JP5769072B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer using electrophotographic technology, and a fixing device used in such an image forming apparatus.

  In general, an electrophotographic image forming apparatus employs a thermal fixing method in which heat is applied to a toner image transferred onto a sheet as a transfer material to fix the toner image. As shown in FIGS. 16 and 17, the fixing device used for this thermal fixing includes a fixing roller 121 as a fixing member and a pressure roller 122 as a pressure member.

  The fixing roller 121 includes, for example, a cylindrical roller main body 125 including a heat conductive base 123 and an exterior body 124 that covers the base 123, and a heating source 126 such as a halogen heater provided in the roller main body 125. Is provided. The exterior body 124 includes an elastic layer and a surface layer that covers the elastic layer. The pressure roller 122 includes a cored bar 127 and an exterior body 128 that covers the cored bar 127. The exterior body 128 includes an elastic layer and a surface layer that covers the elastic layer.

  The fixing roller 121 and the pressure roller 122 are pressed by a spring member (not shown) so as to be in pressure contact with each other, and a fixing nip N is formed. By the way, with respect to such a fixing device, there are cases where the transfer material P is plain paper or an envelope. However, the envelope folds and bonds the paper. For this reason, when such an envelope passes through the fixing nip, distortion and wrinkles may occur.

  Therefore, conventionally, when the plain paper is passed, the fixing nip N is wide as shown in FIG. 16, and when the envelope is passed, the fixing roller 121 and the pressure roller 122 are shown as shown in FIG. The pressure contact pressure (fixing pressure) was reduced. In this way, the range of the fixing nip N is reduced so that wrinkles and the like are hardly generated even when the envelope is passed. Some conventional image forming apparatuses use a cam mechanism as a method for increasing the distance between the fixing roller 101 and the pressure roller 122 (Patent Documents 1 to 3).

  In Patent Document 1, a pressure roller is supported by a lever, and an arm having an intermediate portion pivoted is disposed near the lever. A spring member is disposed between one end of the arm and the base end of the lever, and a cam mechanism is connected to the other end of the arm.

  That is, by rotating the cam of the cam mechanism, the other end of the arm is moved up and down, thereby adjusting the push-up amount of the machine end of the lever pushed up via the spring member. The nip length is adjusted by adjusting the push-up amount.

  Patent Document 2 also has a pressure changing mechanism that changes the pressure applied to the nip portion, and includes a cam member that acts on the pressure applying mechanism as the pressure changing mechanism.

  Also in Patent Document 3, the pressure applied by the pressure roller is adjusted by rotating the cam. In this case, a sensor for detecting the position of the cam is provided. That is, by detecting the position of the cam, the user grasps the pressure state of the pressure roller.

  In the ones described in Patent Document 1 and Patent Document 2, the pressure applied to the nip portion can be changed, but it cannot be detected whether the nip pressure is a predetermined pressure. In addition, the device described in Patent Document 1 requires its space, a motor (step motor), a worm, a worm wheel, and the like in order to rotate the cam. For this reason, the whole apparatus becomes complicated, large, and high in cost. In Patent Document 2, the power transmission to the cam uses the rotation shaft of the transport roller. For this reason, the change of the pressure applied to the nip is interlocked with the rotation of the rotation shaft of the transport roller, and the pressure cannot be adjusted independently of the transport roller, resulting in poor controllability.

  On the other hand, in Patent Document 3, it is possible to detect the normal pressurization mode or the reduction mode. However, even the device described in Patent Document 3 requires a space and a drive source for rotating the cam, which leads to complication, enlargement, and cost increase of the entire apparatus.

  SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide a fixing device and an image forming apparatus capable of stably controlling the nip pressure on a roller pair with a simple configuration at low cost.

The fixing device according to the present invention adjusts the nip pressure by operating a roller pair in which a pair of rollers are arranged in parallel to form a nip and a pair of operation levers disposed on both ends of the roller pair in the axial direction. The adjusting device includes a first operating body that performs a first operation that is a linear operation in conjunction with the first operating lever, and a second operating lever that is interlocked with the first operating lever. And a second operation body that performs the second operation that is a rotation operation, and one detection means that detects that both the first operation and the second operation have been performed. .

  According to the fixing device of the present invention, the nip pressure can be adjusted by operating a pair of operation levers disposed on both ends of the roller pair in the axial direction. For this reason, a uniform pressure can be applied in the entire axial length. In addition, the detection means can detect that both the first operation and the second operation are performed, and whether both the first lever and the second lever (both) are operated. You can determine if you are not operating. That is, the dynamic state of the roller pair can be detected. In addition, since only one detecting means is required, downsizing can be achieved.

  The image forming apparatus of the present invention includes the fixing device. According to the image forming apparatus of the present invention, in the fixing device, the nip pressure can be adjusted by operating a pair of operation levers disposed on both ends in the axial direction of the roller pair. For this reason, a uniform pressure can be applied in the entire axial length. In addition, the detection means can detect that both the first operation and the second operation are performed, and whether both the first lever and the second lever (both) are operated. You can determine if you are not operating. That is, the dynamic state of the roller pair can be detected. In addition, since only one detecting means is required, downsizing can be achieved.

