JP3608760B2 - Color toner supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color toner replenishing device applied to an image forming apparatus using a two-component developer such as a copying machine or a printer.
[0002]
[Prior art]
To detect the amount of toner replenished to the developing device, the amount of toner developed on the pattern on the electrostatic latent image carrier is detected by an optical sensor, and the toner in the developing device is detected according to the amount of toner attached. A technique for controlling the replenishment amount is known (see, for example, JP-A-61-201276).
[0003]
In such a technique, an optical sensor in which the light emission angle and the incident angle with respect to the measurement surface are equal (regular reflection method) is generally used (see FIG. 7).
[0004]
[Problems to be solved by the invention]
It is known that the regular reflection type optical sensor has different output characteristics when black toner is used and output characteristics when color toner is used (see FIG. 8).
[0005]
That is, as shown in the figure, when looking at the relationship between the toner adhesion amount M and the sensor output VM, the output characteristic for black toner shows a monotonous decrease over the entire area of the toner adhesion amount on the pattern. The output characteristic for the color toner shows a minimum value (Vmin) at a predetermined toner adhesion amount, and the output characteristic differs greatly before and after this minimum value. In other words, the toner has a relatively sharp monotonous decrease curve on the low adhesion amount side (A region) with respect to this minimum value, while the relatively slow monotonous increase curve on the high adhesion amount side (B region). Indicates. Vsg indicates an output when there is no toner on the photosensitive member.
[0006]
Due to these characteristics, in the conventional technique, the replenishment amount of toner is controlled using only the low adhesion amount region where the characteristic sensitivity of the output of the optical sensor is relatively high.
[0007]
In the conventional techniques as described above, if the toner adhesion amount on the latent image depends only on the toner amount in the developer, the toner supply amount can be accurately adjusted.
[0008]
However, since the characteristics of the two-component developer generally vary depending on the environment over time, the toner adhesion amount on the latent image does not depend only on the toner amount in the developer. There is a problem that accurate adjustment of the supply amount cannot be performed stably.
[0009]
Specifically, the conventional developer has a characteristic that the charge amount per unit weight of the initial developer (hereinafter referred to as “q / m”) is high and the q / m decreases with time deterioration. When the technology is applied, even if the amount of toner in the developer is the same, the amount of toner adhering to the pattern is small because q / m is initially large, so that the toner density is adjusted to be higher. On the other hand, when q / m becomes smaller due to the subsequent change with time, the toner adhesion amount on the pattern increases, so that the toner density is adjusted to be lower.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to provide a color toner supply device capable of stably controlling the amount of color toner supplied.
[0011]
Another object of the present invention is to secure a stable toner replenishment control operation by setting a color toner replenishment amount to be controlled in a region where the output characteristic sensitivity is high.
[0012]
Another object of the present invention is to secure a stable control operation of toner replenishment by controlling the toner adhesion amount detection in the monotonically decreasing region based on the output characteristics in the monotonically increasing region.
[0013]
Another object of the present invention is to secure a stable control operation of toner replenishment by controlling the target value of toner replenishment in the monotonically decreasing region based on the output characteristics in the monotonically increasing region.
[0014]
Another object of the present invention is to detect a toner density based on output characteristics in a monotonically increasing region, and to enable a stable control operation of toner supply.
[0015]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided an electrostatic latent image carrier, a two-component multicolor developing device, a toner replenishing means for supplying color toner to the two-component multicolor developing device, and the electrostatic latent image carrier. A toner adhering means for detecting the toner density formed by the electrostatic latent image, a specular reflection type optical sensor for detecting the toner adhering amount of the toner adhering means, and a predetermined sensor based on the output of the optical sensor. Control means for controlling a control target and adjusting toner supply by the toner supply means, and the adjustment by the control means is based on outputs having different characteristics of the optical sensor when the detection target is a color toner. The control is performed by controlling different types of control objects.
[0016]
Therefore, by controlling not only the area where the output of the optical sensor shows a monotonous decrease characteristic but also the output characteristic of the area where the monotonous increase characteristic is controlled, it is possible to cope with fluctuations in the developer characteristics over time and the environment. In addition, it becomes possible to stabilize the control of the color toner replenishment compared to the conventional case.
[0017]
The invention described in claim 2 is characterized in that, in a region where the output of the optical sensor shows a monotonously decreasing characteristic as the color toner adhesion amount increases, the control object is the replenishment amount of the color toner.
[0018]
Therefore, in the monotonously decreasing region where the output characteristic sensitivity of the optical sensor is high, a stable control operation of toner replenishment can be ensured by setting the control target to the color toner replenishment amount.
