JP2003263003A - Color image forming equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus capable of improving the quality of an image formed on transfer material. <P>SOLUTION: In the image forming apparatus provided with an image carrier 3 on which an electrostatic latent image is formed by an exposure device, a developing device 7 forming a toner image by developing the electrostatic latent image of the image carrier 3, a carrying device 17 carrying the transfer material 11, and a transfer roller 4 transferring the toner image to the transfer material 11 from the image carrier 3, a detection signal from a sensor 51 for detecting the color reflection density or the black-and-white reflection density of the transfer material 11 before transferring the toner image is transmitted to an exposure controller 2 which changes an exposure condition. <P>COPYRIGHT: (C)2003,JPO

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 such as a copying machine or a laser printer. By changing one or both of them, the quality of the color image formed on the transfer material is improved.

[0002]

2. Description of the Related Art A color image forming apparatus using an electrophotographic process generally uses a plurality of color toners and, in some cases, black toners to form an image using a digital method. In this case, minute dots are formed on an image carrier such as a photoconductor according to the image information of each color, and this is developed with the toner. In order to obtain a high-quality image, in addition to reducing the toner particle diameter and the laser beam diameter, a method of controlling each image forming unit by feedback of a signal from a sensor or the like has been proposed. Among these, the following are particularly related to color image formation. If the detection value of the environmental sensor exceeds a predetermined value during continuous printing of multiple sheets, a predetermined image is formed between the recording media, the formed image is read by the CCD sensor, and the registration controller and the system controller operate. A technique for correcting the registration of each photoconductor drum, that is, a registration technique for correcting the positional deviation of a color image (see Japanese Patent Laid-Open No. 7-234612). In the method using the intermediate transfer belt, a technique of forming a black toner image on one or more color toner images, measuring the color toner image density of the image, and adjusting the exposure amount for the black, that is, color In an image forming apparatus, a technique for automatically adjusting a black image exposure amount (Japanese Patent Laid-Open No. 5-2
(See Japanese Patent No. 97679). A first means for detecting the speckle pattern of the transfer material, a second speckle pattern detection means positioned downstream thereof, and a change in the state of the transfer material calculated from the detection result,
A technique for correcting the state of an image on a photoconductor, that is, a color image positional deviation correction technique (see Japanese Patent Laid-Open No. 2000-259044). A technique for faithfully reproducing a document in terms of glossiness by measuring the glossiness and selecting or changing transfer paper, fixing conditions, and color correction conditions according to the glossiness, and a color image misregistration correction technique 2000-290444).

[0003]

The above-mentioned technical method has been improved to improve the image quality.
In the case of a color image, there are the following problems in color reproduction. That is, when forming a glossy image in a color image, a fixing device is used to melt these toners on a transfer material such as paper to develop a color. To the human eye
Part of the external light passes through the molten toner layer, is reflected by the transfer material, and passes through the toner layer again, and is incident.
Therefore, the color image is affected by the color reflection density or the black and white reflection density of the transfer material. Further, recently, a halftone image is formed with a small-diameter pixel of 1200 dpi or more by an image processing method such as dithering or error diffusion. In this case, however, the toner does not fill the surface on the transfer material. Inevitably, the image is affected by the color reflection density or the black and white reflection density of the transfer material. The influence of such a transfer material on the color reflection density / black-and-white reflection density of an image often poses a problem when a full-color natural image, particularly a person is expressed. As a method of improving the above problem, there is a method of using a white toner. Specifically, by using a second toner containing one or more of opaque black / opaque white and transparent toner, a large number of intermediate gray levels are generated. You can
A technique for obtaining an output image density proportional to an input image density, that is, a technique for improving image quality by using a toner containing a mixture containing a white toner (see Japanese Patent No. 2711193), and a technique regarding the composition of a white toner (see Japanese Patent Laid-Open No. 2000-56514) ), A technique of a white toner and a manufacturing method thereof (see Japanese Patent Application Laid-Open No. 10-260554).

All of the above methods contribute to high image quality, but it is difficult to find common exposure conditions and development conditions when various papers, OHP sheets, etc. are used as transfer materials. In particular, in on-demand printing, which has been drawing attention in recent years, various papers are used to create one printed matter, and the color reflection density and the black-and-white reflection density are generally not equal, so under the same exposure and development conditions. It has been difficult to form an optimum full-color image. As described above, when forming full-color images on transfer materials with various color reflection density / black and white reflection density, optimum image forming conditions according to the color reflection density / black and white reflection density of the transfer material have been given so far. There was no. An object of the present invention is to provide optimum color image forming conditions (including full color) for a transfer material and improve the image quality of a color image formed on the transfer material.

