JPH07288680A - Image forming device - Google Patents

Abstract

PURPOSE:To attain data conversion attended with setup of collation data with high precision and with publication of new bank notes by forming a storage memory for collation data to be a replaceable memory so as to replace the memory with other memory and providing a protector function. CONSTITUTION:R,G,B outputs of a line sensor 207 are inputted to an evaluation means 21 via A/D converters 7-9. The means 21 compares density signals by a collation data storage section 21b and a pattern comparison section 21a and provides an output of an evaluation signal representing it that an original inhibits a replica to an entire control section via an interface section 20. The storage section 21b is formed to be a replaceable control ROM form such as a ROM cartridge. Thus, collation data are converted and forgery of securities or the like is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus having a function of preventing image reproduction of securities and the like.

[0002]

2. Description of the Related Art In recent years, since high-performance color image forming apparatuses have become widespread, it is expected that crimes such as forgery of securities such as banknotes will frequently occur. To prevent such crimes, when reading and copying a color original digitally, the read signal is used to identify the collation data in the original, and the identified pattern is recognized as securities. In that case, a proposal has been made to cancel the copying operation (Japanese Patent Laid-Open No. 55-111977).

As a method for identifying a pattern, a method that employs a pattern matching method and a method that applies fuzzy theory to such a pattern matching method have been proposed (JP-A-4-302271 and JP-A-4-302267). Issue).
Securities matching means that employs such a pattern matching method uses incandescent lamps for the colors of matching data that specify a particular security from a plurality of types of securities using B (blue), G (green), and R (red). ) The color separation of the three primary colors is performed, the electrical signals are read by a line sensor, the electrical signals are A / D converted in multi-gradation to obtain the color signals of the three primary colors, and a discrimination dictionary that stores these color signals is provided. Therefore, a signal obtained by comparing the collation data with the read signal from the scanner, for example, is output from the discrimination dictionary. When the manuscript is judged to be securities, etc. from this output result, the whole or part of the image part is painted solid black and the transfer paper is ejected.
Forgery is prevented (Japanese Patent Laid-Open No. 2-210481).

[0004]

However, the discrimination dictionary described above is composed of a ROM memory which is not replaceable by the ASIC, and when a new banknote is issued or more accurate collation data can be established. Since the forgery discrimination unit is not compatible, it is possible to forge an unsupported unit.

Further, it is expected that some people may make it difficult to paint solid black and make the anti-counterfeit function defective by making the power source of the developing device loaded with black toner malfunction. Furthermore, by pulling out the discrimination dictionary, some people may disable the forgery prevention function.

A first object of the present invention is to provide an image forming apparatus capable of updating data associated with issuance of new banknotes and establishment of highly accurate verification data.

A second object of the present invention is to provide an image forming apparatus capable of discharging black or yellow, magenta or cyan solid even if a developing device loaded with black toner is inoperable. .

[0008]

As means for solving the first problem of the present invention, a reading means for reading an image from an original, an image forming means for forming the read image information on a recording medium, and the original. Is an image forming apparatus including an evaluation unit that evaluates that copying is prohibited according to a predetermined standard, and a control unit that changes subsequent processing to a degree according to the evaluation, and the evaluation unit is configured. The collation data is stored in a replaceable memory and a protect function is provided. This makes it possible to update the data associated with the issuance of new banknotes and the establishment of highly accurate verification data, and it is possible to prevent the forgery prevention function from being disabled or malfunctioning. Here, as a form of the control ROM that can be exchanged, there are a type that can be exchanged by an IC socket on a substrate of a storage device and a type of a ROM cartridge that stores the control ROM in a plastic package. The recording medium includes both a photosensitive drum and a transfer material and varies depending on the color image forming process adopted.

As means for solving the second problem of the present invention, a reading means for reading an image from a document, an image forming means for forming the read image information on a recording medium, and a copy forbidden by the document. An image forming apparatus including an evaluation unit that evaluates the presence of a black toner on an image forming body according to a predetermined standard. It is characterized in that at least one toner image forming process of yellow, magenta, and cyan is added according to the evaluation result. As a result, it is possible to form a solid image of black, yellow, magenta, or cyan even though the developing device loaded with black toner is inoperable, and thus it is possible to prevent counterfeiting of securities and the like.

[0010]

EXAMPLE An example of the image forming apparatus according to the first and second aspects of the present invention will be described.

FIG. 7 is a sectional view showing an embodiment of the image forming apparatus of the first and second inventions.

