Sheet convey apparatus

The present invention provides a recording apparatus comprising convey means for conveying a sheet in a predetermined convey direction, a pair of rollers arranged downstream of the coney means in the convey direction for conveying the sheet in the convey direction or in a reverse direction by rotation in a forward direction or in a reverse direction, and control means for controlling the convey means and the pair of rollers. The control means controls these elements in such a manner that, after a sheet conveyed by the convey means is conveyed in the convey direction by a predetermined amount by the pair of rollers, the pair of rollers are rotated in the reverse direction while applying a conveying force in the convey direction to the sheet using the convey means, thereby conveying the sheet in the reverse direction until the sheet passes through a nip formed between the pair of rollers.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a sheet convey apparatus for conveying a 
sheet to a recording portion or a reading portion in a printer, a 
typewriter, a copying machine, a facsimile machine and the like, and more 
particularly, it relates to a sheet convey apparatus wherein a sheet can 
be fed in a direction perpendicular to a generatrix of a convey roller 
without skew-feed of the sheet and with high accuracy. 
2. Related Background Art 
As shown in FIG. 27, in a conventional recording apparatus 250, when a 
sheet P is set, the sheet P is rested on an inclined sheet supply tray 
251, and then a knob 252 is rotated to wind the sheet P around a platen 
253 once, and then the knob 252 is rotated reversely to disengage the 
sheet P from a nip between the platen 253 and a pinch roller 255. As a 
result, a leading or tip end of the sheet P is abutted against the nip 
between the platen 253 and the pinch roller 255 by the weight of the 
sheet, thereby positioning the sheet along the nip. Then, when the platen 
253 is rotated normally, the sheet P is reliably conveyed in a direction 
perpendicular to the generatrix of the platen 253. The above method 
usually is used in conventional techniques. 
However, in the conventional case shown in FIG. 27, after the sheet P is 
positioned along the nip between the platen 253 and the pinch roller 255, 
when the sheet is re-entered into the nip by rotating the knob 252 
normally, since the urging force for abutting the tip end of the sheet P 
against the nip depends upon the weight of the sheet P itself, if a sheet 
supply direction becomes a direction near a horizontal direction, the 
urging force for abutting the sheet P against the nip is extremely 
weakened or eliminated, with the result that the sheet P cannot be 
re-entered into the nip. 
Next, in the Japanese Patent Publication No. 62-38261, as shown in FIG. 28, 
a sheet P supplied from a pick-up roller 261 of a sheet supply device to a 
drive roller 262 is fed reversely until a tip end of the sheet passes 
through a nip of the drive roller 262, thereby forming a loop in the sheet 
P between the pickup roller 261 and the drive roller 262, so that the tip 
end of the sheet P is abutted against the nip of the drive roller 262. 
Thereafter, the sheet P is fed out by rotating the drive roller normally. 
In the conventional case shown in FIG. 28, the urging force for abutting 
the tip end of the sheet against the nip of the drive roller 262 is not 
influenced by the sheet supply direction since such urging force depends 
upon the repelling force of the sheet P for restoring the looped sheet to 
its original flat form. However, since a loop must be formed in the rigid 
sheet P, a thick sheet cannot be used, and since a space and a convey path 
length sufficient to permit formation of the loop must be provided, it is 
difficult to make the apparatus small-sized. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a sheet convey apparatus 
wherein a sheet can be conveyed correctly in a sheet supply direction even 
if an insertion direction for the sheet is skew and even when a thick 
sheet is supplied. 
Another object of the present invention is to provide a sheet convey 
apparatus wherein a plurality of sheets (which are one of various kinds of 
sheets such as a thin sheet, thick sheet, post card, envelope, resin film 
or the like) can be separated one by one, and each separated sheet is 
passed through a main roller in a condition that a tip end of the 
separated sheet is positioned along the generatrix of the main roller, and 
the sheet is conveyed to a predetermined position with high accuracy 
(Incidentally, in the conventional techniques, since the usable sheets are 
limited to flexible ones, the kinds of the sheets are limited). 
Another object of the present invention is to provide a sheet convey 
apparatus which can be made small-sized by reducing the large space and 
convey path length required for forming a loop in a sheet in the 
conventional techniques.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 and 2 show a first embodiment of the present invention, where FIG. 
1 is a sectional view of a recording apparatus including a sheet convey 
apparatus according to the first embodiment, and FIG. 2 is a perspective 
view of a sheet convey mechanism of the recording apparatus. 
In FIG. 1, a recording apparatus 1 comprises an outer cover 2 and a sheet 
supply deck 3, and the cover 2 is provided with a sheet supply opening 2a 
and a sheet discharge opening 2b, and the sheet supply deck 3 is provided 
with a paper guide 3a. A sheet P is inserted from the sheet supply opening 
2a and is discharged from the discharge opening 2b. 
Inside a plurality of side plates 4 of the recording apparatus 1, there are 
arranged a main roller 5 for conveying the sheet, a support shaft 6 on 
which the main roller 5 is secured, a guide plate 7 for guiding the sheet, 
a sensor S1 disposed in an opening formed in the guide plate 7, a platen 8 
for establishing a print position for the sheet, a hold-down plate 9 
pivotally mounted around a fulcrum 9a and biased by a spring 10 toward the 
main roller 5, hold-down rollers 11 rotatably mounted on a free end 
portion of the hold-down plate 9 and adapted to urge the sheet against the 
main roller 5, a carriage 13 shiftable along a plurality of guide shafts 
12 in a widthwise direction of the sheet, and a recording head 14 mounted 
on the carriage 13 and adapted to perform printing in response to image 
information. 
In place of the hold-down rollers 11 mounted on the free end of the 
hold-down plate 9, the free end itself of the hold-down plate 9 may be 
used as a means for urging the sheet against the main roller 5. Further, 
in this case (having no hold-down roller), the hold-down plate may be 
formed from a thin plate having the spring feature such as stainless 
steel. 
Further, within the recording apparatus 1, there are arranged a support 
shaft 15, a ring 16 secured to the support shaft 15, pins 16a, 16b 
protruded from a peripheral surface of the ring 16, auxiliary rollers 17 
rotatably supported by the support shaft 15 and having a pin 17a at its 
side surface, a spring 18 extending between the pins 16a and 17a, a pinch 
roller 20 rotatably supported by a spring plate 19 and urged against the 
auxiliary rollers 17, and a sensor S2 disposed in the proximity of the 
sheet supply opening 2a. A peripheral surface of the auxiliary roller 17 
is constituted by high friction material such as rubber. 
In FIG. 2, a motor M1 serves to rotate the main roller 5 via a motor gear 
21, a two-stage gear 22 and a main roller gear 23 secured to the shaft 6 
in response to a control signal from a controller (control device) 24. A 
rotational force of the motor M1 is transmitted to the shaft 15 via a gear 
25 meshed with the main roller gear 23, a gear 26 and a one-way clutch 28. 
The one-way clutch 28 can transmit forward rotation (in a direction shown 
by the arrow 30) of a gear 27 in response to forward rotation of the main 
roller 5 in a direction shown by the arrow 29 (normal convey direction for 
the sheet P) to the shaft 15, but does not transmit reverse rotation (in a 
direction shown by the arrow 32) of the gear 27 in response to reverse 
rotation of the main roller 5 in a direction shown by the arrow 31 
(reverse convey direction for the sheet P) to the shaft 15. A tip end of a 
ratchet lever 34 mounted around a shaft 34a and biased by a biasing force 
of a spring 35 in an anti-clockwise direction is abutted against a 
peripheral surface of a ratchet wheel 33 secured to the support shaft 15 
and having saw-shaped teeth on its peripheral surface. The ratchet lever 
34 permits forward rotation of the ratchet wheel 33 in a direction shown 
by the arrow 30, but prevents reverse rotation of the ratchet wheel in a 
direction shown by the arrow 32. 
When a movable bar 37 is shifted upwardly by a plunger 36 in response to a 
control signal from the controller 24, since the ratchet lever 34 
contacted with a lower bent portion of the movable bar 37 is rotated in a 
clockwise direction in opposition to the force of the spring 35, the 
ratchet lever is disengaged from a tooth of a ratchet wheel 33, thereby 
permitting the clockwise rotation of the ratchet wheel 33. 
Next, a sheet convey operation of the sheet convey apparatus according to 
the first embodiment will be explained with reference to FIGS. 1 and 2. 
When a sheet P is inserted from the sheet supply opening 2a along the sheet 
supply deck 3 and paper guide 3a, a tip end of the sheet is detected by 
the sensor S1. On the basis of the detection of the sensor, the controller 
24 energizes the motor M1 to rotate the main roller 5 in the normal sheet 
convey direction shown by the arrow 29. 
The rotation of the main roller 5 is transmitted to the gear 27 (rotation 
in the direction shown by the arrow 30) via the gears 25, 26. When the 
gear 27 is rotated in the direction shown by the arrow 30, since the 
one-way clutch 28 connects gear 27 to the support shaft 15, the support 
shaft 15 is also rotated in the same direction. The rotation of the 
support shaft 15 is transmitted to the auxiliary rollers 17 via the ring 
16 secured to the support shaft 15, the pin 16a protruded from the ring 
16, the pin 17a formed on the side surface of the auxiliary rollers 17 and 
the spring 18 connecting between the pins 16a, 17a, thereby rotating the 
auxiliary rollers 17 in the direction shown by the arrow 30. 
