Typewriting machines – Sheet or web
Reexamination Certificate
1999-12-08
2001-11-06
Eickholt, Eugene (Department: 2854)
Typewriting machines
Sheet or web
C347S104000
Reexamination Certificate
active
06312177
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a line printer for simultaneously printing characters etc, while feeding print paper in units of lines.
2. Description of the Related Art
Heretofore, a line printer for simultaneously printing characters etc. according to a print signal input from a host, feeding print paper in units of line has been used.
FIG. 4
is a side view showing the outline of a print paper feeding mechanism in a general line printer.
As shown in
FIG. 4
, when a stepping motor
401
is rotated counterclockwise by a predetermined amount as shown by an arrow, the above-mentioned rotation is transmitted to a platen roller
404
via two gears
402
and
403
. As a result, the platen roller
404
is rotated clockwise and feeds print paper
405
in units of lines. In a synchronous matter therewith, the printer prints characters etc. in response to a print signal from a host (not shown) by driving a print head
406
, while feeding the print paper
405
in units of lines.
FIG. 5
is a timing chart showing a conventional driver signal in the case that the stepping motor
401
is driven. When printing according to a print signal is executed in an area A and is completed, a driver signal to the stepping motor
40
i is stopped in an area D and the stepping motor
401
is stopped. In the next operation, first, a driver signal of the same phase as a supplied phase when the stepping motor
401
is stopped, is supplied, to align the position (area E). Thereafter, the printing operation is started (area G) by supplying a driver signal of the next phase.
When a driver signal sent to the stepping motor
401
is stopped and the stepping motor is in a state in which it is not excited, a counterclockwise force is applied to the shaft of the platen roller
404
by the spring force of the platen roller
404
, because the print head
406
is fixed. As a result, a clockwise torque is applied to the stepping motor
401
via the gears
403
and
402
. When the above-mentioned torque exceeds inhibiting torque that the stepping motor
401
per se has, the stepping motor
401
is rotated clockwise.
Therefore, when the stepping motor
401
is next driven, a phase output from a motor control circuit and the actual phase of the stepping motor
401
are asynchronous. Therefore, when a driver signal of the same phase as a phase when the stepping motor
401
is stopped, is supplied to the stepping motor
401
(area E of
FIG. 5
) so as to drive the motor next, if the stepping motor
401
is reversed by more than two steps, the motor is reversed to the same phase before four steps or steps of a multiple of four from a position where the stepping motor
401
is stopped, and printing is started from the above-mentioned position (area G of FIG.
5
). Accordingly, there arises a problem in that printing for the four steps or the steps of the multiple of four is packed at the head.
To prevent the above-mentioned situation, a method of supplying holding current of low voltage to the stepping motor
401
while the stepping motor
401
is stopped is also conceivable. However, consumed current is increased and it is particularly a large problem in a line printer driven by a cell.
SUMMARY OF THE INVENTION
The present invention has been made to solve the abovementioned problems, and therefore an object of the invention is to provide a line printer in which large power consumption is not required and turbulence when printing is started, can be inhibited.
According to the present invention, there is provided a line printer for rotating a platen roller by forwardly rotating a motor by motor control means to feed a print paper by a fixed amount, and synchronously therewith, for effecting printing by driving a print head in accordance with a print signal, characterized in that:
the motor control means turns off the motor after reversing the motor by a predetermined amount when the motor is turned off to stop printing; and the motor control means starts printing operation after forwardly rotating the motor by the same predetermined amount to start printing. The motor control means turns off the motor after reversing the motor by the predetermined amount when the motor is turned off to stop printing, and starts a printing operation after forwardly rotating the motor by the above-mentioned predetermined amount to start printing.
The above-mentioned motor control means may be configured so that the motor control means turns off the motor after reversing the motor by a predetermined amount in case that a printing condition is not met within-a predetermined time after the printing of one line is completed.
Also, the above-mentioned motor may be composed of a stepping motor, and configured so that the motor control means turns off the stepping motor after reversing the stepping motor by a predetermined number of steps when the stepping motor is turned off to stop printing; and the motor control means starts printing operation after forwardly rotating the stepping motor by the predetermined number of steps to start printing.
Further, the above-mentioned motor control means may be configured so that the motor control means forwardly rotates the stepping motor by the predetermined number of steps after outputting the same phase as a phase output immediately before turning off the stepping motor, to the stepping motor when the stepping motor is driven to start printing, and then starts the printing operation.
REFERENCES:
patent: 4586834 (1986-05-01), Hachisuga et al.
patent: 4707159 (1987-11-01), Hirano et al.
patent: 5226741 (1993-07-01), Kumazaki et al.
patent: 5344244 (1994-09-01), Fukahori et al.
patent: 5502477 (1996-03-01), Osada et al.
patent: 5807000 (1998-09-01), Kawamura et al.
patent: 6132120 (2000-10-01), Yamaguchi et al.
Adams & Wilks
Eickholt Eugene
Seiko Instruments Inc.
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