JPS6113754A - 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 a constant so as to separate all chromatic signal levels from the achromatic signal levels. CONSTITUTION:A dichroic mirror 40 reflects the light of the G component and transmits the beams of B and R components. The outputs of the CCD41 and 42 are equal to [M] and [G] respectively. Then the output of the CCD42 is inverted to satisfy a/(a+b)=k (o<k<1), where (a) and (b) means optional constants. Then a synthetic signal satisfying a [M]+b[G'] is shown in a figure B. If 0<k< 2/3 is satisfied, all 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. Ruru.

2. Prior Art Conventionally, as color image processing, for example, color printing, electrophotography, image signal processing of color scanners, etc. are known. All of these use three primary colors (
It is necessary to obtain three color information by color separation of "blue B, green G, red R)". For example, according to a known full-color process electrophotographic copying machine, for example, after corona charging the photoreceptor, The original image is exposed through a red filter, developed with a cyan developer, and the resulting cyan visible image is temporarily transferred onto copy paper. Next, the photoreceptor is exposed through a green filter in the same manner as above, and developed with magenta. After developing with a dye, transfer a magenta visible image onto the same copy paper in alignment with the cyan image.Furthermore, repeat the same process as above using a blue filter and yellow developer to align it with the previous two images. Then, if necessary, fix the final color image of the print.

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 stage of plate making for each color, an uncorrected color separation negative image is overlaid with a separation positive image of the required density created from another color separation negative image. We are making 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. Techniques are known for modifying the first electrostatic charge image by applying a charge stream of opposite polarity. For example, magenta color can be reproduced by this, but this is only a way of correcting the color. 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.

3. Purpose of the Invention The purpose of the present invention is to sharply produce images consisting of chromatic colors and achromatic colors.
To provide a method that is highly accurate, controllable, and easily reproducible.
be.

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 an optical means, multiplies the signal level of each of these image information by an arbitrary constant, and synthesizes it. the optical means are selected such that the signal levels of are separable from the achromatic signal levels, and the constants are selected such that all of the chromatic signal levels are separable from the achromatic signal levels. It is characterized by this.

According to a preferred embodiment of the invention, different color information 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 44 is exposed to light of color A1, an output signal of color information [n] is output. Similarly, by exposing with A7 color light, an output signal of color information [n] can be obtained. These output signals may be the potential of the photoreceptor, or may be the output voltage or current of the light receiving element, and such output signals may be caused not only by exposure C by light in different wavelength ranges as described above. , can also be obtained by filtering the light from the original. When combining the two types of color information described above, one of the color information, for example, [A,] is inverted to form [A,] 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 [n)+(Ax), chromatic color levels are separated on either side of an achromatic color 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), cyan (C), and blue (B). ), green (Q'), and red (R).

Next, Fig. 3 shows that the method of the present invention is applied to a distance of 1 m.
1 is a schematic diagram of main parts of an example of a color image forming apparatus used. In this apparatus, an electrostatic latent image forming means 3
1, image exposure is applied to a pattern corresponding to an original image or a document (not shown), and 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 produced by developing devices for each color arranged around the photosensitive drum 1] 3A, 13B, 13C... (actually, as many developing devices as the number of colors desired to be reproduced are arranged). However, in the drawing, three developing units are shown as an example.) The development delay name is sequentially applied to each color or mixed color. After the visualized toner images of each color are formed on the photoreceptor drum 1, and before the toner images are transferred, the exposure lamp 33 irradiates the area of the photoreceptor drum 1 where the toner images have been formed, and the transfer device 34 The recording paper fed from the P paper feeder (not shown) (its path is indicated by the broken line 35)
This toner image is transferred to the paper (shown by ). The recording paper is heat-fixed in a fixing device 36 that includes at least one heated roll, and is 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 by the cleaning that was canceled during the toner image formation. It is removed by device 38.

In the color image forming apparatus described above, the latent image forming means 3
1 (for example, a laser light source) K 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 is guided to the dichroic mirror 40 through the lens 39, where the light 32 in each predetermined wavelength range is
It is divided into 2a and 32b. Each of the elements 32a and 32b is a solid-state image sensor, for example, a CCD (ChargeCouple).
pled Device: Charge-coupled device) 41,
42, and each CCD output is obtained. These are then input to the image signal processing section 43, but at this time,
For example, the output level of the CCB 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 G and yellow Y1 as shown in the figure.
Chromatic color image parts consisting of red R, magenta M, blue B, cyan C, and white W.