During the above rotation, the pin 17a is always abutted against the pin 
16b with a predetermined force by the spring 18. By rotating the auxiliary 
rollers 17 in the direction shown by the arrow 30, the sheet P is conveyed 
toward that side of the apparatus; meanwhile, when the tip end of the 
sheet is detected by the sensor S1, the controller 24 controls the motor 
M1 to feed out the tip end of the sheet by a length L shown in FIG. 1. 
Now, a protruded amount N of the tip end of the sheet from the nip between 
the main roller 5 and the hold-down rollers 11 will now be explained with 
reference to FIG. 9, which is a plan view of the sheet convey portion of 
the recording apparatus of FIG. 1. 
When a sheet P is skew-fed as shown by P.sub.1, the protruded amount N at 
the left side differs from that at the right side, and there is the 
following difference W between the left protruded amount T and the right 
protruded amount U: 
EQU W=T-U 
When it is assumed that the difference W is a skew amount, if the amount of 
the difference W is great, the protruded amount N must be increased 
accordingly; however, the protruded amount is limited due to the size of 
the sheet supply opening 2a. 
The means 3a, 3b for regulating lateral edges of the sheet is effective to 
regulate the protruded amount difference W. When it is assumed that the 
protruded amount difference W is 3 mm and the margin of slip between the 
sheet P and the convey rollers is 2 mm, the protruded amount N becomes as 
follows: 
EQU N=3+2=5. 
When the tip end of the sheet is protruded by the amount N, the main roller 
5 is rotated in the sheet reverse convey direction shown by the arrow 31 
under the control of the controller 24 (see FIG. 2). The rotational amount 
of the main roller 5 is greater than at least the protruded amount N, and, 
desirably, is (2.times.N)-(3.times.N). 
In response to the rotation of the main roller 5 in the direction shown by 
the arrow 31, the gear 27 is rotated in the direction shown by the arrow 
32. However, this rotation is not transmitted to the support shaft 15 by 
the action of the one-way clutch 28. 
In synchronism with the reverse movement of the sheet P, the auxiliary 
rollers 17 are rotated in the direction shown by the arrow 32. On the 
other hand, although the pin 17a is also rotated, since the support shaft 
15 cannot be rotated in the direction shown by the arrow 32 by the action 
of the ratchet wheel 33 and the ratchet lever 34, the pin 16a is not 
rotated, with the result that the rotation of the auxiliary rollers 17 
results in only the extension of the spring 18. Since the tension force of 
the spring 18 acts to rotate the auxiliary rollers 17 in the direction 
shown by the arrow 30, during this action, the auxiliary rollers 17 always 
give a normal direction conveying force to the sheet. Further, since the 
plurality of auxiliary rollers 17 are rotatably mounted on the support 
shaft 15 so that they can be rotated independently, the auxiliary rollers 
17 can be rotated independently even if the shifting amounts of the sheet 
differ from each other in the widthwise direction of the sheet. 
In FIG. 9, if a sheet P is conveyed reversely from the condition P.sub.1, 
first of all, the right protruded amount U is conveyed to the nip (contact 
position) between the main roller 5 and the hold-down rollers 11, and when 
the right end passes through the contact position, the right end is not 
further shifted reversely. At the same time, although the left protruded 
amount T is conveyed to the nip, since U&lt;T, the left end is conveyed to 
the contact position later than the right end. As a result, the right and 
left ends of the sheet P are stopped along the contact position to 
establish a condition P.sub.2. The biasing force of the spring 18 is 
selected so that the tip end of the sheet is not flexed in the condition 
P.sub.2. The condition P.sub.2 is referred to as a sheet registration 
start position. From this condition, when the main roller 5 is rotated in 
the direction shown by the arrow 29 by a predetermined amount by the 
controller 24, by the normal direction conveying force of the auxiliary 
rollers 17, the left and right tip ends of the sheet P enter into the 
contact position along the contact position and then are conveyed to a 
record position of the recording head 14 without any skew-feed and with 
high accuracy. 
Next, in response to a record signal, the sheet P is fed normally by a 
predetermined amount and then the carriage 13 is shifted reciprocally in 
the widthwise direction, thereby effecting one line recording by the 
recording head 14. By repeating such operations, one page recording of the 
sheet is effected. During the recording, when a special record mode is 
performed (for example, when the recording head 14 is returned to the 
previously recorded line and recording is effected again on that line), 
the controller 24 energizes the plunger 36 to permit the rotation of the 
ratchet wheel 33 in the direction shown by the arrow 32. At the same time, 
when the main roller 5 is rotated in the direction shown by the arrow 31 
by a predetermined amount in order to return the sheet P to the previously 
recorded line, since the auxiliary rollers 17 do not generate the normal 
direction conveying force and are freely rotated by the reverse movement 
of the sheet P, the sheet P is returned with the convey accuracy of the 
main roller 5. Thereafter, when the main roller 5 is rotated normally 
again, the controller 24 stops the operation of the plunger, thus 
restoring the original condition. 
As another method for controlling the plunger 36, when the sheet P reaches 
the record position of the recording head 14, the plunger 36 may be driven 
to lift the lever 34 and the plunger 36 may be stopped at the time when 
the recording operation is completed. 
When a trailing end of the sheet P is detected by the sensor S1, the main 
roller 5 feeds the sheet by a predetermined amount for recording under the 
control of the controller 24. After the last feeding of the sheet is 
completed, the main roller 5 is rotated by a predetermined amount, thereby 
discharging the sheet from the discharge opening 2b. 
When the whole sheet feeding amount for the recording previously stored on 
the basis of a command from a computer is completed, the controller 24 
rotates the main roller 5 to discharge the sheet, even without the 
detection signal of the sensor S1 representative of the fact that the 
trailing end of the sheet is detected. After the sheet is discharged by 
the main roller 5, the controller 24 sets the recording apparatus 1 to the 
initial condition when the signal from the sensor S1 indicates the absence 
of a sheet. On the other hand, if the signal from the sensor indicates the 
presence of a sheet, the controller judges the fact that a poor sheet 
convey condition has occurred, and emits an alarm signal via display means 
or sound means. 
Next, a second embodiment of the present invention will be explained with 
reference to FIGS. 3 and 4. 
FIG. 3 is a sectional view of a recording apparatus according to the second 
embodiment, and FIG. 4 is a schematic perspective view of a sheet convey 
mechanism of the recording apparatus. Incidentally, in FIGS. 3 and 4, the 
same structural and functional elements as those of FIGS. 1 and 2 are 
designated by the same reference numerals. 
In FIG. 3, the recording apparatus 1 comprises an outer cover 2 and a sheet 
supply deck 3, and the cover 2 is provided with a sheet supply opening 2a 
and a sheet discharge opening 2b, and the sheet supply deck 3 is provided 
with a paper guide 3a. A sheet P is inserted from the sheet supply opening 
2a and is discharged from the discharge opening 2b. Inside a plurality of 
side plates 40 of the recording apparatus 1, there are arranged a main 
roller 5 for conveying the sheet, a support shaft 6 on which the main 
roller 5 is secured, a guide plate 7 for guiding the sheet, a sensor S1 
disposed in an opening formed in the guide plate, a platen 8 for 
establishing a record position for the sheet, a hold-down plate 9 
pivotally mounted around a fulcrum 9a and biased by a spring 10 toward the 
main roller 5, hold-down rollers 11 rotatably mounted on a free end 
portion of the hold-down plate 9 and adapted to urge the sheet against the 
main roller 5, a carriage 13 shiftable along a plurality of guide shafts 
12 in a widthwise direction of the sheet, and a recording head 14 mounted 
on the carriage 13 and adapted to perform printing in response to image 
information. 
Further, within the recording apparatus 1, there are arranged a support 
shaft 41 received in slots 40a formed in the side plates 40 for movement 
to a position 41a shown by broken lines an auxiliary roller 17 secured to 
the support shaft 41 and having a peripheral surface constituted by high 
friction material such as rubber, a directing plate 43 rotatably supported 
around a support shaft 43a and biased by a spring 44 to be urged against 
the auxiliary roller 42 with a predetermined pressure and having an 
abutment surface formed from smooth material, and a sensor S2 disposed in 
an opening formed in the directing plate 43 and in the proximity of the 
sheet supply opening 2a. 
In FIG. 4, a motor M1 serves to rotate the main roller 5 via a motor gear 
21, a two-stage gear 22 and a main roller gear 23 secured to the shaft 6 
in response to a control signal from a controller 24. A rotational force 
of the motor M1 is transmitted to the shaft 41 via a gear 25 meshed with 
the main roller gear 23, a gear 26 and a one-way clutch 28. The one-way 
clutch 28 can transmit forward rotation (in a direction shown by the arrow 
30) of a gear 27 to a shaft 45, but does not transmit reverse rotation (in 
a direction shown by the arrow 32) of the gear 27 to the shaft 45. 
The shaft 45 and the support shaft 41 are interconnected via a universal 
joint 46 which can be freely flexed and can transmit the rotation. 
