Printing – Selective or progressive – Bed and platen machines
Reexamination Certificate
1999-05-25
2001-04-10
Hilten, John S. (Department: 2854)
Printing
Selective or progressive
Bed and platen machines
C400S076000, C400S070000, C400S061000
Reexamination Certificate
active
06213013
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a skipping (draft) printer driving method, and in particular, to a skipping printer driving method for a line dot printer which is provided with dot printing elements (pins) which are arranged in the shape of a saw blade in a direction perpendicular to the paper feed direction.
DESCRIPTION OF THE PRIOR ART
FIG. 1
is a perspective view showing an example of a line dot impact printer, and
FIG. 2
is a schematic diagram showing an example of an arrangement of printing pins of the line dot impact printer of FIG.
1
. Referring to
FIG. 1
, paper
104
is placed between a platen
103
and an ink ribbon
102
. A hammer bank
101
which is placed parallel to the platen
103
swings in a direction parallel to the platen
103
(in a direction perpendicular to the paper feed direction). In other words, the hammer bank
101
moves a little to the direction of the arrow P which is shown in FIG.
1
and moves back a little to the direction of the arrow Q.
Referring to
FIG. 2
, the hammer bank
101
is provided with a plurality of hammer springs
105
, and each hammer spring
105
is provided with a printing pin
106
on its tip. The printing pins
106
are arranged in the shape of a saw blade. In other words, from left to right in
FIG. 2
, the length of the hammer springs
105
gradually increases by a predetermined length, returns to the first length, and thereafter repeats the variation. Such arrangement of the printing pins
106
is employed for increasing printing speed and printing dot density, and decreasing printing time and the heating value of the hammer bank
101
. The printing pins
106
provided on the tips of the hammer springs
105
of the hammer bank
101
hits the ink ribbon
102
on the paper
104
on the platen
103
, and thereby dot impact printing is executed.
In the following, conventional printer driving methods for driving printing pins (printing hammers) of line dot impact printers of a conventional type will be described referring to FIG.
3
through FIG.
10
.
FIG. 3
is a schematic diagram showing part of a conventional line dot impact printer in which a conventional printer driving method is employed. Referring to
FIG. 3
, the conventional line dot impact printer is provided with a head bank
1
which is placed in a direction A-A′ parallel to a platen (in a direction A-A′ perpendicular to the paper feed direction). The head bank
1
is provided with a plurality of printing hammers Di (printing elements Di) which are arranged at predetermined intervals C in the direction A-A′. The head bank
1
is supported and guided in the direction A-A′ by rails
3
a
and
3
b
, and is moved by an off centered disk
2
in the direction A-A′. The printing hammers Di are selectively driven at their predetermined dot positions respectively while the head bank
1
is shuttled back and forth in the direction A-A′ by the decentered disk
2
.
FIG. 4
is a schematic diagram showing the movement of the printing hammers Di (i=1~4, for brevity) on the shuttled head bank
1
. Incidentally, while the printing hammers D
2
and D
4
are drawn in
FIG. 4
lower than the printing hammers D
1
and D
3
for the sake of explanation and clear drawing, the printing hammers D
1
~D
4
are placed in line as have been shown in FIG.
3
. In
FIG. 4
, “E
1
”~“E
4
” indicate printing areas of the printing hammers D
1
~D
4
respectively, and each printing area includes 6 dot positions in this example. Each printing hammer D
1
~D
4
makes back-and-forth movements in the direction A-A′ as the head bank
1
moves, and the paper is moved by 1 dot in the paper feed direction when the head bank
1
reached the ends (the right-hand end and the left hand end) of the shuttle action. Therefore, the printing hammers D
1
~D
4
move on the paper along the lines shown in
FIG. 4
, during which each printing hammer D
1
~D
4
prints dots on the paper at the predetermined dot positions (aij, bij, cij or dij) which are arranged at predetermined intervals P. Broken circles in
FIG.4
are showing a moment at which the printing hammers D
1
~D
4
are at the dot positions a
32
, b
32
, c
32
and d
32
respectively.
