JP4839173B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus, and in particular, a fixing device in which a temperature detection member of a fixing roller is disposed at a longitudinal end portion of the fixing roller and a heat transfer member is in contact with a part of the surface of the fixing roller. The present invention also relates to an image forming apparatus including the fixing device.

  In an image forming apparatus using an electrophotographic system, a heat roller type fixing device is often used as a fixing device for fixing a toner image transferred onto a recording sheet. Such a fixing device has a heat source inside, and press-rotates a pressure roller and a fixing roller formed of a material having a releasability with respect to the toner, such as silicone rubber or fluorine resin, so that the pressure-contact portion of both rollers The unfixed toner image on the recording paper that passes through the nip is heated and pressed to be fixed. In this heat roller type fixing device, since the surface of the fixing roller and the toner image on the recording paper come into contact with each other under pressure, the thermal efficiency when fusing the toner image on the recording paper is extremely good, and the fixing is performed quickly. This is very effective in a high-speed electrophotographic copying machine.

  When the image is continuously formed on a recording paper having a small size with respect to the width of the fixing roller and passes through the fixing device, the fixing device in which the temperature detection member is disposed at the center portion in the longitudinal direction of the fixing roller is When the temperature rises excessively, early deterioration of the fixing roller and the pressure roller surface layer occurs. In addition, since the heat energy generated from the heating source is used to increase the temperature of the portion where the recording paper does not pass, the energy efficiency becomes very poor. Further, the surface layer at the center of the fixing roller is worn by the contact of the temperature detection member, the life of the fixing roller is shortened, and is not suitable for a high-speed electrophotographic copying machine or the like.

When an image is continuously formed on a recording paper having a small size with respect to the width of the fixing roller and passes through the fixing device, the fixing device in which the temperature detection member is arranged at the end portion in the longitudinal direction of the fixing roller has a roller central portion ( The fixing property deteriorates due to a decrease in the fixing roller temperature in the transfer paper passage portion. Since the center portion of the fixing roller is not worn, the life is longer than that of the above configuration, but there is a problem that the responsiveness of the temperature detection member is inferior to the temperature of the center portion of the fixing roller.

  As a countermeasure, it is considered to insert a heat pipe inside the fixing roller. However, if the heat pipe is inserted, the fixing roller becomes an expensive part. Since this fixing roller is a component that is frequently replaced due to wear of its surface layer, adhesion of toner or paper powder, etc., if the fixing roller becomes expensive, the replacement cost increases.

  In order to suppress the replacement cost, it has been proposed to arrange a heat transfer member in contact with a part of the surface of the fixing roller so as to make the temperature of the fixing roller uniform. In this case, it is desirable that the heat transfer member is brought into contact with the entire width of the fixing roller. Further, by using a heat pipe member (roller) or an aluminum member (roller) as the heat transfer member, the effect of making the temperature of the fixing roller uniform efficiently is improved (see Patent Document 1).

  FIG. 15 is a schematic sectional view showing a conventional fixing device. In this fixing device, the fixing roller 1 incorporates a heater 3, detects the temperature of the fixing roller 1 by a temperature detection member 4, and is controlled to a constant temperature by a temperature control device (not shown). The surface of the fixing roller 1 is covered with a releasable material. A pressure roller 2 whose surface is covered with an elastic material is pressed against the fixing roller 1. When an unfixed toner 6 as an unfixed image passes through the fixing roller 1, the toner melts and receives pressure to transfer paper 5. To settle. A heat pipe is inserted into the fixing roller 1 or a heat transfer member 7 made of a heat pipe member or an aluminum member is brought into contact with the fixing roller 1 to make the temperature distribution of the fixing roller uniform when a small size paper is passed.

  FIG. 16 is a schematic sectional view showing another example of a conventional fixing device. In this example, the heat transfer member 7 is disposed immediately above the heater 3 in the fixing device. Such a configuration is also described in Patent Document 2.

