Recording system

A recording system capable of detecting a deviation from a normal path of travel of an endless belt recording member trained over a plurality of rollers including a displacing roller supported at one end for pivotal movement and at the other end for displacing movement in a vertical direction and effecting correction of irregularities in the movement of the endless belt recording member. A guide member located above a side portion of a corona discharger for effecting transfer-printing of a toner image on a transfer-printing sheet in the vicinity of the displacing roller is moved in displacing movement conjointly with the displacing movement of the displacing roller, to thereby keep the clearance between the surface of the recording member and the corona discharger substantially constant at all times.

FIELD OF THE INVENTION 
This invention relates to recording systems in general, and more 
particularly it is concerned with a recording system comprising a 
recording medium in the form of an endless belt trained over a plurality 
of rollers and having a toner image formed thereon which is printed on a 
transfer-printing sheet by means of a corona discharger.

DESCRIPTION OF THE PRIOR ART 
One example of the recording system of the type described of the prior art 
is shown in FIG. 1. 
FIG. 1 is a schematic view of a recording system constructed as a laser 
printer of the electrophotographic printing type, in which the reference 
numeral 1 designates a recording medium in the form of a photosensitive 
member of an endless belt type trained over a drive roller 2 and a 
follower roller 3. The drive roller 2 is driven by drive means, not shown, 
to rotate in a clockwise direction to move the photosensitive endless belt 
member 1 in the direction of an arrow A. As the photosensitive endless 
belt member 1 moves in this way, a portion thereof is charged by a charger 
4 and an electrostatic latent image of a document to be recorded is formed 
on the surface of the charged portion of the photosensitive endless belt 
member 1 by a laser beam 5. The electrostatic latent image is developed by 
a developing device 6 into a visible image or a toner image, not shown, by 
means of a toner. The toner image is printed by transfer-printing by means 
of a corona discharger 7 on a transfer-printing sheet 9 fed from a sheet 
feeding section 8 in the direction of an arrow B in synchronism with the 
formation of the toner image on the photosensitive endless belt member 1. 
The corona discharger 7 is located in a position below the follower roller 
3. After having the toner image formed thereon by transfer-printing, the 
transfer-printing sheet 9 is stripped off the photosensitive endless belt 
member 1 by virture of its firmness and the curvature of the lower run of 
the endless belt member 1 in the vicinity of the follower roller 3, to be 
fed in the direction of an arrow B'. The transfer-printing sheet 9 fed in 
t his direction is fed to a fixing device 10, from which it is transferred 
to a discharge stacker 11. 
In the recording system of the aforesaid construction, the photosensitive 
endless belt member 1 might be prevented from moving along a predetermined 
path of travel due possibly to a difference in its length between opposite 
side edge portions or a local frictional dragging applied to the belt 
during travel. The tendency of the photosensitive endless belt member 1 to 
deviate from its normal path of travel would increase with time if it is 
allowed to operate without any means of correction. When this phenomenon 
occurs, the position in which an image is formed on the photosensitive 
endless belt member 1 and the position in which a transfer-printed image 
is formed on a transfer-printing sheet would be displaced from the normal 
position. Also, the photosensitive endless belt member 1 would be 
prevented from being driven for operation normally, and a side edge 
portion thereof would be damaged. 
To obviate this problem, a proposal has been made by the applicant of the 
subject application to provide a correction device for correcting 
irregularities in the movement of the photosensitive endless belt member 
in which a displacing roller pivotally supported at one end for vertical 
movement at the other end is used as the follower roller 3 so that the 
follower roller can be moved vertically in displacing movement when any 
deviation of the photosensitive endless belt member 1 from its normal path 
of travel is detected. One example of such device will be described by 
referring to FIGS. 1-3. 