[0005]

In order to solve the above-mentioned problems, in the invention described in claim 1, an image carrier for forming a toner image and an electrostatic latent image is formed on the image carrier. An exposing device, a developing device for forming a toner image on the electrostatic latent image on the image carrier, and a toner image directly on the transfer material from the image carrier or by using an intermediate transfer member. Indirectly,
An image forming apparatus having a transfer device for transferring and a transporting means for transporting the transfer material to a transfer portion is provided with a sensor for detecting a color reflection density or a black-and-white reflection density of the transfer material before the transfer of the toner image. The most main feature is a color image forming apparatus in which the exposure condition of the exposure device is changed according to the signal. According to a second aspect of the invention, an image carrier for forming a toner image, an exposure device for forming an electrostatic latent image on the image carrier, and a toner image on the electrostatic latent image on the image carrier. A developing device for forming a toner image, a transfer device for directly transferring a toner image from the image carrier to a transfer material, or indirectly using an intermediate transfer member, and a transfer material for transporting the transfer material to a transfer portion. In an image forming apparatus having a conveying means, a sensor for detecting a color reflection density or a black and white reflection density of a transfer material is provided before transfer of a toner image, and a developing condition of a developing device is changed according to the sensor signal. The main feature is the color image forming apparatus. According to a third aspect of the present invention, in the color image forming apparatus according to the first aspect, there are provided three or more types of toner for forming a full-color image and developing devices corresponding to the respective toner types. Exposure conditions of an exposure device for forming a toner image of each color from a color reflection density or black-and-white reflection density signal of a transfer material before transfer of a toner image and color reflection density or black-and-white reflection density information of the toner given in advance. The main feature of the color image forming apparatus is to change the. According to the invention of claim 4, claim 2
The color image forming apparatus according to claim 1, which has three or more types of toner for forming a full-color image and a developing device corresponding to each toner type, and the color reflection density of the transfer material before the toner image transfer described above. Alternatively, a color image forming apparatus that changes the developing conditions of a developing device for forming a toner image of each color based on a monochrome reflection density signal and color reflection density or monochrome reflection density information of the toner given in advance is provided. The main feature.

According to a fifth aspect of the invention, the color image forming apparatus according to the third aspect is characterized mainly in that the color image forming apparatus uses a white toner as one of the toner types. According to a sixth aspect of the invention, in the color image forming apparatus according to the fourth aspect, the main feature is a color image forming apparatus that uses a white toner as one of the toner types. According to a seventh aspect of the present invention, in the color image forming apparatus according to the third or fifth aspect, the color reflection density or the black-and-white reflection of the transfer material input from the memory and the sensor for recording the color reflection density of the toner species. The main feature of the color image forming apparatus is a color image forming apparatus having a calculation processor that performs a calculation process using a calculation formula for obtaining a required exposure condition from density information. According to an eighth aspect of the invention, in the color image forming apparatus according to the fourth or sixth aspect, the color reflection density and the black and white reflection of the transfer material inputted from the memory for recording the color reflection density of the toner type and the sensor. A main feature of the color image forming apparatus is a color image forming apparatus having a calculation processor that performs a calculation process by a calculation formula for obtaining a required developing condition from density information.
According to a ninth aspect of the present invention, in the color image forming apparatus according to the seventh aspect, the color image forming apparatus includes a unit for supplying a plurality of transfer materials, and the transfer material from at least the plurality of units merges onto the conveying path. The main feature of the image forming apparatus is a color image forming apparatus provided with a sensor for detecting the color reflection density or the black-and-white reflection density of the transfer material. According to a tenth aspect of the invention, in the color image forming apparatus according to the eighth aspect, the color image forming apparatus includes a unit for supplying a plurality of transfer materials, and at least on the conveying path after the transfer materials from the plurality of units merge.
A color image forming apparatus having a sensor for detecting the color reflection density or the black-and-white reflection density of the transfer material is a main feature. In the invention according to claim 11, an image carrier for forming a toner image, an exposure device for forming an electrostatic latent image on the image carrier, and a toner image on the electrostatic latent image on the image carrier. A developing device for forming a toner image, a transfer device for directly transferring a toner image from the image carrier to a transfer material, or indirectly using an intermediate transfer member, and a transfer material for transporting the transfer material to a transfer portion. In an image forming apparatus having a conveying means, a sensor for detecting a color reflection density or a black and white reflection density of a transfer material is provided before the transfer of a toner image, and the exposure condition of the exposure device and the development of the developing device according to the sensor signal. The main feature is a color image forming apparatus that changes the conditions.

