JPH04346366A - image forming device - Google Patents

Abstract

PURPOSE:To prevent rear-copying of an image when an original with an image on both sides is copied. CONSTITUTION:This device is provided with an AE sensor 815 for measuring the concentration of an original, a paper thickness sensor 900 for detecting the paper thickness of the original, a ROM 803, in which membership functions and inference rules, and IC cards 901, etc., are stored, in addition to a CPU 801 for executing automatic concentration control. The CPU 801 judges to which member the original belongs by comparing the output values from the sensors 815 and 900 with the membership functions and, based on the judged results, the amount of light from a halogen lamp 103 with high possibility of preventing rear-copying is set by fazzy inference according to the inference rules. With the set value, the amount of light can be controlled.

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 such as a copying machine or a facsimile machine, and more particularly to an automatic density control technique using fuzzy reasoning.

0002

[Prior Art] Conventionally, image forming apparatuses such as copying machines and facsimile machines have not performed density control that takes into account show-through of double-sided originals, and automatic density control (AE) has been used to automatically control copy density.
It was done by the organization. For example, regardless of the paper thickness of the copy document, in AE, the document density is determined only based on the density of the surface to be copied, and the copy density is controlled.

0003

[Problems to be Solved by the Invention] However, in image forming apparatuses such as copying machines, good output results cannot be obtained with conventional density control using only AE as described above, depending on the paper thickness and recording condition of the copy original. There were cases where this was not the case.

For example, even when copying a double-sided original that has images on both sides, the copy density has been controlled using AE by focusing only on the density of the side to be copied of the original. In addition, if the image density on the back side opposite to the side to be copied is high, the output result of image density control using only AE often results in a so-called show-through image in which the image on the back side is reflected. It was there. This is a problem that needs to be solved because the thickness of the original paper is not taken into account in the density control, but image density control can be achieved by formulating the state quantity of the thickness of the original paper itself and the state quantity of the original density. It has been difficult to do so using conventional technology. For these reasons, in the case of double-sided originals, the user had to look at the output result and manually adjust the density to a level that would not cause show-through, which was troublesome in the past.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an image forming apparatus that can prevent image show-through when copying a double-sided original by automatic density adjustment.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a detection means for detecting a paper thickness state quantity corresponding to the paper thickness of a document, and a detection means for detecting a paper thickness state quantity corresponding to the density of the document. a membership function storage means that predetermines membership functions in which the paper thickness state quantity, the density state quantity, and the density control quantity are respectively fuzzy quantities; an inference rule storage means storing an inference rule for associating the membership of the density state quantity with the membership of the density control quantity as a qualitative rule; and the paper thickness state quantity obtained from the detection means. an inference means for executing fuzzy inference based on the concentration state quantity obtained from the measurement means using the membership function and the inference rule to set a target concentration control amount; The present invention is characterized by comprising a control means for adjusting the output image density by a set density control amount.

[0007]Furthermore, the present invention may be characterized in that it comprises a rule changing means that makes it possible to change the inference rules stored in the inference rule storage means.

Furthermore, the rule changing means of the present invention may be an input operation means or an external storage means.

Furthermore, the detection means of the present invention may be a sensor that detects the light transmittance of the document.

0010

According to the present invention, it is possible to prevent image show-through when copying a double-sided original by automatic density adjustment using fuzzy inference.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(1) First Embodiment FIG. 1 shows the basic configuration of a show-through prevention mechanism of an image forming apparatus according to a first embodiment of the present invention. In FIG. 1, 801 is a CPU (central processing unit), which will be described later, and actually executes the fuzzy inference of the present invention. 803 is a ROM (
It is a read-only memory) and stores fuzzy rules and membership functions in advance. 805 is a RAM (Random Access Memory) which will be described later;
801 is used as a work area when performing fuzzy inference. 813 and 814 are A/D (analog-to-digital) converters that convert analog signals to digital signals; 81;
Reference numeral 5 denotes a well-known AE sensor that detects the density of a document when performing automatic density adjustment, and 900 a paper thickness sensor that detects the thickness of paper. As the paper thickness sensor 900, for example, a transmittance sensor or a resistance value sensor is used. 807 is an I/O (input/output interface) which will be described later, and 103-1 is a CP.
This is a control circuit that controls the amount of light from the halogen lamp based on commands from U801. A halogen lamp 103 is a light source that irradiates light onto the original when reading the original. Also, 90
Reference numeral 1 denotes an IC card as an external storage means that allows the inference rules (rules) to be described later to be changed.