FIG. 5
is a circuit diagram showing a driving circuit for driving the printing hammers D
1
~D
4
of the conventional line dot impact printer of FIG.
3
and FIG.
4
. The driving circuit of
FIG. 5
includes solenoids
4
~
7
, pairs of switching transistors (
16
,
17
), (
18
,
19
), (
20
,
21
) and (
22
,
23
), diodes
24
~
31
, transistors
9
and
10
, terminals
8
,
11
,
12
,
13
and
14
, etc. The solenoids
4
~
7
are provided in order to drive each of the printing hammers D
1
~D
4
. Excitation of the solenoids
4
~
7
is controlled by a print driving pulse F and print instruction signals (print control pulses) G
1
~G
4
which are shown in
FIG. 5. A
position detection signal is outputted by a rotary encoder etc. by detecting the movement of the head bank
1
, and the print driving pulse F is generated based on the position detection signal. The print driving pulse F is supplied to the terminal
8
when the printing hammers D
1
~D
4
reached dot positions (printing positions), thereby, the transistor
9
is turned on and the transistor
10
is turned on, and thereby the solenoids
4
~
7
are supplied with print driving voltages V. The print control pulses G
1
~G
4
are generated substantially in synchronization with the print driving pulse F, and the print control pulses G
1
~G
4
, having levels “1” or “0” according to a dot pattern outputted by a character generator, are supplied to the terminals
11
~
14
, and thereby the solenoids
4
~
7
are excited selectively.
FIG. 6
is a timing chart showing an example of timing of the print control pulses (print instruction signals) G
1
~G
4
. Dotted lines shown in
FIG. 6
indicate the print instruction signals of the level “0” so as not to print dots on the paper (i.e. so as not to excite corresponding solenoids
4
~
7
). Incidentally, in
FIG. 5
, the switching transistors (
16
,
17
) (
18
,
19
) (
20
,
21
), and (
22
,
23
) are connected in Darlington connection for obtaining a large current amplification factor. The diodes
24
~
27
are provided in order to protect the switching transistors (
16
,
17
), (
18
,
19
), (
20
,
21
) and (
22
,
23
), respectively. The diodes
28
-
31
is provided in order to form a closed circuit with the solenoid
4
and pass a loop current when the print control pulse G
1
-G
4
fall to “0”, (see Japanese Patent Application Laid-Open No.SHO61-35970, for example).
In the above printer driving method shown in
FIGS. 4 and 6
, all the printing hammers D
1
~D
4
are driven at the same instant when solidly shaded (black) patterns are printed on the paper, therefore, large momentary power consumption occurs in the driving circuit, and thus power consumption efficiency of the driving circuit is necessitated to be low. Further the noise level of the line dot impact printer is necessitated to be considerably high.
FIG. 7
is a schematic diagram showing another example of the movement of printing hammers Hi (i=1~4, for brevity) on the head bank
1
of the conventional line dot impact printer of FIG.
3
. The printer driving method shown in
FIG. 7
has been disclosed in Japanese Patent Application Laid-Open No. SHO61-35970. Also in this example, the printing hammers H
1
~H
4
are placed in line as in
FIG. 3
, although the printing hammers H
2
and H
4
are drawn in
FIG. 7
lower than the printing hammers H
1
and H
3
for the sake of explanation and clear drawing. Similarly to the case of
FIG. 4
, symbols “E
1
”~“E
4
” in
FIG. 7
indicate printing areas of the printing hammers H
1
~H
4
respectively, and each printing area includes 6 dot positions. Each printing hammer H
1
~H
4
makes back-and-forth movements in the direction A-A′ as the head bank
1
moves, and the paper is moved by 1 dot in the paper feed direction on the ends (the right-hand end and the left-hand end) of the shuttle action of the
Foley & Lardner
Hilten John S.
NEC Corporation
Nolan, Jr. Charles H.
LandOfFree
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