Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SHEET FEEDER FOR TYPEW~ITERS
Summary of the Invention and State of the Prior Art
The present in~ention relates to sheet ~aper feed apparatus
for a typewriter, and more particularly relates to sheet
paper feed apparatus including means for removing the
bottom most sheet of paper and feeding the same to the
platen of the typewriter.
Shingling apparatus for separating sheets and feeding the
same have been in existance for sometime. For example, see
U. S. patent 3,008,709 issued on November 14, 1961 to
Booslik. The uses of such shingling apparatus has been
varied but conventionally has been employed in conjunction
with some normal force to remove either the topmost or
bottom most s~eet from a stack of sheets of paper. Typical
bottom sheet shingling apparatus is illustrated in IBM
Technical Disclosure Bulletin, Vol. 21, No. 9, February
1979, pages 3538, 3539; and 3540-3542; and U. S. patent
4,165,870, issued on August 28, 1979 to ~ohn L. Fallon, et
al.
In feeding indi~idual sheets of paper to the platen of a
typewriter, it is particularly advantageous if the sheet
feedex can distinguish a single sheet of paper and pre-
sent that single sheet of paper without additional drive
or feed rolls for insuring separation to the platen of the
typewriter inasmuch as th~s complicates the apparatus.
Moreover, inasmuch as once the paper is in position in the
platen for the typing operation, it is unnecessary to
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continue the feeding operation and, of course, it is
advantageous to permit of an automatic means of
discontinuing the shingling operation until it is again
necessary to provide a fresh sheet of paper to the platen
of the typewriter.
In view of the above, it is a prlnciple object of the
present invention to effect, in an easily attachable
attachment, a single sheet feed apparatus from a stack of
paper to the platen of a typewriter.
Another object of the present invention is to effect a
single sheet feed apparatus which may ~e easily and
economically constructed but which will operate reliably
and ~ith minimum operator attendance.
Yet another object of the present invention is to provide
a sheet feeder apparatus for a typewriter which may also
receive the fini~hed typed product.
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1 In its broad, general aspects there is provided a sheet
paper feed apparatus for a printing apparatus having a
platen for holding and providing at least longitudinal
motion to a sheet of paper, the apparatus comprising in
combination a rectangular tray including a rear paper
support portion and a spaced apart forward paper support
portion, at least one shingler wheel for engaging the
lower most sheet of the paper sheet stack, and drive means
connected to the shingler wheel; sensing means for indicat-
ing separation of the lowermost sheet and means responsive
to the sensing means indicating separation.
Other objects and a more complete understanding of the
invention may be had with reference to the following speci-
fication and claims taken in conjunction with the accompany-
ing drawings in which:
Drawing Description
Fig. 1 is a fragmentary perspective view of a typewriter
incorporating a sheet paper feeder constructed in accordance
with the present invention;
Fig. 2 is a fragmentary side elevational view of the sheet
feeder illustrated in Fig. l;
Fig. 3 is a plan view of the sheet feeder illustrated in
Figs. 1 and 2;
Fig. 4 is a fragmentary sectional view taken along lines
4-4 of Fig. 3;
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Fig. 5A-D is a series of schematic views illustrating the
feed of paper to and from the platen of a typewriter;
Fig. 6 is a schematic view of an electric drive circuit
for a sheet feeder constructed in accordance with the
present invention;
Figs. 7a and 7b are schematic diagrams of the sensor
circuitry which may be utilized in conjunction with the
apparatus of the present invention; and
Fig. 8, shown on the same page as Fig. 6, is a schematic
diagram of typical circuitry which may be employed for con-
trolling the operation of the apparatus illustrated and
associated with the sheet feeder of the present invention.
Referring now to the drawings, and especially Fig. 1 there-
of, a typical single element typewriter 10 having a sheet
feeder 20 attached thereto and constructed in accordance
with the present invention is illustrated therein. As
shown, the typewriter 10 includes a keyboard and the like
11, a platen 12 and a typing element 13 which moves
longitudinally of the platen 12 by means of a carrier (not
shown~ to imprint through, for example ribbon, indicia on
paper wound in a conventional manner around the platen 12.
