Recording apparatus

The present invention provides an apparatus wherein image fixing means is controlled for different fixing conditions under which a toner image is fixed on a recording material to adapt it to a synthetic resin sheet as the recording material or to a color image to be fixed, including at least one of fixing temperature, fixing speed and actuation of cleaning means. The present invention is particularly effective in use for a recording system in which the fixing temperature and speed are decreased and the cleaning means is actuated when a color image is to be formed on a transparent or resin sheet. The present invention is most useful for a color image recording system.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an apparatus for fixing and recording 
toner images on various different recording materials. The present 
invention is particularly advantageous upon recording colored images, and 
can be applied to all of the types of image forming and recording systems 
which have currently been utilized, such as copying machines, laser 
printers, printing machines, facsimiles and others. 
2. Description of the Prior Art 
The prior art includes Japanese Patent Publication No. 51-10490 in which 
toner images are fixed to recording materials taking account of the 
thickness or color thereof, and Japanese Laid-open Patent Application Nos. 
51-78342 and 52-20841 in which attention is paid to the color of toner 
images. 
Of these Publications, Japanese Patent Publication No. 51-10490 discloses 
controlling temperature of fixation so that it is increased as the 
thickness of recording materials increases. Such a method can follow the 
different thickness of the recording materials but not the kind of toner 
images to be fixed on recording materials and the property of the 
recording materials. In addition, if the temperature of fixation is simply 
changed, there is produced an "offset" phenomenon in which a toner image 
is undesirably transferred onto the surface of a contact heating type 
fixing roller that is recently being utilized wide in the art. 
On the contrary, Japanese Laid-open Patent Application Nos. 51-78342 and 
52-20841 disclose a technical concept in which paper with an increased 
thickness is more slowly moved under a radiantly heating lamp of 
non-contact fixture type when a multicolor toner image is formed thereon 
in comparison with case where a single-color toner image is formed on 
paper with a reduced thickness in a color copying machine. However, they 
are irrelevant to a problem with respect to offset, which will be 
described hereinafter, since the non-contact type lamp is used therein, 
and have no teaching as to how to meet the property change and state 
change of the recording material. In addition, the temperature of fixation 
is maintained constant in either of the monochromatic or multi-color toner 
image. 
It has also been proposed that the speed of recording paper at which it is 
being moved between a pair of fixing rollers is changed depending upon the 
thickness of that recording paper at a constant temperature. However, such 
a proposal has no variable control to meet variations in recording 
material and/or colored toner image, and no temperature control. 
Under such a state and tendency of art, the present invention is directed 
to a recording system which can satisfactorily overcome various problems 
in the prior art, which will be described below. 
First of all, the technical background concerning the present invention 
will first be described. The modern recording systems can utilize plain 
paper of various different types, such as thick paper, thin paper, postal 
or post cards and others. It is also strongly demanded to use synthetic 
resin films which is used in over-head projectors (hereinafter called 
simply "OHP"). In the prior art, toner images could only temporarily be 
fixed on the synthetic resin films for some period of time. And, the 
resulting images were rather easily be damaged and were not the faithfully 
reproduced images. Namely, the prior art systems does not provide a 
satisfactory formation of fixed images on the synthetic resin films with 
respect to fixation and sharpness. 
The modern recording systems can provide both multi-color and monochromatic 
images, the monochromatic images being obtained with different colors 
respectively. In such a recording system that multicolor and monochromatic 
modes can selectively be changed from one to another, the fixation of 
multicolor images is inferior to that of monochromatic images. Therefore, 
"offset" toner will be increased in amount in the multi-color mode. This 
adversely affects the fixation of monochromatic image fixation and 
additionally highly decrease the ability of a rotatable fixing member 
which contacts the toner images for fixation. Consequently, the rotatable 
fixation member must frequently be exchanged. 
When images are to be recorded on synthetic resin films, the above problem 
with respect to the rotatable fixation member contacting the toner images 
cannot be avoided because of the decreased ability of fixation and more 
offset toner. It is substantially impossible to record colored toner 
images, particularly on transparent film of synthetic resin, which is more 
strongly required in the art. There are many newly created problems 
relating to sharpness, fixation and offset. 
One of the newly created problems is that a greater amount of a toner image 
is transferred to a rotatable member such as a fixing roller, fixing belt 
or the like, which is used to fix the toner images onto synthetic resin 
film. In such a case, the rotatable member immediately becomes 
inoperative. Another problem is that the colored toner images are so 
unsatisfactorily fixed on the synthetic resin film that the resulting 
images are rather highly different from the original in color tone. 