According to a twelfth aspect of the invention, in the color image forming apparatus according to the eleventh aspect, there are provided three or more types of toner for forming a full-color image and a developing device corresponding to each toner type. An exposure device for forming a toner image of each color from the color reflection density or black-and-white reflection density signal of the transfer material before the transfer of the toner image and the color reflection density or the black-and-white reflection density information of the toner given in advance. The main feature of the color image forming apparatus is that the exposure conditions are calculated and exposed, and the developing conditions of the developing device are calculated and developed. Claim 13
According to the invention described in claim 12, in the color image forming apparatus according to claim 12, a main feature is a color image forming apparatus using a white toner as one of the toner types. Claim 1
According to a fourth aspect of the present invention, in the color image forming apparatus according to the twelfth or thirteenth aspect, the color reflection density or the black and white reflection density information of the transfer material inputted from the memory for recording the color reflection density of the toner type and the sensor Therefore, the main feature of the color image forming apparatus is a color image forming apparatus having a calculation processor that performs a calculation process using a calculation formula for obtaining the required exposure condition and development condition. According to the invention of claim 15, in the color image forming apparatus of claim 14,
A color having a unit for supplying a plurality of transfer materials, and having a sensor for detecting the color reflection density or the black-and-white reflection density of the transfer material on the conveying path after the transfer materials from at least the plurality of units have joined. The image forming apparatus is a main feature.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing an example of an electrophotographic color image forming apparatus to which the present invention is applied. The image forming unit has a photoconductor (hereinafter referred to as an image carrier) 3, and a charging roller 5, a developing device 7, and an intermediate transfer belt 8 are arranged around the image carrier 3. . The image carrier 3 is uniformly charged by being charged by the charging roller 5. The apparatus according to the present embodiment is a so-called negative / positive developing system in which the image carrier 3 is negatively charged and negatively charged toner is used. The writing device 1 irradiates the negatively charged image carrier 3 with laser light, and the charging potential changes according to the intensity of the light, and a potential distribution is formed according to the presence or absence of laser light irradiation and the amount thereof. The exposure control device 2 controls the exposure conditions such as the irradiation amount / irradiation intensity per pixel of the laser light. The writing device 1 includes a semiconductor laser 6 as a laser light source and a rotary polygon mirror (hereinafter,
And a laser beam emitted by the semiconductor laser 6 is applied to the surface of the image carrier 3 through the polygon mirror 9 and an optical system (not shown) such as a lens. There is. By driving the polygon mirror 9 to rotate at a constant speed by a driving source (motor) not shown, main scanning on the image carrier 3 can be performed. For writing data, the laser light is turned on / off by an image signal after data processing. Thereby, the exposure device is formed so as to form an electrostatic latent image on the image carrier 3.

