Image forming apparatus having a fixing device and a conveyer means for conveying a recording member to the fixing device

An image forming apparatus for forming an image on a recording member includes an unfixed image forming device for forming an unfixed image on the recording member, a fixing section which has a nip, and which holds and conveys the recording member carrying the unfixed image through the nip to fix the unfixed image on the recording member, and a conveyor for conveying the recording member to the fixing section. The conveyor can convey the recording member at a first speed, or at a second speed which is slower than the first speed. The conveyor conveys the recording member at the first speed before a leading end of the recording member is held by the nip, and at the second speed after the leading end is held by the nip. With such a construction, the recording member can be forcibly inserted into the nip, and can be prevented from slipping at the entrance of the nip.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an image forming apparatus having a fixing 
device for fixing an unfixed image carried by a recording member, and a 
means for conveying the recording member carrying the unfixed image to the 
fixing device. 
2. Description of the Related Art 
A conventional image forming apparatus will be described. 
In a fixing device of a conventional image forming apparatus, it is common 
for a fixing roller and a pressure roller to be pressed into contact with 
each other to form a nip therebetween, and for a recording member carrying 
an unfixed toner image to be clamped and conveyed by the nip to perform 
fixing. 
In an apparatus of this type, when an image forming operation is performed 
on a recording member having at least a resin layer on the surface 
thereof, such as a transparent laminated film for OHP and a coated paper, 
it is preferable to smooth the surface of the fixed image for obtaining an 
excellent image quality. To this end, fixing is performed by improving 
fixing properties, and by applying a larger amount of heat to the toner so 
as to sufficiently fuse the toner. 
In addition, when the recording member is cardboard, a large amount of heat 
is absorbed by the cardboard. Thus, the fixing is performed by improving 
fixing properties and by applying a larger amount of heat to the recording 
member. 
In order to improve fixing properties, fixing temperatures may be 
increased. However, it takes a long period of time to increase the 
temperatures. Thus, from the viewpoint of responsiveness, it is not 
preferable to improve fixing properties by increasing fixing temperatures. 
It is preferable from the viewpoint of responsiveness to improve fixing 
properties by reducing a speed of a fixing device conveying the recording 
member for prolonging the fixing time. 
Conventionally, when the recording member is the transparent laminated 
film, a speed of a conveyor belt for conveying the transparent laminated 
film to the fixing device is slowed down before the transparent laminated 
film reaches the fixing device. 
That is to say, the recording member moves into a nip formed between the 
roller pair at the same reduced speed as the reduced rotative speed of the 
roller pair. 
However, when the recording member is conveyed to the nip at the same speed 
as the roller pair, which is rotating at a low speed, the recording member 
becomes difficult to move into the nip, and the time required for the 
entire image forming may be prolonged. 
In addition, since a releasing oil applied to or impregnated in the surface 
of the rollers is accumulated in the vicinity of the nip formed between 
the rollers, the recording member may slip and jam at the entrance of the 
nip and stains may be produced on the recording member. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an image forming 
apparatus in which no slippage of a recording member is caused before the 
recording member is clamped by a nip of fixing means. 
It is another object to provide an image forming apparatus taking a short 
period of time for forming an image by increasing the speed of the 
recording member to be conveyed to the nip of the fixing means. 
According to one aspect of the present invention, an image forming 
apparatus comprises an unfixed image forming means for forming an unfixed 
image on a recording member; fixing means having a nip, the fixing means 
holding and conveying the recording member carrying the unfixed image with 
the nip and fixing the unfixed image onto the recording member; and 
conveyor means for conveying the recording member to the fixing means, 
wherein the conveyor means can convey the recording member at one of a 
first speed and a second speed slower than the first speed, and wherein 
the conveyor means conveys the recording member at the first speed before 
the leading end of the recording member enters the nip, and at the second 
speed after the leading end enters the nip. 
According to another aspect the present invention, an image forming 
apparatus comprises an unfixed image forming means for forming an unfixed 
image on a recording member conveyed with a first speed; fixing means for 
fixing the unfixed image on the recording member; and conveyor means for 
conveying the recording member to the fixing means, wherein the conveyor 
means selectively conveys the recording member at one of the first speed 
and a second speed which is faster than the first speed. 
According to yet another aspect of the present invention, a fixing device 
comprises a rotation member having a release agent on the surface thereof; 
and a press-contact member pressed into contact with the rotation member 
and forming a nip therebetween, wherein the rotation member can rotate at 
one of a first speed and a second speed slower than the first speed, and 
wherein the rotation member rotates at the first speed before a leading 
end of the recording member is held by the nip, and at the second speed 
after the leading end of the recording member is held by the nip. 
Further objects, features, and advantages of the present invention will 
become apparent from the following description of the preferred 
embodiments with reference to the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A first embodiment of the present invention will now be described with 
reference to the accompanying drawings. 