The problem of color tone associated with the formation of images on 
synthetic resin films will now be described. 
Even if a color image is heatedly fixed on a synthetic resin film as in the 
prior art fixation of color image, the fixed image will have no 
practicable color tone when it is projected onto a screen through the OHP. 
For example, the projected image of yellow-colored toner becomes dark as a 
whole with the half-tone portion thereof being gray-colored. The projected 
images of cyan- and magenta-colored toners also become dark as a whole 
with the color tones being shifted into light green- and red-colors, 
respectively. This is not practicable. 
SUMMARY OF THE INVENTION 
It is a primary object of the present invention to extend the service life 
of a rotatable member for fixing toner images. 
Another object of the present invention is to improve the fixation of toner 
images to synthetic resin films. 
Still another object of the present invention is to improve the service 
life of a rotatable fixing member with respect to the synthetic resin 
films or color images. 
A further object of the present invention is to provide a recording 
apparatus which can improve the fixation and greatly decrease the amount 
of offset toner independently of the types of recording material. 
A further object of the present invention is to provide a recording 
apparatus which can form multicolor images on the synthetic resin films. 
A further object of the present invention is to provide a recording 
apparatus which can properly and positively form multi-color images on the 
synthetic resin films, which can decrease the amount of offset toner 
transferred to a rotatable fixing member, and which can highly improve the 
service life of the rotatable fixing member. 
These and other objects, features and advantages of the present invention 
will become more apparent upon a consideration of the following 
description of the preferred embodiment of the present invention taken in 
conjunction with the accompanying drawings. 
The inventors have thought that the improved color tone of projected images 
on the screen can be obtained by sufficiently fusing the toner to increase 
the adhesiveness between the toner particle surfaces to provide a toner 
layer having uniform thickness and density as well as smooth surface and 
to minimize the air cavities. 
The present invention is therefore aimed at a recording apparatus which can 
greatly improve the service life of a rotatable member such as a roller or 
belt which is used in fixation and which can increase the ability of 
fixation of images, particularly color images to synthetic resin films. 
It is thought that undesirable phenomena with OHP images may result from 
the deflection and scattering of light created when the projecting light 
travels through the toner layer, and this is caused by, for example, the 
color toner being fixed on the film under a hemi-melting state to provide 
air cavities in the toner layer or by the surface of the toner layer being 
rough.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1, there is shown an electrophotographic type color 
copying system which comprises an electrophotographic type photosensitive 
drum 1 having an insulation surface layer and rotatably supported by a 
shaft 2. Receiving a copy instruction, the drum 1 begins to rotate in the 
direction of arrow 3. When the drum 1 is rotated to a predetermined 
position, an original O placed on a platen 4 of transparent glass is 
illuminated by an illuminating lamp 6 formed integrally with a first 
scanning mirror 5 with the reflected light therefrom being reflected by a 
second scanning mirror 7. The first and second scanning mirrors 5 and 7 
are together moved at a speed ratio of 1:1/2 so that the optical path 
length between the original O and a lens 8 will be maintained constant 
while scanning the original O. The reflected light image is directed 
through the lens 8 and a third mirror 9 to a color separation filter 10 
whereat it is subjected to color separation. The light is then imaged on 
the drum 1 through a fourth mirror 11 and a dustproof glass 12 at an 
exposure station 13. 
The drum 1 is electrically discharged by a charge remover 14 and then 
charged to positive polarity by a primary charger 15. The drum 1 is 
thereafter exposed through a slit to the image light which has been 
provided by the illuminating lamp 6 and so on at the exposure station 13. 
Simultaneously, the drum is electrically discharged by a discharger of AC 
or having the opposite polarity component (for example, negative) to the 
polarity of the primary charger 15 by a charge remover 16. Subsequently, 
the drum 1 is subjected to a whole surface exposure by a whole surface 
exposure lamp 17 such that an electrostatic latent image having a high 
contrast is formed on the drum 1. 
The electrostatic latent image on the photosensitive drum 1 is then 
visualized into a toner image by a developing device 18. The developing 
device 18 includes four developing units of yellow 181, magenta 182, cyan 
183 and black 184 one of which is selected in response to the color 
separation filter used on exposure to obtain a toner image having the 
desired color (single-color, multi-color or full-color). 
