JP2001092212A - Image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image forming device that maintains the better color image quality, even when optimizing control of the color developer adhesion quantity control by means of adjusting development bias voltage is difficult, owing to unsatisfactory developing function of respective developing device by minimizing the change of color tone on the final color printing image, regardless of the array order of the respective developing device. SOLUTION: This color image forming device 1 is provided with color information detecting means 4a to 4d, detecting the array order of developing devices 5 stored in guiding members 6, for performing the output printing in an appropriate color tone, even if storing array order of the image forming part F1 to F4 is respectively in any array order, and the developing bias driving device 10 changing/controlling unit developer quantity for developing by the respective developing device 5, based on the array order of developing devices 5 being the detection result of the color information detection means 4a to 4d, to the developer quantity, based on predetermined developer quantity for each developing device 5 or the developer quantity based on preregulated rule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for performing multicolor printing by applying an electrophotographic method.

[0002]

2. Description of the Related Art Conventionally, in a color image forming apparatus,
Each color image developing device for storing the toner of each color is provided in series in the paper transport direction, and the corresponding color image is superimposed and formed on the same paper surface by each color image developing device as the paper is transported. After passing through the color image developing device, the sheet on which the toner image is superimposed is passed through a heating heat roller of the fixing device, so that toner is welded to the sheet by the heat of the roller surface to form an image.

[0003]

However, the order of inserting and arranging the respective color image developing devices into the main body determines the order of the superposition transfer, and the color developing device arranged at the most downstream in the superposition transfer step. The color toner of the device adheres to the outermost surface of the transfer paper, and is most susceptible to heat on the surface of the heat roller of the fixing device. As a result, there is a problem that a change in the order in which the developing devices are inserted, that is, the order in which the color toners are superposed, causes a change in the color tone of the color print image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is intended to minimize the change in color tone of a final color print image regardless of the order in which the color developing devices are inserted. An object is to provide a developing device. It is also an object of the present invention to provide a color image developing device that maintains better color image quality even when the developing function of each color developing device is insufficient and it is difficult to control the amount of color toner adhesion by adjusting the developing bias voltage. Also aim.

[0005]

The present invention has the following configuration to achieve the above object. The configuration of the first aspect of the present invention includes an electrostatic latent image carrier, an exposure unit that forms an electrostatic latent image on the electrostatic latent image carrier, and a developing device that internally holds the formed electrostatic latent image. A plurality of image forming units each including a developing unit that visualizes the image with a developer are arranged in accordance with each color, and a plurality of developing units in each of the image forming units are detachably provided to the apparatus main body. Store the developing unit in any storage area
An image forming apparatus having a developing unit storage unit that can be arranged, wherein a developing unit arrangement detecting unit that detects an arrangement order of the developing units stored in the storage unit, and a developing unit arrangement order that is a detection result of the developing unit detecting unit. Developing amount control means for controlling the amount of the developer to be developed by each of the developing devices based on the amount of the developing device to a predetermined amount of the developing device or a developing amount based on a predetermined rule. An image forming apparatus comprising:

A second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the developing amount control means is a developing bias control device for controlling a developing bias voltage of each developing device. .

A third feature of the present invention is to provide a fixing device for fixing a developer image formed on a transfer material to the transfer material by heating, and the developing device is detected by the developing device arrangement detecting means. The image forming apparatus according to Summary 1 or 2, wherein the fixing temperature of the fixing device is changed and controlled based on the arrangement order.

According to the structure of the present invention, the amount of the developer on the outermost surface is controlled to be low by adjusting the amount of the developer at the time of superimposing transfer of the color developer. Melting of the color developer is promoted, and color reproducibility is improved while suppressing color reproduction from increasing the load on the fixing device.

