JPH0723225A - Image forming device - Google Patents

Abstract

PURPOSE:To provide a image forming device capable of obtaining an excellent recording image with high image quality having gradation fidelity to an original image and having proper density. CONSTITUTION:In the image forming device applying digital processing to a density signal read from an original and recording the signal, an image signal processing section 60 applies fuzzy deduction to a brightness signal of the original read by an image read section 10 based on density distribution data, revises at least one of an offset and an inclination or the like of a curve of a conversion table to convert the read image density signal into a write signal and a proper conversion table is prepared in a conversion table section 63, the image density signal is converted into a write signal and the signal is fed to a laser write section 20. Furthermore, the device is provided with sensing means such as a temperature sensor, a moisture sensor, a toner density sensor and a photoreceptor surface potential sensor sending state variables of the image forming process and executes fuzzy inference and controls number of revolutions of a development sleeve based on the result of the inference.

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 printer having a control means using fuzzy inference.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, an information value relating to a state quantity obtained from a sensor installed in each section of the image forming apparatus is input to a control section, and a predetermined arithmetic processing is performed based on a program stored in advance. The calculation processing result is output as a control signal to the control target of each unit of the image forming apparatus as needed.

[0003]

However, in an image forming apparatus such as a copying machine, the control amount must be determined in consideration of many conditions, and the variation due to the environment is large, and the relationship between the state amount and the control amount is large. Is often controlled by an ambiguous relationship, and there is a problem in that a satisfactory independent control cannot be performed by a separate control method and control program for each factor.

An object of the present invention is to solve the above problems and
It is an object of the present invention to provide an image forming apparatus that obtains an excellent recorded image with high image quality that has gradation characteristics faithful to an original image by performing appropriate control by performing fuzzy inference on an ambiguous relationship in the image forming apparatus.

[0005]

In order to achieve the object of the present invention, the image forming apparatus of the first invention of the present application is an image forming apparatus for digitally processing and recording a density signal read from a document. Fuzzy inference is performed based on the density distribution data obtained from the density signal of the read document, and at least one of the offset and the slope of the curve of the conversion table for converting the read density signal into the writing signal is changed. , Using an appropriate conversion table.

The image forming apparatus according to the second aspect of the present invention relates to a control means capable of changing the rotation speed of the developing sleeve and an image forming process in the image forming apparatus which digitally processes and records the density signal read from the original. Means for detecting at least one state quantity, fuzzy inference is performed based on the state quantity, and the rotation speed of the developing sleeve is controlled according to the result of the inference.

The state quantity is at least one of temperature, humidity, developer density, patch density, photoreceptor surface potential, exposure power, cumulative number of copies, and photoreceptor rotation speed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing an image signal processing unit of the first invention. In the figure, 10 is an image reading unit which will be described later, 60 is an image signal processing unit, 61 is a CPU for performing fuzzy inference and other control, and 69A is an A for converting the image luminance information of the analog signal from the image reading unit 10 into a digital signal. A / D converter, 62A is a brightness / density converter for converting a brightness signal into a density signal, and 62B is yellow rather than blue (B), green (G) and red (R) signals provided in the case of a color copying machine.
(Y), magenta (M), cyan (C) and black (K) signals are converted into BGR / YMCK conversion units, 63 is a conversion table unit for converting image density signals into write signals, and 64A is fuzzy rules and members. ROM-1 for storing the ship function, 65 is a RAM used as a work area when performing fuzzy inference, 66 is a memory for storing a signal processed as a write signal by the image signal processing unit 60, and 20 is a laser writing unit. is there.

FIG. 3 is a sectional view showing the schematic arrangement of an example of an image forming apparatus common to the first and second inventions of the present invention. This image forming apparatus includes an image reading unit 10 and a laser writing unit 2
0, the image forming unit 30, the paper feeding unit 40 and the like.