Prior to the description of the correction device, the follower roller 
section of the recording system of the prior art will be outlined. As 
shown in FIG. 1, the follower roller 3 constructed as a displacing roller 
is pivotally supported at one end thereof (an end opposite the end of the 
follower roller shown in the plane of FIG. 1) and has at the other end 
thereof a bearing 3a fitted in a difurcation 12a formed at one end of a 
control arm 12 which is in the form of a letter L and pivotally supported 
at the junction of its long and short legs by a pin 13 secured to a 
machine frame, not shown. A solenoid 14 of a self-holding type and a 
tension spring 15 are mounted on opposite sides of the other end portion 
of the control arm 12. Stoppers 16 and 17 are mounted on opposite sides of 
the other end of the control arm 12 to regulate the amount of pivotal 
movement of the cotnrol arm 12. Upon energization of the solenoid 14, the 
control arm 12 is pulled toward the solenoid 14 and moved in a clockwise 
direction about the pin 13 against the biasing force of the spring 15 
until the other end thereof abuts against the stopper 16, so that the end 
of the follower roller 3 located in the plane of the figure is moved 
downwardly to a position in which it is lower by about 0.75 mm than the 
position in which it would be disposed if the follower roller 3 were 
located horizontally. Thus the end of the follower roller 3 in the plane 
of FIG. 1 is located at a lower level than the end thereof opposite the 
end shown in FIG. 1. Upon de-energization of the solenoid 14, the control 
arm 12 is moved by the biasing force of the spring 15 about the pin 13 in 
a counterclockwise direction until it abuts against the stopper 17. Thus, 
the end of the follower roller 3 located in the plane of FIG. 1 is moved 
upwardly to a position in which it is higher by about 0.75 mm than the 
position in which it would be disposed if the follower roller 3 were 
located horizontally, and the end of the follower roller 3 located in the 
plane of FIG. 1 is disposed at a higher level than the end thereof 
opposite the end shown in FIG. 1. 
The correction device of the prior art referred to hereinabove which is 
incorporated in the recording system shown in FIG. 1 will now be 
described. Referring to FIG. 2, solenoids 14' and 14" are located 
symmetrically on opposite sides of the other end portion of the control 
arm 12 and connected thereto in a manner to hold same therebetween, and a 
spring click 15' is mounted below the other end of the control arm 12. 
When the solenoid 14' is energized, the control arm 12 is moved in a 
clockwise direction about the pin 13 and the end of the follower roller 3 
in the plane of FIG. 2 moves downwardly by about 0.75 mm from the position 
in which it would be disposed if the follower roller 3 were located 
horizontally, so that the end of the follower roller 3 located in the 
plane of FIG. 2 is kept at a level by about 0.75 mm than the opposite end 
of the follower roller 3 with respect to the horizontal. Conversely, when 
the solenoid 14" is energized, the control arm 12 is moved in a 
counterclockwise direction about the pin 13 and the end of the follower 
roller 3 in the plane of FIG. 2 moves upwardly by about 0.75 mm from the 
position in which it would be disposed if the follower roller 3 were 
located horizontally, so that the end of the follower roller 3 located in 
the plane of FIG. 2 is kept at a level higher by about 0.75 mm than the 
opposite end of the follower roller 3 with respect to the horizontal. The 
control arm 12 is held in the two positions referred to hereinabove by the 
spring click 15'. 
Control of a current passed to the solenoids 14' and 14" is effected by a 
signal produced by belt deviation detecting means 18 shown in FIG. 3. The 
belt deviation detecting means 18 comprises a pair of feelers 30 (only one 
feeler is shown in FIG. 3) each located in the vicinity of one of opposite 
ends of the follower roller 3 and supported by a shaft 19. Each feeler 20 
comprises a contacting portion 20a kept in contact with the respective 
opposite side edge of the photosensitive endless belt member 1, and a 
light intercepting and admitting portion 20b located opposite the 
contacting portion 20a so as to be able to intercept a light ray emanating 
from a light source 21 or to allow same to pass therethrough. 
