Printer with a fixed and an axially movable character ring

A serial printer includes two character rings having raised characters disposed therearound. Both rings rotate on a common axis for selection of characters for printing. One character ring is laterally fixed relative to the common axis; the other character ring translates laterally along the common axis in a carriage driven by a pulley and wire, and biased for quick return. A solenoid actuated claw selects characters for printing as the character rings rotate. A single motor operating in a forward direction causes the character rings to rotate while character selections are made, sequentially causes a single hammer to strike both character rings simultaneously for printing on paper, and translates the carriage one position for serially printing the next digit in a number. Reversal of the motor, after a line of characters is printed, causes release and return of the carriage and advancement of the paper.

BACKGROUND OF THE INVENTION 
This invention relates generally to an electromechanical serial printer and 
more particularly to a serial printer for printing characters in a line by 
moving one of two character rings in a lateral direction. In the prior 
art, dot printers have been used wherein the characters are constituted of 
a plurality of tiny dots. However in many instances, the printed character 
became obscure and the structure of the dot head for producing the dots on 
the paper was complicated and expensive. In other printers the number of 
print rings was made equal to the number of columns or digits which were 
to be printed in a single lateral line. Such an apparatus was costly and 
complicated and generally required separate circuitry including a solenoid 
plunger associated with each individual print ring in order to set the 
characters for printing. 
What is needed is a serial printer providing the quality in printing 
normally achieved with pring rings but not having the complexity of a 
printer having an individual print ring associated with each digit in a 
serial number which is to be printed. 
SUMMARY OF THE INVENTION 
Generally speaking, in accordance with this invention, a serial printer is 
provided which includes only two character rings having raised characters 
disposed therearound. Both rings rotate about a common axis for selection 
of characters for printing. One character ring is laterally fixed relative 
to the common axis; the other character ring translates laterally along 
the common axis in a carriage drawn by a pulley and wire. As the character 
rings rotate, solenoid actuated claws select the characters on each ring 
for printing. Through a train of gears, a single motor causes the 
character rings to rotate until character selection is made, and through a 
system of cams and levers causes a single hammer to strike both print 
rings for printing on paper after the character selection has been made. 
Then continued operation of the motor translates the carriage holding the 
translatable character ring by one position or column for printing the 
next digit in a number. The steps of rotating the character rings, 
selecting characters and printing is repeated until an entire line of 
print is completed. Then, reversal of the motor after the line is printed, 
causes release and return of the carriage to the first digit standby 
position and advancement of the paper by a linkage mechanism. 
Accordingly it is an object of this invention to provide a serial printer 
which is simple and economical in construction. 
Another object of this invention is to provide a serial printer which is 
small-sized and light in weight. 
A further object of this invention is to provide a serial printer which 
provides clearly printed characters. 
Still another object of this invention is to provide a serial printer which 
uses a single motor operating in two directions and uses a single hammer 
for printing. 
Yet another object of this invention is to provide a serial printer which 
utilizes a laterally translatable print ring for printing the characters 
in a line of print. 
Still other objects and advantages of the invention will in part be obvious 
and will in part be apparent from the specification. 
The invention accordingly comprises the features of construction, 
combination of elements, and arrangement of parts which will be 
exemplified in the construction hereinafter set forth, and the scope of 
the invention will be indicated in the claims.

DESCRIPTION OF A PREFERRED EMBODIMENT 
With reference to FIGS. 1, 3 and 5, the printing action of the serial 
printer of this invention is first described. The printing cycle begins 
when the motor 13 receives an external signal to activate the motor. Motor 
13 rotates in the direction indicated in FIG. 1 by the arrow A. The drive 
wheel 1 is connected to the shaft 51 of the motor 13 and rotates therewith 
to drive the following wheel 2. In turn, the following wheel 2 drives the 
transmitting wheel 301 and transmitting wheel 302 connected thereto. The 
teeth of transmitting wheel 302 engage the first clutch wheel 4 which is 
frictionally connected to cam wheel 5. The cam 6 rotates with cam wheel 5 
in the direction indicated by the arrow F. As best seen in FIGS. 1 and 3, 
the cam 6 is provided with first and second cam grooves 601, 602. The pin 
161 arranged at the end of the hammer lever 16, is loosely set in the 
first groove 601, and a pin 81 secured at the end of the character reset 
lever 8 is loosely set in the second groove 602. 