FIG. 2 shows the internal configuration of an image forming apparatus to which the present invention is applicable. In FIG. 2, 100 is a copying machine body that has an image reading function and an image recording function, and 200 is a duplex processing function that turns the recording medium (paper) over during double-sided recording, and a duplex function that can perform multiple recordings on the same recording medium. 300 is a circulating document feeder (hereinafter referred to as RDF) that automatically feeds documents; 4
00 is a stapling and collating device (hereinafter referred to as a staple sorter), and each of these devices 200 to 400 can be used in any combination with the main body 100.

A. Main body (100) In the main body 100, reference numeral 101 denotes an original table glass on which the original is placed, 103 an illumination lamp (exposure lamp) for illuminating the original, and 105, 107, and 109 each a scanning lamp for changing the optical path of reflected light from the original. Reflection mirror (scanning mirror), 11
Reference numeral 1 indicates a lens having focusing and variable magnification functions, and reference numeral 113 indicates a fourth reflection mirror (scanning mirror) that changes the optical path. 115 is an optical system motor that drives the optical system, 117, 11
9 and 121 are sensors, respectively.

131 is a photosensitive drum, 113 is a main motor that drives the photosensitive drum 113, 135 is a high pressure unit, 137 is a blank exposure unit, 139 is a developing device, 1
41 is a transfer charger, 147 is a separation charger, and 145
is a cleaning device.

151 is an upper cassette, 153 is a lower cassette, 171 is a manual paper feed slot, 155 and 157 are paper feed rollers, and 159 is a registration roller. Also, 16
1 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 167 is a sensor used for double-sided recording.

The surface of the photosensitive drum 131 described above is made of a seamless photosensitive member using a photoconductor and an electric conductor. By the main motor 133,
Start rotating in the direction of the arrow in this figure. Next, drum 1
When the predetermined rotation control and potential control processing (preprocessing) of 31 is completed, the original placed on the original platen glass 101 is illuminated by the illumination lamp 10 integrated with the first scanning mirror 105.
3, and the reflected light of the original is transmitted to the first scanning mirror 105, the second scanning mirror 107, and the third scanning mirror 109.
, lens 111, and fourth scanning mirror 113, the image is formed on the drum 131.

The drum 131 is corona discharged by a high pressure unit 135. Thereafter, the image (original image) irradiated by the illumination lamp 103 is exposed to the slit, and an electrostatic latent image is formed on the drum 131 using a known NP method.

Next, the electrostatic latent image on the photosensitive drum 131 is
It is developed by the developing roller 140 of the developing device 139 and visualized as a toner image, and the toner image is transferred to the transfer charger 14.
1, the image is transferred onto a transfer paper as described below.

That is, the transfer paper in the upper cassette 151 or the lower cassette 153, or the manual paper feed slot 17
The transfer paper set at No. 1 is fed into the main unit by a paper feed roller 155 or 157, and the leading edge of the latent image and the leading edge of the transfer paper are aligned. Thereafter, by passing the transfer paper between the transfer charger 141 and the drum 131, the main body 1
It will be ejected out of 00.

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. Pedestal (200) The pedestal 200 can be separated from the main body 100,
It has a deck 201 that can accommodate 0 sheets of transfer paper and an intermediate tray 203 for double-sided copying. Also, part 20
The lifter 205 of the deck 201, which can accommodate 00 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 ejecting flapper for switching the path between the double-sided recording side or multi-recording side and the ejecting side path, 213 and 215 are the conveying paths of the conveying belt, and 217 is an intermediate tray weight for holding down the transfer paper. be. Paper ejection flapper 2
11 and the transfer paths 213 and 215 are turned over and stored in the intermediate tray 203 for double-sided copying. A multiple flapper 219 switches between double-sided recording and multiplex recording, and is disposed between the conveyance paths 213 and 215, and guides the transfer paper to the multiplex recording conveyance path 211 by rotating upward. Reference numeral 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 (duplex copying) or multiplex recording (multiple copying), first, the paper ejection flapper 211 of the main body 100
Raise the copied transfer paper upward and place it on the pedestal 20.
0 and stored in the intermediate tray 203 via the transport paths 213 and 215. At this time, when double-sided recording is performed, the multiple flapper 21
9 is lowered, and the multiple flapper 219 is raised during multiple recording. This intermediate tray 203 can store up to 99 sheets of transfer paper, for example. Intermediate tray 203
The transfer paper stored in the tray is held down by the intermediate tray weight 217.

