Toner image fixing device
United States Patent Tomono et al.  
 [ TONER IMAGE FIXING DEVICE [75] Inventors: Makoto Tomono; Ken Nakamura;  
 Niriyoshi Tarumi, all of Tokyo; Masayuki Sato, Otsuki, all of Japan [73] Assignee: Konishiroku Photo Industry Co.,  
 Ltd., Tokyo, Japan [22] Filed: Sept. 7, I973 [2]] App]. No.: 394,972  
 [30] Foreign Application Priority Data Sept. 9, i972 Japan .l 47-89629 [52] US. Cl. 432/60; 432/228; 2l9/469 [51] Int. Cl. 603g 13/20; 603g l5/20 [58] Field of Search 432/59-62, 432/227-228; 29/132; 219/216, 388, 469-47]; 100/93 RP; 226/l90 [56] References Cited UNITED STATES PATENTS 3 29l,466 l2/l966 Aser et ul. 432/60 3,395,636 8/[968 Hess [00/93 RP i 4.2., 5 A r, 29, 1975 3,409,280 ll/l968 Springett 432/60 3.437.032 4/1969 Manghirmalani et almm. 100/93 RP 3.452.18l 6/1969 Stryjewski 432/60 3,595,539 7/l97l Kimura l 432/60 3,637,976 l/l972 Ohta ct 3L.v 2l9/2l6 3,659,347 5/l972 Wallsten 34/l24 Primary Examiner-John .l. Camby Assistant ExaminerHenry C. Yuen Allurney, Agent, or Firm-Bierman &amp; Bierman [57] ABSTRACT 4 Claims, 2 Drawing Figures TONER IMAGE FIXING DEVICE The present invention relates to a toner image fixing device in electrostatic recording. electrostatic printing or electrophotography. More particularly. the present invention relates to the device fixing thermally toner images which has thermally fixing means contacting with a toner image on a support member.  
  A toner image formed by electrostatic method is weak in adhesion to the support and therefore can be easily injured by a mechanical action. so that the toner image is fixed to the support to produce a permanent image.  
  Generally, thermal fixing means are used for the toner image fixing. The thermal fixing devices are devided into two types; one utilizing heat radiation and the other having the heated fixing member contacting with the support carrying toner images. According to the former type fixing device. the toner images are heated and fused by heat radiation to adhere to the support without contacting the toner images with heat source. This device has an advantage that there is nothing contacting the toner images in fixing step, so that the images are not injured at all mechanically, but on the other hand. it has a drawback that since the toner image itself has poor heat-conductivity the fixing speed is low-and also a great heat energy is required.  
  On the other hand, in the latter type of devices where the toner image is contacted with the thermo-fixing member such as a heated roller. Although, it is free from the above defects in the former device utilizing the heat radiation, the toner image or a part thereof may be fused and stick to the themo-fixing member and then, the toner stuck to the member resticks to the support, so that fogs or contaminations arise (hereinafter referred to offset phonomenon&#34;).  
  In order to overcome these defects, it is proposed to coat the surface of the thermo-fixing member with a material such as polytetrafluoroethylene to prevent fused toner from adhesion to the thermo-fixing member (hereinafter referred to offset preventing material), then further apply thereon a releasing agent such as silicon oil, and then heat the portion contacted with the toner image at a sufficient temperature for fuse of the toner.  
  This fixing device utilizing the contact of the thermofixing member and the toner images can considerably alleviate the conventional drawbacks as abovementioned. Use of such thermo-fixing member however, is not sufficient to perfectly eliminate the offset phenomenon. and also the offset preventing material proves poor in fastness to heat particularly when used continuously for a long time, so that only specific resin materials which have relatively a low melting point can be used for the toner. Further. because of poor thermal conductivity of the offset preventing material, a remarkably great heat energy is required, and this makes temperature control difficult.  
  Moreover. due to poor durability of the offset preventing material or difficulty in obtaining uniformity of the surface during manufacture of the device, there would be caused unevenness in contact with the toner image.  
  An object of the present invention is to provide an improved toner fixing device which is free from the above-said defects, in the device having a thermo-fixing member contacting with the image support.  
