging device, and exposes the charged area to the exposure device. The image is exposed to form an electrostatic latent image, the electrostatic latent image is developed by a developing device, and the toner image formed is electrostatically transferred to a recording material by a transfer device. The toner image transferred onto the recording material is heated and fixed by a fixing device to form an image on the recording material.

  In such a conventional image forming apparatus, an exchange member (for example, a developing unit in which the developing device is detachable from the image forming apparatus, or a part of functional members of the image forming process is unitized into the image forming apparatus. When replacing a unit part such as a process unit that can be attached and detached (hereinafter referred to as a unit member) according to its service life, the usage time or the number of printed sheets of the unit part is counted, and when the count value reaches the upper limit, An alarm that prompts the user to replace the unit parts is issued (for example, a warning is displayed). When an unused unit part is installed, it is detected that the unused unit part is installed, and the counter is automatically countered. The unit component usable status is managed by resetting.

  In this case, whether or not the unit part is an unused product is determined, for example, by detecting the difference between the disconnection and non-disconnection of the fuse provided to determine it, or when the unit part is mounted on the image forming apparatus. This is performed by detecting a displacement state of a mechanical component configured to be displaced using a detection member such as a sensor or a switch.

  However, in such a conventional configuration, it is necessary to separately provide a member such as a fuse or a sensor for detecting whether or not the product is an unused product, which increases the number of components, which further increases the complexity of the device configuration and the device. Leads to an increase in size.

  Also, the fixing device is usually a unit part that is replaced according to its life (for example, a fixing unit in which the fixing device is detachable from the image forming apparatus), and whether or not the unit part is an unused product is determined in the image forming apparatus. A mechanism is required to make the determination. However, when the conventional configuration as described above is adopted, there is a problem in that the configuration of the device is complicated and the size of the device is increased, and a fuse is used to detect whether the product is unused. Since the entire fixing device is at a high temperature when the is used, there are various restrictions such as an influence on the fuse due to the high temperature.

  The present invention relates to a fixing device provided in an image forming apparatus and an image forming apparatus provided with the fixing device, wherein the fixing device does not separately provide a member such as a fuse or a sensor for detecting whether the product is an unused product. Whether or not it is an unused product can be detected, so that the number of parts does not increase even if it is detected whether or not it is an unused product, and therefore it is possible to prevent the device configuration from becoming complicated and the device from becoming larger. It is an object of the present invention to provide a fixing device and an image forming apparatus including the same.

In addition, there exists a thing of the following patent document 1 as a reference relevant to the technique of this invention mentioned later. That is, Patent Document 1 discloses a fixing device including a holder made of a shape memory alloy that is deformed so as to maintain a contact state between the temperature detection element and the heat roller when the temperature of the heat roller rises. .
JP-A-1-982

  In order to solve the above problems, the present invention provides the following fixing device and image forming apparatus.

(1) Fixing device The fixing device provided in the image forming apparatus includes a fixing roller to be heated and a temperature sensor for measuring a surface temperature of the fixing roller, and the temperature sensor at the initial stage of heating the fixing roller. The measurement temperature characteristic is configured to be different between an unused product and a used product of the fixing device , the temperature sensor is supported at an initial position separated from the fixing roller, and the temperature of the fixing roller is increased. A support part that is deformed and moved from the initial position toward a measurement position for measuring the surface temperature of the fixing roller, and when the temperature sensor moves to the measurement position at the support part, the temperature is moved to the measurement position. A fixing device comprising: a latch portion for fixing the sensor so as to maintain the sensor .

(2) Image forming apparatus The image forming apparatus includes the fixing device according to the present invention and a control unit that detects a measured temperature characteristic of the temperature sensor based on a measurement output of the temperature sensor, and the control unit detects the temperature sensor. An image forming apparatus comprising: determining whether the fixing device is an unused product based on a measured temperature characteristic.

In the fixing device according to the present invention, the measurement temperature characteristic of the temperature sensor at the initial stage of heating the fixing roller is configured to be different between the unused product and the used product of the fixing device. There is no need to separately provide a member such as a fuse or a sensor for detecting whether or not. Thereby, even if it is detected whether it is an unused article, the number of parts does not increase, and accordingly, it is possible to prevent the apparatus configuration from becoming complicated and the apparatus from being enlarged.
Specifically, the support portion supports the temperature sensor at the initial position separated from the fixing roller in an initial state (for example, an unused product at the time of factory shipment). On the other hand, the support portion is deformed as the temperature of the fixing roller rises, and the temperature sensor is moved from the initial position toward the fixing roller to the measurement position (typically a position in contact with the surface of the fixing roller). The latch portion is fixed so as to maintain the temperature sensor at the measurement position. When the temperature sensor is located at the initial position when the fixing roller is heated, the temperature can be measured by the temperature sensor as an unused product of the fixing device. Further, when the temperature sensor is fixed at the measurement position when the fixing roller is heated, the temperature can be measured by the temperature sensor as a used product of the fixing device. As a result, the measured temperature characteristics of the temperature sensor at the initial stage of heating the fixing roller can be made different between an unused product and a used product.

