JPH09230642A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Object] When fuzzy inference is used for control of a controlled object, a membership function used for the control is fixed at the time of designing, so an appropriate control condition is set for each controlled object. Prevent being unable to do. SOLUTION: The data relating to the membership function for fuzzy inference stored in the information storage means 8 of the control unit 1 installed in the controlled object or the external input means 10 of the membership function itself is used for modification. It is characterized by enabling the control conditions for each controlled object.

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, and more particularly to an image forming apparatus having a control target capable of fuzzy control.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus, in particular, an image forming apparatus using an electrophotographic copying method, toner can be used to electrostatically form an electrostatic latent image formed on a photoconductor which is a latent image carrier. Visual image processing is performed, and the visible image is electrostatically transferred onto a recording sheet to obtain a copy.

By the way, the image forming apparatus is controlled such that the state quantity is corrected or appropriately adjusted according to the change of the state quantity. One of such control targets is a developing device.

The developing device is required to always maintain a constant toner density in order to prevent a change in image density. Therefore, in order to make the toner concentration contained in the developing device constant, for example, when using a two-component developer in which a toner and a carrier are mixed, the amount of toner supplied to the developer is replenished. The supply time, which is a factor that determines the

To control the toner replenishment time, the drive time of the drive source of the replenishment member provided in the toner replenishment section is controlled, and the toner concentration in the developing device is changed depending on the content or the photoconductor. The drive time is set by detecting the change in the image density above. One of the toner replenishment controls is feedback control in which the image density on the photoconductor or the toner content in the developing device is monitored and the monitoring result is used for on / off control of the drive source.

However, in the feedback control, the operation amount (driving amount) may not match the actual state amount. This is because the state amount detection error and the response delay in the drive source are the causes, and the toner density may differ from the predetermined density.

On the other hand, the toner density control may be performed not only by using the threshold value as a reference as in the above feedback control but also by using a reference other than the threshold value. That is, the density of the image density may be subjectively judged, and in this case, the replenishment time may be controlled between the threshold values by subjective information. For example, this control corresponds to slightly increasing or slightly decreasing the toner density depending on whether the toner density is slightly lower or slightly higher than the appropriate value.

Conventionally, it has been proposed that the relationship between such an ambiguous state quantity and the manipulated variable is related using fuzzy reasoning to obtain and control the manipulated variable (driving amount). The target for performing fuzzy control using such fuzzy reasoning may be not only the above-described developing device but also the charging potential of the photoconductor and a fixing device used for fixing an image after transfer. (For example, JP-A-3-89369).

[0009]

However, in the case of the fuzzy control based on the fuzzy inference that is usually used, the state quantity (x) used in the fuzzy inference and the degree to which the state quantity (x) is the concept A are. The membership function (μ _A (x)), which is a function of, is registered as a fixed value at the design stage. Therefore, for example, when a highly sophisticated and complicated adjustment of toner density is performed by a serviceman, the member Since it is limited to the ship function, various adjustments may not be possible.

Particularly, in the image forming apparatus such as a copying machine which has different usage conditions after shipping, the toner density adjustment is different, and the toner density adjustment is required to be suitable for the apparatus. Since the number is large, it is desired to optimally adjust the toner density in the image forming apparatus.

On the other hand, in order to be able to adjust the toner density of each toner, it is necessary to prepare a huge number of parameters, resulting in an increase in the cost required for the configuration for that purpose.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem of fuzzy control in an image forming apparatus, and an object thereof is to provide an image forming apparatus capable of performing fuzzy control unique to each image forming apparatus.

[0013]

According to the first aspect of the present invention,
Controlled amount detecting means for detecting a controlled amount of a controlled object, state amount detecting means for detecting a state amount related to the controlled amount detected by the controlled amount detecting means, and control of the controlled object The operation amount control means having a function of inputting or displaying the operated amount and the control program for controlling the controlled amount are stored, and the relationship between the state amount and the operated amount is related as a qualitative rule. Storage means for storing inference rules, information storage means for storing the manipulated variables and calculation data, and data for the inference rules input from external input means connected outside the apparatus, and the control program And an arithmetic control processing means for executing arithmetic control processing by means of the control means, which is provided in an apparatus having a controlled object, and the state quantity and the operation quantity are at least one member. In an image forming apparatus having function storage means expressed by a function and controlled by fuzzy inference, the membership function used by the external input means is changed with the original membership function as a reference value. The feature is that only the value to be corrected is changed.