  In the fixing device of the present invention, by operating both operation levers, the nip pressure can be applied uniformly over the entire length in the axial direction, and a stable fixing function can be exhibited. In addition, since any one of the operating levers is not operated and the dynamic state of the roller pair is not detected, the fixing operation is performed assuming that the nip pressure is changed without any of the operating levers being operated. Can be prevented. That is, it is possible to provide a fixing device capable of stably controlling (changing) the nip pressure on the roller pair at a low cost with a simple configuration. In addition, since only one detecting means is required, downsizing can be achieved.

  In the image forming apparatus of the present invention, the fixing device that exhibits the above-described effects is provided, and the nip pressure can be stably controlled (changed) on the roller pair with a simple configuration at low cost. An image forming apparatus can be provided.

1 shows a fixing device according to a first embodiment, wherein (a) is a simplified plan view in a high-pressure contact state, and (a) is a simplified plan view in a low-pressure contact state. 1 shows the fixing device of FIG. 1, wherein (a) is a simplified front view in a high pressure contact state, and (a) is a simplified front view in a low pressure contact state. FIG. 2 is an overall configuration diagram of an image forming apparatus using the fixing device shown in FIG. 1. The fixing roller and the pressure roller are shown, (a) is a sectional view in a high pressure contact state, and (b) is a sectional view in a low pressure contact state. The fixing device which concerns on 2nd Embodiment is shown, (a) is a simplified top view of a high voltage | pressure contact state, (a) is a simplified plan view of a low voltage | pressure contact state. 5 shows the fixing device of FIG. 5, wherein (a) is a simplified front view in a high pressure contact state, and (a) is a simplified front view in a low pressure contact state. FIG. The fixing device which concerns on 3rd Embodiment is shown, (a) is a simplified top view of a high voltage | pressure contact state, (a) is a simplified top view of a low voltage | pressure contact state. 7 shows the fixing device of FIG. 7, wherein (a) is a simplified front view in a high pressure contact state, and (a) is a simplified front view in a low pressure contact state. The fixing device which concerns on 4th Embodiment is shown, (a) is a simplified top view of a high voltage | pressure contact state, (a) is a simplified plan view of a low voltage | pressure contact state. FIG. 7 shows a fixing device according to a fifth embodiment, wherein (a) is a simplified plan view in a high-pressure contact state, and (a) is a simplified plan view in a low-pressure contact state. FIG. 9 shows a fixing device according to a sixth embodiment, wherein (a) is a simplified plan view in a high-pressure contact state, and (a) is a simplified plan view in a low-pressure contact state. It is a principal part simplification figure of the fixing device using a contact-type sensor as a detection means. 12 shows the contact type sensor shown in FIG. 12, wherein (a) is a simplified diagram of a detection state, and (b) is a simplified diagram of a non-detection state. It is a principal part simplification figure of the fixing device using another non-contact-type sensor as a detection means. FIG. 14 shows the non-contact sensor shown in FIG. 14, where (a) is a simplified diagram of the detection state, and (b) is a simplified diagram of the non-detection state. FIG. 2 is a simplified diagram showing a conventional fixing device in a high-pressure contact state. FIG. 9 is a simplified diagram showing a conventional fixing device in a low-pressure contact state.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention according to embodiments shown in the drawings will be described.

  FIG. 3 is a schematic configuration diagram illustrating an embodiment of the image forming apparatus. The image forming apparatus shown in FIG. 3 includes four process units 1Y, 1C, 1M, and 1BK. Each process unit 1Y, 1C, 1M, 1BK is configured to be detachable from the image forming apparatus main body 100.

  The process units 1Y, 1C, 1M, and 1BK have the same configuration except that they contain toners of different colors of yellow, cyan, magenta, and black corresponding to the color separation components of the color image. Therefore, the configuration of one process unit 1Y will be described as an example.

  The process unit 1Y includes a photosensitive member 2 as an image carrier, a charging roller 3 as a charging unit that charges the surface of the photosensitive member 2, and a developing device 4 as a developing unit that forms a toner image on the surface of the photosensitive member 2. And a photosensitive member cleaning blade 5 as a cleaning means for cleaning the surface of the photosensitive member 2.

  Above each of the process units 1Y, 1C, 1M, and 1BK, an exposure device 7 is disposed as an exposure unit that exposes the surface of the photoreceptor 2. An intermediate transfer unit 6 is disposed below each process unit 1Y, 1C, 1M, 1BK. The intermediate transfer unit 6 has an intermediate transfer belt 10 constituted by an endless belt. The intermediate transfer belt 10 is stretched around a driving roller 8 and a driven roller 9 and is configured to be able to run around in the direction of the arrow in the figure.