The multicolor image forming apparatus 1000 of this embodiment is shown in FIG.
Color scanner 200 that reads the original image as shown in
Then, every time the image carrier 339 rotates, it is charged by the charger 331,
A color separation electrostatic latent image is formed on the image bearing member 339 by image exposure by the writing device 310, and a plurality of color toners necessary for reproducing the electrostatic latent image in full color are individually loaded and magnetically charged. The developing devices 332 to 335 by the brush developing method are selectively operated to visualize the toner image, and the toner image is transferred to the image carrier 339.
The toner image of each color is superposed on the image carrier 339 by repeating the series of processes for forming a plurality of times for each color, and then the transfer device 3 is applied to the transfer material sent from the paper feed cassette 341.
The electrophotographic process unit 300 that is collectively transferred by the fixing roller 36 and then fixed by the fixing roller 345, and an evaluation unit 21 that evaluates that copying is prohibited from a so-called density signal according to a predetermined standard (see FIG. 1). Control) and the control 800 (FIG.
), A network control unit 940 (see FIG. 2), and the like. Each member will be described in detail below.

The color scanner 200 corresponds to a reading means, and the configuration of the optical system and the signal processing system will be described below.

The structure of the optical system of the color scanner 200 will be described with reference to FIG.

As shown in FIG. 7, the color scanner 200 is provided on a moving member that moves a document positioned at a reference position of the platen 201 by mounting a light source 202 that emits white light from below. Mirror 20 that reflects the light of
3 and a second mirror 204 that reflects the light from the first mirror 203
And a pair of the third mirror 205 and the V mirror portion, and the light from the V mirror portion is supplied to the line sensors 207B, 207G, 207.
An image forming lens 206 that forms an image on the light receiving portion of R, a prism, two dichroic mirrors, and a line sensor 207R that captures a red color separation image, a line sensor 207G that captures a green color separation image, and a blue color sensor 207G. By including the line sensor 207B that captures a color separation image, the optical signals obtained by the above-described optical system are collected by the imaging lens 206,
The dichroic mirror provided in the prism described above causes color separation into blue optical information and yellow optical information.
Further, the dichroic mirror separates the yellow optical information into red optical information and green optical information. In this way, the color optical image is made up of the three colors of red R, green G and blue B by the prism.
It is decomposed into color optical information. The respective color separation images are formed on the light receiving surfaces of the respective line sensors 207B, 207G and 207R, whereby color signals converted into electric signals are obtained. The image signal is processed by the signal processing system, and then the recording signal of each color is sent to the writing control unit 22.

As a result, the reflected light image from the image portion of the original is received by the line sensors 207B, 207G, 207R and the color signal is sent to the signal processing system line by line. Here, the color signal is obtained after MTF correction of the effects of the MTF of the lens in the optical system, the mounting accuracy of the line sensor and the vibration of the optical mirror or the like in the optical traveling system, and the fluctuation of the scan speed.

The MTF correction mentioned here is to correct the fluctuations of the MTF of the lens, the accuracy of the prism surface and the scanning speed in the optical system constituting the writing device 310, which directly affects the deterioration of the resolution, into the density signal. In order to improve the reproducibility in the finest part of the image, the MTF value needs to be 30% or more, and the strength of the MTF correction is determined by edge enhancement, smoothing, and anti-moire.

Next, the circuit configuration and function of the signal processing system will be described.

FIG. 1 is a block diagram showing the circuit arrangement of a signal processing system provided in the color scanner of this embodiment.

The pulse generating section (not shown) is a pulse generating circuit for generating a reference clock as an operation timing, and the switch S (not shown) is controlled by a control signal from the electrophotographic process control section 810 (see FIG. 2). Is closed to supply the reference clock to the color scanner 200 (not shown), the signal processing system and the writing device 310 (not shown). As a result, the reading operation of the color signals received by the line sensors 207B, 207G, 207R is executed. Here, the switch S is normally open. Therefore, when the control signal is applied from the electrophotographic process control unit 810, the closed state is set. This control signal is sent to the color scanner 200
It is also a signal for starting scanning of the reading optical system. It is obvious that the opening / closing operation of the switch S can be realized by software.