In the present instance, the typewrlter 10 includes a
stepping motor and the like 14 which is coupled to the
pla~en 12 to efrect indexing of the platen (and thus a
sheet or sheets of paper~ either under operation of the
operator as through a keybutton 1~, automatically through
pre-programming or thxough the conventional carrier return
key located on the typewriter.
In accordance with the invention, the sheet feeder 20 is
adapted to receive a st~ack or bundle of sheets of paper,
remove the bottom sheet from the bundle and present the
same to the platen 12 of the typewriter, and receive the
finished sheet, if desired, from the platen. This is
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accomplished by ~irst shingling the st~ck or bundle so
that the bottom most sheet moves in a first direction
away from the typewriter platen, and upon sensing of the
single sheet the direction of movement of the shingler
wheel is reversed to place the individual sheet between
the ni~ of drive rolls which may conveniently be coupled
to the platen. Thereafter the paper is fed to the
platen so that as the platen rotates, the paper sheet is
removed from the sheet feeder. To this end, and referring
now to Figs. 1-4, the sheet feeder comprises a generally
rectangular tray 21 having upstanding sidewalls 22 and 23
which are spaced apart a sufficient distance to receive
a bundle or stack of paper 30 upon which characters or
other indicia may be imprinted by the typewriter 10. The
tray includes a rear paper bundle or stack support portion
24, and a spaced apart ~orward paper support portion 25,
the rear paper support portion 24 comprising a ledge or
shelf while the ~orward paper suppor~ portion preferably
comprises a pair of laterally spaced apart projecting
fingers 26 and 27. As best illustrated in Figs. 2-4, the
forward and rear paper support portions 25 and 24
respectively are spaced apart so as to provide an opening
28 therebetween for receiving at least one shingler wheel
29 which projects upwardly into the space 28 above the
plane formed by connecting the rear support portion 24 and
the forward support portion 25 so Ihat a stack of paper
30, supported by the rear support portion 24 and forward
support portion 25, will rest intermediate its ends upon
the shingler wheel 29 holding the paper stack or bundle 30
in a slightly bowed configuration (see Fig. 41. Thus the
shingler wheel 29 enga~es the bottom most sheet 30a of the
paper sheet stack 30.
.
In ordex to impart xotation to the shingler wheel 29 to
remove the bottom most sheet 30a from the bundle or stack
~ 35 30, drive means 31, for example a DC motor is coupled
- through a belt 32 to a pulley 33 mounted on a shaft 34
upon which is mounted the shingler wheeI 29. In a manner
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which will be more fully described hereinafter, upon
depression of a pack or paper feed button 16 on the
typewriter keyboard 11, (Fig. 1) the DC motor drive means
31 will effect rotation of the shingler wheel 29 in the
direction to effect shingling of the lower sheet 30a of
the stack or bundle 30 in a first direction which is up-
wardly or away from the platen 12 of the typewriter.
(Hereafter, up refers to the direction of sheet movement
away from the platen and down refers to the direction of
sheet movement towards the platen.) Shingling continues
until the lower most sheet 30a is driven so that its
lower edge 30b (Fig. 5a) drops off the forward support
portion 25 or off the fingers 26 and 27 (Fig. 3). This
condition is sensed by an upper or top sensor 35 which
causes a reversal of the direction of motion of the DC
motor 31 and thus a reversal in the direction of the motion
of the shingler wheel 29.
After sensing o~ the bottom most sheet 30a of paper, by
the sensor 35, and reversal of the motor drive 31 of the
shingler wheel 29, the bottom most sheet 30a having
dropped below the forward support portion 25 or fingers
26 and 27 is fed into and between a driven roller 40 and
an idler roller 40a which is mounted beneath each of
the fingers 26 and 27. In this connection, it should be
noted that the portion 25 includes a downwardly deflecting
camming surface 25a beneath the fingers 26 and 27 to aid
in sheet separation and guidance of the sheet, the camming
surface also mounting the idler roller 40a (Fi~. 4).