  On the inner peripheral surface of the intermediate transfer belt 10, four primary transfer rollers 11Y, 11C, 11M, and 11BK are disposed as primary transfer means. Each of the primary transfer rollers 11Y, 11C, 11M, and 11BK is in pressure contact with the inner peripheral surface of the intermediate transfer belt 10 at a position facing the photoreceptor 2, and each photoreceptor 2 is in contact with the intermediate transfer belt 10 by this pressure contact. A primary transfer nip is formed in pressure contact with the outer peripheral surface.

  A secondary transfer roller 12 as a secondary transfer unit is disposed at a position facing the driving roller 8 that stretches the intermediate transfer belt 10. The secondary transfer roller 12 is in pressure contact with the outer peripheral surface of the intermediate transfer belt 10 and forms a secondary transfer nip at the pressure contact portion.

  The intermediate transfer unit 6 includes a belt cleaning device 21 for cleaning the surface of the intermediate transfer belt 10. A waste toner container 22 for storing waste toner is disposed below the intermediate transfer unit 6. A waste toner transfer hose (not shown) extending from the belt cleaning device 21 is connected to the entrance of the waste toner container 22.

  Under the image forming apparatus main body 100, a recording medium accommodating portion 13 that accommodates a recording medium P such as paper or an OHP sheet is disposed. The recording medium accommodating portion 13 is provided with a supply roller 14 for carrying out the recording medium P and the like.

  In the image forming apparatus main body 100, a conveyance path R <b> 1 for guiding the recording medium P upward from the recording medium container 13 is disposed. A pair of registration rollers 15a and 15b are disposed upstream of the secondary transfer nip formed by the drive roller 8 and the secondary transfer roller 12 in the transport direction of the transport path R1 (downward in the drawing). Further, the fixing device 16 is disposed downstream of the secondary transfer nip in the transport direction of the transport path R1 (upward in the drawing). The fixing device 16 includes a fixing roller 17 and a pressure roller 18. The fixing roller 17 and the pressure roller 18 are in pressure contact with each other, and a fixing nip is formed at the pressure contact portion.

  A pair of discharge rollers 19a and 19b are disposed at the downstream end of the transport path R1 in the transport direction. In addition, a stock unit 20 on which the recording medium P is loaded is formed by denting the upper surface of the image forming apparatus main body 100 inward.

The basic operation of the image forming apparatus will be described below with reference to FIG.
In the process unit 1Y, the photosensitive member 2 is rotated in the direction of the arrow in the figure, and the surface of the photosensitive member 2 is charged to a uniform high potential by the charging roller 3. Next, a laser beam is irradiated from the exposure device 7 to the surface of the photoconductor 2 based on the image data, and the potential of the irradiated portion is lowered to form an electrostatic latent image. The toner charged by the developing device 4 is electrostatically transferred to the portion of the electrostatic latent image formed on the surface of the photoreceptor 2 to form a yellow toner image (visualization).

  The primary transfer roller 11Y is applied with a constant voltage or a constant current controlled voltage having a polarity opposite to the charging polarity of the toner. As a result, a transfer electric field is formed in the primary transfer nip between the primary transfer roller 11Y and the photoreceptor 2. Then, in the primary transfer nip, the toner image on the rotating photoconductor 2 is primarily transferred to the intermediate transfer belt 10 running in the direction of the arrow in the figure.

  In each of the other process units 1C, 1M, and 1BK, similarly, a toner image is formed on the photoreceptor 2, and the four color toner images are primarily transferred to the intermediate transfer belt 10 so as to overlap each other.

  Further, the surface of the photoreceptor 2 after the primary transfer process is cleaned by the photoreceptor cleaning blade 5 to remove residual toner. Further, the residual charge remaining on the surface of the photoreceptor 2 is neutralized by a neutralizing lamp (not shown).

  On the other hand, the recording medium P stored in the recording medium storage unit 13 is sent out to the transport path R1 by rotating the supply roller 14. The sent recording medium P is temporarily stopped by the registration rollers 15a and 15b.

  Further, a voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 12 to form a transfer electric field in the secondary transfer nip. Alternatively, a similar transfer electric field may be formed by applying a voltage having the same polarity as the charging polarity of the toner to the driving roller 8 facing the secondary transfer roller 12. Thereafter, the driving of the registration rollers 15a and 15b is resumed, and the recording medium P is sent to the secondary transfer nip in synchronism with the toner image on the intermediate transfer belt 10. Then, the toner image on the intermediate transfer belt 10 is secondarily transferred collectively onto the recording medium P by the transfer electric field formed in the secondary transfer nip. Further, after the secondary transfer, the toner remaining on the surface of the intermediate transfer belt 10 is removed by the belt cleaning device 21, and the removed toner is collected in the waste toner container 22.

  The recording medium P to which the toner image has been transferred is conveyed to the fixing device 16. The recording medium P sent to the fixing device 16 is sandwiched between the fixing roller 17 and the pressure roller 18 and heated and pressurized, and the toner image is fixed on the recording medium P. Thereafter, the recording medium P is discharged to the stock unit 20 by the discharge rollers 19a and 19b.