Further, when a problem such as a change in the environment or a temporary decrease in the development density due to a temporary delay in the replenishment of the color developer by the operator occurs in each of the developing units, the control of the amount of the color developer adhered by adjusting the developing bias voltage requires the target. There is a limit to the possibility of following color reproduction. Therefore,
By changing the fixing temperature of the fixing device, it is possible to perform color printing while maintaining the color reproducibility of the developing amount control means, for example, the control of the amount of adhered color developer by adjusting the developing bias voltage.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of the color image forming apparatus 1 in a cross section. FIG. 2 is a block diagram of a control system of the color image forming apparatus. The color image forming apparatus 1 has a central processing unit CPU that controls the entire main body, an image sensor (not shown) that reads an image (not shown) by a reading device, photoelectrically converts the read data, and converts image data of each color into each color. The first to fourth laser scanner units LSU, which are exposure means of an image forming unit described later, and image forming units F1 to F4 corresponding to colors.
F4, a storage device 2 for storing information on the developing devices in the image forming units F1 to F4, a conveying belt 3 for conveying a sheet below the image forming units F1 to F4, and the image forming units F1 to F4. It has color information detecting means 4a to 4d for detecting an identification mark 5c which is information of the developing device 5 in F4, and a fixing roller 8 which is a heating roller facing the downstream side of the conveyor belt 3.

The image forming units F1 to F4 for the respective colors include a developing unit 5 for storing a developer for each color and capable of being extracted from the apparatus main body 1, a guide member 6, and a photosensitive member 7. I have. Note that the image forming units F1 to F4 have the same configuration except for the configuration relating to the color of the developer (sometimes referred to as toner). In the present embodiment, a negatively charged toner is used as the developer, but a positively charged toner may be used.

The developing device 5 includes a developing tank 5a for storing the developer, a developing roller 5b disposed below the developing tank 5a, and for attaching the developer to the periphery and transporting the developer to the photosensitive member 7.
It has an identification mark 5c for distinguishing the color of the developer contained in the developing tank 5a.

The developing tank 5a contains a developer of each color of yellow, magenta, cyan or black, and rotatably supports a developing roller 5b at a lower portion.

The developing roller 5b is a conductive elastic roller made of conductive urethane rubber and is in contact with the photosensitive member 7 via a developer layer, and is rotated by a developing bias power supply (not shown) via a stainless steel shaft. A developing bias voltage of -450 (v) is applied.

The identification mark 5c, which is a color information presentation means,
Bar code information of color information formed at a predetermined position, or
It is formed by a mark or the like that directly represents each color. The color information presenting means may be a transparent window through which the developer in the developing device 5 can be seen. The identification mark 5c is
Is attached to the guide member 6 in which is stored, the identification mark 5c is read in the set state, and the color information is detected and identified.

When a bar code is used as the identification mark 5c, the color information detecting means 4a to 4d use a bar code reader or the like for reading bar code information. In the case of a color mark, it can be constituted by a photo sensor for identifying a color based on the amount of reflected light.

The guide member 6 is a housing member for accommodating the developing device 5 in the main body of the apparatus 1 in a removable manner. Therefore, when replacing the developing devices 5, the operator can remove all the developing devices 5 of the respective colors by the same operation, and attach new developing devices 5 of the respective colors by the same operation.

The negatively charged photoreceptor 7 is provided with a conductive substrate and is charged to a surface potential of, for example, -550 (v). During image formation, the photoconductor 7 is exposed by the laser scanner unit LSU, and image data is formed as an electrostatic latent image. Then, the electrostatic latent image is developed by the toner of the developing roller 5b based on the potential difference between the developing roller 5b and the photoconductor 7, and the toner image is further transferred to the sheet conveyed by the transfer conveying belt 3.

Next, the operation of the color image developing apparatus 1 will be described. When each of the developing devices 5 is set on each of the guide members 6, the color information of the identification mark 5c, which is a color information presenting means, is converted to color information detecting means 4a to 4 provided at corresponding positions.
d, each is detected, and the information is output to the CPU. The CPU recognizes, from the color information, which color developing unit 5 is mounted on the guide member 6 of each of the image forming units F1 to F4, and stores the image forming units F1 to F4 in the storage device 2.
The color information of the developing device 5 provided in F4 is stored.

