JPS6113758A - Image forming device - Google Patents

Abstract

PURPOSE:To reproduce a desired image with high clearness, high accuracy and easy control by synthesizing the chromatic color levels separably with the achromatic color levels according to plural pieces of image information obtained from an optical device and selecting a specific color level out of the synthetic information. CONSTITUTION:The output [Y] of a CCD41 on which the beams containing G and R components is synthesized with the signal [B] obtained by inverting the output [B] of a CCD42 on which the light containing the B component at a picture signal processing part 43. For such an obtained synthetic signal or an electrostatic latent image, the 1st group of chromatic color levels (M, B and C) and the 2nd group of chromatic color levels (G, Y and R) are formed at both sides of the achromatic color levels (w and b). These chromatic color levels of both groups can be separated from the achromatic color levels. The development bias voltage level is set at VD1 or VD2 in the next development process. As a result, only a blue level [B] or a yellow level [Y], for example, is selected. Then these selected colors only are developed selectively and can be formed into a visible image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to, for example, an image reading device, a printer/copying device, and the like for simple color discrimination between chromatic colors.

2. Prior Art Conventionally, for example, as color image processing, image signal processing such as color printing, electrophotography, color scanner, etc. is known. In all of these, it is necessary to obtain three color information by color separation of three primary colors (blue B, green G, red R) 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 copied. Transfer onto paper. 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 copying layer in accordance with the cyan image. Further repeat the same process as above using a blue filter and yellow developer.

Transfer to match the previous two images. Then, the final color image of the print is fixed by making it ugly as necessary.

On the other hand, a masking technique, which is a color correction method in color printing, is known as image processing that exposes two color information. For example, according to the positive masking method, at the stage of plate making for each color, an unmodified color separation negative image is superimposed with a separation positive image of the required density created from other color separation negatives and images. Color corrections are being made.

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 a first electrostatic charge image is modified by applying a charge flow of opposite polarity. For example, magenta can be reproduced by this method, 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.

3. OBJECT OF THE INVENTION An object of the present invention is to provide an apparatus that can reproduce a desired image clearly, with high precision, and with easy control from images consisting of chromatic colors and achromatic colors.

4. Structure of the Invention In other words, the present invention provides an optical means for obtaining a plurality of image information from an original image, and a synthesis means for synthesizing the plurality of image information so that the chromatic color level can be separated from the achromatic color level. and a selection means for selecting a specific color level from this composite information.

According to a preferred embodiment of the present invention, different color information [AI], [K2
), it is possible to separate the chromatic color information into both sides of the achromatic color level. One way to extract 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 A9 color, the color information (Al3
The output signal of is extracted. Similarly, by exposing with A2 color light, an output signal of color information (Ai) 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, as shown in Figure 1, one of the color information,
For example, [A1] is reversed to form [A2]. child,
Here, "inversion" may be a positive-negative relationship;
Alternatively, it refers to a state where the electrical polarity is reversed. In such composite information, for example (AI) + (Ag), chromatic levels are separated on either side of an achromatic level. For example, by setting the developing bias VDI or VD2 for the composite information at the time of development, a desired chromatic color level can be selected and a desired color can be selectively reproduced.

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

FIG. 2 is a schematic diagram of essential parts of an example of a color image forming apparatus based on the present invention. In this apparatus, a scorotron charger 3
The electrostatic latent image forming means 31 exposes the photosensitive drum 1 uniformly charged to 0 in a pattern corresponding to an original image or a document (not shown), thereby forming an electrostatic latent image. . 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 formed by developing devices 13A, 13B, 13C for developing each color arranged around the photoreceptor drum 1 (actually, as many developing devices as the number of colors desired to be reproduced are arranged).
In the drawing, three developing units are shown as an example. ) to develop each color or a mixture of colors sequentially. After the toner image of each color visualized in this way is formed on the photoreceptor drum 1, before the image is transferred, the exposure lamp 33 irradiates the area of the four-photoreceptor drum 1 where the toner image has been formed, and the transfer device 34 This toner image is transferred onto a recording paper (its path is indicated by a broken line 35) fed from a paper feeder (not shown). The recording paper is
At least one sheet is heated and fixed by a fixing device 36 constituted by a heated roll, and then the sheet is discharged outside the machine.