  As shown in FIGS. 1 and 2, the fixing device 16 is attached in a direction in which the fixing roller 17 as a fixing member, the pressure roller 18 as a pressure member, and the fixing roller 17 and the pressure roller 18 are in pressure contact with each other. And elastic members 31, 31 for energizing. The fixing roller 17 and the pressure roller 18 constitute a roller pair 30.

  As shown in FIG. 4, the fixing roller 17 includes, for example, a cylindrical roller body 25 including a heat conductive base 23 and an exterior body 24 covering the base 23, and a halogen incorporated in the roller body 25. And a heating source 26 such as a heater. The exterior body 24 includes an elastic layer and a surface layer that covers the elastic layer.

  The thermally conductive base 23 is made of a carbon steel material, an aluminum material or the like having a required mechanical strength and good thermal conductivity. The elastic layer of the exterior body 24 is made of synthetic rubber such as silicone rubber or fluorine rubber, for example. As the surface layer, a material that has good releasability from the toner and enhances the durability of the elastic layer and has high thermal conductivity and high durability is used. It is composed of a fluororesin (PFA) tube, a fluororesin (PFA) coating layer, a coating layer of silicone rubber, fluororubber, or the like.

  The fixing roller 17 has an outer diameter of about 15 mm to 40 mm, a thickness of the elastic layer of the exterior body 24 is about 0.5 mm to 3 mm, and a thickness of the surface layer of the exterior body 24 is about 10 μm to 80 μm. Is done. In this example, the outer diameter was 24 mm, the thickness of the elastic layer was 1 mm, and the thickness of the surface layer was 43 μm.

  The pressure roller 18 includes a cored bar 27 and an exterior body 28 that covers the cored bar 27. The exterior body 28 includes an elastic layer and a surface layer that covers the elastic layer. The core metal 27 is made of, for example, STKM (carbon steel pipe for mechanical structure) or the like, and the elastic layer of the exterior body 28 is made of silicone rubber, fluorine rubber, or the like, or a foam thereof. The surface layer of the outer package 28 is composed of a tube of heat-resistant fluororesin such as PFA or PTFA, which is rich in releasability.

  The pressure roller 18 has an outer diameter of about 20 mm to 40 mm, a thickness of the elastic layer of the exterior body 28 is about 0.5 mm to 10 mm, and a thickness of the surface layer of the exterior body 28 is about 10 μm to 80 μm. It is said. In this example, the outer diameter was 30 mm, the thickness of the elastic layer was 8 mm, and the thickness of the surface layer was 50 μm.

  In the vicinity of the fixing roller 17, a thermistor (not shown) as temperature detecting means, a thermistor for preventing abnormal temperature (not shown), and the like are arranged, and detection signals from these thermistors are sent to control means (not shown). Entered. Then, for example, the temperature of the fixing roller 17 is maintained within a predetermined temperature range by a control unit configured by a microcomputer or the like. A fixing inlet guide (not shown) is provided upstream of the fixing nip N in the recording medium conveyance direction, and a fixing outlet guide (not shown) is provided downstream of the fixing nip N in the recording medium conveyance direction.

  By the way, as shown in FIG. 1 and FIG. 2, the pressure roller 18 includes shaft members 42a and 42b supported by a pair of holder members 41a and 41b disposed on the axial end side. The elastic members 31a and 31b are attached to 41b. That is, the elastic members 31a and 31b are interposed between the holder members 41a and 41b and the base members 43a and 43b, respectively.

  For this reason, the pressure roller 18 is pressed against the fixing roller 17 by the elastic force of the elastic members 31a and 31b, thereby forming a nip N as shown in FIGS. The apparatus includes an adjusting unit 50 that adjusts the nip pressure by an operation using a pair of operation levers 45a and 45b disposed on both ends of the roller pair 30 in the axial direction.

  As shown in FIG. 1, the adjusting means 50 performs a first operation body 51 that performs a first operation in conjunction with the first operation lever 45a, and a second operation in conjunction with the second operation lever 45b. A second operating body 52 to be performed and one detecting means 53 for detecting that both the first operation and the second operation have been performed are provided.

  The operation levers 45a and 45b rotate around the fulcrums 55a and 55b. In the state shown in FIG. 4A, that is, in the state rotated in the direction of the arrow A1, the engaging portions 56a and 45b of the operation levers 45a and 45b are provided. The base members 43a and 43b engaged with 56b are pressed toward the roller pair 30 side. By this pressing, the fixing roller 17 and the pressure roller 18 are in a high-pressure contact state, that is, a state where the nip N width is large.

  On the other hand, from the state shown in FIG. 4A, the operation levers 45a and 45b are rotated in the direction of the arrow A2 around the fulcrums 55a and 55b, as shown in FIG. The base members 43a and 43b are pulled toward the opposite side of the roller against the elastic force of the elastic members 31a and 31b. By this pulling, the fixing roller 17 and the pressure roller 18 are in a low-pressure contact state, that is, a state where the nip N width is small.