During the next back-side recording or multiplex recording, the transfer sheets stored in the intermediate tray 203 are delivered one by one from the bottom to the main body 100 via the path 227 by the action of the paper feed roller 225 and the weight 217. Registration roller 1
You will be led to 59.

C. RDF (circulating document feeder) (300) RDF3
00, 301 is a stacking tray on which a bundle of originals 302 is set. First, for single-sided originals, the half-moon roller 30
4 and a separation roller 303 from the bottom of the document bundle 302, and the separated documents are transferred to the platen glass 1 by a transport roller 305 and a full-surface belt 306.
The conveyance is stopped after passing through passes I to II to the exposure position 01, and then the copying operation starts. After copying is completed, the original on the platen glass 101 passes through paths III and IV, is sent to paths V and VI by a large transport roller 307, and is returned to the uppermost surface of the original bundle 302 by a discharge roller 308.

Reference numeral 309 is a recycle lever for detecting one circulation of originals. When the original is started to be fed, this recycle lever 309 is placed on top of the stack of originals, and the originals are sequentially fed until the rear end of the last original is recycled. One circulation of the document is detected by the document falling onto the stacking tray 301 due to its own weight when it passes through the lever 309.

Next, in the case of double-sided originals, the thickness of the original is detected by the paper thickness sensor 900 midway through the original transport path, and as described above, the original is guided from passes I and II to pass III, and after copying is completed, the thickness of the original is detected by the paper thickness sensor 900. By switching the possible switching flapper 310, the leading edge of the document is guided to the path, and the document is conveyed through the path II by the conveyance roller 305 and stopped on the platen glass 101 by the full-surface belt 306. That is, the rotation of the large conveyance roller 307 causes passes III to I.
The configuration is such that the document is reversed through routes V to II.

[0029] Also, the document bundle 302 is passed through passes I to I one by one.
By conveying through I~III~IV~V~VI until one cycle is detected by the recycle lever 309,
You can also count the number of originals.

Paper thickness sensor 9 for calculating the above-mentioned paper thickness
00, the paper thickness of the original is measured based on the degree of light transmission when the original is initially fed.

D. Staple sorter (collating device with staple) (4
00) The staple sorter 400 has a fixed non-sort tray 411 with 20 bins in its main body, and performs collation.

In the sort mode, the copied sheets are sequentially discharged from the paper discharge roller 229 of the main body, enter the conveyance roller 401 of the sorter 400, pass through the conveyance path 403, and are delivered from the discharge roller 405 to each bin of the tray 412. Each time a bin is discharged, a bin shift motor (not shown)
Collate by moving each bin up and down. Further, when the stapling mode is selected and a stapling signal is input from the main body 100, the stapling device 420 staples the sheets in each bin while moving the bins one by one using the bin shift motor.

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

E. Key Group (600) In FIG. 3, reference numeral 601 is an asterisk (*) key, which is used by the operator (user) when in a setting mode such as setting the binding margin amount or setting the size of document border eraser. 606 is an all reset key, which is pressed to return to the standard mode. This key 602 is also pressed when returning from the auto-shutoff state to the standard mode.

Reference numeral 605 is a copy start key, which is 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 step key is pressed to interrupt continuous copying. The copying operation stops after the copying at the time when the button 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, four modes, M1 to M2, can be registered.

