JPH0389369A - Image forming device - Google Patents

Abstract

PURPOSE:To independently control the correction of a delay and to precisely and readily correct a manipulated variable in spite of variance between machines and a secular change by providing a means varying the weight of rules mainly controlling when fuzzy inference is performed. CONSTITUTION:A fuzzy inference means 801 is provided with a means to calculate rules controlling inference results, a means 805 storing the transit sequence of the rules controlling the inference results and a means which weights the rules controlling the inference results and varying them at the time of inference. Consequently, the weight is appropriately varied to cope with the fluctuation of the delay amount of a control system. For state quantities used to control temperatures, for instance, deviation of a current temperature from a target one, a temperature inclination, that is, a temperature change per unit hour and the area of a recording medium passing through a fixing unit per unit hour are adopted; three in all. Consequently, the fluctuation of the delay amount of the control system, which steam from variance in manufacturing machines and a secular change, can be eliminated to precisely control the delay of the control system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus, and more particularly to a control apparatus for an image forming apparatus that controls a controlled object using fuzzy inference.

[Conventional technology]

Conventionally, control devices for image forming apparatuses have performed formulaic control based on definitive judgments based on state quantities.

For example, for a fixing device in an image forming apparatus, the temperature of the fixing device is generally detected using a heat-sensitive element such as a thermistor, and a heat source such as a heater is controlled at a predetermined temperature level. For example, if the detected temperature is lower than 180°C, the heater is energized (ON) L/, 1
When the detected temperature was higher than 80° C., the heater was turned off.

In addition, various methods have been devised as improvement measures to reduce fluctuations with respect to the target temperature, such as making the heater ON time variable depending on the current temperature.

[Problems to be Solved by the Invention] However, image forming apparatuses such as copying machines generally have large fluctuations due to the environment, and are often governed by an ambiguous relationship C between state quantities and manipulated variables. As the number of devices increases, in most cases it is difficult to formulate control as in the conventional example.

For example, in the temperature control of the fixing device, when the state variables such as room temperature, number of copies, document density, type of recording medium (paper type), and temperature of the fixing device itself change, the toner transferred to the transfer paper is fixed. Although it has been known empirically that the fixing ability varies in a complex manner, it has been difficult to formulate the relationship between these state variables and manipulated variables. / The degree of heat dissipation differs when paper is not passing, and in conventional control that turns off above a certain temperature and turns on below a certain temperature, temperature fluctuations (hereinafter referred to as temperature ripple) occur, so the minimum value of this temperature ripple is It was necessary to set the value to a temperature sufficient for the toner to fix on the transfer paper, and therefore the temperature control setting temperature had to be set higher than the ideal state. There was a problem in that it was necessary to use heat-resistant materials to make up the container.

Therefore, it is conceivable to calculate the manipulated variable by performing fuzzy inference on the ambiguous relationship between the state quantity and the manipulated variable.

By the way, many of the control systems of image forming apparatuses use so-called feedback, which determines the manipulated variable to control the controlled object, detects how the state quantity has changed due to the manipulated variable, and then determines the manipulated variable again. It is a control system, and there are delays in the control system due to responsiveness and stability.

Therefore, it is possible to reflect this delay in the control system in the fuzzy rules or membership functions of fuzzy inference, but this method alone does not allow for detection means or manufacturing variations between the machines to be controlled, changes over time, etc. It is difficult to adequately respond to variations in the amount of delay based on .

The present invention was developed in view of the above points, and its purpose is to eliminate the influence of fluctuations in the amount of delay in the control system due to manufacturing variations between machines, changes over time, etc. The objective is to be able to accurately compensate for system delays.

[Means for Solving the Problems] To this end, the present invention provides a state quantity detection means for detecting the state quantity of a controlled object disposed in a device, a control means for giving a manipulated variable to the controlled object, a state quantity and a manipulated variable. A rule storage means that associates the relationship between the variables as qualitative rules, a function storage means that expresses the state quantity and the manipulated variable as at least one ambiguous set, and a function memory means that expresses the state quantity and the manipulated variable as at least one ambiguous set. an inference means for calculating the degree and inferring the most likely operation amount; a calculation means for calculating a rule governing the inference result; a storage means for storing the transition order of the rule governing the inference result; The present invention is characterized in that it includes weighting means for weighting the next dominant rule when the inference means makes an inference and for changing the weight.