[0019]
According to a third aspect of the present invention, in a region where the output of the optical sensor exhibits a monotonically increasing characteristic as the color toner adhesion amount increases, the toner patch pattern in the monotonically decreasing region based on the output characteristic in the monotonically increasing region is controlled. It is characterized by the correction amount of the image forming potential.
[0020]
Therefore, by controlling the correction amount of the image forming potential of the toner adhering means in the monotonically decreasing area based on the output characteristics in the monotonically increasing area, the toner density can be kept stable and at the same time the amount of toner adhering to the toner adhering means can be reduced. It is possible to ensure a stable control operation of toner replenishment.
[0021]
According to a fourth aspect of the present invention, in a region where the output of the optical sensor exhibits a monotonically increasing characteristic as the color toner adhesion amount increases, the toner patch pattern in the monotonously decreasing region is controlled based on the output characteristics in the monotonously decreasing region. It is a developing bias.
[0022]
Therefore, by controlling the developing bias of the toner adhering means in the monotonously decreasing area based on the output characteristics in the monotonically increasing area, the toner density can be kept stable and at the same time the amount of toner adhering to the toner adhering means is adjusted to It is possible to ensure a stable control operation of replenishment.
[0023]
The invention described in claim 5 is characterized in that, in a region where the output of the optical sensor exhibits a monotonically increasing characteristic as the amount of color toner adhesion increases, the control target is set as a correction amount of the color toner replenishment target value.
[0024]
Therefore, by correcting the toner replenishment target value based on the output characteristics in the monotonically decreasing region based on the output characteristics in the monotonically increasing region, it is possible to ensure a stable toner replenishing control operation.
[0025]
According to a sixth aspect of the present invention, the correction is performed based on a difference between the minimum value of the output characteristic of the optical sensor and the output value of the optical sensor when the maximum laser light amount is written on the toner adhering means. It is characterized by.
[0026]
Such a difference is almost directly proportional to the toner density (see FIG. 5) and is not influenced by the characteristics of the developer.
[0027]
Therefore, the toner density is stabilized by controlling the correction amount of the image forming potential of the adhering portion, the developing bias, and the correction target value of the toner based on this difference, thereby ensuring stable control operation of the toner supply. It becomes possible to do.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment of the Invention
The first embodiment of the present invention is an example in which, in a region where the output of the optical sensor exhibits a monotonous decrease characteristic, the control target is a developing bias of the toner adhering means in the monotonous decrease region.
[0029]
As shown in FIG. 1, the electrostatic latent image carrier 2 of the image forming apparatus 1 has a photosensitive layer on the surface of an aluminum substrate, and this photosensitive layer is uniformly charged by a charging device 3. The laser diode 10 emits a laser beam having a light intensity corresponding to the image data, and forms an electrostatic latent image corresponding to the image on the electrostatic latent image carrier 2.
[0030]
The developing unit (two-component multicolor developing device) 4 is a revolver-like rotary type and includes four developing tanks 41, 42, 43, and 44 therein. Each developing tank is composed of four colors of yellow (hereinafter referred to as “Y”), magenta (hereinafter referred to as “M”), cyan (hereinafter referred to as “C”), and black (hereinafter referred to as “K”). Contains component developer inside. A developing bias is applied to the developing sleeves in the developing tanks 41, 42, 43, and 44, and toner is supplied onto the image carrier 2 to develop and develop toner corresponding to the latent image potential. Image.
[0031]
The toner image visualized on the electrostatic latent image carrier 2 as described above is transferred to the transfer belt 5. At this time, an appropriate amount of toner can be transferred by applying an appropriate bias to the primary transfer roller 7. Then, the above-described charging, exposure, development, and transfer processes are repeated in the order of K, C, M, and Y in the order of four colors, thereby forming an overlapping image with four color toners on the transfer belt 5. Is done.
[0032]
Reference numeral 8 denotes a fixing device including a pair of rollers 8a and 8b. The four color toner image is transferred onto the recording paper P at a time, and then heated and pressed by the fixing device 8. The final created image is obtained.
[0033]
In a non-image forming area on the photosensitive surface of the electrostatic latent image carrier 2, a predetermined patch pattern (details will be described later) corresponding to the toner adhering means of the present invention with a predetermined laser light amount and developing bias is latent image. Formed as. The optical sensor 9 is of a regular reflection type in which the light emission angle and the incident angle with respect to the measurement surface are equal, and detects the amount of color toner adhering to the patch pattern in the development process.
