Disk printer inking mechanism

A serial disk printer which includes an ink roll is disclosed. During printing, the print disk is continuously rotated at a constant speed as it moves across the print line. The motion of the carrier across the print line does not begin until rotation of the print disk has been brought up to speed. In order to avoid unnecessary delay, the rotation of the print disk is not immediately stopped at the end of each line of printing. Instead, after each line of printing the carrier is returned to a home position and the disk is rotated for several seconds so that in the event printing of another line is required shortly after the completion of a line of printing the disk is still rotating and there will not be any delay before printing can begin. Ink is applied to the print disk by an ink roll which is in contact with the print disk. A mechanism is provided to lift the ink roll from the print disk while the disk is idling in home position. Thus, there is no wear on the ink roll while it is in home position. In a second embodiment of the invention, an added element keeps the ink roll rotating when the carrier is in home position so that there is minimal relative motion between the ink roll and the print disk when they are brought into contact.

SUMMARY OF THE INVENTION 
Description of the Prior Art 
Serial printers with constantly rotating print disks are well known in the 
prior art. For example, such a printer is shown in U.S. Pat. No. 3,461,235 
(Willcox), issued Aug. 12, 1969. One such printer which is commercially 
available is the IBM 3612 Passbook and Document Printer. 
It is also known that ink can be efficiently provided to a print disk by 
use of an ink roll. The commercially available IBM 3612 Passbook and 
Document Printer includes such an ink roll. 
The prior art also shows printers where the ink roll can be moved to an 
inoperative position. For example, U.S. Pat. No. 3,526,309 (Marion) shows 
a printer where the ink roll is only operative periodically. This patent 
shows a serial printer wherein ink is supplied to the print wheel from a 
transfer roll which, in turn, receives ink from an ink roll. In the 
printer shown in this reference, the ink roll is not engaged and supplying 
ink while printing is taking place. Instead, the ink roll is engaged with 
the transfer roll when the carrier is returned to its home position; 
however, a groove in the transfer roll prevents ink from being applied to 
the print wheel in the home position. It should be specifically noted that 
with the apparatus shown in this reference, the ink roll is subject to 
wear while the printer idles in home position. Furthermore, the apparatus 
shown in this reference for applying ink is quite complex. 
Other references showing ink rolls include, for example, U.S. Pat. Nos. 
3,253,542 (McDonough), 3,296,962 (Gopperton), 3,826,191 Pittis, 3,785,288 
(Hunter), and 3,745,920 (McKay). Examples of references showing mechanical 
components similar to some of the components applicant uses include U.S. 
Pat. No. 3,080,038 (Spalla), IBM Technical Disclosure Bulletin, Vol. 17, 
No. 4, September 1974, page 1122, Vol. 18, No. 4, September 1975, page 
1118, and Vol. 16, No. 3, August 1973, page 951. However, taken alone or 
together, these references do not show or suggest the applicants' novel 
combination of elements. These references do not teach how to achieve an 
increased ink roll life and increased overall response time as does the 
applicants' invention. 
OBJECTS OF THE INVENTION 
An object of the present invention is to provide an improved inking 
mechanism for a constantly rotating disk printer. 
Another object of the present invention is to provide an improved printer 
wherein ink roll life is substantially improved. 
Still another object of the present invention is to provide an ink roll 
mechanism for a serial disk printer wherein no wear will take place on the 
ink roll while the print is idling at the beginning of a line. 
Yet another object of the present invention is to improve the overall 
response time of a constantly rotating disk printer without decreasing ink 
roll life. 
GENERAL DESCRIPTION OF INVENTION 
Replacement of an ink roll is a relatively simple operation. However, over 
a period of time the cost of ink rolls can be substantial and the 
inconvenience to the operator can be a negative factor in customer 
acceptability of the printer. It is thus highly desirable to minimize wear 
on ink rolls. Applicants' invention is directed toward minimizing ink roll 
wear and toward extending the life of the ink rolls. 
In serial printers with constantly rotating disks, such as those where this 
invention is applied, the disk must be brought up to speed prior to the 
time that the carrier begins traversing the print line. In order to 
minimize the amount of delay prior to the initiation of printing, when a 
line of printing is completed, the carrier is returned to a home position 
and rotation of the disk is maintained at normal speed for some period of 
time. In this way, if another line of printing is called for during the 
interval while the disk is still rotating, printing can begin immediately. 