A document table 11 made of a transparent glass plate or the like is provided above the image forming apparatus, and a document D placed on the document table.
There is a document placing portion including a document cover 11A that covers the first cover unit 11A, a second mirror unit 13, a main lens 14, an image sensor, and the like.
An image reading unit 10 including 15 and the like is provided. The first mirror unit 12 is provided with an illumination lamp 12A and a first mirror 12B, is mounted parallel to the document table 11 and is linearly movable in the horizontal direction of the drawing, and optically scans the entire surface of the document D. The second mirror unit 13 integrally includes a second mirror 13A and a third mirror 13B, and linearly moves in the same direction in the left and right directions at a speed half that of the first mirror unit 12 so as to always maintain a predetermined optical path length. Of course, the movement of the second mirror unit 13 is parallel to the platen like the first mirror unit 12. Document table illuminated by the illumination lamp 12A
The image of the original document D on 11 is transferred to the first mirror 12 by the main lens 14.
B, the second mirror 13A, the third mirror 13B, and then, for example, CC
An image is formed on the light receiving surface of the image pickup device 15 made of D. Prior to the image formation, preliminary scanning is performed to read the image brightness of the document D, and a conversion table to be described later is created. After the preliminary scanning is completed, the first mirror unit 12 and the second mirror unit 13 return to their original positions, and the above-mentioned conversion is performed again. The scanning is repeated to perform the main scanning for image formation. After the main scan, the first mirror unit 12
Then, the second mirror unit 13 returns to the original position and stands by until the next image formation.

The image data obtained by the main scanning is processed by the image signal processing unit 60 shown in FIG.
It is temporarily stored in the memory 66 as a write signal.

The image forming unit 30 has a drive motor M, a polygon mirror 25 having eight reflecting surfaces, and an fθ lens 26 for rotating an image signal from the memory under the control of the control unit.
The image recording operation is started when it is input to the laser writing section 20 which is a laser scanning optical system including a laser unit and the like. That is, the diameter provided with a phthalocyanine-based photoreceptor
The photosensitive drum 31 which is an image forming body of 80 mm rotates clockwise as shown by an arrow, and the photosensitive drum 31 is charged by a charger 32 to which a bias voltage is applied from a high voltage power source controlled by a constant current. The charging potential is about -700V. This charging potential is detected by the photoconductor surface potential sensor 32A.

After that, writing is performed on the photosensitive drum 31 by the laser writing unit 20, and an electrostatic latent image corresponding to the image of the original D is formed on the photosensitive drum 31.

Thereafter, the electrostatic latent image on the photosensitive drum 31 is formed by a developing device 33 containing a two-component developer and having a diameter of 40 mm.
Reversal development is performed by the toner of the developer carried by the developing sleeve 33A to which a bias voltage of 600 V is applied, and a visible toner image is formed. 33C is a developing unit 33 by magnetic force, for example.
A toner concentration sensor for detecting the toner concentration of the developer inside.

On the other hand, the paper feed cassette loaded in the paper feed unit 40
Transfer paper P of a designated size is carried out from 41A or 41B one by one by carry-out roller 42A, and is fed to registration roller 45 toward the image transfer portion via guides 43, 46 and carry-out roller 44. The fed transfer sheet P is a registration roller 45 that operates in synchronization with the toner image on the photosensitive drum 31.
And is delivered onto the photosensitive drum 31. This transfer paper P
The toner image on the photoconductor drum 31 is transferred by the action of the transfer device 34, separated from the photoconductor drum 31 by the charge removal action of the separator 35, and then sent to the fixing device 37 via the conveyor belt 36. After being melted and fixed by the heat fixing roller 37A and the pressure bonding roller 37B, the sheet is discharged to the tray 49 outside the apparatus by the sheet discharging rollers 38 and 48.

Reference numeral 47 is a tray for manual feeding, and the transfer roller 44 feeds the manual transfer paper to the registration roller 45.

The photosensitive drum 31 continues to rotate,
The toner remaining on the surface without being transferred is removed and cleaned by a cleaning blade 39A made of urethane rubber which is brought into pressure contact with the cleaning device 39, and then charged again by the charger 32 to perform the next image forming process. to go into.