[Function] In the image forming apparatus of the present invention, in the fuzzy inference means,
In addition to providing a means for calculating rules governing the inference result and a means for storing the transition order of the rules governing the inference result, weighting of the next rule that will be dominant in the inference result when inference is performed. By performing this and providing a means for changing this, it is possible to appropriately change the weight to cope with fluctuations in the amount of delay in the control system.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1. Control System (Part 1) FIG. 1 shows an embodiment in which the present invention is applied to a fixing device of an image forming apparatus. Reference numeral 801 is a CPU, which will be described later, which actually performs fuzzy inference. Reference numeral 803 is a ROM, which will be described later. and
Store fuzzy rules and membership functions. 80
Reference numeral 5 denotes a RAM, which will be described later, and is used as a work area when performing fuzzy inference. 807 is an input/output unit (Ilo) which will be described later.
), 813 is an A/D converter that converts an analog signal into a digital signal, 163 is a fixing device that heats the conveyed recording medium such as paper to fix the image, and 163-1 applies heat to the fixing roller. Heater, 163-2 is a thermistor that detects the temperature of the fixing heater, 163-3 is CPU8
This is a control circuit that drives the fixing heater from Kodomosha from 01.

2. Internal configuration of the image forming apparatus FIG. 2 shows an example of the internal configuration of the image forming apparatus according to this embodiment. BEDISTAL has a double-sided processing function that turns the recording medium (paper) over during double-sided recording, and a multi-recording function that records multiple times on the same recording medium.The 300 is a circulating document feeder that automatically feeds documents. A feeding device (hereinafter referred to as RDF), 400 is a T-combining device with a stibble (hereinafter referred to as a stable sorter)
Each of these 200 to 400 devices has a main body of 100
However, they can be used in any combination.

(A) About the main body (100) In the main body 100, 101 is a document table glass on which a document is placed, and 103 is an illumination lamp (exposure lamp) that illuminates the document.
, 105, 107, and 109 are scanning reflection mirrors (scanning mirrors) that change the optical path of the light reflected from the original, respectively;
111 is a lens having focusing and variable magnification functions, 113 is a fourth reflection mirror (scanning mirror) that changes the optical path, 115 is an optical system motor that drives the optical system, 117, 1
19 and 121 are sensors, respectively.

131 is a photosensitive drum, 133 is a main motor that drives the photosensitive drum 131, 135 is a high voltage unit, 137 is a blank exposure unit, 139 is a developing device, 141 is a transfer electric device, 147 is a separation charger, and 145 is a beam-leaning device. be.

151 is the upper cassette, 153 is the lower cassette, 171
1 is a manual paper feed slot, 155 and 157 are paper feed rollers, 1
59 is a registration roller. Further, 161 is a conveyor belt that conveys the recording paper on which an image has been recorded to the fixing side, 163 is a fixing device that fixes the conveyed recording paper by heat fixing, and 1
67 is a senna used for double-sided recording. In the fixing unit, 163-1 is a heater for heating the fixing roller, and 183-2 is a thermistor for temperature detection.

The surface of the photosensitive drum 131 described above is made of a seamless photoconductor using a photoconductor and an electric conductor. The motor 133 starts rotating in the direction of the arrow in the figure. Next, when the predetermined rotation control and potential control processing (preprocessing) of the drum 131 are completed, the original placed on the original platen glass 101 is moved to the first scanning roller 1.
The light reflected from the original is illuminated by an illumination lamp 103 that is integrated with the scanner 05, and the reflected light from the original is transmitted to the first scanning mirror 105, the second scanning mirror 107, the third scanning mirror 109, and the lens 111.
, and a fourth scanning mirror 131 to form an image on the drum 131.

The drum 131 is corona charged by a high pressure unit 135. After that, the image illuminated by the illumination lamp 103 (
The original image) is exposed to slit light, and an electrostatic latent image is formed on the drum 131 using a known Carlson process.

Next, the electrostatic latent image on the photosensitive drum 131 is transferred to a developing device 139.
The toner image is developed by a developing roller 140 and visualized as a toner image, and the toner image is transferred onto a transfer paper by a transfer charger 141 as described later.

That is, the upper cassette 151 or the lower cassette 1
The transfer paper in 53 or the transfer paper set in the manual paper feed port 171 is fed into the main unit by a paper feed roller 155 or 157, and the leading edge of the latent image is aligned with the leading edge of the transfer paper. After that, the transfer charger 141 and the drum 131
The transfer paper is discharged from the main body 100 by passing between the two.

After the transfer, the drum 131 continues to rotate, and its surface is cleaned by a cleaning device 145 composed of a cleaning roller and an elastic blade.

(B) About Bedistal (200) Bedistal 2
0G can be separated from the main body 100, and 2000
It has a deck 201 capable of storing sheets of transfer paper and an intermediate tray 203 for double-sided copying. Also, the 200
The lifter 205 of the deck 201 that can accommodate 0 sheets is raised according to the amount of transfer paper so that the transfer paper always comes into contact with the paper feed roller 207.

