JPS6113753A - Image forming method - Google Patents

Abstract

PURPOSE:To reproduce an image containing chromatic and achromatic colors with high sharpness, high accuracy and easy control, by selecting an optical device so that the chromatic signal level can be separated from the achromatic signal level. CONSTITUTION:The output levels shown in the figures are obtained by the incidence of light of each wavelength band given from a dichroic mirror 40 and through a CCD42 on which the light containing the BG component is made incident and a CCD41 on which the light containing the R component is made incident respectively. The output [C'] given from the CCD42 is inverted at a signal processing part 43 and synthesized with the output [R] given from the CCD41. Based on this synthetic signal, the beams of light quantities corresponding to each color level are irradiated to a photosensitive drum from a latent image forming circuit. Thus latent images of each color corresponding to the potentials corresponding to the synthetic signal waveform are formed to a photosensitive layer of the drum. For these latent images, the chromatic levels (G, B and C) of the 1st group and the chromatic levels (M, Y and R) of the 2nd group are formed at both sides of the achromatic levels (w and b). These chromatic levels can be separated from the achromatic levels.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention relates to an image forming method, particularly an image reading method and printer copying method for simple color discrimination between chromatic colors and achromatic colors, or between chromatic colors. 2. Prior Art Conventionally, as color image processing, for example, color printing, electrophotography, image signal processing of color scanners, etc. are known. In all of these, it is necessary to obtain three color information by color separation of the three primary colors (Blue, B, Green, Green, and Red) for image formation. For example, according to a known full-color process electrophotographic copying machine, for example, after a photoreceptor is charged with corona, an original image is exposed through a red filter, developed with a cyan developer, and the resulting cyan visible image is once placed on copy paper. Transfer to. Next, the photoreceptor is exposed with a green filter in the same manner as above, and after development with a magenta developer, a magenta visible image is transferred onto the same copy paper in alignment with the cyan image. Further, the same process as above is repeated using a blue filter and a yellow developer, and the image is transferred to match the previous two images. Then, if necessary, the final color image of the print is fixed.

On the other hand, masking technology, which is a color correction method in color printing, is known as image processing based on two color information. For example, according to the positive masking method, at the platemaking stage for each color, an uncorrected color separation negative image is superimposed with a separation positive image of the required density created from another color separation negative image. , making color corrections.

A technique in which such a masking method in printing is applied to electrophotography is disclosed in Japanese Patent Application Laid-Open No. 52-3430. According to this known technique, a first electrostatic charge image is formed on a photoreceptor, a second electrostatic charge image is formed on a photosensitive screen, and a first electrostatic charge image is formed in accordance with the second electrostatic charge image. A technique is known in which the first electrostatic charge image is corrected by irradiating a charge flow with a polarity opposite to that of the first electrostatic charge image. For example, magenta color can be reproduced by this, but this is only based on the premise of color correction. Therefore, it is not intended to separate chromatic colors from achromatic colors, and in particular it is not possible to separate chromatic color levels on either side of an achromatic color level.

38 Purpose of the Invention The purpose of the present invention is to make images consisting of chromatic colors and achromatic colors clear and
The object of the present invention is to provide a method that is highly accurate, controllable, and easily reproducible.

4. Structure of the invention, that is, the image forming method according to the present invention obtains a plurality of image information from an original image by optical means, multiplies the signal level of each of these image information by an arbitrary constant, and synthesizes it. It is characterized in that the optical means is selected so that the signal level can be separated from the achromatic color signal level.

According to a preferred embodiment of the present invention, different color information [+), [A2] from the original image are inversely related to each other.
By combining the chromatic color information can be separated into both sides of the achromatic color level. One way to bring out the different color information mentioned above is to expose the original to light in different wavelength ranges. For example, as shown in FIG. 1, when the original is exposed to light of color A□, an output signal of color information [A□] is extracted. Similarly, by exposing with A2 color light, an output signal of color information [A2] can be obtained.