  In this embodiment, the first operating body 51 is composed of a rod 60 disposed in parallel with the axial direction of the roller pair 30 as shown in FIG. In this case, the rod 60 reciprocates in the directions of arrows B1 and B2 along the axial direction of the rod 60. The rod 60 includes a rod body 60a and a shaft portion 60b that is connected to the distal end side of the rod body 60a.

  The rod body 60a of the rod 60 is provided with elongated holes 61, 61 extending in the axial direction, and fixing pins 62, 62 are fitted into the elongated holes 61, 61. For this reason, the rod 60 reciprocates by the stroke of the long holes 61 and 61. In this case, the return means 65 presses in the arrow B2 direction. Therefore, in this state, the rod 60 moves in the arrow B2 direction, and the fixing pins 62 and 62 come into contact with the end edge of the elongated holes 61 and 61 on the return means 65 side. The return means 65 includes a spring member (compression spring) 67 disposed between the base portion 66 provided on the apparatus main body side and the proximal end side of the rod 60.

  As shown in FIG. 2, the second operating body 52 includes a swing block 68 that swings (rotates) around the shaft portion 60 b of the rod 60. The swing block 63 is provided with a detection rod 69 that is detected by the detection means 53. That is, as shown in FIG. 2A, the state rotated in the direction of the arrow C1 is a state that can be detected by the detecting means 53, and as shown in FIG. 2B, the state rotated in the direction of the arrow C2. The state is a state in which detection by the detection means 53 is impossible.

  Incidentally, as shown in FIG. 1, the rod 60, that is, the first operating body 51 and the first operating lever 45 a are connected by the first link mechanism 71, and the swing block 68, that is, the second operating body 52. And the second operating lever 45 b are connected by a second link mechanism 72.

  The first link mechanism 71 is configured by an L-shaped block piece 74 in a plan view, and swings around a shaft portion 73 disposed at a corner portion thereof. In the block piece 74, one piece 74a comes into contact with the operation lever 45a, and a pin member 77 provided on the proximal end side of the rod body 60a of the rod 60 is loosely fitted into the long hole 76 provided in the other piece 74b. Match.

  For this reason, if the low pressure contact state shown in FIG. 4B is obtained by rotating the operation lever 45a in the direction of the arrow A2 from the high pressure contact state shown in FIG. The first link mechanism 71 rotates in the arrow D2 direction via the lever 45a. At this time, since the pin member 77 is fitted in the long hole 76, the rod 60 slides in the direction of the arrow B2 as shown in FIG. If the operation lever 45a is rotated in the direction of arrow A1 from the state shown in FIG. 1B, the link mechanism 71 is rotated in the direction of arrow D1, and the rod 60 is slid in the direction of arrow B1, 1 (a) state.

  As shown in FIGS. 1 and 2, the second link mechanism 72 includes a swing arm 81 whose base is pivotally supported by a pivot shaft 80 and swings in the directions of arrows E1 and E2. In this case, the second link mechanism 72 has a spring member 82 that urges the swing arm 81 to swing in the direction of arrow E2.

  Therefore, when the second operating lever 45b is rotated in the direction of arrow A1 (see FIG. 2A), as shown in FIG. 1A, the swing arm 81 swings in the direction of arrow E1. As a result, the swing block 68 swings in the direction of the arrow C1. On the other hand, when the second operating lever 45b is rotated in the direction of arrow A2 (see FIG. 2B), the swing arm 81 swings in the direction of arrow E2 and swings. The block 68 swings in the direction of arrow C2.

  In this way, when the first operating lever 45a is operated to rotate in the arrow A1 direction and the rod 60 is slid in the arrow B1 direction as shown in FIG. By operating the operation lever 45b and rotating it in the direction of the arrow A1 as shown in FIG. 2 (a), the detection means 53 detects the second operating body 52 as shown in FIG. 2 (a). Becomes possible. On the other hand, if the first operating lever 45a is not in the state shown in FIG. 2A but in the state shown in FIG. 2B, the rod 60 is sliding in the arrow B2 direction. Therefore, in this state, even if the second operating lever 45b is rotated in the direction of the arrow A1, the state shown in FIG. 52 cannot be detected.

  By the way, in this embodiment, when the axial slide range (slide amount) of the rod 60 is H1, and the contact range between the swing arm 81 and the swing block 68 is H2, H1 <H2.

In this embodiment, the detecting means 53 uses a transmissive non-contact sensor 90. That is, as shown in FIG. 2, a projector 85 that projects light such as visible light and infrared light, and a light receiver 86 that receives light from the projector 85, and as shown in FIG. When the detection rod 69 enters between 85 and the light receiver 86,
This state is detected by blocking the light projected from the projector 85.

  On the other hand, as shown in FIG. 2B, when the swing block 68 is suspended, that is, when the operation lever 45b is secondly operated in the arrow A2 direction, the light projector 85, the light receiver 86, and During this period, the detection rod 69 does not enter, the light projected from the projector 85 is not blocked, and the detection by the sensor 90 cannot be performed.