A cassette 191 contains recording materials 201 which are supplied one at a 
time to the machine by means of a feed roller 211. The supplied recording 
material is timed roughly by first registration rollers 22 and then 
precisely timed by second registration roller 23, and the leading edge of 
the recording material is grasped by a gripper 24 on a transfer drum 29 
which will be described hereinafter in detail. As the transfer drum 29 is 
being rotated, the recording material 201 is wound and conveyed around the 
transfer drum 29. As the recording material 201 is moved between a 
transfer charger 25 on the transfer drum 29 and the photosensitive drum 1, 
the toner image is transferred from the photosensitive drum 1 onto the 
recording material 201. The transfer drum 29 rotates through a desired 
number of complete revolutions while grasping the leading edge of the 
recording material 201 at the gripper 24. Thus, the desired number of 
color images are transferred onto the same recording material. 
It is noted that the illustrated copying machine comprises two cassettes 
which contain recording materials of different sizes and is adapted to 
supply recording materials of one of the sizes which is selected in 
response to instructions. 
Upon completion of the transfer step, the recording material 201 is 
released from the gripper 24 and conducted onto a conveyor belt 27 by 
means of a separation pawl 26. The recording material is then conveyed 
into the nip between fixing rollers 31 and 34 used as thermally fixing 
rotatable means which at the toner image is fixed to the recording 
material. Finally, the recording material having the fixed image thereon 
is discharged into a tray 30. After the transfer step, the photosensitive 
drum 1 is cleaned at its surface by means of a cleaner 28 including a 
resilient blade, and then ready for the next cycle. 
FIG. 2 shows the detailed construction of the fixing means A including the 
fixing rollers 31 and 34 and associated control blocks. 
One of the fixing rollers 31 is in the form of a metallic pipe 32 which is 
covered by a layer 33 of RTV silicone rubber throughout the peripheral 
surface thereof. The fixing roller 31 is engaged and heated by a roller 
38. The other fixing roller 34 includes a metallic pipe 35 and a layer 36 
of synthetic resin such as Teflon (trade mark of Du Pont) covering the 
peripheral surface of the pipe and including a infrared lamp type heater 
37 disposed therein. These thermally-fixing rollers 31 and 34 serves to 
cause the recording material to be subjected to the fixing process. 
The roller 38 engaging the roller 31 under pressure includes a metallic 
pipe 39 and a layer 40 of synthetic resin such as tetrafluoroethylene 
covering the metallic pipe 39 and including an infrared lamp type heater 
41 located therein, as in the roller 34. 
A container 42 containing silicone oil 43, which is dipped out and applied 
to the surface of the roller 38 by an application felt 44. The silicone 
oil is then transferred from the surface of the roller 38 to the surface 
of the roller 31. 
The application felt 44 is supported, together with a holding plate 45, by 
a rotating shaft 46. An actuator 451 consisting of an electromagnetic 
plunger and a tension spring, not shown, is provided to displace the 
application felt 44 between an application position in which the felt 44 
contacts the roller 38 and a non-application position in which the felt 44 
is spaced away from the roller 38. 
A cleaning web 47 is provided to remove the "offset" toner from the surface 
of the roller 31 and so arranged that the web 47 is pressed against the 
roller 31 by a pressing rubber roller 481 which is adapted to move in the 
direction of arrow only when an image is to be fixed to a synthetic resin 
film for OHP or when a colored toner image is to be fixed to any recording 
material as will be described hereinafter. The cleaning web 47 is taken up 
around a take-up roller 48 while cleaning the surface of the roller 31 
when the take-up roller 48 is driven by drive means 481. A cleaning felt 
roller 49 is also provided to remove the offset toner from the surface of 
the roller 38, which toner has been transferred from the roller 31 to the 
roller 38. The cleaning felt roller 49 is moved to engage the roller 38 by 
an actuator 491 when the rollers 31, 34 and 38 are positioned into 
pressure engagement with one another upon turn-on of a main switch. The 
cleaning web 47 may intermittently be driven. 
The thermally-fixing rollers 33 and 34 are controlled by any known 
temperature control means such that the surface of the roller 34 opposite 
to the surface to which a toner image T is to be fixed has a temperature 
higher than that of the surface of the roller 33 which is adapted to 
contact the toner image T. In the illustrated embodiment, the heater 41 is 
controlled by non-contact type temperature detection means 541 located 
near the surface of the thermally-fixing roller 33 while the heater 37 is 
controlled by detection means 54 which will be described hereinafter. 
