JP3081263B2 - Color image forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic color image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, as a color image forming apparatus, an electrophotographic type is well known. FIG. 4 shows the structure of such a conventional color image forming apparatus.

In FIG. 4, reference numeral 9 denotes an illumination lamp, and 10 denotes a light receiving element. The illumination lamp 9 and the light receiving element 10 read the original 11 while scanning, and convert the original into three-color electric signals of R, G, and B. I do. The three-color signals are converted into four-color signals of magenta, cyan, yellow, and black by an image processing device (not shown).
Is irradiated. The surface of the photoreceptor on the photosensitive drum 1 is preliminarily cleaned by the cleaner 5 before the irradiation is performed, and after the influence of the previously formed latent image is removed by the pre-exposure lamp 12 and the pre-discharger 13, the primary The charger 6 is uniformly charged. Then, light corresponding to a magenta image signal is first radiated to the photosensitive drum 1 from a light source 2 such as a laser to form a magenta latent image. This latent image is developed by the magenta developing device 3M, and a magenta image is formed on the photosensitive drum 1.

On the other hand, the transfer material 14 stored in a cassette
Is transferred to the transfer drum 4 and electrostatically attracted onto the transfer drum 4 by the attraction charger 16. Then, the transfer material 14
Is transferred to the opposing portion of the photosensitive drum 1 and the transfer charger 7 by the rotation of the transfer drum 4, and the magenta toner image on the photosensitive drum 1 is transferred onto the transfer material 14 by the transfer charger 7.

Subsequently, toner images of cyan, yellow, and black are sequentially formed on the photosensitive drum 1 in the same manner, and then transferred onto the same transfer material 14 to form a full-color image. At this time, each of the developing devices 3C, 3Y, and 3BK slides in the horizontal direction to perform development at a position facing the photosensitive drum 1.

After the transfer of all colors is completed in this way, the transfer material 14 is separated from the transfer drum 4 by the separation claws 17 and sent to the fixing device through the conveyor belt 18.
After the image is fixed in the fixing device,
The transfer material 14 is discharged to a discharge tray 19.

As a color developer used in such an image forming process, a two-component developer in which a non-magnetic toner and a magnetic carrier are mixed is generally used. This is because it is difficult to produce a beautiful color toner in a magnetic toner because the magnetic material is black. For this reason, a device using a magnetic toner only as a black toner has been proposed.

[0008]

However, according to the above-mentioned prior art, since the melting temperature of the magnetic toner is different from that of the toner containing no magnetic material, the fixing condition is determined by the ratio of the magnetic toner to the non-magnetic toner on the image. It is necessary to set according to. For example, if a large amount of black toner is contained, sufficient fixing performance cannot be obtained unless the fixing temperature is set high.If a small amount of black toner is contained, the fixing temperature is increased unnecessarily. Otherwise, the life of the fixing roller will be shortened. For this reason, it has been necessary to set sufficient fixing conditions and to set the fixing conditions so as to minimize the influence on the roller life.

On the other hand, the ratio between the black toner and the color toner in a digital color image greatly changes depending on image processing.

In the prior art, even if the ratio between the black toner and the other color toner changes due to various factors, the fixing conditions cannot be optimized each time, and the fixability becomes insufficient or unsatisfactory. There is a problem that the life of the roller is shortened due to the necessary high fixing temperature.

[0011] The present invention solves the above-mentioned problems, and does not adversely affect the life of the fixing roller even when a color developer containing a black developer whose melting temperature is different from that of another color is used. It is possible to provide a color image forming apparatus that can perform favorable fixing according to the ratio of the developer.