  In the fixing device of this embodiment, the nip pressure can be adjusted by operating a pair of operating levers 45a and 45b disposed on both ends of the roller pair 30 in the axial direction. Therefore, a uniform pressure can be applied over the entire length in the axial direction, and a stable fixing function can be exhibited. The detection means 53 can detect that both the first operation 45a and the second operation have been performed, and both the first operation lever and the second operation lever 45b (both ) Is operated or not, and the dynamic state of the roller pair 30 can be detected. That is, since any one of the operating levers is not operated and the dynamic state of the roller pair 30 is not detected, the fixing operation is performed assuming that the nip pressure is changed while any one of the operating levers is not operated. Can be prevented. In addition, since only one detector means 53 is required, it is possible to reduce the size. That is, it is possible to provide a fixing device capable of stably controlling the nip pressure on the roller pair 30 with a simple configuration at low cost.

  The first operation may be a linear operation, and the second operation may be a rotation operation, so that the mechanism can be simplified and cost reduction and compactness can be achieved.

  By connecting the operation levers 45a and 45b and the operating bodies 51 and 52 with the link mechanisms 71 and 72, the operation (operation) of the operating levers 45a and 45b can be stably transmitted to the operating bodies 51 and 52. In addition, the mechanism can be simplified.

  In the case where the return means 65 is provided, the operation levers 45a and 45b can be stably returned to the initial state, and the nip pressure can be stably adjusted.

  By setting H1 <H2, the first operation of the operating body 51 by the first operation lever 45a can be performed via the first link mechanism 71 irrespective of the operation operation of the second operation lever 45b. Can be set. As a result, the reliability of the operation by the first operation lever 45a can be improved.

  Next, FIGS. 5 and 6 show a second fixing device. In this case, a sensor 90 constituting the detecting means 53 is attached to the swing block 68 that is the second operating body 52. Therefore, the blocking member 91 is provided on the apparatus main body 100 side, and as shown in FIG. 6A, the light projector 85 and the light receiver 86 of the sensor 90 in a state where the swing block 68 swings in the direction of the arrow C1. The blocking member 91 is interposed between the swing block 68 and the swing block 68 is detected. Further, as shown in FIG. 6B, when the swing block 68 is swung in the direction of the arrow C2, it is not interposed between the light projector 85 and the light receiver 86 of the sensor 90, and the swing block 68 is swung. The block 68 is not detected.

  Next, FIGS. 7 and 8 show a third fixing device. In this case, the blocking member 92 is provided on the rod 60. As shown in FIGS. 7A and 8A, when the swing block 68 pivotally supported by the pivot shaft 70 swings in the direction of the arrow C1, the light projector 85 and the light receiver of the sensor 90 are received. In this state, the blocking member 92 is interposed between the rocker 86 and the swinging block 68 is detected. Further, as shown in FIGS. 7B and 8B, the blocking member 92 is interposed between the light projector 85 and the light receiver 86 of the sensor 90 in a state where the swing block 68 swings in the direction of the arrow C2. Is in a state where no swing block 68 is detected.

  In the third fixing device, the first link mechanism 71 uses a swing arm 93 different from the first and second fixing devices. As shown in FIG. 7, the swing arm 93 has a wide portion 93a that bulges toward the side opposite to the base portion at the intermediate portion in the length direction, and is opposite to the wide portion 93a. It is pivotally supported on a pivot shaft 94 on the base side. A long hole 84 is provided on the rod side of the swing arm 93, and a pin member 94 of the rod 60 is fitted in the long hole 84.

  For this reason, from the state shown in FIG. 7B, the swing arm 93 swings in the arrow D2 direction around the pivot shaft 94, so that the rod 60 slides in the arrow B2 direction. It will be in the state shown in Further, from the state shown in FIG. 7A, the swing arm 93 swings in the direction of arrow D1 about the pivot shaft 94, so that the rod 60 slides in the direction of arrow B1 and FIG. 7B. It will be in the state shown in

  As described above, both the fixing device shown in FIGS. 5 and 6 and the fixing device shown in FIGS. 7 and 8 have the same effects as the fixing devices shown in FIGS. .

  FIG. 9 shows a fourth fixing device, in which the second operating body 52 is composed of a swinging body 95 that rotates about an axis in a direction orthogonal to the axial center direction of the rod 60. That is, as shown in FIG. 9A, when the elastic members 31a and 31b are contracted and the roller pair 30 is in a high pressure contact state, the swinging body 95 has its axis centered via the second operating body 52. Rotating around L 1, the shielding portion 95 a provided on the rocking body 95 is placed between the light projector 85 and the light receiver 86 of the sensor 90.

  Further, from the state shown in FIG. 9A, if the operating lever 45a is operated to extend the elastic members 31a and 31b, the rod 60 is slid in the arrow B2 direction. In this state, the oscillating body 95 rotates about its axis L1, and the shielding portion 95a does not face the sensor 90. In this state, even if the second link mechanism 72 is operated, the oscillating body 95 cannot be rotated around its axis.