  Further, in the image forming apparatus according to the present invention, the control unit detects a measured temperature characteristic of the temperature sensor based on a measurement output of the temperature sensor, and the fixing device detects the measured temperature characteristic detected by the temperature sensor. Since it is determined whether or not it is an unused product, utilizing the difference in the measured temperature characteristics of the temperature sensor at the initial stage of heating the fixing roller with respect to the unused product and the used product of the fixing device according to the present invention, It is possible to detect whether or not the fixing device is an unused product. As this measurement temperature characteristic, the characteristic which shows the relationship between the measurement output value by the said temperature sensor and measurement elapsed time can be illustrated. An example of the initial heating period for the fixing roller is a period from when the fixing roller is heated until a predetermined fixing temperature is reached.

  In the fixing device according to the present invention, specific examples of the latch portion include the following. That is, the latch part includes a claw for fixing the temperature sensor and an elastic member that supports the claw, and the claw prevents the return deformation of the support part due to a temperature drop. A fixing portion for fixing the fixing portion at the measurement position, and the fixing portion against the elastic force of the elastic member when the temperature sensor moves from the initial position to the measurement position due to deformation due to a temperature rise of the support portion. And a retracting unit that retracts and allows the temperature sensor to move to the measurement position.

  In this specific matter, the initial position is a simple holding mechanism in which the retraction portion of the claw retreats the fixing portion against the elastic force of the elastic member by utilizing deformation due to a temperature rise of the support portion. The temperature sensor that moves from the measurement position to the measurement position can be automatically and reliably fixed at the measurement position by the fixing portion of the claw.

  In the fixing device according to the present invention, examples of the support portion include those made of shape memory alloy or bimetal.

  According to this specific matter, the support unit reliably positions the temperature sensor at the initial position at room temperature in the initial state (when the fixing roller is not heated) and at a high temperature (the When the fixing roller is heated), the temperature sensor can be deformed as the temperature rises, and the temperature sensor can be stably moved from the initial position to the measurement position, whereby a stable measurement temperature of the temperature sensor can be obtained. Characteristics can be obtained.

  In the fixing device according to the present invention, it is preferable that a cover that shields the latch portion and the support portion from the outside is provided.

  According to this specific matter, it is possible to prevent an operator who replaces the fixing device from inadvertently touching the latch portion and the support portion.

  Further, in the image forming apparatus according to the present invention, the control unit determines whether or not the fixing device is an unused product based on a gradient of the measurement output value of the temperature sensor (a change amount of the measurement output value per unit time). A mode of determination can be exemplified.

  According to this specific matter, it is possible to detect whether or not the fixing device is an unused product with a simple control configuration.

  In this case, as a more specific aspect, the control unit detects that the gradient of the measurement output value of the temperature sensor (the amount of change in the measurement output value per unit time) is greater than or equal to the predetermined value within a predetermined time. In this case, it is possible to exemplify a mode in which it is determined that the fixing device is an unused product.

  In the image forming apparatus according to the present invention, the control unit may determine that the gradient of the measurement output value of the temperature sensor (the amount of change in the measurement output value per unit time) is equal to or greater than the predetermined value even if the predetermined time is exceeded. An example of determining that the fixing device is in failure when there is no failure can be exemplified.

  According to this specific matter, it is possible to detect that the fixing device is out of order with a simple control configuration.

  As described above, according to the fixing device and the image forming apparatus including the same according to the present invention, the fixing device is not provided without separately providing a member such as a fuse or a sensor for detecting whether the product is an unused product. Whether it is a used product or not can be detected, so that the number of parts does not increase even if it is detected whether it is an unused product, thus preventing the device configuration from becoming complicated and the device from becoming larger. Is possible.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

[Overall configuration of fixing device]
First, a fixing device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view schematically showing a configuration of a fixing unit 27 which is an example of a fixing device according to the present invention. The fixing unit 27 is detachable from the electrophotographic image forming apparatus 100 (see FIG. 4 described later).

  As shown in FIG. 1, the fixing unit 27 includes a heating roller (an example of a fixing roller) 123 and a pressure roller 124 disposed so as to face the heating roller 123.

  The heating roller 123 is heated by the fixing heaters 128 and 129. The pressure roller 124 is pressed toward the heating roller 123 by a pressing unit (not shown). A fixing nip portion α is formed at a pressure contact portion between the heating roller 123 and the pressure roller 124. The heating roller 123 and the pressure roller 124 are configured to rotate in the transport direction (the arrow X direction in the figure) for transporting the recording material P such as recording paper. Here, the heating roller 123 is rotationally driven in a predetermined rotation direction (arrow counterclockwise direction A in the figure), and the pressure roller 124 is driven to rotate in a direction opposite to the rotation direction A (arrow clockwise direction B in the figure). It has come to be. As a result, the fixing unit 27 conveys the toner on the recording material P by conveying the recording material P onto which the toner image has been transferred while being sandwiched by the nip portion α between the heating roller 123 and the pressure roller 124. The recording material P can be pressure-fixed by heating and melting.