When an image forming operation is instructed by operating means such as an operation panel and a keyboard (not shown), C
The PU converts image data of each color, which is output from a document reading unit such as a CCD and is subjected to predetermined image processing by an image processing unit (not shown), into an image forming unit F corresponding to each color.
1 to F4 first to fourth laser scanner units L
Output to SU respectively.

The laser beam output from each scanner unit LSU exposes each photoconductor 7 in the figure and proceeds to a developing process. In the development process, development transfer is performed sequentially from the upstream side in the traveling direction of the transfer conveyance belt 3. Here, as described above, the order in which the developing devices 5 are inserted and arranged in the main body 1 determines the order of the superimposition transfer, and the color toner of the developing device 5 arranged at the most downstream position in the superimposition transfer process. Adheres to the outermost surface of the sheet, and is most susceptible to heat on the surface of the heat roller of the fixing device 8. As a result, a change in the order in which the developing devices 5 are inserted, that is, the order in which the color toners are superimposed, causes a change in the color tone of the color print image. Thus, in the present embodiment, the control of the amount of toner adhered to each color is performed based on the arrangement pattern of the developing devices 5 of each color arranged in each of the image forming units F1 to F4.

FIG. 3 shows a developing tank 5 for yellow (Y), magenta (M), cyan (C), and black (K).
Considering the superposition order of the toners of the respective colors when expressing the colors of red (R), green (G) and blue (B) for the mounting order of 1 to 6 and the arrangement relationship of the developing tank 5a. 3 shows the amount of superposition of the color toner per unit area in the case of the above.

FIG. 4 shows a developing tank 5 for yellow (Y), magenta (M), cyan (C), and black (K).
a, the amount of superimposition of the color toners in three stages in the case of mounting order 1 to 6 is indicated by a symbol.
1, the next smallest amount is No. 2, and the smallest amount is No. 3.
It is shown as.

In the graph of FIG. 5, the abscissa represents the reflected image density information for defining the image density, the ordinate represents the control developing bias (-v) applied to the developing roller 5b, and the adhesion amount shown in FIG. The developing bias control curves No. 1 to No. 1 to 3 for each of the yellow (Y), magenta (M), cyan (C), and black (K) developing tanks 5a.
1 to No. 3 are shown. Therefore, the developing bias voltage is determined according to the developing bias control curves No. 1 to No. 3, and the developing bias driving device 10 (FIG. 2) controls the developing bias voltage of the developing roller 5b for each color under the control of the CPU. The reflection image density information can be obtained by detecting the color toner image reflection density on the surface of each photoreceptor 7, the surface of a paper (transfer material), or the surface of the transfer conveyance belt 3 after development or development and transfer.

FIG. 6 shows the vividness of each color of red (R), green (G), and blue (B) when the control developing bias is applied to the mounting order 1 to 6 of each developing tank 5a and when it is not performed. It is a graph which shows a change.

In the method of selecting the developing bias voltage control curve, the arrangement of the developing devices 5 is recognized by the signals of the developing device color information detecting means a to 4d shown in FIG. A developing bias voltage control curve is selected based on the array storage information of the developing device 5.

The determination of the developing bias voltage at the time of developing each color toner is carried out, for example, at the time of starting up the main body of the machine. The developing bias voltage at the time of developing each color toner is determined by using the reflection density information obtained from the detection result of 2) and the control curve selected previously.

The developing bias driving device 10 applies the determined developing bias voltage to the developing device 5 in accordance with each process timing.
When the output control is performed as described above, the adhesion amount control of each color toner shown in FIG. 3 is executed, and as shown in FIG. 6, the vivid color reproducibility is not accompanied by a drastic change of the current apparatus body 1 and each image forming process. To be realized.

Specifically, in the case where YMCK is arranged from the upstream side as the mounting order 1 of the developing tank 5a, the adhesion amounts of magenta (M) and cyan (C) are smaller than the adhesion amounts of yellow (Y). I do. In this case, cyan (C) and magenta (M) are No. 2, yellow (Y) and black (K) are No. 1, and the control development bias is CP.
U is applied to each developing roller 5b under the control of the developing bias driving device 10 to execute development of each color.