Further, a plurality of free rollers 47 are rotatably mounted on the 
support shaft 41. A spring 48 having one end connected to one end 41a of 
the support shaft 41 and the other end connected to a hook portion 40b 
provided on the side plate 40 biases the support shaft 41 toward the main 
roller 5 along the slots 40a. 
A tip end of a ratchet lever 34 mounted around a shaft 34a and biased by a 
biasing force of a spring 35 in an anti-clockwise direction is abutted 
against a peripheral surface of a ratchet wheel 33 secured to the support 
shaft 15 and having saw-shaped teeth on its peripheral surface. The 
ratchet lever 34 permits forward rotation of the ratchet wheel 33 in a 
direction shown by the arrow 30, but prevents reverse rotation of the 
ratchet wheel in a direction shown by the arrow 32. 
When a movable bar 37 is shifted upwardly by a plunger 36 in response to a 
control signal from the controller 24, since the ratchet lever 34 
contacted with a lower bent portion of the movable bar 37 is rotated in a 
clockwise direction around the shaft 43a, the ratchet lever is disengaged 
from the tooth of the ratchet wheel 33, thereby permitting rotation of the 
ratchet wheel 33 in the direction shown by the arrow 32. 
Next, a sheet convey operation of the sheet convey apparatus according to 
the second embodiment will be explained with reference to FIGS. 3 and 4. 
When a sheet P is inserted from the sheet supply opening 2a along the sheet 
supply deck 3 and paper guide 3a, a tip end of the sheet is detected by 
the sensor S1. On the basis of the detection of sensor S1, the controller 
24 energizes the motor M1 to rotate the main roller 5 in the normal sheet 
convey direction shown by the arrow 29. The rotation of the main roller 5 
is transmitted to the gear 27 via the gears 23, 25 and 26 to rotate the 
gear 27 in the direction shown by the arrow 30. 
When the gear 27 is rotated in the direction shown by the arrow 30, since 
the one-way clutch 28 connects gear 27 to the shaft 45, the support shaft 
41 is also rotated in the same direction 30 via the universal joint 46. 
The sheet P pinched between the auxiliary roller 42 secured to the support 
shaft 41 and the directing plate 43 is sent to the main roller 5 by the 
rotation of the auxiliary roller 42. The free rollers 47 follow the 
movement of the sheet P and guide the sheet P while holding down the 
sheet. When the tip end of the sheet P is detected by the sensor S1, the 
controller 24 controls the motor M1 to feed out the tip end of the sheet 
by a length L. 
Then, when the controller 24 rotates the main roller 5 in the direction 
shown by the arrow 31 by a predetermined amount, the auxiliary roller 42 
tries to rotate in the direction shown by the arrow 32 in response to the 
reverse movement of the sheet P, but the auxiliary roller cannot be 
rotated due to the action of the ratchet lever 34. Accordingly, the 
auxiliary roller 42 is shifted away from the roller 5 while being stopped 
and while extending the spring 48. During this shifting movement, the 
auxiliary roller 42 continues to apply a conveying force to the sheet P in 
the normal (forward) convey a direction with the aid of the extended 
spring 48. 
During the reverse rotation of the main roller 5, when the left and right 
tip ends of the sheet P are passed by a nip (contact position) between the 
main roller 5 and the hold-down rollers 11, the left and right tip ends of 
the sheet P are maintained along the contact position by the shifting 
force of the auxiliary roller 42. The biasing force of the spring 48 is 
selected so that the tip end of the sheet is not flexed by the shifting 
force of the auxiliary roller. 
After the predetermined amount of reverse rotation of the main roller 5, 
when the main roller 5 is rotated normally by a predetermined amount from 
the above condition which is referred to as a sheet registration start 
position, the left and right tip ends of the sheet P pass through the 
contact position along the contact position by the shifting force of the 
auxiliary roller 42 and are further conveyed to a record position of the 
recording head 14 without skew-feed and with high accuracy. Thereafter, 
since the operation from the recording to the discharge of the sheet is 
the same as the first embodiment, the explanation thereof will be omitted. 
Next, a third embodiment of the present invention will be explained with 
reference to FIGS. 5 and 6. 
FIG. 5 is a sectional view of a recording apparatus according to the third 
embodiment, and FIG. 6 is a schematic perspective view of a sheet convey 
mechanism of the recording apparatus. Incidentally, in FIGS. 5 and 6, the 
same structural and functional elements as those of FIGS. 1 and 2 are 
designated by the same reference numerals. 
In FIG. 5, the recording apparatus 1 comprises an outer cover 2 and a sheet 
supply deck 3, and the cover 2 is provided with a sheet supply opening 2a 
and a sheet discharge opening 2b, and the sheet supply deck 3 is provided 
with a paper guide 3a. A sheet P is inserted from the sheet supply opening 
2a and is discharged from the discharge opening 2b. Inside a plurality of 
side plates 50 of the recording apparatus 1, there are arranged a main 
roller 5 for conveying the sheet, a support shaft 6 on which the main 
roller 5 is secured, a guide member 51 for guiding the sheet, a sensor S1 
disposed in an opening formed in the guide member 51, a platen 8 for 
establishing a record position for the sheet, a hold-down plate 9 
pivotally mounted around a fulcrum 9a and biased by a spring 10 toward the 
main roller 5, hold-down rollers 11 rotatably mounted on a free end 
portion of the hold-down plate 9 and adapted to urge the sheet against the 
main roller 5, a carriage 13 shiftable along a plurality of guide shafts 
12 in a widthwise direction of the sheet, and a recording head 14 mounted 
on the carriage 13 and adapted to perform printing in response to image 
information. 
Further, within the recording apparatus 1, there are arranged a lever 54 
rotatably mounted on a pin 52 and biased toward a clockwise direction by a 
biasing force of a spring 53, a shaft 55 on which one end of the lever 54 
is pivotally mounted, an auxiliary roller 56 secured to the shaft 55, a 
shaft 57 having both ends rotatably supported by the side plates 50, an 
auxiliary roller 58 secured to the shaft 57, and a sensor S2 disposed in 
the proximity of the sheet supply opening 2a. 
In FIG. 6, a motor M1 serves to rotate the main roller 5 via a motor gear 
21, a two-stage gear 22 and a main roller gear 23 secured to the shaft 6 
in response to a control signal from a controller 24. A rotational force 
of the motor M1 is transmitted to gears 60, 61 via a gear 59 meshed with 
the main roller gear 23. A one-way clutch 62 can transmit forward rotation 
(in a direction shown by the arrow 63) of the gear 60 to the shaft 55, but 
does not transmit reverse rotation (in the reverse direction) of the gear 
60 to the shaft 55. A one-way clutch 64 can transmit forward rotation (in 
a direction shown by the arrow 65) of reverse 61 to the shaft 57, but does 
not transmit the rotation (in the reverse direction) of the gear 61 to the 
shaft 57. 
Since the other end of the shaft 55 is rotatably supported by a lever 68 
rotatably mounted on a shaft 66 of the gear 59 and biased in an 
anti-clockwise direction by a biasing force of a spring 67, a distance 
between the shafts of the gears 59, 60 is kept constant even when the 
levers 54, 68 are rotated. 
When the main roller 5 is rotated in the direction shown by the arrow 29, 
the gear 64 is rotated in the direction shown by the arrow 65 via gears 
23, 59. This rotation is transmitted to the shaft 57 via the one-way 
clutch 64, thereby rotating the auxiliary roller 58 in the direction shown 
by the arrow 65. On the other hand, since rotation of the gear 60 in the 
same rotational direction of the gear 64 is prevented by the one-way 
clutch 62, the shaft 55 is not rotated. However, since the auxiliary 
roller 56 is urged against the auxiliary roller 58 with (or without) the 
interposition of the sheet at a predetermined urging force by the springs 
13, 67, the auxiliary roller 56 is driven by the rotation (in the 
direction shown by the arrow 65) of the auxiliary roller 58 to rotate in 
the direction shown by the arrow 63. In this way, a normal direction 
shifting force is applied to the sheet P by the plurality of auxiliary 
rollers. 
When the main roller 5 is rotated in the direction shown by the arrow 31, 
the gear 60 is rotated in the direction shown by the arrow 63. This 
rotation is transmitted to the shaft 55 via the one-way clutch 62, thereby 
rotating the auxiliary roller 56 in the direction shown by the arrow 63. 
On the other hand, since the rotation of the gear 64 in the same direction 
as the gear 60 is prevented by the clutch 64, the shaft 57 is not rotated; 
but, the auxiliary roller 58 is driven by the rotation of the roller 56 to 
rotate in the direction shown by the arrow 65. In this way, a normal 
direction shifting force is applied to the sheet P by the plurality of 
auxiliary rollers. 
A plurality of free rollers 69 rotatably mounted on the shaft 55 and a 
plurality of free rollers 70 rotatably mounted on the shaft 57 and opposed 
to the free rollers 69 are freely rotated by the shifting movement of the 
sheet P while preventing the sheet from floating. 
When a movable bar 37 is shifted upwardly by a plunger 36 in response to a 
control signal from the controller 24, a lower end of the movable bar 37 
is abutted against a lower surface of a free end of the lever 68, thereby 
rotating the levers 68, 54 in the clockwise direction. By this rotation, 
since the auxiliary rollers 56, 58 are separated from each other, the 
sheet P is shifted only by the conveying force of the main roller 5. 