  Specifically, the heating roller 123 has a configuration in which an elastic layer 123b is provided on the outer peripheral surface of a cylindrical metal core 123a, and a fixing heater (in this case, a main heater 128 and a sub heater 129 made of a halogen heater lamp). have.

  A temperature sensor 130 is provided around the heating roller 123. Here, the temperature sensor 130 is a contact type thermistor. The fixing temperature of the surface of the heating roller 123 (temperature when image formation is performed) is 160 ° C. to under the instruction of the control unit 200 (see FIG. 5 described later) in the image forming apparatus 100 based on the measurement output of the temperature sensor 130. The main heater 128 and the sub heater 129 are controlled so as to be in the range of 200 ° C.

  Similarly to the heating roller 123, the pressure roller 124 is configured such that an elastic layer 124b is provided on the outer peripheral surface of a cylindrical metal core 124a. In the present embodiment, the pressure roller 124 also has a fixing heater (here, a pressure roller heater 138 made of a halogen heater lamp) inside.

  In the present embodiment, the peeling claw 135A is located near the downstream side of the fixing nip portion α in the rotation direction A of the heating roller 123, and the downstream side of the fixing nip portion α is located near the downstream side of the fixing nip portion α in the rotational direction B of the pressure roller 124. The peeling claws 135 </ b> B are in contact with each other so that the recording material P subjected to the fixing process does not wind around the heating roller 123 or the pressure roller 124.

  In the present embodiment, the fixing unit 27 includes a web sheet type cleaning unit 131 that wipes off residual toner adhering to the outer peripheral surface of the heating roller 123 in addition to the above-described configuration.

  The cleaning unit 131 is provided on the upstream side of the temperature sensor 130 and the downstream side of the fixing nip portion α in the rotation direction A of the heating roller 123, and the web sheet sending roller 132 around which the web sheet 133 is wound, A tension roller 134 for applying a predetermined tension to the web sheet 133 drawn from the web sheet feed roller 132, a pressure roller 136 for pressing the web sheet 133 against the outer peripheral surface of the heating roller 123, and a used web sheet 133 are wound up. A winding roller 137.

  The cleaning unit 131 is a regular replacement part that is replaced according to a predetermined replacement cycle. When the replacement cycle arrives, the fixing unit 27 is replaced together with other parts.

[Description of Features of Fixing Device According to the Present Invention]
In the fixing unit 27 according to the embodiment of the present invention, the measured temperature characteristics (temperature measurement state) of the temperature sensor 130 at the initial stage of heating the heating roller 123 are different between the unused product and the used product of the fixing unit 27. It is configured as follows.

  Specifically, the fixing unit 27 includes a support portion 271 and a latch portion 272 in addition to the heating roller 123 and the temperature sensor 130 described above.

  FIG. 2 is an explanatory view showing, in an enlarged manner, the temperature sensor 130, the support portion 271 and the latch portion 272 shown in FIG. 3 is a state transition diagram of the temperature sensor 130, the support portion 271 and the latch portion 272 shown in FIG. 2, and FIG. 3A shows a state where the temperature sensor 130 is located at the initial position. 3B shows a state in which the temperature sensor 130 shifts from the initial position to the measurement position, and FIG. 3C shows a state in which the temperature sensor 130 is located at the measurement position. ing.

  The support unit 271 supports the temperature sensor 130 at an initial position (see FIGS. 2 and 3A) separated from the heating roller 123 when the fixing unit 27 is an unused product at the time of shipment from the factory. Yes.

  Further, the support portion 271 is deformed as the temperature of the heating roller 123 rises, and the temperature sensor 130 is measured from the initial position to measure the surface temperature of the heating roller 123 (here, shown in FIG. 3C). Thus, it is moved toward a position in contact with the surface of the heating roller 123 (hereinafter referred to as a contact position). Here, the temperature at which the support portion 271 is deformed to move the temperature sensor 130 to the contact position is set to about 100 ° C. here.

  The latch portion 272 is fixed to maintain the temperature sensor 130 at the contact position when the temperature sensor 130 is moved from the initial position to the contact position by the support portion 271.

  When the temperature sensor 130 is located at the initial position before the heating roller 123 is heated, the temperature measurement is performed by the temperature sensor 130 as an unused product of the fixing unit 27. Further, when the temperature sensor 130 is fixed at the contact position before the heating roller 123 is heated, the temperature measurement is performed by the temperature sensor 130 as a used product of the fixing unit 27. Thereby, the measurement temperature characteristic of the temperature sensor 130 in the initial stage of heating to the heating roller 123 can be made different between the unused product and the used product.