FIG. 6 is a schematic sectional view of a full-color copier which is an 
image forming apparatus to which the present invention is applied; FIG. 7 
is an enlarged view of an image forming section of FIG. 6; and FIG. 8 is 
an enlarged view of a fixing device of FIG. 6. 
The full-color copier will be briefly described with reference to FIGS. 6 
to 8. 
As shown in FIG. 6, four image forming stations for forming an image and 
each having a developing device and the like are provided around an 
electrophotographic photosensitive member (hereinafter, referred to as "a 
photoconductive drum") which is a latent image carrier, so that images on 
the photoconductive drum formed by the image forming stations Pa, Pb, Pc 
and Pd are transferred to a recording member P (also, referred to as a 
transfer paper P) such as a plain paper sheet on a conveyer means which 
moves adjacent to the photoconductive drum. 
Above the image forming stations, a reader section is provided for reading 
originals by a photoelectric conversion element such as a CCD. 
As shown in FIG. 7, in the image forming stations Pa, Pb, Pc and Pd for 
forming the magenta, cyan, yellow and black images, respectively, 
photoconductive drums 1a, 1b, 1c and 1d are disposed. Each of the 
photoconductive drums 1(a)-1(d) are rotatable in the directions of the 
arrows. Charging units 12a, 12b, 12c and 12d, laser scanning sections, 
developing units 2a, 2b, 2c and 2d, and cleaners 4a, 4b, 4c and 4d are 
sequentially provided along the direction of the rotation of the 
photoconductive drums 1a, 1b, 1c and 1d. A transfer section 3 is provided 
under the photoconductive drums 1(a)-1(d). The transfer section 3 includes 
a transfer belt 31 which is a recording member conveyer means common to 
each of the image forming stations P(a)-P(d) and transfer charging units 
3a, 3b, 3c and 3d. 
In such a copier as described above, transfer paper P fed from a paper 
feeding cassette 61, which is the recording member feeding means shown in 
FIG. 6, is supported on the transfer belt 31 and conveyed to the image 
forming sections P(a)-P(d), so that toner images of each color formed on 
the photoconductive drums 1a, 1b, 1c and 1d are sequentially transferred 
thereon. When the transfer step is finished, the transfer paper P is 
separated from the transfer belt 31, and is conveyed to a fixing device 5 
by a conveyor belt 62 which is a recording member guide means. 
The fixing device 5, as shown in detail in FIG. 8, includes a fixing roller 
51 which is a rotatably provided fixing rotation member, a pressure roller 
52 which is a pressing rotation member rotating while press-contacting the 
fixing roller 51, a release agent application device 53 for supplying and 
applying a release agent, and roller cleaning devices 54 and 55. Heaters 
56 and 57, such as halogen lamps, are provided inside of the fixing roller 
51 and pressure roller 52, respectively. Thermistors 58 and 59 are 
provided so as to come into contact with the fixing roller 51 and the 
pressure roller 52, respectively. By controlling voltages to be applied to 
the heaters 56 and 57 through a temperature control circuit, temperatures 
on the surfaces of the fixing roller 51 and the pressure roller 52 are 
controlled. 
In addition, the cleaning device 54 and the release agent application 
device 53 contact the fixing roller 51. A toner offset on the fixing 
roller 51 is cleaned by the cleaning device 54, and a release agent such 
as silicon oil is applied to the fixing roller 51 by release agent 
application device 53 so that the transfer paper P is easily separated 
from the fixing roller 51 and the toner is prevented from offsetting. 
The cleaning device 54 consists of a cleaning web 54a formed of a 
belt-shaped heat-resistant unwoven cloth, a pressing roller 54b for 
pressing the cleaning web 54a to the fixing roller 51, a supply roller 54c 
for supplying a new length of cleaning web 54a, and a take-up roller 54d 
for gradually taking up the cleaning web 54a having cleaning capability 
lowered by toner and the like adhered thereon. Particularly, the cleaning 
device 54 is provided upstream of the direction of rotation of the fixing 
roller 51 with respect to the thermistor 58 in order that the offset toner 
will not adhere to the thermistor 58 to cause poor detection by the 
thermistor 58. 
The release agent application device 53 includes an oil tank 53a containing 
a release agent such as silicon oil, rollers 53b and 53c for supplying the 
release agent from the oil tank 53a, an application roller 53d for 
applying the release agent or oil supplied from the rollers 53b and 53c, 
and a blade 53e for controlling the amount of application of the oil from 
the application roller 53d. More particularly, the release agent 
application device 53 is provided downstream of the direction of rotation 
of the fixing roller 51 with respect to the thermistor 58 in order to 
apply the oil uniformly to the fixing roller 51. The application roller 
53d has a sponge rubber which the surface is coated with a silicon rubber, 
and abuts against the fixing roller 51 to apply the oil to the fixing 
roller 51. 
The cleaning device 55 includes a cleaning web 55a, a pressing roller 55b, 
a supply roller 55c and take-up roller 55d similar to those of the 
cleaning device 54 of the fixing roller 51 and also contact the pressure 
roller 52 to perform cleaning of the toner adhered to the pressure roller 
52 by the fixing roller 51. 