Copy density keys 611 and 612 are pressed when manually adjusting the copy density. 613 is AE
This key is pressed to automatically adjust the copy density according to the density of the original, or to cancel AE and switch the density adjustment to manual. A cassette selection key 607 is pressed to select the upper cassette 151, the middle cassette 153, and the lower paper deck 201. Further, when a document is placed on the RDF 300, APS (automatic paper cassette selection) can be selected using this key 607. 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 to make a same size (original size) copy. Reference numeral 616 is an auto-magnification key, which is pressed to automatically reduce or enlarge the original image according to the specified transfer paper size.

A double-sided key 626 is pressed to make 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,
You 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. 623 is a multiple key, which is pressed when creating (combining) an image from two originals on the same side of transfer paper.

Reference numeral 620 denotes a document frame erase key, which the user presses when erasing the frame of a standard size document.At this time, the size of the document is set using the asterisk key 601. 62
1 is a sheet frame erase key, which is pressed to erase the frame of a document according to the cassette size.

Reference numeral 614 is a paper discharge method selection key for selecting the paper discharge method of stapling, sorting, and group, and when a stapler is connected to record paper, it selects the staple mode and sort mode, or selects the selected mode. If a sorting tray (sorter) is connected, you can select sort mode and group mode, or cancel the selected mode.

[0043] 615 is a paper fold selection key, A3 and B.
Z-folding involves folding recorded paper of size 4 into a Z-shaped cross section, and A3
You can select or cancel the selection of either folding or half-folding a B4 size recorded paper in half.

F. Display group (700) In FIG. 3, 701 is an LCD (liquid crystal) type message display that displays information regarding copying.
×7 dots make up one character, 40 character message,
The copying magnification set by the fixed magnification keys 608 and 609, the same magnification key 610, and the zoom keys 617 and 618 can be displayed. This display 701 is a transflective liquid crystal display and uses two colors 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.

[0045] Reference numeral 706 is an equal magnification display, which lights up when equal magnification is selected. A color developer display 703 displays the number of copies or a self-diagnosis code. Reference numeral 705 is a used cassette indicator, which displays whether one of the upper cassette 151, middle cassette 153, and lower cassette 201 is selected.

704 is an AE display, and the AE key 61
Lights up when AE is selected by 3. 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.

When using the RDF300 in the standard mode, the settings are 1 copy, density AE mode, automatic paper selection, same size, and 1-sided copying from a 1-sided original. R
In standard mode when DF300 is not in use, the number of copies is 1,
The settings are manual density mode, same size, and single-sided copying from a single-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.

Reference numeral 710 denotes a power lamp, which lights up when a power switch (not shown) is turned on.

G. Control Device (800) FIG. 4 shows a configuration example of the control device 800 of the embodiment of FIG. 2. In FIG. 4, a central processing unit (CPU) 801 is a device that performs calculation control for carrying out the present invention, and for example,
Uses a 6-bit microcontroller computer. A read-only memory (ROM) 803 is a memory in which a control procedure (control program) according to the present invention is stored in advance, and the CPU 801 controls each component device according to the control procedure stored in this ROM 803. Random access memory (RAM) 805 is a memory that is a main storage device used for storing input data and as a work storage area.

[0050] Output signal transfer interface (I/O
) 807 is the CPU 801 for loads such as the main motor 133.
outputs a control signal. Reference numeral 809 represents an input signal transfer interface that inputs input signals from the image tip sensor 121 and the like and sends them to the CPU 801 , and 811 represents an interface that controls input/output between the key group 600 and the display group 700 . These interfaces 807, 809, and 811 are, for example, input/output circuit ports μ manufactured by NEC (NEC Corporation).
Use PD8255.

The display group 700 is each display device shown in FIG. 3, and includes, for example, an LED (light emitting diode) or an LCD.
(liquid crystal display) is used. Also key group 60
0 represents each key in FIG. 3, and the CPU 801 is configured to know which key has been pressed using a known key matrix.

[0052]H. Example of Operation Next, an example of the copy density control operation when the present invention is applied to the show-through prevention process of a copying apparatus will be described. The state quantities when performing copy density control include (1) a paper thickness state quantity of the copy document obtained from the paper thickness measurement sensor 900 for measuring the paper thickness of the copy document, and (2) a state quantity of the document density obtained from the AE sensor 815 or higher. We use two state quantities.

The control amount when performing copy density control is ■
The light intensity of the halogen lamp 103 is used.