Next, a sheet convey operation of the sheet convey apparatus according to 
the third embodiment will be explained with reference to FIGS. 5 and 6. 
When the sheet P is inserted from a sheet supply opening 2a along the sheet 
supply deck 3 and paper guide 3a, a tip end of the sheet is detected by 
the sensor S1. On the basis of the detection of the sensor, the controller 
24 energizes the motor M1 to rotate the main roller 5 in the normal sheet 
convey direction shown by the arrow 29. The rotation of the main roller 5 
is transmitted to the shaft 57 via the gears 23, 59, 61 and the one-way 
clutch 64 to rotate the auxiliary roller 58 in the direction shown by the 
arrow 65. By the rotation of the auxiliary roller 58, the tip end of the 
sheet P is conveyed toward the main roller 5. During this conveyance of 
the sheet, when the tip end of the sheet is detected by the sensor S1, the 
controller 24 controls the motor M1 to feed out the sheet by a length L. 
During rotation of the auxiliary roller 58, the auxiliary roller 56 is 
driven by the rotation of the auxiliary roller 58 via the sheet P to 
rotate in the direction shown by the arrow 63. 
Then, when the main roller 5 is rotated in the direction by the arrow 31 by 
a predetermined amount by the controller 24, the rotation (in the 
direction shown by the arrow 63) of the gear 60 is transmitted to the 
auxiliary roller 56 via the clutch 62 to rotate the auxiliary roller 56 in 
the same direction, thereby applying a normal direction conveying force to 
the sheet P. During this rotation of the auxiliary roller 56, the 
auxiliary roller 58 is driven by the rotation of the auxiliary roller 56 
via the sheet P to rotate in the direction shown by the arrow 65. 
During reverse rotation of the main roller 5, when the left and right tip 
ends of the sheet P are passed by a nip (contact position) between the 
main roller 5 and the hold-down rollers 11, the left and right tip ends of 
the sheet P are maintained along the contact position by the shifting 
force of the auxiliary roller 56. The biasing forces of the springs 13, 67 
are selected so that the tip end of the sheet is not flexed by the 
shifting force of the auxiliary roller. 
After a predetermined amount of reverse rotation of the main roller 5, when 
the main roller 5 is rotated normally by a predetermined amount from the 
above condition to a position which is referred to as a sheet registration 
start position, the left and right tip ends of the sheet P pass through 
the contact position along the contact position by the shifting force of 
the auxiliary roller 56 and are further conveyed to a record position of 
the recording head 14 without skew-feed and with high accuracy. 
Thereafter, since the operation from recording to discharge of the sheet 
is the same as the first embodiment, the explanation thereof will be 
omitted. 
Next, a fourth embodiment of the present invention will be explained with 
reference to FIGS. 7 and 8. 
FIG. 7 iS a schematic perspective view of a sheet convey mechanism of a 
recording apparatus according to the third embodiment, and FIG. 8 is a 
sectional view of the recording apparatus. Incidentally, in FIGS. 7 and 8, 
the same structural and functional elements as those of FIGS. 1 and 2 are 
designated by the same reference numerals. 
In FIG. 8, the recording apparatus comprises a body cover 71 having a 
discharge opening 71a. Inside the body cover 71, there are arranged a 
hopper 72 for containing a plurality of sheets K, a paper support 73 for 
holding trailing ends of the sheets, a pressure plate 74 rotatably 
supported by the hopper 72 via a shaft 74a, semi-circular sheet supply 
rollers 76, a support shaft 75 on which the sheet supply rollers 76 are 
secured, and a separating pawl 78 provided on the pressure plate 74. 
Further, there are arranged an auxiliary roller 80 for conveying a sheet 
supplied and separated one by one by the sheet supply rollers 76 and the 
separating pawl 78, a support shaft 79 on which the auxiliary roller 80 is 
secured, a pinch roller 82 rotatably supported by a spring plate 81 and 
urged against the auxiliary roller 80, a guide plate 83 for guiding the 
sheet, a sensor S1 for detecting the movement of the sheet, a platen 8 for 
establishing a record position for the sheet, a main roller 5 for 
conveying the sheet, a support shaft 6 on which the main roller 5 is 
secured, a hold-down plate 9 pivotally mounted around a fulcrum 9a and 
biased by a spring 10 toward the main roller 5, hold-down rollers 11 
rotatably mounted on a free end portion of the hold-down plate 9 and 
adapted to urge the sheet against the main roller 5, a carriage 13 
shiftable along a plurality of guide shafts 12 in a widthwise direction of 
the sheet, and a recording head 14 mounted on the carriage 13 and adapted 
to perform printing in response to image information. A peripheral surface 
of the auxiliary roller 80 is constituted by high friction material such 
as rubber. 
In FIG. 7, a motor M1 serves to rotate the main roller 5 via a motor gear 
21, a two-stage gear 22 and a main roller gear 23 secured to the shaft 6 
in response to a control signal from a controller 84. Further, the 
controller 84 also controls a motor M2, and a rotational force of the 
motor M2 is transmitted to a sheet supply roller gear 88 via a motor gear 
85, a gear 86 and an intermediate gear 87. The sheet supply roller gear 88 
is rotatably mounted on a shaft 75. The rotation of the sheet supply 
roller gear 88 is transmitted to the sheet supply rollers 76 via a one 
revolution spring clutch 89 and the shaft 75. 
In FIG. 10, which is a sectional view of the one revolution spring clutch 
89, a cylinder 97 secured to the shaft 75 by a spring 96 and a pin 98 is 
arranged within a cam ring 99. The spring 96 is wound around a boss 
portion of the sheet supply roller gear 88 and the cylinder 97, and one 
end of the spring 96 is connected to the cam ring 99 and the other end of 
the spring is connected to the cylinder 97. 
With this arrangement, during rotation of the shaft 75 due to the rotation 
of the sheet supply roller 88 in a direction shown by the arrow 92, when a 
free end of a lever 91 is caught by a projection 99a of the cam ring 99, 
the rotation of the cam ring 99 is stopped. Further, the support shaft 75 
connected to the cam ring 99 via the spring 96 and the cylinder 97 is also 
stopped. In this condition, since the end 96a of the spring 96 is also 
stopped, the winding force of the spring 96 with respect to the boss 
portion of the sheet supply roller gear 88 is loosened, with the result 
that only the sheet supply roller gear 88 continues to rotate. 
On the other hand, when the sheet supply roller gear 88 is rotated in the 
direction shown by the arrow 83 by a predetermined amount by the motor M2, 
the free end of the lever 91 is disengaged from the projection 99a, 
thereby tightening the spring 96, with the result that the sheet supply 
roller gear 88 is connected to the support shaft 75 to rotate in a 
direction shown by the arrow 92, thereby rotating the sheet supply 
rollers. Rollers 84 rotatably mounted on the shaft 79 are contacted with 
other pinch rollers 82 and are driven by the movement of the sheet K to 
direct the sheet K to the main roller 5. 
Next, a sheet convey operation of the sheet convey apparatus according to 
the fourth embodiment will be explained with reference to FIGS. 7 and 8. 
In response to a sheet supply command from a computer, the controller 84 
energizes the motor M1 to rotate the main roller 5 in the normal sheet 
convey direction shown by the arrow 29. At the same time, the controller 
84 also energizes the motor M2 to rotate the sheet supply roller gear 88 
in the direction shown by the arrow 93 by a predetermined amount. As a 
result, since the free end of the lever 91 is disengaged from the 
projection 99a, the spring 96 is tightened, with the result that the 
rotation of the sheet supply roller gear 88 is transmitted to the sheet 
supply rollers 76, thereby rotating the roller 76 in the direction shown 
by the arrow 92. When a largest diameter portion of each sheet supply 
roller 76 is contacted with the upper surface of the sheet stack K, the 
uppermost several sheets K are shifted toward the separating pawl, where 
only the one uppermost sheet is separated. The separated sheet is conveyed 
toward the main roller 5 by the sheet supply rollers 76 and the auxiliary 
roller 80. 
When the tip end of the sheet K is detected by the sensor S1, the 
controller 84 controls the rotational amount of the motor M1 to convey the 
tip end of the sheet by a length L shown in FIG. 8. Since the protruded 
amount N of the tip end of the sheet was previously explained in 
connection with the first embodiment, the explanation will be omitted 
here. 
Then, the controller 84 rotates the motor M1 reversely to rotate the main 
roller 5 in the direction shown by the arrow 31 by a predetermined amount, 
thereby shifting the sheet K in the reverse direction. At the same time, 
the controller 84 also rotates the motor M2 to rotate the auxiliary roller 
80 in the direction shown by the arrow 94, thereby applying a normal 
direction shifting force to the sheet K. 
The following is a description of two methods for applying a shifting force 
to the sheet K using the auxiliary roller 80. 
In a first method, the peripheral speed of the auxiliary roller 80 is set 
to a normal or usual peripheral speed. On the other hand, when the spring 
force of the spring plate 81 for urging the sheet K against the pinch 
roller 82 abutted against the auxiliary roller 80 is made as small as 
possible within a range satisfying the normal direction conveying force, 
the auxiliary roller 80 slips on the surface of the sheet K, thereby 
applying a normal direction shifting force to the sheet K. In this method, 
if a sheet having a hard surface is used, it is feared that the surface of 
the sheet will be rubbed by the above-mentioned slip, thereby damaging the 
sheet. In order to prevent damage to the sheet, the controller 84 controls 
the motor M2 to decrease the peripheral speed of the auxiliary roller 80. 