In addition, an oil removing blade 60, which is a release agent removing 
elastic member for removing excess release agent remaining on the pressure 
roller 52, abuts against the pressure roller 52. When the oil removing 
blade 60 is not provided, the excess release agent accumulates in a nip 
formed between the fixing roller 51 and the pressure roller 52 
(hereinafter, referred to as a fixing nip) to produce a stain on the 
recording member P, or a recording member P at least having a resin layer 
on the surface thereof such as a transparent laminated film for use in an 
OHP slips to impede entry of the recording member P to the fixing nip. As 
a material of the oil removing blade 60, silicon rubber or fluorine rubber 
may be used. The blade 60 abuts against the pressure roller 52 with a 
suitable amount of pressure to remove excess release agent and contacts 
the pressure roller 52 in the forward or reverse direction with respect to 
the direction of rotation of the pressure roller 52. 
In this state, when the transfer paper P is conveyed into the fixing device 
5, the fixing roller 51 and pressure roller 52 rotate and silicon oil is 
applied as the release agent to the surface of the fixing roller 51. The 
transfer paper P is pressurized and heated with a substantially constant 
pressure and temperature on both sides when passing through the fixing nip 
formed by, the fixing roller 51 and the pressure roller 52 collectively 
referred to as a fixing roller pair 51 and 52. An unfixed toner image on 
the surface of the transfer paper P is melted to be fixed so that a 
full-color image is formed on the transfer paper P. The transfer paper P 
on which the image is fixed is separated from the pressure roller 52 by 
means of a lower separator lug 68 and discharged out of the fixing device 
5. 
Since the length the conveyor belt 62 can convey the transfer paper P in 
this embodiment is longer than a maximum length in a direction of 
conveyance of the standard transfer paper P which the apparatus is set to 
form image onto, a trailing end of the transfer paper P will not be loaded 
on the transfer belt 31 when a leading end is clamped by the fixing nip 
formed by the fixing roller pair 51 and 52. In other words, transferring 
and fixing are not performed simultaneously on the same transfer paper P. 
The transfer belt 31, conveyor belt 62 and fixing roller pair 51 and 52 are 
separately driven, and rotative speeds of the conveyor belt 62 and fixing 
roller pair 51 and 52 can be varied. 
In the event that the recording member P is a plain paper (thickness: about 
90 .mu.m) (a first mode), the recording member is conveyed by the transfer 
belt 31, conveyer belt 62 and the fixing roller pair 51 and 52 at a 
constant speed (140 mm/sec). 
A fixing operation when a transparent laminated film for OHP having at 
least a resin layer on the surface thereof is used as the recording member 
P will now be described with reference to FIG. 1. 
Referring to FIG. 1, the horizontal axis represents the time after starting 
a copying operation, and the vertical axis represents the rotative speeds 
of the fixing roller pair 51 and 52 and the conveyor belt 62. When a 
transparent laminated film mode (second mode) is set, and a copy button is 
pressed to start a copying operation, the fixing roller pair 51 and 52, 
and the conveyor belt 62 start to rotate at a speed of 140 mm/sec for 
conveying the transparent laminated film in accordance with the speed of 
the image forming section, e.g. transfer belt 31. Since the speed of the 
image forming section does not vary in accordance with the type of the 
recording member, the transfer belt 31 conveys the transparent laminated 
film at the same speed for conveying the plain paper. 
After the trailing end of the transparent laminated film has passed through 
a final transfer position and a predetermined time of 60 msec expires 
since the leading end has moved into the entrance of the fixing nip, the 
speeds of the fixing roller pair 51 and 52 and the conveyor belt 62 are 
reduced from 140 mm/sec to 70 mm/sec, and increased to 140 mm/sec again 
after completion of fixing. That is, the conveyor belt 62 synchronizes its 
speed with the speed of fixing roller pair 51 and 52 to convey the 
transparent laminated film at the same speed. FIG. 2 illustrates the state 
of the fixing nip when the rotative speed of the fixing roller pair 51 and 
52 is switched from 140 mm/sec to 70 mm/sec. As shown in FIG. 2, according 
to this embodiment, when the leading end of the transparent laminated film 
gets to the position (2), where 60 msec has passed since it reached the 
entrance (1) of the fixing nip, in other words, when the leading end of 
the transparent laminated film is clamped by the fixing roller pair 51 and 
52 and the leading end exits the fixing nip at position (3), the rotative 
speed of the fixing roller pair 51 and 52 is switched from 140 mm/sec to 
70 mm/sec. In this embodiment, since the width of the fixing nip N is 7.5 
mm and the transparent laminated film advances 8.4 mm (=140 
mm/sec.times.60 msec) from the entrance of the fixing nip, the rotative 
speed of the fixing roller pair 51 and 52 is switched when the leading end 
exits the fixing nip by 0.9 mm (=8.4 mm-7.5 mm). 