These output signals may be the potential of the photoreceptor, or the output voltage or current of the light receiving element, and such output signals may be generated not only by exposure to light in different wavelength ranges as described above, but also by exposure to light in different wavelength ranges as described above. It can also be obtained by filtering the light from the When combining the above two types of color information, one of the color information, for example [A2], is inverted to form [A2] as shown in FIG.
Here, "inversion" may be a positive-negative relationship, or refers to a state in which the electrical polarity is reversed.

In such composite information, for example [AI]+[A2], chromatic levels are separated on either side of an achromatic level.

5. Examples Embodiments of the present invention will be described in detail below with reference to the drawings.

First, in order to understand the color characteristics of the various filters used in the following examples, Figure 2 shows the reflectance of each color of light: yellow (Y), magenta (M), shea (C), blue ( B), green (G), and red (R).

Next, FIG. 3 is a schematic diagram of essential parts of an example of a color image forming apparatus used to carry out the method of the present invention. In this apparatus, the photoreceptor drum 1, which has been uniformly charged by a scorotron charger, is subjected to image exposure in a pattern corresponding to an original image or a document (not shown) by an electrostatic latent image forming means 31. An electrostatic latent image is formed. This electrostatic latent image is composed of image information synthesized so that the chromatic color level and the achromatic color level can be separated as described later based on the present invention. Therefore, this electrostatic latent image is transferred to the developing device 1 for each color, which is arranged around the photoreceptor drum 1.
3A, 13B, 13C...(Actually, there are as many developing units as the number of colors you want to reproduce, but in the drawing there are 3 developing units.
Each color or a mixture of colors is sequentially developed using O) shown as an example. After the toner image of each color visualized in this way is formed on the photoreceptor drum 1, and before the image is transferred, the exposure lamp 33 irradiates the area of the photoreceptor drum 1 where the toner image has been formed, and the transfer device is rotated. Paper feeder (not shown)
Recording paper sent from (its route is indicated by broken line 35)
This toner image is transferred to. The recording paper is heat-fixed in a fixing device 36 that includes at least one heated roll, and then discharged outside the machine.

On the other hand, after the transfer has been completed, the photosensitive drum 1 is neutralized by the static eliminator 37, which was not used during the toner image formation, and the excess toner remaining on the surface is removed during the toner image formation. It is removed by a cleaning device 38.

In the color image forming apparatus described above, the latent image forming means 3
1 (for example, a laser light source) is supplied with an output obtained by processing image information based on reflected light (or transmitted light) 32 from an original image as follows.

That is, the reflected light 32 passes through the lens 39 and is guided to the dichroic mirror 40, where the light 32 in each predetermined wavelength range is
It is divided into 2a and 32b. Each party 32 a
, 32b are solid-state image sensors, for example, CCD (C
41 and 42, and each CCD output is obtained. These are then input to the image signal processing unit 43, at which time, for example, the output level of the CCD 42 is inverted and combined with the output of the other CCD 41.
This composite signal is sent to the latent image forming means 31, and an electrostatic latent image corresponding to the composite signal is formed on the photosensitive drum 1.

To explain this in detail with reference to FIG. 4, the original image 44 has green color G1 yellow color Y1 as shown in the figure.
It is assumed that each chromatic image portion includes red, R1, magenta, M1, blue, B1, and cyan C, and each achromatic image portion, consisting of white, w1, and black. The light 32 corresponding to this original image reflects, for example, B and G component light, and R
The light enters a dichroic mirror 40 that transmits the component light.

The CCD 42 that has been
41, output levels as shown in the figure can be obtained, respectively. Among these outputs, the output from CCD42 [C
] is inverted in the image signal processing section 43 as shown in the figure.
The inverted signal is written as [C]) and is further combined with the output [R] from the other CCD 41.