As a result, since a distance that the auxiliary roller 80 slips on the 
surface of the sheet is decreased, the rubbing force of the auxiliary 
roller is weakened, thereby preventing damage to the sheet. 
In a second method for applying a shifting force to the sheet K using the 
auxiliary roller 80, the motor M2 is controlled so that, during the 
rotation of the main roller in the direction shown by the arrow 31, while 
the sheet K is being shifted in the reverse direction, the auxiliary 
roller 80 is driven while applying a normal direction shifting force to 
the sheet to rotate in a direction opposite to the direction shown by the 
arrow 94. This method is effected by the controller 84 in such a manner 
that a current and/or a voltage supplied to the motor M2 is controlled to 
make the normal direction shifting force applied to the sheet K by the 
motor M2 via the auxiliary roller 80 smaller than the rotational force 
applied to the auxiliary roller 80 by the reversed sheet K. 
When the tip end of the sheet is passed through the contact position 
between the main roller 5 and the hold-down rollers 11 by rotation of the 
main roller 5 in the direction shown by the arrow 31, even if a time 
difference occurs between the left tip end and the right tip end of the 
sheet, since the auxiliary roller 80 applies the shifting force to the 
sheet K substantially at a central portion of the sheet, when the whole 
tip end of the sheet has passed through the contact position, the sheet K 
is rotated around a contact point between the sheet and the auxiliary 
roller 80. Further, since the tip end of the sheet is urged against the 
contact position between the main roller 5 and the hold-down rollers 11 by 
the shifting force, the sheet is maintained along the contact position. 
From the above condition, when the main roller 5 is rotated in the 
direction shown by the arrow 29 by a predetermined amount by the 
controller 84, the left and right tip ends of the sheet K are again passed 
through the contact position along the contact position by the normal 
direction shifting force of the auxiliary roller 80, and then the sheet is 
conveyed to the record position of the recording head 14 without skew-feed 
and with high accuracy. 
Then, in response to a record signal, the sheet K is fed in the normal 
direction by a predetermined amount by the main roller 5, and the carriage 
13 is reciprocally shifted in the widthwise direction of the sheet, 
thereby effecting one line recording by the recording head 14. By 
repeating these operations, one page recording is effected on the sheet. 
During the conveyance of the sheet K by the main roller 5, although the 
motor M2 is stopped, the auxiliary roller 80 can freely be rotated in the 
direction shown by the arrow 94 by the action of the one-way clutch 95, 
with the result that since the auxiliary roller 80 follows the normal 
direction movement of the sheet K due to the main roller 5, the auxiliary 
roller 80 does not affect the load applied to the main roller 5, thereby 
permitting the conveyance of the sheet with high accuracy by the main 
roller 5. 
Incidentally, in the above-mentioned embodiment, while the apparatus in 
which the shifting force is applied to the sheet by the auxiliary roller, 
the auxiliary roller 80 and its pinch roller 82 may be omitted and the 
sheet supply rollers 76 may have above-mentioned function same as that of 
the auxiliary roller 80. Also in this case, the same technical effect as 
the aforementioned embodiment can be achieved. 
As fully mentioned above, in the sheet convey apparatus according to the 
present invention, the auxiliary roller is arranged at an upstream side of 
the main roller, and, during the reverse movement of the sheet by a 
reverse rotation of the main roller, the auxiliary roller applies the 
normal direction shifting force to the tip end of the sheet, thereby 
aligning the tip end of the sheet with the generatrix of the main roller 
with high accuracy, and further, the sheet is conveyed to the 
predetermined record position with high accuracy by the normal rotation of 
the main roller while maintaining the above condition. When the functions 
and operations of the main roller and the auxiliary roller are applied to 
register rollers used in a printing apparatus such as a copying machine, 
the same technical effect can be achieved. 
FIGS. 11 and 12 show a fifth embodiment of the present invention applied to 
an ink jet printer, where FIG. 11 is a schematic perspective view showing 
certain mechanisms of the printer, and FIG. 12 is a sectional view of the 
printer. 
In FIG. 12, the printer comprises an outer cover 101 and a lid 102 
pivotally mounted around a shaft 102a, which lid 102 also serves as a 
sheet tray. A sheet is inserted from an insertion opening 101a formed in 
the cover 101 and is discharged from a discharge opening 101b. 
Within a plurality of side plates 103 in the cover 101, there are arranged 
a sheet stacking plate 104 pivotally mounted on a shaft 104a and biased 
upwardly by a spring 105 toward a sheet supply roller 106, the sheet 
supply roller 106 being secured to a shaft 107 and having a large diameter 
portion (which can be contacted with a sheet) and a small diameter portion 
(which does not contact the sheet), sheet hold-down rollers 108 rotatably 
mounted on the shaft 107 and each having a radius shorter than the larger 
diameter portion of the sheet supply roller 106 and longer than the small 
diameter portion, a separation plate 109 rotatably mounted on a shaft 109a 
and biased by a spring 110 to be urged against the large diameter portion 
of the sheet supply roller 106 and the hold-down rollers 108 via a 
separation pad 111 having a high friction surface, a main roller 113 
secured to a shaft 112 and adapted to convey a sheet (supplied by the 
sheet supply roller 106 and guided by an upper sheet guide 128a and a 
lower sheet guide 171) at a constant speed, first pinch rollers 116 
rotatably mounted on a shaft 114 and adapted to urge the sheet against the 
main roller by force of springs 115 via the shaft 114, a platen 118 
including an ink absorb material 117 therein, sheet discharge rollers 120 
secured to a shaft 119 and adapted to discharge a sheet, second pinch 
rollers 123 rotatably mounted on a shaft 121 and adapted to urge a sheet 
against the discharge rollers by force of springs 122 via the shaft 121, a 
carriage 126 shiftable along guide shafts 124, 125 in a widthwise 
direction of the sheet, and a recording head 127 mounted on the carriage 
and adapted to effect printing by discharging ink from discharge opening 
portion 127a in response to image information. 
The carriage 126 is driven by a motor 129 provided on a central side plate 
128 having the sheet guide 128a, a pulley 130 secured to an output shaft 
of the motor, and a belt 131 wound around the pulley 130 and having one 
end attached to the carriage 126. 
Further, within the cover 101, there are arranged an electric operation 
substrate 133 having a plurality of switch buttons 132 protruding from 
holes of the cover 101, and an electric control substrate 134 on which a 
computer and memories are provided and adapted to control the operation of 
the printer. 
In FIG. 11, a plurality of auxiliary sheet supply rollers 135 are secured 
to the shaft 107, each having a large diameter portion and a small 
diameter portion that cooperate with the sheet supply roller 106 along the 
whole width of the sheet, thereby supplying the sheet. A cam plate 136 
secured to the shaft 107 is always abutted against a protruded portion 
104c of a guide portion 104b provided on the sheet stacking plate 104 by 
the action of the spring 105, so that, when the cam plate 136 is rotated 
together with the sheet supply roller 106, the sheet stacking plate 104 is 
lifted and lowered. Since a pulley 137 provided at one end of the main 
roller shaft 112 and a pulley 138 provided at one end of the discharge 
roller shaft 119 are interconnected via belt 139, the rotation of a motor 
M is transmitted to the discharge rollers 120 via the shaft 112. 
A cap support 141 on which a cap 140 for covering the discharge opening 
portion 127a of the recording head 127 is arranged has a rotary shaft 
141a, and a push-down cam portion 14lb. Since the cap support 141 is 
biased around the shaft 141a toward an anti-clockwise direction by a 
spring 142, during the shifting movement of the carriage 126, when a 
projection 126a of the carriage 126 abuts against the push-down cam 141b, 
the cap support 141 is lowered in opposition to the force of the spring 
142, thereby lowering the cap 140. When the projection 126a passed by the 
push-down cam 141b, the cap 140 is lifted to closely contact the discharge 
opening portion 127a, thereby covering the portion 127a. 
A pump 143 has a piston shaft 143b on which a rack 143a is formed, a 
suction port 143c, and a discharge port 143d, and the suction port 143c is 
connected to the cap 140 via a tube 140a and the discharge port 143d is 
connected to the platen 118 via a tube 144, so that ink sucked from the 
cap 140 can be discharged to the ink absorbing material 117 in the platen 
118. 
A pump drive gear 145 is provided on the shaft 112 so that it can be moved 
along the shaft 112 and it can be rotated together with the shaft 112. 
Normally, the pump drive gear 145 is biased by a spring 146 so as not to 
engage the rack 143a. Solid matters are apt to be adhered to the discharge 
opening portion of the recording head 127 and therearound, thereby causing 
poor ink discharge. In such a case, in order to effect a poor discharge 
recovery operation, under the command from a controller 134, the carriage 
126 is shifted to contact the discharge opening portion 127a with the cap 
140. 