FIG. 5 shows the membership functions of the state quantities and control quantities described above. (A) to (C) in FIG. 5 each represent the following contents.

Curve μA in FIG. 5(A): Membership function of document density Curve μB in FIG. 5(B): Membership function of document paper thickness Curve μC in FIG. 5(C): Halogen lamp 103 Next, a procedure for calculating the light amount of the halogen lamp 103 using fuzzy inference from the document density and paper thickness will be described.

[0056] Normally, fuzzy control
The amount of control is determined by fuzzy inference performed using a collection of language inference rules of the type ``. In the present invention, for example, as shown in FIG. 6, fuzzy inference is performed using the following inference rules. The contents of this inference rule can be freely changed using external storage means such as the IC card 901 in FIG.

(Inference Rule 1) If Original Density (AE) is PSand Paper Thickness (D) isN
B Then halogen lamp light intensity (U) isNS (inference rule 2) If document density (AE) isPBand paper thickness (D) isN
S Then halogen lamp light amount (U) isNB In this way, inference rules are set as necessary.

FIG. 7 shows an example of calculating the halogen lamp light amount control amount by fuzzy inference using the above (inference rule 1) and (inference rule 2).

As an example, consider the case where the original density value=x and the paper thickness value=y.

In the antecedent part of (inference rule 1), according to the membership function (μA) of the document density, it belongs to the set of PS with the fitness of μA-PS(x) for the input value x, and the paper thickness By the membership function, μB for the input value y
−NB(y) belongs to the set of NBs. Then, take the minimum value of μA-PS(x) and μB-NB(y), and that value satisfies the condition of inference rule 1, μC-
Let it be the fitness of NS. If we take the MIN (minimum value) calculation between that value and the membership function of the halogen lamp light intensity, we get
It becomes a trapezoid indicated by the diagonal line S. Similar calculations are performed for (inference rule 2), and the trapezoid shown by the oblique line of T can be derived. After that, a new set indicated by the diagonal line U is created using the maximum value of the S set and the T set. The center of gravity value W of this set U is used as the light amount control value of the halogen lamp 103. The same thing is done for the fuzzy rule shown in FIG.

Next, referring to the flowchart of FIG.
The entire operating procedure of the embodiment of the present invention will be explained.

First, the density of the original is calculated using the output of the AE sensor 815 (step S1), and then the paper thickness of the original is calculated using the output of the paper thickness sensor 900 (step S1).
2).

[0063] After that, for all the inference rules, the degree of fitness of the control amount to the fuzzy set is calculated from the degree of fitness of the state quantity to the fuzzy set according to each inference rule using the method described above (steps S3 and S4). The maximum value of the set to which it belongs is calculated (step S5). The most likely control amount is calculated by determining the center of gravity (step S6), and the center of gravity value is calculated by determining the center of gravity of the halogen lamp 103.
is set as the control amount of the light amount (step S7).

(2) Second Embodiment Another embodiment of the present invention that can achieve the same effects as the above embodiment will be described below.

FIG. 9 shows the basic configuration of a show-through prevention mechanism of an image forming apparatus according to a second embodiment of the present invention. In FIG. 9,
139-2 is a control circuit that controls the developing bias according to instructions from the CPU 801; 139-1 is a developing sleeve. The rest of the configuration is similar to the embodiment shown in FIG.

In the case of this embodiment as well, the hardware configuration and circuit configuration used are similar to those of the first embodiment described above. Therefore, A. in the first embodiment. ~G. The description of the items will be omitted.

Next, an example of the copy density control operation according to the second embodiment of the present invention will be described. As a state quantity when performing copy density control ■Paper thickness measurement sensor 9 for measuring copy document paper thickness
This embodiment is similar to the first embodiment in that two state quantities are used: the paper thickness state quantity of the copied original obtained from 00 and the original density state quantity obtained from the AE sensor 815. However, unlike the first embodiment, the control amount when performing copy density control is
The amount of developing bias voltage of the developing sleeve 139-1 is used.

FIG. 10 shows the membership functions of the state quantities and control quantities described above. (A) to (C) in FIG. 10 represent the following contents, respectively.