The rollers 38 and 49 function to clean the surface of the fixing roller 
31, and the roller 38 functions to heat the roller 31, as well. 
The control system shown in FIG. 2 comprises recording material detection 
means 50 for detecting the sort of the recording material 201, whether it 
is paper or resin sheet or whether it is thick or thin. The detection 
means 50 may automatically or manually be actuated to generate a signal S 
indicative of the instruction or detection of a synthetic resin film for 
OHP. The signal S is then supplied to the actuator 47 which is in turn 
operated to drive the cleaning web 47 in the manner described above. 
When cleaning means such as the cleaning web 47 is auxiliary operated 
against the fixing roller 31 on fixation of the toner image to the 
synthetic resin film, the service life of the fixing roller 31 can greatly 
be extended. Otherwise, a localized heat reduction on the fixing roller 33 
and the transfer of more offset toner to the roller 33 would be produced 
since the offset toner has passed through the roller 38 which is effective 
to clean the fixing roller 33 during the normal fixation. As described 
hereinbefore, this is much influenced by the difficulty of the fixation of 
the toner image to the synthetic resin film. 
In addition to such a problem, if the surface material of the fixing roller 
33 is rubber material, the offset toner penetrates into the rubber 
material. This promotes the offset of the toner into the fixing roller 
surface and extremely reduce the service life of the fixing roller 33. If 
the auxiliary cleaning means is used with the synthetic resin film as in 
the illustrated embodiment, however, the service life of the roller 33 can 
be extended. Since the cleaning means is used in association with the 
synthetic resin films not with plain paper, the cleaning means also can be 
improved in service life. 
In the illustrated embodiment, the above cleaning means is auxiliary 
operated also when a color image (multi-color or full-color) is to be 
fixed to the recording material in addition to the synthetic resin film 
used. This is adopted to overcome such a problem that the offset toner 
strongly adheres to the surface of the fixing roller upon fixation of the 
colored toner image because it is generally obtained from plural different 
kinds of toners which are stacked one over another or mixed one with 
another. The cleaning means is used only for the fixation of color images 
rather than single-color images for such a purpose that the service life 
of the cleaning means can be extended. 
These problems becomes particularly remarkable when a color image is to be 
formed on a synthetic resin film, since the amount of the offset toner is 
added in combination. Therefore, the auxiliary cleaning means is extremely 
important in that the service life of the roller 33 can be extended. 
The control system also comprises selector means 51 adapted to change the 
temperature T of the fixing roller set by temperature control means 52, 
which will be described hereinafter, and the speed V of the fixing roller 
set by drive control means 53 which will also be described hereinafter, 
depending on the sort of a selected recording material. The temperature 
and speed of the fixing roller are simultaneously increased or decreased 
together by the selector means 51. Thus, the ability of fixation suitable 
for the selected recording material can be provided by setting the 
temperature and speed of the fixing roller by the selector means 51. 
In the illustrated embodiment, the temperature control means 52 comprises 
surface temperature detecting means 54 located in engagement with or near 
the surface of the roller 34, and power supply means 55 for controlling 
the electric power to the heaters 37 and 41 with respect to voltage or 
current. The drive control means 53 comprises drive supply means 56 
including a drive motor, reduction gears, clutches and others which can 
control the speed of the roller 34 directly or indirectly through the 
rollers 38 and 31. 
If a recording material is supplied to the above apparatus in the above 
arrangement, a toner image of multi- or full-color will be formed on the 
recording material and then conveyed to the fixing device A shown in FIG. 
2. 
If this recording material is a sheet of ordinary thin paper which is 
normally frequently used, the thermally-fixing roller 34 is controlled to 
have a setting temperature T.sub.0 and a setting speed V.sub.0 such that a 
color image is more strongly be fixed to the recording material with an 
increased sharpness. If the recording material is in the form of a 
synthetic resin film for OHP, which will be called also as transparent 
material, the roller 34 will be controlled to have a setting temperature 
T.sub.2 (&lt;T.sub.0) and a setting speed V.sub.2 (&lt;V.sub.0) such that a 
color image having its increased sharpness and fixation will be obtained 
with the light transmitting therethrough being very bright. If the 
recording material is a sheet of thick paper, the fixing roller 34 is 
controlled to have a setting temperature T.sub.1 (&lt;T.sub.0) and a setting 
speed V.sub.1 (&lt;V.sub.0) as in the transparent material. This also 
provides a color image having its increased sharpness and fixation. 
