JPH0522232B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a color image forming apparatus that reproduces images of color originals. Conventionally, electrophotographic methods and inkjet methods have been typically used to form color images. In electrophotography, color originals are generally printed in red, green,
The colors are separated using a blue color filter, and a latent image is formed on a charged photosensitive drum in each color in accordance with the original, which is developed and transferred to recording paper. A similar process is applied to the other materials to reproduce color images. In this case, since the black portion of the document is reproduced by mixing cyan, magenta, and yellow toners, reproducibility will be extremely poor if there is color shift. In particular, most of manuscripts for office work are black, which poses a big problem in practical use. On the other hand, in a color image forming method using an inkjet method, a document is separated into colors using a color filter or the like, and amounts corresponding to the intensities of the colors are stored in a memory. Thereafter, ink is ejected from each color nozzle according to the contents of the memory to reproduce a color image. In this method, the black parts of the document can be calculated by performing logical calculations during the color separation process. In addition, by not ejecting ink from the nozzles for other colors, it is possible to reproduce an easy-to-read image without color shift for black areas. However, this method requires a large amount of memory to color separate the original and store the image information, and especially for office manuscripts where most of the parts are written in fine print, bandwidth compression is required. Even if the memory size increases, the memory size will not be reduced much. Another problem is that it takes time to form a copied image because each nozzle scans the surface of the paper to be copied. Furthermore, as for image forming apparatuses capable of obtaining color images, electrophotographic image forming apparatuses are generally more expensive than inkjet image forming apparatuses. Therefore, there is a need for a recording device that can produce color images at a lower cost and at higher speed. That is, the electrophotographic method allows color images to be obtained faster than the inkjet method, but is more expensive.On the other hand, the inkjet method is cheaper than the electrophotographic method, but the speed at which color images can be obtained is slow. There is also a problem. Furthermore, conventionally, there are devices that combine two electrophotographic recording means, or a combination of an electrophotographic recording means and an inkjet recording means. However, these systems can only record two to three colors at most, and although they are inexpensive devices, they can form images that can reproduce color originals at high speed and as high-quality full-color images with no color shift. There was no equipment. The present inventor has solved the above-mentioned problems by combining the advantages of the electrophotographic method and the inkjet method, and has also solved the problems that may arise at that time, thereby completing the present invention. It's ivy. SUMMARY OF THE INVENTION In order to eliminate the above-mentioned conventional problems, it is an object of the present invention to provide a color image forming apparatus that is capable of reproducing a color original as a high-quality image without color shift, while having an inexpensive apparatus configuration. Another object of the present invention is to provide a color image forming apparatus capable of preventing inkjet recording defects caused by an inkjet recording means due to the heat of a recording medium after thermal fixation by an electrophotographic recording method. Furthermore, the present invention provides a color image forming apparatus that can improve the overall recording throughput and reproduce the image of a color original when using an apparatus configuration including an electrophotographic recording means and an inkjet recording means each having a different recording speed. The purpose is to In order to achieve the above-mentioned object, the present invention includes a reading means for reading an original image, an information processing means for processing information of the read original image,
an electrophotographic recording means for recording only the black information of the original image on a recording medium; a recording medium standby means for waiting the recording medium on which the black information has been recorded by the electrophotographic recording means; and the information processing means. an inkjet recording means for recording color information other than black of the document image on the recording medium based on the information processed by the inkjet recording means; A configuration including a conveyance means for conveying the recording medium was adopted. Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows the principle of the color image forming method according to the present invention as a block diagram. First, in step S1, an original is set on the original platen, and then,
In step S2, the original is passed through red, green, and blue color filters, and a color image of the original is read by a sensor sensitive to each color. A circuit that implements this is illustrated in Figure 2, and the light that has passed through the red filter 1, green filter 2, and blue filter 3 is detected by a sensor (for example, composed of a CCD) that senses each color.