  Specifically, the support portion 271 is made of a shape memory alloy or bimetal. The support portion 271 is a plate-like member along the axial direction of the heating roller 123, and a base end portion 271a is fixed to the fixing device main body. Further, the support portion 271 extends from the base end portion 271a toward the heating roller 123 in an initial state (for example, a state of an unused product at the time of factory shipment), and gradually increases from the middle toward the distal end portion 271b. It is curving in a direction gradually separating from 123, and the distal end portion 271b is a free end portion. A temperature sensor 130 is provided at the tip 271b. The support portion 271 is heated by an increase in the ambient temperature due to the temperature rise of the heating roller 123, is deformed to the heating roller 123 side by the temperature rise due to this heating, and the temperature detection portion 130a of the temperature sensor 130 provided at the tip portion 271b is It contacts the heating roller 123. The support portion 271 is provided with a through hole 271c through which a claw 273 described later passes.

  In the present embodiment, the latch portion 272 includes a claw 273 and an elastic member 274 that supports the claw 273. The claw 273 has a function of fixing the temperature sensor 130 at the measurement position.

  The claw 273 includes a fixing portion 273a and a retracting portion 273b. As shown in FIG. 3C, the fixing portion 273a fixes the temperature sensor 130 at the contact position so as to prevent the return deformation of the support portion 271 due to a temperature drop. As shown in FIG. 3B, the retracting portion 273b is an elastic member while being in sliding contact with the support portion 271 when the temperature sensor 130 is moved from the initial position to the contact position due to deformation due to the temperature rise of the support portion 271. The fixing portion 273a is retracted to a retracted position where the temperature sensor 130 is not fixed to the contact position against the elastic force of 274, thereby allowing the temperature sensor 130 to move to the contact position. When the temperature sensor 130 is located at the contact position, the retracting operation to the retracted position by the retracting portion 273b is released as shown in FIG. 3C, and the fixing portion 273a is heated by the elastic force of the elastic member 274. The sensor 130 is moved to be fixed at the contact position (here, the temperature sensor 130 is fixed at the contact position and pressed toward the heating roller 123).

  Specifically, as shown in FIG. 3C, the fixing portion 273a is an engagement surface that engages with the side surface of the support portion 271 opposite to the heating roller 123 side in a state where the temperature sensor 130 is fixed. Yes. Further, here, the retracting portion 273b is provided adjacent to the fixing portion 273a on the tip side of the fixing portion 273a. The retracting portion 273b is an inclined surface that is inclined so that the fixing portion 273a is retracted to the retracted position with respect to the supporting portion 271 while being in sliding contact with the supporting portion 271. In the state shown in FIGS. 2 and 3A, the retracting portion 273b is located at a position where the tip end portion 273b ′ is displaced with reference to the contact surface 271c ′ of the support portion 271 (here, the inner periphery of the through hole 271c). The boundary end portion 273b ″ with the fixed portion 273a is on the opposite side of the tip portion 273b ′ with respect to the contact surface 271c ′ of the support portion 271. It is configured to be located at a displaced position (here, a position corresponding to the outside of the inner peripheral surface 271c ′ of the through hole 271c).

  In the elastic member 274, the retracting member 273b is in sliding contact with the contact surface of the support portion 271 (here, the inner peripheral surface of the through hole 271c) 271c ′ as the support portion 271 moves toward the heating roller 123 due to temperature rise. The fixing portion 273a is retracted to the retracted position and has an elastic force enough to allow the temperature sensor 130 to move to the contact position. When the temperature sensor 130 is located at the contact position, the elastic member 274 releases the retreat operation to the retreat position by the retreat portion 273b, and the fixing portion 273a causes the temperature sensor 130 to move to the contact position by the elastic force of the elastic member 274. Has a pressing surface 247 ′ that presses the contact surface 271c ′ of the support portion 271 (here, the inner peripheral surface of the through-hole 271c) so as to press it toward the heating roller 123. 2 and FIG. 3A, the elastic member 274 has a pressing surface 247 ′ as a boundary with respect to the contact surface of the support portion 271 (here, the inner peripheral surface of the through hole 271c) 271c ′. It is configured to be located at a position displaced toward the end portion 273b ″ (here, at a position corresponding to the outside of the inner peripheral surface of the through hole 271c and inside the boundary end portion 273b ″).

  In the present embodiment, the elastic member 274 includes a first member 275 fixed to the fixing device main body, and a second member 276 that is supported by the first member 275 and supports the claw 273. . Note that either one of the first member 275 and the second member 276 may be an elastic member.

  Specifically, the first member 275 has a base end portion 275a fixed to the fixing device main body, and extends in a tangential direction from the base end portion 275a to the front end portion 275b at the contact position of the heating roller 123 with the temperature sensor 130. It extends substantially in parallel. The second member 276 has a proximal end portion 276a connected to the distal end portion 275b of the first member 275, and is supported from the proximal end portion 276a to the distal end portion 276b in the state shown in FIGS. 2 and 3A. It extends in a direction substantially orthogonal to the support portion 271 so as to face the portion 271, and the tip end portion 276 b is a free end portion. A claw 273 is provided at the distal end portion 276b.