Curve μA in FIG. 10(A): Membership function of document density Curve μB in FIG. 10(B): Membership function of document paper thickness Curve μD in FIG. 10(C): Developing sleeve 139 -1
Membership function of developing bias voltage Next, a procedure for calculating the developing bias voltage using fuzzy inference from the original density and paper thickness will be described.

In this embodiment, fuzzy inference is performed using, for example, the following inference rules.

(Inference Rule 1) If Original Density (AE) is PSand Paper Thickness (D) isN
B Then development bias voltage (U) isNM (inference rule 2) If original density (AE) isZOand paper thickness (D) isN
S Then developing bias voltage (U) isNS In this way, inference rules are set as necessary. The inference rules in this case are shown in FIG.

The fuzzy inference procedure performed using the inference rules as shown in FIG. 11 is the same as that described in the first embodiment, and will therefore be omitted.

Next, the entire operating procedure of the second embodiment will be explained with reference to the flowchart of FIG.

First, the density of the original is calculated using the output of the AE sensor 815 (step S11), and then the paper thickness of the original is calculated using the output of the paper thickness sensor 900 (step S12).

After that, for all the inference rules, the degree of fitness for the fuzzy set of the control amount is calculated from the degree of fit for the fuzzy set of the state quantity according to each inference rule using the method described above (steps S13 and S14), and The maximum value of the set to which it belongs is calculated (step S15). The most likely control amount is calculated by determining the center of gravity (step S16), and the center of gravity value is set as the control amount of the developing bias voltage (step S17).

(3) Third Embodiment Another embodiment that can achieve the same effects as the first and second embodiments described above will be shown below.

FIG. 13 shows the basic configuration of a show-through prevention mechanism of an image forming apparatus according to a third embodiment of the present invention. Whereas in the first and second embodiments described above, the copying density can be controlled by controlling the density of the latent image using the halogen lamp light intensity or the developing bias voltage, in the third embodiment By controlling the voltage, the contrast of the entire image can be controlled, making it possible to control the copy density.

In FIG. 13, 135-1 is the CPU 80.
This is a control circuit that controls the primary charging voltage based on instructions from 1. 135 is a primary charger. Other configurations are shown in Figure 1.
This is similar to the embodiment.

In the case of this embodiment as well, the hardware configuration and circuit configuration used are similar to those of the first embodiment. Therefore, A. in the first embodiment. ~G. The description of the items will be omitted.

Next, an example of the copy density control operation according to the third embodiment of the present invention will be described. As a state quantity when performing copy density control ■Paper thickness measurement sensor 9 for measuring copy document paper thickness
This embodiment is similar to the first and second embodiments in that two state quantities are used: the paper thickness state quantity of the copied original obtained from 00 and the original density state quantity obtained from the AE sensor 815. However, unlike the first and second embodiments, (2) the amount of primary charging voltage of the primary charger 135 is used as the control amount when performing copy density control.

FIG. 14 shows the membership functions of the state quantities and control quantities of (1) to (2) above. (A) to (C) in Fig. 14
Each represents the following contents.

Curve μA in FIG. 14(A): Membership function of original density Curve μB in FIG. 14(B): Membership function of paper thickness Curve μE in FIG. 14(C): Member of primary charging voltage Ship Function Next, a procedure for calculating the primary charging voltage using fuzzy inference from the document density and paper thickness will be described.

In this embodiment, for example, fuzzy inference is performed using the following inference rules (inference rule 1
) If Original density (AE) is PSand Paper thickness (D) isN
B Then primary charging voltage (U) isNS (Inference rule 2) If original density (AE) isZOand paper thickness (D) isN
S Then primary charging voltage (U) isZO In this way, inference rules are set as necessary.

[0084] The inference rules in this case also follow the above-mentioned first and second rules.
Similar to the inference rules in the embodiment, it can be constructed empirically.

The fuzzy inference procedure is the same as that described in the first embodiment, and will therefore be omitted.

Next, the entire operating procedure of the third embodiment will be explained with reference to the flowchart of FIG.

First, the density of the original is calculated using the output of the AE sensor 815 (step S21), and then the paper thickness of the original is calculated using the output of the paper thickness sensor 900 (step S22).