Applicants recognized that a significant amount of needless wear of the 
ink roll takes place during the time when the carrier is in home position 
and the print wheel is rotating prior to the initiation of printing. 
Applicants' invention is directed toward the elimination of this needless 
wear on the print roll. Furthermore, since applicants eliminate the wear 
on the print roll while the print disk is idling in home position, they 
can maintain the disk rotating for a longer period of time in the home 
position, thereby increasing the probability that the disk will still be 
rotating when another line of printing is called for. 
Applicants eliminate wear on the ink roll when the printer is in home 
position by use of novel ink roll support bracket and an actuator which is 
attached to the frame of the machine. When the carrier is moved to the 
home position, the actuator interacts with the ink roll support bracket to 
automatically lift the ink roll from contact with the print disk. Thus, 
when the carrier is in home position the ink roll is disengaged and there 
is no wear on the ink roll while the printer idles in home position. 
Since there is no wear on the ink roll when the printer is idling in home 
position, the printer can be allowed to idle in home position for longer 
periods of time thereby increasing the probability that the disk will 
already be up to speed when another line of printing is called for. The 
net result is to shorten the response time of the overall system. 
In a second embodiment of the invention, a relatively large diameter 
friction disk is attached to the ink roll so that even when the ink roll 
is disengaged from the print disk the friction disk still makes contact 
with the print disk and the ink roll rotational velocity is maintained. In 
this way, when the ink roll is brought back into contact with the print 
disk, the ink roll and the print disk have substantially the same velocity 
and the frictional wear is minimized. The edge portion of the friction 
disk is slanted so that the thickness of the friction disk decreases as 
one moves further out on the edge of the disk. The slanted edge insures 
that the friction disk always engages the inside of the print wheel, 
hence, the ink roll tangential velocity always equals the velocity of the 
surface of the print disk which is being inked. 
The foregoing and other objects, features and advantages of the invention 
will be apparent from the following more particular description of 
preferred embodiments of the invention, as illustrated in the accompanying 
drawings.

DETAILED DESCRIPTION 
An overall view of the first embodiment of the present invention is shown 
in FIG. 1. This embodiment includes a frame 10 which is shown in schematic 
form, a platen 12, a carrier 13, a print disk 14 and a hammer mechanism 
16. The print disk 14 is driven from a motor 20 through a belt (not 
shown), a threaded drive shaft 22 and a beveled gear 24. A split nut (not 
shown in detail) is attached to beveled gear 24 in such a manner that the 
motion of drive shaft 22 not only rotates print disk 14, but also moves 
the carrier 13 across the platen 12. The details of the print disk drive 
mechanism and of the print hammer 16 are not shown or described in detail 
herein since the details of these parts do not constitute a part of the 
present invention and, furthermore, they are part of commercially 
available products, such as the IBM 3612 Passbook and Document Printer. 
The printer operates as follows. Print disk 14 is rotated at a relatively 
high velocity as the carrier 13 is moved across the print line. Actuation 
of hammer mechanism 16 is synchronized with the rotation of print disk 14 
so that a selected character is printed in a particular print position by 
actuating the hammer mechanism 16 at the appropriate time. 
A relatively large amount of energy is required to accelerate the print 
disk 14 from a stopped condition to print velocity and it thus requires a 
relatively long period of time to accelerate the print disk 14 from a 
stopped condition to print velocity. 
When one line of printing is finished, the carrier 13 is returned to a home 
position at the left margin and rotation of the print disk 14 is 
maintained at print velocity for several seconds. If printing of another 
line is called for during the interval where the disk is in home position 
rotating at print velocity, printing of this next line can begin almost 
immediately. After idling the print disk for several seconds in home 
position, if no further printing is called for, the motor 20 is stopped 
and the print disk coasts to a stop. Thereafter, when the next line of 
printing is called for, there is a several second delay before the print 
disk can be brought up to print velocity so that printing can begin. 
The present invention is directed toward the mechanisms for applying ink to 
the print disk 14. This mechanism is generally indicated by numeral 30 in 
FIG. 1. A first embodiment of this mechanism is shown in detail in FIG. 2. 