  In the fixing unit 27 described above, in the case of an unused product, the temperature sensor 130 is positioned at the initial position (see FIGS. 2 and 3A) by the support portion 271. When the heating roller 123 is heated by the fixing heaters 128 and 129, as shown in FIG. 3B, the support portion 271 is deformed as the temperature of the heating roller 123 rises, and the temperature sensor 130 is moved from the initial position to the contact position. It moves to a position (refer FIG.3 (c)).

  At this time, since the retracting portion 273b of the claw 273 of the latch portion 272 is an inclined surface that is inclined to retract the fixed portion 273a to the retracted position, the contact surface of the support portion 271 (here, the through hole 271c). Of the elastic member 274 against the elastic force of the elastic member 274 and retracts the fixing portion 273a to the retracted position to allow the temperature sensor 130 to move to the contact position. As shown in FIG. 3C, when the temperature sensor 130 is positioned at the contact position, the retracting operation to the retracted position by the retracting portion 273b is released, and the fixing portion 273a is moved by the elastic force of the elastic member 274. The temperature sensor 130 is moved from the retracted position to the fixing direction to fix the temperature sensor 130 at the contact position, and the elastic member 274 cooperates with the fixing portion 273a to press the temperature sensor 130 toward the heating roller 123.

  In the fixing unit 27 having such a configuration, in the case of an unused product, the temperature sensor 130 measures the temperature while the support portion 271 moves from the initial position toward the contact position, and then heats at the contact position. The surface temperature of the roller 123 is measured. On the other hand, in the case of a used product, the temperature sensor 130 measures the surface temperature of the heating roller 123 at the contact position from the beginning. Thereby, the measurement temperature characteristic in the measurement initial stage (the heating initial stage to the heating roller 123) of the temperature sensor 130 can be made different between the unused product and the used product.

  In the present embodiment, a cover 277 that shields the latch portion 272 and the support portion 271 from the outside is provided. A latch portion 272 and a support portion 271 are fixed to the cover 277. Therefore, the temperature sensor 130 is fixed to the cover 277 via the support portion 271.

  The cover 277 touches the temperature sensor 130, the support portion 271, and the latch portion 272 inadvertently (for example, a user) such as an exchange operator who has replaced the used fixing unit 27, and touches the temperature sensor 130 and the support member 271. Is provided so as not to return it to the unused posture.

[Entire configuration of image forming apparatus]
Next, the overall configuration of the image forming apparatus 100 equipped with the fixing unit 27 will be described. FIG. 4 is a side view schematically showing the configuration of the image forming apparatus 100 according to an embodiment of the present invention. In FIG. 4, the temperature sensor 130 and the cleaning unit 131 in the fixing unit 27 are not shown.

  An image forming apparatus 100 shown in FIG. 4 forms an image by an electrophotographic image forming process. The image forming apparatus 100 charges a latent image carrier (here, a photosensitive drum) 21 and the surface of the photosensitive drum 21. A charging device 22, an exposure device (here, an optical writing unit) 23 for forming an electrostatic latent image on the photosensitive drum 21, and developing the electrostatic latent image with a developer to form the electrostatic latent image on the photosensitive drum 21. A developing device 24 for forming a toner image, a transfer device (here, a transfer unit) 25 for transferring the toner image on the photosensitive drum 21 to the recording material P, and a transfer image on the recording material P are recorded on the recording material P A fixing device (here, a fixing unit) 27 for fixing to the material P, and a cleaning device (here) for removing residual toner that is not transferred by the transfer device 25 and remains on the surface of the photosensitive drum 21 Includes a cleaning unit) 26, charge removing device for neutralizing the remaining residual charge on the surface of the photosensitive drum 21 and a (not shown).

  Specifically, the image forming apparatus 100 acquires image data read from a document, or acquires image data received from the outside, and forms a monochrome image indicated by the image data on the recording material P. The configuration is roughly divided into a document conveying unit (ADF) 101, an image reading unit 102, an image forming unit 103, a recording material conveying unit 104, and a paper feeding unit 105.

  When at least one document is set on the document setting tray 11, the document conveying unit 101 pulls out the document one by one from the document setting tray 11, conveys the document to the image reading unit 102, and passes the document. The original is discharged to the paper discharge tray 12.

  The image reading unit 102 reads a document image from the document conveying unit 101 and transmits image data corresponding to the document image to a control unit 200 including a microcomputer.

  The image data transmitted from the image reading unit 102 to the control unit 200 is subjected to various image processing by the control unit 200 and then output to the image forming unit 103.

  The image forming unit 103 records a document image based on the image data on the recording material P, and includes the above-described photosensitive drum 21, charging device 22, exposure device 23, developing device 24, transfer device 25, cleaning device. A device 26, a fixing device 27, and a static eliminator are provided.

  The surface of the photosensitive drum 21 moves in a predetermined direction (rotates in the direction of arrow A in the figure), the surface is cleaned by the cleaning device 26, and the cleaned surface is uniformly charged by the charging device 22.

  In the present embodiment, the charging device 22 is a scorotron charger having a grid electrode. Specifically, the charging device 22 is of a charger type, and a grid electrode is provided between the corona wire and the photoconductor 21.