The belt deviation detecting means 18 of the aforesaid construction 
operates as follows. When the photosensitive endless belt member 1 
deviates from its normal path of travel and the amount of deviation 
exceeds a predetermined level, the feeler 20 located at the end of the 
follower roller 3 at which deviation of the photosensitive endless belt 
member 1 takes place is moved to allow a light beam emanating from the 
photointerrupter 21 to be interrupted or admitted by the light 
interrupting and admitting section 20b, to thereby turn on the 
phototinterrupter 21. For example, if the photointerrupter 21 located at 
the end of the follower roller 3 located in the plane of FIG. 2 is turned 
on, then the solenoid 14" is energized and the end of the follower roller 
3 located in the plane of FIG. 2 becomes higher than the opposite end 
thereof. Conversely, if the photointerrupter 21 located at the end of the 
follower roller 3 disposed opposite the end located in the plane of FIG. 2 
is turned on, then the solenoid 14' is energized and the end of the 
follower roller 3 located in the plane of FIG. 2 becomes lower than the 
opposite end thereof. 
By using the correction device of the aforesaid construction, it is 
possible to positively detect any deviation of the photosensitive endless 
belt member 1 from its normal path of travel and make it move in the 
predetermined path of travel, so that the problems referred to hereinabove 
which are caused by deviation of the belt member 1 can be obviated. 
However, the belt deviation detecting means 18 would suffer the 
disadvantage that when the follower roller 3 is displaced in such a manner 
that the end of the roller 3 opposite the end thereof in the plane of FIG. 
2 moves to a higher elevation, the gap between the corona discharger 7 and 
the side edge of the photosensitive endless belt member 1 at the opposite 
end of the follower roller 3 might become too large. Thus even if 
discharging is effected by means of the corona discharger 7, the 
transfer-printing sheet 9 might not be brought into contact with the 
surface of the photosensitive endless belt member 2. More specifically, if 
the clearance between the corona discharger 7 and the photosensitive 
endless belt member 1 becomes too large, a reaction offered by the 
firmness of the transfer-printing sheet 9 and other factors to the 
electrostatic force generated by the discharging effected by the corona 
discharger 7 and tending to force the transfer-printing sheet 9 against 
the surface of the photosensitive endless belt member 1 might overcome the 
electrostatic force, with a result that the transfer-printing sheet 9 
might be prevented from coming into contact with the surface of the 
photosensitive endless belt member 1 to a satisfactory degree. When this 
phenomenon occurs, it would be difficult to positively print the toner 
image by transfer-printing on the transfer-printing sheet 9 so that the 
image formed by transfer-printing would not be clearly defined and become 
blurred. This fogging phenomenon is more marked when the firmness of the 
transfer-printing sheet is higher. 
SUMMARY OF THE INVENTION 
This invention has been developed for the purpose of obviating the 
aforesaid disadvantages of the prior art. Accordingly, the invention has 
as its object the provision of a recording system which is capable of 
eliminating the occurrence of a phenomenon of fogging which might 
otherwise occur when transfer-printing is performed by using the belt 
deviation correction device of the type which relies on a displacement of 
one end of the follower roller constructed as a displacing roller. 
The aforesaid object is accomplished according to the invention by 
providing, in a recording system of a construction defined in the preamble 
of the claim, the features comprising a transfer-printing sheet guide 
member located adjacent a corona discharger and having two end portions, 
one end portion corresponding to one end of a displacing roller being 
pivotally supported and the other end portion corresponding to the other 
end of the displacing roller being vertically displaceable, a shield 
formed integrally with the transfer-printing sheet guide member or as a 
separate entity and attached to the transfer-printing sheet guide member 
to provide a guide means of unitary structure and arranged above an edge 
portion of the corona discharger over which a transfer-printing sheet is 
fed, and coupling means for coupling the other end portion of the 
transfer-printing sheet guide member to the other end of the displacing 
roller so that the other end portion of the transfer-printing sheet guide 
member can be moved in a vertical direction as the other end of the 
displacing roller moves in a vertical direction, whereby the shield can at 
least be moved upwardly along with the transfer-printing sheet guide 
member through the coupling means as the displacing roller is moved 
upwardly. 