After that, for all the inference rules, the degree of fitness of the control amount to the fuzzy set is calculated from the degree of fitness of the state quantity to the fuzzy set according to each inference rule using the method described above (steps S23, S24). The maximum value of the group to which it belongs is calculated (step S25). The most likely control amount is calculated by determining the center of gravity (step S26), and the center of gravity value is set as the control amount of the primary charging voltage (step S27).

(4) Other Embodiments The control variables according to the present invention are not limited to those exemplified in the above embodiments, but may also include, for example, a threshold value, an amplification factor, etc. when converting the output signal of an image sensor for reading a document into a binary value. can also be applied. Also,
The image forming device is not limited to the copying device shown in Fig. 2, but can also be applied to an image reading device using a CCD image sensor or an optical character reading device. The present invention can also be applied to, for example, a facsimile machine connected via a line. Furthermore, a magneto-optical disk or the like can be used as the recording section.

[0090]

[Effects of the Invention] As explained above, according to the present invention,
In image forming apparatuses such as copying machines, which are subject to large fluctuations due to the environment and are dominated by ambiguous relationships between state quantities and control quantities, it is now possible to appropriately handle such ambiguous relationships by using fuzzy control. Image formation can be performed according to the current state of paper thickness, etc. This improves the quality of the image formed, prevents image bleed due to double-sided originals, and significantly improves the reliability of image formation.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of a show-through prevention mechanism according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the entire internal configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a plan view showing the appearance of the operation panel of the device shown in FIG. 2;

FIG. 4 is a block diagram showing a circuit configuration of a control system of the device shown in FIG. 2;

FIG. 5 is a graph representing an example of a membership function according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an example of stored contents of inference rules according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram showing the processing content of document illumination light amount control using the fuzzy inference method according to the first embodiment of the present invention.

FIG. 8 is a flowchart showing a document illumination light amount control procedure for preventing show-through according to the first embodiment of the present invention.

FIG. 9 is a block diagram showing the basic configuration of a show-through prevention mechanism according to a second embodiment of the present invention.

FIG. 10 is a graph showing an example of a membership function according to a second embodiment of the present invention.

FIG. 11 is an explanatory diagram showing an example of stored contents of inference rules according to the second embodiment of the present invention.

FIG. 12 is a flowchart showing a developing sleeve voltage amount control procedure for preventing show-through according to a second embodiment of the present invention.

FIG. 13 is a block diagram showing the basic configuration of a third embodiment of the present invention.

FIG. 14 is a graph showing an example of a membership function according to the third embodiment of the present invention.

FIG. 15 is a flowchart showing a primary charging voltage amount control procedure for preventing show-through according to a third embodiment of the present invention.

[Explanation of symbols]

100 Apparatus main body 103 Halogen lamp 135 Primary charger 139-1 Developing sleeve 200 Pedestal 300 RDF (circulating document feeder) 400 Staple sorter 800 Control device 801 CPU (Central Processing Unit) 803 RO
M (read-only memory) 805 RAM (random access memory) 807, 809 I/O (input/output interface) 815 AE sensor (density detection sensor for automatic density adjustment) 900 Paper thickness sensor (transmittance sensor) 901 IC card

Claims (4)

[Claims] 1. A detecting means for detecting a paper thickness state quantity corresponding to the paper thickness of a document, a measuring means for measuring a density state quantity corresponding to the density of the document, the paper thickness state quantity, and the density state quantity. and membership function storage means predetermined membership functions for each density control amount as a fuzzy quantity, and a membership function storage means that stores a membership function of the density control amount to determine the relationship between the membership of the paper thickness state quantity and the density state quantity. an inference rule storage means that stores an inference rule relating to the ship as a qualitative rule; and the paper thickness state quantity obtained from the detection means and the density state quantity obtained from the measurement means. , an inference means for executing fuzzy inference using the membership function and the inference rule and setting a target density control amount; and a control means for adjusting the output image density with the density control amount set by the inference means. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, further comprising rule changing means for changing the inference rule stored in the inference rule storage means. 3. The image forming apparatus according to claim 2, wherein the rule changing means is an input operation means or an external storage means. 4. The image forming apparatus according to claim 1, wherein the detection means is a sensor that detects light transmittance of the original.