Further, in Patent Document 3, a temperature detection unit is disposed at an end portion in the axial direction of a heat roller that is a fixing roller, and is made of a metal as a heat conduction member upstream of the temperature detection unit in the rotation direction of the fixing roller. A heating roller is described on the side of the heat source of the fixing roller.
JP-A-6-348176 JP 2005-099136 A JP 2004-93709 A

  However, although the heat pipe member and the roller-shaped aluminum member, which are the heat conducting members described above, have good heat transfer in the longitudinal direction, they also have good heat transfer in the thickness direction, that is, the radial direction and the circumferential direction. For this reason, heat is conducted from the fixing roller to the heat transfer member, and the amount of heat that escapes from the heat transfer member into the surrounding atmosphere also increases. Therefore, although the effect of making the temperature distribution in the longitudinal direction of the fixing roller uniform is improved, the temperature decreases as a whole, resulting in a decrease in thermal efficiency. In particular, in the configuration described in Patent Document 2, since the heat transfer member is disposed immediately above the heat source of the fixing roller, the heat escape from the heat transfer member to the atmosphere is the largest.

  Moreover, although the thing of the patent document 3 has arrange | positioned the heating roller which is a heat conductive member in the side of a heat source avoiding just above a heat source, the thermal radiation from a heat conductive member cannot be avoided.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device and an image forming apparatus that can prevent heat conduction from a heat roller to a heat conducting member as much as possible, and that can reduce heat radiation from the heat conducting member.

  According to a first aspect of the present invention, in the fixing device, the temperature detection member of the fixing roller is disposed at the end portion in the longitudinal direction of the fixing roller, and the heat transfer member is disposed in contact with a part of the surface of the fixing roller. In the fixing device, a plurality of members having different thermal conductivities are alternately arranged along a circumferential direction on a heat insulating resin heat insulating layer.

  According to a second aspect of the present invention, in the fixing device according to the first aspect, the heat transfer member is upstream of the fixing roller temperature detecting member in the rotation direction of the fixing roller and a nip portion between the fixing roller and the pressure roller. It is characterized in that it is arranged at a position further downstream than the heat source of the fixing roller.

  According to a third aspect of the present invention, there is provided the fixing device according to the first aspect, wherein the heat transfer member is upstream of the fixing roller rotation direction with respect to the temperature detecting member of the fixing roller and from a nip portion between the fixing roller and the pressure roller. It is arranged downstream and below the fixing roller.

  According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, a driving unit for operating the heat transfer member, a position detecting unit for detecting a rotational position of the heat conducting member, and the It is characterized in that it comprises a rotation control means for controlling only the driving means so that only the low thermal conductivity member region of the heat transfer member abuts against the fixing roller while the rotation of the fixing roller is stopped.

  According to a fifth aspect of the present invention, in the fixing device according to any one of the first to third aspects, the heat transfer member is configured to rotate with the fixing roller, and a position detection unit that detects a rotational position of the heat conductive member. And a rotation control means for controlling the driving means of the fixing roller to control only the low thermal conductivity member region of the heat transfer member to contact the fixing roller when the fixing roller stops rotating. To do.

  According to a sixth aspect of the present invention, in the fixing device according to any one of the first to fifth aspects, the plurality of members having different thermal conductivities of the heat conducting member are an aluminum-based material and an iron-based material.

  According to a seventh aspect of the present invention, in the fixing device according to any one of the first to fifth aspects, the plurality of members having different thermal conductivities of the heat conducting member are an aluminum-based material and a heat-resistant resin material.

  The invention according to claim 8 is the fixing device according to claim 6 or 7, wherein an air layer is provided inside the iron-based material and the heat-resistant resin material.

  A ninth aspect of the present invention is an image forming apparatus comprising the fixing device according to the first to eighth aspects.

  According to the fixing device and the image forming apparatus according to the present invention, since the heat transfer member is configured by alternately arranging a plurality of members having different thermal conductivities on the heat-resistant resin heat insulating layer, the contact portion with the fixing roller The heat transfer from the heat transfer member to the heat conduction member and the heat transfer to the atmosphere can be reduced.

  Embodiments as the best mode for carrying out the present invention will be described below with reference to the drawings.

  Embodiments of a fixing device according to the present invention will be described below with reference to the drawings.