The rotatable developing device 7 is provided with an appropriate number of developing rollers 15. Negative toner is mixed on the developing roller 15 with a magnetic carrier, and the developing roller 15 is rotationally moved so that the developing roller 15 has a negative polarity. Toner is carried onto the image carrier 3, and the electrostatic latent image on the image carrier 3 is visualized by the required electric field strength. A full-color color image forming apparatus is provided with a plurality of the developing rollers 15 and often holds at least three colors, most of which has four colors in which black is added. Development conditions such as the development bias applied to the development device 7 and the toner replenishment amount are controlled by the development control device 12 of the development device 7. The toner image formed on the image carrier 3 is transferred to the image carrier 3 and the intermediate transfer belt 8 one by one, and then the full-color toner image formed on the intermediate transfer belt 8 is transferred to the nip portion of the transfer roller 4. And is transferred to a transfer material (usually paper or OHP sheet) 11 by the transfer roller 4. The transfer roller 4 is configured to be pressed against the image carrier 3 by using a spring 24, a cam 25, and the like on a core metal. On the other hand, a paper feed tray (transfer material supply unit) 40a or 40
b, or the transfer material 11 sent from the manual feed tray (not shown) via the grip rollers 27a or 27b or the manual feed roller (not shown),
The transfer material 11 is stopped at the position of a conveying device (a pair of registration rollers) 17 for sending the transfer material 11 to the transfer portion, and is sent out to the nip portion of the transfer portion via the guide portion 10 in synchronism with the image on the intermediate transfer belt 8. The transfer roller 4 moves in the pressing direction (upward direction) by a current supplied from a power source (not shown), and the transfer material 11 is pressed against the intermediate transfer belt 8 by this movement, and the toner image on the image carrier 3 is sent out. It is transferred onto the transfer material 11 via the intermediate transfer belt 8. After that, the transfer material 11 exiting the transfer portion is sent to a fixing device 18, and the toner image transferred by the fixing device 18 is fused and fixed to form an image on the transfer material 11, and then discharged. The fixing device 18 includes a pressure roller 33 and a heat fixing roller 35. However, the present invention is not limited to the embodiment described here, and instead of indirectly transferring the toner image from the image carrier 3 onto the transfer material 11 using the intermediate transfer belt 8, for example. A method may be adopted in which the toner image is directly transferred from the image carrier 3 to the transfer material 11 by pressing the transfer roller 4 against the image carrier 3 without using the intermediate transfer belt 8. In addition, it can be widely applied including a so-called tandem type configuration system.

The embodiments of claims 1 and 3 will be described with reference to FIG. A sensor 51 for detecting a color reflection density or a black-and-white reflection density of the transfer material 11 and an LED (illuminator) 52 for illuminating the transfer material 11 are provided in the transfer path of the transfer material 11. In this embodiment, the sensor 51 is a combination of an illuminance sensor and a color filter. Based on the output from the sensor 51, the control status of the exposure control device 2 that controls the exposure condition is changed. In this embodiment, the RG from the sensor 51
Corresponding to B (red, green, black, etc.) output, the adhesion amount of CMYB (cyan, magenta, yellow, black) of toner for outputting a high-quality color image is experimentally obtained in advance. Further, the laser exposure amount that gives this adhesion amount was determined. This arithmetic expression and data are stored in the exposure control device 2 and written from the exposure control device 2 based on the input signal from the sensor 51 regarding the color reflection density / black and white reflection density for each of the transferred transfer materials 11. The exposure amount of the semiconductor laser 6 of the apparatus 1 was changed. For example, when the transfer material 11 is light red, the exposure amount is controlled so as to reduce the adhesion amount of magenta (M). In this embodiment, the exposure amount control is realized by changing the duty of the laser beam.
In the present embodiment, when light pink high-quality paper is used as the transfer material 11, as a result of changing the magenta (M) writing duty from 100% to 75%, the color reflection density / black and white reflection density of the conventional transfer material is changed. The reproducibility of human skin tones, etc. has been greatly improved compared to those without consideration.

The second and fourth embodiments will be described with reference to FIG. In this embodiment, instead of changing the exposure amount of the semiconductor laser 6 by using the exposure controller 2 in the embodiments of claims 1 and 3, the developing controller 12 is used to change the developing condition. By
The toner adhesion amount of each color is changed. In the present embodiment, the amount of adhered CMYB of toner for outputting a high-quality color image is experimentally obtained in advance corresponding to the RGB output from the sensor 51, and the developing condition for giving the amount of adhered toner is further determined. I asked for it. The arithmetic expression and the data are stored in the developing control device 12, and the developing control device 12 develops based on the input signal from the sensor 51 regarding the color reflection density and the black and white reflection density of each of the transferred transfer materials 11. The developing bias applied to the roller 15 was changed. For example, when the transfer material 11 is light red,
The developing bias is changed so as to approach the potential of the substrate of the image carrier 3 so as to reduce the amount of magenta (M) attached. In the present embodiment, when a light pink high-quality paper is used as the transfer material 11, the developing bias for magenta (M) writing is changed from -600V to -420V, and as a result, the color reflection density and the black and white reflection of the conventional transfer material are changed. The reproducibility of human skin tones, etc. was improved compared to the case where density was not taken into consideration.