  The optical writing unit 23 acting as an exposure apparatus is a laser scanning unit (LSU) including a laser irradiation unit 28 that is a laser light source and a mirror group 29. The optical writing unit 23 receives image data from the control unit 200, emits laser light corresponding to the image data from the laser irradiation unit 28, and outputs the laser light via the mirror group 29 to the photosensitive drum. 21, the surface of the photosensitive drum 21 that is uniformly charged is exposed, and an electrostatic latent image is formed on the surface of the photosensitive drum 21.

  The developing device 24 supplies toner to the surface of the photosensitive drum 21 to visualize (develop) the electrostatic latent image formed on the photosensitive drum 21.

  The transfer unit 25 transfers the toner image formed on the surface of the photosensitive drum 21 onto the recording material P conveyed by the recording material conveyance unit 104.

  Specifically, the transfer unit 25 has an elastic conductive roller 34. The elastic conductive roller 34 presses the recording material P conveyed from the recording material conveyance unit 104 against the surface of the photosensitive drum 21. Further, an electric field having a polarity opposite to the charge of the toner image on the surface of the photosensitive drum 21 is applied to the elastic conductive roller 34, and the toner image on the surface of the photosensitive drum 21 is applied to the recording material P by the electric field having the opposite polarity. Transcribed. For example, when the toner image has a (−) polarity charge, the polarity of the electric field applied to the elastic conductive roller 34 is set to the (+) polarity.

  The cleaning unit 26 removes and collects toner remaining on the surface of the photosensitive drum 21 after development and transfer.

  The fixing unit 27 is as described above, and a description thereof is omitted here.

  The recording material conveyance unit 104 includes a plurality of pairs of conveyance rollers 41, a pair of registration rollers 42, and a conveyance path 43 for conveying the recording material P from the paper supply unit 105.

  The paper feed unit 105 includes a plurality of paper feed trays 51. Each paper feed tray 51 is for storing the recording material P, and is provided below the image forming apparatus 100. Each paper feed tray 51 is provided with a pickup roller for pulling out the recording material P one by one, and the recording material P pulled out by the pickup roller is sent out to the transport path 43 of the recording material transport unit 104. It has become.

  The conveyance path 43 conveys the recording material P, which has received the recording material P from the paper feeding unit 105, to the transfer unit 25 by the registration roller 42 in synchronization with the toner image on the rotating photosensitive member 21. It is conveyed to the fixing unit 27. The recording material P fixed by the fixing unit 27 is further transported to the paper discharge tray 47 by the recording material transport unit 104 and discharged.

  The image forming apparatus 100 includes an operation unit such as an operation panel (not shown), and a display unit 240 (see FIG. 5) described later is provided in the operation unit.

[Description of Features of Image Forming Apparatus According to the Present Invention]
FIG. 5 is a schematic block diagram of a control system mainly showing the control unit 200 provided in the image forming apparatus 100 shown in FIG.

  The control unit 200 includes an information processing apparatus such as a CPU (Central Processing Unit), and controls the entire image forming apparatus 100 by executing various control programs (for example, measurement of the temperature sensor 130 as described above). It is configured to perform surface temperature control of the heating roller 123 based on the output and detection of measured temperature characteristics of a temperature sensor 130 described later).

  As shown in FIG. 5, the control unit 200 connects a temperature sensor 130, a memory 210, and a fixing heater driver 220.

  The temperature sensor 130 can transmit a measurement output signal to the control unit 200. The memory 210 is, for example, a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a ROM (Read Only Memory), an rewritable nonvolatile memory such as an EEPROM (Erasable Programmable ROM), a flash memory, or a hard disk. The above-mentioned various control programs, necessary functions, and data processed by the control unit 200 are stored (for example, a counter indicating the usage time or the number of printed sheets of the fixing unit 27 is stored in a rewritable nonvolatile memory. ). The fixing heater driver 220 performs energization control to the fixing heaters 128, 129, and 138 under the instruction of the control unit 200.

  The control unit 200 is further connected to a timer 230 that measures the measurement time of the temperature sensor 130. The timer 230 can transmit the measurement time from the time of reset to the control unit 200.

  In addition, the control unit 200 is further connected to a display unit 240 that displays information such as the image forming state of the image forming apparatus 100 and operation guidance. In the present embodiment, the display unit 240 displays a message notifying the user that a member requiring replacement such as the fixing unit 27 has come to be replaced due to the end of its life, and displays various errors. ing.

  The control unit 200 is configured to detect the measured temperature characteristic of the temperature sensor 30 based on the measurement output of the temperature sensor 130 and determine whether the fixing unit 27 is an unused product based on the detected measured temperature characteristic. Has been.

  According to the image forming apparatus 100 having such a configuration, since the fixing unit 27 according to the above-described embodiment of the present invention is mounted, an unused product and a used product of the fixing unit 27 are supplied to the heating roller 123. The measured temperature characteristics of the temperature sensor 130 at the initial stage of heating (initial stage of measurement) can be made different, and the fixing unit 27 is not used based on the measured temperature characteristics detected by the temperature sensor 130 by utilizing the difference in measured temperature characteristics. It is possible to detect whether the product is used.