In addition, according to this embodiment, the leading end of the 
transparent laminated film includes 13 mm of a leading end margin W on 
which no image is formed. When the leading end of the transparent 
laminated film is at the position of (2), the trailing end of the leading 
end margin W, e.g., the leading end of the image area, does not move into 
the fixing nip. That is, the distance the leading end of the transparent 
laminated film advances from the entrance of the fixing nip before the 
rotative speed of the fixing roller pair 51 and 52 is changed may be 
preferably shorter than the length of the leading end margin W of the 
transparent laminated film. 
The reason for reducing the rotative speed of the fixing roller pair 51 and 
52 with the above timing will now be described. 
When an image is fixed on the transparent laminated film, the rotative 
speed of the fixing roller pair 51 and 52 is reduced to 70 mm/sec and the 
fixing time is prolonged to improve fixing properties. Thus, the surface 
of the image formed on the transparent laminated film can be smoothed to 
obtain a good image quality. 
However, since the fixing roller pair 51 and 52 rotates slowly, oil or any 
other release agent applied to, and impregnated on the surfaces of the 
fixing roller pair 51 and 52 may usually accumulate at the entrance of the 
fixing nip. 
According to this embodiment, at the moment when the transparent laminated 
film moves into the fixing nip, the rotative speed of the fixing roller 
pair 51 and 52 is not reduced but is maintained at a normal speed (140 
mm/sec), the image forming speed (e.g., the speed of transfer belt 31). 
Therefore, the accumulation of oil at the entrance of the fixing nip can 
be prevented, whereby the transparent laminated film can be securely 
clamped. 
In addition, according to this embodiment, the speed of the conveyor belt 
62 for conveying the transparent laminated film to the fixing roller pair 
51 and 52 remains at a high speed (140 mm/sec) when the transparent 
laminated film moves into the entrance of the fixing nip. Therefore, the 
transparent laminated film can be forcibly conveyed to the fixing nip, 
whereby slippage of the transparent laminated film caused at the time of 
rushing into the fixing nip can be prevented more surely. 
Further, according to this embodiment, the leading end of the transparent 
laminated film is clamped and the fixing speed becomes slow before the 
image area moves into the fixing nip. Therefore, jamming or deterioration 
of image fixing properties is prevented. 
In this embodiment, the speeds of the fixing roller pair 51 and 52 and the 
conveyor belt 62 are reduced after 60 msec since the leading end of the 
transparent laminated film has rushed into the fixing nip. However, the 
time of 60 msec is not limited thereto because it varies in accordance 
with the speed of the conveyor belt 62 of the apparatus. The speeds of the 
fixing roller pair 51 and 52 and the conveyor belt 62 may be reduced at 
least after an inrush of the transparent laminated film into the fixing 
nip. 
A first comparative embodiment of this embodiment will now be described 
with reference to FIG. 3. 
In FIG. 3, the speeds of the fixing roller pair 51 and 52 and the conveyor 
belt 62 are reduced from 140 mm/sec to 70 mm/sec after the trailing end of 
the transparent laminated film passes through the final transfer position 
and before the leading end rushes into the fixing nip. In this case, when 
the transparent laminated film rushes into the fixing nip, the speeds of 
the fixing roller pair 51 and 52 and the conveyor belt 62 are 70 mm/sec. 
Thus, oil accumulates at the entrance of the fixing nip and the force of 
the transparent laminated film when rushing into the fixing nip becomes 
small as compared with the timing shown in FIG. 1, thereby causing 
slippage of the transparent laminated film at the time of rushing into the 
fixing nip. Therefore, as described in the first embodiment, by reducing 
the speeds of the fixing roller pair 51 and 52 and the conveyor belt 62 
with the timing at least after inrush of the leading end of the 
transparent laminated film into the fixing nip, the slippage of the 
transparent laminated film is eliminated, and a good fixing of the image 
to the transparent laminated film can be performed. 
A variable speed sequence of this embodiment is not limited to the 
transparent laminated film. It may be preferably applied also to a 
recording member P having a smooth surface, such as a coated paper having 
at least a resin layer on the surface thereof. More particularly, the 
transparent laminated film and coated paper are slippery because the 
surfaces thereof are resins, and the variable speed sequence of this 
embodiment may be effectively performed. 
A second embodiment of the present invention will now be described. Since 
the basic construction of the apparatus is similar to that of the first 
embodiment, only the differences between the embodiments will be 
described. 
In this embodiment, a variable speed sequence in which the recording member 
P is cardboard having a thickness (for example, 200 .mu.m) thicker than 
the plain paper thickness will be described with reference to FIGS. 4 and 
5. 
Referring to FIG. 4, the horizontal axis represents the time after the 
start of a copying operation, and the vertical axis represents the 
rotative speeds of the fixing roller pair 51 and 52 and the conveyor belt 
62. When a cardboard mode (an alternative second mode) is set, and a copy 
button is pressed to start a copying operation, the fixing roller pair 51 
and 52, and the conveyor belt 62 start to rotate at a speed of 140 mm/sec 
for conveying the cardboard in accordance with the speed of the image 
forming section, e.g. transfer belt 31. 