[0012]

According to the present invention, the object is to provide a reading means for reading an original, a color processing unit for converting image data received from the reading means into a predetermined color signal, A driving unit for driving the light emitting unit based on the color signal received from the unit, and developing the latent image formed by the light emitting unit into a black color having a melting temperature higher than that of the other color developer.
A color image forming unit that develops an unfixed image on a recording material by developing with a color developer containing a developer, and a fixing device that applies a predetermined heat and pressure to the unfixed image on the recording material to fix the image.
A color image forming apparatus having a control means for increasing / decreasing heat per predetermined time or pressure per predetermined area provided by the fixing device, and counting a predetermined color signal transferred from the color processing unit to the driving means. A color signal transferred from the color processing unit to the driving unit.
The present black and other colors color signals of the item, said control means,
When it is determined that the ratio of the black color signal counted by the counting means is higher than the color signal of the other color, the heat per predetermined time or the pressure per predetermined area is increased, and the ratio is different from that of the other color. It is achieved by setting to reduce heat per predetermined time or pressure per predetermined area when it is determined that the color signal is small, and
Reading means for reading an original, a color processing unit for converting image data received from the reading means into a predetermined color signal, and driving a light emitting means based on the color signal received from the color processing unit
Driving means for the latent image formed by the light emitting means
Includes black developer whose melting temperature is lower than other color developers <br/> Developed with color developer to form unfixed image on recording material
Color image forming unit and, in mosquito <br/> color image forming apparatus having a fixing device for performing fixing by applying a predetermined heat and pressure to the unfixed image on the recording material, a predetermined given above fixing device time to to increase or decrease the heat or pressure per predetermined area per
A control means, and a counting means for counting a predetermined color signal is passed to the drive means from the color processing unit that, the
The color signal passed from the color processing unit to the driving unit is black.
There are color and other colors color signals, said control means may comprise heat per a predetermined time when the ratio of the color signals of black counted by the counting means is judged to be large with respect to the other color signal Alternatively, it is set so that the pressure per predetermined area is reduced, and the heat per predetermined time or the pressure per predetermined area is increased when it is determined that the ratio is smaller than the color signal of another color. Is also achieved by

[0013]

According to the present invention, when the melting temperature of the black developer is higher than that of the other color developer, if the ratio of the black color signal is determined to be large by the signal from the counting means,
The fixing is performed by increasing the heat or pressure applied by the fixing device. Therefore, the unfixed image developed by the black developer having a high melting temperature is reliably fixed. Also,
When it is determined from the signal from the counting means that the ratio of the black color signal is small, the heat or pressure is reduced to fix the color signal. Therefore, the life of the fixing roller is not adversely affected.

On the other hand, when the melting temperature of the black developer is lower than that of the other color developer, if it is determined from the signal from the counting means that the ratio of the black color signal is large, the heat or pressure is reduced. And fix it. Therefore,
There is no adverse effect on the life of the fixing roller. Also,
When it is determined from the signal from the counting means that the ratio of the black color signal is small, the heat or pressure is increased to fix the color signal. Therefore, the unfixed image developed by the developer of another color is surely fixed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First to third embodiments of the present invention will be described with reference to the drawings.

<First Embodiment> First, a first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a block diagram of an apparatus according to a first embodiment of the present invention. The same reference numerals are given to the same parts as those in the conventional apparatus shown in FIG.

In the apparatus shown in FIG. 1, a reading element 31 such as a CCD is used.
The color original read by is divided into three-color electrical signals of R, G, and B and input to the color processing unit 32. The color processing unit 3
In step 2, the R, G, and B signals are first subjected to logarithmic conversion to convert the signals into three-color signals of cyan, magenta, and yellow.

Assuming that the three-color signals after logarithmic conversion are C, M, and Y, the black signal BK is extracted as follows.

BK = k0 min (C, M, Y) (k0 is a constant) Next, an appropriate amount of the BK component is subtracted from C, M, and Y, so-called UCR (UnderColor Removal, undercolor removal) is performed.

C '= C-k1 Bk M' = M-k2 Bk Y '= Y-k3 Bk (k1, k2 and k3 are constants) Subsequently, so-called masking is performed for color correction.