In response to the shifting movement of the carriage 126, since the 
projection 126a of the carriage 126 shifts the pump drive gear 145 to a 
position shown by the two-dot and chain line, the gear 145 is engaged by 
the rack 143a. In this condition, when the gear 145 is rotated 
alternatively in the normal and reverse directions repeatedly within a 
predetermined angle range by the motor M, the rack 143a repeats the 
reciprocal movements in a straight direction. Since a piston is moved 
together with the piston shaft 143b, the pump 143 sucks the ink and the 
solidified ink from the discharge opening portion 127a, and the sucked ink 
is discharged to the ink absorbing material 117 in the platen 118. 
In response to a signal from the controller 134, the motor M rotates the 
main roller 113 via an output gear 147, a two-stage gear 148 and a main 
roller gear 149 secured to the shaft 112, thereby conveying the sheet. On 
the other hand, the motor M rotates a shaft 151 via the output shaft 147, 
a two-stage gear 150 and a gear 152 secured to the shaft 151. A first 
carrier 155 rotatably supporting a first planetary gear 154 meshed with a 
sun gear 153 secured to the shaft 151 and a second carrier 157 rotatably 
supporting a second planetary gear 156 are rotatably supported on the 
shaft 151, and the carrier is urged against the side surface of the sun 
gear 153 by a spring 158 so that the carrier is driven by the rotation of 
the sun gear 153. When the shaft 151 is rotated in a direction shown by 
the arrow 159 by the rotation of the motor M for rotating the main roller 
113 to convey the sheet to the normal direction, the first planetary gear 
154 is driven by the sun gear 153, with the result that the first 
planetary gear 154 is rotated and revolved while meshing with an inner 
gear 160. When the first planetary gear is disengaged from the inner gear 
160, a pin 155a is abutted against a pin 161, thereby stopping the 
revolution of the planetary gear. 
When the shaft 151 is rotated in a direction shown by the arrow 162 by the 
rotation of the motor M for rotating the main roller 113 to convey the 
sheet in the reverse direction, the first planetary gear 154 is rotated 
and revolved in the direction shown by the arrow 162. When the first 
planetary gear is disengaged from the inner gear 160, the planetary gear 
is engaged by a gear 163. In this condition, when the motor M continues to 
rotate in the direction shown by the arrow 162, the sun gear 153 rotates a 
notched gear 164 secured to the shaft 107 and having a notched portion 
164a via the first planetary gear 154 and the gear 163, and the notched 
gear 164 transmits the rotation in the sheet supply direction to the sheet 
supply roller 106 via the shaft 107. When the notched gear 164 continues 
to rotate and the notched portion 164a reaches the gear 163, the gear 163 
is rotated idly not to transmit the rotation to the notched gear 164, 
thereby stopping the notched gear 164 and the sheet supply roller 106. 
By the rotation of the shaft 151 in the direction shown by the arrow 162, 
the second planetary gear 156 is revolved in the same direction until a 
pin 157a of the carrier 157 is abutted against a pin 165. After this 
condition, when the shaft 151 is rotated in the direction shown by the 
arrow 159, the second planetary gear 156 is revolved in the same direction 
to continue to be engaged by the notched gear 164, so that the sun gear 
153 transmits the rotation in the sheet supply direction to the sheet 
supply roller 106 via the second planetary gear 156 and the notched gear 
164. When the notched gear 164 continues to rotate and the notched portion 
164a reaches the second planetary gear 156, the second planetary gear 156 
is rotated idly not to transmit the rotation to the notched gear 164, 
thereby stopping the notched gear 164 and the sheet supply roller 106. 
Next, a modification of the transmission portion will be explained with 
reference to FIGS. 11 and 13. In FIG. 13, the same elements as those in 
FIG. 11 are designated by the same reference numerals. 
In FIG. 13, a gear 166 having the same configuration as the sun gear 153 of 
FIG. 11 is secured to the shaft 151 in an opposed relation to the sun gear 
153. The first planetary gear 154, revolved while engaging the gear 166 is 
rotatably supported by the carrier 155. Since the carrier 155 is urged 
against a side surface of the gear 166 by a spring 167, the carrier 155 is 
driven by the rotation of the gear 166 to rotate in the same direction as 
the gear 166. Further, a gear 168 having the same configuration as the 
gear 163 of FIG. 11 is secured to a shaft 169 in an opposed relation to 
the gear 163, so that, when the gear 168 is driven by the first planetary 
gear 154, the gear 163 is also rotated. Now, when the arrangement of FIG. 
11 is so designed that the speed reduction ratio from the motor M to the 
main roller shaft 112 is the same as the speed reduction ratio from the 
motor M to the shaft 151 and the pump drive gear 145 drives the pump 143 
by its normal and reverse rotations of 125.degree., in FIG. 13, in order 
not to rotate the sheet supply roller 106 by the rotation of the shaft 151 
in the direction shown by the arrow 162, a non-synchronous movement zone 
170 from a position where the pin 155a is contacted with the pin 161 to a 
position where the first planetary gear 154 is engaged by the gear 168 
must have an angle greater than 250.degree.. For example, the angle of the 
non-synchronous movement zone 170 is set to 280.degree. in consideration 
of the margin. Accordingly, in order to increase the revolution angle of 
the first planetary gear 154, in FIG. 13, two sun gears are provided to 
reverse the non-synchronous movement zone. On the other hand, regarding 
the rotation of the shaft 151 in the direction shown by the arrow 159, 
when the pump 143 is operated, since the second planetary gear 156 is 
always rotated idly by the presence of the notched portion 164a not to 
transmit the rotation to the notched gear 164, the sheet supply roller 106 
is not driven. 
In the arrangement of the transmission portion in FIG. 13, since the 
revolution angle of the first planetary gear 154 is increased, and 
requires a large space and an increase in the number of gears and shafts, 
it is difficult to make the apparatus small-sized. The arrangement of the 
transmission portion of FIG. 11 solves the above problem by using the 
inner gear. 
Now, the inner gear will be explained with reference to an example of the 
design of the inner gear 160. When the number of teeth of the sun gear 153 
is Z.sub.1 (=18), the module thereof is M.sub.1 (=0.6), the number of 
teeth of the first planetary gear 154 is Z.sub.2 (=10) and the module 
thereof is M.sub.2 (=0.6), in the specification of the inner gear 160, the 
number of teeth of the inner gear becomes Z.sub.3 (=38) and the module 
thereof becomes M.sub.3 (=0.6). On the other hand, when the first 
planetary gear 154 is rotated by 280.degree., the sun gear 143 advances by 
14 teeth. When the sun gear 153 advances by 14 teeth, the first planetary 
gear 154 is rotated, while engaging the inner gear 160 and is revolved by 
14 teeth of the inner gear 160. 
The 14 teeth of the inner gear 160 correspond to an angle of about 
133.degree.. Accordingly, in comparison with the example of FIG. 13, it is 
possible to reduce the revolution angle, with the result that it is 
possible to arrange a plurality of planetary gears around a single sun 
gear, thereby permitting the size reduction of the transmission portion. 
Further, since the revolution of the first planetary gear 154 is effected 
while engaging the planetary gear by the fixed inner gear 160, there is no 
slip and the like, thus achieving the positive operation. 
Other than the above-mentioned design, depending upon the combination of 
the number of teeth of the sun gear and the number of teeth of the 
planetary gear, it is possible to further reduce the revolution angle. 
Next, a sheet supply operation according to a fifth embodiment will be 
explained with reference to FIGS. 11, 12 and 14 to 18. FIGS. 14 to 18 are 
sectional views showing the main sheet supply members of FIG. 11. 
Incidentally, in FIGS. 14 to 18, the same elements as those of FIG. 11 are 
designated by the same reference numerals. 
In FIG. 14, the upper sheet guide 128a provided on the end of the 
intermediate side plate 128 along the whole width of the sheet and the 
lower sheet guide 171 arranged along the whole width of the sheet serve to 
guide the sheet P supplied by the sheet supply roller 106 to the nip 
between the main roller 113 and the main pinch rollers 116 without bending 
the sheet, and a distance between the upper guide 128a and the lower guide 
171 is gradually decreased as the guides approach the nip between the main 
roller 113 and the main pinch rollers 116. FIG. 14 shows a condition 
before the sheet supply operation is started. In this condition, the sheet 
stacking plate 104 is in a lowered position, the pin 155a is abutted 
against the pin 161, the second planetary gear 156 faces the notched 
portion 164a of the notched gear 164, the separation pad 111 is contacted 
with the hold-down rollers 108, and a plurality of sheets P are stacked on 
the sheet stacking plate 104. 
Then, in response to a command from the controller 134 shown in FIG. 12, 
when the shaft 151 is rotated in the direction shown by the arrow 162 by 
the motor M shown in FIG. 11, the first planetary gear 154 is rotated 
while engaging the inner gear 160, and is further revolved around the sun 
gear 153 to engage the gear 163, thereby establishing a condition shown in 
FIG. 15. In FIG. 15, the sheet supply roller 106 rotated in the sheet 
supply direction by the sun gear 153, first planetary gear 154, gear 163 
and notched gear 164 shifts several sheets on the sheet stack P on the 
elevated sheet stacking plate 104 into the gap between the hold-down 
rollers 108 and the separation plate 109. On the other hand, the second 
planetary gear 156 is also revolved in the direction shown by the arrow 
162 until the pin 157a abuts against the pin 165. By such revolution, the 
second planetary gear 156 is disengaged from the notched gear 164. 