<Example 1>
FIG. 1 is a sectional view conceptually showing an image forming apparatus such as an electrophotographic copying machine or printer according to the present invention. The image forming apparatus according to the present embodiment mainly includes a reading unit 111 that reads a document, an image forming unit 112 that forms an image, an automatic document feeder (ADF) 113, and a document that stacks documents sent from the ADF 113. A paper discharge tray 114, a paper supply unit 119 including paper supply cassettes 115 to 118, and a paper discharge unit (discharge tray 120) for stacking recording paper are configured.

Then, when the document D is set on the document table 121 of the ADF 113 and an operation unit (not shown) is operated, for example, a press of a print key is performed, the uppermost document D is sent out in the direction of the arrow B 1 by the rotation of the pickup roller 122. Then, by the rotation of the document conveying belt 123, the paper is fed onto the contact glass 124 fixed to the image reading unit 111 and stops there. The image of the document D placed on the contact glass 124 is read by a reading device 125 positioned between the image forming unit 112 and the contact glass 124. The reading device 125 includes a light source 126 that illuminates the document D on the contact glass 124, an optical system 127 that forms an image of the document, a photoelectric conversion element 128 that includes a CCD that forms an image of the document, and the like. After the image reading is completed, the document D is transported in the direction of arrow B2 by the rotation of the transport belt 123 and discharged onto the paper discharge tray 114. In this way, the document D is fed one by one onto the contact glass 124 and the document image is read by the image reading unit 111.

On the other hand, inside the image forming unit 112, a photoreceptor 130 as an image carrier is disposed. The photoconductor 130 is driven to rotate clockwise in the drawing, and the charging device 131 charges the surface to a predetermined potential. Further, the writing unit 132 emits laser light L that is light-modulated in accordance with image information read by the reading device 125, and the surface of the charged photosensitive member 130 is exposed with the laser light L, whereby the photosensitive member is exposed. An electrostatic latent image is formed on the surface 130. When the electrostatic latent image passes through the developing device 133, the electrostatic latent image is transferred to the recording medium P fed between the photosensitive member 130 and the transfer device 134 by the opposing transfer device 134. The surface of the photoreceptor 130 after the toner image transfer is cleaned by a cleaning device 135.

A plurality of paper feed cassettes 115 to 118 disposed below the image forming unit 112 contain recording media P such as paper, and the recording media P is fed from any of the paper feed cassettes 115 to 118 in the direction of arrow B3. The toner image formed on the surface of the photoreceptor 130 as described above is transferred onto the surface of the recording medium P. Next, the recording medium P is passed through the fixing device 10 in the image forming unit 112 as indicated by an arrow B4, and the toner image transferred to the surface of the recording medium P by the action of heat and pressure is fixed. The recording medium P that has passed through 136 is conveyed by the discharge roller pair 137, discharged to the discharge tray 120 as shown by an arrow B5, and stacked.

  2A and 2B are diagrams illustrating the configuration of the fixing device according to the first embodiment, in which FIG. 2A is a schematic sectional view, and FIG. 2B is a front view. In this example, the fixing device includes a fixing roller 1 including a heater 3, a pressure roller 2 that is pressed against the fixing roller 1, a temperature detection member 4 that detects the temperature of the fixing roller 1, and the surface of the fixing roller 1. And a heat transfer member 11 that is press-contacted. The heater 3 is controlled to have a constant temperature by a temperature control device based on a temperature detected by a temperature detection member 4 (not shown).

  The surface of the fixing roller 1 is covered with a releasable material. The surface of the pressure roller 2 is covered with an elastic material. A nip portion is formed between the fixing roller 1 and the pressure roller 2, and the transfer paper 5 onto which the unfixed toner 6 is transferred passes between the guide members and passes through the nip portion. The unfixed toner 6 melts at the nip portion, and is fixed to the transfer paper 5 under pressure.

  In this example, the temperature detection member 4 is disposed at the end of the fixing roller 1 in the longitudinal direction. Further, the heat transfer member 11 is disposed on the upstream side in the rotation direction of the fixing roller 1 with respect to the temperature detection member 4 of the fixing roller 1 and on the downstream side from the nip portion between the fixing roller 1 and the pressure roller 2. The heat transfer member 11 is disposed at a position avoiding directly above the heater 3 that is a heat source of the fixing roller 1, that is, obliquely above the heater 3.