  In the present embodiment, the control unit 200 has a gradient of the measurement output value of the temperature sensor 130 (the amount of change in the surface temperature of the heating roller 123 per unit time, hereinafter referred to as a temperature gradient) equal to or greater than a predetermined value R (see FIG. 6). When it is detected, the fixing unit 27 is determined to be an unused product.

  FIG. 6 is a graph of measured temperature characteristics showing the relationship between the temperature measured by the temperature sensor 130 and the elapsed measurement time. In FIG. 6, the solid line indicates the measured temperature characteristic when the fixing unit 27 is an unused product, and the broken line indicates the measured temperature characteristic when the fixing unit 27 is a used product. The symbol TH0 is an upper limit value of the surface temperature of the heating roller 123. For example, the temperature TH0 is set to a temperature at which the resin of the surface elastic layer 123b of the heating roller 123 is not melted and destroyed by heat (specifically, 200 ° C.). it can.

  In the used fixing unit 27, as shown in FIG. 3C, the temperature sensor 130 is positioned at the contact position in the initial stage of heating (measurement initial stage) of the heating roller 123. Since the temperature is measured in a state where there is almost no temperature difference from the sensor 130, the temperature gradient changes within a predetermined gradient range (see β in the figure) smaller than the predetermined value R. On the other hand, in the unused fixing unit 27, as shown in FIG. 2 and FIG. 3A, the temperature sensor 130 is located at the initial position at the initial stage of heating the heating roller 123 (initial stage of measurement). Since the ambient temperature is measured before moving from the initial position to the contact position, and the surface temperature of the heating roller 123 is measured after being positioned at the contact position, the temperature sensor 130 is positioned from the initial position to the contact position. Until the temperature gradient is smaller than the gradient range β (see δ in the figure), and after the temperature sensor 130 is positioned at the contact position, the temperature difference between the surface of the heating roller 123 and the temperature sensor 130 has been used. Since the temperature is measured in a larger state than the case of the fixing unit 27 of the product, the temperature changes at a predetermined value R or more (slope that is steeper than the slope range β, see γ in the figure).

  From this point of view, when the control unit 200 detects that the temperature gradient is greater than or equal to a predetermined value R within a predetermined time (here, a predetermined time after the time when the fixing heaters 128 and 129 are turned on) T1, the fixing unit 27 is detected. Is determined to be an unused product, and when it is detected that the temperature gradient is within the gradient range β within a predetermined time T1, the fixing unit 27 is determined to be a used product. . Note that the predetermined time T1 is a use state in which the surface temperature of the heating roller 123 to be heated is normally assumed (for example, the surface temperature of the heating roller 123 when the heating roller 123 is heated is room temperature (specifically, 35 ° C. The following time) can be set to a time that does not exceed the upper limit value TH0 of the surface temperature of the heating roller 123.

  In the present embodiment, the control unit 200 further determines that the temperature gradient is equal to or greater than a predetermined value R even when a predetermined time (here, a predetermined time after the time when the fixing heaters 128 and 129 are turned on) T1 is exceeded (here, a gradient range). The fixing unit 27 is determined to be in failure when the value is not equal to or higher than the lower limit value of β.

  In the present embodiment, the control unit 200 further issues an alarm when determining that the fixing unit 27 is out of order (here, a message notifying the user that the fixing unit 27 is out of order on the display unit 240). Display).

  Next, a processing flow for detecting the measured temperature characteristic of the temperature sensor 130 and determining whether or not the fixing unit 27 is an unused product will be described. FIG. 7 is a flowchart showing the flow of processing for detecting the measured temperature characteristic of the temperature sensor 130 and determining whether or not the fixing unit 27 is an unused product.

  In this process, when the image forming apparatus 100 is turned on or when opening / closing of a cover (not shown) such as a main body door covering the fixing unit 27 is detected, the fixing unit 27 may be replaced. At this time, the processing flow shown in FIG. 7 is started.

  In the processing flow shown in FIG. 7, first, the fixing heaters 128 and 129 are turned on (step S100), and the measurement time by the temperature sensor 130 of the timer 230 is reset (step S110). The timer 230 may be reset before the fixing heaters 128 and 129 are turned on.

  Next, within the predetermined time T1 when the output value of the timer 230 is measured from the reset time (step S120: No), the temperature gradient (for example, the sensor detected temperature by the temperature sensor 130 and a certain minute time before the detection time). Is determined whether the temperature gradient is within the gradient range β (step S130: Yes). If the temperature gradient is within the gradient range β (step S130: Yes), the fixing is performed. It is determined that the unit 27 is a used product (step S140), and the process ends.