According to a second aspect of the invention, in the image forming apparatus according to the first aspect, the parameter changed by the external input means is the correction value itself of the membership function.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, in the image forming apparatus according to the first aspect, the object whose input is changed by the external input means is
It is characterized in that it is an input value that is changed stepwise in advance.

According to a fourth aspect of the invention, in the image forming apparatus according to the first aspect, the membership function-related data for the device having the controlled object is displayed by the input means.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is a block diagram for explaining the configuration of a control unit used in the image forming apparatus according to the present invention. The control unit 1 shown in FIG. 1 is a copying machine of the image forming apparatus. It is intended to control the toner density of the developer used in some cases. Therefore, in the control unit 1,
As will be described in detail later, the amount of change in toner concentration is the target of the current state amount, and the time for operating the drive motor of the toner replenishment unit by fuzzy reasoning, which will be described later, that is, the replenishment time is the target of the manipulated variable.

In FIG. 1, the control unit 1 has a CPU 2 which is an arithmetic control processing unit equipped on the copying machine side. The CPU 2 has an I / O interface 3,
3'4, 4'on the input side, a state quantity detecting means 5 for detecting the toner density and an operation corresponding to an operation quantity controlling means provided with an operation amount input section and a display section for control described later The unit 6 is connected to the output side, and the drive unit 7 of the drive motor of the supply unit included in the developing device is connected to the output side.

The state quantity detecting means 5 uses an optical sensor for optically detecting the toner concentration of the developer, and the operating section 6 is an operating panel equipped in the main body of the copying machine. A density adjustment key is provided as related to the embodiment. The state amount detecting means 5 is not limited to the optical type, but in the case of a two-component developer using a magnetic carrier,
It is also possible to use a magnetic sensor that detects a magnetic coefficient that changes depending on the mixing ratio of the toner and the carrier.

Further, the CPU 2 has an RO as a storage means for storing a control program executed by the control unit 1.
An M8, a RAM 9 as an information storage means for storing the manipulated variable and the operation data, and an external input means 10 using a personal computer or the like connected by an RC232C connector are respectively connected. In the ROM 8 described above, a multi-stage membership function is prepared,
In the case of a membership function that matches the content of the change command from the operation unit 6 or the external input means 10, the membership function can be changed by itself. Therefore, the ROM 8 also has a function as an inference rule storage unit that associates the relationship between the state quantity and the operation quantity as a qualitative rule.

The RAM 9 also has a function as a function storage means for expressing the state quantity and the operation quantity by at least one membership function by the input from the external input means 10. Further, in the RAM 9, the external input means 1
When the membership function or the data related to the function is changed by the input from 0, the content is stored and the changed content is used as the basic data for the next fuzzy inference. This allows
Even if there is a change command from the external input means 10 and the change content is input, the data related to the original membership function is stored unless the change content is updated. Therefore, even when the correction value for the membership function is input from the external input means 10, if the adjustment is confused and the adjustment is aborted, the original membership function is retained as it is. Processing can be performed on the original membership function.

The CPU 2 detects the toner density at the time n corresponding to the current state amount with respect to the proper value of the toner density,
The supply time corresponding to the operation amount is calculated by fuzzy reasoning corresponding to the difference.

FIG. 2 is a flow chart for explaining the outline of fuzzy inference, and the following procedure is executed.

(1) Setting of control purpose / variable (2) Formulation of control rule and fuzzy label (3) Calculation of output result The following is a description of each procedure. (1)
In this procedure, in the case of the present embodiment, the purpose is to maintain the toner concentration at the proper value by changing the toner replenishment time, and the difference (change amount) between the toner concentration at this stage and the proper value is a problem. Therefore, this change amount is obtained as the current state amount. In the control, this value is input, and it is set whether to lengthen or shorten the toner replenishment time that affects the toner density at this stage.

In the procedure of (2), the control rule (base rule) corresponding to the inference rule is replaced except for the case where the toner density difference corresponding to the input matches the aptitude value. (Base rule 1) (Antecedent part proposition) If "toner density is" slightly lower "than the aptitude value", then (consequent part proposition) "Make it slightly thicker" (Base rule 2) (Antecedent proposition) " If the toner density is "slightly higher than the aptitude value", then (the consequent part proposition) "Make it slightly thin". Find the membership function (μ _n (x)). However, x means an input value, and μ _n means a concept n (in this case, the toner density is low and the toner density is high). It should be noted that n means that a plurality of antecedent part propositions can be taken.

FIG. 3 shows the above-mentioned membership function, and the vertical axis shows the degree of agreement of the antecedent part proposition with the control rule. In this case, the fuzzy label is replaced with the concept of "negative" used in normal fuzzy inference, except for the case where it matches the aptitude value. Instead of the concept, the toner density is set to "slightly high".