Further, 211 is a paper ejection flapper for switching the path between the double-sided recording side or multiplex recording side and the ejection side path; 213;
215 is a conveyance path of the delivery belt, and 217 is an intermediate tray weight for holding down the transfer paper. Paper discharge flapper 211. The transfer paper that has passed through the transport paths 213 and 215 is turned over and stored in the intermediate tray 203 for double-sided copying. Reference numeral 219 denotes a multiple flapper that switches the path between double-sided recording and multiplex recording, and is disposed between the conveyance paths 213 and 215, and rotates upward to guide the transfer paper to the multiplex recording conveyance path 211.
, 223 is a multiple sheet discharge sensor that detects the end of the transfer sheet passing through the multiple flapper 219. A paper feed roller 225 feeds the transfer paper to the drum 131 through a path 227.

229 is a discharge roller that discharges the transfer paper to the outside of the machine.

During double-sided recording (double-sided copying) or multiple recording 8 (multiple copying), first raise the paper discharge flapper 211 of the main body 100 to information, and then move the copied transfer paper to the conveyance path 21 of the pedicle 200.
3, 215 and stored in the intermediate tray 203. At this time, the multiple flapper 219 is lowered during double-sided recording and raised during multiple recording.This intermediate tray 203 can store up to 99 sheets of transfer paper, for example.

The transfer paper stored in the intermediate tray 203 is held down by the intermediate tray weight 217.

During the next back-side recording or multiplex recording, the transfer paper stored in the intermediate tray 203 is moved one by one from the bottom to the path 2 by the action of the paper feed roller 225 and the weight 217.
27 to the registration rollers 159 of the main body 100.

(C) RDF (Recirculating Original Feeder) (300) In the RDF 300, 301 is a stacking tray on which a bundle of originals 302 is set. First, in the case of single-sided originals, the half-moon roller 304 and separation roller 303
The originals are separated one by one from the bottom of the document 02, and the separated originals are conveyed from the conveying rollers 305 and the full-surface belt 306 to the exposure position on the platen glass 101 through the bus INII, and are then stopped, after which the copying operation starts. After the copying is completed, the original on the platen gala lot is sent to the bus v1■ by the conveyance large roller 307 through the bus 11■, and is returned to the top surface of the document bundle 302 by the paper ejection roller 308 again.

Reference numeral 309 denotes a recycle lever for detecting document circulation. When the document feed starts, the recycle lever 309 is placed on top of the document stack, and when the documents are rapidly fed one after another and the trailing edge of the final document passes through the recycle lever 309. One circulation of the document is detected by the document falling onto the stacking tray 301 due to its own weight.

Next, for double-sided manuscripts, as mentioned above, once the manuscript is separated, ! After the copying is completed, the leading edge of the document is guided to the bus by switching the drivable switching flapper 310, and the document is conveyed by the transport roller 305 through the bus II and onto the platen glass 101 by the full-surface belt 306. make it stop. That is, the configuration is such that the rotation of the large transport roller 307 causes the document to be reversed along the routes of buses In to ■ to ■.

Also, the document bundle 302 is transferred one sheet at a time to buses I P-II to II.
It is also possible to count the number of originals by conveying them through I~■~V~■ until one cycle is detected by the recycle lever 309.

(D) Stable sorter (collation RA with stable)
(400) The stipple sorter 400 has a fixed non-sorting tray 411 with 20 bins and performs 7 bins.

In the sort mode, the copied sheets are sequentially discharged from the paper feed roller 229 of the main body, enter the conveyance roller 401 of the sorter 400, pass through the conveyance path 403, and are discharged from the discharge roller 405 to each bin of the tray 412. Each time, a bin shift motor (not shown) moves each bin up and down to perform 7 rounds. Further, when the stable mode is selected and the stable signal is manually input from the main body 100, the stable device 420 stipples the sheets in each bin while moving the sheets one bin at a time using the bin shift motor.
aple) and go.

34 operation panels FIG. 3 shows an example of the arrangement of the operation panels provided on the main body 100 described above. The operation panel has a key group 600 and a display group 700 as described below.

(A) Regarding the key group (600) In Fig. 3, 601 is the asterisk (◆) key, which is used when the operator (user) is in the setting mode to set the binding alternative and the size of the original frame eraser. . 60
Reference numeral 6 denotes an all reset key, which is pressed to return to the standard mode, and this key 602 is also pressed to return to the standard mode from the auto-shutoff state.

605 is a copy start key (copy start key);
Pressed to start copying.

A clear/stop key 604 functions as a clear key during standby and as a stop key during copy recording. This clear key is also used to cancel the set number of copies. Further, the stop key is pressed to interrupt continuous copying, and the copying operation is stopped after the copying at the time when the stop key is pressed is completed.

Numeric keys 603 are pressed to set the number of copies. It is also used to set the * (asterisk) mode. A memory key 619 allows the user to register frequently used modes. Here, Ml
You can register four modes: ~M4.