  FIG. 3 is a graph showing the temperature distribution of the fixing roller in the fixing device according to the first embodiment in comparison with the conventional fixing roller. According to the fixing device according to the embodiment, the temperature of the central portion (portion through which the paper has passed) of the fixing roller 1 rises, and the temperature of the position of the temperature detection member (outside the paper passage) falls below the set temperature range. By turning on, the temperature of the fixing roller rises, and a temperature drop within the sheet passing range can be prevented. On the other hand, in the fixing device according to the conventional example, the temperature outside the sheet does not decrease when the small-size continuous sheet is passed, so the fixing heater is turned off and the temperature within the sheet passing range is lowered.

  Furthermore, in this embodiment, the heat transfer member 11 is disposed at the side of the fixing roller 1 that is the highest temperature portion and has a large amount of heat transfer, and avoids the heater 3 of the fixing roller 1. The release of heat from the transmission member to the atmosphere can be reduced.

<Example 2>
FIGS. 4A and 4B are views showing a second embodiment of the fixing device according to the present invention, in which FIG. 4A is a schematic sectional view, and FIG. 4B is a front view. In this example, as in the first embodiment, the fixing device includes a fixing roller 1 incorporating a heater 3, a pressure roller 2 that is pressed against the fixing roller 1, and a temperature detection that detects the temperature of the fixing roller 1. A member 4 and a heat transfer member 11 pressed against the surface of the fixing roller 1 are provided. The heater 3 is controlled to have a constant temperature by a temperature control device based on a temperature detected by a temperature detection member 4 (not shown).

  The surface of the fixing roller 1 is covered with a releasable material. The surface of the pressure roller 2 is covered with an elastic material. A nip portion is formed between the fixing roller 1 and the pressure roller 2, and the transfer paper 5 onto which the unfixed toner 6 is transferred passes between the guide members and passes through the nip portion. The unfixed toner 6 melts at the nip portion, and is fixed to the transfer paper 5 under pressure.

  In this example, the temperature detection member 4 is disposed at the end of the fixing roller 1 in the longitudinal direction. Further, the heat transfer member 11 is disposed on the upstream side in the rotation direction of the fixing roller 1 with respect to the temperature detection member 4 of the fixing roller 1 and on the downstream side from the nip portion between the fixing roller 1 and the pressure roller 2. The heat transfer member 11 is disposed below the heater 3 of the fixing roller 1, that is, below the horizontal plane passing through the center of the fixing roller 1.

  In this embodiment, since the heat transfer member 11 is disposed at the lowermost portion, which is the highest temperature portion and has a large amount of heat transfer, avoiding directly above the heater 3 of the fixing roller 1, heat is transferred from the heat transfer member to the atmosphere. Release can be reduced.

<Example 3>
FIGS. 5A and 5B are views showing a third embodiment of the fixing device according to the present invention, in which FIG. 5A is a schematic sectional view, and FIG. 5B is a front view. In this example, as in the first embodiment, the fixing device includes a fixing roller 1 incorporating a heater 3, a pressure roller 2 that is pressed against the fixing roller 1, and a temperature detection that detects the temperature of the fixing roller 1. A member 4 and a heat transfer member 11 pressed against the surface of the fixing roller 1 are provided. The heater 3 is controlled to have a constant temperature by a temperature control device based on a temperature detected by a temperature detection member 4 (not shown).

  The surface of the fixing roller 1 is covered with a releasable material. The surface of the pressure roller 2 is covered with an elastic material. A nip portion is formed between the fixing roller 1 and the pressure roller 2, and the transfer paper 5 onto which the unfixed toner 6 has been transferred passes through the nip portion. The unfixed toner 6 melts at the nip portion, and is fixed to the transfer paper 5 under pressure.

  In this example, the temperature detection member 4 is disposed at the end of the fixing roller 1 in the longitudinal direction. Further, the heat transfer member 11 is disposed on the upstream side in the rotation direction of the fixing roller 1 with respect to the temperature detection member 4 of the fixing roller 1 and on the downstream side from the nip portion between the fixing roller 1 and the pressure roller 2. The heat transfer member 11 is disposed at a position avoiding the heater 3 directly above the fixing roller 1, that is, obliquely above the heater 3.