Next, the image signal processing unit 60 of the present invention shown in FIG.
Will be described. Image reading unit by the preliminary scanning
When the image brightness signal read in 10 is converted into a digital signal by the A / D converter 69A and then input to the image signal processing unit 60, it is converted into a density signal by the brightness / density conversion unit 62 and is passed through the selector 68. Is input to the CPU 61. CPU61
Then, for example, as shown in FIG.
Range 2 ... Range n is set, and the frequency of density is counted for each range. Fuzzy inference is performed based on this frequency to create a conversion table suitable for the image of the document D in the conversion table unit 63.

For example, when the manuscript D is a newspaper, the frequency distribution is as shown in FIG. 4. From this, the membership function shown in FIG. 6 is used to set the offset d which is the writing start point of the curve of the conversion table of FIG. Determine the slope of the curve. FIG. 6A shows an example of the membership function in the case of determining the offset d of the curve from the frequency of range 1 in FIG. 4, and the inference rule is if frequency of range 1 is large then d is large.

If frequency of range 1 is small then d is small.

It is

FIG. 6B shows the slope a of the range A of the curve of FIG.
4 shows an example of a membership function with a frequency in the range 2 in FIG. 4, and the inference rule is if the frequency in the range 2 is large then the slope is large.

If frequency of range 2 is small, then slope is small.

[0025] Similarly, fuzzy inference is performed by taking in the results by the membership functions of the frequencies of the range 1 and the range 3 on both sides of the range 2. FIG. 6C is a diagram showing an example of the membership function of the output (slope a). Thus curve ranging 5 When the slope a is determined A (x = range 0 to x ₁₎ is determined. That is, when x is the level of the image density signal and y is the level of the writing signal, y = a
(X-d).

Similarly, the slopes b and c of the range B and the range C are determined. In the range B (the range of x = x _{1 to} x ₂ ), y = a (x
₁₋ d) + b (x−x ₁ ), and the range C (x = x _{2 to} x ₃
Range), y = a (x ₁ −d) + b (x ₂ −x ₁ ) + c
(X−x ₂ ). In this way, an appropriate conversion table is created according to the type of image. After that, the image density signal obtained by the main scanning is sent to the conversion table unit 63 by the selector 68, converted into the write signal by the conversion table, and then temporarily stored in the memory 66. In this way, the writing signal having the gradation suitable for the image of the original D is sent to the laser writing unit 20, and the image having the density and the contrast faithful to the original D can be obtained. For example, in a newspaper manuscript or the like, the light color of the background is cut (the density is set to 0) to form a copy image that is easy to see, and a copy image faithful to the manuscript can be obtained. The optimum one may be selected from a plurality of conversion tables already prepared based on the result of fuzzy inference, and the image density signal may be converted into a writing signal using this conversion table.

(Embodiment 2) Next, an embodiment of the second invention will be described. Since the image forming apparatus of this embodiment is exactly the same as that shown in FIG. 3, its detailed description is omitted. 2 is a block diagram showing a control system of the second invention. The same parts as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof will be omitted. In FIG. 2, 72 is a temperature sensor provided in the image forming apparatus of FIG. 3 for detecting the temperature inside the machine, 73 is a humidity sensor for detecting the humidity inside the machine, and 69B is A / D conversion for converting an analog signal into a digital signal. 64B is a ROM-2, 67 for storing fuzzy rules and membership functions.
Is a development sleeve rotation speed control circuit (control means capable of changing the rotation speed of the development sleeve) for controlling the rotation speed of the development motor 33M for driving the development sleeve 33A.

Next, the control of the rotation speed of the developing sleeve 33A of this embodiment will be described with reference to the flow chart shown in FIG.

As described in the first embodiment, when the main scanning is performed following the preliminary scanning of the image reading unit 10 and the image formation is started, the temperature sensor 72 and the humidity sensor 73 for detecting the state quantity relating to the image forming process, The toner concentration sensor 33C and the photoconductor surface potential sensor 32A convert the detected result (analog signal) into a digital value via the A / D converter 69B and send it to the CPU 61. The CPU 61 determines whether or not 200 ms before the development of the developing device 33 is started (step 1). When 200 ms before, the output value of each sensor is sampled and held and fetched (step 2). The CPU 61 carries out fuzzy inference based on the fetched numerical value, determines the rotational speed of the developing sleeve 33A suitable for the state at that time (step 3), and sends a control signal to the developing sleeve rotational speed control circuit 67 to rotate the developing motor 33M. The number of rotations of the developing sleeve 33A is changed by controlling the number (step 4). Subsequently, the CPU 61 carries out image formation (step 5). When the image formation is completed, the CPU 61 returns to move to the next image formation.

