Printing device with print density changing function

Details Printing device with print density changing function Printing device with print density changing function

1998-04-13

2001-12-04

Barlow, John (Department: 2853)

Incremental printing of symbolic information

Ink jet

Controller

C347S010000, C347S011000, C347S014000, C358S001900, C358S502000

Reexamination Certificate

active

06325478

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printing device for printing desired images through controlling a print head.
2. Description of the Related Art
An ink-jet printing device has been proposed to print desired images through controlling an ink-jet print head.
SUMMARY OF THE INVENTION
It is conceivable to provide an ink-jet printing device which can perform both a printing function and a facsimile function.
The conceivable ink-jet printing device has an ink-jet print head for selectively ejecting ink droplets of four colors: cyan, magenta, yellow, and black onto print papers. When print data received from a host computer is for designating full color printing, the print head performs full color printing to selectively eject ink of the four colors. When facsimile data is received through a communication circuit, on the other hand, the print head performs monochromatic printing to eject ink of black color only.
The print head is designed to eject ink droplets through nozzles onto a print paper and to create ink dots on the print paper. The size of each dot, produced on the print paper, is determined dependent on the amount of ink included in each ink droplet ejected from one nozzle.
FIG. 1A
shows an ink dot
100
created on the printing paper through the monochromatic printing operation. That is, the print head ejects a single droplet of black ink from one nozzle according to one dot's worth of print data (one set of print data). The ink droplet permeates through the printing paper, spreads on the paper surface, and creates the ink dot
100
shown in FIG.
1
A.
FIG. 1B
shows another ink dot
200
created on the printing paper through the full color printing operation. During the full color printing operation, when color represented by a single dot's worth of print data is other than the four colors: black, cyan, yellow, and magenta, the print head uses two different colors to reproduce that color. That is, in order to reproduce the subject color, the print head ejects two droplets of different colors from different nozzles onto the same location on the paper. The two ink droplets permeate through the printing paper, spread on the paper surface, and create the two droplet-combined dot
200
shown in FIG.
1
B. It is noted that when color represented by the single dot's worth of print data is either black, cyan, yellow, or magenta, the print head uses only a single ink droplet in the same manner as during the monochromatic printing operatoin. Accordingly, the single droplet-forming dot
100
of
FIG. 1A
is created to reproduce that color.
Thus, during the monochromatic printing operation, each dot
100
is created from a single ink droplet having one dot's worth of ink amount. Accordingly, each dot
100
is made from ink with one dot's worth of amount. A monochromatic image will be produced as made from a plurality of dots
100
. During the full color printing operation, on the other hand, dots
100
and dots
200
will be created to print a full-color image. Each dot
100
is created from a single ink droplet, and therefore is made from ink with one dot's worth of amount. Each dot
200
is created from two ink droplets of different colors, each having one dot's worth of ink amount. The dot
200
is therefore made from ink with two dots' worth of amount. The dot
200
has a larger size than the dot
100
.
In order to perform both the monochromatic printing operation and the full color printing operation, the one dot's worth of ink amount is preferably selected to such a value that a full-color solid image
210
will be produced only from the two droplet-combined dots
200
shown in
FIG. 2
while forming no spaces among the respective dots
200
. The print head is therefore designed so as to be capable of ejecting, from each nozzle, a single ink droplet comprised of ink with the thus set one dot's worth of ink amount.
The thus designed print head prints a monochromatic solid image
110
also shown in FIG.
2
through the monochromatic printing operation. The monochromatic solid image
110
is made from a plurality of single droplet-forming dots
100
of FIG.
1
A. Because the dots
100
are smaller in size than the dots
200
, spaces
102
are formed among the respective dots
100
. Accordingly, the monochromatic solid image
110
presents print density lower than that presented by the full-color solid image
210
.
In view of the above, it is an object of the present invention to provide a printing device which can print monochromatic images, through monochromatic printing operation, at desirable print density.
In order to attain the above and other objects, the present invention provides a printing device capable of printing desired print information onto print medium, the device comprising: input means for receiving print information desired to be printed; print means for printing the received print information on a print medium; and density control means for controlling the print means to print the received print information at a print density while selectively controlling the print density into either a first print density or a second print density different from the first print density.
The printing device may further comprise judging means for judging whether the received print information is of a first type or of a second type different from the first type, the density control means controlling the print means to perform printing operation while controlling the print density, the density control means controlling the print means to print the received print information at the first print density when the received print information is judged to be of the first type, the density control means controlling the print means to print the received print information at the second print density when the received print information is judged to be of the second type, the second print density being different from the first print density.
According to another aspect, the present invention provides a printing device capable of printing desired print information onto print medium both in a single color and in a plurality of colors, the device comprising: input means for receiving print information desired to be printed; judging means for judging whether the received print information is of a first type print information which includes image information to be printed with a plurality of colors and image information to be printed with a single predetermined color or of a second type print information to be printed with the single predetermined color; print density adjusting means for adjusting print density of the predetermined color into first print density when the received print information is judged to be the first type and for adjusting print density of the predetermined color into second print density when the received print information is judged to be the second type, the second print density being higher than the first print density; and print means for printing the predetermined color of the received first type of print information at the first printing density and for printing the predetermined color of the received second type of print information at the second printing density.
According to a further aspect, the present invention provides a printing device, comprising: input means for receiving print information; a print head for being driven, in response to a driving pulse signal, to print the received print information onto print medium; driving means for selectively supplying either first driving pulse signals or second driving pulse signals to the print head in correspondence with successive sets of print information, each first driving pulse signal for printing a corresponding set of print information being comprised of at least one pulse, the second driving pulse signal for printing a corresponding set of print information being comprised of a plurality of successive pulses, the number of the pulses in the second driving pulse signal being greater than the number of puls

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