On the other hand, the photoreceptor drum 1 after the transfer has been 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 process that was removed 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, LED, LCD, ECD) 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 ink mirror 40 through the lens 39, where the light 32 in each predetermined wavelength range is
a, 32°b. i light amount 2a, 32'b
are solid-state image sensors, such as CCD (Charge
CoupledDevjce: Charge-coupled device) 4
1.42, and each COD 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.
, red R1 magenta M, blue B1 cyan C, and achromatic image parts consisting of white W and black. The light 32 corresponding to this original image reflects, for example, B component light, and G, R component light.
The light enters a guichroic mirror 40 that transmits the component light. As a result, due to the incidence of light in each wavelength range from the guichroic mirror 40, the CCD 42 receives light consisting of the B component, and the CCD 42 receives light consisting of the G and R components.
41, output levels as shown in the figure can be obtained, respectively. Among these outputs, the output (E) from the CCD 42 is inverted as shown in the figure by the image signal processing unit 43' (the inverted signal is denoted as CB), and is further combined with the output (Y) from the other CCD 41. Ru.

Based on this composite signal ((Y)+(B)), the latent image forming means 31 irradiates the photoreceptor drum 1 with light of an amount corresponding to the level of each color (image exposure), thereby causing the photoreceptor to 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 levels (M, B,
C) and the chromatic color level of the second group (G.

Y, R) are formed and are separable from the achromatic color level.

Then, for the next development, the development bias (voltage) is set to vDl.
Or, if it is set to VB, for example, only the blue level (B) or yellow level (Y) is selected, and only these colors can be selectively developed and visualized (the diagonal lines in Figure 3). The area represents the developable area (same as the bottom two sides).

In order to selectively select a specific color level in this way,
As shown in FIG. 2, each developing device, for example 13A, 13B
, DC voltages vDI and VDI2 are applied between the developing sleeves 45A and 45B and the ground level, respectively. In this case, one developing device 13A is charged with negatively charged toner, and the other developing device 13B is charged with negatively charged toner.
contains positively charged toner.

Various methods of applying the developing bias can be considered, but for example, as shown in FIG.
Alternatively, vo can also be selected respectively.

Figure 5 shows the output level of the CCD 42 (CB) which is inverted so that the signal range is A (the output level after inversion is 'A (
B) ), and the output % (B) after this inversion is calculated by CCD4
1(7) output (Y), a composite signal with a level partially different from that in FIG. 4 is obtained.

That is, only the blue level B and the yellow level Y above and below the black level b and the white level W are separated. These are furthermore positively selected and developed by bias VDI or VO2.

FIG. 6 shows another example, in which a half mirror is provided in place of the above-mentioned gikroic mirror 40, and 32b
, 32a, a filter CF that transmits cyan color and a filter MF that transmits magenta color are arranged, respectively. Therefore, as shown in the figure, an output (C) is obtained from the CCD 42 and an output (M) is obtained from the CCD 41. If the output (C) is inverted and the two are combined, the achromatic color level w
, b are separated into chromatic color levels G, C and R, M.

These are furthermore reliably selected and developed by bias VDI or V2.

In all of the examples shown in Figures 2 to 6 above, multiple pieces of image information are obtained digitally (as output from a solid-state image sensor, e.g., CCD) from the original image of the document, and nine pieces of information are synthesized. be. Of course, other possible combinations include (R) + (C) (a combination of a red filter and a cyan filter), [Y] + [TE] (a combination of a yellow filter and a cyan filter), etc. Also,
As the latent image forming means 31 described above, in addition to the laser light source, a light source using an LED, LCDXECD, etc. may be employed.