Further, the fuzzy label is set as "slightly darkened" and "slightly thinned" from the membership function regarding the change amount, except when the fuzzy label matches the aptitude value.

In the procedure of (3), the degree of conformity between the toner density change amount at this stage and the antecedent part proposition is obtained, and when the input toner density change amount and the rule match, the rule is activated. Then, the consequent part proposition of the rule is derived as a conclusion (the operation amount for setting the toner replenishment time).

The consequent part proposition is output in height, and the center of gravity of the area obtained by the logical sum of the outputs of the consequent part proposition in each rule is obtained by the defuzzification operation processing by the head cut method (Min method). And output.

FIG. 4 shows a case where the toner concentration is 40% with respect to the aptitude value in the fuzzy inference shown in FIG. 2 in this embodiment. In FIG. After obtaining the divisional proposition, the conclusion of the divisional proposition is obtained as the centroid of the area by defuzzification operation. In this case, the conclusion (manipulation amount) from the consequent proposition is 0.6 s.
ec.

The operation amount obtained by the above procedure is output as the drive time of the drive motor, and the toner is replenished according to the output. As a result, the toner concentration comes close to the appropriate value, but the control for that is used as the input of the fuzzy inference executed when the next current state amount is detected by the operation amount obtained by the above procedure.

On the other hand, the membership function used for the above fuzzy inference becomes enormous when it is made to correspond to the input value as the parameter. It is physically difficult for the control unit 1 itself to store such a huge amount of input values. Therefore, in this embodiment, the external input means 1
0 allows the above input values to be stored, and
You can change the membership function above.

That is, a membership function prepared in advance is registered in the external input means 10, and the ROM 8
If the membership function in the above is not applicable, new contents are output to the RAM 9 equipped on the copier side, and the operation amount concluded from the consequent part proposition based on the registered new membership function. Is selected and set. In RAM9, new contents are input,
The original membership function and the data related thereto are stored and held until there is a command to update the contents, and if the contents change from the external input means 10 is interrupted, It is possible to change the content again based on the membership function.

The membership function registered in the external input means 10 has a change pattern set in advance stepwise, and in the case of the present embodiment, "increase toner density",
1 to 5 for both propositions of "reducing toner density"
There are several levels available. The contents of this stepwise membership function are different from those registered in the ROM 8 included in the control unit 1.

The external input means 10 is the RO of the controller 1 in advance.
It is used not only when the toner replenishment time is corrected by using the membership function registered in M8, but also when the toner replenishment time is set by using a content different from the membership function. .. In other words, by adjusting the toner replenishment time at the current stage, if you want to change the resulting toner concentration based on the experience of an operator such as a service person, the membership prepared by the external input means itself. The function is selected and its contents are displayed on the display. In this case,
Whether or not there is a change is determined in the process execution process by the CPU 2 provided on the control unit 1 side.

Since the present embodiment has the above configuration,
The operation of the controller 1 will now be described with reference to the flowchart shown in FIG.

In FIG. 5, the control unit 1 performs an interrupt process at every predetermined time, and fuzzy inference is executed in the interrupt process.

In the membership function changing process, it is judged whether or not the membership function is changed (S1). If there is a change, the membership function or operation used in the fuzzy inference being executed at this stage is performed. The control data such as the amount can be transmitted to the external input means 10, and the content of the data can be confirmed on the external input means 10 side (S2). A command to change the membership function can also be issued on the operation unit 6.

By transmitting the data at the current stage to the external input means 10, it is possible to confirm the contents to be changed and the contents at the current stage, and if they match, the purpose is to reset the data. The waste of doing can be omitted.

When the data is transmitted in step S2, it is judged whether or not the received data is different from the contents used at the present stage depending on whether or not the received data exists (S3). It is determined whether or not the reception is completed (S4).

When the reception is not completed, the content of the data to be received is stored in the RAM 9, and when the update command is transmitted, the content is changed and used as the data at the next fuzzy inference. If the change process is interrupted before the update command is transmitted, the RAM 9 is kept in the original membership function. In this case, R of the control unit 1
When the content of the membership function registered in the OM 8 matches the content to be changed, the membership function is selected and changed to the membership function of the table.

On the other hand, when the membership function is changed by the external input means 10, the processing shown in FIG. 6 is executed.

In FIG. 6, the connection with the external input means 10 is confirmed (S10), and it is judged whether or not there is received data such as a membership function or control data from the connected copying machine (S11).

If there is received data, the data is normalized and made easy to see, and is displayed on the display (S12).