C ″ = a11 C ′ + a12 M ′ + a13 Y ′ M ″ = a21 C ′ + a22 M ′ + a23 Y ′ Y ″ = a31 C ′ + a32 M ′ + a33 Y ′ (a11 to a33 are constants) In order to finely adjust the color balance, the following γ adjustment is performed.

C ′ ″ = γ1 × C ″ M ″ ′ = γ2 × M ″ Y ″ ′ = γ3 × Y ″ Bk ′ = γ0 × Bk (γ0 to γ3 are constants). In response, the laser driving circuit 33 is driven to emit the laser light 2 to form a color image by the electrophotographic process described in the conventional example.

The toner used in this embodiment is as follows.

Black toner: main binder resin 1
A negatively charged toner having an average particle diameter of 8 μm, in which 60 parts by weight of magnetite and 3 parts by weight of a charge control agent are internally added to 00 parts by weight, and 0.6% of an external additive is externally added.

Magenta, cyan, and yellow toners: 100 parts by weight of the main binder resin and 4 parts of each pigment
A negatively charged toner having an average particle diameter of 8 μm, in which about 5 parts by weight and 4 parts by weight of a charge control agent are internally added and 0.7% of an external additive is externally added.

In the developing method, black is a non-contact developing method using a magnetic one-component toner, and cyan, magenta and yellow are a contact developing method using a two-component developer.

Further, due to the difference in toner composition, the proper fixing temperature is different between the black toner and the other three color toners, and 180 ° C. for the black toner and 180 ° C. for the other three color toners. Thus, 150 ° C. is a proper fixing temperature.

In FIG. 1, reference numeral 36 denotes a counter serving as a counting means, which has a function of counting the signals input to the laser drive circuit for each document image. The counting is performed separately for the black component count and the other component count, and the respective count values are sent to the fixing temperature control unit 34.

The fixing temperature control section 34 is provided with a CPU, which calculates the ratio between the black component and the other color components, and sets an optimum fixing temperature according to the result. In this embodiment, when the ratio of the black component is 0, the fixing temperature is set to 150.
° C, and the temperature is increased as the ratio increases. When the black component reaches 100%, the fixing temperature is set to 180 ° C.

A temperature sensor 20 is attached to the fixing roller 8, and controls the heater driving circuits 35 and 50 in accordance with the detected temperature to turn on the heaters 21 and 22.
It turns off and controls the fixing roller 8 to the set temperature.

By performing such control, even if the mode is changed and the ratio of the black toner is changed, sufficient fixability is always obtained, and the service life of the fixing roller 8 is not shortened. There is.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the fixing time is controlled according to the ratio of the black signal.

FIG. 2 is a block diagram of the present embodiment, in which the same reference numerals are given to the same parts as in the first embodiment, and the description will be omitted.

Reference numeral 37 denotes a fixing speed control unit for controlling the speed of the fixing roller 8 and the paper conveying system in front of the fixing roller 8, and controls the motors 38 and 39 in accordance with the ratio of the black signal to control the speed.

When the black ratio is 0, the speed is set to 1
The speed is reduced as the ratio increases, and 90 mm / sec when the black ratio is 100%.
Therefore, the higher the ratio of the black toner, the longer the fixing time, so that sufficient fixing property can be obtained.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the amount of pressure applied to the fixing roller is controlled according to the ratio of black.

FIG. 3 is a block diagram of the present embodiment, and the same reference numerals are given to the common parts with the first embodiment, and the description will be omitted.

The fixing pressure control unit 40 switches the spring of the fixing roller pressing unit 41 according to the ratio of the black component, and changes the amount of pressing.