FIG. 16 shows a condition in which the sheet supply roller 106 was further 
rotated in the sheet supply direction by the further rotation of the shaft 
151 in the direction shown by the arrow 162. In this condition, the sheets 
are separated one by one by the cooperation of sheet supply roller 106 and 
the separation pad 111, and the tip end of a separated sheet P is conveyed 
to the contact position (nip) between the main roller 113 and the main 
pinch rollers 116 which are rotated in a direction opposite to the sheet 
supply direction. Since the sheet conveyed up to the contact position 
cannot be further advanced, the sheet supply roller 106 is rotated while 
slipping on the sheet P without flexing the sheet. Such slip can be 
obtained by the proper pressure from the springs 105, 110. 
Then, when the notched portion 164a reaches the gear 163, the gear is 
rotated idly to disconnect the driving force of the motor M from the sheet 
supply roller 106, thereby stopping the sheet supply roller 106. In 
condition in which the sheet supply roller 106 is stopped, since if the 
sheet is flexed the sheet supply roller is rotated reversely by the flexed 
sheet not to stop the sheet supply roller completely, it is necessary to 
supply the sheet without being flexed. During the rotation of the notched 
gear 164, since the sheet stacking plate 104 is lowered, the sheet is not 
urged against the sheet supply roller due to the lifting movement of the 
sheet stacking plate 104, so that the next sheet is not drawn by the sheet 
supply roller 106. 
FIG. 17 shows a condition in which the shaft 151 was rotated in the 
direction shown by the arrow 159 in FIG. 12 by the rotation of the motor 
for rotating the main roller 113 in the normal sheet convey direction. In 
this condition, the second planetary gear 156 is revolved in the direction 
shown by the arrow 159 to engage the notched gear 164. By this engagement, 
the sheet supply roller 106 is rotated in the sheet supply direction by 
the sun gear 153, second planetary gear 156 and notched gear 164. The 
rotation of the sheet supply roller 106 causes the sheet P to pass through 
the contact position between the main roller 113 and the main pinch 
rollers 116. In this case, the main roller 113 is being rotated in the 
normal sheet convey direction. 
FIG. 18 shows a condition in which the sheet supply roller 106 was finally 
rotated by further rotation of the shaft 151 in the direction shown by the 
arrow 159. In this condition, when the notched portion 164a reaches the 
second planetary gear 156 by rotation of the notched gear 164, the second 
planetary gear 156 is disengaged from the notched gear 164 to idly rotate, 
thereby disconnecting the driving force of the motor M from the sheet 
supply roller 106. As a result, although the sheet supply roller 106 is 
stopped while separating from the surface of the sheet P, the main roller 
113 conveys the sheet P to the predetermined position. During the 
conveyance of the sheet, hold-down rollers 108 are rotated by the movement 
of the sheet. As the sun gear 153 continues to rotate in the direction 
shown by the arrow 159, the second planetary gear 156 is revolved while 
engaging the inner gear 160 until the pin 155a abuts against the pin 161. 
As a further movement, in FIG. 12, the sheet P is fed in the normal 
direction by the predetermined amount by the motor M in response to the 
print signal from the controller 134, and the carriage 126 is reciprocally 
shifted in the widthwise direction of the sheet, during which one line 
printing is effected by discharging ink from the discharge opening portion 
127a of the recording head 127. By repeating such operations, one page 
printing is completed. After the printing, the sheet P is discharged from 
the discharge opening 101b by the discharge rollers 120. 
As fully mentioned above, in the transmission portion according to this 
embodiment, the rotational amount in the direction shown by the arrow 162 
required by the motor M is the sum of the revolution amount of the first 
planetary gear 154 and the rotational amount of the notched portion 164a 
of the notched gear 164 up to the gear 163; whereas, the rotational amount 
in the direction shown by the arrow 159 required by the motor M is the sum 
of the revolution amount of the second planetary gear 156 and the 
rotational amount of the notched portion 164a of the notched gear 164 up 
to the second planetary gear 156 and the idle rotation amount of the 
second planetary gear 156. Thus, in both cases, by appropriately setting 
the idle rotation amount, the rotation position of the sheet supply roller 
106 is accurately controlled by the notched portion 164a without the 
accurate control of the motor M. 
Next, the operation of the sheet stacking plate 104 in the fifth embodiment 
will be explained with reference to FIGS. 11, 12 and 19 to 21. FIGS. 19 to 
21 are sectional views showing main members associated with the operation 
of the sheet stacking plate 104 in FIG. 11. 
In FIG. 19, a free end 104d of the sheet stacking plate 104 pivotally 
mounted on the shaft 104a is always biased upwardly by the spring 105. By 
this upward biasing force, rotation of the cam plate 136 is prevented in a 
condition in which the projection 104c of the guide portion 104b is 
received in a recess 136a of the cam plate 136 secured to the shaft 107. 
In the position where the projection 104c is received in the recess 136a, 
the cam plate 136 maintains the sheet stacking plate 104 in the lowered 
position. 
In FIG. 20, when the sheet supply roller 106 is rotated in the sheet supply 
direction, since the cam plate 136 is also rotated in synchronism with the 
sheet supply roller 106 via the shaft 107, the projection 104c moves out 
of the maximum lift profile 136b of the cam plate 136, with the result 
that the free end 104d of the sheet stacking plate 104 is lifted by the 
force of the spring 105 until it contacts the large diameter portion of 
the sheet supply roller 106. In this condition, the sheet stack resting on 
the sheet stacking plate 104 is urged against the large diameter portion 
of the sheet supply roller 106 so that a sheet can be fed out by the 
rotation of the sheet supply roller 106. 
In FIG. 21, when the cam plate 136 is further rotated in synchronism with 
the further rotation of the sheet supply roller 106 in the sheet supply 
direction, the projection 104c is pushed by the cam surface 136c of the 
cam plate 136 and then the projection continues to be pushed by the 
maximum lift profile 136b, and, at last, the condition shown in FIG. 19 is 
restored. In this condition, since the free end 104d is separated from the 
large diameter portion of the sheet supply roller 106, the sheet supply 
roller 106 does not shift the sheet in this position; on the other hand, 
the sheet urged against the sheet supply roller 106 by the spring 105 via 
the separation pad 111 is shifted by the rotation of the sheet supply 
roller 106. 
Next, another sheet stacking plate drive mechanism will be explained with 
reference to FIGS. 11, 12 and 22 to 24. In FIGS. 22 to 24, the same 
elements as those of FIG. 11 are designated by the same reference 
numerals. 
In FIG. 22, a cam plate 172 having a projection 172a and a gear 173 are 
secured to a common shaft 174, and the gear 173 is rotated by a gear 176 
secured to the shaft 107 via gear 175. Since the number of teeth of the 
gear 173 is the same as the number of teeth of the gear 176, when the 
sheet supply roller 106 is rotated by one revolution, the cam plate 172 is 
also rotated by one revolution. A recess 177b is provided in a side 
portion 177a of a sheet stacking plate 177 so that, when the sheet supply 
roller is in a position shown in FIG. 22, the projection 172a of the cam 
plate 172 is engaged by the recess 177b. 
In this condition, an end 177c of the sheet stacking plate 177 is lowered 
in the lowermost position. With this arrangement, since the engagement 
position between the cam plate 172 and the sheet stacking plate 177 can be 
selected or determined by selecting or determining the number of teeth of 
the gear 175 for driving the cam plate 172, the degrees of freedom in 
design can be increased. 
In FIG. 23, when the cam plate 172 is rotated in synchronism with the 
rotation of the sheet supply roller 106, the projection 172a moves out of 
an upper surface of the side portion 177a of the sheet stacking plate 177, 
with the result that the sheet stacking plate 177 is lifted by the spring 
105, thereby abutting the end 177c against the large diameter portion of 
the sheet supply roller 106. 
In FIG. 24, in synchronism with the further rotation of the sheet supply 
roller 106, when the cam plate 172 is also rotated, since the upper 
surface of the side portion 177a is pushed down by the maximum lift 
profile 172b of the cam plate 172, the sheet stacking plate 177 is 
lowered. By the further rotation of the sheet supply roller 106, the 
condition shown in FIG. 22 is restored. 
Next, a sixth embodiment of the present invention will be explained with 
reference to FIGS. 11, 12 and 25. FIG. 25 is a sectional view of a 
recording apparatus according to a sixth embodiment. In FIG. 25, the same 
elements as those of FIGS. 11 and 12 are designated by the same reference 
numerals. 
In the fifth embodiment, the sheets are separated one by one by the 
cooperation of the separation pad and the sheet supply roller. However, in 
this sixth embodiment, thin sheets are separated one by one by a corner 
separation pawl, and thick sheets such as post cards, envelopes and the 
like are separated one by one by a so-called abut separation method 
wherein the sheets are separated one by one by abutting the sheets against 
an inclined surface. 