The recording system according to the invention is capable of positively 
eliminating the occurrence of a phenomenon of fogging when a toner image 
is printed on a transfer-printing sheet by transfer-printing which has 
often occured in the prior art due to the use of a follower roller in the 
form of a displacing roller. Moreover, the movement of the 
transfer-printing sheet guide member taking place conjointly with the 
shield increases the efficiency with which transfer-printing is effected 
when the one end of the displacing roller is moved upwardly. The provision 
of the transfer-printing sheet guide member and the shield as a unitary 
structure eliminates the risk of a sheet jamming. The efficiency with 
which transfer-printing is effected can be further increased by the fact 
that the transfer-printing sheet guide member and the shield define as 
opening for a corona discharge current to flow therethrough from the 
corona discharger. 
The recording system according to the invention can be incorporated not 
only in a laser printer of the electrophotographic type but also in an 
electrophotographic apparatus of other type and an electrostatic recording 
apparatus. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferred embodiments of the invention will now be described by referring 
to the accompanying drawings. 
FIGS. 4 and 5 show, on an enlarged scale, of the follower roller section of 
the recording system comprising one embodiment, in which parts similar to 
those shown in FIGS. 1 and 3 are designated by like reference characters. 
The correction device used in the invention is distinct from the 
correction device shown in FIG. 2 and comprises a solenoid 14 and a 
tension spring 15 which serves as a first tension spring in this 
embodiment, in place of the solenoids 14' and 14" shown in FIG. 2. The 
first tension spring 15 is connected at one end to a pin 23 and at the 
other end to the control arm 12 which is normally urged to move in a 
counterclockwise direction about the pin 13. The reference numerals 16 and 
17 designate stoppers. When the solenoid 14 is de-energized, the control 
arm 12 is brought into abutting engagement with the stopper 17 as shown in 
FIG. 4; when it is energized, the control arm 12 is brought into abutting 
engagement with the stopper 16, so that the control arm 12 can be moved in 
pivotal movement between these two positions. 
The corona discharger 7 comprises, as is known, a casing 26 and a charge 
wire 27. The casing 26 comprises two side walls 26a and 26b, one side wall 
26a located on a side over which a transfer-printing sheet is fed is 
smaller in height than the other side wall 26b, and a shield 28 is located 
above the one side wall 26a. Thus, an upper portion of the other side wall 
26b and a left end portion of the shield 28 define therebetween an opening 
7a for a corona discharge current generated by the corona discharger 7 and 
flowing to the photosensitive endless belt member 1 to flow therethrough. 
The shield 28 is formed integrally with a transfer-printing sheet guide 
member 29 located in close proximity to the right side of the 
transfer-printing corona discharger 7 in FIGS. 4 and 5. Alternatively, the 
shield 28 may be formed as a separate entity and connected to the 
transfer-printing sheet guide member 29 to provide a unitary structure. In 
this case, the shield 28 is connected to the guide member 29 in such a 
manner that there is no difference in vertical height at least between 
upper surfaces of the shield 28 and guide member 29. The shield 28 and 
member 29 constitute guide means. As shown in FIG. 6, the guide member 29 
is pivotally supported at one end portion thereof corresponding to one end 
of the follower roller 3 through a pin 33 by a support plate 32 secured to 
side plates 30 and 31 and has an aperture 34 formed at the other end 
portion thereof corresponding to the other end of the follower roller 3 
for loosely receiving a regulating pin 35 secured to the support plate 32. 
