Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Reexamination Certificate
1998-07-20
2001-09-04
Yockey, David F. (Department: 2861)
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
C347S131000, C347S237000, C347S240000, C358S296000
Reexamination Certificate
active
06285384
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a non-impact printer and more particularly to a printer improved in printing quality to provide natural printing for a curve, a slash or the like.
2. Description of the Prior Art
Hitherto, in a non-impact printer such as an electrophotographic printer, an electrically charged photoconductor drum is illuminated with a light source to form an electrostatic latent image on a surface thereof, and developing is performed upon adhesion of a toner to the electrostatic latent image to form a toner image. Then, the thus obtained toner image is transferred to a recording material to be fixed thereon.
FIG. 2
is a block diagram of a printer control circuit in a conventional non-impact printer. In
FIG. 2
, a printing control unit
1
transmits, at the time a sheet arrives at a printing ready point, a timing signal
12
, including a line and a raster timing signal, to a host or another controller, and receives a video signal
11
which has been edited on each page in the other controller. The video signal
11
received by the printing control unit
1
is transmitted to an LED (Light Emitting Diode) head
19
in the form of a real printing data signal
18
.
FIG. 4
is a block diagram of the LED head in the conventional non-impact printer. In
FIG. 4
, the LED head
19
comprises a shift register
19
a
for storing in order a line of real printing data signal
18
from the printing control unit
1
shown in
FIG. 2
in synchronism with a clock signal
18
a
, a latch
19
b
for temporarily holding a line of real printing data signal
18
stored in the shift register
19
a
in accordance with a latch signal
17
, an LED group
19
c
wherein LED elements, the number of which corresponds to that of a line of dots, are arranged, and a driver group
19
d
for supplying the real printing data signal
18
held in the latch
19
b
to the LED group
19
c.
The shift register
19
a
in the LED head
19
stores in order the real printing data signal
18
in synchronism with the clock signal
18
a
. Upon receipt of a line of video signal
11
, the printing control unit
1
transmits a latch signal
17
to the LED head
19
. The latch
19
b
holds a line of real printing data signal
18
stored in the shift register
19
a
in accordance with the latch signal
17
. Before receiving the subsequent video signal
11
by the printing control unit
1
, the thus held real printing data signal
18
is transmitted to the LED group
19
c
in accordance with a printing drive signal
13
, so that the corresponding LED elements are lightened.
Transmission and receipt operation of the video signal
11
is performed in the unit of print lines.
FIG. 3
is an operational time chart of the conventional non-impact printer mentioned above. However, according to the conventional non-impact printer mentioned above, the same size of dots are printed on a sheet depending on the resolution of the LED head
19
which is determined by the arrangement of the LED elements at regular intervals in a raster direction. Thus, there will be retained a serrated edge-like image on a slash portion of the printed image due to the resolution.
FIGS. 5A
,
5
B and
5
C, and
FIGS. 6A
,
6
B and
6
C are views showing printing states according to the conventional non-impact printer.
FIGS. 5A and 6A
show 300 dots per inch (DPI) data;
FIGS. 5B and 6B
each show the relation between the print timing and driving energy for the LED head; and
FIGS. 5C and 6C
each show a real printing image.
As shown in the figures, both of the real printing images have undesirable serrated edge-like images, since the printing is performed on the predetermined raster lines. In view of the foregoing, if one contemplates increasing the density of the dots in order to improve the printing quality, then it is necessary to use an LED head
19
in which the LED elements are arranged at closer intervals or pitches. However, such an LED head
19
encounters a lower yield in manufacture of the parts where the LED elements are arranged, and thus becomes very expensive.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention, in view of the foregoing problems, to provide an improved printer.
It is another object of the present invention to provide a non-impact printer capable of receiving a video signal from another controller or a host controller, even if the video signal has a resolution higher than the print resolution of the printing unit, which will be defined by the arrangement pitch of the LED elements in a raster direction in the LED head.
It is still another object of the present invention to provide a non-impact printer capable of reducing a serrated edge-like image on a slash portion of the printed image by means of providing in appearance a higher dot density than the arrangement pitch or interval of the LED elements, thereby improving the printing quality.
It is still another object of the present invention to provide a non-impact printer which is inexpensive to manufacture.
In accordance with a preferred embodiment of the present invention, there is disclosed a non-impact printer provided with an LED head for printing and control means for providing a sequence control for the printer in its entirety in response to a control signal and a video signal from another controller, said control means including a print data receiving circuit adapted to receive the video signal from the other controller and transmit a timing signal to the other controller, said print data receiving circuit comprising: means for generating line timing signals defining printing on basic raster lines; means for generating additional line timing signals each defining printing on an additional raster line during an interval of a receiving timing of the line timing signals; first conversion means for converting partially bit data of the received video signal into a first signal representative of a data sequence corresponding to a resolution of the LED head; means for transmitting the first signal to the LED head in the form of a real printing data signal to be printed on the basic raster line in synchronism with the line timing signal; second conversion means for converting the remaining bit data of the received video signal, which are not converted into the first signal, into a second signal representative of another data sequence; a line buffer for storing the second signal transmitted from said second conversion means; and means for transmitting the second signal stored in said line buffer to the LED head in the form of a real printing data signal to be printed on the additional raster line in synchronism with the additional line timing signal, wherein said control means further includes means for setting a first LED head drive energy with which the basic raster lines are printed and a second LED head drive energy with which the additional raster lines are printed independently of each other.
In accordance with another preferred embodiment of the present invention, there is disclosed a non-impact printer provided with an LED head for printing and control means for providing a sequence control for the printer in its entirety in response to a control signal and a video signal from another controller, said control means including a print data receiving circuit adapted to receive the video signal from the other controller and transmit a timing signal to the other controller, said print data receiving circuit comprising: means for generating line timing signals defining printing on basic raster lines; means for generating additional line timing signals each defining printing on an additional raster line during an interval of a receiving timing of the line timing signals; a line buffer for storing the received video signal; first conversion means for reading out the video signal stored in said line buffer, converting bit data of the read out video signal into a first signal representative of a data sequence corresponding to a resolution of the LED head, so that a resolution in a raster dire
Ito Katsuyuki
Ito Toshikazu
Katakura Shinichi
Nagaoka Kazuhiko
Tanuma Jiro
Frank Robert J.
OKI Electric Industry Co., Ltd.
Venable
Wood Allen
Yockey David F.
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