By selecting the setting temperature and speed, color images which are 
superior in fixation and brightness and have a reduced offset amount were 
obtained for the respective recording materials. Also, the service life of 
the fixing roller was greatly extended. 
FIG. 3 shows manual type recording material detection means for detecting 
the sort of the recording material while FIG. 1 shows automatic detection 
means 66 for discriminating whether or not the recording material is 
transparent, depending on the transmittance at the recording material. In 
any event, there is provided manual or automatic means which generates a 
signal indicative of the sort of a selected recording material. 
The manual type operation section shown in FIG. 3 comprises a key 511 for 
instructing the use of a thick recording material, a key 512 for 
instructing the use of a transparent recording material, and a key 513 for 
instructing the use of ordinary paper which is normally in its depressed 
position. The keys 511, 512 and 513 respectively correspond to the setting 
speeds and temperatures programmed in the selector 51 as described 
previously. The key 511 corresponds to the setting speed and temperature 
V.sub.1, T.sub.1 ; the key 512 to the setting speed and temperature 
V.sub.2, T.sub.2 ; and the key 513 to the setting speed and temperature 
V.sub.0 (&gt;V.sub.1, V.sub.2), T.sub.0 (&gt;T.sub.1, T.sub.2). If the key 513, 
for example, is turned on, thus, the speed and temperature of the 
rotatable fixing means will manually be set to "V.sub.0 " and "T.sub.0 ", 
respectively. 
There is also provided a key 59 for setting the number of copies to be 
continuously reproduced with this number being indicated in a display 60. 
The start of the system is effected by operating a copy key 61. The upper 
and lower cassettes shown in FIG. 1 are selected by operating keys 61 and 
65, respectively. The size of recording materials contained within the 
selected cassette is indicated in a display 58. 
There is further provided a manual operating board 62 for instructing the 
color of an image to be copied and which has mono-color keys for selecting 
developers of different colors, and multi-color and full-color keys 621, 
622 for selecting the combination of the above colors. By selecting one of 
these keys, one can determine the desired color degree of an image (the 
original itself is colored on full-color). 
Since the system is so constructed that proper setting speed and 
temperature can be selected depending on the sort of a recording material 
to which a toner image is to be fixed, problems with respect to reduced 
fixation and remarkable offset can be overcome. In other words, the 
ability of fixation can properly be improved to prevent the offset of 
developers independently of the sort of a recording material to be used. 
Consequently, the service life of the rotatable means for fixing the toner 
image can greatly be improved. Furthermore, the entire operation of the 
system can be improved by using the auxiliary cleaning means for the 
fixing roller when the synthetic resin film tending to create the offset 
is used. 
Particularly, when a transparent recording material is used in the 
full-color mode, the fixation is improved while greatly reducing the 
offset with sufficient amount and time of heating being positively 
provided. Thus, the toner particles are sufficiently fused and bonded with 
one another to provide a uniformalized toner image through which light can 
uniformly pass toward a predetermined position without scattering. An 
image fixed to the transparent recording material in the full-color mode 
had a bright color properly reproduced. 
Further, the advantages of this embodiment will now be described with 
reference to actual numerical value. 
The system shown in FIG. 2 had the rollers 34 and 38 each having a diameter 
of 50 mm and a surface layer 36 or 40 of 25.mu. thickness, and the roller 
31 having a diameter of 60 mm and its rubber layer 33 of 5.5 mm thickness. 
Each of the rollers 34 and 38 had a halogen lamp of 800 W contained 
therein. 
For ordinary thin paper currently used as recording materials, the setting 
surface temperature of the roller 34 was 150.degree. C. and the 
temperature of the roller 31 was 145.degree. C. with the peripheral speed 
of each of the rollers being set at the same speed as in the process 
speed, 150 mm/sec. when toner images were fixed to the recording materials 
in the full-color mode. There were obtained fixed images each having a 
bright color and an appropriate brilliance. There was also no curling in 
the recording materials. 
For synthetic resin OHP films, the surface of the roller 34 had a setting 
temperature of 135.degree. C., the surface of the roller 31 had a setting 
temperature of 140.degree. C. and the peripheral speed of each of the 
rollers 31, 34 was set at 30 mm/sec. which was substantially later than 
the process speed, in full-color mode. 
Each film was held by the gripper 24 on the transfer drum 29 and then wound 
around the transfer drum. After the transfer drum had been rotated through 
a predetermined number of revolutions to transfer a predetermined number 
of images to the film, the latter was released from the gripper 24 and 
conducted onto the conveyor belt 27 by the separation pawl 26. At this 
time, the synthetic resin film was detected by the transmissive light 
detection means 55 including a light source and a light receiving element. 