Copy density keys 611 and 612 are pressed when manually adjusting the copy density. 613 is the ^E key, which is pressed when automatically adjusting the copy density according to the density of the original, or when canceling AE (automatic density adjustment) and switching the density adjustment to manual (manual). . aQ7 is a cassette selection key, and upper end cassette 1
51, interruption cassette 153, lower paper deck 201
Pressed when selecting. Also, when a document is on the RDF300, the company uses this key 607 to access the APS (
Automatic paper cassette selection) can be selected. When APS is selected, a cassette of the same size as the original is automatically selected.

Reference numeral 610 is a same size key, which is pressed when making a same size (original size) copy. Reference numeral 616 denotes an auto-magnification key, which is pressed when specifying automatic reduction or enlargement of the specified transfer paper size (as well as the original image).

A double-sided key 626 is pressed when making a double-sided copy from a single-sided original, a double-sided copy from a double-sided original, or a single-sided copy from a double-sided original. 625 is a binding margin key, which can create a binding margin of a specified length on the left side of the transfer paper. 624 is a photo key, which is pressed when copying a photo original.

Reference numeral 623 is a multiple key, which is pressed when creating images (bottom) on the same side of transfer paper from two originals.

Reference numeral 620 denotes a document frame erase key, which is pressed by the user when erasing the frame of a standard size document. At this time, the size of the document is set using the asterisk key 801. Reference numeral 621 denotes a sheet frame erase key, which is pressed to erase the frame of the document according to the cassette size.

Reference numeral 614 is a paper ejecting method selection key for selecting the ejecting method of stapling, sorting, and group.If a stabilizer is connected to store the paper after recording, it is used to select the stable mode and sort mode, or to cancel the selected mode. If a sorting tray (sorter) is connected, you can select the sort mode and group mode, or cancel the selection mode.

Reference numeral 615 is a paper folding selection key, which is used to select either two-fold, which folds recorded paper of A3 or B4 size into a Z-shaped cross section, or half-fold, which folds recorded paper of A3 or B4 size in half. You can cancel the selection.

(B) Display group (700) In Figure 1J3, 701 is an LCD (701) that displays information regarding copying.
It is a liquid crystal (liquid crystal) type message display, for example, one character is made up of 5 x 7 dots, and it displays messages and fixed magnification keys 608, 809, . Same size key 810. Zoom key 6
The copy magnification set at 17,818 can be displayed for 40 characters. This display 701 is a transflective liquid crystal,
Two colors are used for the backlight, the green backlight is normally lit, and the orange backlight is lit when there is an abnormality or when copying is not possible.

Reference numeral 706 denotes a 1:1 display, which lights up when 1:1 copying is selected. A color developer display 703 displays the number of copies or a self-diagnosis code.

705 is a used cassette indicator, which indicates the upper cassette 15.
1. Middle cassette 153. Displays whether any of the lower cassettes 201 is selected.

704 is an AE display, and the AE key 613
Lights up when (automatic density adjustment) is selected.

A preheating indicator 709 lights up when a double-sided copy is made from a double-sided original or a double-sided copy is made from a single-sided original.

Note that when using the RDF300 in standard mode, the settings are 1 copy, density AE mode, automatic paper selection, same size, and 1-sided copying from a 1-sided original.

When the RDF300 is not in use, the standard mode is set to 1 copy, manual density mode, same size, and 1-sided copying from a 1-sided original. The difference between when the RDF 300 is used and when it is not used is determined by whether or not a document is set on the RDF 300.

71G is a power lamp, which lights up when a power switch (not shown) is turned on.

4. Control System (Part 2) FIG. 4 shows a configuration example of the control device 800 of the embodiment shown in FIG. 2. In FIG. 4, reference numeral 801 is a central processing unit (CPtl) that performs arithmetic control for executing control to be described later, and for example, a 16-bit microcomputer such as V2O manufactured by NEC Corporation can be used. 803 is a read-only memory (ROM) in which the control procedure (control program) according to this embodiment is stored in advance;
801 controls each component device stored in this ROM 803. Reference numeral 805 denotes a random access memory (RAM) which is a main storage device used for storing input data and as a working storage area.

807 is an output signal transfer interface (I
809 is an input signal transfer interface that inputs input signals from the image tip sensor 121 and the like and sends them to the CPO 301, and 811 is an interface that controls input and output of the key group 600 and the display group 700. For these interfaces 807, 809, and 811, for example, an input/output circuit port μPD8255 manufactured by NEC Corporation is used.