Adjacent the driven roller 40 is second sensor means or a
lower sensor 36 (see Fig. 4) which serves to shut off the
drive motor 31 stopplng the shingling action.
In order to drive the roller 40 to effect feeding of the
sheet of paper 30a through a slot like opening 50 to the
platen 12 of the typewriter, in the preferred embodiment,
the roller 40 which underlies both of the fingers 26 and 27
is connected to a shaft 41 which extends transversely of
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the tray 21 terminating in a gear 42 (Fig. 2~ which is
coupled through a driven gear 43 to a second driven gear
44, the purpose of the second driven gear 44 being more
fully explained hereinafter. In the preferred embodiment,
a belt 43a drive may be employed to connect the driven
gear 43 to the typewriter platen, or any other convenient
drive which would allow either manual rotation of the
platen to effect removal of the paper, or motorized move-
ment of the platen as by the motor 14 associated with the
typewriter to move the paper through the platen to a
start of print position. It should be recognized, however,
that the coupling of the roller 40 to effect rotation
thereof may be by any convenient mode or means to the
platen 12, or to another drive source, it only being
necessary that the lowermost sheet 30a of paper is fed
through the chute like slot 50 into the platen. Alter-
nately, the driven gear 42 may be coupled to the gear 45
on the platen shaft 12a so that rotation of the platen
effects rotation of the drive gear 42 and thus the gears
43 and 44.
In order to remove paper from the platen, and in accordance
with a feature of the present invention, the second driven
gear 44 is coupled as by a shaft 45a (see Fig. 2) which
also extends laterally of the tray 21, the shaft 45a being
connected to a pair of spaced apart driven rollers 46
which serves to press the paper against idler rollers 47
to effect removal of the paper from the platen and place
the finished sheet of paper on top of the stack 30.
It should be recognized that the operation of the tray pack
may be controlled by simple timing devices which permit a
time-out of the amount of time taken to move a bottom sheet
during the operation of the shingler upwards or away from
the platen and then a simple motor reversal with a sufficient
time to permit movement of that bottom sheet beneath the
ledge or fingers 26 and 27. Moreover, a simple electro-
mechanical sensor such as a microswitch with a latching
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circuit may be employed to control t~e direction of
rotation of the drive motor and its on and off period.
However, the double sensor arrangement described more
fully below is inexpensive and easily implemented and
therefore is to be preferred.
The drive circuit for the DC motor or drive means 31 for
the shingler wheel 29 is best illustrated in Fig. 6. As
shown, the drive is a standard H configuration 60
including a pair of PNP transistors 61 and 62 connected
to a voltage source Vl through resistor~ Rl and R2. The
lower half of the H of the drive 60 is formed by two NPN
transistors 63 and 64 having their emitters connected
to ground as at 65 and their collectors connected to the
collectors of the PNP transistors 61 and 62. ~he DC
motor 31 îs connected, as shown in Fig. 6, between the
collector to collector leads 66a and 66b respectively
connecting transistor 61 to transistor 63 and transistor
62 to transistor 64. The inputs to transistor 61 and 64
have been labeled "up" and for transistors 62 and 63 "down".
(This refers to the direction of motor rotation which
causes the bottom most sheet 30a of the stack 30 to move
"up" towards sensor 35 and "down" towards the platen.) As
illustrated, transistors 61 and 62 have a base input through
' biasing resistors R3 and R5 and resistors R4 and R6 connected
as shown to the output of invertors 67 and 68 respectively.