Then, based on this composite signal ((R)+[C), the latent image forming means 31 irradiates the photoreceptor drum 1 with a light amount corresponding to the level of each color (image exposure). On the photosensitive layer of the drum 1, electrostatic latent images of each color are formed with potentials corresponding to the composite signal waveform shown in FIG.

The resulting composite signal or electrostatic latent image has a first group of chromatic colors L/H (G,
B-, C) and the second group of chromatic color levels (M, Y, R), which can be separated from the achromatic color level. Therefore, by developing the chromatic colors of the first group and the second group separately based on the achromatic color level, it is possible to obtain a color image of a desired color (single color or mixed color) (see Fig. 4). The shaded area represents the developable area (the same applies hereafter).

Here, during the above signal synthesis, each output [R] and (C
) by an arbitrary constant as shown below.

Composite signal -a [R:]+b (C) (However, a and b are constants: in the example of Fig. 4, a=, b=1) And the level of each image part of each output is as follows. be.

Image part G Y RM B Cw b (:R) 10001101 (C) --o --11° (However, the difference between W level and b level is taken as 1) Therefore, composite signal: a [R) +b[C:] can be expressed as follows.

Image part G YRM B Cw b a[R]+b[te] (a”8) Connection 0: (a+*%
a+b) b aHere, the absolute values of a and b are arbitrary, and only their ratio matters. f rank = k (If we set o(k(1), then b −= 1− k a+ba: b=k: (1-k) The above composite signal can be expressed as follows.

Image part GYRMBCwb -z+k t-k z-kx+k kCR]+(1-k)[C]-10T-T-11-kk
This relationship is plotted on the horizontal axis as k[:R]+(1-kX
If C) is taken and shown, it becomes as shown in FIG. 5(A). In this figure, the shaded area is the achromatic color level (the same applies hereinafter). For example, if a gray (
If there are two image parts of g, corresponding to each gray image part, gs : (R(gθ)=-1(C(gθ)=Dinggz:
[R(gz))=7s EC(gz))=7 outputs are obtained. However, g□ is a gray close to white, and g2 is a gray close to black. The composite signal of each of these outputs is
In the case shown in Figure (A), k(R(gt):)+(4-k
XC(gx))=temperature, as shown by the dashed line in FIG. 5(A).

That is, all achromatic color levels are represented by straight lines included in the above-mentioned hatched area through (212) in the figure.

FIG. 6 shows the dichroic mirror 40 in FIG.
An example is shown in which a filter having a function of reflecting G component light and transmitting BXR component light is used.

Therefore, the outputs of each C0D41 and 42 are as shown in the figure, and when the output of CCD42 is inverted to [G] and combined with the other output CM), this composite signal (a[
M)"bl:G), or k [IvD + (1-
k) CG)) is as follows.

Image part G Y RMB Cw b aCM)+b(G) (a+b)(: ”b) : Q
: (8+b) b a button button <□) side 1' (1
-Y(0)(1-Kamado-kk) When this composite signal is illustrated, as shown in Fig. 5(B), the chromatic color level can be separated from the achromatic color level with 0<k. (i.e.,
In the example of FIG. 6, a=b=1 (k=ding), )0 FIG. 7 shows the output of the CCD 42 described above in the example of FIG.
When inverting GE, the signal that is inverted so that the dynamic range of the signal becomes A (the output level after inversion is T (G), the output after this inversion - CG) is CC
When combined with the output CM of D41, a composite signal with a level partially different from that in FIG. 6 is obtained.

That is, green level G and magenta level M are selectively separated above and below black level b and white level W, respectively.

FIG. 8 shows another example in which a half mirror is provided in place of the above-mentioned dichroi and kumira shank, 32a,
A green filter GF and a neutral density filter ND are arranged in the optical path of the filter 32b (However, this N
D filter is not necessary) 0 Therefore, as shown in the figure, C
Output [N] is output from CD42, and output C is output from CCD41.
G) is obtained, and if the output [N] is inverted and the two are combined, chromatic color levels G, C,
Y, R, and MXβ are separated.