As an example of the membership function used in step 3, the membership function of the toner concentration of the developer is shown in FIG. In FIG. 7, LL indicates very low, L is low, H is high, and HH is very high, and the toner concentration (%) of the developer is plotted on the horizontal axis.

The inference rule at this time is that if the toner density is low, then the toner density is then the developing sleeve.
Increase the rotation speed of 33A.

If toner density is high then developing sleeve
Lower the rotation speed of 33A.

Regarding the temperature inside the machine, if the temperature is higher then
The rotation speed of the developing sleeve 33A is increased.

If temperature is low then the rotation speed of the developing sleeve 33A is lowered.

Regarding the internal humidity, if the humidity is high then
Lower the rotation speed of the developing sleeve 33A.

If Humidity is low then the rotation speed of the developing sleeve 33A is increased.

Regarding the surface potential of the photoconductor, the if potential is high.
Then the rotation speed of the developing sleeve 33A is lowered.

If the potential is low then the rotation speed of the developing sleeve 33A is increased.

[0039]

Since the number of revolutions of the developing sleeve 33A is controlled by carrying out fuzzy inference using such an inference rule, the developer can be conveyed according to the state quantity of the apparatus and a constant copy density can be always obtained. Like

[0041]

Since the image forming apparatus of the present invention is configured as described above and fuzzy control is performed, the first invention can obtain a high quality copy image having gradation characteristics faithful to the original image. Further, according to the second aspect of the present invention, it is possible to provide an image forming apparatus capable of always obtaining an excellent copy image of high quality having an appropriate density even if the state quantity of the apparatus changes.

[Brief description of drawings]

FIG. 1 is a block diagram showing an image signal processing unit of a first invention.

FIG. 2 is a block diagram showing a control system of a second invention.

FIG. 3 is a cross-sectional view showing a schematic configuration of an example of an image forming apparatus of the present invention.

FIG. 4 is a diagram showing an example of a frequency distribution of document density.

FIG. 5 is a diagram showing an example of a curve of a conversion table.

FIG. 6 is a diagram showing an example of a membership function of the first invention.

FIG. 7 is a diagram showing an example of a membership function of the second invention.

FIG. 8 is a diagram showing a flowchart of a second invention.

[Explanation of symbols]

 10 Image reading unit 20 Laser writing unit 21 Laser unit 30 Image forming unit 31 Photoconductor drum 32A Photoconductor surface potential sensor 33 Developer 33A Development sleeve 33C Toner density sensor 33M Development motor 60 Image signal processor 61 CPU 62A Brightness / density conversion 62C BGR / YMCK converter 63 Conversion table section 64A ROM-1 64B ROM-2 65 RAM 66 Memory 67 Development sleeve rotation speed control circuit 68 Selector 69A A / D converter 69B A / D conversion section 72 Temperature sensor 73 Humidity sensor

Claims (2)

[Claims] 1. An image forming apparatus for digitally processing and recording a density signal read from a document, fuzzy inference is performed based on density distribution data obtained from the density signal of the read document, and the read density signal is obtained. An image forming apparatus, wherein at least one of a curve offset and a slope of a conversion table for converting into a writing signal is changed and an appropriate conversion table is used. 2. An image forming apparatus for digitally processing and recording a density signal read from a document, the control means capable of changing the rotation speed of a developing sleeve, and means for detecting at least one state quantity related to the image forming process. And perform fuzzy inference based on the state quantity,
An image forming apparatus, wherein the number of rotations of the developing sleeve is controlled according to the result of the inference. The state quantity is at least one of temperature, humidity, developer density, patch density, photoreceptor surface potential, exposure power, cumulative number of copies, and photoreceptor rotation speed.