  According to the present invention, an improved toner image fixing device is provided which comprises a thermo-fixing means contacting with the toner images on a support; said means having a metallic microporous surface and heated to a temperature sufficient to fix the toner image; and releasing agent feeding means for feeding a releasing agent onto the surface.  
  The metallic micro-porous surface of said thermofixing means are ones which are made from a metal or a metal oxide, such as an alumite surface, and formed with a plurality of fine pores of less than I p. in size at a porosity (percentage of the area taken by the pores to the total surface area) of less than about 25%, preferably from 10 to 20%.  
  The thermo-fixing means according to the present invention can be produced by, for instance. polishing the surface of a roller, preferably a metallic roller, and coating the polished surface with an anode-oxidated film of aluminium (alumite working) or by forming a metallic film by metal spray.  
  This process is very easy to perform and if a roller with the polished surface is used as base, no polishing is required after working and the desired articles with uniform thickness can be obtained with ease. On the other hand, in the prior art thermo-fixing means, it is to be noted that when working an offset preventing material, final polishing of the surface of the offset preventing material layer is indispensable and it is also difficult to obtain uniform polishing due to the characteristics of the offset preventing material.  
  Also, in the present invention the portion of the thermo-fixing means contacted with the toner is heated to a temperature sufficient to allow fusion and adhesion of the toner to the support. This temperature, although somewhat varied depending on the kind of toner material used and the type of the toner image on a support, is usually from about to 230C, preferably from about to C, in the case of paper support.  
  The toner-contacted portion of the thermo-fixing means are coated with releasing agent such as silicon oil, and such portion is also heated to a temperature such as defined above and contacted with the toner images retained on the support, whereby very excellent fixing effect as well as offset preventing effect can be obtained. This is considered due to the fact that the releasing agent penetrates into the fine pores and are retained therein.  
  Further, as this thermo-fixing means have a metallic surface, it has good heat conductivity and is also excellent in durability and fastness to heat. Now, the present invention is described in further detail with reference to the accompanying drawings. However. it should be obvious that various modifications can be made within the scope of the invention.  
  FIG. 1 shows an embodiment of the present invention.  
  FIG. 2 shows another embodiment of the present invention.  
  Referring first to FIG. 1. reference numeral 1 designates a support such as a paper sheet which carries thereon the toner images 2 and which is moved for wardly to let the toner images 2 contact with a thermofixing means 3.  
  Numerals 5 and 5 indicate the guide members adapted to help feeding and discharging, respectively, of the support 1 to and from the fixing device. Said guide member 5 is arranged such that a passage for inserting the support 1 and the toner images 2 carried thereon will be formed between the thermo-fixing element 3 and a roller 6 which is positioned to be pressed against the roller 4.  
  The thermo-fixing means 3 consist of a hollow metal roller 4 and a metallic layer 7 having a microporous metallic surface Preferably, the thermo fixing means are composed of an aluminum roller 4 and an alumite layer 7.  
  ln the inside of said roller 4 is disposed a heater 8, and the surface of the metallic layer 7 is applied with releasing agent 12 such as silicon oil supplied form a releasing agent feeder means 11.  
  The releasing agent feeder means 11 consist of a roller l3 immersed in a releasing agent 12, releasing agent permeable material 9 contacted with said roller, and a supporting member 10 for said material 9.  
  The releasing agent is supplied uniformly to the surface of the metallic layer 7 through the rotating roller 13 and said material 9. It is desirable that the roller 6 has the fixing effect and sufficient elasticity and non-adsorbability to the releasing agent as well as excellent durability and fastness to head. This roller 6 is at least required to be pressedly contacted with the thermo-fixing means during the fixing operation, so that it is desirable that such roller is made of an elastic material such as silicon rubber or coated on its surface with a flexible material such as polytetrafluorethylene. In operation of the present toner image fixing device having the described arrangements, when the support 1 carrying the toner images thereon is inserted between the thermo-fixing means 3 and the roller 6 and the toner images are contacted with the surface of the metallic layer 7 of said therrno-fixing means 3 heated by the heat source 8 retaining the releasing agent supplied from the feeder means 11, and with rotation of said thermo-fixing means 3 and roller 6 the toner images are uniformly fused and fixed to the support.  