In FIG. 25, a pawl member 180 having a pawl portion 180a is pivotally 
mounted, via a rotary shaft 179, on a side plate 178b provided at a side 
of a sheet stacking plate 178 rotatably supported by a shaft 178a. The 
pawl member 180 is always biased by a spring 181 toward the sheet stacking 
plate 178. A switch lever 183 rotatably mounted on a shaft 182 serves to 
switch the separation mode between the pawl separation mode and the abut 
separation mode. A free end 183a of the lever 183 is engaged by a hook 
portion 180b provided on the pawl member 180. When the lever 183 is 
rotated in a clockwise direction, a distance between the pawl portion 180a 
and the sheet stacking plate 178 is increased, so that the sheets can be 
inserted below the pawl portion 180a. The inserted sheets can be separated 
one by one by the pawl portion 180a. 
When the lever 183 is rotated in an anti-clockwise direction, since the 
pawl portion 180a is entered into a recessed portion 178c formed in the 
free end of the sheet stacking plate 178 by the action of the spring 181, 
the sheets can be stacked on the pawl portion 180a, and the sheets stacked 
on the pawl portion 180a can be separated one by one by abutting the 
sheets against an inclined surface 184a of an inclined surface member 184. 
The sheet supply roller 106 having a large diameter portion and a small 
diameter portion is secured to the shaft 107, and the sheet supply roller 
106 supplies a separated sheet toward the main roller 113 by two 
revolutions. The supplied sheet is pinched between the main roller 113 and 
the main pinch rollers 116, and is fed to a predetermined position. Since 
further operation is the same as that explained in connection with FIG. 
12, the explanation thereof will be omitted. 
Next, a transmission portion according to the sixth embodiment will be 
explained with reference to FIGS. 25 and 26. FIG. 26 is a schematic 
perspective view showing the transmission portion and therearound 
according to the sixth embodiment, and, in FIG. 26, the same elements as 
those of FIG. 11 are designated by the same reference numerals used in 
FIG. 11. 
In FIG. 26, when the shaft 151 is rotated in the direction shown by the 
arrow 159 by the motor M via the gears 150,152, the first planetary gear 
154 is revolved in the direction shown by the arrow 159 until the pin 155a 
abuts against the pin 161. On the other hand, the second planetary gear 
156 is revolved in the same direction to rotate the notched gear 164 
secured to a shaft 185 in the direction shown by the arrow 159 while 
engaging the notched gear 164. During this rotation, when the notched 
portion 164a reaches the second planetary gear 156, the second planetary 
gear 156 is rotated idly not to transmit the driving force to notched gear 
164. 
Then, when the shaft 151 is rotated in the direction shown by the arrow 162 
by the motor M, the first planetary gear 154 is rotated while engaging by 
the inner gear 160 and is further revolved in the direction shown by the 
arrow 162, and then rotates the notched gear 164 in the direction shown by 
the arrow 159 while engaging the gear 163. The rotation of the notched 
gear 164 is transmitted to the sheet supply roller 106 via a gear 186 
secured to a shaft 185, a gear 188 secured to a shaft 187 and a gear 189 
secured to the shaft 187. Since the number of teeth of the gear 186 is the 
same as the number of teeth of the gear 188 and the number of teeth of the 
gear 189 is twice the number of teeth of the gear 190, when the notched 
gear 164 is rotated by one revolution, the sheet supply roller 106 is 
rotated by two revolutions in the sheet supply direction. 
To the cam plate 172 secured to the shaft 174 and performing the same 
operation as explained in connection with FIGS. 22 to 24, the rotation of 
the notched gear 164 is transmitted via the gear 173 secured to the shaft 
174, gear 175 and gear 190. Since the number of teeth of the gear 173 is 
set to be twice the number of teeth of the gear 190, when the sheet supply 
roller 106 is rotated by two revolutions, the cam plate 172 is rotated by 
one revolution in the direction shown by the arrow 159 and returned to its 
original position. 
Next, a sheet supply operation according to the sixth embodiment will be 
explained with reference to FIGS. 25 and 26. 
In FIG. 25, when the switch lever 183 is rotated in the clockwise 
direction, since the pawl 180a is separated from the surface of the sheet 
stacking plate 177, a plurality of sheets are inserted into the space. On 
the other hand, if thick sheets are used, the lever 183 is rotated in the 
anti-clockwise direction. 
In FIG. 26, when the main roller 113 is rotated to convey a sheet reversely 
by rotation of the motor M in response to a signal from the controller 
134, the gear 152 is rotated in the direction shown by the arrow 162 via 
the gear 150. From the position where the pin 155a of the carrier 155 is 
abutted against the pin 161 secured to the side plate, the first planetary 
gear 154 is revolved in the direction shown by the arrow 162 through the 
non-synchronous movement zone having a predetermined angle to engage the 
gear 163. By the rotation of the gear 163, the notched gear 164 is also 
rotated in the direction shown by the arrow 159. The rotation of the 
notched gear 164 is transmitted to the sheet supply roller 106 via the 
gears 186, 188, 189, 190, thereby rotating the sheet supply roller 106 in 
the sheet supply direction. On the other hand, when the cam plate 172 is 
rotated in the direction shown by the arrow 159 via the gears 190, 175, 
173, the projection 172a is disengaged from the recess 177b of the 
stacking plate 177, thereby lifting the sheet stacking plate 177 to urge 
the upper surface of the sheet stack resting on the sheet stacking plate 
177 against the sheet supply roller 106. 
In this condition, when the uppermost sheet is shifted by the sheet supply 
roller 106, the tip end of the sheet rides over the pawl portion 180a in 
FIG. 15, and then, the tip end of the sheet is supplied to the contact 
position between the main roller 113 and the main pinch rollers 116 by the 
rotation of the sheet supply roller 106. During the plural revolutions of 
the sheet supply roller 106, when the notched portion 164a of the notched 
gear 164 reaches the gear 163, since the gear 163 is rotated idly, the 
transmission of the driving force is disconnected to stop the notched gear 
164, thereby stopping the sheet supply roller 106. 
Then, when the main roller 113 is rotated to feed the sheet normally by the 
motor M, the sun gear 153 is rotated in the direction shown by the arrow 
159, and, in synchronism with this rotation, the first planetary gear 154 
is revolved to disengage from the gear 163. On the other hand, in a 
condition that the pin 157a of the carrier 157 is abutted against the pin 
165, the second planetary gear 156 is revolved in the direction shown by 
the arrow 159 to engage the notched gear 164, thereby rotating the notched 
gear 164 in the direction shown by the arrow 159. By this rotation, since 
the sheet supply roller 106 is also rotated in the sheet supply direction 
to shift the sheet, the tip end of the sheet passes through the contact 
position between the main roller 113 and the main pinch rollers 116 which 
are being rotated in the normal direction, and then the sheet is conveyed 
to the predetermined position by the main roller 113. 
At the end of the plural revolutions of the sheet supply roller 106, the 
small diameter portion of the sheet supply roller 106 reaches the sheet 
surface to separate the sheet supply roller from the sheet, and at the 
same time, the maximum lift profile of the cam plate 172 pushes down the 
upper surface of the projection 177a of the sheet stacking plate 177, 
thereby releasing the action for urging the sheet against the sheet supply 
roller 106. 
When the notched portion 164a of the notched gear 164 rotated by the second 
planetary gear 156 reaches the second planetary gear 156, since the second 
planetary gear 156 is rotated idly to disconnect the transmission of the 
driving force, the notched gear 164 and the sheet supply roller 106 
connected to the notched gear 164 via the gear are stopped. At the stopped 
position, the projection 172a of the cam plate is engaged by the recess 
177b of the sheet stacking plate again. 
In the above-mentioned two embodiments, by using a reading head in place of 
the recording head, the sheet convey apparatus can easily be applied as an 
original reading apparatus. Further, by using the pair of main rollers of 
this apparatus as register rollers of a copying machine, the sheet convey 
apparatus can easily be applied to a copying machine. 
Incidentally, the recording head in the above embodiments is of the ink jet 
type. The ink jet recording head serves to record characters and the like 
on the sheet by forming ink droplets corresponding to the record signal by 
causing a change in condition (including the formation of bubbles) in the 
ink by utilizing thermal energy. 
As mentioned above, according to the present invention, it is possible to 
convey the sheet in a direction perpendicular to the generatrix of the 
main roller with high accuracy regardless of the thickness of the sheet 
(thin sheet, thick sheet or the like), by performing a series of sheet 
supply operations in which the transmission portion for transmitting the 
driving force of the output shaft of the motor for driving the main roller 
to the sheet supply roller having the large and small diameter portions is 
controlled by a predetermined amount of normal and reverse rotation of the 
motor, and, during one direction rotation of the motor, the transmission 
portion drives the sheet supply roller through the predetermined 
non-synchronous movement process to cause the sheet supply roller to 
supply a sheet to the pair of main rollers, and then the transmission 
portion stops the sheet supply roller, and then, during the other 
direction rotation of the motor, the transmission portion further drives 
the sheet supply roller to cause the sheet supply roller to pass the sheet 
through the nip between the pair of main rollers. 
Further, since the sheet supply roller can be arranged in the proximity of 
the main roller, it is possible to make the apparatus small-sized. In 
addition, since the non-synchronous movement process can be effected by 
the transmission portion without providing special members and a plurality 
of mechanisms can be driven by the single motor by providing the 
non-synchronous movement process, it is possible to provide a sheet convey 
apparatus which is inexpensive.