The embodiments of claims 11 and 12 will be described with reference to FIG. This form example is the above claim 1.
In the third, second, and fourth embodiments, the image quality is improved by changing the exposure condition using the exposure control device 2, and the image quality is improved by changing the development condition using the development control device 12. As described above, the exposure control device 2 and the development control device 12 are individually used to improve the image. However, both of the control devices 2 and 12 are used to improve the image quality. Is.
In this embodiment, toner CMYB (cyan, magenta, yellow, black) is attached in order to output a high-quality color image corresponding to RGB (red, green, black, etc.) output from the sensor 51. The amount was experimentally determined in advance, and the laser exposure amount and the developing condition that gave this adhesion amount were also determined. This arithmetic expression and data are stored in the exposure control device 2 and the development control device 12, and the exposure is performed based on the input signal from the sensor 51 regarding the color reflection density / black and white reflection density of each transfer material 11 conveyed. Control device 2 to writing device 1
The exposure amount of the semiconductor laser 6 was changed and the developing bias applied from the developing controller 12 to the developing roller 15 was changed. For example, when the transfer material 11 is light red, the exposure amount is controlled so as to reduce the amount of magenta (M) adhered, and the developing bias is changed so as to approach the potential of the substrate of the image carrier 3. In the present embodiment, when light pink high-quality paper is used as the transfer material 11, the duty of magenta (M) writing is changed from 100% to 75%, and the development bias of magenta (M) writing is -600V. As a result of changing from −420V to −420V, reproducibility of human skin color and the like is greatly improved as compared with the conventional transfer material in which the color reflection density and the black-and-white reflection density are not taken into consideration.

Also in the third and fourth embodiments, when the transfer material 11 is colored, it is not possible to form an image close to pure white. Further, in the past, in order to form a high-quality image, a white material was used as the transfer material 11, and when there was a color background, the image was formed on the entire surface by color toner. However, in this case, not only the toner consumption becomes large, but also the toner adhering to the transfer material 11 easily causes curling, and the transfer material 11 on which an image is formed is thickened by the toner layer, It was not always comfortable for users. It was found that when the white toner is used, the transfer material 11 can be freely selected, a toner image can be formed only in a necessary portion, and a high-quality image can be formed.

The embodiments of claims 5, 6 and 13 will be described with reference to FIG. FIG. 2 is a schematic view showing another example of the mode of the present invention. CM as the developing roller 15
In addition to YB, a white (W) developing roller 15A is provided, and in accordance with the presence thereof, the writing device 1, the exposure control device 2, and the development control device 12 also add control for forming a white toner image. . As white toner,
A toner containing TiO ₂ as a main component in a styrene-acrylic resin was used. With this configuration,
Even when a light pink high-quality paper was used as the transfer material 11, it was possible to reproduce the skin color of a person and to make the character region white to make the character image clearer. Claim 7
Examples of modes 8 and 14 will be described with reference to FIG. FIG. 3 is a block diagram showing still another example of the mode of the present invention. RGB information of the transfer material from the sensor 51, RGB information about the toner stored in advance in the memory of the calculation processor 102, and an arithmetic expression for calculating control information for the exposure control device 2 and the development control device 12 from these information. It comprises a creation unit 101 and a calculation processor 102 that calculates an arithmetic expression based on this expression and the above information. The output signal of the calculation processor 102 may be sent to the exposure control device 2 to change the exposure condition as the control information of each color in the exposure control device 2, or the output signal of the calculation processor 102 may be sent to the development control device 12. The developing condition may be changed as the control information of each color in the developing control device 12, or both the exposing condition and the developing condition may be changed instead of being changed independently. The color reflection density / black and white reflection density information regarding the toner may be set by previously measured data, or may be measured by disposing a sensor in the toner hopper or the like. In the latter case, although the cost of the sensor and the like increases, changes in the color reflection density / black and white reflection density of the toner due to the lot or changes over time can be dynamically reflected in the control conditions.
In this case, since the exposure condition and the development condition can be calculated by the calculation processor 102 according to the input information, the exposure control device 2 and the development control device 12 may omit the function of calculating the exposure condition and the development condition for the input information. it can. In FIG. 3, only the part related to the process of the transfer material 11 from the sensor 51 is extracted and described.
In an actual machine, the calculation processor 102 may also perform various process control and image processing. For this reason, by separately configuring the calculation processor 102 and the arithmetic expression creation unit 101, it is possible to flexibly change the arithmetic expression and the calculation processor 1
02 can be used efficiently. Further, the calculation formula creation unit may be provided in the calculation processor 102 to create the calculation formula.