[0034]
As shown in FIG. 2, in the control system of the image forming apparatus 1, the ROM 12, the RAM 13, the actuator 14, and the optical sensor 9 are connected to the bus etc. 15 with respect to the CPU 11 corresponding to the control means of the present invention. (I / O interface and the like are not shown).
[0035]
The ROM 12 stores various programs for controlling each part of the image forming apparatus 1 and fixed data. In particular, there are stored programs relating to the formation of patch patterns on the image carrier 1, the calculation performed based on the detection result of the optical sensor 9, the control performed based on the calculation result (both described later), and the like.
[0036]
The actuator 14 is an actuator that is provided in the developing unit 4 and supplies the color toner of each color into the developing tanks 41, 42, 43, and 44, and corresponds to the toner replenishing means of the present invention. Is. Specifically, for example, a motor that rotates a roller for supplying toner is used. Various other sensors and actuators are connected to the CPU 11, but illustration and description thereof are omitted.
[0037]
In such a configuration, toner replenishment control performed by the image forming apparatus 1 having the above configuration will be described with reference to FIGS.
[0038]
As shown in FIG. 3, when the image forming apparatus 1 is not turned on immediately or after a job exceeding a predetermined image forming interval is completed, the electrostatic latent image carrier 2 is not formed. A patch pattern for detecting the toner adhesion amount is created in the image area with a predetermined developing bias and laser light quantity (steps S1 and S2).
[0039]
A predetermined set value is corrected immediately after the power is turned on or after completion of a job exceeding a predetermined image forming interval (steps S1 and S3). In the first embodiment of the present invention, the predetermined set value is the predetermined developing bias, and the amount of adhesion is determined using a developing bias value obtained by adding a predetermined correction to the predetermined developing bias. A patch pattern for detection is created (step S2). Details of step S3 will be described later.
[0040]
After creating the patch pattern for detecting the adhesion amount, the optical sensor 9 detects the toner adhesion amount of the patch pattern (step S4). Then, it is determined from the sensor output whether the toner adhesion amount has reached the target value (step S5). Specifically, the control target value of the toner adhesion amount is Mo (g / cm ² ), and the corresponding toner adhesion amount in FIG. 8 when the sensor detection value is Vs (V) is Ms (g / cm ^2). ), A necessary toner replenishment amount M is defined by the following equation.
[0041]
M = MA × (Mo−Ms) (1)
Here, MA is a proportionality constant, which is a value obtained experimentally corresponding to a specific design of the image forming apparatus.
[0042]
In equation (1), the toner adhesion amount on the patch pattern decreases as the toner decreases due to consumption, so an amount of toner proportional to the difference between the target toner adhesion amount and the actual detected adhesion amount is compensated. It is something to try. Then, a predetermined control signal is sent from the CPU 11 to the actuator 14, and an amount of toner corresponding to the replenishment amount M calculated by the equation (1) is replenished (step S6).
[0043]
Next, the step S3 that characterizes the first embodiment of the present invention will be described in detail. As shown in FIG. 4, first, a patch pattern for detecting a correction value is created in a non-image forming area of the electrostatic latent image carrier 2 (step S31). This patch pattern is different from the above-described one for detecting the toner adhesion amount, and is based on potentials and writing values set in advance so as to cover the entire area from the monotonously decreasing area A to the monotonically increasing area B in FIG. Create several. Then, the toner adhesion amount on each patch pattern is detected by the sensor 9 (step S32).
[0044]
Then, the toner adhesion amount (see FIG. 8) corresponding to the minimum value among the detected values is selected as the minimum value Vmin, and the toner adhesion amount corresponding to the output value of the patch pattern written with the maximum laser light amount is selected. The maximum value Vmax is set (step S33). Then, (Vmax−Vmin) is calculated (step S34). As shown in FIG. 5, the difference between the maximum value Vmax and the minimum value Vmin is substantially directly proportional to the toner density, and is not affected by the characteristics of the developer. In the figure, toner scattering occurs when the toner concentration exceeds T1, and carrier adhesion occurs when the toner concentration falls below T2. Therefore, the values (Vmax−Vmin) corresponding to the toner densities T1 and T2 are set as A1 and A2, respectively, and the values (Vmax−Vmin) actually obtained from the detected values are compared with A1 and A2 (step S35). In order to create a patch pattern for detecting the toner adhesion amount, a value obtained by adding a predetermined correction to the predetermined development bias value (VB) is selected as a development bias value (steps S36, S37, S38). .