The signal processing system is the line sensor 207 described above.
Shading correction is performed on the color signals from B, 207G, and 207R, and at the same time analog / digital conversion is performed and output as a density signal of 256 gradations. The density signal is subjected to MTF correction, γ correction, and gradation correction in an arbitrary order, and the recording signal is sent to the writing control unit 22, and the A / D converters 7 to 9 and the shading are performed. Correction circuit
10 to 12, gates 13 to 15 for extracting only the effective width, B, G,
A density converting circuit 16 for converting an R color signal into a density signal, a color reproducing section 17 for outputting a color code, a selector 18 for selectively passing a recording signal, and a multi-valued data by multi-value processing of a digital color signal. A multi-value processing unit 19 for converting into a so-called density signal, an evaluation unit 21 for evaluating a so-called density signal which is prohibited from being copied according to a predetermined standard, and an interface for outputting a digital color signal, a color code and an evaluation signal to the outside. The unit 20 is provided. The interface unit 20 sends the color code and the evaluation signal to the control 800.

The color reproduction section 17 is provided with a color reproduction table composed of a ROM for each recording signal of Y, M and C, and one of them is selected to execute the reproduction processing. In the color reproduction table, data for color reproduction is written for each of Y, M, C and K. It should be noted that if character color and gradation image color reproduction tables are separately provided and selected by an image discrimination signal, both character images and gradation images can be clearly reproduced. In this case, the character reproduction table is written with data that emphasizes the clear reproduction of characters and the like, and forcibly reproduces a subtle light shade or a color close to an achromatic color in black and white. The tone reproduction table is written with data that emphasizes faithful reproduction of the original image and expresses subtle light shades or colors close to achromatic color as they are.

As shown in FIG. 2, the evaluation means 21 evaluates that the duplication is prohibited from the density signal of 256 gradations, based on various evaluation results, showing the degree of ambiguity with the securities. The signal is sent out and the pattern comparison unit
21a and a collation data storage unit 21b. The pattern comparison unit 21a sends an evaluation signal to the control 800 via the interface unit 20.

The pattern comparison unit 21a is a collation data storage unit 21.
It is carried out by performing a comparison operation with the data registered in advance in b, an evaluation is carried out by comparing a comprehensive image pattern of a part or the whole of the document, and further, those processes are used together. Features are extracted from the contents of the read image data.

The collation data storage unit 21b is in the form of a replaceable control ROM, which can be replaced by an IC socket on the substrate of the storage device, or a ROM cartridge containing a control ROM in a plastic package. By doing so, it is possible to update data associated with the issuance of new banknotes and the establishment of highly accurate verification data, and the relevant ROM's color spectrum distribution and a comprehensive image pattern of part or all of the document (this The collation data) and the size of the original are written. The collation data referred to here is the color of the collation data that identifies a particular security from multiple types of securities, and is separated into three primary colors of B (blue), G (green), and R (red) using an incandescent lamp. The line sensor reads it as an electric signal, and the electric signal is A /
The D-converted color signals of the three primary colors are obtained, and these color signals are coded.

In this embodiment, when the undercolor process is executed and the black component does not exist in the recording color or the other recording colors do not exist, the color code indicating the corresponding recording color is not transmitted from the interface section 20. .

Next, the structure of the electrophotographic process unit 300 used in the multicolor image forming apparatus of this embodiment will be described with reference to FIG.

The electrophotographic process unit 300 includes a charging device 331,
It is composed of developing devices 332 to 335, a transfer device 336, a separating device 337, a cleaning device 338 and an image carrier 339, and forms an image on a recording paper by executing an electrophotographic process of charging, developing, transferring and separating. It is a thing.

Here, an electrophotographic process for forming a multicolor image in the electrophotographic process unit 300 will be described.

In the electrophotographic process section 300, when the recording signal sent from the color scanner 200 is input to the write control section 22, the write control section 22 shows a laser beam generated by a semiconductor laser (not shown). Not pass through the collimator lens and the cylindrical lens, and is rotationally scanned by the rotating polygon mirror that is rotated by the motor, and the optical path is bent by the two mirrors between the fθ lens and the cylindrical lens, and is evenly distributed by the scorotron charger 331 in advance. The electrostatic latent image (hereinafter, also simply referred to as a latent image) is formed by being projected onto the peripheral surface of the image carrier 339 to which various electric charges have been applied to perform main scanning.