This composite signal (a[G)+b(N:], or k(G)
+(1-k) [:N)) can generally be expressed as follows.

Image part G Y RIVi B Cw b ・CG)+bし）ki(...b-伽・Kaise)埜b・kl
l+G'3 double 1-kXN': ldan' Mori and granulation
-kk This is shown in Figure 5(C), but it is also possible to separate chromatic levels on either side of the achromatic level (
In the example of FIG. 8, a=b'=1).

FIG. 9 shows an example in which a magenta filter is used as the filter on the CCD 41 side in FIG. 8, and the output signal (a[R4]+G Y
RM B Cwb Next, in the example of Fig. 4, if a neutral density filter ND is used on the CCD 41 side, the synthesized signal (k(N) + (1-k)[:C)) obtained in the same way is The result will be as shown in Figure 5 (E).

In all of the examples shown in FIGS. 3 to 9 above, a plurality of 4 iii! ? Obtain iron information digitally (as a solid-state image sensor, e.g. CCD output),
These are synthesized. Of course, other output combinations can be considered, such as a[Y)+b[B:] (a combination of a yellow filter and a blue filter). Also,
As the latent image forming means 31 described above, in addition to the laser light source, a light source using an LED, LCD, ECD, etc. may be adopted, or an electrostatic recording means using a multi-stylus, an ion control electrode, etc., an inkjet, a thermosensitive Direct printing means using a recording head or the like may be used instead of the means 31 described above. In the case of an inkjet method, the developing device shown in FIG. 3 is not necessary, and images can be directly recorded on recording paper.

Next, referring to FIG. 10, another image forming apparatus will be explained. However, in this example, parts common to those in FIG. 3 are given common reference numerals and their explanations are omitted.

According to this fII+c, a half mirror 5o is arranged in the path of light from the original image, and the reflected light from the half mirror 50 is made to enter the photosensitive drum l via the filter 51, while the light transmitted through the half mirror 5o is The light is made to enter the CCD 53 via the filter 52, and after the CCD output is processed by the image signal processing section 54, it is made to be input to an electrostatic recording means 55 such as a multi-stylus or an ion control electrode. When a recording signal is output from the recording means 55 to the photoreceptor drum, the image information transmitted through the filter 51 and the recording means 55 are synchronized on the photoreceptor 1 in the image signal processing section 54 .

To explain this process using FIG. 11, the above filter 5
By using a green filter as 1, light enters the photosensitive layer 56 of the photosensitive drum 1, which has already been negatively charged on the entire surface, from the original G, YXC, and w parts, and selectively removes the negative charges on the surface. Extinguish.

On the other hand, by using a magenta filter as the filter 52, an output as shown in the figure is obtained from the CCD 53, which is processed by the image signal processing section 54 and applied to the electrostatic recording means 55 or the photoreceptor. Convert to ionic current. Then, when the recorded information by the recording means 55 and the image information on the photoreceptor are combined on the photoreceptor, as shown in the figure, each shoulder coloring level G, Y separated on both sides of the white level W and the black level b is obtained. , C, R, M, and B are obtained, respectively.

In the examples shown in FIGS. 10 and 11, a plurality of pieces of image information are obtained digitally on one side and analogously on the other, but the two pieces of image information have positive and negative potentials on the photoreceptor. This is an inversion relationship in that the relationship is the same as in the previous example.

Next, an example in which the present invention is applied to an image forming apparatus using a photosensitive screen will be described.

As shown in FIG. 12, a reciprocating document table 61 is provided at the top of the main body of the apparatus, and the document material placed on the document table 61 is illuminated by an illumination lamp 62.