[0045]
That is, first, the region exceeding A1 in FIG. 5 is a region where toner scattering occurs with respect to the mechanical characteristics of the developing tanks 41, 42, 43, and 44. Since toner scattering causes image smearing, it is necessary to reduce the toner density in this case. Therefore, a value obtained by increasing the preset developing bias value VB by a predetermined amount β1 is selected as the developing bias value (step S36). As a result, a patch pattern for detecting the toner adhesion amount is created with a higher development bias than usual (step S2), and the toner adhesion amount can be increased, so that the toner is not easily replenished, resulting in a decrease in toner density. (Steps S5 and S6).
[0046]
In FIG. 5, the area below A2 is an area where the toner concentration is low and carrier adhesion occurs, so it is necessary to increase the toner density. Therefore, in this case, a value obtained by reducing the predetermined developing bias value VB by a predetermined amount β2 is selected as the developing bias value (step S38). As a result, a patch pattern for detecting the toner adhesion amount is created with a developing bias lower than usual (step S2), and the toner adhesion amount can be reduced, so that the toner density can be increased by supplying toner (step S2). S5, S6).
[0047]
Further, in FIG. 5, when the value of (Vmax−Vmin) is within the range of A1 to A2, the toner density is within the allowable range of the developing tanks 41, 42, 43, and 44. The development bias value VB that has been set is not corrected, and a patch pattern for detecting the toner adhesion amount is created based on the preset development bias value VB (step S2).
[0048]
As described above, according to the first embodiment of the present invention, the toner density is determined by obtaining (Vmax−Vmin) based on the output characteristics of the monotonically increasing region of the optical sensor 9, and thus has not been conventionally performed. The developing bias VB of the patch pattern for detecting the toner adhesion amount is corrected. Since (Vmax−Vmin) is directly proportional to the toner density and does not depend on the characteristics of the developer or the like, the toner adhesion amount of the detection patch pattern is adjusted based on (Vmax−Vmin), and the monotonous decrease of the optical sensor 9 is achieved. The toner supply amount (conventionally unchanged) controlled based on the output characteristics of the region is adjusted. As a result, the toner density is optimally maintained, and a stable control operation for color toner replenishment is possible.
[0049]
[Second Embodiment of the Invention]
The embodiment of the present invention is an example of the invention for correcting the toner replenishment target value based on the output characteristics in the monotonously increasing region.
[0050]
The apparatus configuration of the second embodiment of the present invention is the same as the apparatus configuration of the first embodiment described with reference to FIGS. 1 and 2, and thus detailed description thereof is omitted. Further, the processing procedure in the second embodiment is the same as that of the invention described above with reference to FIGS. 3 and 4, except that the processing of steps S41 to S44 is performed instead of steps S35 to S38, as shown in FIG. Since this is the same as that of the first embodiment, detailed description thereof is omitted. Hereinafter, steps S41 to S44 that characterize the second embodiment of the present invention will be mainly described.
[0051]
First, the values of (Vmax−Vmin) obtained in the same manner as described above are the values B1 and B2 shown in FIG. 5 (these values have the same meanings as A1 and A2, and are the same as A1 and A2. (Or different values) (step S41). Then, in order to create a patch pattern for detecting the toner adhesion amount, the predetermined control target value obtained by adding a predetermined correction to Mo is selected as a control target value (steps S42, S43, S44). .
[0052]
That is, first, since it is necessary to decrease the toner density in the region exceeding B1 in FIG. 5, when the value of (Vmax−Vmin) is larger than B1, the preset control target value Mo is set to the predetermined amount γ1. The increased value is selected as a control target value (step S42). This makes it difficult to determine that the toner adhesion amount determined from the sensor output has reached the corrected target value in step S5, so that the toner is not replenished (step S6). The concentration can be reduced.
[0053]
Further, since it is necessary to increase the toner density in the region below B2 in FIG. 5, when the value of (Vmax−Vmin) is smaller than B2, the preset control target value Mo is decreased by a predetermined amount γ2. A value is selected as a control target value (step S44). This makes it easy to determine that the toner adhesion amount has reached a control target value lower than normal (step S5), so that the toner is not replenished (step S6), and as a result, the toner density can be increased.
[0054]
Further, in FIG. 5, when the value of (Vmax−Vmin) is within the range of B1 to B2, the toner concentration is within the allowable range of the developing tanks 41, 42, 43, and 44. The control target value Mo is not corrected (step S43), and the comparison in step S5 is performed using the normal control target value Mo.
[0055]
As described above, according to the second embodiment of the present invention, the toner density is determined by obtaining (Vmax−Vmin) based on the output characteristics of the monotonically increasing region of the optical sensor 9, and thus the toner that has not been changed in the past. The target value of supply is adjusted. Therefore, it is possible to maintain the toner density optimally and perform a stable control operation of the color toner replenishment amount.