On the other hand, when scanning is started, the laser beam is detected by an index sensor (not shown), and the first
The laser beam modulated by the color signals of the image carrier 339
On the peripheral surface of. Therefore, a latent image corresponding to the first color is formed on the peripheral surface of the image carrier 339 by the main scan by the laser beam and the sub-scan by the conveyance of the image carrier 339. This latent image is subjected to reversal development by the developing device 332 loaded with the yellow toner that is selectively operated, and the image carrier 3
39 A toner image is formed on the surface. The obtained toner image passes under the blade of the cleaning device 338 separated from the peripheral surface of the image carrier 339 while being held on the surface of the image carrier 339, and enters the next image forming cycle.

That is, the image carrier 339 is recharged by the charger 331, and then the second color signal is input to the writing control section 22. In the same manner as in the case of the first color signal described above, the image carrier is carried.
339 Writing is performed on the surface to form a latent image. The latent image is subjected to reversal development by the developing device 333 loaded with magenta toner as the second color which is selectively activated.
This magenta toner image is formed in the presence of the previously formed yellow toner image.

Similarly, a developing device 334 having cyan toner forms a cyan toner image on the surface of the image carrier 339 in the same manner as the first and second colors.

Finally, a developing device 335 having black toner
Then, a black toner image is formed on the image carrier 339 in the same manner as in the above-described color. These developing devices 33
DC and further AC biases are applied to the sleeves 2, 333, 334, and 335, and the image carrier 339 undergoes reversal development without contact. The above is the process of superimposing multicolor toner images on the image carrier 1.

Thus, the multicolor toner image formed on the peripheral surface of the image carrier 339 is transferred to the transfer material sent from the paper feed cassette 341 through the paper feed guide to a high voltage having a polarity opposite to that of the toner at the transfer portion. Is applied and transferred.

That is, the transfer material accommodated in the paper feed cassette 341 is conveyed to the uppermost one by the rotation of the paper feed roller 342, and is aligned with the leading edge of the image on the image carrier 339 via the timing roller 343. And is supplied to the transfer device 336.

The transfer material which has received the transfer of the image is surely separated from the rotating image carrier 339 and is directed upward, and after fixing the image by the fixing roller 345, the image is fixed by the discharging roller 346 and then the tray (not shown). Discharged on top.

On the other hand, the image carrier 33 that has finished the transfer to the transfer material
9 is a cleaning device 338 in which the blade and the toner conveying roller are kept in pressure contact with each other to remove the residual toner, and after the end, the blade is separated again, and a little later, the toner conveying roller is separated and a new toner is removed. Enter the image formation process.

The main constituent features of the electrophotographic process section 300 will be described below.

The writing device 310 is for emitting a semiconductor laser based on a recording signal sent from the writing control section 22 to line-scan the image carrier 339 dot by dot to form a latent image. A so-called exposure process is performed, in which a semiconductor laser is oscillated by a modulation signal, laser light is deflected by a polygon mirror 314 rotating at a predetermined speed, an fθ lens 315, a first cylindrical lens (not shown), and a second lens. Image carrier 339 by a cylindrical lens (not shown)
The scanning is performed by narrowing down to a minute spot.

The scanning optical system constituting the writing device 310 is provided with a semiconductor laser as a coherent light source, a collimator lens 313 as a modulation optical system, a polygon mirror 314 and an fθ lens 315 as a deflection optical system, and a polygon mirror. A first cylindrical lens and a second cylindrical lens are provided as a surface tilt correction optical system by 314.

The write controller 22 is a modulation circuit (not shown).
An LD drive circuit (not shown), an index sensor (not shown) and a index detection circuit (not shown) as a synchronization system, and a polygon driver (not shown) as a deflection optical system are provided.

The modulation circuit compares the reference wave with the analog recording signal obtained by D / A converting the recording signal consisting of a predetermined bit and multi-values it. The modulation signal thus obtained becomes the drive signal for the LD drive circuit. LD drive circuit,
A semiconductor laser is oscillated by a modulation signal, and a signal corresponding to the light amount of the beam from the semiconductor laser is fed back and driven so that the light amount becomes constant, and the current conducted to the semiconductor laser is changed. You can do it. Thereby, the latent image potential can be adjusted. The synchronization system enters an index sensor (not shown) via a mirror (not shown) that reflects the beam from the deflection optical system. The index sensor outputs a current in response to the beam, and the current is converted into a current / voltage by an index detection circuit and output as an index signal. The surface position of the polygon mirror 314 that rotates at a predetermined speed is detected by this index signal, and optical scanning is performed by a modulation signal in a raster scanning system at a cycle in the main scanning direction.