1a, 2a, and 3a, and when the amount of light of each color becomes larger than a predetermined value, a signal of "0" is generated, which is input to the NAND gate 4 and AND gates 1b, 2b, and 3b, respectively, and the cyan color memory 5a, The data are stored in the magenta color memory 5b and the yellow color memory 5c, respectively. In this case, each of the memories 5a to 5c stores information obtained by removing black image information from the image information obtained when the image is passed through the red filter 1, green filter 2, and blue filter 3. This corresponds to step S3 in FIG. Subsequently, as shown in step S4, only the black portion of the original image is copied using a normal electrophotographic method. Next, ink jets eject cyan, magenta, and yellow inks onto the recording paper on which only black has been copied, according to the signals stored in each memory.
Reproduce images other than black (step S5). An apparatus embodying such a color image forming method is illustrated in FIG. In FIG. 3, a color original 10 containing black characters is placed on an original platen 12. This original 10 is illuminated by a light source 13, and the surface of the original is scanned by an optical system or by moving the original. In addition, there are red, green, and
Image sensor 14 (second
(corresponding to filters and sensors 1 to 3 and 1a to 3a in the figure) are arranged to read the color portions of the image. The read image information is processed by a logic circuit (corresponding to the circuit in Figure 2) to remove black information, and then separated into cyan, magenta, and yellow color information, which corresponds to each memory in Figure 2. memory 15
is memorized. Further, at the same time, the light irradiated onto the document table 12 passes through the optical system 32 and forms an image on the photoreceptor 17. This photoreceptor 17 is mounted on a cylindrical aluminum base 16 with Se.
-It is composed of a deposited film of about 40 μm of Te, with a weight ratio of Te of about 20%, and has a characteristic of being sensitive to the entire visible light range. This photoreceptor 17 is charged to approximately +500 V by a corona charger 18, and is then exposed to an image of the original that has passed through the slit 33 as the drum rotates. At this time, the potential of the part that is not irradiated with light, that is, the black part of the original, is +400V.
On the other hand, the area irradiated with light becomes approximately +100V or less. The electrostatic latent image thus formed is visualized by a developing roller 19 to which developing toner is attached. Thereafter, the image on the photoreceptor 17 is transferred to the paper feed roller 21.
A transfer charger 2 is placed on the recording paper 22 that is sent through the
The inkjet image is transferred to the inkjet section via the conveyance roller 23 after being fixed by the heat roller 27. After the image corresponding to the black part of the original is reproduced on the recording paper in this way, the photoreceptor 17 is cleaned by the blade 25, and then the entire surface is irradiated by the lamp 26 to remove the residual charge, and the above-mentioned process is repeated. . Recording paper 2 that reproduces the black characters of the original in this way
Images other than black are reproduced by driving ink nozzles ink jet heads 28, 29, and 30 containing cyan, magenta, and yellow color inks on the printer 2 using signals from the memory 15 that stores image information. do. The inkjet nozzle used in this embodiment is, for example, the one described in Japanese Patent Application Laid-Open No. 54-59936, and as shown in an enlarged view in FIG.
A SiO ₂ oxide film 41 is formed, and a heating element 4 is placed on it.
2 is used. For example, a vapor-deposited film of HfB ₂ is used as the heating element, and both ends of the film are coated with Al.
For example, when a voltage of about +40 V is applied to HfB ₂ in response to a signal, it generates heat, and as described later, the supplied ink is ejected from the ejection port to form ink droplets. Note that a SiO ₂ film 43 made by CVD is formed on the surface of this HfB ₂ to protect the heating pair 42 . Moreover, a silicon wafer 44 on which an oxide film 45 is formed on the surface.
are stacked one on top of the other to form an inkjet nozzle. In this case, the two silicon wafers 40 and 44 are processed so that holes with a diameter of 40 μm are formed at a density of 16 holes/mm, and the heating element 42 is installed in these holes. There is. As shown in FIG. 6, such an ink jet nozzle is connected to an ink stopper 50 via a tank 52 and a pump 51, and ink is supplied to the nozzle. In such a configuration, when the drive circuit 49 is driven by a signal from the memory 15, the heating element 4
2 is heated, and as a result, the ink supplied from the ink pump 51 forms bubbles 46 on the surface of the heating element, and the pressure of the bubbles 46 forms ink droplets 47, which are ejected from the nozzle. At this time,
When the recording paper 22 is placed near the nozzles, ink droplets adhere to the recording paper 22. By using such an inkjet device, as shown in FIG. 3, cyan, magenta, and
Each of the three colors of yellow is sequentially reproduced to reproduce a color image. The ink used in the present invention had the structure shown in Table 1.