  On the other hand, if it is determined in step S130 that the temperature gradient is not within the gradient range β (step S130: No), it is determined whether or not the temperature gradient is equal to or greater than a predetermined value R (step S150). Is not greater than or equal to the predetermined value R (step S150: No), unless the sensor detected temperature by the temperature sensor 130 exceeds the upper limit value TH0 of the surface temperature of the heating roller 123 (step S160: No), step S120 -The process of step S160 is performed. At this time, if the sensor detected temperature exceeds the upper limit value TH0 (step S160: Yes), a message indicating that the fixing unit 27 has failed is displayed on the display unit 240 (step S190), and the heater is turned off (step S190). Step S200) and the process ends.

  On the other hand, if it is determined in step S150 that the temperature gradient is equal to or greater than the predetermined value R (step S150: Yes), the fixing unit 27 is determined to be unused (step S170) and stored in the memory 210. The counter indicating the usage time or the number of printed sheets of the fixing unit 27 is cleared (step S180), and the process is terminated.

  If it is determined in step S120 that the output value of the timer 230 has exceeded the predetermined time T1 (step S120: Yes), a message indicating that the fixing unit 27 has failed is displayed on the display unit 240 (step S190), and the heater is heated. Is turned off (step S200), the process is terminated.

  In the present embodiment, the configuration of the present invention is applied to the heating roller 123, but may be applied to the pressure roller 124.

FIG. 2 is a side view schematically showing a configuration of a fixing unit which is an example of a fixing device according to the present invention. It is explanatory drawing which expands and shows the temperature sensor shown in FIG. 1, a support part, and a latch part part, Comprising: It is a figure which shows the state in which the temperature sensor is located in the initial position. FIG. 2 is a state transition diagram of the temperature sensor, the support portion, and the latch portion shown in FIG. 2, in which FIG. (A) is a diagram showing a state where the temperature sensor is located at an initial position, and FIG. It is a figure which shows the state which a temperature sensor transfers to a measurement position from an initial position, and FIG.5 (c) is a figure which shows the state in which the temperature sensor is located in a measurement position. 1 is a side view schematically showing a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 5 is a schematic block diagram of a control system mainly showing a control unit provided in the image forming apparatus shown in FIG. 4. It is a graph of the measurement temperature characteristic which shows the relationship between the measurement temperature by a temperature sensor, and measurement elapsed time. 6 is a flowchart showing a flow of processing for detecting whether or not a fixing unit is an unused product by detecting a measured temperature characteristic of a temperature sensor.

Explanation of symbols

27 Fixing unit (an example of a fixing device)
100 Image forming apparatus 123 Heating roller (an example of a fixing roller)
130 Temperature sensor 200 Control unit 271 Support unit 272 Latch unit 273 Claw 273a Fixing unit 273b Retraction unit 274 Elastic member 277 Cover R Predetermined value T1 Predetermined time

Claims (8)

In the fixing device provided in the image forming apparatus,
A heated fixing roller;
A temperature sensor for measuring the surface temperature of the fixing roller,
The measurement temperature characteristic of the temperature sensor at the initial stage of heating to the fixing roller is configured to be different between an unused product and a used product of the fixing device ,
The temperature sensor is supported at an initial position separated from the fixing roller, and is deformed as the temperature of the fixing roller rises and moves from the initial position toward a measurement position for measuring the surface temperature of the fixing roller. A support part to be
A latch portion for fixing the temperature sensor so as to maintain the temperature sensor at the measurement position when the temperature sensor moves to the measurement position at the support portion;
Fixing device characterized in that it comprises a. The fixing device according to claim 1 .
The latch portion includes a claw for fixing the temperature sensor, and an elastic member that supports the claw,
The claw includes a fixing unit that fixes the temperature sensor at the measurement position so as to prevent return deformation of the support unit due to a temperature drop, and an initial position of the temperature sensor that accompanies deformation due to a temperature rise of the support unit. A fixing device, comprising: a retracting portion that retracts the fixing portion against an elastic force of the elastic member during movement to the measurement position and allows the temperature sensor to move to the measurement position. In the fixing device according to claim 1 or 2 ,
The fixing device is formed of a shape memory alloy or a bimetal. The fixing device according to any one of claims 1 to 3,
A fixing device comprising a cover for shielding the latch portion and the support portion from the outside. A fixing device according to any one of claims 1 to 4 ,
A control unit for detecting a measured temperature characteristic of the temperature sensor based on a measurement output of the temperature sensor,
The image forming apparatus, wherein the control unit determines whether the fixing device is an unused product based on a measured temperature characteristic detected by the temperature sensor. The image forming apparatus according to claim 5 .
The image forming apparatus, wherein the controller determines whether the fixing device is an unused product based on a gradient of a measurement output value of the temperature sensor. The image forming apparatus according to claim 6 .
The control unit determines that the fixing device is an unused product when detecting that the gradient of the measured output value of the temperature sensor is equal to or greater than the predetermined value within a predetermined time. apparatus. The image forming apparatus according to claim 6 or 7 ,
The image forming apparatus according to claim 1, wherein the control unit determines that the fixing device is out of order when a gradient of a measured output value of the temperature sensor does not exceed the predetermined value even after a predetermined time has elapsed.

Images