JPS60104967A - Color copying device - Google Patents

Abstract

PURPOSE:To attain monochromatic copying by automatic switching and to improve copying speed by selecting a monochromatic copying mode when an original is decided as a linear picture. CONSTITUTION:When an original is decided as a linear picture by a sensor part 20 and a picture discriminating device 30 formed on a holder part of a light source 1, a control device 40 interlocking with the deciding output of the device 30 selects a black developing part 8B in a developing device 8. A latent image formed on a photosensitive drum 4 by exposure through a neutral filter in a color decomposing means 7 is developed by the developing part 8B. The constitution automatically switching a color copying mode to the monochromatic copying mode when the color copying is unnecessary makes it possible to execute the monochromatic copying and improve the copying speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color copying apparatus used when obtaining a color copy image, and more specifically, when the original is a gradation drawing or a line drawing (including a character drawing). By changing the copying process depending on the case, the copying speed for line drawings is improved.

(Prior Art) A conventional color copying apparatus of this type has a schematic configuration as shown in FIG. 1, for example. In Figure 1, 1 is the manuscript table 2.
- a light source for blackening the original 3; 4 is a photosensitive drum having a photosensitive layer made of selenium or a photosensitive material such as a photoconductor on its surface;
A charging electrode 5 charges the photoreceptor of the photoreceptor drum 4 by corona discharge. Reference numeral 6 indicates that the reflected light corresponding to the original image on the original platen 2 is transmitted to the photosensitive drum 4 via the color separation means 7.
It is an optical system that forms and covers a static latent image when applied to a surface.

The color separation means 7 includes a red filter R2 a green filter G
, blue filter B are selectively placed on the optical path of the optical system 6. , 8 are developing sections 8Y, 8M, 8C
Among the developing sections, the developing section 8Y visualizes the electrostatic latent (4) with yellow toner, and similarly, the developing sections 8M and 8C respectively convert the electrostatic latent (4) into a visible image. The wl image is visualized using magenta and cyan toner. A cleaning device 9 cleans toner remaining on the surface of the photosensitive drum 4 after transfer.

10 is a first paper feed roller that is stored in a paper feed cassette 11 and feeds the lζ transfer paper PR to a predetermined position; 12 is a transfer paper P;
2nd f8 paper roller that sends out R at a certain timing, 1
3 is a transfer paper holding drum that holds the transfer paper PR. Note that in this figure, the transfer electrode that transfers the toner visible image on the surface of the photoreceptor drum/1 to the transfer paper PR by corona discharge is omitted in the drawing, but the transfer electrode is used for the development RF? and cleaning device 9, near the bottom of the joint between holding drum 13 and photoreceptor drum 4.
15 is a cleaning device for cleaning the surface of the holding drum 13; 16 is fixed to the holding drum 13 and rotates to hold the transfer paper PR, which has been transferred the required number of times, to the holding drum 13; The dividing electrode 17 is separated from the transfer paper PR, and is a fixing device that fixes the toner image on the transfer paper PR.

In the conventional device configured as described above, the photosensitive drum 4
and the holding drum 13 rotate in the direction of the arrow in the figure,
The copying operation is performed as follows.

That is, after the color separation means 7 places a first filter (for example, a red filter R) on the optical path, the reflected light from the original 3 passes through the filter and is applied to the photoreceptor drum 4 as a first color. Forming an instar. The electrostatic latent image of the first color is subsequently visualized in a predetermined developing section in the developing device 8 and transferred to the transfer paper PR fixed to the holding drum 13. Even if this first toner image transfer occurs, the minute electrode 16 is not energized;
Therefore, the transfer paper PR rotates together with the holding drum 13 while being fixed to the holding drum 13 even after this transfer. on the other hand,
1.1 on the photoreceptor drum 4, and after the residual toe J- after the first transfer is removed by the cleaning device 9, the electrostatic latent image of the second color is applied in the same manner as the formation of the electrostatic latent image of the first color. A latent image is formed and visualized in a predetermined developing section within the developing device 8. This 1-toner image is then transferred onto the transfer paper PR so as to match the first transferred toner image.

For the third color, an electrostatic latent image is formed and developed in exactly the same manner, and the 1 to 3 toner images are transferred to the transfer paper PR.

