Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Reexamination Certificate
1998-08-05
2001-03-20
Pendegrass, Joan (Department: 2852)
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
C399S299000
Reexamination Certificate
active
06204867
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a color image forming apparatus of a laser scanning type wherein multiple laser scanning units are used to form color images based on a color digital image signal.
(2) Description of the Prior Art
In a color image forming apparatus, for example, in a color digital copier, the image of a color original input through its scanner is subjected to predetermined image processings and the image data which has been obtained by separating the input image into its color components and color conversion thereof, is reproduced for each of the colors so that the color printer portion produces a reproduced image of the color original. Further, recently, in order to achieve high-speed reproduction of color images at high resolution, color digital copiers which incorporate an image forming apparatus employing laser scan recording technology have been put on the market.
In these color digital copiers, multiple laser deflection scanning units are provided for individual recording portions so that the laser beam for each color, being modulated in accordance with the digital image signal, is brought to sweep the corresponding photoreceptor, thus forming a static latent image for image forming. Such a laser deflection scanning unit mainly comprises a polygonal mirror and a motor for driving the polygonal mirror at a high speed of rotation.
However, in this color digital copier, the polygonal mirrors in the laser deflection scanning units are driven at high speed, which causes problems with respect to the motor's life and the problem of whirring due to air-turbulence caused by polygonal mirror rotating etc.
To solve these problems, it is disclosed in Japanese Patent Publication Hei 4 No. 49,688, that when laser recording is not effected, the motors for rotating the polygonal mirrors are retarded to a slower speed than when it is in operation or the motors are spun down with the drive of the motor completely stopped. However, in this configuration, the motors need to be controlled so as to completely recover the predetermined speed of rotation in a short period of time, in order to activate the laser recording portions, to revert from the waiting state back to the operating state in which the laser recording portions can effect image recording.
Further, in recent color digital copiers, a recording portion for black (BK) is generally provided in addition to Y(yellow), M(magenta) and C(cyan) recording portions in order to improve black reproduction and hence enhance the total color reproducibility of the color image. Therefore, color digital copiers have been put on the market which have the monochrome mode other than the color mode so as to allow for monochrome copying as well as color copying.
Also in a digital color copier of this type, if all the mirror-driving motors of the laser deflection scanning units in the recording portions are designed to rotate whenever a copying operation is to be done regardless of the mode, either color or monochrome mode, the mirror-driving motors for color will be also driven even in the monochrome mode. Resultantly, the problem of the life of the mirror-driving motors and their noise problem still remain unsolved.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a color image forming apparatus in which the life of the mirror-driving motors is extended and the problems of their noise and wasted power consumption are reduced. Further, the operational efficiency of the color image forming apparatus is improved by reducing the acquisition time of the first copy.
The color image forming apparatus of the present invention achieves these and other objects by the provision of configurations of elements having the following aspects. The advantages of each of these aspects will appear more fully below.
In accordance with the first aspect of the invention, the color image forming apparatus includes image information input means for inputting image information. The apparatus also includes a laser recording means having a plurality of laser scanning units corresponding to the component colors of the input image information. The scanner units are arranged in parallel with one another. In addition, each scanner unit includes a laser, a rotational polygonal mirror and a drive motor for driving the rotational polygonal mirror.
Laser scan control means for governing the drives of the drive motors such that laser scanning may be performed in accordance with input image information also are included in the color image forming apparatus. In addition, image forming means having a plurality of image forming units for the respective component colors of the input image information are provided. These image forming units are arranged in parallel with each other such that each image forming unit may form an image from the latent image recorded on the photoreceptor by the corresponding laser scanning unit.
Finally, the color image forming apparatus further includes image discrimination means for detecting the color type of the image information input through the image information input means.
It is a first feature of the invention that in the combination of elements just described the laser scan control means, based upon the result determined by the image discrimination means, controls the drive of the driving motor in each laser scanning unit in accordance with the component color to be used.
In accordance with the second aspect of the invention, the color image forming apparatus having the above first feature also includes a second feature having two parts. Specifically, the image discriminating means determines whether the image is of color or monochrome from the image information input through the image information input means. In addition, the laser scan control means performs control so that the driving motors of the laser scanner units for recording color images are stopped or retarded when the image discriminating means has determined that the original image is a monochrome image.
In accordance with the third aspect of the invention, the color image forming apparatus having the above first feature also includes a third feature having two parts. Specifically, the image discriminating means determines whether the image is of color or monochrome from the image information input through the image information input means. In addition, the laser scan control means performs control so that the driving motor other than those of the laser scanner units for recording color images is rotated in the predetermined condition.
In accordance with the fourth aspect of the invention, the color image forming apparatus includes image information input means for inputting image information. The apparatus also includes a laser recording means having a plurality of laser scanning units corresponding to the component colors of the input image information. The scanner units are arranged in parallel with one another. In addition, each scanner unit includes a laser, a rotational polygonal mirror and a drive motor for driving the rotational polygonal mirror.
Laser scan control means for governing the drives of the drive motors such that laser scanning may be performed in accordance with input image information also are included in the color image forming apparatus. In addition, image forming means having a plurality of image forming units for the respective component colors of the input image information are provided. These image forming units are arranged in parallel with each other such that each image forming unit may form an image from the latent image recorded on the photoreceptor by the corresponding laser scanning unit.
Finally, the color image forming apparatus further includes mode managing means for checking usage-frequencies of processing modes implemented by the apparatus in the past. The processing modes include a first processing mode in which the image information input through the image information input means is processed as color image information, and a second proc
Fujimoto Osamu
Manabe Nobuo
Oda Ayuma
Yamanaka Toshio
Yoshiura Syoichiro
Conlin David G.
Dike Bronstein, Roberts & Cushman LLP
Pendegrass Joan
Sharp Kabushiki Kaisha
Tucker David A.
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