【table】

[Table] Examples of recording paper include high-quality paper commercially available as Ginkan and Seven Star (both trade names), medium-quality paper commercially available as Hakubotan (trade name), and Toyo Paper No. Although non-size paper commercially available as .4 (trade name) was used, good results were obtained with either recording paper. Furthermore, although this example uses an inkjet that generates ink droplets using thermal energy, it is not limited to this, and is described in U.S. Pat. No. 3,060,429.
Tele type method, U.S. Patent No. 3596275, No.
Needless to say, inkjet methods such as the Sweet method described in US Pat. No. 3,298,030, the Hertz method described in US Pat. No. 3,416,153, and the Stemme method described in US Pat. No. 3,747,120 can be used. In addition, in the above embodiment, an image including black text was explained, but for example, when a color is specified, ink of colors such as red and blue is ejected instead of overlapping each color. By doing so, it is possible to reproduce an image of that color. In this case, since the image is not reproduced by superimposing colors, an image with good resolution can be obtained. Furthermore, in each of the embodiments, after a color image is formed by synchronizing the reproduction of an image by electrophotography and the reproduction of a color image by an inkjet method, the next image is copied. When copying a large number of originals, as shown in FIG. 4, the recording paper on which black characters have been reproduced is once stored in the storage box 34, and then sent to the recording surface of the inkjet by the paper feed roller 35. High-speed recording becomes possible. Also, if you store the number of copies of the black part in memory together with the image information and prepare multiple storage boxes, after the black part has been copied, the next document can be copied in parallel with the inkjet recording of the previous image. High-speed image formation becomes possible. Furthermore, if the document is of a single color, for example, only black, by taking out the recording paper stored in the storage box 34 outside after forming a black image by electrophotography, the recording paper does not pass through the recording surface of the inkjet. , it becomes possible to form images at a recording speed comparable to that of a monochrome recording device. As described above, according to the present invention, it is possible to obtain a color image forming apparatus that can reproduce a color original as a high-quality full-color image without color shift, despite having an inexpensive apparatus configuration. Further, according to the present invention, it is possible to obtain a color image forming apparatus that can prevent inkjet recording defects by the inkjet recording means by cooling the recording medium after heat fixing by electrophotographic recording. Further, according to the present invention, there is provided a color image forming apparatus capable of reproducing color originals by improving the overall recording throughput when using an apparatus configuration using an electrophotographic recording means and an inkjet recording means each having a high recording speed. Obtainable. Further, according to the present invention, when recording a single color image, after recording by the electrophotographic recording means, the recording medium is kept on standby by the recording medium waiting means before being conveyed to the inkjet recording means. By removing the recording medium, it is possible to obtain a color image forming apparatus capable of forming images at a recording speed comparable to that of monochrome electrophotographic recording apparatuses.

[Brief explanation of the drawing]

Each figure shows an embodiment of the present invention.
FIG. 1 is a block diagram showing the principle of the method of the present invention.
Figure 2 is a circuit diagram showing the image processing logic circuit; Figure 3 is a circuit diagram showing the image processing logic circuit;
4 are block diagrams of the apparatus of the present invention showing different embodiments, FIG. 5 is a cross-sectional view showing the structure of the ink jet, and FIG. 6 is an explanatory diagram illustrating the driving of the ink jet nozzle of the present invention. It is. 1... Red filter, 2... Green filter, 3...
Blue filter, 10...Original, 12...Original table, 1
4...Sensor, 15...Memory, 17...Photoreceptor, 18...Charger, 19...Developing roller, 20
...Transfer charger, 28-30...Inkjet nozzle, 50...Ink tank.

Claims (1)

[Scope of Claims] 1. A reading means for reading an original image, an information processing means for processing information of the read original image, and an electrophotographic recording means for recording only black information of the original image on a recording medium. , recording medium standby means for waiting the recording medium on which the black information has been recorded by the electrophotographic recording means; and color information other than black of the document image based on the information processed by the information processing means. Color image formation characterized by comprising: an inkjet recording means for recording on the recording medium; and a conveyance means for conveying the recording medium from the electrophotographic recording means to the inkjet recording means via the recording medium standby means. Device. 2. The color image forming apparatus according to claim 1, wherein the inkjet recording means generates bubbles in the ink using thermal energy and ejects the ink.