Embodiments of claims 9, 10 and 15 will be described with reference to the drawings. Many printers, copiers, plain paper faxes, etc. can supply a plurality of types of transfer materials. For this reason, it is costly to dispose a sensor for measuring the color reflection density / black and white reflection density for each transfer material. Therefore, it is possible to reduce the cost by disposing the sensor on the conveyance path after the transfer materials from the plurality of transfer material supply units merge. Two transfer material supply units 40a and 40b shown in FIG.
On the other hand, the sensor 51 is arranged on the path (downstream) after the transfer materials 11 supplied from the transfer material supply units 40a and 40b merge. Although not shown in this figure, further, in the case of an apparatus having a manual paper feeding unit, it is preferable to arrange it in a path (downstream) after the transfer materials from the manual paper feeding unit merge. However, the sensor 51 is provided downstream of the conveyance path of the transfer material 11.
When arranging, it is necessary to pay attention to two points. One is that the calculation processor 102 calculates based on the output from the sensor 51, and the time until the exposure control device 2 and the development control device 12 are controlled based on the calculation is shortened. This requires optimizing the arithmetic algorithm and using a high-speed processor. Secondly, even if the image forming condition is changed based on the signal from the sensor 51, there is a mechanical constraint condition so that it is reflected. In FIG. 1, since the intermediate transfer belt 8 exists, the image forming change may not be reflected after the transfer materials from the manual paper feeding unit merge. The installation position needs to be set at an optimum position in consideration of these two conditions. It should be noted that the present invention is not limited to the above-described embodiment, but the calculation processor 102 may be provided in the exposure control device 2 and the development control device 1.
The calculation function may be omitted from the exposure control device 2 and the development control device 12 so as to have a function of creating an arithmetic expression which is a basis of the control instruction signal to 2, and the calculation processor may be simplified. The exposure control device 2 and the development control device 12 are provided with a control function for sending output signals directly from the semiconductor laser 6 and the development device 7 to the control device 102.
Needless to say, various modifications can be made without departing from the scope of the present invention.

[0016]

According to the color image forming apparatus of the present invention described above, various excellent effects as described below can be obtained. (I) According to the first aspect of the present invention, the exposure condition of the exposure device is changed according to the output from the sensor that detects the color reflection density or the black and white reflection density of the transfer material. Sometimes high image quality can be obtained. (II) According to the second aspect of the present invention, since the developing condition of the developing device is changed according to the output from the sensor that detects the color reflection density or the black and white reflection density of the transfer material, the color image reproduction is performed. Sometimes high image quality can be obtained. (III) According to the invention described in claim 3 of the present invention, in addition to the constitutional requirements of the invention described in claim 1, toners of three or more colors for forming a full-color image are given in advance. Since there is an exposure control device that controls the exposure amount by calculating the exposure condition for forming the toner image of each color from the color reflection density information or the black and white reflection density information of the toner, higher image quality can be obtained. (IV) According to the invention described in claim 4 of the present invention, in addition to the constitutional requirements of the invention described in claim 2, toners of three or more colors for forming a full-color image are given in advance. Since the development control device for controlling the developing bias by calculating the developing condition for forming the toner image of each color from the color reflection density or the black and white reflection density information of the toner, higher image quality can be obtained. (V) According to the invention of claim 5 of the present invention, in the invention of claim 3, since a white toner is used as one of the toner types, a high image quality can be obtained. (VI) According to the invention described in claim 6 of the present invention, in the invention described in claim 4, since a white toner is used as one of the toner types, a high image quality can be obtained.