After the trailing end of the cardboard has passed through a final transfer 
position and a predetermined time of 26 msec expires since the leading end 
has moved into the entrance of the fixing nip, the speeds of the fixing 
roller pair 51 and 52 and the conveyor belt 62 are reduced from 140 mm/sec 
to 70 mm/sec, and increased to 140 mm/sec again after completion of fixing 
to discharge the cardboard. 
FIG. 5 illustrates the state of the fixing nip when the rotative speed of 
the fixing roller pair 51 and 52 is switched from 140 mm/sec to 70 mm/sec. 
As shown in FIG. 5, according to this embodiment, when the leading end of 
the cardboard gets to the position (2), where 26 msec has passed since the 
leading end reached the entrance (1) of the fixing nip, in other words, 
when the leading end of the cardboard is clamped by the fixing roller pair 
51 and 52 and the leading end reaches the fixing nip, the rotative speed 
of the fixing roller pair 51 and 52 is switched from 140 mm/sec to 70 
mm/sec. In this embodiment, since the width of the fixing nip N is 7.5 mm 
and the cardboard advances about 3.6 mm (=140 mm/sec.times.26 msec) from 
the entrance of the fixing nip, the rotative speed of the fixing roller 
pair 51 and 52 is switched when the leading end gets to a substantially 
center portion of the fixing nip. 
In addition, according to this embodiment, the leading end of the cardboard 
includes 4 mm of a leading end margin W on which no image is formed. When 
the leading end of the cardboard is at the position of (2), the trailing 
end of the leading end margin W, e.g. the leading end of the image area, 
does not move into the fixing nip. 
According to this embodiment, in the event that an image is fixed on the 
cardboard, the rotative speed of the fixing roller pair 51 and 52, which 
is the fixing speed, is reduced to 70 mm/sec to increase fixing 
properties. Thus, heat and pressure can be sufficiently applied throughout 
the recording member even if the recording member is cardboard, so that 
good image quality can be obtained. 
Usually, due to the reduced speed of the fixing roller pair 51 and 52, the 
oil accumulated at the entrance of the fixing nip and the leading end of 
the cardboard slips on the fixing roller pair 51 and 52 before moving into 
the fixing nip, so that it sometimes becomes incapable of moving into the 
fixing nip. Even when the leading end of the cardboard can move into the 
fixing nip, the oil accumulated at the entrance of the fixing nip may 
produce stains on the cardboard. 
According to this embodiment, at the moment when the cardboard moves into 
the fixing nip, the rotative speed of the fixing roller pair 51 and 52 is 
not reduced but is maintained at a normal speed (140 mm/sec), the image 
forming speed (e.g., the speed of transfer belt 31). Therefore, the 
accumulation of oil at the entrance of the fixing nip can be prevented, 
whereby the cardboard can be securely clamped. 
In addition, production of stains due to the oil accumulated at the 
entrance of the fixing nip can be prevented. 
Further, according to this embodiment, the speed of the conveyor belt 62 
for conveying the cardboard to the fixing roller pair 51 and 52 remains at 
a high speed (140 mm/sec) when the cardboard moves into the entrance of 
the fixing nip. Therefore, the cardboard can be forcibly conveyed to the 
fixing nip, whereby slippage of the cardboard caused at the time of 
rushing into the fixing nip can be prevented more surely. 
Still further, according to this embodiment, since the leading end of the 
cardboard is clamped and the fixing speed becomes slow before the image 
area moves into the fixing nip, fixing properties of the image will not be 
deteriorated. 
In this embodiment, the speeds of the fixing roller pair 51 and 52 and the 
conveyor belt 62 are reduced after 26 msec since the leading end of the 
cardboard rushed into the fixing nip. However, the time of 26 msec is not 
limited thereto because it varies in accordance with the speed of the 
conveyor belt 62 of the apparatus. The speeds of the fixing roller pair 
and the conveyor belt 62 may be reduced at least after an inrush of the 
cardboard into the fixing nip. 
A third embodiment of the present invention will now be described with 
reference to FIGS. 9(A) to 11(C). Since the basic construction of the 
apparatus is similar to that of the first embodiment, only the differences 
between the embodiments will be described. 
A fixing operation in which a transparent laminated film for OHP having at 
least a resin layer on the surface thereof is used as the recording member 
P will be described with reference to FIGS. 9(A)-(C). Referring to FIGS. 
9(A)-(C), the horizontal axes represent the time after the start of a 
copying operation, and the vertical axes represent the rotative speed of 
the transfer belt 31 corresponding to the speed of the image forming 
section of the body of the apparatus, the rotative speed of the conveyor 
belt 62 and the rotative speed of the fixing roller pair 51 and 52, 
respectively. 