63 and 64 are mirrors, 39 is a fixed lens, and 47Iri is a movable dichroic filter that reflects a predetermined chromatic color light and allows light of a complementary color to the chromatic color to pass through. I'm starting to get it.
A photoreceptor layer 56 is provided on the surface of the drum-shaped photoreceptor 1, and when the photoreceptor 1 rotates clockwise, the photoreceptor layer 56 is uniformly charged by a corona charger. The photosensitive layer 56 is made of selenium, an organic semiconductor, or the like.

Around the photoreceptor 10, there are a charger u1 for uniformly charging the photosensitive layer 56, a developing device 49, which stores toner of each color, and a
・・・・・・・・・(However, in reality, G, Y, R, M,
BXC.

A developing device for a desired color among those shown in b is arranged, and two developing devices are shown as an example in the drawing. ) etc. are arranged.

On the other hand, a cylindrical photosensitive screen drum 17 is disposed on the outside of the photosensitive drum 1 so that the photoconductive layer faces, and this drum 17 is rotated counterclockwise in synchronization with the document table 61 and the photosensitive layer 56. It is arranged so that it can rotate in the direction.

In addition, around the outside of the drum 17, there is a screen charger section and a screen static eliminator made of an EL (electroluminescence) plate or an AC corona static eliminator for removing the electric charge remaining on the photosensitive screen drum 17. 69, and a charged particle source (corona discharger) 19 that projects charged particles to a position facing the photoreceptor 1 inside the photosensitive screen drum 17.

'The photosensitive screen 17, as a part of which is shown in FIGS. 13A and 14A, consists of a conductive screen 11 made of stainless steel or the like having a large number of fine openings 10 and one side exposed, and a conductive screen 11 made of stainless steel or the like with one side exposed. An insulating layer 13 made of methacrylic resin or the like provided on the other surface, and a conductive layer 14 for bias such as M provided on this insulating layer by vapor deposition or the like.
and a photoconductive layer 15 made of azo dye, selenium, amorphous silicon, cadmium sulfide, zinc oxide, or the like.

Note that the photosensitive screen 17 may have another structure, for example, it may have a layered structure as shown in FIG. 13B.
Furthermore, other known layer configurations may also be employed.

FIG. 14 shows a process of selectively depositing charges on the photosensitive drum 1 using the photosensitive screen 17 to form a positive latent image. First, as shown in FIG. 14A, between the chargers The photoconductive layer 151c is negatively charged over the entire photosensitive screen 17, and then the negative charge is selectively eliminated or reduced by image exposure 32, as shown in FIG. 14B.

Next, as shown in FIG. 14C, when positive ion particles are projected onto the photosensitive screen 17 from the charged particle source 19,
Positive ion particles pass through the negatively charged area of the screen 17 and are deposited in a predetermined amount on the photosensitive layer 56 in a predetermined pattern.
Forms a positive electrostatic latent image.

Note that ■□ in FIG. 14C is a bias power supply, v2 is a discharge power supply, and ■3 is a DC power supply.゛Figure 15 shows an example in which a photosensitive screen 17' having a two-layer structure different from the above is used, and the screen 1 after image exposure is
When negative ion particles are projected from the discharge power source 19 onto the photosensitive layer 7', the ion particles pass through the exposed area and form a negative electrostatic latent image (negative) on the photosensitive layer 56. do.

Next, an image forming process using the photosensitive screen 17, for example the screen shown in FIG. 14, will be explained with reference to FIG. However, in this figure, the screen is shown schematically.

First, the entire surface of the photosensitive screen 17 and the photosensitive layer 56 is negatively charged, and then imagewise exposed to light from the original document.