The inking mechanism includes an ink roll 31 which is mounted on a support 
bracket 32. Support bracket 32 includes a pivot 33 and a lever arm 34. 
Pressure on lever arm 34 will pivot the support 32 about pivot 33 and 
moves ink roll 31 away from contact with print disk 14. An actuator 35 is 
mounted on frame 10. When the carrier 13 is moved to the home position, 
actuator 35 is brought into contact with lever arm 34, thereby pivoting 
the support 32 about pivot 33 and removing the ink roll 31 from contact 
with disk 14. A cushion 36 reduces noise and the wear on the lever arm 34. 
Set screw 37 which pushes against frame 10 adjusts the position of 
actuator 35 so that the amount of lift off can be adjusted. 
Utilizing the present invention, the print wheel 14 can be allowed to idle 
in home position for a longer period of time since the ink roll is not 
engaged while the carrier is in home position. Since the print wheel can 
be kept at idle in home position for a longer period it increases the 
probability that the disk will already be up to speed when printing is 
called for and it eliminates the delay which would be required if one had 
to wait to bring the print wheel up to print speed. 
The present invention is particularly useful in applications, such as the 
IBM 3612 Passbook and Document Printer, which include a plurality of print 
disks. In such printers, under many circumstances one printer is utilized 
several times prior to the utilization of the second printer. Added costs 
would be involved in turning one printer off while it was not being 
utilized for printing. On the other hand, if the ink rolls were left in 
contact with the print disks during this idle time, there would be 
substantial needless wear on the ink roll. This needless wear on the ink 
roll is eliminated by the present invention. 
A second embodiment of the present invention is shown in FIGS. 3 and 4. The 
difference between the first and second embodiment is that the second 
embodiment has a friction disk 41 attached to the side of ink roll 31. As 
shown in FIG. 4, friction disk 41 engages the side of print disk 14. FIG. 
4 illustrates the relationship between the ink roll 31, friction disk 41 
and print disk 14 when the ink roll 31 in its disengaged position, that is 
when ink roll 31 has been "lifted off" print disk 41. It is noted that 
flange 41 continues to engage the edge of print disk 41 even though ink 
roll 31 is removed from print disk 14. The edge 41A of friction disk 41 is 
beveled so that the contact between friction disk 41 and print disk 14 is 
along the inside edge 14A of print disk 14. The reason for this is that if 
friction disk 41 were flat, it might engage edge 14B of print disk 14, 
thereby causing the print roll 31 to rotate at a higher velocity. 
The purpose of friction disk 41 is to maintain the rotational velocity of 
ink roll 31 even when the ink roll 31 is not in contact with the print 
disk 14. In this way, when the ink roll 31 is brought back into engagement 
with print disk 14, there is minimal amount of slippage and hence a 
minimum amount of wear on ink roll 31. A spring 55 represented by arrow 45 
in FIG. 4 biases the side of friction disk 41 against the edge of print 
disk 14. 
The details of the second embodiment are shown in FIG. 3. The mechanism 
includes a pivot 51, a bifurcated bracket 52, and an actuator arm 53. The 
actuator arm 53 is attached to the frame 10. The location of the actuator 
arm 53 relative to the frame 10 can be adjusted by means of a set screw 
54. The pivot 51, bracket 52, actuator arm 53 and set screw 54 are similar 
to the first embodiment. Ink roll 31 is fixedly attached to frictional 
disk 41. Both ink roll 31 and frictional disk 41 are slideably mounted on 
a shaft 56 which is attached to bifurcated frame 52. A spring 55 biases 
the combined ink roll 31 and friction disk 41 up against print disk 14. 
Spring 55 could be replaced by a coil spring. 
The edge 41A of friction disk 41 is beveled at about 3.degree.. It is noted 
that in FIGS. 3 and 4, the bevel is exaggerated for the purposes of 
illustration. It is noted that ink roll 31 could be a commercially 
available ink roll of relatively standard design. 
While the invention has been particularly shown and described with 
reference to preferred embodiments thereof, it will be understood by those 
skilled in the art that the foregoing and other changes in form and 
details may be made therein without departing from the spirit and scope of 
the invention.