Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-05-20
2004-03-30
Nguyen, Lamson (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S015000, C347S010000
Reexamination Certificate
active
06712450
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to an ink jet printer having a color head and a monochrome head, and more particularly to an ink jet printer that is switchable, during a single scanning operation, between a color printing mode by the color head and a monochrome printing mode by the monochrome head.
BACKGROUND ART
Up until now, a print head of an ink jet type includes a nozzle, a pressure chamber, an ink supply system, an ink tank and a piezoelectric element, and records characters or images on a recording medium, like paper, etc., allowing ink particles to be injected from the nozzle, after transmitting the displacement and pressure generated at the piezoelectric element to the pressure chamber.
FIG. 1
is a block diagram of the conventional ink jet printer. The ink jet printer comprises a control unit
200
and a head carrier
202
. To the control unit
200
, a CPU
206
to control the whole, a memory
208
, an interface
210
to connect to a host
204
, a controller
212
, an image memory
214
, a mechanical driver
216
to drive a mechanism
218
, and a drive waveform generation unit
220
are installed. To the head carrier
202
, a color head drive unit
222
, a monochrome head drive unit
224
, a color head
226
, and a monochrome head
228
are mounted. The monochrome or color image data sent from the host computer
204
to the control unit
200
is processed by the CPU
206
and written into the image memory
214
. Of these image data, the color image data is split into color components, Y, M and C, and written into the image memory
214
. When printing documents, etc. in the monochrome mode, the controller
212
sequentially reads monochrome data (K) from the image memory
214
, corresponding to the nozzle layout of the head, and supplies the data to the monochrome head drive unit
222
. As drive waveform data is already written in a waveform memory located in the controller
212
as monochrome drive waveform data, and the drive waveform data is continuously outputted to the drive waveform generation unit
220
, and supplied to the monochrome head drive unit
224
, after being converted into analog drive waveform. The monochrome data from the controller
212
is used to select drive waveform at the monochrome head drive unit
224
, and the selected drive waveform is supplied to the monochrome head
228
, so that the printer records characters or images on a record medium like the paper, etc., as the piezoelectric element drives ink particles to be injected from the nozzle.
Also, when printing color images, like photos or graphics, the conventional ink jet printer supplies a group of drive waveforms consisting of a plurality of drive waveforms corresponding to the number of intensities from the drive waveform generation unit
220
to the color head drive unit, based on the color waveform data written in a waveform memory of the controller, and further supplies them to the color head
26
, after selecting waveform of intensities corresponding to the individual color data of Y, M, and C, to print multi-intensity color image. On the other hand, when printing binary images, like monochrome characters or line-drawings, the conventional printer supplies a group of drive waveforms with improved degree of resolution to obtain sharp image, in short, it supplies drive waveforms having higher frequency than in the case of color images, so as to upgrade resolution.
However, in the ink jet printer, in which the monochrome printing and the color printing share the use of the conventional drive waveform generation unit
220
, if the printer must print the document
230
as shown in
FIG. 2
, in which the color photo
232
is inserted in the monochrome text
234
, the printer cannot print the monochrome text
234
and the color photo
232
simultaneously, by performing only a single head scanning. Therefore, the printer traditionally prints the monochrome text
234
while the monochrome head
28
is scanning once, as setting high resolution for monochrome scanning, and then, it prints the remaining color photo
234
with the color head
226
, in the same scanning position, after shifting to multi-intensity color scanning. Because of this, if monochrome text and color photo is intermingled while the head is scanning one stroke, the printer must divide scanning into two modes, multi-intensity color scanning and high-resolution monochrome scanning modes, thereby resulting in a problem that the printing speed can be reduced by half.
DISCLOSURE OF THE INVENTION
According to the ink jet printer of the present invention there is provided an ink jet printer that can print by a single scanning operation, even if monochrome images and color images are intermingled, to speed up the printing speed.
The present invention is directed to an ink jet printer comprising a color head having a plurality of nozzles arranged on a head carrier, each of the plurality of nozzles injecting color ink particles by the drive of a piezoelectric element; and a monochrome head having a plurality of nozzles arranged the head carrier, each of the plurality of nozzles injecting monochrome ink particles by the drive of a piezoelectric element; wherein the ink jet printer comprises a control unit which, within a single scanning of the head carrier, switches the printing mode between a color printing mode by the color head and a monochrome printing mode by the monochrome head, to thereby provide a control of printing. As described above, the ink jet printer in accordance with the present invention will be able to make simultaneous printing with high speed, switching between color image and monochrome image within a single scanning of the head carrier.
The control unit of the ink jet printer includes a color drive waveform generation unit which simultaneously generates a group of color drive waveforms representative of at least two types of color dots; a monochrome drive waveform generation unit which simultaneously generates a group of monochrome drive waveforms representative of at least two types of monochrome dots; a color data output unit which outputs color data for a single scanning from a color image, in synchronism with a single scanning of the head carrier; a monochrome data output unit which outputs monochrome data for a single scanning from a monochrome image, in synchronism with a single scanning of the head carrier; a color head drive unit which selects one waveform from the group of color drive waveforms, based on the color data, the color head drive unit supplying the selected one waveform to the piezoelectric element of the color head for the drive thereof; and a monochrome head drive unit which selects one waveform from the group of monochrome drive waveforms, based on the monochrome data, the monochrome head drive unit supplying the selected one waveform to the piezoelectric element of the monochrome head for the drive thereof. By virtue of this configuration of the control unit, in cases where color data and monochrome data are intermingled in the printing data for a single scanning of the head carrier, the control unit can select the color head drive waveform in response to the color data during the single scanning, and select the monochrome waveform drive signal in response to the monochrome data, to thereby provide a switching between the color printing mode and the monochrome printing mode. The color printing mode of the control unit is a multivalued intensity mode, and the monochrome printing mode of the control unit is a high-resolution mode in which the resolution of the monochrome head is integer times the resolution of the color head. As described above, the printer can ensure high quality image printing, as well as high-speed printing, as a result of setting the color printing mode to multivalued intensity mode, and the monochrome printing mode to high-resolution mode, even if color image including a full-color picture, etc., and monochrome image including line-drawing, etc. are intermingled. In the multivalued intensity mode of the control unit, the amount of ink parti
Fujitsu Limited
Nguyen Lamson
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