  However, as shown in FIG. 9 (a), when the rod 60 is slid in the direction of the arrow B1, if the second operating lever 45b is brought into a state in which the elastic member 31b is contracted, the rocking body 95 rotates around its axis. Can be rotated.

  Note that the second link mechanism 72 in this case includes an inverted L-shaped block piece 96 composed of a first piece 96a and a second piece 96b in plan view. The block piece 96 has a first piece 96 a pivoted on a pivot shaft 97. For this reason, the block piece 96 rotates (swings) about the pivot shaft 97 in the directions of arrows E1 and E2.

  Therefore, as shown in FIG. 9A, only when the rod 60 is slid in the direction of the arrow B1, the operation of the second operating lever 45b causes the arrow E2 from the state shown in FIG. If rocked by the method, the rocking body 95 can be rotated around its axis.

  Also in FIG. 10, the second operating body 52 is configured by a rocking body 98 that rotates about an axis L <b> 2 in a direction orthogonal to the axis direction of the rod 60. In this case, the axis L2 is orthogonal to the axis L1 of the rocking body 95 shown in FIG.

  In addition, the link mechanism 72 includes a swinging arm 99 having an L-shaped shape that includes a first piece 99a and a second piece 99b. In this case, in the link mechanism 72, the first piece 99a is pivotally supported by the pivot shaft 101, and swings in the directions of arrows E1 and E2. A protrusion 102 is provided on the first piece 99 a of the swing arm 99.

  The oscillating body 98 has a tapered surface 98 a that is in sliding contact with the protrusion 102. Therefore, as shown in FIG. 10A, when the second operating lever 45b is operated so that the swing arm 99 swings in the arrow E1 direction with the rod 60 slid in the arrow B1 direction. The protrusion 102 of the swing arm 99 is in sliding contact with the tapered surface 98 a of the swing body 98. As a result, the oscillating body 98 oscillates around the pivot shaft 101 in the direction of the arrow F1 and is inserted between the light projector 85 and the light receiver 86 of the sensor 90, and detection by this sensor 90 becomes possible.

  In this case, as shown in FIG. 10B, with the rod 60 slid in the arrow B2 direction, the second operating lever 45b is operated to swing the swing arm 99 in the arrow E1 direction. Since the protrusion 102 of the swing arm 99 is located away from the tapered surface 98a of the swing body 98, the swing body 98 cannot be swung in the direction of arrow F1. In contrast, if the rod 60 is slid in the arrow B1 direction as shown in FIG. 10A, the second operating lever 45b is operated to swing the swing arm 99 in the arrow E1 direction. In this case, the protrusion 102 of the swing arm 99 comes into sliding contact with the tapered surface 98a of the swing body 98.

  Therefore, the fixing device shown in FIGS. 9 and 10 and the fixing device shown in FIGS. 7 and 8 have the same effects as the fixing device shown in FIGS. . In the fixing device shown in FIG. 1 and the like, the linear sliding direction of the first operation and the rotational axis direction of the second operation are arranged in parallel to each other. In the fixing device shown in FIG. 1, the linear sliding direction of the first operation and the rotational axis direction of the second operation are arranged orthogonally. Thus, it may be arranged in parallel or orthogonally, and the degree of freedom of design of this device is increased.

  Next, FIG. 11 shows that the detecting means 53 is arranged on the first operating lever 45a side. That is, the rod 60 includes a rod body 60a having long holes 61 and 61, and a shaft member 60c inserted through the rod body 60a. And the shaft member 60c protrudes from the axial direction both ends of the rod main body 60a. A swing block 68 provided with a detection rod 69 is disposed on the protruding portion 105a on the first operation lever 45a side. In addition, a rotating body 106 that rotates the shaft member 60c about its axis by the contact of the second link mechanism 72 is disposed on the protruding portion 105b on the second operation lever 45b side.

  The state shown in FIG. 11B is a state in which the first operation lever 45a and the second operation lever 45b are operated in the direction in which the elastic members 31a and 31b pull, and the nip width is reduced. In this state, the swing block 68 is in a state where the detection rod 69 is not disposed between the light projector 85 and the light receiver 86 of the sensor 90.

  In this state, when the first operating lever 45a is operated in a direction to contract the elastic member 31a, the rod 60 is slid in the direction of the arrow B1 via the link mechanism 71 by the swing of the operating lever 45a. In this manner, in the state where the rod 60 is slid in the direction of the arrow B1, the second operating lever 45b is operated in the direction in which the elastic member 31a is contracted, whereby the operating lever 45b is the second link mechanism 72. The moving arm 81 is swung around the pivot shaft 80 in the direction of arrow E1. As a result, the rotating body 106 is brought into sliding contact with the swing arm 81, and the shaft member 60c is rotated about its axis. By rotating in this way, the swing block 68 on the protruding portion 105a side rotates, and the detection rod 69 of the swing block 68 is connected to the projector 85 of the sensor 90 as shown in FIG. It will be in the state arrange | positioned between the light receivers 86. FIG.