Note that the display group 700 is each display device shown in FIG. 3, and uses, for example, an LED (light emitting diode) or an LCD (liquid crystal display). Further, the key group 600 is each key shown in FIG. 3, and is configured so that the CPU 801 can know which key has been pressed using a known key matrix. Further, 1630 is a fixing system unit, which includes each section 183, 807, 813, etc. in FIG.

(The following is a margin) 5. Operation Example Next, a temperature control operation when the present invention is applied to a fixing device C of an image forming apparatus will be described as an example. The state quantities used in temperature control include, for example: ■ Temperature deviation of the current temperature from the target temperature ■ Temperature gradient, which is the amount of temperature change per unit time ■ Area of the recording medium passing through the fixing device per unit time (after the paper surface) ) are used.

As a manipulated variable when performing temperature control, ■Heater 163-1 ON time Use.

FIG. 5 shows a fuzzy set called the membership of the state quantities and manipulated variables described above. Each of the temperature deviation, the temperature gradient, the paper surface, and the heater ON time belongs to at least one of several sets determined by the amount and the degree to which the amount belongs (degree of conformity). In the case of temperature deviation, temperature gradient, and heater ON time, 1) NB (Negative Big) is a negative value and has a large absolute value.

2) NS (Negative Small) A negative value with a small absolute value.

3) ZO (Zero) Near O.

4) PS (Posltive Small) A positive value with a small absolute value.

5) Pa (Positive Small) A positive value with a large absolute value.

shall be.

Also, regarding the back of the paper, 1) SM (SMALL) small area 2) ME (MEDIIJM) medium size 3) LA (LARGE) large area shall be.

The fitness for each set is expressed as a value from O to 1. In Fig. 5, (a) is the membership function of temperature deviation,
The same < (b) is the membership function of the temperature gradient, the same < (
C) is the membership function of the paper sheet passing through the fixing device per unit time, and (d) is the membership function of the heater ON time.0 For example, in the case of temperature deviation, ZO (a) in the figure is
For example, when the temperature deviation is 0° C., it is 1.0 if it belongs to the set zO. Also, for example, when the temperature deviation is 1.5°C (or -1.5°C), it means that the degree of belonging to the set zO and ps (or NS) is 0.5. The same applies to other cases. be.

Next, a method of calculating the heater ON time, which is a manipulated variable, from each state quantity of the temperature deviation, temperature gradient, and paper area by fuzzy reasoning will be described.

For example, the following fuzzy rules are used to determine the heater ON time.

(Rule 1) If Temperature deviation 5 = PBand Temperature gradient + aZO
and Paper area depth ME then Heater ON time = NS (Rule 2) If Temperature deviation = PSand Temperature gradient - ZOan
dPaper area=ME then Heater ON time=20 Such fuzzy rules are appropriately set according to the control target, control environment, etc. FIG. 6 shows an example of fuzzy rules when controlling the fixing device according to this example, where E is the temperature deviation, DE is the temperature gradient, sp is the paper surface area, and H is the heater O.
It is N hours.

First, a conventional basic fuzzy inference method will be explained as a comparison target for this example.

FIG. 7 is an example of calculating the heater ON time by fuzzy reasoning using the above-mentioned (Rule 1) and (Rule 2).

As an example, temperature deviation = X, temperature gradient = y and paper score =
Consider the case of 2.

In (Rule 1), from the membership function of temperature deviation,
It is included in the set of PB with a degree of μ8 for the input The center of ME is aligned with respect to Z at a degree of μ8.

First, take the minimum value (logical product) of μ8, μ, and μ8 according to the antecedent part of the above rule, and set that value (μ, in this case) as the degree to which the condition part of rule 1 is satisfied (degree of fitness)0 Next, if we perform a logical AND operation (MIN operation) between this degree and the membership function NS of the heater ON time (in order to reflect this degree in the fuzzy set of the consequent part), the inference result is S
Obtain the trapezoid defined by the three sides excluding the base indicated by the shaded area. (Rule 2), the same calculation is performed and T
The inference result of the fuzzy set defined by the three sides of the trapezoid shown by the shaded area excluding the base is obtained. Then, the set of S and T
By taking the maximum value (logical product) with the set of , a new fuzzy set indicated by the sides excluding the base of the hatched part U is obtained as the final inference result. Then, the value obtained by calculating the center of gravity of this set is used to turn on the heater obtained by fuzzy reasoning.
Set the time. The same thing is done for the fuzzy rule shown in FIG.

Here, a means for calculating rules governing the inference results will be described.

To explain using the example in Figure 7, the above-mentioned MIN calculation is performed on the inputs x, y, and z, and the trapezoid shown by the shaded part of S is found.The area of this trapezoid is calculated as the degree of dominance (rule 1) Compare the degrees of dominance (area of the trapezoid) obtained from each rule, and choose the largest one as the rule that dominates the inference results. In this example, (Rule 1) is the dominant rule.