The detection means 55 then generated a signal which is in turn supplied 
to actuate the separation pawl 26. Simultaneously, the peripheral speed of 
each of the rollers 31 and 34 in the fixing system A was changed to 30 
mm/sec. through an electrostatic clutch and gear mechanism (not shown). If 
the fixing system A has received the signal from the detection means 55 or 
a signal previously supplied manually thereto which is indicative of a 
synthetic resin film, the rollers 34 and 31 was controlled to be 
135.degree. C. and 140.degree. C., respectively. Thus, the film was 
conveyed through the fixing system at a relatively low speed and then 
discharged into the tray 27. 
Thus, the resulting images fixed to the synthetic resin film indicated 
bright colors when projected. 
When images was experimentally fixed to an ordinary paper under the same 
conditions as abovedescribed for the OHP film, the resulting images had no 
bright color with increased offset, increased luster and increased 
curling. Further, the parting material surface of the roller 31 functioned 
satisfactorily only for 9,000 sheets which is about one-half the 
satisfactory number of sheets when the conditions are set for the ordinary 
paper as described above. 
On the contrary, when the synthetic resin materials were used under the 
same conditions as in the ordinary paper, the fixing roller 31 could not 
effect several fixations for the film. Additionally, when the cleaning web 
47 is not used either, the fixing roller 31 was usable for only one 
fixation. When the cleaning web 47 was used under the same conditions, 
only ten film could be fixed. When the cleaning web 47 was used under the 
conditions, described above, for synthetic resin film, full-color images 
could be formed on several thousands of films. 
The inventors carried out the following tests. 
When polyester films of 100 .mu.m thickness and sheets of ordinary paper of 
80 g/m.sup.2 are used in the above-mentioned fixing system, the following 
tables show hot-offset-points obtained as the thermally fixing roller 31 
is changed into various setting temperatures and peripheral speeds (the 
"hot-offset-point", which will be called "H.O.T." hereinafter, indicates 
the surface temperature of the thermally-fixing roller when a toner image 
begins to be transferred from the recording material to the parting 
material surface of the roller as the temperature is gradually increased 
on the thermally-fixing roller), the surface temperature of the 
thermally-fixing roller when desired full-color images are obtained for 
the OHP films (when projected) and for the ordinary paper (hereinafter 
called "S.T."), and cold-offset-points of the thermally-fixing roller (the 
"cold-offset-point" which will be called "C.O.T." indicates the surface 
temperature of the thermally fixing roller when non-fused toner will be 
offset to the roller as the surface temperature of the thermally fixing 
roller is gradually decreased). 
TABLE 1 
______________________________________ 
OHP film 
150 mm/sec. 90 mm/sec. 
30 mm/sec. 
______________________________________ 
H.O.T. 170.degree. C. 
165.degree. C. 
155.degree. C. 
S.T. 160.degree. C. 
153.degree. C. 
135.degree. C. 
C.O.T. 145.degree. C. 
130.degree. C. 
108.degree. C. 
______________________________________ 
TABLE 2 
______________________________________ 
Ordinary paper 
150 mm/sec. -- 30 mm/sec. 
______________________________________ 
H.O.T. 165.degree. C. -- 148.degree. C. 
S.T. 148.degree. C. -- 125.degree. C. 
C.O.T. 135.degree. C. -- 103.degree. C. 
______________________________________ 
Data in the Tables 1 and 2 is plotted to form a graph shown in FIG. 4. In 
FIG. 4, the axis of abscissas indicates peripheral speeds of the thermally 
fixing roller while the axis of ordinates shows the surface temperatures 
of the thermally fixing roller 34. 
From the above tables and FIG. 4, it is understood that the differences 
between H.O.T. and S.T. in the OHP films are 10.degree. C. at 150 mm/sec. 
and 20.degree. C. at 30 mm/sec. These differences are larger than the 
difference between H.O.T. and S.T. in the ordinary paper which is equal to 
17.degree. C. 
In the Table 2, the data for the setting speed of 30 mm/sec. is indicated, 
but the recording materials could not actually be used due to curling. 
Tests were carried out for durability in the fixing roller. 
Under the fixing condition for ordinary paper, that is, such a condition 
that the thermally-fixing roller has its peripheral speed of 150 mm/sec. 
and its surface temperature of 148.degree. C., images were continuously 
fixed on OHP films. These images were full-color images having three 
colors; cyan, magenta and yellow. When 1200 films were used, there was an 
offset phenomenon which provided undesirable copy images. 