(VII) According to a seventh aspect of the present invention, in the invention according to the third or fifth aspect, the transfer inputted from the memory for recording the color reflection density of the toner species and the sensor. Since it has a calculation processor that performs a calculation process by a calculation formula for obtaining the required exposure condition from the color reflection density or the black and white reflection density information of the material, the calculation processor for controlling the exposure apparatus is a processor related to process control / image processing. It becomes possible to share the same with the above, and the cost can be reduced, and the exposure conditions can be changed very easily. (VIII) According to the invention of claim 8 of the present invention, in the invention of claim 4 or 6, the color of the transfer material input from the memory for recording the color reflection density of the toner species and the sensor. Since there is a calculation processor that performs calculation processing by a calculation formula that obtains the required development conditions from the reflection density or black and white reflection density information, the calculation processor for controlling the developing device
Since it can be shared with a processor related to image processing, the cost can be reduced and the development conditions can be changed very easily. (IX) According to the invention of claim 9 of the present invention, in the invention of claim 7, the color reflection density or the black-and-white reflection density of the transfer material is detected on the conveying path after the transfer materials merge. Since the sensor that operates is provided, the cost can be reduced. (X) According to the invention of claim 10 of the present invention, in the invention of claim 8, the color reflection density or the black-and-white reflection density of the transfer material is detected on the conveying path after the transfer materials merge. Since the sensor that operates is provided, the cost can be reduced. (XI) According to the invention of claim 11, the exposure condition of the exposure device and the development condition of the developing device are changed according to the output from the sensor that detects the color reflection density or the black-and-white reflection density of the transfer material. Therefore, it is possible to obtain higher image quality when reproducing a color image. (XII) According to the invention of claim 12 of the present invention, in addition to the constituent features of the invention of claim 11, three or more types of toner for forming a full-color image and respective toner types In order to form a toner image of each color from three or more color toners for forming a full-color image based on the color reflection density or the black-and-white reflection density information of the toner given in advance, The exposure condition is calculated to control the exposure control device, and the development condition is calculated to control the development control device, so that higher image quality can be obtained. (XIII) According to the invention of claim 13 of the present invention, in the invention of claim 12, since a white toner is used as one of the toner species, a high image quality can be obtained. (XIV) According to the invention of claim 14 of the present invention, in the invention of claim 12 or 13, the transfer material inputted from the memory for recording the color reflection density of the toner species and the sensor is recorded. Since it has a calculation processor that performs arithmetic processing according to an arithmetic expression for obtaining the required exposure condition from the color reflection density or the black and white reflection density information, the processor for controlling the exposure apparatus and the development apparatus is used for process control and image processing. Since it can be shared with the related processor, the cost can be reduced and the exposure condition and the development condition can be changed very easily. (XV) According to the invention of claim 15, in the invention of claim 14, the color reflection density or the black-and-white reflection density of the transfer material is detected on the conveying path after the transfer materials merge. Since the sensor that operates is provided, the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of one embodiment of the present invention.

FIG. 2 is a schematic view showing another embodiment of the present invention.

FIG. 3 is a block diagram showing still another embodiment of the present invention.

[Explanation of symbols]

1 writing device 2 Exposure control device 3 photoconductor (image carrier) 4 Transfer roller 5 charging roller 6 Semiconductor laser 7 Developing device 8 Intermediate transfer belt 11 Transfer material (paper, OHP sheet) 12 Development control device 15, 15A developing roller 17 Conveyor (register roller pair) 18 Fixing device 40a, 40b Paper feed tray (transfer material supply unit) 51 sensor 101 Arithmetic Formula Creation Unit 102 Computational processor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/00 303 G03G 15/00 303 15/04 15/08 503A 15/043 15/16 15/08 503 15/04 120 15/16 F term (reference) 2H027 DA32 DC01 DC03 DE02 DE07 DE09 EB04 EC06 EC18 EC20 ED06 ED09 ED16 EE01 EE07 EF09 FA28 FA30 ZA07 2H030 AA02 AD05 AD13 AD17 BB02 BB15 AB24 BB34 BB42 2H07 DA75 AB AB EA01 2H077 AD06 AD35 DA01 DA49 DA63 DA82 DB08 DB13 EA03 GA13 2H200 FA18 GA09 GA10 GA14 GA34 GA45 GA47 GA56 GA59 GB22 GB25 HA02 HA28 HB12 HB22 JA02 JC03 MC20 PA03 PA09 PA19 PA22 PB01

Claims (15)