Next, we will discuss the transition order of rules governing the inference results.

Figure 8 shows the relationship between the fuser temperature and time, and Figure 9 shows the relationship between the fuser temperature and time.
■ to ■ in these figures, which show the relationship between temperature deviation and temperature gradient at the characteristic points in the figures, are corresponding points, respectively. In this way, the feature points transition according to a certain rule. Then, at each feature point, rules including each feature become dominant.

In other words, at point ■, (if temperature gradient = PBand
The rule including the antecedent part ``temperature gradient = zO'' becomes dominant. The transition order of this dominant rule is
is memorized.

In this example, the transition order of the dominant rule is considered, and when inference is performed, the next dominant rule is weighted and the weight is changed.
To always accurately correct delay in a control system regardless of variation in delay amount (for example, variation in delay amount of a thermistor due to aging, etc.). The weighting is performed by the CPt 1801 based on weighting data stored in the RAM 805.

FIG. 10 relates to this embodiment and is an example of performing fuzzy inference by changing the weight of the next dominant rule.

The dominant rule for the input values x, y, and z in Figure 10 is (Rule A), which corresponds to ■ in Figure 9, so the next dominant rule is (Rule B). I know it's a rule. Therefore, the heater ON time T found from (Rule B) is multiplied by a certain correction coefficient to obtain To, and the next center of gravity calculation is performed to determine the heater ON time.

The initial value of this correction coefficient is determined at the time of inspection or factory shipment, and can be stored in the ROM 803 or the RAM 805 backed up by a battery, for example. After that, the correction coefficient is changed according to the function shown in FIG. 11 in order to reflect the change in the delay amount due to the change in the thermistor etc. over time. This calculation is performed by the CPO 301.
The function in FIG. 11 is a ratio to the initial setting value. That is, for example, a means for integrating the heater energization time is provided, and a look-up table of the integrated value and the ratio is provided in the ROM, etc., and the CPtl 801 refers to this and uses the ratio as the initial value of the correction coefficient (!!). All you have to do is take advantage of it.

6. Control Means Next, the control procedure of this embodiment will be explained with reference to FIG. This is an example of a control procedure that is activated by an interrupt every predetermined time (Logs in this example).

First, heater ON time 1 (
1 is a parameter used to regulate the heater energization time, and in this example, the unit is 10 m5), t is 0.
0'' (step! 2-1), and if it is ``O'', calls a fuzzy inference subroutine that sets the heater ON time t by fuzzy inference, and then returns.

On the other hand, if the judgment in step 12-1 is negative, the heater is turned on.
Determine whether time t is positive or negative (step 12-3), and if it is positive, subtract "1" from the value of t (step 12-4).
Then, it is determined whether the heater ON time t is "01" (step 12-5). If it is "0", the fuzzy inference subroutine (step 12-7) is called, and then the process returns.- If the judgment in step 12-5 is negative, turn on the heater and step 12-6
), return.

If it is determined in step 12-3 that the heater ON time t is negative, the company adds "1" to the value of t (step 12-8).
Then, it is determined whether the heater ON time t is "O" or not (step 12-9). If it is "O", the fuzzy inference subroutine (12-7) is called, and then the process returns. Conversely, if the determination in step 12-9 is negative, the heater is turned off (step 12-10) and the process returns.

Next, an example of the fuzzy inference subroutine operation procedure will be explained with reference to the procedure shown in FIG.

First, the temperature of the fixing roller is measured by the thermistor 163-2 (Step 13-1), the deviation of the current temperature from the target temperature and the temperature gradient, which is the temperature change per unit time, are calculated (Step 13-2). , the paper area is calculated from the paper size specified by the user or the RDF 300 (step 13-3).

Then, for all the fuzzy rules shown in Figure 6,
Using the method described above, calculate the degree of belonging to the fuzzy set of the manipulated variable from the degree of belonging to the fuzzy set of the state quantity according to each fuzzy rule (Step 13-4.13-5), and calculate the maximum value of the set belonging to each rule. 13-6)
, calculate and determine the current optimal correction coefficient from the ratio described in connection with FIG. 11, and then multiply by the consequent part C correction coefficient of the aforementioned dominant rule (step 13-7) By determining the center of gravity, the most likely operation amount is calculated (step 13-8) and set as the heater ON time t (step 13-9).

As mentioned above, the heater ON time t is used when controlling the heater ON time in the 10m5 interrupt, and the lhs
Set the value in units of .

7. Other Embodiments Below, another embodiment of means for weighting the next dominant rule when performing fuzzy inference and changing the weight will be described.

When performing the full fuzzy inference shown in FIG. 6, in this example, a certain value is added or subtracted from the consequent of the next dominant rule. Here, it is assumed that addition is performed in a direction that suppresses the influence of delay, that is, a constant value.