Moreover, the inputs to transistors 63 and 64 is through
a pair of invertors to each base, notably invertors 69,
70 and 71, 72~ Pull up resistors R7 and R8 as well as
R9 and R10 serve their conventional purposes. By way of
explanation, assume that an "up" signal (which refers
with respect to Fig. 8 to the direction that the lower
most sheet 30a is being driven by the shingler wheel 29,
in other words with respect to Fig. 4, the rotation of the
shingler wheel is in the countercloc~wise direction), and
that the "up" signal is a positive going wave form, the
invertor 67 inverts the wave form and turns on transistor
61 causing current to flow from the power supply tnrough
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transistor 61. ~dditionally, the "up" signal is also
applied to transistor 64 through the double inventor 71
and 72 turning on transistor 64. In this manner, current
flows through transistor 61, the motor 31 to the
transistor 64 and ultimately to ground 65. At the same
time, the signal on transistors 62 and 63 is low, these
transistors are turned off and no current flows through
transistors 62 and 63. In the manner just described,
the DC motor 31 will effect rotation of the shingler wheel
forcing the lower most sheet 30a upwardly until the sensor
35 "sees" the paper, and a reversal of the motor direction
and thus of the shingler wheel occurs. In this condition,
a positive wave form signal is applied tc the down inputs
of transistors 62 and 63 respectively, and the up signal
going to transistors 61 and 64 is turned off. The high
signal applied to the input of invertor 68 associated
with transistor 62 causes the PNP transistor 62 to turn
on permitting current to flow through transistor 62, the
motor 31 and the turned on transistor 63. Transistor 63
is turned on because of the positive going wave form
applied to invertor 69 and 70 effects a raising of the
base voltage of the NPN transistor 63 allowing current
to flow to ground 65 through that path and thus through
the DC motor causing a reversal of direction of the motor.
The control circuit for effecting turn on of the DC motor
31 and operation of the H drive 60 to cause motor turn on
and turn off as by the sensors 35 and 36 respectively is
described best in Fig. 7 and Fig. 8. Referring first to
Fig. ~, the sheet feed button 16, when depressed, causes
current to flow from the pull up resistor Rll through
the uncharged capacitor C1 to ground causing a negative
going spike to be formed at the input to a latch 80
causing an up going or positive wave form to occur at the
output labeled "up" which is applied to transistors 61
and 64 as heretofore described (Fig. 6). The "~OR" signa1
input to latch 80 occurs during machine turn on so that
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a power-on-reset signal causes the output "up" to be
initially low, i.e. "POR" sets the initial state of latch
80.
Referring now to Fig. 7a, the top or upper sensor 35
includes a standard source of voltage V2 which applies
the voltage through resistor Rll and R12 to light emitting
diode Dl and phototransistor 75. The phototransistor 75
is positioned on the same side of the sheet 30a as light
emitting diode Dl so that it operates in a reflectance
mode. The output of the phototransisto~ 75 is applied
to an amplifier 76 turning on NPN transistor 76 and
applying a pulse to a schmitt trigger invertor 77 and
through a second schmitt trigger invertor 78 to provide
a "sensor 35" output with a pulse shape similar to
that shown in Fig. 7a at the output of schmitt trigger
invertor 78. Upon the occurrence of the phototransistor
75 seeing a sheet of paper such as the lower most sheet
30a, sensor 1 provides an output such as illustrated in
Fig. 7a to the latch 80 causing latch 80 to change state
thus turning off transistors 61 and 64 and thus turning
off motor 3I.
Simultaneously the output sensor 35 is applied to a second
latch 81 which causes the output of that latch to go up,
the wave shape or form being substantially as illustrated
in Fig. 8 now turning on transistors 62 and 63 as
heretofore described and causing the DC motor 31 to operate
in the reverse direction. It should be noted that the
capacitor C2 gives a slight delay in the change of state
of latch 81 which insures that transistors 61 and 64 are
turned off prior to transistors 62 and 63 being turned on
to reverse motor direction.
'.
The bottom sensor 36 is identical to the top sensor 35 and
includes resistors R13, R14 connected to the source of
voltage V2, the sensor including a light emitting diode D2
and phototransistor 83 which operates, in the reflectance
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mode so that the NPN transistor amplifier 84 is turned
on when the phototransistor sees the presence of paper.
Once again, the output of the amplifier is through a pair
of schmitt trigger invertors 85 and 86 which outputs a
signal labeled "sensor 36", with a waveform substantially
as illustrated in Fig. 7b to the other device of the
latch 81 (Fig. 8), causing latch 81 to change state to
low, turning off transistors 62 and 63 respectively.