That is, the guide plate 32 is arranged in such a manner that the end 
thereof in the planes of FIGS. 4 and 5 can be displaced vertically and the 
opposite end is supported for pivotal movement, as is the case with the 
follower roller 3. The magnitude of pivotal movement of the guide member 
29 may vary depending on a gap C' formed between the aperture 34 and the 
pin 35. The guide member 29 has a guide surface 29a the right end thereof 
being lower than the right end by C'/2 (half of the gap C') when the 
regulating pin 35 abuts against an upper edge 34a of the aperture 34 
designated by a solid line in FIG. 6 and a left end of the guide surface 
29a becomes higher than a right end thereof by a magnitude substantially 
equal to C'/2 (half of the gap C') when the regulating pin 35 abuts 
against a lower edge 34b of the aperture 34 designated by an irregularly 
broken line in FIG. 6. A downwardly extending arm 36 is formed integrally 
with the guide member 29 at the other end thereof for abutting contact at 
its lower end with an intermediate lever 39 as presently to be described. 
The gap C' is set at about 1.5 mm. The downwardly extending arm 36 has 
been described as being formed integrally with the guide member 29. 
However, the invention is not limited to this construction of the arm 36 
and it may be formed separately from the guide member 29 and connected 
thereto to provide a unitery structure. 
Referring to FIGS. 4 and 5 again, the control arm 12 includes an actuating 
arm 37 formed integrally with the control arm 12 and extending from a 
portion thereof slightly below a central portion in a horizontal 
direction. The actuating arm 37, which may be formed as a separate entity 
and connected to the control arm 12, has a pin 38 secured to its forward 
end. The intermediate lever 39 pivotally supported by a shaft 40 is 
interposed between the pin 38 and the arm 36. The intermediate lever 39 
which is substantially in the form of a letter L includes a downwardly 
extending portion that can be brought at its right side edge into abutting 
engagement with the pin 38 and a rightwardly extending portion having an 
upwardly protruding rightmost end portion that can be brought into 
abutting engagement with the lower end of the arm 36 as described 
hereinabove. Resilient means in the form of a second tension spring 42 is 
connected at one end to a pin 41 and at the other end to the intermediate 
lever 39 so that the intermediate lever 39 is normally urged by the 
biasing force of the second tension spring 42 to move in a 
counterclockwise direction about the shaft 40. Resilient means in the form 
of a third tension spring 43 is connected at one end to the pin 41 and at 
the other end to a tongue 36a attached to the arm 36, so that the guide 
member 29 is normally urged by the biasing force of the third tension 
spring 43 to move in a counterclockwise direction about the pin 33. In 
this embodiment, the intermediate lever 39, second tension arm 42 and 
third tension arm 43 constitute coupling means coupling the guide member 
29 to the control arm 12 so that the guide member 29 can be displaced in 
accordance with the displacement of the control arm 12. 
The embodiment of the recording system constructed as aforesaid operates as 
follows. Assume that the solenoid 14 is energized. Then the control arm 12 
is kept in abutting engagement with the stopper 16, as shown in FIG. 5. 
When the control arm 12 is in this position, the pin 38 presses against 
the intermediate lever 39 against the biasing force of the second tension 
spring 42, and the guide member 29 is kept by the biasing force of the 
third tension spring 43 in a position in which the regulating pin 35 is 
positioned against the upper edge 34a of the aperture 34. The end of the 
follower roller 3 located in the plane of FIG. 5 is disposed in a position 
lower than the position of the opposite end of the follower roller 3, so 
that the photosensitive endless belt member 1 will tend to shift gradually 
toward the end of the follower roller 3 located in the plane of FIG. 5 and 
deviate from its normal path of travel. When the amount of deviation of 
the photosensitive endless belt member 1 from its normal path of travel 
exceeds a predetermined level, such deviation is detected by the detecting 
means 18 which generates a signal to de-energize the solenoid 14. 