This added value can be stored in the ROM 803 or the RAM 805 backed up by a battery.
The initial value is determined at the time of inspection or factory shipment. After that, in order to reflect changes in the amount of delay due to changes in the thermistor, etc. over time, ′! The added value is changed according to the function shown in Figure J14. This calculation can be performed by the PU 801 in the same manner as in the first embodiment. The function in Figure 14 is
This is the ratio to the initial setting value.

Next, the control procedure of this embodiment will be explained with reference to FIG. This is an example of a control procedure that is activated by an interrupt every predetermined time (for example, 10m5).

First, it is determined whether t is 10" according to the heater ON time t set in the conventional FIG. 16 (step 15-1).
), @O”, calls a fuzzy inference subroutine that sets the heater ON time t by fuzzy inference,
Then return.

On the other hand, if the judgment in step 15-1 is negative, the heater is turned on.
Determine whether time t is positive or negative (step 15-3), and if positive, subtract 1 from the value of t (step 15-4).
Then, it is determined whether the heater ON time t is "0" (step 15-5). If "O" here, the fuzzy inference subroutine (step 15-7) is called, and then the process returns. On the other hand, if the judgment in step 15-5 is negative, the company turns on the heater (step 15-8).
, return.

If the heater ON time t is negative in Step E5-3, add "1" to the value of t (Step 15-8).
, it is determined whether the subsequent heater ON time t is "O" or not (step 15-9), and if @01, the fuzzy inference subroutine (step 15-7) is called and then the process returns. Conversely, if the determination in step 15-9 is negative, the heater is turned off (step 15-10) and the process returns.

Next, an example of the fuzzy inference subroutine operating procedure according to this example will be explained with reference to the procedure shown in FIG.

First, the temperature of the fixing roller is measured by the thermistor 163-2 (step 1B-1), and the deviation of the current temperature from the target temperature and the temperature gradient, which is the temperature change per unit time, are calculated (step 16-2). Also, the paper area is calculated from the paper size specified by the user or the RDF 300 (step 1B-3).

Then, for all the fuzzy rules shown in Figure 6,
Using the method described above, calculate the degree of belonging to the fuzzy set of the manipulated variable from the degree of belonging to the fuzzy set of the state quantity according to each fuzzy rule (step 16-4.16-5), calculate the maximum value of the set belonging to each rule, (Step 16-6)
, obtain the optimal addition value by similarly performing step 13-7 above, then add a certain value to the consequent of the aforementioned dominant rule (step 16-7), and calculate the most by determining the center of gravity. Calculate the most likely operation amount Step 16-8
) is set as the heater ON time t. (Step 1
li-9).

The heater ON time t is also used in this example when controlling the heater ON time in the 10m5 interrupt, and is set to a value in units of 1h+s.

8. Others In the above embodiments, the control target is a fixing means, but other devices such as a charging means, an exposure means, a transfer means, a recording medium feeding means, a conveying means, an image forming mode setting means, etc. Similar control can be applied to each of the means within.

For example, the state quantity in the transfer means can be room temperature, humidity, atmospheric pressure, etc., and the operation quantity can be the current applied during charging.

Further, as the state quantity in the exposure means, the potential of the photoreceptor, the developing bias, etc. can be taken, and the operating quantity can be taken as the lighting voltage of the exposure lamp.

The state quantity in the conveyance means may be the conveyance speed, conveyance speed gradient, humidity, etc., and the operation variable may be the conveyance speed control voltage.

Further, in this embodiment, a fixing device of an electrophotographic copying machine is used as an example, but the image forming apparatus of the present invention is not necessarily limited to an electrophotographic copying machine, but can also be applied to an inkjet printer, a thermal printer, etc. 0 For example, the fixing device in this embodiment is a heater! I took the l1II Go as an example,
If a means for drying printed ink is used in an inkjet printer, this can also be called a fixing device in a broad sense.Furthermore, the present invention is applicable to means other than the fixing device, such as optical system drive motor control.

Further, the above-mentioned fuzzy inference algorithm is just an example, and the algorithm may be modified. For example, instead of taking the center of gravity of the maximum area when combining multiple rules,
The value on the horizontal axis relative to the maximum value on the vertical axis may be used as the inference result, and the number and content of fuzzy rules can also be modified based on empirical rules.

In addition, instead of storing fuzzy sets and rules independently in RAM or ROM and performing fuzzy inference calculations during control, the results of inferences made in advance for all input combinations of state quantities are stored in a lookup table. (R
OM), it is possible to easily obtain an output according to the input of the state quantity.

In addition, the multiplication by the correction coefficient is not performed by the CPO 301;
A multiplication circuit may be provided separately.