  If an aluminium roller is used as the roller 4 f the thermo-fixing means 3 and an alumite layer as the metallic layer 7, very excellent heat conductivity is obtained.  
  Also, thickness of the alumite layer can be easily controlled according to the conditions of manufacture. In the present case, good results can be obtained by controlling such layer thickness within the range of about to 5012.  
  FIG. 2 is a diagrammatic illustration of a fixing device according to another embodiment of the present invention.  
  In this embodiment, the support 21 carrying the toner images 22 thereon is placed on a belt 24 which is passed round a roller 25 and another roller, not shown, provided in opposed relation to said roller 25. The belt 24 is pressedly contacted with the thermofixing means 23 at the position of the elastic roller 25, and the support 21 is carried to this position by said belt.  
  The thermo-fixing means 23 consist of a hollow roller 26 and a metallic layer 27 formed thereon by metal spray method. In the surface of said metallic layer 27 are formed a plurality of small pores, and a heater 28 is provided in the hollow of said roller 26. The surface of the metallic layer 27 on said thermo-fixing means 23 are contacted at a suitable location with the releasing agent permeable material 30 on the surface of a roller 29. The roller 29 coated with the releasing agent permeable material 30 constitutes a releasing agent feeding mechanism with another roller 31 which is immersed in the releasing agent. Thus, when said roller 31 rotates, the releasing agent is supplied to the material 30 which is contacted with said roller 31, and as the roller 29 rotates, the releasing agent is further conveyed to the surface of the metallic layer 27.  
  According to this fixing device, the support 21 is inserted into between the thermo-fixing means 23 and the belt 24 with rotation of the roller 25 and is heated to a pertinent surface temperature by the heater, and as the toner images are fused and fixed to the support 21.  
  FIGS. 1 and 2 merely illustrate the embodiments of the present invention which can be embodied in vari ous other forms. For example, the releasing agent feeder means may not necessarily be arranged such as to continuously supply the parting agent, but may be arranged to supply the releasing agent only when so required. This is possible because the thermo fixing means according to the present invention has very excellent releasing agent retainability may to be more concrete one arrangement be made such that the roller 13 or 29 or 31 will be rotated only when feeding of releasing agent is required, or that the thermo-fixing means will be contacted with said material 9 or 29 only when it is necessary to do so.  
  Also, the releasing agent feeding means may be contituted from a belt and roller for sustaining the belt.  
  For instance, a belt made from a releasing agent permeable material may be passed round the roller 29 or FIG. 2.  
  It is also possible to make arrangement such that the thermo-fixing means and the roller 6 or belt 24 will be press-contacted with each other synchronously with insertion of the support which carries the toner images thereon. This arrangement can improve durability of the roller 6 or belt 24.  
  Further, in for example the embodiment of FIG. 1, if the roller 4 is formed from a micro-porous metallic roller, it is possible, in some cases, to supply the releasing agent from the inside. Also, heating of the thermofixing means may be accomplished not internally but through contact with a heated roller.  
  According to the above-described toner image fixing device of the present invention, no transfer of toner images to the thermo-fixing means is made and also said means have excellent durability fastness to heat, so that uniform and good fixing can be practiced and also durability of the apparatus is appreciably improved. Still further, the present device retains all of the advantages obtainable from use the conventional thermo-fixing means and hence is of extremely high practical utility.  
  If merely a metal roller is used as the thermo-fixing means it is impossible to prevent offset phenomenon of the toner images and also fixing becomes uneven to deteriorate the image characteristics.  
 What is claimed is:  
  1. A device for fixing a toner image to a support member bearing said toner image thereon, comprising: thermo-fixing means having a metallic micro-porous surface and being heated to a temperature sufficient to fix the toner image to the support member, said metallic micro-porous surface having a plurality of fine pores less than 1 micron in size and a porosity of less than 25%; and releasing agent feeding means for feeding a wherein said releasing agent feeding means comprising material which permeate the releasing agent.  
  4. A toner image fixing device according to claim 1 wherein said releasing agent feeding means are a rotating roller which contacts with said thermo-fixing means and on which a releasing agent is coated.  
 * t l l