If the image forming process based on the received data is good, the operation of the external input means ends (S1).
3) If it is determined that the image forming process using the data is not appropriate, especially if the image density is not appropriate, it is determined whether the data change is necessary after the display process of the received data (S14). In this case, the external input means 10
The membership function is modified, but this modification modifies the input corresponding to the base space of the membership function.
At this time, it is also possible to input the data value of the stepwise membership function prepared in advance without changing the above input.

When data is changed, the external input means 1
Change data of the membership function is transmitted from 0 to the control unit 1 of the copying machine (S15).

According to the present embodiment, since the external input means 10 can transmit a larger amount of change content than the membership function prepared in advance in the control section 1, the configuration of the storage means in the control section 1 is possible. Can be simple.

[0049]

As described above, according to the first to fifth aspects of the present invention, the membership function for fuzzy reasoning stored in the control unit used in the image forming apparatus is input to the external input means or the operation amount. Since it can be changed independently by the control means, it is possible to set proper control for the control target for each image forming apparatus. As a result, the change of the control content related to the controlled object can be made to correspond to the advanced and fine adjustment by the experienced person or the designer, so that the best control condition can be obtained by each image forming apparatus. .

In particular, according to the first aspect of the invention, since the control contents can be changed by the external input means, the change contents can be set in advance in the control unit in the image forming apparatus by the storage amount capable of coping with the change contents. Therefore, it is possible to prevent an increase in the capacity of the storage medium and the occurrence of communication trouble. Moreover, since only the correction value for the original membership function is changed, even if the adjustment is confused and the change is interrupted, the original value can be restored, so the data related to the membership function may be destroyed. It is possible to prevent such a situation. When the readjustment is performed again, since the original membership function may be used as a reference, it is possible to save the trouble of re-registering the membership function.

According to the second aspect of the invention, since the object to be changed by the external input means is the correction value of the membership function itself, the data of the membership function is changed unlike the change pattern prepared in advance. Therefore, it becomes possible to reflect the control judgment of each image forming apparatus based on abundant experience of service personnel and designers. This allows finer control.

According to the third aspect of the invention, since the change pattern can be set in advance in advance, it is only necessary to arbitrarily select the pattern, and even a serviceman who lacks experience can individually The change control operation for the image forming apparatus can be easily performed.

According to the fourth aspect of the present invention, since the data inside the image forming apparatus related to the change of the membership function can be displayed by the external input means, the standard for changing the control content can be easily set. Can be confirmed in
It is possible to shorten the time spent for changes and changes due to incorrect contents.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of a control unit used in an image forming apparatus according to the present invention.

FIG. 2 is a flowchart for explaining fuzzy inference executed by a control unit shown in FIG.

FIG. 3 is a diagram showing a membership function used in the control unit shown in FIG.

FIG. 4 is a diagram for explaining an example of fuzzy reasoning executed in a control unit shown in FIG.

5 is a flowchart for explaining the operation of the control unit shown in FIG.

FIG. 6 is a flowchart for explaining an operation executed by an external input unit connected to the control unit shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control part 2 CPU which is arithmetic control means 5 Sensor which is state quantity detection means 6 Operation part which is operation amount control means 8 ROM which is storage means 9 RAM which is information storage means

Claims (4)

[Claims] 1. A controlled amount detecting means for detecting a controlled amount of a controlled object, a state amount detecting means for detecting a state amount related to the controlled amount detected by the controlled amount detecting means, and the above control. An operation amount control means having a function of inputting or displaying an operation amount related to control of an object and a control program for controlling the controlled amount are stored, and the relationship between the state amount and the operation amount is qualitatively stored. Storage means for storing inference rules associated with each other as rules, and information storage means for storing the operation amount and the operation data and also storing data relating to the inference rules input from external input means connected outside the apparatus. , An arithmetic control processing means for executing arithmetic control processing by the control program is provided in an apparatus having a controlled object, and at least one of the state quantity and the operation quantity is provided. In an image forming apparatus having a function storage means expressed by a membership function and controlled by fuzzy inference, the change of the membership function used by the external input means is based on the original membership function as a reference value, An image forming apparatus characterized in that only a value for correcting it is changed. 2. The image forming apparatus according to claim 1, wherein the parameter changed by the external input means is the correction value itself of the membership function. 3. The image forming apparatus according to claim 1, wherein the target of which the input is changed by the external input means is an input value which is changed stepwise in advance. 4. The image forming apparatus according to claim 1, wherein data relating to a membership function for an apparatus having the controlled object is displayed by the input means.