  FIG. 6 is a schematic cross-sectional view showing the configuration of the heat transfer member. The heat transfer member 11 is configured by alternately arranging a high thermal conductivity material 13 and a low thermal conductivity material 14 on a resin heat insulating layer 12. In this example, an aluminum-based material is used as the high thermal conductivity material, and an iron-based material is used as the low thermal conductivity material. Further, an aluminum-based material can be used as the high thermal conductivity material, and a heat resistant resin material can be used as the low thermal conductivity material.

  In the present embodiment, the heat transfer member 11 is disposed at an obliquely upper position avoiding directly above the heater 3 of the fixing roller 1, which is the highest temperature portion and has a large amount of heat transfer, so that heat is transferred from the heat transfer member to the atmosphere. Can be reduced. Further, since the heat transfer member 11 is configured by alternately arranging the high heat conductivity material 13 and the low heat conductivity material 14, heat conduction is suppressed by the low heat conduction portion, and heat is transferred from the contact portion of the fixing roller of the heat transfer member. The heat transfer in the circumferential direction in the conductive member is suppressed, and the release of heat to the atmosphere can be further reduced.

<Example 4>
FIGS. 7A and 7B are diagrams showing a fourth embodiment of the fixing device according to the present invention. FIG. 7A is a diagram showing a control block and a schematic cross section, and FIG. 7B is a front view. In this example, as in the first embodiment, the fixing device includes a fixing roller 1 incorporating a heater 3, a pressure roller 2 that is pressed against the fixing roller 1, and a temperature detection that detects the temperature of the fixing roller 1. A member 4 and a heat transfer member 11 pressed against the surface of the fixing roller 1 are provided. The heater 3 is controlled to have a constant temperature by a temperature control device based on a temperature detected by a temperature detection member 4 (not shown).

  The surface of the fixing roller 1 is covered with a releasable material. The surface of the pressure roller 2 is covered with an elastic material. A nip portion is formed between the fixing roller 1 and the pressure roller 2, and the transfer paper 5 onto which the unfixed toner 6 has been transferred passes through the nip portion. The unfixed toner 6 melts at the nip portion, and is fixed to the transfer paper 5 under pressure.

  In this example, the temperature detection member 4 is disposed at the end of the fixing roller 1 in the longitudinal direction. Further, the heat transfer member 11 is disposed on the upstream side in the rotation direction of the fixing roller 1 with respect to the temperature detection member 4 of the fixing roller 1 and on the downstream side from the nip portion between the fixing roller 1 and the pressure roller 2. The heat transfer member 11 is disposed at a position avoiding the heater 3 directly above the fixing roller 1, that is, obliquely above the heater 3.

  FIG. 8 is a schematic cross-sectional view showing the configuration of the heat transfer member. The heat transfer member 11 is configured by alternately arranging a high thermal conductivity material 13 and a low thermal conductivity material 14 on a resin heat insulating layer 12. In this example, an aluminum-based material is used as the high thermal conductivity material, and an iron-based material is used as the low thermal conductivity material. Further, an aluminum-based material can be used as the high thermal conductivity material, and a heat resistant resin material can be used as the low thermal conductivity material.

  In this example, the heat transfer member 11 is rotationally driven by a drive source 31 as shown in FIG. The drive source 31 is provided separately from the drive source 32 of the fixing roller 1, and the drive source 31 and the drive source 32 are driven and controlled by the control unit 33. The control means 33 is connected to detection means 34 for detecting the rotational position of the heat transfer member 11, and the control means 33 drives the drive source 31 based on the connection detection result of the detection means 34.

  9A and 9B are diagrams showing the configuration of the detection means, where FIG. 9A is a schematic plan view, and FIG. 9B is a schematic side view. The detection unit 34 is rotated in synchronization with the heat transfer member 11, and includes a filler 21 having a slit and a photosensor 22 installed in the vicinity of the filler 21. The detection means 34 detects the position where the low thermal conductivity material 14 is disposed, and the control means 33 controls the rotation of the drive source 31 to reduce the low heat of the heat transfer member 11 when the rotation of the fixing roller 1 is stopped. The heat transfer member 11 is stopped at a position where the conductivity material 14 contacts the fixing roller 1.