The intermediate wheel 12 connects to the shaft 52, and is rotated by the 
intermediate wheel 7, and the cam wheel 5 in the direction indicated by 
the arrow E. Prior to the selection of characters for printing, the print 
character rings 181 and 182 rotate with the shaft 52 until a character 
selection is made. A timing detection plate 11 rotating with the 
intermediate wheel 12 is used in a mechanical wiper or electro-optical 
arrangement which provides a series of electrical signals (FIG. 6) 
indicative of the position of the shaft 52 and the print characters on the 
rings 181, 182. The position signals from detection plate 11 are fed into 
an external control unit (not illustrated) which outputs signals for the 
selction of a character on the print ring which is to be printed. When the 
character on the print ring which is desired for printing arrives in the 
position opposed to the hammer 17, the trigger coil 21 of a solenoid (FIG. 
5) is electrically actuated and the coil plunger 20 is caused to move 
leftward. The selecting claw 19, pivotally attached to the coil plunger 20 
by pin 53, pivots about the pin 54 and engages the ratchet wheel 39 which 
is attached to the side of the print ring 181. This prevents further 
rotation of the print ring until after printing has been accomplished. It 
should be understood that each print ring 181, 182 has an independent 
trigger coil 21 and trigger coil plunger 20 such that each print ring can 
be set for the selection of an individual character without regard to the 
selection made on the other ring. The motor 13 and the cam wheel 6 
continue to rotate after the character selection is completed. As the cam 
6 rotates, pin 161 attached to the hammer level 16 and engaging the first 
groove 601 of the cam 6, slides into the projecting portion 603 of groove 
601. By following the cam, the hammer lever 16 and the hammer 17 coupled 
to the hammer lever 16 are moved in the direction indicated by the arrow 
D. Accordingly the hammer 17 strikes the desired character which is 
opposed on the character print rings 181, 182 through the medium of the 
intervening recording paper 36. The hammer 17 extends substantially the 
entire width of the printer between the opposite side frames 37, 38. Thus, 
regardless of the position of the translatable print ring 182, the 
characters which have been selected on both rings 181, 182 are printed 
simultaneously by the action of the hammer 17. As seen in FIG. 7, two 
characters, that is, characters in each of two laterally spaced columns, 
i.e. columns 1 and 2, are printed at the same time. In the first action of 
the print hammer 17 in a print cycle, the two print wheels, 181, 182 will 
be located so as to print the two righthanded columns on the paper (FIG. 
7). If the printed line is to contain more than two characters spaced 
laterally apart, then additional characters are added to the same line by 
movement of the print ring 182 to the left by one column at a time, 
allowing the printing of an additional character at each column position 
until the entire line, e.g. a number, is completed in serial form. The 
print ring 181 at the most right-handed position remains laterally fixed 
at all times. 
After each printing action of the hammer 17, the solenoid 20 is deenergized 
causing the selecting claw 19 to release the ratchet wheel 39, allowing 
the character print rings 181, 182 which are spring biased to return to a 
standby condition ready for the next character selection. 
The action for laterally translating the character print ring 182 is now 
described. After a printing action of hammer 17 is completed, the cam 6 
continues to rotate in the direction indicated by the arrow F. The 
continued tracking of pin 161 around continuous cam 601 causes the hammer 
17 to return to its original position, disengaged from the paper and the 
print ring. After a printing motion of the hammer 17 is completed, the cam 
6, pin 81, and the first character reset bar 8, are in the positions shown 
in FIG. 3. As the motor 13 and cam 6 continue to rotate, the pin 81 slides 
into the recess portion 604 of the second cam 602. The first character 
reset lever 8 is driven in the direction indicated by the arrow C in FIGS. 