The transfer paper PR after 3 transfers is 1 minute! (Den Mi
16 and is separated from the holding drum 13 and sent to a fixing device 17, where it is subjected to a fixing process. Furthermore, this 3f!
! (Yellow, Magenta, Cyan)
Since the black color of the copied image becomes cloudy and the brightness is impaired, a developing section that develops with black toner is added in the developing section 8, and an electrostatic latent image that becomes visible is formed in the developing section. In some cases, a neutral filter is set in the color separation means 7 instead of a color separation filter.

In any case, in the conventional apparatus as described above, when obtaining one copy image, an electrostatic latent image is formed three or four times→
The process of development -> transfer and separation is always carried out. For this reason, the original has only black images (C female, 1, but 22)
The problem is that the process is repeated, the copying time is very short, and the copying cost is also high. Generally, black images are often line drawings, including this black image,
When copying line drawings, there is no need to use the color copying machine 1, and it is common sense to use a monochrome copying machine.

For this reason, color copying 11ijff has heretofore been used less frequently and its usefulness has been lowered.

(Object of the Invention) The present invention has been made in view of the above circumstances, and its purpose is to provide a color copying device that also has the functions of a 1i-color copying device, and to change the switching at a certain level. ! i! l(
Based on this, it is an object of the present invention to provide a color copying apparatus that can perform automatic copying and improve the copying speed in the case of single-copying.

(Structure of the Invention) The present invention that achieves this object has a discriminating means for discriminating whether a document is a line drawing or a gradation drawing, and when the discrimination result by the discriminating means is a line drawing, a single color The feature of this invention is that it is configured so that the copy mode can be selected according to the following.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is an overall configuration diagram showing an embodiment of the present invention, and its mechanical components are the same as those of the device shown in FIG. 1, except that the developing device 8
The color separation means 7 allows a neutral filter N to be placed on the optical path, and the sensor 20 for image discrimination.
The difference is that the sensor 20 is provided in a part of the holder of the light source 1 (at any position where the document can be read). Therefore, explanations of mechanical components other than those described above will be omitted, with the same reference numerals as in FIG. 1 being used. The symbol q30 in FIG. 2 is an image discrimination unit 'aA' which discriminates whether the original is a line drawing or a gradation drawing based on the output Se of the sensor 20, and the discrimination result is inputted to the control device ii as a signal S1). has been done. The control device δ40 controls the color separation means 7, the developing device 8, the light source 1. Photosensitive drum 4, 1S drum 1
3. This is for driving various equipment such as electrodes 5, 14, 16, 7, etc. in a predetermined sequence (copying process). It is configured differently depending on the SC.

That is, the manual setting section 50 has a copy mode (automatic copy mode) in which copying is performed according to the output sh of the image discriminating device 30, and a single color (white C'l-) mode.

A selector switch is provided to select and override each copy mode (medium-color copy [-do]), which copies only with one of magenta, cyan, or black, and the normal color copy mode (color copy mode). It's in control! P
;P4O10 A predetermined sequence is executed in the copy mode specified by the changeover switch.

Note 1. An example of the electrical configuration of the image discriminating device 30 and its peripheral circuits is shown in FIG. For example, one of the image discrimination methods (principles) in the image discrimination device 30 shown here is to obtain a Wimaro histogram from a density signal obtained at a reading spot of a predetermined size, and to calculate a pattern of the density histogram. There is a method to distinguish images by paying attention to them. Here, this discrimination method will be explained as an example.

When the light beam signal C effective depth corresponds to the image density obtained when scanning the original image (area to be determined) with a small area spot (hereinafter referred to as spot on Q reading spora 1). In the case of line drawings, the series pattern is a pattern in which one or a few high density signals are scattered among most of the low density signals, and in the case of gradation drawings, it is a pattern in which high, medium or low density signals are relatively mixed. The distribution pattern is as follows. On the other hand, the time-series pattern of the image obtained when the spot area is relatively wide (g! In the case of , the high 11 degree signal decreases rapidly, but in the case of a gradation image, it does not show a very large change.