FIGS. 7 and 8 show an example in which constant charge charging is used instead of the above-mentioned developing bias as means for selecting a specific color level.

That is, after forming composite information on the photoreceptor 1 in the same manner as described in FIGS. 2 and 4 above, a constant charge charging electrode (
For example, the entire surface of the photoreceptor 1 is negatively charged by a corona charger 47. As a result, as shown in Figure 8, the potential of the entire composite information decreases, and only the yellow level (Y) shows positive polarity, so this can be selectively removed by negative polarity toner during the next development. It can be visualized.

Next, another image forming apparatus will be explained with reference to FIG.

However, in this example, parts common to those in FIG. 2 are given common reference numerals and their explanations are omitted.

According to this example, a half mirror 50 is disposed 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 1 via the filter 51. A filter 52 transmits the transmitted light.
After the CCD output is processed by an image signal processing unit 54, it is input to an electrostatic recording means 55 such as a multi-stylus or an ion control electrode. When outputting a recording signal 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 by the image signal processing section 54.

To explain this process using FIG. 11, the above filter 5
By using a blue filter as 1, light enters the photosensitive layer 56 of the photosensitive drum 1, which is already entirely negatively charged, from the original B, M, C, and W parts, and selects the negative charges on the surface. make it disappear. On the other hand, the filter 5
By using a yellow filter as 2, the CCD
53 provides an output as shown in the figure, which is processed by an image signal processing section 54 and converted into a voltage applied to the electrostatic recording means 55 or an ionic current to the photoreceptor. 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 M, B separated on both sides of the white level W and the black level b, as shown in the figure. , C and GXY, R are obtained, respectively. Furthermore, among these levels, the blue level (
B) and yellow level [Y] are selected and developed. For this purpose, as shown in FIG.
A switch 46 that can select I, VDZ may be provided. Each DC bias V. AC bias power supply AC+ or AC2 can be connected to V1 or V112, respectively. When this AC bias is also applied, the developer is loosened by the action of an alternating electric field generated in the development area, and effects such as improvement in image density can be obtained.

In the examples shown in FIGS. 9 to 11, a plurality of pieces of image information are obtained digitally on one side and analogously on the other.
The two pieces of image information have an inverted relationship in that they have positive and negative potentials on the photoreceptor.

FIGS. 12 and 13 show still another example, in which the above-mentioned color level selection is performed by an image signal processing section 43 that performs inversion and composition of image information. Therefore, heavy charge charging means as described above is not provided.

That is, in the image signal processing section 43, the composite signal (Y) + CB) is obtained as in FIG.
As shown in the figure, of each color level, levels other than the blue level [B] and the yellow level (Y) are cut. For this purpose, the signal processing section 43 is provided with a comparator, and the reference voltage v
A specific signal level CB) or [Y
] is selected.

These selected signal levels are then fully amplified by an amplifier.

Then, based on this amplified signal, the latent image forming means 3
1, a corresponding electrostatic latent image is formed on the photoreceptor 1,
In subsequent development, a blue or yellow visible image is selectively obtained.

Next, an example in which the present invention is applied to a process using a known NP photoreceptor will be described with reference to FIGS. 2, 14, and 15.

In this process, as shown in FIG. 14, a photoconductor 1 having an insulating layer 57 on its surface is used, and as a charger, a secondary charger 30' shown by a dashed line in FIG. 2 is installed downstream of the primary charger 30. Add to. Then, a primary charger 30 applies a positive charge to the entire surface of the photoreceptor 1, and a secondary charger 30' supplies a negative charge to the entire surface. Next, as shown in FIG. 2, the composite information (Δ) in FIG. 15 obtained by the image signal processing unit 43 is
Image exposure 58 corresponding to Y)+CB) is applied to the latent image forming means 3.
1, the charge pattern on the photoreceptor 1 will be as shown in FIG. 15(B) according to the composite information. As a result,
As shown in FIG. 11, chromatic color levels B, M, C and Y, G, R of opposite polarity are separated on both sides of the achromatic color level, and the desired color is selectively developed in the same manner as described above. be able to.