For ease of construction of the circuits shown in Figs.
6-8, a table of parts is set forth below.:
Table of Parts:
(All resistors 1/2 W. unless otherwise stated)
Rl, R2 - 5Q lW
R3, R5 - 2OK
15 R4, R6 - 5 K
R7, R10, Rlla,b, R17, R18, Rl9, R20 - lOK
R8, R9, R12, R14 - lK
R15, R16 - lOK Potentiometer
Cl, C2 - .Ol~fd
20 C3, C5 - .68~fd
C4, C6 - .OOl~fd
Transistors 61-64 Darlington Pairs
, ~
Although it is a simple matter for the typist to place the
stack of paper on the forward and rear paper support
portions 25 and 24 respectively, to prevent inadvertant
errors by the typist in failing to place the paper bundle
on the forward support or fingers 26 and 27, a temporary
support 90 having cutouts 91 and 92 in the area of the
fingers 26 and 27 is hingably connected to the upstanding
sidewalls 22 and 23 to support the bottom edge of the
paper stack when it is initially placed into the tray on
the rear paper support portion.
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As shown best in Figs. 2 and 3, the support 90 is operated
by a cover 95 which must be lifted by the operator about
pivot 96 when the operator loads paper into the tray onto
of the rear support portion 24 and the support 90. As the
cover member 95 is elevated about the pivot 96, linkage
97 coupled to the cover 95 effects clockwise rotation
(relative to FIG. 2) of a pair of cams 98 and 99 which
bear against the lower surface of the support 90, causing
the support 90 to rotate upwardly above the fingers 26
and 27 which form the forward support portion 25. In this
manner, when the operator inserts paper.onto the tray, the
cover is first elevated causing upward rotation of the
support 90 permitting paper to be placed thereon with no
chance of paper inadvertently separating and falling
beneath the fingers 26 and 27. As shown, as the cover is
rotated clockwise and placed on top of the stack or bundle
of paper, the cams 98 and 99 depress allowing the cover
member 90 to recess below the plane of the fingers 26 and
27 and permitting the stack of paper to be supported on
the fingers. The cover 95 also serves additional functions
of acting as a separator for finished sheets permitting easy
; separation by the operator, and as a weight for increasing
the pressure of the stack of paper against the shingler
wheel 29.
In order to accommodate different paper lengths, it is
preferrable that the sensor 35, as illustrated in FIG. 1,
be mounted on a slide 100 on the rear support portion 24
of the tray, the~slide 35 being fittable into a groove 101
and detented as at 102, 103 so that the operator may
choose the position of the first sensor 35 dependent upon
paper length. Of course, it should be recognized that with
suitable modifications the tray could be permitted to move
laterally to accommodate papers of varying widths.
As best illustrated in FIG. 1, the sheet feeder is preferrab`ly
~35 set at an angle with respect to the typewriter 10 which
facilitates the feed of paper to the platen 12. Thus the
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chute 50 will be preset at a particular angle for a
particular typewriter, and may be easily fastened or
connected to the rear cover or frame of the typewriter as
by the angled stand 104 in a conventional manner, such
as self-tapping screws, wing nuts and bolts, etc., or may
be made a permanent part of the typewriter as desired.
Moreover, if desired and as best shown in Fig. 3, a metallic
wire support grid llO having a suitable opening 28a therein
to permit the projection therethrough Gf the shingler wheel,
is provided with a convex bow. The grid is preferably
supported in the tray to insure bowing ~f the paper stack
30 in the desired direction, and by connecting the grid
110 to ground also serves to bleed off electrostatic
charges on the lower most sheet 30a of the paper stack 30.
Thus the sheet feeder of the present invention provides a
simple and economical pack feed capability for a typewriter,
especially being adapted to an automatic typewriter which
will permit of self-feeding of sheets of paper in a
position for a typist.
Although the invention has been described with a certain
degree of particularity, it is understood that the present
disclosure has been made only by way of example and that
numerous changes in the details of construction and the
combination and arrangement of parts may be made without
departing from the spirit and scope of the invention as
hereinafter claimed.
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