Upon de-energization of the solenoid 14, the control arm 12 is moved in the 
counterclockwise direction about the pin 13 by the biasing force of the 
first tension spring 15, into a position in which it abuts against the 
stopper 17. As the control arm 12 moves as aforesaid, the pin 38 of the 
actuating arm 37 shifts rightwardly, so that the intermediate lever 39 is 
moved in pivotal movement about the shaft 40 in the counterclockwise 
direction by the biasing force of the second tension spring 42. Thus the 
intermediate lever 39 is brought into abutting engagement with the arm 36 
and moves same upwardly, to keep the guide member 29 in a position in 
which the lower edge 34b of the aperture 34 is positioned against the 
regulating pin 35 (FIG. 4). Meanwhile the follower roller 3 displaced by 
the pivotal movement of the control arm 12, so that the end of the 
follower roller 3 located in the plane of FIG. 4 is disposed in a position 
higher than the position of the opposite end of the follower roller 3. 
Therefore, the clearance between the corona discharger 7 and the 
photosensitive endless belt number 1 becomes too large, and if this 
condition is allowed to exist, the phenomenon of fogging of the 
transfer-printed image would occur due possibly to insufficient contact 
between the transfer-printing sheet and the photosensitive endless belt 
member 1. In the present invention, however, the guide member 29 coupled 
to the control arm 12 is displaced simultaneously as the control arm 12 
moves in pivotal movement as aforesaid and the end of the guide member 29 
located in the plane of FIG. 4 moves to a position higher than the 
position of the opposite end guide member 29. Since the shield 28 is 
unitary with the guide member 29, the end of the shield 28 in the plane of 
FIG. 4 moves to a position higher than the position of the opposite end of 
the shield 28. Even if such condition exists, it is possible to keep the 
clearance between the photosensitive endless belt member 1 and the guide 
means constituted by the guide member 29 and shield 28 at a desired level. 
This makes it possible to positively bring the transfer-printing sheet 9 
into contact with the surface of the photosensitive endless belt member 1 
when transfer-printing is carried out. More specifically, when 
transfer-printing is performed, the transfer-printing sheet 9 is guided by 
the guide means constituted by the guide member 29 and shield 28 and moves 
through a position which is close to the surface of the photosensitive 
endless belt member 1. Thus, even if the photosensitive endless belt 
member 1 is spaced apart a large distance from the corona discharger 7, 
the transfer-printing sheet 9 can be readily brought into contact with the 
surface of the photosensitive endless belt member 1. If the guide member 
29 were separated from the shield 28, the leading end of the 
transfer-printing sheet 9 might enter the gap separating the guide member 
29 from the shield 28, thereby causing a jam of transfer-printing sheet to 
occur. In the invention, the shield 28 is integral with the guide member 
29 and there is no difference in vertical level between their top 
surfaces, so that the risk of the aforesaid jamming occurring in the 
recording system according to the invention can be avoided. 
As the recording operation is performed while the recording system is in 
the condition shown in FIG. 4, the photosensitive endless belt member 1 
will gradually shift toward the end of the follower roller 3 opposite the 
end thereof in the plane of FIG. 4. When the amount of deviation of the 
belt member 1 exceeds the predetermined level, it is detected by the 
detecting means and the solenoid 14 is energized. Thus the control lever 
12 is moved in pivotal movement in the clockwise direction in FIG. 4, so 
that the follower roller 3 is displaced in a manner to bring the position 
of its end located in the plane of FIG. 4 to a lower level than the 
position of the opposite end. At the same time, the guide member 29 is 
also displaced in a manner to bring the position of its end located in the 
plane of FIG. 4 to a lower level than the position of the opposite end, by 
the biasing force of the third tension spring 43 as the intermediate lever 
39 moves pivotally in the clockwise direction. Thus, the follower roller 
section of the recording system is restored to the condition shown in FIG. 
5. 
