Electrophotography – Image formation – Development
Reexamination Certificate
2000-03-01
2001-07-31
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Development
C347S047000, C399S238000
Reexamination Certificate
active
06269232
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an apparatus for jetting liquid and, more particularly, to a developing apparatus used when an electrostatic latent image is developed with liquid in a copying machine, an electrophotographic printer, or the like.
BACKGROUND ART
Hitherto, several attempts have been made to achieve a method for developing an electrostatic latent image by turning liquid ink into spray ink utilizing ultrasonic wave or static electricity and selectively applying it onto the electrostatic latent image with electrostatic power.
For example, in the art described in Japanese Patent Publication (examined) No. 52-7936 and Japanese Patent Publication (examined) No. 55-20230, a concave vibrator excites an ultrasonic wave in developing solution, and the developing solution is jetted from an opening portion of a container for storing the developing solution. Particularly, in the art described in Japanese Patent Publication No. 55-20230, the excitation by an ultrasonic wave is supplemental and an electric field from the electrostatic latent image causes a mist to generate from the developing solution. In the art described in Japanese Patent Publication (unexamined) No. 4-337772, a surface acoustic wave generated in a piezoelectric member forming a comb electrode jets a developing agent existing in the edge of the piezoelectric member.
Further, in the art described in Japanese Patent Publication (unexamined) No. 5-333703, standing-wave vibration of a transverse wave is excited in a member connected with a piezoelectric vibrator, thereby turning an ink supplied thereon into a mist, and the mist is charged by a grid electrode. Further, in the art described in Japanese Patent Publication (unexamined) No. 9-319229, a charged ink mist is sent to a developing position by a fan and is applied onto the electrostatic latent image.
However, in the Japanese Patent Publication (examined) No. 52-7936, the ultrasonic wave has a frequency of 20 to 30 kHz, and diameter or size of ink particles is large and their momentum is large. Therefore, developing solution is applied onto portions where any latent image does not exist (causing thereby so-called “scumming” and “fog”). As any particular jetting spout is not provided therein, it is impossible to efficiently decrease the particle size (particle diameter) by increasing the frequency of the ultrasonic wave. Furthermore, in the art described in Japanese Patent Publication No. 55-20230, it is impossible to increase generation amount of mist attracted with the power of the electric field of the electrostatic latent image, and it is difficult to attain a record of high speed and high density.
In the art described in Japanese Patent Publication (unexamined) No. 4-337772, manufacturing a mechanism for generating a surface acoustic wave requires a high processing accuracy, and the apparatus is not provided with any jetting spout. It is therefore suspected that the particle size of the developing solution varies widely.
In the art described in Japanese Patent Publication (unexamined) No. 5-333703, the apparatus becomes complicated and large in order to circulate ink with a pump and install the grid electrode. Further, since the apparatus uses a standing wave of a transverse wave, when particle size is decreased by shortening the wavelength, it is difficult to uniformly decrease them, eventually resulting in occurrence of scumming and. Moreover, depressed portions on the grid electrode are stained with ink, and periodical cleaning is necessary.
Particularly in Japanese Patent Publication (unexamined) No. 9-319229, the apparatus becomes complicated and large in order to convey ink mist with a fan and install a dielectric charged electrode. Moreover, it takes a lot of time from the generation of the ink mist until it is ready for developing because the ink mist is conveyed with the fan. It is very difficult to control density of the mist on the basis of the printing density and control start/stop for jetting the mist.
DISCLOSURE OF THE INVENTION
Accordingly, the invention was made to solve the above-discussed problems, and has an object of providing a liquid jetting apparatus of simple construction, in which maintenance is easy, and uniform liquid-drops can be generated at high speed and high density.
Another object of the invention is to provide an electrostatic latent image developing apparatus in which density is adjusted according to time lag from generation of liquid-drops to development and to printing density.
The foregoing objects and advantages are achieved by providing a new and improved liquid jetting apparatus including:
a container for storing liquid to be jetted and having a jetting spout for jetting said liquid to be jetted; and
a sound wave generation source which is arranged opposite to the jetting spout on said container and introduces a sound wave, in which a set of n (≧2) pulses of a predetermined cycle forms a lump and two such lumps adjacent to each other are divided by a period having no pulse of said predetermined cycle or longer, into the liquid to be jetted;
wherein said jetting spout has an opening width of not less than 2m (m is a maximum value of n with respect to all of said lumps of pulses) times of a wavelength of a surface traveling wave of the liquid to be jetted excited by said sound wave.
The present invention provides an electrostatic latent image developing apparatus including:
a container for storing liquid to be jetted and having a jetting spout for jetting said liquid to be jetted;
a sound wave generation source which is arranged opposite to the jetting spout on said container and introduces a sound wave, in which a set of n (≧2) pulses of a predetermined cycle forms a lump and two such lumps adjacent to each other are divided by a period having no pulse of said predetermined cycle or longer, into the liquid to be jetted; and
a latent image carrier where an electrostatic latent image is produced and moves;
wherein said jetting spout has an opening width of not less than 2m (m is a maximum value of n with respect to all of said lumps of pulses) times of a wavelength of a surface traveling wave of the liquid to be jetted excited by said sound wave, and develops said electrostatic latent image by selectively applying the liquid to be jetted onto the electrostatic latent image.
The present invention also provides an electrostatic latent image developing apparatus including:
a latent image carrier where an electrostatic latent image is produced and moves;
a container for storing liquid to be jetted and having a jetting spout for jetting said liquid to be jetted;
a sound wave generation source which is arranged opposite to the jetting spout on said container and introduces a sound wave, in which a set of n (≧2) pulses of a predetermined cycle forms a lump and two such lumps adjacent to each other are divided by a period having no pulse of said predetermined cycle or longer, into the liquid to be jetted; and
a liquid jetting apparatus for developing said electrostatic latent image by selectively applying the liquid to be jetted onto the electrostatic latent image;
wherein density of the electrostatic latent image is detected from a picture signal on which the electrostatic latent image is based, and amount of said liquid jetted by said liquid jetting apparatus in a unit time is controlled on the basis of said density.
The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is for purpose of illustration only and is not intended as a definition of the limits of the invention.
REFERENCES:
patent: 6154235 (2000-11-01), Fukumoto et al.
patent: 6155671 (2000-12-01), Fukumoto et al.
patent: 6182907 (2001-02-01), Nakagawa et al.
Aizawa Jyun-ichi
Fukumoto Hiroshi
Ozaki Yasuhiko
Chen Sophia S.
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
Tran Hoan
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