[0056]
【The invention's effect】
According to the first aspect of the invention, since the output of the optical sensor is controlled using not only the detection region showing the monotonous decrease but also the output characteristic of the detection region showing the monotonous increase, the characteristics of the developer depending on the time and environment. Therefore, it is possible to perform a control operation that is more stable than conventional color toner replenishment.
[0057]
According to the second aspect of the invention, in the first aspect of the invention, in the region where the output characteristic sensitivity of the optical sensor is high, the control target is the color toner replenishment amount, so that stable control operation of toner replenishment is ensured. can do.
[0058]
According to the invention described in claim 3, in the invention described in claim 2, the correction amount of the image potential of the toner patch pattern in the monotonically decreasing region is controlled based on the output characteristics in the monotonously increasing region. It is possible to secure a stable control operation of toner replenishment by adjusting the amount of adhered toner.
[0059]
According to the invention described in claim 4, in the invention described in claim 2, since the development bias of the toner patch pattern in the monotonically decreasing area is controlled based on the output characteristics in the monotonically increasing area, the amount of adhered toner is reduced. It is possible to ensure a stable control operation of toner replenishment by adjusting.
[0060]
According to the fifth aspect of the present invention, in the second aspect of the invention, the toner supply target value based on the output characteristics in the monotonically decreasing region is corrected based on the output characteristics in the monotonically increasing region. It is possible to ensure the controlled operation.
[0061]
According to a sixth aspect of the present invention, in the invention according to any one of the third, fourth, and fifth aspects, the optical sensor when writing to the toner adhering means with the minimum value and the maximum laser light amount of the output characteristic of the optical sensor Since the object to be controlled is controlled based on the difference from the output of the toner, it is possible to stabilize the toner density and ensure a stable control operation for toner supply.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an overall apparatus configuration of an image forming apparatus according to first and second embodiments of the present invention.
FIG. 2 is a block diagram showing a control system according to the first and second embodiments of the present invention.
FIG. 3 is a flowchart for explaining the operation of the first and second embodiments of the present invention;
FIG. 4 is a flowchart for explaining the operation of the first and second embodiments of the present invention;
FIG. 5 is a diagram for explaining the relationship between toner density and (Vmax−Vmin) in the first and second embodiments of the present invention;
FIG. 6 is a flowchart for explaining the operation of the first embodiment of the present invention.
FIG. 7 is a diagram illustrating a regular reflection type optical sensor;
FIG. 8 is a diagram for explaining the relationship between the adhesion amount of black toner and color toner and the output of a regular reflection type optical sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Electrostatic latent image carrier 4 Developing unit (2 component multi-color developing device)
9 Optical sensor 11 CPU (control means)
14 Actuator (toner supply means)
Vmax Maximum value Vmin Minimum value VB Development bias Mo Control target value

Claims (6)

An electrostatic latent image carrier;
A two-component multicolor developing device;
Toner supply means for supplying color toner to the two-component multicolor developing device;
A toner adhering means for adhering a toner patch pattern for detecting the toner density formed on the electrostatic latent image carrier with an electrostatic latent image;
A specular reflection type optical sensor for detecting the amount of toner attached to the toner patch pattern ;
Control means for controlling a predetermined control object based on the output of the optical sensor and adjusting toner supply by the toner supply means,
The color toner replenishing apparatus according to claim 1, wherein the adjustment by the control means is performed by controlling different types of control objects based on outputs having different characteristics of the optical sensor when the detection object is a color toner. 2. The color toner replenishing device according to claim 1, wherein in a region where the output of the optical sensor exhibits a monotonously decreasing characteristic as the color toner adhesion amount increases, the control target is a color toner replenishment amount. In an area where the output of the optical sensor exhibits a monotonically increasing characteristic as the amount of color toner attached increases, the control target is set as the correction amount of the image potential of the toner patch pattern in the monotonically decreasing area based on the output characteristics in the monotonically increasing area . The color toner replenishing device according to claim 2. In a region where the output of the optical sensor shows a monotonically increasing characteristic as the amount of color toner adhered increases, the development target of the toner patch pattern in the monotonically decreasing region based on the output characteristics in the monotonically decreasing region is a control target. The color toner replenishing device according to claim 2. 3. The color toner replenishing device according to claim 2, wherein in a region where the output of the optical sensor shows a monotonously increasing characteristic as the amount of color toner adhering increases, the control target is set as a correction amount of the color toner replenishment target value. The correction is performed based on a difference between the minimum value of the output characteristic of the optical sensor and the output value of the optical sensor when writing to the toner adhering means with the maximum laser light quantity. The color toner replenishing device according to any one of the above.

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