Continuous fixation of OHP films was similarly carried out in accordance 
with the present invention under such a condition that the thermally 
fixing roller had a peripheral speed of 30 mm/sec. and a surface 
temperature of 135.degree. C. After 3000 sheets had been used, no offset 
was found. When the resulting images were projected through OHP, there 
were obtained improved chroma and brightness and yet substantially the 
same hue as when a colored toner image was observed in the film placed on 
white paper under reflection. The clear hue was the one not obtained under 
the fixing condition for the above recording materials. The resulting 
color tone was substantially the same as that obtained when the 
thermally-fixing roller had a peripheral speed of 30 mm/sec. and a surface 
temperature of 148.degree. C. 
Thus, the present invention provides a color image forming system which can 
properly carry out the fixation with respect to each of the OHP film and 
ordinary paper. When the fixation is particularly effected for the OHP 
film, bright color can be obtained while improving the parting material of 
the thermally-fixing roller in durability. 
As seen from the foregoing, the present invention can select the setting 
temperature and speed of the rotatable fixing means such as roller or belt 
which are together increased or decreased depending on the sort of the 
recording materials. Thus, toner images can positively and properly be 
fixed to any kind of recording materials with the greatly reduced offset. 
When the present invention is applied to a color recording apparatus, 
superior advantages can be obtained for any kind of recording materials 
including ordinary paper and synthetic film as aforementioned 
Although the previously described embodiment has been described as a 
rotatable fixing member which is in the form of the roller 34 remote from 
the toner image. This is advantageous since the amount of heat for the 
recording materials can stably be obtained independently of the ambient 
atmosphere. The roller 34 may be replaced by a rotatable member directly 
contacting the toner image, for example, the roller 31. 
As described in connection with FIG. 3, the conventional color recording 
system forms images in two roughly classified modes, when the entire image 
is monochromatic (one of black, red, blue or yellow) and when a image has 
the combination of two (multi-color) or three (full-color) of the those. 
As described in connection with the auxiliary cleaning means, the offset 
may highly be created in the multi- and full-color modes rather than the 
monochromatic mode. 
It is preferred that signals corresponding to only the multi- and 
full-colors are created to actuate the cleaning means as in the 
full-colors fixation of said synthetic resin film, described above. This 
is depicted by a block 63 in FIG. 3. If the offset of toner is created 
even by actuating the cleaning means, the latter would move violently be 
worn and have to be frequently replaced with the cleaning effect being 
reduced. Therefore, the fixation should be improved. For this purpose, it 
is preferable to rotatable the fixing roller at a speed lower than that of 
the monochromatic mode when the fixing roller is used for the fixation of 
color image or to reduce the temperature of the fixing roller in addition 
to the lower speed. More particularly, in FIG. 2, there is provided color 
detection means 67 for detecting the formation of color images when the 
multi- and full-color keys 621, 622 are turned on. When the color 
detection means 67 generates a signal C upon detection of the formation of 
a color image, the signal C is used to actuate the actuator 57 for moving 
the cleaning means 47 against the roller, to energize the drive control 
means 53 in addition to the energization of the actuator 57 to decrease 
the peripheral speed of the rollers 31 and 34 into a speed V.sub.2 ' 
smaller than the monochromatic reproduction speed V.sub.0 ', or to 
energize the temperature control means 52 in addition to the energization 
of the actuator and drive control means 57, 53 to set the temperature of 
the rollers 31 and 34 at a temperature T.sub.2 ' lower than that T.sub.0 ' 
of the monochromatic mode. 
It is preferred that the speed and temperature V.sub.2 ', T.sub.2 ' are 
changed into such speed and temperature V.sub.2, T.sub.2 as in the 
previous embodiment, which are used to fix a full-color image to a 
synthetic resin film when the transparent key 512 is turned on. 
FIG. 5 shows a drive transmitting member used in the drive supply means 56 
shown in FIG. 2 in which the drive transmitting member is controlled by 
the drive control means 53 such that the rotational speed of the fixing 
rollers 31 and 34 is set for the synthetic resin films at a value smaller 
than that for the sheet of paper. It is of course that this drive 
transmitting member may be combined with the respective mechanisms shown 
in FIG. 2 for various purposes. 
The image forming system includes a drive mechanism shown by D in FIG. 5 
and which is disposed in place. 