In the recording system of the aforesaid construction according to the 
invention, damage to the photosensitive endless belt member 1 is avoided 
by allowing the belt member 1 to deviate from its normal path of travel in 
a predetermined allowable range alternately on opposite ends of the 
follower roller 3, and the occurrence of fogging in transfer-printed 
images is prevented which might be caused by an increase in the clearance 
between the photosensitive endless belt member 1 and the corona discharger 
7. Moreover, the construction in which the guide member 29 and the shield 
28 are formed integrally to provide guide means is conducive to prevention 
of jamming of the transfer-printing sheet 9. In the event that the shield 
28 for the corona discharger 7 is formed integrally with the side wall 26a 
of the casing 26 and stationary, the value of the discharge current which 
is about 19-20 .mu.A when the end of the follower roller 3 located in the 
plane of FIGS. 4 and 5 is displaced downwardly would be reduced to about 
15 .mu.A when the clearance between the opening 7a of the corona 
discharger 7 and the surface of the photosensitive endless belt member 1 
increases as a result of an upward displacement of the end of the follower 
roller 3 located in the plane of FIGS. 4 and 5. In the recording system 
according to the invention, however, when one end of the follower roller 3 
is displaced upwardly, the corresponding end of the shield 28 is also 
upwardly displaced, to thereby prevent the clearance between the opening 
7a of the corona discharger 7 and the surface of the photosensitive 
endless belt member 1 from increasing. Thus the drop in the value of the 
discharge current only drops to about 18 .mu.A and no marked reduction 
occurs in the efficiency with which transfer-printing is carried out. 
In the recording system according to the invention, the guide means 
constituted by the shield 28 and the guide member 29 is disposed relative 
to the parts in its vicinity in such a manner that when the bent between 
the guide member 29 and the shield 28, the forward end of an upper 
conveyor guide plate 44 and the lowermost portion of the follower roller 3 
are designated by G, E and F respectively, G is disposed below the 
straight line l connecting E and F together as shown in FIG. 7, even when 
the end of the follower roller 3 located in the plane of FIG. 7 is 
displaced downwardly. By this arrangement, the leading end of the 
transfer-printing sheet 9 remains held between a pair of fixing rollers, 
and the fluttering of the transfer-printing sheet 9 can be minimized when 
the trailing end of the sheet 9 clears the point E. Thus a reduction in 
the efficiency of transfer-printing can be avoided. 
FIGS. 8-10 show another embodiment of the recording system in conformity 
with the invention, in which guide means 45 located rightwardly of the 
corona discharger 7 in adjacent relation comprises a guide member 46, and 
bearing guide members 47 each secured to one of opposite ends of the guide 
member 46. Support members 48 are each joined as by spot welding to one of 
the bearing guide members 47. As shown in FIG. 8, the guide member 46 is 
downwardly inclined at its right end portion and its left end portion is 
extended as fas as the discharging zone of the corona discharger 7 to 
facilitate guiding to a transfer-printing position of the 
transfer-printing sheet fed in the direction of an arrow B. Stated 
differently, the corona discharger 7 is constructed such that a discharge 
current flows through an opening defined by a forward end of a left side 
wall of its casing and a left end of the guide member 46. 
The bearing guide member 47 are each in the form of a rectangular plate 
arranged to have its major dimension located horizontally and in contact 
at a top surface with an outer peripheral surface of one of the bearings 
3a supporting the follower roller 3 at opposite ends thereof. Each bearing 
guide member 47 is formed with an inclined surface 47a at its upper right 
end corner. 