Next, what is the effect of spot size? I will specifically explain the difference between the 11 degree histograms. Figures 4 and 5 show the character image part (line drawing) and photographic image part (gradation drawing) of a certain newspaper with Q, a 1 mm square (0.01 mm + 2) spot and a 2 mm diameter (3.14 ml 112) spot, respectively. 11
11111 etc Vl! In the histogram scanned with IrA (Taki 1f0.1 is used as the density interval), the histogram indicated by the solid line is from the character image part (line drawing) to 1i
lII! i! The Hiss [Durum] indicated by is obtained from the photographic image area (gradation image). As is clear from comparing both figures, in the line drawing, the maximum peak of the histogram due to the 2+11111φ spot has a significantly lower iIr than the maximum peak of the 0.1 mm square spot! move to the side. On the other hand, in a gradation image, there is not much movement. In this situation, the sampling interval is Q, 3Il1m.

Even if the distance is changed to 0, 9 mm11, 0 men, 1, or 5 mm, there is almost no difference by /υ, so it can be seen that this is caused by the size of the spot. Although the tooth brushing section of the histogram can be arbitrarily set, the movement phenomenon of the maximum peak can be observed in the same way. It should be noted that the shift of the maximum peak position in the histogram of a line drawing in the direction of lower density depends on the size of the spot for reading the original, and J:
There is some variation in temperature, but statistically the spot size is 0.01ffll12 or more, especially 11Il.
It is noticeable at lI12 or higher.

Therefore, in this method, attention is paid to the movement of the maximum peak concentration position mentioned above, and the line drawing and l! ! ! Standard value for sorting i-style drawings (
As shown in FIG. Focusing on either side of B, draw the line drawing and ig before gradation on the side you focused on.
3 Calculate the cumulative IF+ of the slope.

Figure 6 is a bar graph showing cumulative values focusing on the high ig side, and the vertical axis is the value when the total number of image density samplings vl (total number of scanning points) when creating a histogram is set to 1. The cumulative value is shown (the solid line is a line drawing, the broken # is the first floor! IIJ
(picture not shown). As is clear from this figure, in the line drawing, the frequency peak of the histogram has shifted significantly to the low density side, so the cumulative value of the line drawing is very small.
Conversely, in the case before the gradation, the cumulative value is large because there is not much movement.

Therefore, if a threshold value for image discrimination (referred to as a second threshold value) is set between the product values of both hands in the graph, line drawings and gradations can be determined depending on whether the cumulative value is small or large with respect to the second threshold value. The previous discrimination becomes possible. Here, 0°3 is used as the second threshold value, as shown by the two-dot chain line in FIG.

Of course, focus on the low concentration side and accumulate fI! Even if the r value is used, a second threshold value for image discrimination can be determined in the same way. Therefore, the discrimination result of image fα2 is taken out as a binarized signal 1
It is also possible.

FIG. 7 shows 0 as the first threshold for various images.
．． This is a graph showing cumulative values when using 2.0.3, 0.4, and 0.6. In the figure, the solid line is a line drawing, and the broken line is an lPj adjustment drawing. From this figure, the first threshold value is 0.2 to 0 in effective concentration.
．． It can be understood that the angle should be set to about 6, preferably around 0°4. In addition, the second threshold (for "1", ri in the figure
You can see that it is necessary to install it in the line area.

Figure 3 of the previous 3i1i is for image discrimination and color copying based on the =1-distribution method, and in the figure,
20 is the aforementioned sensor that converts the incident light signal @So into an electrical image signal 3e, 31 is a sampling circuit for the image signal Se, and 32 is A that converts the analog signal from the sampling circuit 31 into a digital signal. ,/I) Converter, 33 is statistical processing of data.

MicroPro 1 that performs calculations and judgments such as conversion? Central processing unit (hereinafter referred to as CPU) such as a tree, 34 is CP
A memory (RAM) that records and stores data from the tJ 33 and supplies the recorded data to the CPU 33;
Reference numeral 5 designates a memory (ROM>) which stores other programs for the CPU 33's execution.Furthermore, a quasi-clock generator 36LL14 generates pulses that control the light reception time of the sensor 20, the sampling circuit 31 and It generates a clock signal that determines the operation timing of the A/D converter 32, a clock signal that determines the operation timing of the CPLI 33, and a clock signal that determines the timing of data sending or calling. 31-36 above
Each part forms an image discrimination device 30. Further, 41 is an information switching section in the control device 40, which inputs the aforementioned signals Sb and Sc.
is entered here.