  In the present embodiment, the heat transfer member 11 is disposed at an obliquely upper position avoiding directly above the heater 3 of the fixing roller 1, which is the highest temperature portion and has a large amount of heat transfer, so that heat is transferred from the heat transfer member to the atmosphere. Can be reduced. Further, when the heat transfer member 11 is stopped, the low thermal conductivity material 14 is stopped so as to come into contact with the fixing roller 1, so that the heat transfer from the fixing roller 1 to the heat transfer member 11 can be made poor. In addition, since the heat transfer member 11 is configured by alternately arranging the high heat conductivity material 13 and the low heat conductivity material 14, heat conduction is suppressed by the low heat conduction portion, and heat is transferred from the contact portion of the fixing roller of the heat transfer member. The heat transfer in the circumferential direction in the conductive member can be suppressed, and as a result, the release of heat from the heat transfer member 11 to the atmosphere can be reduced.

<Example 5>
10A and 10B are diagrams showing a fifth embodiment of the fixing device according to the present invention. FIG. 10A is a diagram showing a control block and a schematic cross section, and FIG. 10B is a front view. In this example, as in the first embodiment, the fixing device includes a fixing roller 1 incorporating a heater 3, a pressure roller 2 that is pressed against the fixing roller 1, and a temperature detection that detects the temperature of the fixing roller 1. A member 4 and a heat transfer member 11 pressed against the surface of the fixing roller 1 are provided. The heater 3 is controlled to have a constant temperature by a temperature control device based on a temperature detected by a temperature detection member 4 (not shown).

  The surface of the fixing roller 1 is covered with a releasable material. The surface of the pressure roller 2 is covered with an elastic material. A nip portion is formed between the fixing roller 1 and the pressure roller 2, and the transfer paper 5 onto which the unfixed toner 6 has been transferred passes through the nip portion. The unfixed toner 6 melts at the nip portion, and is fixed to the transfer paper 5 under pressure.

  In this example, the temperature detection member 4 is disposed at the end of the fixing roller 1 in the longitudinal direction. Further, the heat transfer member 11 is disposed on the upstream side in the rotation direction of the fixing roller 1 with respect to the temperature detection member 4 of the fixing roller 1 and on the downstream side from the nip portion between the fixing roller 1 and the pressure roller 2. The heat transfer member 11 is disposed at a position avoiding the heater 3 directly above the fixing roller 1, that is, obliquely above the heater 3.

  FIG. 11 is a schematic cross-sectional view showing the configuration of the heat transfer member. The heat transfer member 11 is configured by alternately arranging a high thermal conductivity material 13 and a low thermal conductivity material 14 on a resin heat insulating layer 12. In this example, an aluminum-based material is used as the high thermal conductivity material, and an iron-based material is used as the low thermal conductivity material. Further, an aluminum-based material can be used as the high thermal conductivity material, and a heat resistant resin material can be used as the low thermal conductivity material.

  In this example, the fixing roller 1 is rotationally driven by a drive source 41 as shown in FIG. The drive source 41 is driven and controlled by the control means 42. The heat transfer member 11 rotates with the fixing roller 1. Similarly to the fourth embodiment, the control unit 42 is connected to a detection unit 34 that detects the rotational position of the heat transfer member 11. The control unit 33 is driven based on the connection detection result of the detection unit 34. The source 31 is driven.

  The detection means 34 has the same structure as that described with reference to FIG. 9 in the fourth embodiment. That is, the detection means 34 includes a filler 21 that rotates in synchronization with the heat transfer member 11 and includes a slit, and a photosensor 22 that is installed in the vicinity of the filler 21. The detection unit 34 detects the position where the low thermal conductivity material 14 is disposed, and the control unit 42 controls the rotation of the drive source 41 to reduce the low heat of the heat transfer member 11 when the rotation of the fixing roller 1 is stopped. The fixing roller 1 is stopped at a position where the conductivity material 14 contacts the fixing roller 1.