[Claims] 1. An image carrier for forming a toner image,
An exposure device that forms an electrostatic latent image on the image carrier, a developing device that forms a toner image on the electrostatic latent image on the image carrier, and a toner image on the transfer material from the image carrier. In the image forming apparatus having a transfer device for directly or indirectly using an intermediate transfer member, and a conveying unit for transporting the transfer material to the transfer portion. A color image forming apparatus comprising a sensor for detecting a color reflection density or a black-and-white reflection density of a material, and changing an exposure condition of an exposure device according to the sensor signal. 2. An image carrier for forming a toner image,
An exposure device that forms an electrostatic latent image on the image carrier, a developing device that forms a toner image on the electrostatic latent image on the image carrier, and a toner image on the transfer material from the image carrier. In a image forming apparatus having a transfer device for directly or indirectly using an intermediate transfer member, and a conveying unit for transporting the transfer material to the transfer portion, the transfer material is transferred before the transfer portion of the toner image. A color image forming apparatus comprising a sensor for detecting the color reflection density or the black-and-white reflection density, and changing the developing condition of the developing device according to the sensor signal. 3. The color image forming apparatus according to claim 1, further comprising three or more types of toner for forming a full color image and a developing device corresponding to each toner type, From the color reflection density or black and white reflection density signal of the transfer material and the color reflection density or black and white reflection density information of the toner given in advance,
A color image forming apparatus, wherein an exposure condition of an exposure device for forming a toner image of each color is changed. 4. The color image forming apparatus according to claim 2, further comprising three or more types of toner for forming a full-color image and a developing device corresponding to each toner type, From the color reflection density or black and white reflection density signal of the transfer material and the color reflection density or black and white reflection density information of the toner given in advance,
A color image forming apparatus, wherein a developing condition of a developing device for forming a toner image of each color is changed. 5. The color image forming apparatus according to claim 3, wherein a white toner is used as one of the toner types. 6. The color image forming apparatus according to claim 4, wherein a white toner is used as one of the toner types. 7. The color image forming apparatus according to claim 3, wherein the memory for recording the color reflection density of the toner type and the color reflection density or black and white reflection density information of the transfer material input from the sensor are used. A color image forming apparatus having a calculation processor for performing a calculation process according to a calculation formula for obtaining a required exposure condition. 8. The color image forming apparatus according to claim 4 or 6, comprising: a memory for recording the color reflection density of the toner type; and color reflection density and black-and-white reflection density information of the transfer material input from the sensor. A color image forming apparatus having a calculation processor for performing a calculation process according to a calculation formula for obtaining required developing conditions. 9. The color image forming apparatus according to claim 7, further comprising a unit for supplying a plurality of transfer materials, wherein the transfer materials of at least the plurality of units are provided on the conveying path after the transfer materials merge. A color image forming apparatus comprising a sensor for detecting color reflection density or black-and-white reflection density. 10. The color image forming apparatus according to claim 8, further comprising a unit that supplies a plurality of transfer materials, and the transfer materials of the transfer materials are provided on a conveyance path after the transfer materials from at least the plurality of units merge. A color image forming apparatus comprising a sensor for detecting color reflection density or black-and-white reflection density. 11. An image carrier for forming a toner image, an exposure device for forming an electrostatic latent image on the image carrier, and a toner image for the electrostatic latent image on the image carrier. A developing device, a transfer device for directly transferring the toner image from the image carrier to the transfer material or indirectly by using an intermediate transfer member, and a conveying means for transporting the transfer material to the transfer portion. In the image forming apparatus having the above, a sensor for detecting the color reflection density or the black and white reflection density of the transfer material is provided before the toner image transfer portion, and the exposure condition of the exposure device and the development condition of the developing device are set according to the sensor signal. The color image forming apparatus is characterized in that 12. The color image forming apparatus according to claim 11, further comprising three or more types of toner for forming a full-color image and a developing device corresponding to each toner type, wherein the toner image transfer is performed. The exposure condition of the exposure device for forming the toner image of each color is calculated from the color reflection density or black and white reflection density signal of the previous transfer material and the color reflection density or black and white reflection density information of the toner given in advance. A color image forming apparatus is characterized in that it is exposed, and the developing conditions of the developing device are calculated to develop. 13. The color image forming apparatus according to claim 12, wherein a white toner is used as one of the toner types. 14. The color image forming apparatus according to claim 12, wherein the memory for recording the color reflection density of the toner type and the color reflection density or black-and-white reflection density information of the transfer material input from the sensor are used. ,
A color image forming apparatus having a calculation processor for performing arithmetic processing according to arithmetic expressions for obtaining required exposure conditions and developing conditions. 15. The color image forming apparatus according to claim 14, further comprising a unit that supplies a plurality of transfer materials, and the transfer materials of the transfer materials are provided on a conveying path after the transfer materials from at least the plurality of units merge. A color image forming apparatus comprising a sensor for detecting color reflection density or black-and-white reflection density.