Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1998-09-03
2001-08-07
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S009000, C347S005000, C347S010000, C347S011000, C347S017000
Reexamination Certificate
active
06270180
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet printer, and specifically to an ink jet printer usable as a hard copy apparatus in which an image data from a computer is recorded by a jet of ink.
Conventionally, in a printer in which recording is conducted by binary gradation data, ON/OFF recording is conducted corresponding to binary data.
For example, in an ink jet printer, image data for each one-jetting of each nozzle of a print head having a plurality of jet nozzles is transferred to a driving IC of the head for each time, and ink-jetting is conducted by transferred image data and an image is formed.
FIG. 11
is an illustration showing a drive signal waveform supplied to a head and conditions of jetting a drop of liquid in a jet nozzle, as a model. As shown in
FIG. 11
, the following processes are repeated by the drive signal waveform, in which a jetting nozzle composed of a piezo-element, or the like, is expanded ({circle around (1)}→{circle around (2)}), then, contracted ({circle around (3)}) and jets a drop of liquid of ink, and returns again to an initial condition ({circle around (4)}).
Recently, gradation recording is conducted in various types of printers, and conducted also in an ink jet printer in the same manner as other printers.
As a gradation recording method, there is a method in which the number of dots jetted for a pixel is changed. According to this method, by changing the number of dots to be jetted, the same effect can be obtained as that obtained when dimensions of a dot at jetting are changed.
Incidentally, there is sometimes a case where a sufficient jetting can not be conducted when viscosity of ink is changed by the temperature change. In this case, ink jetting can not be accurately conducted, resulting in a decrease of image quality.
Generally, viscosity is increased two times every time when temperature decreases by 10° C. Therefore, when an ink jet printer is used in the low temperature environment such as early in the morning in winter, sufficient ink jetting can not be carried out for a period of time after the start of the printer.
Further, even if the ink jet printer is warmed up after its start, the temperature of ink of unused color is not increased, thereby, sufficient ink jetting can not be carried out.
Further, the head is in an air-cooled condition by the movement of the head, the temperature of the unused color ink tends to be lowered. Further, even in the used color ink, the overall head is in the water-cooled condition when the cooled ink passes through the nozzle, and therefore, the temperature is hardly increased.
Due to such the problems, a proposal is made in Japanese Patent Publication Open to Public Inspection No. 133062/1984, in which the ink is heated by providing a heater near the head of the ink jet printer.
However, when the heater is provided as described above, there are following problems:
(1) the number of parts is increased near the head, and the structure becomes complicated;
(2) it is difficult to widely control heating of the ink in a liquid accommodation chamber in the head;
(3) efficiency is low when the heating of the ink in a liquid accommodation chamber in the head is widely controlled;
(4) power consumption due to a heater resistance body is large.
Further, in the ink jet printer having heads for a plurality of colors for color image formation, a problem also occurs in which color balance is lost if the temperature of each head is not almost the same. Further, it is extremely difficult to maintain the head temperature of each color uniform even when the heating control by the above-described heater is applied.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above problems and to provide an ink jet printer in which bad influence upon the image caused by the change of the ink viscosity due to temperature can be avoided while refraining the structure of the head from being complicated.
The invention as a means for solving the problem will be described below.
(1) An ink jet printer which conducts image recording by jetting liquid drops of ink from a leading end of a nozzle of a head, comprising: a drive signal generating means for generating a drive signal to jet the ink according to image information; a piezoelectric means for applying pressure onto a liquid accommodation chamber according to the drive signal; a temperature measuring means for measuring the temperature of the head; and a heating signal generating means for generating a heating signal to heat the ink in the liquid accommodation chamber by generating a heat by vibration by the piezoelectric means.
That is, in this invention of the ink jet printer, the ink in the liquid accommodation chamber adjacent to the piezoelectric means is heated by thermal conduction from the piezoelectric means heated by the heating signal applied to the piezoelectric means, without a jet of liquid drops from the leading end of the nozzle.
Accordingly, the piezoelectric means for jetting the ink is used also for heating the ink, thereby, bad influence upon an image caused by the change of the ink viscosity due to the temperature can be avoided, without providing any outside fitting part for heating near the head.
(2) The ink jet printer according to Item (1), wherein the heating signal generating means generates the heating signal at the time of non-recording.
That is, in this invention of the ink jet printer, the ink in the liquid accommodation chamber adjacent to the piezoelectric means is heated by thermal conduction from the piezoelectric means heated by the heating signal applied to the piezoelectric means, at the time of non-recording, without a jet of liquid drops from the leading end of the nozzle.
Accordingly, the piezoelectric means for jetting the ink is used also for heating the ink, and the ink is heated at the time of non-recording, thereby, bad influence upon an image caused by the change of the ink viscosity due to the temperature can be avoided, without providing any outside fitting part for heating near the head.
(3) The ink jet printer according to Item (1), wherein the heating signal generating means generates the heating signal when the head exists outside the image formation area.
That is, in this invention of the ink jet printer, the ink in the liquid accommodation chamber adjacent to the piezoelectric means is heated by thermal conduction from the piezoelectric means heated by the heating signal applied to the piezoelectric means when the head exists outside the image formation area, without a jet of liquid drops from the leading end of the nozzle.
Accordingly, the piezoelectric means for jetting the ink is used also for heating the ink, and the ink is heated when the head exists outside the image formation area, thereby, bad influence upon an image caused by the change of the ink viscosity due to the temperature can be avoided, without providing any outside fitting part for heating near the head.
(4) The ink jet printer according to Items (1) to (3), wherein the heating signal generating means controls the amplitude of the heating signal according to the measurement result of the temperature measuring means.
That is, in this invention of the ink jet printer, the ink in the liquid accommodation chamber adjacent to the piezoelectric means is heated by thermal conduction from the piezoelectric means heated by the heating signal whose amplitude is changed corresponding to the temperature, without a jet of liquid drops from the leading end of the nozzle.
Accordingly, the piezoelectric means for jetting the ink is used also for heating the ink, and the ink is heated by the heating signal whose amplitude is controlled, thereby, bad influence upon an image caused by the change of the ink viscosity due to the temperature can be avoided, without providing any outside fitting part for heating near the head.
In this case, because the amplitude is proportional to energy, the energy for heating is increased by increasing the amplitude. Accordingly, when the amplitude of the heating signal is controlled,
Arakawa Hiroaki
Asano Kazuo
Horiyama Takashi
Maekawa Yoshikazu
Barlow John
Do An H.
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Konica Corporation
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