As explained above, according to the above embodiment of the present invention, an image forming apparatus, which has conventionally been subjected to fixed control in response to changes in the environment, can be efficiently controlled by giving control that takes complex factors into consideration. image formation processing can be performed. In addition, since the control amount is determined based on multiple parameters, even if there is an error in some of the input data,
! It is possible to prevent a large amount of dJ from occurring.

[Effects of the Invention] As described above, according to the present invention, the weight of the next dominant rule is changed when performing fuzzy inference, which eliminates manufacturing variations and changes over time of the detection means and $Ja object. By providing a dedicated means to compensate for fluctuations in the amount of delay in the control system caused by Can be corrected. As a result, power consumption, paper jams, damage, etc. of the image forming device can be kept to a minimum at all times, and further process control can be performed optimally, resulting in improved image quality and improved image formation. can significantly improve reliability.

[Brief explanation of drawings]

FIG. 1 is a basic block diagram showing an example of the configuration of a control a II system when the present invention is applied to a fixing device according to an embodiment of the present invention, and FIG. 2 is a general block diagram of an image forming apparatus according to the present embodiment. 3 is a cross-sectional view showing an example of the internal configuration; FIG. 3 is a plan view showing an example of the external configuration of the operation panel of the embodiment; FIG. is a diagram for explaining membership functions that can be adopted in this embodiment, FIG. 6 is an explanatory diagram showing fuzzy rules that can be applied to this embodiment, and FIG. 7 is a diagram for explaining a conventional fuzzy inference method. Figure 's8 is a diagram showing the relationship between the temperature and time of the fuser, which is the target of flJm in this embodiment, and Figure 9 is a diagram showing the temperature deviation and temperature gradient at each characteristic point in Figure 8. Figure 10 is an explanatory diagram for explaining the fuzzy inference method applied in this example, Figure 11 is a diagram showing the ratio of the correction coefficient to the initial setting value according to this example, FIG. 12 is a flowchart showing an example of a control procedure for a controlled object (heater) according to this embodiment, FIG. 13 is a flowchart showing an example of a fuzzy inference procedure according to this embodiment, and FIG. 14 is a flowchart showing an example of a fuzzy inference procedure according to this embodiment. A diagram showing the ratio of the correction value to the initial setting value according to the second embodiment, FIG. 15 is a controlled object (heater) according to the second embodiment
FIG. 16 is a flowchart showing an example of the fuzzy inference procedure according to the second embodiment. DESCRIPTION OF SYMBOLS 100... Image forming apparatus main body, 163... Fixing device, 163-1... Heater, 163-2... Thermistor, 163-3... Drive circuit, 200... Bedistal, 300...・RDF. 400... staple sorter, 600... key group, 700... display group, 801-CPU. 803...ROM. 805...RAM. Membership No. 5 Autumn Figure Fu Ding Jiime Brother 2 Show 1 No 6 Friend La Equipment - 1 Time Seki 1 8 Temperature Deviation, Each 5 Bamboo 4 Fragrance, JcjL Lun'e Eul's bottom slope Figure 9 Nenan'! (Ice-like Ne IJspH turtle (legs straight 1 = Dacho tQ Figure 11 10m5 Book i') Included flow 'r〒-) Figure 12 Heater energization time It's the first time I've been in prison for a while.
Figure 4 ioms zero tree 8 sho book diagram 15

Claims (1)

[Scope of Claims] 1) A state quantity detection means for detecting a state quantity of a controlled object disposed in an apparatus, a control means for giving a manipulated variable to the controlled object, and a method for qualitatively determining the relationship between the state quantity and the manipulated variable. rule storage means for relating the state quantity and the manipulated variable as a set of rules; function storage means for expressing the state quantity and the manipulated variable as at least one ambiguous set; an inference means for calculating the degree and inferring the most likely operation amount; a calculation means for calculating a rule governing the inference result; a storage means for storing a transition order of the rule governing the inference result; and 2) the device is a device that forms a latent image on a photoreceptor, visualizes it with a developing device, and transfers the visible image onto a transfer paper, and the control target includes a charging device, an exposing device, a developing device, 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is at least one of a transfer means, a recording medium feeding means, a recording medium conveying means, a fixing means, and an image forming mode setting means. 3) The image forming apparatus according to claim 1, wherein the calculation means selects the rule having the greatest influence from the consequent part of the rule. 4) The image forming apparatus according to claim 1, wherein the weighting means multiplies the consequent part of the rule by a predetermined coefficient. 5) The image forming apparatus according to claim 4, wherein the coefficients follow a predetermined qualitative rule. 6) The image forming apparatus according to claim 1, wherein the weighting means adds or subtracts a predetermined value to a consequent part of the rule. 7) The image forming apparatus according to claim 6, wherein the value follows a predetermined qualitative rule.