Next, the operation of the color copying apparatus configured as shown in FIGS. 2 and 3 will be explained for each copy mode.

(1) Automatic copying mode In this case, first move the light source 1, and then move the image reading device 63.
Image reading is performed using 0, and discrimination before line drawing and gradation is performed. When performing this discrimination, it is not necessarily necessary to perform image discrimination by scanning and yanking the entire document; for example, if only half of the document is image discriminated and the result is before the gradation, a ( Output M month (for example, 3b = "l ~ ruby), and conversely, if it is a line drawing, continue scanning the rest, if the result is a line drawing, set sb to 1 ("), if it is before gradation, Set sb to 'L'.The discrimination result s obtained in this way
h is information cut 111! 41, the FII image (Sb
=")-1"), the copying process is performed using only the toner of a single color (for example, black) specified by the manual color setting section 50. This copying process requires only one step of forming, developing, and transferring an electrostatic latent image, so that rapid copying is possible. On the other hand, when the gradation image (81) = "L"),
As in the past, color copies are made using magenta and cyan toners, or toners in which black is added to these toners.

(2) Single-color copying need In this case, copies are made in the first color specified by the manual setting section 50. If the black 1-toner is designated and covered, copies identical to those produced by a black and white copying machine can be obtained.

(3) Color copy mode Color copies are made regardless of the line drawing or gradation side. That is, 1q copies are produced which are exactly the same as those produced by the conventional color copying apparatus.

Incidentally, although the above explanation was regarding an RPC copying machine,
It is clear that the present invention can also be applied to %1B printers, such as color inkjet printers and thermal transfer printers, in which a light image is photoelectrically converted and reproduced in four colors after color correction. Furthermore, there are various methods for image discrimination, and there is no need to limit the method to the above embodiment. Furthermore, by using Colorsen 4J°, it is possible to identify whether color information is added (d) even in line drawings,
This is thought to be an application that enters color mode.

<Effects of the Invention> As explained above, the present invention has the functions of a single-color copying machine even though it is a color copying machine, and the switching can be performed by using a fixed frame i (later). It is possible to provide a color copying apparatus that can perform automatic copying and improve the copying speed when copying from one color to another.

[Brief explanation of the drawing]

Fig. 1 is a geometric block diagram showing an example of a conventional device, Fig. 2 is an overall block diagram showing an embodiment of the present invention, and Fig. 3 is a diagram showing the specific electrical (growth) of Fig. 2. 4 and 5 are histograms for explaining an example of the discrimination method, FIG. 6 is an Azusa graph of the cumulative value of the slope obtained from the histogram in FIG. Cumulative li
It is a graph showing f+. 1...Light source 2...Document table ζ3...Document 4...Photoconductor drum 5.14...
Charged electrode 6...Optical system 7...Color separation means 8...
-Developing device 9...Cleaning device 11...Paper feed cassette 13...Transfer paper holding drum 16...Minute M electric 4Ii! , 17... Fixing device 20.
...Sensor 30...Image discrimination device 40...Control device α 50...Manual setting section PR...Transfer paper patent applicant Roku Konishi Photo Industry Co., Ltd. Agent Patent attorney Fuji Ijima Haruhaku 4 Figure sheep 5 figure g Al's lll1 惺 6 figure → banyu; 1 degree 04 → great effect mound degree

Claims (5)

[Claims] (1) It has a discriminating means for discriminating whether the original is a line drawing or a gradation drawing, and if the discrimination result of the discriminating means is a line drawing, it is configured so that a copying mode based on color can be selected. A color copying machine characterized by: (2) That the single color is black! 37. A color copying apparatus according to claim 1. (3) The color copying apparatus according to claim 1 or 2, characterized in that the color copying apparatus is configured so that the single-color copying mode can also be changed by manual operation. (4) The color copying apparatus according to claim 1 or 2, wherein the color copying apparatus is configured such that the single-color copying mode can be avoided by manual operation.
− (5) According to any one of claims 1 to 4, the determining means determines whether the original is not a line drawing when a part of the original includes a gradation drawing. Color copying machine as described.