When a transparent laminated film mode is set, and a copy button is pressed 
to start the copying operation, the conveyor belt 62 starts to rotate at a 
speed of 140 mm/sec, similar to that for conveying the plain paper 
(thickness: about 90 .mu.m), in accordance with the speed (140 mm/sec) of 
the image forming section of the apparatus, e.g., the speed of transfer 
belt 31 and the fixing roller pair 51 and 52 start to rotate at a speed 
for fixing the transparent laminated film for OHP (70 mm/sec), which is 
lower than the speed for fixing the plain paper, to prevent abrasions of 
the rollers. 
After the trailing end of the transparent laminated film has passed through 
a final transfer position and a predetermined time of 125 msec expires 
since the leading end has moved into the entrance of the fixing nip, the 
speed of the conveyor belt 62 is reduced from 140 mm/sec to 70 mm/sec, and 
increased to 140 mm/sec again after completion of fixing. 
FIG. 10 illustrates the state of the fixing nip when the rotative speed of 
the conveyor belt 62 is switched from 140 mm/sec to 70 mm/sec. 
As shown in FIG. 10, according to this embodiment, when the leading end of 
the transparent laminated film gets to the position (2) where 125 msec has 
passed since it reached the entrance (1) of the fixing nip, in other 
words, when the leading end of the transparent laminated film is clamped 
by the fixing roller pair 51 and 52 and the leading end exits the fixing 
nip at position (3), the speed of the conveyor belt 62 is switched from 
140 mm/sec to 70 mm/sec. In this embodiment, the width of the fixing nip N 
is 7.5 mm and the speed of the conveyor belt 62 is switched at the 
position (2) where the transparent laminated film advances 8.75 mm (=70 
mm/sec.times.125 msec) from the entrance of the fixing nip. In addition, 
according to this embodiment, the leading end of the transparent laminated 
film includes 13 mm of a leading end margin W on which no image is formed. 
When the leading end of the transparent laminated film is at position (2), 
the trailing end of the leading end margin W, e.g., the leading end of the 
image area, does not move into the fixing nip. 
According to this embodiment, the fixing roller pair 51 and 52 rotates at a 
low speed for fixing the unfixed toner image formed in the image forming 
section. Thus, abrasions of the roller pair 51 and 52 can be prevented, 
thereby improving their durability. 
In addition, the speed of the conveyor belt 62 for conveying the 
transparent laminated film to the fixing roller pair 51 and 52 remains at 
a high speed (140 mm/sec) when the transparent laminated film moves into 
the entrance of the fixing nip. Therefore, the transparent laminated film 
can be forcibly conveyed to the fixing nip, whereby slippage of the 
transparent laminated film caused at the time of rushing into the fixing 
nip can be prevented. 
Further, since the speed of the conveyor belt 62 at the time of fixing is 
the same as the rotative speed of the fixing roller pair 51 and 52 (70 
mm/sec), jamming and image deterioration are prevented. 
The speed of the conveyor belt 62 when rushing into the fixing nip may be 
faster than the rotative speed of the fixing roller pair 51 and 52, and 
need not be the same as the speed for conveying the plain paper. 
The difference in speed between the conveyor belt 62 and the fixing roller 
pair 51 and 52 at the time of the inrush of the transparent laminated film 
into the fixing nip may preferably be relatively large because an inrush 
force of the transparent laminated film should be large. 
Still further, according to this embodiment, the speed of the conveyor belt 
62 is reduced after the leading end of the transparent laminated film is 
clamped in the fixing nip and before the image area moves into the fixing 
nip. Therefore, there is no bad influence on the image to deteriorate the 
image quality. 
In this embodiment, the speed of the conveyor belt 62 is reduced after 125 
msec since the leading end of the transparent laminated film rushes into 
the fixing nip. However, the time of 125 msec is not limited thereto 
because it varies in accordance with the speed of the conveyor belt 62 of 
the apparatus. The speeds of the fixing roller pair 51 and 52 and the 
conveyor belt 62 may be reduced at least after an inrush of the leading 
end of the transparent laminated film into the fixing nip. 
A second comparative embodiment of this embodiment will be described with 
reference to FIGS. 11(A)-(C). 
In FIGS. 11(A)-(C), the speeds of the fixing roller pair 51 and 52 and the 
conveyor belt 62 are reduced from 140 mm/sec to 70 mm/sec after the 
trailing end of the transparent laminated film passes through the final 
transfer position and before the leading end rushes into the fixing nip. 
In this case, when the transparent laminated film rushes into the fixing 
nip, the speeds of the fixing roller pair 51 and 52 and the conveyor belt 
62 are 70 mm/sec. Thus, the force of the transparent laminated film when 
rushing into the fixing nip becomes smaller than the force when rushing 
into the fixing nip at the timing shown in FIGS. 9(A)-9(C), whereby 
slippage of the transparent laminated film may result when rushing into 
the fixing nip. 