GaAlAs or the like is used as the semiconductor laser, the maximum output is 10 mW, the optical efficiency is 25%, and the divergence angle is 8 to 16 ° parallel to the joint surface and 20 to 36 ° perpendicular to the joint surface. Since color toners may be sequentially superposed on each other, exposure with light having a wavelength that is less absorbed by the color toners is preferable, and the wavelength in this case is 780 nm.

The collimator lens 313 is a lens that efficiently extracts a beam with a required diameter, has a numerical aperture NA of 0.33, and is made up of a lens having a transmittance of 97% or more to improve the spherical aberration and the symmetry. It is a thing. The lens is a lens having a small refractive index.

The prism (not shown) is a prism having a transmittance of 80 or more and compresses the beam diameter from the semiconductor laser to 1/3. The deflection angle is finely adjusted by a screw or the like (not shown).

The deflection optical system collects the beam and reduces the Pepper sum and the astigmatic difference in order to realize the flattening of the scanning surface.

The polygon mirror 314 is provided with eight polygon surfaces, for example 1653 at a writing density of 400 dpi.
It rotates at 5.4 (rpm) and a writing density of 600 dpi at a rotation speed of 11023 (rpm), and scans the beam on the image carrier 339.

The fθ lens 315 reduces the Pepper sum and the astigmatic difference in order to realize the flattening of the scanning surface, and removes the field curvature.

A polygon mirror 314 is used as the correction optical system.
Before and after the first cylindrical lens (not shown) and the second
A cylindrical lens (not shown) is provided to reduce the unevenness of the scanning line pitch due to the surface tilt error of the polygon mirror 314. As a result, the polygon tilt angle is 120 seconds PP, and the tilt angle correction rate is 1'20 or more. The second cylindrical lens forms an image of the beam on the image carrier 339.

The image carrier 339 is formed by forming a photosensitive layer on the surface of a conductive base material made of, for example, aluminum. The photosensitive layer has a film thickness of 15 to 30 μm and a dielectric constant of 2.0 to 5.0.
The conductive base material is grounded and the linear velocity is 280 (mm / sec) or 12
It is a drum-shaped photoreceptor having a diameter of 180 mm, which is composed of a (-) charged coating type OPC that rotates in the arrow direction at 5 (mm / sec).
An encoder EK (see FIG. 2) for detecting the phase is provided on the rotation axis of the image carrier 339, and the encoder EK outputs a phase signal indicating the phase of the image carrier 339 to the electrophotographic process control unit 810 (see FIG. 2). ) Is sent to.

A charging device 331, developing devices 332 to 335, a separating device 337, and a transfer device 33, which will be described later, are provided on the peripheral portion of the image carrier 339.
6, a cleaning device 338 is provided, and a paper feed tray 341,
A paper feed system including a registration roller 343, a conveyor belt 344 and the like is provided.

The charging device 331 is, for example, a scorotron charger, and prevents fog by adjusting the gradation reproducibility etc. by uniformly charging the image carrier 339 to a predetermined voltage prior to the latent image forming process. .

The developing devices 332 to 335 each include a toner made of a polyester material having an average particle diameter of about 8.5 μm and a ferrite coating carrier having an average particle diameter of 60 μm and a toner concentration of 4 to.
After stirring the developer controlled to 6% by rotating the stirring screw at 120 (rpm), the magnetic brush is placed on the outer circumference of the sleeve which is outside the magnet roller and rotates at about 400 (rpm) or 180 (rpm). Then, a predetermined bias voltage is applied to the developing sleeve to visualize the latent image in the developing area facing the image carrier 339 as a toner image.

The reason why the two-component non-contact developing method is adopted in the multicolor image forming method of this embodiment is that the toner particles can control triboelectric charging relatively easily and the toner particles are less likely to aggregate. Therefore, the magnetic brush has good ears, is excellent in friction with the surface of the image carrier, and has a feature that a sufficient cleaning effect is exhibited even when it is used for cleaning. More importantly, the surface of the image carrier is important. This is because it is also suitable for non-contact development that develops in non-contact with.

The constitution using the magnetic brush developing method can be applied to the one-component non-magnetic developer and the one-component magnetic developer. Although the developing devices 332 to 335 have been described as developing the latent image in this embodiment, the present invention is not limited to this, and it is obvious that a magnetic latent image can also be visualized.