This drive mechanism D comprises a drive motor 100 and a gear 101 mounted 
on the output shaft of the motor. The gear 101 is meshed with a gear 102a 
integrally mounted on a shaft 103 disposed parallel to the motor shaft, of 
a gear member 102, which also includes a gear 102b mounted integrally 
thereon. The shaft 103 supports a gear 104 through a clutch 105, the gear 
104 having a diameter larger than that of the gear 102b. The gear 102b 
engages an enlarged-diameter gear 106 mounted on a shaft 103' which is 
arranged parallel to the shaft 103. The shaft 103' also supports a gear 
107 through a clutch 108. A sprocket wheel S.sub.1 is fixedly mounted on 
the shaft 103' outside the gear 107 (opposite side to the gear 106). 
In such an arrangement, when the clutch 105 is disengaged and the clutch 
108 is engaged, the drive of the motor 100 is transmitted to the sprocket 
wheel S.sub.1 through the gears 101, 102a via the gears 102b, 106 and 103' 
as shown by solid line in FIG. 5. When the clutch 105 is engaged and the 
clutch 108 is disengaged, the driving force is transmitted from the motor 
to the sprocket wheel S.sub.1 through the gears 101, 102a, 102b, 104 and 
107 via the shaft 103' as shown by broken line in FIG. 5. 
By appropriately selecting gear ratios with respect to the intermediate 
gears 102a, 106, 104 and 107, therefore, the sprocket wheel S.sub.1 can 
selectively be rotated at one of two rotational speeds. 
A chain E is spanned between the sprocket wheel S.sub.1 and the other 
sprocket wheels S.sub.2 and S.sub.3 such that gears 109 and 110 mounted on 
the shaft of the sprocket wheel S.sub.3 will be drived at the selected one 
of two rotational speeds. 
The drive mechanism D is disposed within the image forming system to 
include the gear train from the drive motor to the gear 110. 
As described hereinbefore, the system shown in FIG. 1 has a path along 
which the recording material are to be conveyed and in which the fixing 
apparatus A is arranged which include the fixing rollers 38, 31 and 34. 
The roller 38 has a shaft fixedly supporting a gear 116 at the outside end 
while the shaft of the roller 34 supports a gear 113 fixedly mounted 
thereon at the outer end. 
The final output gear 110 in the drive mechanism is connected with a gear 
111 in the fixing apparatus A through an appropriate coupling 112. The 
gear 111 engages the gear 113 to drive the roller 34. The gear 111 also 
engages the gear 116 through intermediate gears 114a through 114d to drive 
the roller 31. In the illustrated embodiment, the roller 38 is 
frictionally driven by the rollers 31 and 34. 
The selection of the fixing rollers into a second speed or a first speed 
smaller than the second speed is carried out as follows. When a 
transparent resin sheet is to be used, a transparent material mode switch 
on the operation panel is turned on to engage the clutch 108 to change the 
fixing rollers from the second speed to the first speed. When a sheet of 
ordinary paper is to be used, the above switch is turned off to engage the 
clutch 105 to return the fixing rollers to the second speed. 
Alternatively, when the transparent resin sheet is to be used, this may be 
detected during the copy cycle to generate a signal which is in turn 
supplied to the clutch. For example, if light emitting and receiving 
elements are disposed near the paper guide, conveyor belt or any other 
suitable location in the path such that the amount of light travelling 
between the light emitting and receiving elements during the passage of a 
recording material therebetween is previously determined by the use of 
clock pulses, the recording material may be moved at its appropriate speed 
by engaging the clutch 8 when the above amount of light indicates a 
transparent material or by engaging the clutch 105 when the amount of 
light indicates a sheet of ordinary paper. 
When a color image is carried on a transparent sheet and projected onto a 
screen, the projected light is complicatedly deflected since the surface 
of the toner image is reduced in flatness if any non-fused toner particles 
exist on the toner image. If air cavities are formed between the non-fused 
toner particles having irregular surfaces in the toner layer, the 
projected light will have less parallel moving light beams to adversely 
affect the projected image through the entire thickness of the toner 
layer. In such a case, the conditions of fixation is required to be more 
severe than those required when the image is observed under any reflective 
light. This problem has been solved in accordance with the present 
invention. 
While the invention has been described with reference to the structure 
disclosed herein, it is not confined to the details set forth and this 
application is intended to cover such modifications or changes as may come 
within the purposes of the improvements or the scope of the following 
claims.