As described above, according to the third embodiment, by reducing the 
speed of the conveyor belt 62 to match the rotative speed of the fixing 
roller pair 51 and 52 after the leading end of the transparent laminated 
film has rushed into the fixing nip, the slippage of the transparent 
laminated film caused when rushing into the fixing nip can be prevented 
while improving durability of the fixing roller pair 51 and 52. 
A fourth embodiment of the present invention will now be described. Since 
the basic construction of the apparatus is similar to that of the first 
embodiment, only the differences between the embodiments will be 
described. 
This embodiment relates to an apparatus in which the rotative speed of the 
fixing roller pair 51 and 52 for fixing an unfixed image on the recording 
member P is faster than the image forming speed of the image forming 
section, e.g., the transfer belt 31. 
When the image forming speed of the image forming section is slow, the 
image quality can be improved because when the rotative speed of the 
photoconductive drum is slowed down, the amount of light per unit of 
picture element increases, a contrast of a latent image can be easily 
obtained, developing properties are improved, and the picture element 
density can be increased. However, when the fixing speed is too slow in 
accordance with the image forming speed of the image forming section, an 
offset phenomenon in which the toner adheres to the fixing roller 51, and 
a poor separation of the recording member from the fixing roller 51 may 
result. Therefore, in this embodiment, an optimum fixing speed is faster 
than the image forming speed of the image forming section, e.g., the 
transfer belt 31. 
A variable speed sequence of the rotative speeds of the transfer belt 31, 
conveyor belt 62 and the fixing roller pair 51 and 52 of this embodiment 
will be described with reference to FIGS. 12(A)-(C). 
Referring to FIGS. 12(A)-(C), the horizontal axes represent the time after 
the start of a copying operation, and the vertical axes represent the 
rotative speeds of the transfer belt 31, the conveyor belt 62 and the 
fixing roller pair 51 and 52, respectively. In FIGS. 12(A)-(C), when the 
copy button is pressed to start copying, the conveyor belt 62 starts to 
rotate at a speed of 45 mm/sec, which is the speed in a mode of high image 
quality, in accordance with the speed of the image forming of the image 
forming section of the apparatus, e.g., the rotative speed of the transfer 
belt 31, and the fixing roller pair 51 and 52 start to rotate at a speed 
for fixing the transparent laminated film for OHP (70 mm/sec) to prevent 
abrasions of the fixing roller pair 51 and 52. 
In this state, the transparent laminated film is fed to the image forming 
section, and the image is formed at an image forming speed of 45 mm/sec. 
That is, the transfer belt 31 rotates at a speed of 45 mm/sec. At the 
point of time when the trailing end of the transparent laminated film 
passes through the final transfer position to get on the conveyor belt 62 
after completion of the image forming, the speed of the conveyor belt 62 
is increased to 140 mm/sec. 
After a predetermined time of 125 msec expires after the leading end of the 
transparent laminated film has moved into the fixing nip, the speed of the 
conveyor belt 62 is reduced from 140 mm/sec to 70 mm/sec, and increased to 
140 mm/sec again after completion of fixing. The state of the fixing nip 
when the speed of the conveyor belt 62 is switched from the 140 mm/sec to 
70 mm/sec is the same as that in the third embodiment. 
As shown in FIG. 10, according to this embodiment, when the leading end of 
the transparent laminated film gets to the position (2) where 125 msec has 
passed since it reached the entrance (1) of the fixing nip, in other 
words, when the leading end of the transparent laminated film is clamped 
by the fixing roller pair 51 and 52 and the leading end gets out of the 
fixing nip, the speed of the conveyor belt 62 is switched from 140 mm/sec 
to 70 mm/sec. In this embodiment, the width of the fixing nip N is 7.5 mm 
and the speed of the conveyor belt 62 is switched at the position 
(position (2)) where the transparent laminated film advances 8.75 mm (=70 
mm/sec.times.125 msec) from the entrance of the fixing nip. 
In addition, according to this embodiment, the leading end of the 
transparent laminated film includes 13 mm of a leading end margin W on 
which no image is formed. When the leading end of the transparent 
laminated film is at position (2), the trailing end of the leading end 
margin W, e.g., the leading end of the image area does not move into the 
fixing nip. 
According to this embodiment, the image forming speed is slow (45 mm/sec), 
whereby an image of high quality can be formed. 
In addition, since the speed of the conveyor belt 62 is increased after the 
trailing end of the transparent laminated film passes through the final 
transfer position, there is no deterioration of the image due to a 
transfer offset. 
Further, the speed of the conveyor belt 62 for conveying the transparent 
laminated film to the fixing roller pair 51 and 52 remains at a high speed 
(140 mm/sec) when the recording member moves into the entrance of the 
fixing nip. Therefore, the transparent laminated film can be forcibly 
conveyed to the fixing nip, whereby slippage of the transparent laminated 
film caused when rushing into the fixing nip can be prevented. 