1 and 3. The second character reset lever 25, which is provided on the 
opposite frame 38, is also driven through the action of the character 
reset bar 10. This movement of character reset lever 25 is transmitted to 
the carrier arm 28, carrying lever 31, and carrying pawl 34 (FIGS. 2 and 
4). Thus the cam shape 604 causes the pawl 34 to extend to the right (FIG. 
4) and engage the next tooth on the ratchet wheel 40. Continued rotation 
of the motor 13 and cam 6 causes pawl 34 to withdraw to the left and 
rotate ratchet wheel 40 by one tooth. The pulley 33, rigidly attached to 
and rotating with the ratched wheel 40, is rotated and winds up the wire 
35 attached to the carriage 60 which supports the print character ring 182 
along with its associated solenoid coil 21 and plunger 20. The action of 
the pawl 34 in rotating the pulley 33 opposes a spring (not shown) which 
biases the pulley 33 to return in the direction indicated by the arrow J 
in FIG. 2. However the ratchet lock pawl 32 prevents back rotation of the 
ratchet 40 and pulley 33 until the time of release as described more fully 
hereinafter. Advancement of the ratchet 40 by one tooth translates the 
carriage 60 by a pitch distance P as shown in FIG. 7 and displaces the 
character print ring 182 in position for printing, for example, the next 
most significant digit in a laterally spaced serial number. 
At each position of the character print ring 182, a printing operation is 
performed as described above. The hammer 17, because of its extended 
length strikes characters on both character print rings simultaneously at 
all lateral positions of print ring 182. However, after character print 
ring 181 has printed its first character, for example, a "+" sign as shown 
in FIG. 7, the external character selector control unit (not shown) will 
then select a blank space on character print ring 181 for all subsequent 
printing positions of character print ring 182 during the serial printing 
of an entire laterally spaced number. Thus if the first action of the 
hammer 17 in printing a serial number causes the character print ring 181 
to print, for example, a "+" sign, then until the entire number is 
completely printed, the fixed character print ring 181 will print nothing 
more. Printing of one entire line is completed by repeating the 
above-mentioned character selection, printing, and translation of the 
character print ring for the required number of times, N, as indicated in 
FIG. 7. Characters can be omitted at any column by selecting a blank space 
on the character ring in opposition to the hammer 17. 
After a line has been finished, (FIG. 2), it is necessary to advance the 
paper and to return the character ring 182 to its original position (FIG. 
1) adjacent the laterally fixed character ring 181. This is done by 
reversing the rotational direction of the motor 13 as indicated by the 
arrow B in FIG. 1. It should be noted that when the motor 13 is reversed, 
the intermediate wheel 12 connected to the character wheels 181, 182, and 
cam wheel 5 connected to cam 6, are prevented from reverse rotation by the 
pawl 9 which engages the teeth on cam wheel 5. The reversed motion of the 
motor 13 is transmitted via drive wheel 1, following wheel 2, transmitting 
wheel 301 and transverse shaft 41 to the clutch wheel 26 shown in FIG. 2. 
During the printing process, described previously, the second clutch wheel 
26 is at a standstill even though the transmitting wheel 3 is rotating in 
the direction indicated by arrow H in FIG. 2. That is, when the shaft 41 
is turning in the direction indicated by the arrow H, as it would during 
the printing operations, the pin 42 provided through the shaft 41 slides 
on the side surface of the clutch wheel 26 in order to prevent the second 
clutch wheel 26 from rotating. When the motor 13 is operating in reverse 
and the shaft 41 is rotating in the direction indicated by the arrow G, 
then the clutch wheel 26 rotates to drive the paper feed wheel 24. Also as 
the paper feed wheel 24 is rotated, the cam 240, which is connected to or 
in one body with the transmitting wheel 24, rotates in unison. A 
projecting portion 241 of the cam 240 pushes upwardly on one end 291 of 
the column reset lever 29 as indicated by the arrow I in FIG. 2 and FIG. 