Similarly, in the case of YCMK arrangement from the upstream side as the mounting order 2 of the developing tank 5a, the adhesion amount is increased in the order of magenta (M), cyan (C), and yellow (Y).
In this case, cyan (C) is No. 2 and magenta (M)
Is No. 3, and yellow (Y) and black (K) are No. 1. Similarly, a control developing bias is applied to each developing roller 5b to execute development of each color.

In the case where MYCK is arranged from the upstream side as the mounting order 3 of the developing tank 5a, the adhesion amount of cyan (C) is made smaller than the adhesion amount of magenta (M) and yellow (Y). In this case, cyan (C) is No. 2 and magenta (M), yellow (Y) and black (K) are No. 1. Similarly, a control developing bias is applied to each developing roller 5b, and Execute development.

When MCYK is arranged from the upstream side as the mounting order 4 of the developing tank 5a, the adhesion amounts of cyan (C), magenta (M), and yellow (Y) are made the same. In this case, all the colors become No. 1, and similarly, a control developing bias is applied to each developing roller 5b to execute development of each color.

When CMYK is arranged from the upstream side as the mounting order 5 of the developing tank 5a, the amount of magenta (M) is made smaller than the amount of cyan (C) and yellow (Y). In this case, magenta (M) is No. 2, cyan (C), yellow (Y), and black (K) are No. 1. Similarly, a control developing bias is applied to each developing roller 5b, and Execute development.

Finally, also in the case where the CYMKs are arranged from the upstream side in the mounting order 6 of the developing tanks 5a, the amount of magenta (M) is made smaller than the amount of cyan (C) and yellow (Y). Also in this case, magenta (M) is No. 2 and cyan (C), yellow (Y) and black (K) are No. 1.
Similarly, the control developing bias is applied from the developing bias driving device 10 to each of the developing rollers 5b to execute the development of each color.

Next, referring to FIGS. 2, 7, and 8, even if the developing function of each color developing unit 5 is insufficient and it is difficult to control the amount of adhered color toner by adjusting the developing bias voltage, etc. A case in which better color image quality is provided by changing the set temperature of the heating heat roller of the apparatus 8 will be described.

In FIG. 7, the horizontal axis represents image input data, the vertical axis represents print image density (ID), and the developing bias voltage is -40.
The reproduction density curves of the halftone images of each color when set to 0 (v) and when set to -300 (v) are shown. In general, in the two-component developing method, the developing property is controlled by changing the developing bias voltage.
As shown in (1), there is a problem that only the saturation density changes and the balance of the entire halftone reproduction characteristic changes. Since this is not the originally intended halftone reproduction characteristic, it is not preferable in terms of color image quality. The reason is that the electric field concentrates on the peripheral portion of the image of the electrostatic latent image generated at the time of reproducing the dot image at the time of laser writing, and the electric field concentrates on that portion, so that the image is largely developed at the time of development. On the other hand, in the saturated density portion, since there is no electric field concentration in the peripheral portion of the image, developability in proportion to the development bias voltage can be obtained.

In order to solve the above problems, while controlling the developing property of the developing device by controlling the developing bias voltage, as shown in FIG.
The fixing roller set temperature for No. 6 is also changed and controlled in a plurality of stages such as Hi / Lo. In particular,
In the case of the mounting order 4, the fixing temperature of the fixing heater driving device 12 (FIG. 2) of the fixing device 8 is set to Lo, and in the other mounting orders 1, 2, 3, 5, and 6, the fixing heater is set. The fixing temperature setting of the driving device 12 is Hi.

As a result, as shown in FIG. 7, good color image reproduction characteristics were obtained over the entire halftone reproduction characteristics without lowering the saturation density. The fixing temperature setting is shown in FIG.
Since only a specific combination of developer colors is carried out as shown in the above, unnecessary energy is not consumed, and if necessary, the operator is displayed on the display device 13 to change to the optimum developing device arrangement. It is also possible to encourage.