As is well known, the transfer device 336 is an image carrier 339.
The transfer paper is superposed on the electrostatically carried toner image, and the toner is transferred onto the transfer paper by discharging the electric charge from the back side of the transfer paper, which is preferably a scorotron discharger. However, the toner image is not limited to the above, and may be any one that electrostatically transfers a toner image onto a transfer paper such as a corotron charger or a charging roller.

As is well known, the separating device 337 separates the transfer paper by electrostatically removing it from the transfer paper electrostatically adsorbed on the image carrier 339, and includes a scorotron charger, a corotron charger, a charging roller, etc. To use.

The cleaning device 338 brings the image carrier 339 into contact with the surface of the image carrier 339 with a blade or the like.
The toner and dust adhering to the surface of the is scraped off and captured in the waste toner box.

As is well known, the fixing device 345 is a device for permanently fixing the toner image on the transfer paper by applying heat or heat and pressure to the transfer paper carrying the toner image, and the lower roller is 70 μm. PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) coated rubber with a thickness of 30 °, for example L
It is made of TV (abbreviation of Roten Paracher Vulcanizing) and contains a 200W electric heater. The upper roller has a diameter of 50mm and a total length of 324mm, eg A5056TD.
(Aluminum) made of core material and P on the surface
It is FA-coated, and a fixing temperature sensor is provided on the surface of a heating roller containing a 1100 W electric heater (not shown). The fixing temperature sensor is composed of, for example, a thermistor or the like, and detects the surface temperature of the upper roller including the electric heater as an output voltage of about 5 V at maximum, and the temperature sensor controls the fixing temperature to, for example, 180 ° C. It is used.

A paper discharge sensor (not shown) is provided in the path on the discharge side from the fixing device 345, and sends a detection signal for detecting the rear end of the transfer paper to the electrophotographic process control unit 810.

The electrophotographic process unit 300 of this embodiment is used.
Adopts a color process of forming a color image by superimposing a toner image on the image carrier 339 as described above, but is not limited to this, and a method of superimposing a toner image on a transfer body. May be Further, in the present embodiment, an electrophotographic process unit 300 that forms an image by an electrophotographic method will be described as an image forming unit, but the present invention is not limited to this, and image formation by another method such as an inkjet method. It may be a means.

Next, the control circuit of the electrophotographic process section 300 will be described with reference to FIG.

FIG. 2 is a block diagram showing a main configuration of a control circuit in one embodiment of the image forming apparatus of the first and second aspects of the present invention.

The control 800 is provided by an electrophotographic process control unit 810 composed of a microprocessor in which a program for executing an electrophotographic process is written, and a communication control and operation display unit (not shown) with an external device. An overall control unit 820 including a microprocessor that supports data input and interrupt processing.

The electrophotographic process control unit 810 sequentially drives the electrophotographic process members described above based on the phase signal from the encoder EK, and receives the color code and the evaluation signal from the interface unit 20. The number of toner colors to be visualized in advance and the platen 20
It is possible to detect the degree of ambiguity between the original placed on the document 1 and securities, and whether or not the image formation body 339 is visualized with black toner according to the evaluation signal. By this, a program is written to add at least one toner image forming process of yellow, magenta, and cyan.

The density detection sensor 910 is provided with a light emitting source capable of projecting light over the entire width of the image forming body 339 and an optical system capable of receiving reflected light from at least the entire image area of the image forming body 339, for example, a line sensor or the like. The light receiving element of the
The output signal is sampled from the light receiving element at a time corresponding to one screen when the color development process is completed.

The background color of the image carrier 339 usually has a chromatic gloss such as blue or green, whereas the black toner does not reflect light, so that the level is lower than the reflection density from the image carrier 339. It is to detect whether or not the black toner image is carried on the image carrier 339 based on the presence or absence of the time of substantially zero level.

The sampling time is set to start from the tip of the image area based on the phase signal from the encoder EK. The present invention is not limited to this, and sampling may be continued if the time corresponding to the image area can be specified from the phase signal from the encoder EK.

Although the reflected light from the entire image area of the image forming body 339 is received in the present embodiment, the invention is not limited to this, and the reflected light from one part of the image area is displayed on one screen. The sampling may be performed at a time corresponding to, and further, it is not necessary to perform sampling over the entire time corresponding to one screen, and a part may be sufficient.

The voltage detecting means 920 detects the output voltage from the developing bias circuit 950. By monitoring this output by the electrophotographic process control section 810, each developing device 3
The malfunction of 32 to 335 can be detected.