4. The column reset lever 29 pivots about shaft 58 causing the attached 
pin 293 to press downwardly on the ratchet pawl 32 thereby releasing the 
pawl 32 from the ratchet wheel 40. Simultaneously, the pin 292 connected 
to the column reset lever 29 presses downwardly on the carrying pawl 34 
releasing it from the ratchet wheel 40. Accordingly the ratchet 40 is free 
from restraint and the aforementioned spring (not shown), which biases the 
ratchet wheel 40 and carrying pulley 33, causes the carriage 60 bearing 
the print character ring 182 to return to its original standby position 
adjacent to the laterally fixed print character ring 181. As the paper 
feed wheel 24 and carriage release cam 240 continue to turn, the elevated 
portion 241 disengages from the column reset lever 29. Pulled by the 
tension spring 56 acting on the end 291 of the column reset lever 29, the 
lever 29 pivots about shaft 58 allowing the ratchet pawl 32 to fall into 
engagement again with ratchet wheel 40. The carrying pawl 34, biased by a 
spring (not shown) swings back into engagement with a tooth of the ratchet 
wheel 40 and thus the serial printer of this invention is ready for the 
next print cycle. The rotational motion of the ratchet wheel 40 and the 
pulley 33 in returning the carriage 60 to its standby position is 
indicated in FIG. 2 by the arrow J. The paper transmitting wheel 24 
continues to rotate until the tooth 242 on the cam 240 engages with a 
tooth of the paper feeding wheel 27 whereby the paper feeding roller 14 is 
rotated by the pitch distance l as shown in FIG. 7. The paper feeding 
roller 14 is on a shaft coaxial with the paper feeding wheel 27. An ink 
roller 22 is associated with each character print ring 181, 182. As the 
print rings 181, 182 are rotated, the raised surfaces of the characters 
are wetted with ink which is then available for impression on the paper 
36. 
FIG. 6 is a timing chart showing the cycle to print an entire line on the 
paper 36. In the example illustrated in FIGS. 6 and 7, the number 784 is 
printed with a `plus` sign to the right. The number is printed starting 
with the least significant digit and progressing toward the most 
significant digit. The `plus` sign is printed from the character ring 181 
whose raised characters are not numbers but rather are symbols such as 
plus, minus, a division sign, and so forth as desired by the designers of 
the calculator or device in which the printer is used. The timing pulses 
in the upper line of FIG. 6 are those derived through use of the detector 
plate 11 connected to the shaft 52 which drives the print character rings 
181, 182. It should be noted in the given example that there are timing 
pulses for the characters 9 down to 0, followed by four empty spaces 
indicated by the mark sp. Then the cycle repeats. Whereas the character 
print ring 181 had symbols for its characters, the character print ring 
182 has the numbers from 9 down to 0; each ring has four empty spaces. On 
the second line of FIG. 6, it is illustrated that the laterally fixed 
character ring 181 is triggered by the solenoid 21 to select a `plus`. 
Just prior to that time, the character ring 182 is triggered by its 
solenoid to select a 4. With reference to the fourth waveform of FIG. 6, 
it is shown that the hammer 17 strikes after the characters have been 
selected and after the eleventh timing pulse. The carriage is then 
translated laterally shortly after the hammer 17 strikes (line 5, FIG. 6) 
by a distance P shown in FIG. 7, that is, from column 1 leftward to column 
2. It should be noted that thereafter, in subsequent timing cycles, 
character ring 182 prints an 8 and a 7, whereas the character ring 181 
prints nothing since it is positioned by the solenoid 21 so that an empty 
space sp is located opposite to the hammer 17. The lower waveforms (lines 
6, 7 of FIG. 6) show that the carriage is reset and then the paper 36 is 
advanced following the final printing of a character in the column N, and 
following reversal of the motor 13 (line 8 of FIG. 6). It will be readily 
understood, where the number to be printed does not require N lateral 
positions, that the external control (not shown) which determines the 
reversal time for the motor may deliver an early reversal signal to 
promptly begin a new line and speed up the printing process. 
It will thus be seen that the objects set forth above, among those made 
apparent from the preceding description, are efficiently attained and, 
since certain changes may be made in the above construction without 
departing from the spirit and scope of the invention, it is intended that 
all matter contained in the above description or shown in the accompanying 
drawings shall be interpreted as illustrative and not in a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention herein described 
and all statements of the scope of the invention which, as a matter of 
language, might be said to fall therebetween.