Still further, since the speed of the conveyor belt 62 at the time of 
fixing is the same as the rotative speed of the fixing roller pair 51 and 
52 (70 mm/sec), there is neither degradation of the image nor bad 
conveyance of the transparent laminated film. 
In this embodiment, a greater difference in speed between the conveyor belt 
62 and the fixing roller pair 51 and 52 when the transparent laminated 
film rushes into the fixing nip may also be preferable, as in the case of 
the third embodiment. 
In this embodiment, the speed of the conveyor belt 62 is reduced after 125 
msec since the leading end of the transparent laminated film rushes into 
the fixing nip. However, the time of 125 msec is not limited thereto 
because it varies in accordance with the speed of the conveyor belt 62 of 
the apparatus. The speed of the conveyor belt 62 may be reduced at least 
after an inrush of the leading end of the transparent laminated film into 
the fixing nip. 
A third comparative embodiment of this embodiment will now be described 
with reference to FIGS. 13(A)-(C). 
In FIGS. 13(A)-(C), when the rotative speeds of the transfer belt 31, and 
the conveyor belt 62 after the copying operation begins are 45 mm/sec, and 
the rotative speeds of the fixing roller pair 51 and 52 is 70 mm/sec, the 
transparent laminated film is conveyed at the speed of the 45 mm/sec at 
the time of the passage of the trailing end thereof through the final 
transfer position, and the inrush of the leading end thereof into the 
fixing nip. 
In this case, when the transparent laminated film rushes into the fixing 
nip, the speeds of the fixing roller pair 51 and 52 and the conveyor belt 
62 are 45 mm/sec. Thus, the force of the transparent laminated film when 
rushing into the fixing nip is small, whereby slippage of the transparent 
laminated film may be caused when rushing into the fixing nip. 
As described above, by increasing the speed of the conveyor belt 62 to be 
faster than that of the fixing roller pair 51 and 52, the slippage of the 
leading end of the transparent laminated film can be eliminated, and 
fixing can be performed by decreasing the speed of the conveyor belt 62 
after the leading end of the transparent laminated film rushes into the 
fixing nip. 
According to this embodiment, the speed of the conveyor belt 62 is 
increased to be faster than an image forming speed of the image forming 
section after the trailing end of the recording member P passes through 
the final transfer position. Therefore, the time required for the unfixed 
image formed on the recording member P to be fixed can be shortened, while 
preventing the image shearing on the recording member P. 
By increasing the speed of the conveyor belt 62 as described above, it is 
also possible to reduce the entire delay of the image forming time, which 
is caused by the prolonged fixing time. 
Although the fixing roller pair 51 and 52 is used as the fixing means in 
the above first to fourth embodiments, the fixing means are not limited 
thereto, and any means will be employed so long as they can form the 
fixing nip. 
In addition, in the above first to fourth embodiments, although the length 
of the conveyor belt 62 is longer than a maximum length of the transfer 
paper P, the distance between the final transfer position and the fixing 
nip may be longer than a maximum length of the transfer paper P even if 
the length of the conveyor belt 62 is shorter than the maximum length of 
the transfer paper P. 
Further, in the above first to fourth embodiments, the rotative speed of 
the fixing roller pair 51 and 52 at the time of inrush of the transparent 
laminated film or cardboard into the fixing nip may be slightly faster 
than that of the conveyor belt 62 because a pulling effect of the fixing 
nip is exhibited, so that the slippage of the transparent laminated film 
or cardboard caused when rushing into the fixing nip can be prevented more 
surely. 
More specifically, in the case of the first and the third embodiments, the 
rotative speed of the fixing roller pair 51 and 52 may be preferably set 
to about 71 to 73 mm/sec with respect to the rotative speed of 70 mm/sec 
of the conveyor belt 62, as shown in broken lines of FIGS. 1 and 9(C). 
Speed reduction sequences in the above first to fourth embodiments are not 
limited to be applied to a recording member P having a resin layer on the 
surface thereof, such as a transparent laminated film and coated paper, 
and a thick recording member P. Even if the recording member P is plain 
paper, when the speed of the fixing roller pair 51 and 52 is reduced to 
improve fixing properties and give a polish to the image, the speed 
reduction sequences similar to those of the above first and second 
embodiments may be preferably performed to prevent slippage. 
Still further, according to the above first to fourth embodiments, the 
transparent laminated film mode (or the cardboard mode) is set and the 
copy button is pressed to start the copying operation. However, the 
copying operation may be automatically started by manually feeding the 
transparent laminated film (or cardboard) into the apparatus so as to be 
detected the feeding thereof. At this time, if a recording member 
detecting means is provided in the apparatus for detecting a type and a 
thickness of the recording member P, the speed reduction sequences of the 
above first to fourth embodiments which match with the recording member P 
to be fed by only feeding the recording member P will be performed without 
a user setting the type and the thickness thereof. 
Although the preferred embodiments of the present invention have been 
described above, the present invention is not limited thereto, and any 
changes and modifications can be made without departing from the spirit 
and scope of the present invention.