It is assumed that each image portion of an achromatic color consisting of black is included. The light 32 corresponding to this original image is, for example, B
, -The light enters a dichroic mirror 40 that reflects the G component light and transmits the R component light.

As a result, light consisting of B and G components enters the dichroic mirror 4 and 1 due to the incidence of light in each wavelength range.
c CCD 42 and light consisting of R component enter fcC
The output levels shown in the figure can be obtained from the CD 41, respectively. Among these outputs, the output [C] from the C0D 42 is inverted as shown in the image signal processing unit 43 (the inverted signal is written as [C]), and then the output [C] from the C0D 42 is inverted as shown in the figure.
is combined with the output (R) from

Then, based on this composite signal ((R) + (C)), the latent image forming means 31 irradiates the photosensitive drum 1 with a light amount corresponding to the level of each color (image exposure). On the photosensitive layer of the photosensitive 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 levels (G, B) on both sides of the achromatic level (w, b).
, C) and a second group of chromatic levels (M, Y, R) are formed, which are separable from the achromatic levels. 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).
The shaded area in the figure represents the developable area (the same applies hereafter).

Here, during the above signal synthesis, each output (R) and [C
] shall be multiplied 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 9 as follows. .

Image section G Y RM B Cw b (R)10001101 (C:]　　　-]LLo-!--!-t1　.

(However, the difference between the W level and the b level is assumed to be 1.

) Therefore, the composite signal: a(R)+b(:C) can be expressed as follows.

Image part GYRMB-Cwb Here, the absolute values of a and b are arbitrary, and only the ratio matters.9, a:b=:(1-k), and the above composite signal is as follows. It can be expressed as follows.

Image part GYRMBCwb This relationship is plotted on the horizontal axis and on the vertical axis kCR)+(x-kXC
) is shown in Figure 5 (A). In this figure, the shaded area is the achromatic color level (the same applies hereinafter). For example, if there is a gray (f) on the original manuscript,
If there are two image parts of ), each output of is obtained corresponding to each gray image part. However, fIFi gray close to white,
1 is a gray close to black. If the composite signal of each of these outputs is represented by K in Fig. 5(A), then Fig. 5(A)
) is indicated by a dash-dot line.

That is, all achromatic color levels are represented by straight lines passing through (!-, !-) in the diagram and included in the above-mentioned diagonally shaded area.

As understood from FIG. 5(A), at the same time as selecting the filter characteristics of the dichroic filter 40, the values of the constants a and b are selected, and if -y<k('1), all chromatic colors (G, Y, R, M, B.

The signal level of C) can be separated from the level of achromatic colors (w, b).

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

Therefore, the outputs of each C0D41 and 42 are as shown in the figure, and among these, the output of CCD42 is inverted and becomes CG).
1, the other output CM), this composite signal (a(M)+b(G), or k(M)+(
x−k)CG)) is as follows.

GYRMBCwb If this composite signal is illustrated, it will be as shown in Figure 5 (B), and if 0(k =b=1
(k=i)).

FIG. 7 shows another example in which a half mirror is provided in place of the dichroic mirror 40 described above, and 32a
A green filter GF and a neutral density filter ND are arranged in the optical path of the filter 132b (however, this N
(D filter is not required).

Therefore, as shown in the figure, the output (N) 5ζ from C0D42
The output CG) is obtained from the CCD 4'l, and if the output [N] is inverted and the two are combined, chromatic color levels G, C, Y and R, M, B are obtained on both sides of the achromatic color levels w and b. are all separated.

This composite signal (a (G) + b (N), mafCti
k(G)+(4-k)(N))tj, which can be expressed as follows.

Image part G Y RMB Cwb b 2b b 2b b2b a(G)+b[N) T T a+-Hr)ya-
1-H1ba-1-k 2-2k l+2k 2+k
1+2 to 2-2kk[G:)+(1k)[N] a 3
3-cho-cho 1l-kk This is shown in FIG. 5(C), but 1.
(If k(1), then all chromatic levels can still be separated on either side of the achromatic level (ie, the example of FIG. 7 is awl, b=1 (k=7)).