The support members 48 are each formed of a plate bent substantially in the 
form of a letter U standing on its side and comprise an upper plate 
portion 49, a side plate portion 50 and a lower plate portion 51. The 
upper plate portion 49 has a lug 52 attached thereto for having one of the 
bearing guide members 47 secured thereto. The side plate portion 50 is 
formed with an aperture 54 which is larger in size than the amount of 
movement of the guide means 45 and has connected thereto a support 53 for 
supporting the corona discharger 7 for movement, as shown in FIGS. 8 and 
9. A stepped screw 55 threadably connected to the rails 53 is loosely 
fitted in the aperture 54, so that the guide means 45 can be moved 
vertically as the stepped screw 53 is moved in the aperture 54. The lower 
plate portion 51 is formed with an aperture 56 which receives a stud 57 
secured to the support 53. Resilient means in the form of a compression 
spring 58 is mounted between a head of the stud 57 and the lower plate 
portion 51 to normally urge the guide means 45 to move upwardly by its 
biasing force. This ensures that the bearing guide member 47 are brought 
into contact with the respective bearings 3a for the follower roller 3, so 
as to keep a spacing C between a top surface of the guide member 46 and 
the photosensitive endless belt member constant at all times. 
The embodiment of the recording system constructed as aforesaid in 
conformity with the invention operates as follows. Assume that the 
solenoid 14 is energized. This brings the control arm 12 into abutting 
engagement with the stopper 16 as shown in FIG. 9. When the control arm 12 
is in this condition, the end of the follower roller 3 located in the 
plane of FIG. 9 is disposed in a position lower than that of the opposite 
end of the follower roller 3 and consequently the spacing between the 
photosensitive endless belt member 1 and the corona discharger 7 is 
reduced on the side edge portion of the belt 1 corresponding to the end of 
the follower roller 3 located in the plane of FIG. 9. The guide means 45 
follows up the follower roller 3 and is located in an inclined position. 
Thus, as the biasing guide members 47 are brought into pressing contact 
with the bearings 3a for the follower roller 3 and the end of the follower 
roller 3 located in the plane of FIG. 9 is displaced downwardly as 
aforesaid, the guide member 46 of the guide means 45 is also displaced 
downwardly at an end thereof corresponding to the end of the follower 
roller 3 in the plane of FIG. 9. Therefore, the spacing C between the top 
surface of the guide member 46 of the guide means 45 and the 
photosensitive endless belt member 1 can be kept at a predetermined level. 
If the follower roller 3 is displaced as aforesaid, the photosensitive 
endless belt member 1 gradually deviates from its normal path of travel 
and shifts toward the end of the follower roller 3 in the plane of FIG. 9 
which is downwardly displaced, as recording operations are repeatedly 
performed. When this deviation exceeds a predetermined allowable range, it 
is detected by the detecting means 18 shown in FIG. 3 which produces a 
signal to de-energize the solenoid 14. 
Upon de-energization of the solenoid 14, the control arm 12 is pivotally 
moved in a counterclockwise direction about the shaft 13 by the biasing 
force of the tension spring 15 into abutting engagement with the stopper 
17, as shown in FIG. 8. As the control arm 12 moves in pivotal movement as 
aforesaid, the follower roller 3 is displaced so that the end thereof 
located in the plane of FIG. 8 is displaced to a position which is higher 
than the position of the opposite end of the follower roller 3. At the 
same time, the guide means 45 is also displaced through the compression 
springs 58 in such a manner that the end thereof corresponding to the end 
of the follower roller 3 located in the plane of FIG. 8 is displaced to a 
position higher than the position of the opposite end thereof. At this 
time, the bearing guide members 47 are kept in a position in which they 
are in pressing engagement with the respective bearings 3a for the 
follower roller 3 by virtue of the fact that the follower roller 3 is 
indirectly held in place by the stopper 17. Thus, the spacing C between 
the top surface of the guide member 46 of the guide means 45 and the 
photosensitive endless belt member 1 can be kept at the predetermined 
level. 
In this way, the clearance C between the photosensitive endless belt member 
1 and the guide means 45 can be kept constant at all times. Thus, even if 
the gap between the corona discharger 7 and the photosensitive endless 
belt member 1 becomes too great, it is possible to let the 
transfer-printing sheet 9 pass through a position close to the 
photosensitive endless belt member 1. This is conductive to prevention of 
the occurrence of fogging in transfer-printed images.