  However, as shown in FIG. 11B, when the rod 60 is slid in the direction of the arrow B2, the second operating lever 45b is swung in the direction of contracting the elastic member 31b as shown in FIG. Even if it is moved, the rotating body 106 cannot be rotated by the swing arm 81. That is, if the rod 60 is not slid in the direction of the arrow B2 as shown in FIG. 11A by the operation of the first operation lever, the sensor 90 can be detected by the second operation lever. I can't.

  Therefore, even the fixing device shown in FIG. 11 has the same effects as the fixing device shown in FIGS.

  Next, FIG. 12 and FIG. 13 show a case where a contact type is used for the detection means 53. In this case, it is a button type switch (mechanical switch) 110. That is, when the swing block 68 is inclined as shown in FIG. 12 (the state shown in FIG. 2A), the button 110a of the switch 110 is changed to the state shown in FIG. As shown, the pressing portion 68a of the swing block 68 is pressed. Accordingly, it is detected that the first operation lever 45a and the second operation lever 45b are operated and the state shown in FIG. 1 (a) or 2 (a) is obtained.

  As shown in FIG. 13B, when the swing block 68 is in a hanging shape, the pressing portion 68a does not press the button 110a of the switch 110, and the non-detection state is obtained.

  Next, FIG. 14 and FIG. 15 show a case where a reflection type non-contact sensor 111 is used as the detection means 53. The sensor 111 includes a projector 111a that projects light such as visible light and infrared light, and a light receiver 111b that receives the light.

  That is, as shown in FIGS. 14 and 15A, when the reflecting portion 68 b of the swing block 68 faces the sensor 111, the light L projected from the projector 111 a is reflected by the reflecting portion of the swing block 68. The light hits 68b, is reflected, and enters the light receiver 111b. Accordingly, it is detected that the first operation lever 45a and the second operation lever 45b are operated and the state shown in FIG. 1 (a) or 2 (a) is obtained.

  On the other hand, as shown in FIG. 15B, when the swing block 68 is in a suspended state, the reflecting portion 68b is separated from the sensor 111. In such a separated state, the light L projected from the projector 111a does not strike the reflecting portion 68b and does not enter the light receiver 111b. For this reason, it will be in a non-detection state.

  For this reason, even if the sensor 110 shown in FIGS. 12 and 13 and the sensor 111 shown in FIGS. 14 and 15 are used, the same effects as the sensor 90 shown in FIG.

  As described above, a non-contact type sensor or a contact type sensor may be used for the detecting means 53, and the degree of freedom in design of the apparatus is increased.

  In the image forming apparatus of the present invention, a high-quality image forming apparatus can be provided by including the fixing device that exhibits the above-described effects.

  In addition, this invention is not limited to the above-mentioned Example, Of course, a various change can be added in the range which does not deviate from the summary of this invention. Examples of the image forming apparatus according to the present invention include an electrophotographic copying machine, a laser beam printer, and a facsimile machine. In the case where a non-contact type sensor is used as the detecting means 53, the light emitting device 85 and the light receiving device 86 are provided in the above-described embodiment. A high frequency oscillation type using induction, a magnetic type using a magnet, or a capacitance type proximity sensor using a change in capacitance may be used. Further, when a contact type sensor is used as the detection means 53, a differential transformer method may be used.

16 Fixing device 17 Fixing roller 18 Pressure roller 30 Roller pair 45a, 45b Operation lever 50 Adjusting means 51, 52 Operating body 53 Detection means 65 Restoring means 71, 72 Link mechanism 90, 111 Non-contact sensor 97 Pivoting shaft 110 Contact Type sensor N Fixing nip

Japanese Patent Publication No. 5-19712 JP 2009-244514 A JP 2009-139682 A

Claims (9)

A roller pair in which a pair of rollers are arranged side by side to form a nip, and an adjusting unit that adjusts the nip pressure by an operation with a pair of operation levers disposed on both ends in the axial direction of the roller pair. A fixing device,
The adjusting means performs a first operation body that performs a first operation that is a linear operation in conjunction with the first operation lever, and a second operation that performs a rotation operation in conjunction with the second operation lever. A fixing device comprising: a second operation body; and one detection unit that detects that both the first operation and the second operation are performed. The fixing device according to claim 1, wherein the linear sliding direction of the first operation and the rotational axis direction of the second operation are arranged in parallel or orthogonal to each other . The first operating lever and the first operating body are connected via a first link mechanism that converts the operation of the operating lever into a first operation. The fixing device described. The second operating lever and the second operating body are connected via a second link mechanism that converts the operation of the operating lever into a second operation . The fixing device according to claim 1. 5. The fixing device according to claim 1 , further comprising return means for returning the link mechanism to an initial position and returning an operation lever position to the initial position . 6. The operation of the first operating body by the first operating lever is set so as to be performed via the first link mechanism regardless of the operation of the second operating lever. The fixing device according to claim 5. The fixing device according to claim 1 , wherein a non-contact type sensor is used as the detection unit . The fixing device according to claim 1 , wherein a contact-type sensor is used as the detection unit. An image forming apparatus comprising the fixing device according to claim 1 .

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