The amount of pressurization when the black component is 0 is 50 kg
The amount of pressurization is increased as the amount of the black component increases, and is increased to 70 kg when the amount of the black component is 100%. By doing so, sufficient fixability can be obtained even when the ratio of the black toner is large, and a reduction in the life of the roller can be minimized.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described. Although the first to third embodiments have described the case where the melting temperature of the black toner is higher than that of the other toners, the present embodiment is the case where the melting temperature of the black toner is lower than the other toners. This is the case, for example, when it is desired to give gloss to a black object in an image and emphasize that portion.

The block diagram of this embodiment is the same as that of FIG. 1 and will not be described.

In this embodiment, the black toner does not contain a magnetic substance and has the same composition as other toners.
° C is the optimum fixing temperature for black.

In this embodiment, the fixing temperature is set to 150 ° C. when the black ratio is 0, and the temperature is lowered as the ratio increases, and set to 140 ° C. when the black ratio is 100%.

By performing such control, the same effect as in the above-described embodiment can be obtained.

In the above embodiment, the fixing conditions are controlled in accordance with the ratio of black. However, the present invention is not limited to the ratio, and only the amount of one of the black component and the color component is controlled. May be controlled by focusing on
Further, black may be controlled in accordance with a function value with another color component.

[0047]

As described above, black and other colors exist.
According to the present invention, according to the present invention, the ratio of the color signal to the other color of black determined by the signal from the counting means is used to increase or decrease the heat or pressure given by the fixing device. Good fixing can be performed without adversely affecting the life of the toner.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of an apparatus according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a schematic configuration of an apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic view of a conventional color electrophotographic apparatus.

[Explanation of symbols]

 31 reading unit (reading element) 32 color processing unit 34 control unit (fixing temperature control unit) 36 counting unit (counter)

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 13/01 G03G 13/20 G03G 15/00 303 G03G 15/01 G03G 15/20 G03G 21/00 370- 502

Claims (2)

(57) [Claims] And 1. A reading an original reading means, for driving a color processing unit for converting the image data received from said read means to a predetermined color signal, the light emission means based on the color signals received from the color processing unit The driving unit and the latent image formed by the light emitting unit are melted at a temperature higher than that of the developer of another color in black.
Performed in a color image forming section for forming an unfixed image is developed on <br/> recording material by a color developer containing a developing agent, a fixing giving a predetermined heat and pressure to the unfixed image on the recording material In a color image forming apparatus having a fixing device, a control means for increasing or decreasing heat per predetermined time or pressure per predetermined area given by the fixing device, and a predetermined color transferred from the color processing unit to the driving means. Counting means for counting a signal, which is passed from the color processing unit to the driving means.
That the color signal exists black and other colors color signal, the control means, when a ratio of color signals of black counted by the counting means is judged to be large with respect to the other color signal The heat per predetermined time or the pressure per predetermined area may be increased, and the heat per predetermined time or the pressure per predetermined area may be reduced when the ratio is determined to be smaller than the color signal of another color. A color image forming apparatus characterized by being set. 2. A reading an original reading means, for driving a color processing unit for converting the image data received from said read means to a predetermined color signal, the light emission means based on the color signals received from the color processing unit The driving unit and the latent image formed by the light emitting unit are melted at a melting temperature lower than that of the developer of another color.
Performed in a color image forming section for forming an unfixed image is developed on <br/> recording material by a color developer containing a developing agent, a fixing giving a predetermined heat and pressure to the unfixed image on the recording material In a color image forming apparatus having a fixing device, a control means for increasing or decreasing heat per predetermined time or pressure per predetermined area given by the fixing device, and a predetermined color transferred from the color processing unit to the driving means. Counting means for counting a signal, which is passed from the color processing unit to the driving means.
That the color signal exists black and other colors color signal, the control means, when a ratio of color signals of black counted by the counting means is judged to be large with respect to the other color signal The heat per predetermined time or the pressure per predetermined area may be reduced, and the heat per predetermined time or the pressure per predetermined area may be increased when it is determined that the ratio is smaller than the color signal of another color. A color image forming apparatus characterized by being set.