At this time, the dichroic mirror 47 used has the function of reflecting the G component of the light reflected from the original and transmitting the B and R components. As a result, a predetermined amount of negative charges are left on the photosensitive screen 17 and the photosensitive layer 56 in a predetermined pattern as shown. Next, when positive ion particles are projected from the charged particle source 19, the positive ion particles pass through the negatively charged area of the photosensitive screen 17 and reach the photosensitive layer 56, causing the negative charges on the photosensitive layer 56 to be and the positive charges that have passed through the photosensitive screen 17 to form a new combined electrostatic charge image (the bias of the photosensitive screen 17 is omitted in the drawing). As a result, a positive or negative polarity charge is selectively left on the photosensitive layer 56 with a predetermined amount of charge, and a positive chromatic color level and a negative polarity level are left on both sides of the achromatic color levels W and b. An electrostatic latent image is formed in which the colored levels are separated.

In this process, when the charge image (image information [M]) on the photosensitive layer 56 after image exposure and the charge image (image information [G]) on the photosensitive screen 17 are combined,
The polarity of the image information [G] is reversed by the positive ion particles from 9 and becomes composite information (M)+[G].

Although the present invention'f has been illustrated above, the embodiments described above can be further modified based on the technical idea of the present invention.

For example, there may be three or more types of image information to be combined, and for this purpose the optical means may be changed in various ways. Furthermore, the method of synthesizing image information is not limited to the method described above.

6. Effects of the Invention As described above, the present invention selects an optical means such that all chromatic color levels can be separated from achromatic color levels when multiple image information obtained by optical means is multiplied by an arbitrary constant and synthesized. Therefore, six images can be formed with chromatic colors and achromatic colors clearly separated from each other. Therefore, a desired image can be reproduced clearly and with high precision and with easy control.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIG. 1 is a basic process diagram at the time of image formation, and FIG. 2 (G) and (B)
, (Ql(6), (G), (G) are each spectrum diagram of each color of light, Figure 3 is a schematic diagram 1 of the image forming apparatus, and Figure 4 is the image forming time using the apparatus shown in Figure 3. The process diagram in Figure 5, (6), (Ql(2), and (g)) are graphs showing each composite signal, and Figures 6, 7, 8, and 9 are graphs for other image formation. Figure 10 is a schematic diagram of another image forming apparatus, Figure 11 is a process diagram of the first image forming apparatus.
FIG. 12 is a schematic diagram of another image forming apparatus; FIGS. 13A and 13B are enlarged cross-sectional views of a portion of the photosensitive screen; FIG. FIG. 14B and FIG. 140 are process diagrams of an image forming process using a photosensitive screen. Fig. 1s is a step diagram of an image forming process using another photosensitive screen, and Fig. 16 is a process diagram of image forming using the apparatus of Fig. 12. In addition, in the symbols shown in the drawings, 1......Photosensitive drum 13A,
13 B, 13 C, 4B, 4'l...
...Developer 17...Photosensitive screen 19...Charged particle source 31.55... ...Latent image forming means 40.47
-=-Dichroic mirror 41.42.53...
・・・・・・CCD (charge coupled device) 43.54
・・・・・・・・・Image signal processing components・・・・・・・・・
...Image or manuscript addressed to Orishina 51.52...
・・・・・・Filter 56・・・・・・・・・・・・
It is a photosensitive layer. Agent Patent Attorney Hiroshi Aisaka (A) Icho (nm) (C) 4th T (nm) Wokeflea (nm) 2 Figure 5F? , & (nm) 5r length (nm) 840 ''' (nrn) Fig. 12 Fig. 13A Fig. 138 Fig. 14A Fig. 14C q Fig. 15 q Fig. 16

Claims (1)

[Claims] 1. A plurality of image information is obtained from the original image by optical means, and the signal level of each of these image information is multiplied by an arbitrary constant and synthesized. At this time, all chromatic color signal levels are nullified. An image forming method characterized in that the optical means is selected so as to be separable from the color signal level. 2. The method as claimed in claim 1, wherein a chromatic color level is formed on both sides of an achromatic color level. 3. The method according to claim 1 or 2, wherein the plurality of image information includes image information that is in an inverse relationship to each other at least when they are combined.