FIG. 8 shows an example in which a magenta filter is used as the filter on the CCD 41 side in FIG. 7, and the output signal (a(M)+bcio, or k(M)+( 1-k)(N)) is obtained. In this case, if 2<sc<-, all chromatic color levels can be separated from achromatic color levels (in the example of Fig. 8, a
:=1, b=1).

Image part GYRMBCwb Next, in the example of Fig. 4, if a neutral density filter ND is used for the CCD41111, a composite signal ((N) + (1-k) (C)) obtained in the same way
It becomes possible to separate the bell.

FIG. 9 shows a hidden gem with the filter function reversed in FIG. 4 (that is, the mirror 40 reflects the B1G component light and transmits the B1G component light). Therefore, the composite signal (k[c)+
(1-k) R) can separate the chromatic level from the achromatic level as shown in FIG. 5(E). In this case, for example, in the example shown in FIG. 9 (a=3.b=), all of the examples shown in FIGS. Solid-state image sensor, e.g. C
(as a CD output), and these are synthesized.
curvature, as a combination of other outputs, a[Y:]+bCB)
(a combination of a yellow filter and a blue filter), etc. are possible. In addition to the laser light source, the latent image forming means 31 may be a light source using an LED, LCD, ECD, etc., or an electrostatic recording means using a multi-stylus, an ion control electrode, etc., an inkjet,
Direct printing means using a heat-sensitive recording head or the like may be used instead of the means 31 described above. In the case of an inkjet method, etc., there is no need for the developing device shown in FIG. 39, and images can be directly recorded on recording paper.

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

According to this example, a half mirror 50 is arranged in the path of light from the original image, and the reflected light from the half mirror 5075 is made to enter the photoreceptor drum l via the filter 51. The transmitted light of the fumirror 50 is made to enter the C0D53 through the filter 52'', and the CCD
After the output is processed by the image signal processing unit 54, K, ? JL/
The image information transmitted through the filter 51 such as a stylus or ion control electrode and the recording means 55 are stored in the image signal processing section 5.
4, synchronization is achieved on the photoreceptor 1.

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 over the entire surface, from the original G, Y, C, and W portions, and selects the negative charges on the surface. make it disappear.

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, each chromatic color level G, Y separated on both sides of the white level W and the black level b as shown in the figure. , 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.

FIG. 12 shows 1+IIe which is divided into FIG. 11 and uses a red filter as the filter 51 and a cyan filter as the filter 52, and in the same way, the separation of all chromatic color levels from the achromatic color level becomes fiJ function. .

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. 13, a reciprocating document table 61 is provided at the top of the main body of the apparatus, and a document 44 placed on the document table 61 is illuminated by an illumination lamp 62.

63 and 64 are mirrors, 3gFi fixed lenses, and 47 is a movable dichroic filter that reflects a predetermined chromatic color light and passes light of a complementary color to this chromatic color, which can be inserted into and exited from the optical path. It is now possible to do so. A photosensitive layer 56 is provided on the surface of the drum-shaped photoreceptor 1, and when the photoreceptor 1 rotates clockwise, the photosensitive layer 56 is uniformly charged by a corona charger. The photosensitive layer 5G is made of selenium, an organic semiconductor, or the like.

Around the photoreceptor 1, there are a charger 24 that uniformly charges the photoreceptor layer 56, and a developer 48 and 49 that contain a large amount of toner of each color.
...(However, actually aG, Y, R, M, B.

Arrange the developing device for the desired color among C and b, but in the drawing, Fi
Two developing units are shown as an example. ) 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.

Also, around the outside of the drum 17, there is a screen charger path and a screen charger 69 made of an EL (electroluminescence) plate or an AC corona charger to remove the charge remaining on the photosensitive screen drum 17. and a charged particle source (corona discharger) 19 that projects loaded particles onto a position facing the photoreceptor 1 inside the photosensitive screen drum 17.

As part of the photosensitive screen 17 is shown in FIGS. 14A and 15A, the photosensitive screen 17 is a conductive screen 1 made of stainless steel or the like having a large number of fine openings 1o and having one side exposed.
1, an insulating layer 13 made of methacrylic resin or the like provided on the other side of the conductive screen, and an AJ? The photoconductive layer 15 is composed of a bias conductive layer 14 made of azo dye, selenium dye, 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. 14B.
Furthermore, other known layer configurations may also be employed.