  In the present embodiment, the heat transfer member 11 is disposed at an obliquely upper position avoiding directly above the heater 3 of the fixing roller 1, which is the highest temperature portion and has a large amount of heat transfer, so that heat is transferred from the heat transfer member to the atmosphere. Can be reduced. Further, when the heat transfer member 11 is stopped, the low thermal conductivity material 14 is stopped so as to come into contact with the fixing roller 1, so that the heat transfer from the fixing roller 1 to the heat transfer member 11 can be made poor. In addition, since the fixing roller 1 is configured by alternately arranging the high thermal conductivity material 13 and the low thermal conductivity material 14, the heat conduction is suppressed by the low thermal conduction portion, and the heat conduction from the contact portion of the fixing roller of the heat transfer member. The movement of the heat in the circumferential direction in the member can be suppressed, and as a result, the release of heat from the heat transfer member 11 to the atmosphere can be reduced.

<Example 6>
12A and 12B are views showing a sixth embodiment of the fixing device according to the present invention, in which FIG. 12A is a schematic cross-sectional view, and FIG. 12B is a front view. In this example, as in the first embodiment, the fixing device includes a fixing roller 1 incorporating a heater 3, a pressure roller 2 that is pressed against the fixing roller 1, and a temperature detection that detects the temperature of the fixing roller 1. A member 4 and a heat transfer member 11 pressed against the surface of the fixing roller 1 are provided. The heater 3 is controlled to have a constant temperature by a temperature control device based on a temperature detected by a temperature detection member 4 (not shown).

  The surface of the fixing roller 1 is covered with a releasable material. The surface of the pressure roller 2 is covered with an elastic material. A nip portion is formed between the fixing roller 1 and the pressure roller 2, and the transfer paper 5 onto which the unfixed toner 6 has been transferred passes through the nip portion. The unfixed toner 6 melts at the nip portion, and is fixed to the transfer paper 5 under pressure.

  In this example, the temperature detection member 4 is disposed at the end of the fixing roller 1 in the longitudinal direction. Further, the heat transfer member 11 is disposed on the upstream side in the rotation direction of the fixing roller 1 with respect to the temperature detection member 4 of the fixing roller 1 and on the downstream side from the nip portion between the fixing roller 1 and the pressure roller 2. The heat transfer member 11 is disposed at a position avoiding the heater 3 directly above the fixing roller 1, that is, obliquely above the heater 3.

  FIG. 13 is a schematic cross-sectional view showing the configuration of the heat transfer member, and FIG. 14 is an enlarged cross-sectional view showing the configuration of the heat transfer member. The heat transfer member 11 is configured by alternately arranging a high thermal conductivity material 23 and a low thermal conductivity material 24 on a resin heat insulating layer 12. A hollow air layer 27 is formed in the low thermal conductivity material 24. By forming the air layer 27, the thermal conductivity of the low thermal conductivity material 24 becomes smaller. In this example, an aluminum-based material is used as the high thermal conductivity material, and an iron-based material is used as the low thermal conductivity material. Further, an aluminum-based material can be used as the high thermal conductivity material, and a heat resistant resin material can be used as the low thermal conductivity material.

  In the present embodiment, the heat transfer member 11 is disposed at an obliquely upper position avoiding directly above the heater 3 of the fixing roller 1, which is the highest temperature portion and has a large amount of heat transfer, so that heat is transferred from the heat transfer member to the atmosphere. Can be reduced. Further, since the heat transfer member 11 is configured by alternately arranging the high heat conductivity material 23 and the low heat conductivity material 24 including the air layer 27, the heat conduction is suppressed by the low heat conduction portion, and the fixing roller of the heat transfer member It is possible to suppress the movement of the heat in the circumferential direction in the heat conduction member from the contact portion of the heat transfer member 11, and to reduce the release of heat from the heat transfer member 11 to the atmosphere.

In the present invention, the temperature detection member 4 may be disposed at the center in the longitudinal direction of the fixing roller 1. Further, not only the fixing roller 1 but also the pressure roller 2 or a belt type fixing device can be developed.