Note that when using this NP photoreceptor, charge patterns other than those described above can be obtained; for example, a negative pattern in which all levels exist on one polarity side, or a charge pattern during secondary charging can be obtained. 15th by simultaneous exposure
It is also possible to form a pattern similar to that shown in the figure or a negative or positive positive or negative polarity pattern.

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. 16, 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, 39 is a fixed lens, and 47' is a movable gicchroic filter that reflects a predetermined chromatic color light and passes light of a complementary color to this chromatic color, and It is now possible to enter and exit the facility. A photosensitive layer 56 is provided on the surface of the drum-shaped photoreceptor 1, and the photoreceptor 1 rotates clockwise.

The photosensitive layer 56 is uniformly charged by the corona charger 24. The photosensitive layer 56 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 developing devices 48 and 49 containing toner of each color.
--- (However, in reality, a developing device for the desired color among G, Y, R, M, B, C, and b is arranged, but two developing devices are shown as an example in the drawing.) etc. is located.

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.

Further, around the outside of the drum 17, there is a screen charger 28 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 F. A charged particle generator (corona discharger) 19 for projecting charged particles to a position facing the photoreceptor 1 inside the photosensitive screen drum 17 is provided.

As part of the photosensitive screen 17 is shown in FIGS. 17A and 19A, the photosensitive screen 17 is a conductive screen 11 made of stainless steel or the like having a large number of fine openings 10 and having one side exposed.
, an insulating layer 13 made of nitacrylic resin or the like provided on the other side of the conductive screen, a bias conductive layer 14 made of Aβ or the like provided on this insulating layer by vapor deposition, etc., and an azo dye, selenium, etc. The photoconductive layer 15 is made of 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. 17B. Furthermore, other known layer configurations may also be employed.

FIG. 18 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 18A,
The photoconductive layer 15 is negatively charged over the entire photosensitive screen 17 by the charger 28, and then the negative charge is selectively eliminated or reduced by image exposure 32 as shown in FIG. 18B. Next, as shown in FIG. 18C, positive ion particles are applied to the photosensitive screen 1 from the charged particle source 19 described above.
7, positive ion particles pass through the negatively charged area of the screen 17 and adhere to the photosensitive layer 56 in a predetermined amount in a predetermined pattern, forming a positive electrostatic latent image. In addition,
In Fig. 18C, 1 is a bias power supply, 2 is a discharge power supply, and 3 is a DC power supply.

Next, an image forming process using the photosensitive screen 17 will be explained with reference to FIGS. 19 and 20. However, in this diagram,
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 44 . At this time, as the dichroic mirror 47/, a mirror having the function of reflecting the B component light and transmitting the G and R component lights of the light reflected from the original is used. 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 irradiated from the charged particle source 19, the positive ion particles pass through the negatively charged area of the photosensitive screen 17, reach the photosensitive layer 56, and leave a negative charge on the photosensitive layer 56. and the positive charges that have passed through the photosensitive screen 17 to form a new combined electrostatic charge image.

However, in FIG. 19, the bias of the photosensitive screen 17 is omitted from illustration, but in reality, as shown in FIG. 18C, bias 1 is applied to the photosensitive screen 17 to control the flow of the positive ion particles. ing.

That is, as shown in FIG. 20, by controlling the bias
For example, if the bias is set to a low value (1), more ion particles (passing current) will pass through the photosensitive screen. As a result, a certain amount of positive ion particles will pass through even where the screen surface potential is zero. Therefore, as shown in FIG. 19, on the photoreceptor 1, on both sides of the achromatic color levels W and b, there are chromatic color levels [G], (Y), and (R), and (M),
An electrostatic latent image is formed in which the chromatic color levels CB) and [C] are separated, but only the blue level CB) has negative fiber properties. In other words, the bias V1 increases the blue level CB)
will be selected and visualized with positive polarity toner in the next development.