FIG. 15 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 Figure 15A,
The photoconductive layer 15 is negatively charged over the entire photosensitive screen 17 by the charger 28, and then, as shown in FIG. Next, as shown in FIG. 15C, when positive ion particles are projected onto the photosensitive screen 17 from the charged particle source 19, the positive ion particles pass through the negatively charged area of the screen 17. , adheres in a predetermined amount in a predetermined pattern on the photosensitive layer 56 to form a positive electrostatic latent image. In FIG. 150, Vt is a bias power supply, ■ is a discharge power supply, and vs is a DC power supply. .

FIG. 16 shows an example in which a photosensitive screen 17 with a two-layer structure different from the above is used, and the screen 17 after image exposure is
On the other hand, when negative ion particles are projected from the charged particle source 19 by the discharge power supply V,', the ion particles pass through the exposed region and form a negative electrostatic latent image (negative) on the photosensitive layer 56.

Next, an image forming process using the photosensitive screen 17, for example the screen shown in FIG. 15, 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 are negatively charged, and then imagewise exposed to light from the original material.

At this time, the dichroic mirror 47 reflects the G component light of the reflected light from the original to produce B and R components.
Use one that has the function of transmitting the light of the component.
As a result, the photosensitive screen 17 and the photosensitive layer 56 have the following properties:
As shown, a predetermined amount of negative charge is left in the predetermined pattern. Then, when positive ion particles are projected from the charged particle source 19, the positive ion particles are transferred to the photosensitive screen 17.
passes through the negatively charged region and reaches the photosensitive layer 56;
A new combined electrostatic charge image is formed by the negative charges on the photosensitive layer 56 and the positive charges that have passed through the photosensitive screen 17 (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 17J are combined, the particle source 19 The polarity of the image information [G] is reversed by the positive ion particles from , resulting in composite information CM)+[:G:].

FIG. 18 shows a case where the dichroic mirror 47 in FIG. 17 is one that reflects the R component light and transmits the B and G component lights. It is possible to separate the chromatic color levels.

Although the present invention has been exemplified 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 Fi to be combined, and the optical means may be changed in various ways for this purpose. 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 provides that when multiple pieces of image information obtained by optical means are multiplied by an arbitrary constant and synthesized, the chromatic color level can be separated from the achromatic color level at the same time as the optical means. Since this is selected, six images can be formed with chromatic colors and achromatic colors, and chromatic colors clearly separated from each other. Therefore,
A desired image can be reproduced clearly, with high precision, and with easy control.

[Brief explanation of the drawing]

The drawings show examples of the present invention, and FIG. 1 is a basic process diagram during image formation.
, (to), , C) are spectral diagrams of each color of light, Figure 3 is a schematic diagram of the image forming device, and Figure 4 is a process diagram during image formation using the device in Figure 3. , Figures 5 (A), (B), (Q, Plow, (G), ■ are graphs showing each composite signal, Figures 6 and 7, Figures 8 and 9 are graphs showing other image formation Figure 10 is a schematic diagram of another image forming apparatus, Figures 11 and 12 are process diagrams of image formation using the apparatus in Figure 10, and Figure 13 is a diagram of still another image forming apparatus. A schematic diagram of the apparatus; FIGS. 14A and 14B are enlarged sectional views of a portion of the photosensitive screen; FIGS. 15A, 15B, and 15C are process diagrams of an image forming process using the photosensitive screen; FIG. 16 The figure is a step-by-step diagram of an image forming process using another photosensitive screen, and Figures 17 and 18 are process diagrams of image forming using the apparatus shown in Figure 13. In, 1...Photosensitive drums 13A, 13 drums 13C, 48, 49...Developer 17...Photosensitive screen 19...Charged particle source 31 .55...Latent image forming means 40.47...Dichroic mirrors 41, 4
2.53...CCD (charge coupled device) 43.
54...Image signal processing section 44...Original image or original 51.52...Filter 56...Photosensitive layer. Agent Patent Attorney Hiroshi Aisaka (nm) (C) Stl, & (nm) (nm) Fig. 2' Liquid length (nm) (D) Oyo (nm) 5t4= (nm) Fig. 5 in one piece

Claims (1)

[Claims] 1. A plurality of image information is obtained from the original image by optical means, and the signal level of each image information is multiplied by an arbitrary constant and synthesized. selecting the optical means to be separable from the signal level;
and selecting the constant so that all of the chromatic color signal levels are separated from the achromatic color signal levels. 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 combined.