1 is a cross-sectional view conceptually showing an image forming apparatus such as an electrophotographic copying machine or printer according to the present invention. 1A and 1B are diagrams illustrating a configuration of a fixing device according to a first embodiment, in which FIG. 1A is a schematic cross-sectional view, and FIG. 6 is a graph showing a temperature distribution of a fixing roller in the fixing device according to the first embodiment in comparison with a conventional fixing roller. 2A and 2B are diagrams illustrating a second embodiment of the fixing device according to the present invention, in which FIG. 3A is a schematic cross-sectional view, and FIG. 4A and 4B are diagrams illustrating a third embodiment of the fixing device according to the present invention, in which FIG. 5A is a schematic cross-sectional view, and FIG. It is a schematic sectional drawing which shows the structure of a heat transfer member. FIG. 8 is a diagram illustrating a fourth embodiment of the fixing device according to the present invention, where (a) is a diagram showing a control block and a schematic cross section, and (b) is a front view. It is a schematic sectional drawing which shows the structure of a heat transfer member. It is a figure which shows the structure of a detection means, (a) is a schematic plan view, (b) is a schematic side view. FIG. 10 is a diagram illustrating a fifth embodiment of the fixing device according to the present invention, where (a) is a diagram illustrating a control block and a schematic cross section, and (b) is a front view. It is a schematic sectional drawing which shows the structure of a heat transfer member. It is a figure which shows the 6th Example of the fixing device which concerns on this invention, (a) is a figure which shows a schematic cross section, (b) is a front view. It is a schematic sectional drawing which shows the structure of a heat transfer member. It is an expanded sectional view showing the composition of a heat transfer member. FIG. 10 is a schematic cross-sectional view showing a conventional fixing device. FIG. 10 is a schematic cross-sectional view showing another conventional fixing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3 Heater 4 Temperature detection member 5 Transfer paper 6 Unfixed toner 7 Heat transfer member 10 Fixing device 11 Heat transfer member 12 Heat insulation layer 13 High thermal conductivity material 14 Low thermal conductivity material 21 Filler 22 Photo sensor 23 High thermal conductivity material 24 Low thermal conductivity material 27 Air layer 31 Drive source 32 Drive source 33 Control means 34 Detection means 41 Drive source 42 Control means 111 Unit 112 Image forming unit 113 Automatic document feeder (ADF)
114 Document discharge trays 115 to 118 Paper feed cassette 119 Paper feed unit 120 Paper discharge tray 121 Document table 122 Pickup roller 123 Document transport belt 124 Contact glass 125 Device 126 Light source 127 Optical system 128 Photoelectric conversion element 130 Photoconductor 131 Charging device 132 Unit 133 Developing device 134 Transfer device 135 Cleaning device 137 Discharge roller pair

Claims (9)

In the fixing device in which the temperature detection member of the fixing roller is disposed at the end portion in the longitudinal direction of the fixing roller and the heat transfer member is disposed in contact with a part of the surface of the fixing roller.
The fixing device according to claim 1, wherein the heat transfer member includes a plurality of members having different thermal conductivities arranged alternately along a circumferential direction on a heat insulating resin heat insulating layer.   The heat transfer member is upstream of the fixing roller rotation direction and downstream of the nip portion between the fixing roller and the pressure roller with respect to the temperature detecting member of the fixing roller, and avoids the heat source of the fixing roller. The fixing device according to claim 1, wherein the fixing device is disposed at a position.   The heat transfer member is disposed on the upstream side of the fixing roller rotation direction with respect to the temperature detection member of the fixing roller and on the downstream side of the nip portion between the fixing roller and the pressure roller and below the fixing roller. The fixing device according to claim 1, wherein:   Driving means for operating the heat transfer member, position detecting means for detecting the rotational position of the heat conducting member, and low temperature of the heat transfer member while controlling the driving means and stopping the rotation of the fixing roller. 4. The fixing device according to claim 1, further comprising a rotation control unit that causes only the conductivity member region to contact the fixing roller.   The heat transfer member is configured to rotate with the fixing roller, and when the position detection means for detecting the rotation position of the heat conducting member and the driving means for the fixing roller are controlled to stop the rotation of the fixing roller, 4. The fixing device according to claim 1, further comprising a rotation control unit configured to control only a low thermal conductivity member region of the heat transfer member to contact the fixing roller. 5.   The fixing device according to claim 1, wherein the plurality of members having different thermal conductivities of the heat conducting member are an aluminum-based material and an iron-based material.   6. The fixing device according to claim 1, wherein the plurality of members having different thermal conductivities of the heat conducting member are an aluminum material and a heat resistant resin material.   8. The fixing device according to claim 6, wherein an air layer is provided inside the iron-based material and the heat-resistant resin material. An image forming apparatus comprising the fixing device according to claim 1.