Note that in this process, the photosensitive layer 56 after image exposure
Upper charge image (image information [Y]) and photosensitive screen 17
When the above charge image (image information [B]) is combined, the polarity of the image information (B) is reversed by the positive ion particles from the particle source 19, and the combined information ((Y) + (B) ).

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

For example, three or more types of image information may 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. Furthermore, the means for selecting the specific level as described above may be modified in various ways, for example by adding a constant voltage (or current) to the output voltage (or current) of the latent image forming means such as a multi-stylus, ion flow control electrode, etc. A desired color level may be selected.

6. Effects of the Invention As described above, the present invention combines a plurality of image information obtained by optical means so that the chromatic color level can be separated from the achromatic color level, and further selects a specific color level from this combined information. Therefore, it is possible to form a corresponding image with the desired colors clearly separated. 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, in which Fig. 1 is a basic process diagram during image formation, Fig. 2 is a schematic diagram of an image forming apparatus, and Fig. 3 is a schematic diagram of another developing bias method. , Figure 4 is the second
Figure 5 and Figure 6 are process diagrams for image formation using the apparatus shown in the figure, Figure 7 is a schematic diagram of another image forming apparatus, Figure 8 is Figure 7. Figure 9 is a schematic diagram of another image forming apparatus, Figure 10 is a schematic diagram of the developing bias method, and Figure 11 is a diagram of the 9th image forming apparatus.
Figure 12 is a schematic diagram of another image forming apparatus, and Figure 13 is a process diagram of image forming using the apparatus shown in the figure.
Figure 2 is a diagram of the main process when forming an image using the device, Figure 14 is a diagram of the process when forming another image, Figure 15 (A
) is a potential diagram of synthetic information, and Figure 15 (B) is the first
4 is a potential diagram explaining the process; FIG. 16 is a schematic diagram of another image forming apparatus; FIGS. 17A and 17B are enlarged sectional views of a part of the photosensitive screen;
- Figures 18A, 18B, and 18C are process diagrams of the image forming process using a photosensitive screen;
FIG. 6 is a process diagram of image formation using the apparatus, and FIG. 20 is a graph showing changes in passing current due to bias of the photosensitive screen. In addition, in the codes shown in the drawings, 1-1----photosensitive drums 13A, 13B, 13G, 48.49---~----
-Developer 17--------Photosensitive screen 19
- ・-1-Charged particle source 31.55--1-Latent image forming means 40.47
' −−−−〜−−−−−・−Dichroic mirror 4
1.42.53------- COD (charge-coupled device) 43.54-----One image signal processing section 44-----Original image or manuscript 4
6----------Suisochi 47------- Constant charge charging electrode 51.5
2--------・--Filter 56・----1----
---Photosensitive layer V 01% Vnz '-----・-----<DC) Development bias A C+, A Cz ------
---1. (AC) developing bias V+, V'+
'−'−・−・−・・−(DC) bias. Agent Patent Attorney Aisaka Hiroden Aya9 悴會Myoυ Fig. 13 8 (Additional ffA1 Fig. 14 [Y] + IBI War Haya Keyaki Priest - Shun LO (!11 Marriage Wife)

Claims (1)

[Claims] 1. Optical means for obtaining a plurality of image information from an original image; a synthesis means for synthesizing the plurality of image information such that a chromatic color level is separable from an achromatic color level; 1. An image forming apparatus comprising: selection means for selecting a specific color level from composite information. 2. Chromatic color levels are formed on both sides of the achromatic color level,
Apparatus according to claim 1. 3. The device according to claim 1 or 2, wherein the plurality of image information includes image information that is inverted to each other at least when combined. 4. The device according to any one of claims 1 to 3, wherein the selection means is a developing bias. 5. The device according to any one of claims 1 to 3, wherein the selection means is a constant charge charging means. 6. Claims 1 to 3, wherein the selection of the specific level is performed in a signal processing unit that synthesizes a plurality of image information.
A device described in any one of paragraphs.