Although the preferred embodiment of the present invention has been described in the above embodiment, it goes without saying that the present invention is not limited to this.

[0040]

As described above, according to the first and second aspects of the present invention, there is provided an image developing apparatus which minimizes a change in the color tone of a final multi-color printed image regardless of the arrangement order of the developing devices. did it. According to the third aspect of the present invention, even when the developing function of each developing device is insufficient and it is difficult to control the amount of color developer to be applied properly by adjusting the developing bias voltage, better multi-color image quality is maintained. Image development device.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a color image forming apparatus according to an embodiment of the present invention in cross section.

FIG. 2 is a control block diagram of the color image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating the relationship between the mounting order 1 to 6 of the developing tank 5a for each color according to the embodiment of the present invention and the toner of each color when expressing the colors of red (R), green (G), and blue (B). FIG. 9 is an explanatory diagram showing an overlapping amount per unit area of a color toner in consideration of an overlapping order and an arrangement relationship of a developing tank 5a.

FIG. 4 is an explanatory diagram in which the overlapping amounts of the color toners in the mounting orders 1 to 6 of the developing tanks 5a for each color according to the embodiment of the present invention are indicated by symbols in three stages.

FIG. 5 is a graph in which the horizontal axis represents reflected image density information defining image density, and the vertical axis represents control development bias (-v) applied to the developing roller 5b. FIG. 6 is an explanatory diagram of development bias control curves No. 1 to No. 3 for each color developing tank 5a for realizing the above.

FIG. 6 shows red (R), green (G), and blue (B) when a control developing bias is applied to the mounting order 1 to 6 of the developing tank 5a for each color according to the embodiment of the present invention and when it is not performed. FIG. 4 is an explanatory diagram showing a change in vividness for each color.

FIG. 7 is a diagram illustrating a halftone image of each color when the horizontal axis represents image input data, the vertical axis represents print image density, and the developing bias voltage is set to −400 (v) and −300 (v). FIG. 3 is an explanatory diagram showing a density curve.

FIG. 8 is an explanatory diagram showing a fixing temperature setting of the fixing roller 8 with respect to the mounting order 1 to 6 of the developing tank 5a for each color according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 color image forming apparatus CPU central processing unit F1 to F4 image forming unit LSU laser scanner unit 2 storage device 3 transfer and conveyance belt 4a to 4d color information detecting means 5 developing unit 5b developing roller 5c identification mark 6 guide member 7 photosensitive member 8 fixing Roller 10 Developing bias driving device 11 Reflection density information means 12 Fixing heater driving device

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Yoshida 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 2H030 AB02 AD04 AD16 BB23 BB24 BB33 BB34 BB36 2H073 AA02 BA22 BA45 CA22 2H077 AD35 BA08 BA09 BA10 DA24 DB08 DB14 EA24 GA13

Claims (3)

[Claims] 1. An electrostatic latent image carrier, exposure means for forming an electrostatic latent image on the electrostatic latent image carrier, and a developer having the formed electrostatic latent image therein. A plurality of image forming units each including a developing unit for visualizing are arranged in accordance with each color, a plurality of developing units in each of the image forming units are provided detachably with respect to the apparatus main body, and each developing unit is optional. An image forming apparatus having a developing device storage portion that can be stored and arranged in a storage portion of the image forming apparatus, wherein a developing device array detecting device that detects an arrangement order of the developing devices stored in the storing device, and a detection result of the developing device detecting device. Development in which the amount of developer to be developed by each of the developing units is controlled to be changed to a predetermined amount of a developing agent for each of the developing units or to an amount of a developing agent based on a predetermined rule based on an arrangement order of a certain developing unit. Volume control means;
An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein said developing amount control means is a developing bias control device for controlling a developing bias voltage of each developing device. 3. A fixing device for fixing a developer image formed on the transfer material to the transfer material by heating, and fixing the developer image based on an arrangement order of the developing devices detected by the developing device arrangement detecting means. 3. The image forming apparatus according to claim 1, wherein the fixing temperature of the apparatus is changed and controlled.