The switching means 930 may be a high breakdown voltage switching element, but in the present embodiment, the same function as this is realized by software as a control signal for controlling the output voltage of the developing bias circuit 950.

Developing sleeves 332Y, 333M, 334C, 335K
Are provided for the developing devices 332 to 335, respectively, and are illustrated in a simplified manner.

The overall control unit 820 also has a function of performing communication control for performing communication with an external device through the communication line 941, and is connected to a management place outside the image forming apparatus 1000 and other installed external devices. It also enables communication such as data exchange between the devices periodically or at any time. By providing the image forming apparatus with a means for storing the ID and password of the other party who permits the communication start request, It is possible to prevent unauthorized access when the password is leaked (the specific configuration is described in JP-A-4-318746). The overall control unit 820 is connected via an RS-232C interface (not shown) (not shown). When data is transferred from the overall control unit 820 via this RS-232C interface, the transfer data is transferred. RAM provided in a network control unit (hereinafter abbreviated as NCU unit) 940
(Not shown), and after the data transfer from the control 800 is completed, the overall control unit 820 controls the NCU 940 to establish a communication line connection with the outside, and a line connection modem, N
Data can be transferred to the outside through the CU unit 940.

In the present embodiment, the control 800 is realized by two micro-processors, but it is not limited to this, and it may be realized by software on two or more or a single microprocessor. Good.

The operation display unit (not shown) is an LCD (liquid crystal) type message touch display for displaying information relating to copying, and displays characters and figures with, for example, 96 × 192 dots. Matched in addition to the number of copies made, the standard scaling key, the same size key, the copy magnification set with the zoom key, the paper size selected with the copy paper selection key, a message indicating the status of the image forming device body, a guide message indicating the operating procedure It displays the degree and warning message. Thereby, the guidance index for the user is displayed.

The operation of the image forming apparatus of this embodiment from the power-on to the end of the image forming operation will be described below.

FIG. 3 is a memory map of the ROM storing the collation data.

Reference numeral 4 is a storage area of the ROM for storing the collation data, and the storage contents which are not allowed to be rewritten are controlled by the control program or initialization after power-on according to the flowchart of FIG. 4, or control after recovery of the reset state of the microprocessor. Store the procedure etc. Reference numeral 5 is a storage area of the ROM 3. A control program storage area 6 is a specific recognition code (hereinafter referred to as an ID code) written at the head address of the control program storage area. Also, the built-in ROM of the microprocessor is a ROM for storing collation data.
In order to determine whether or not it is necessary to write the ID code of the ROM for storing collation data. In other words, instead of replacing all the control ROMs, the control R
The common part that does not need to be replaced by the contents of the OM is stored in the non-replaceable ROM, and the ID code for identification is stored in the non-replaceable ROM and the replaceable ROM. With such a configuration, it is possible to update data associated with issuance of new banknotes or establishment of highly accurate verification data.

In the present embodiment, since the evaluation means 21 is provided in the signal processing system of the scanner, the microprocessor for writing and executing the program in which the protect function for realizing the protect function is written in the control ROM. (Not shown) are individually provided. However, the present invention is not limited to this, and by sending B, G, and R color signals to the control 800 via the interface unit 20,
It is also possible to provide the evaluation means 21 in the control 800.

FIG. 4 is a flow chart of control for realizing the protect function of this embodiment, FIG. 5 is a flow chart showing a forgery prevention operation, and FIG. 6 is a flow chart showing a color image forming process.

Main switch MS (see FIGS. 1 and 2)
After turning on the power by connecting the
After releasing the reset state of the microprocessor constituting 0, control after initialization or reset state release is performed (step S1), and then various data is received from the color scanner 200 via the interface unit 20 to perform the electrophotographic process. Prior to starting, the microprocessor 23 reads the ID code of the collation data storage ROM 21b (step S2) and determines whether or not the inserted collation data storage ROM 21b is the storage ROM (step S3). If the ROM is different, an error state (step S5) is set so that the image data is not sent from the color reproducing unit 17 via the interface unit 20. When it is determined that a replaceable control ROM is inserted incorrectly,
An alarm device consisting of an LED and a buzzer notifies the error state. On the other hand, if it is a ROM for storing collation data, the electrophotographic process control unit 810 sends a standby signal permitting execution of the electrophotographic process program to the controller 800 (step S100).

In the electrophotographic process control section 810, when the recording signal sent from the multi-value quantization processing section 19 is input to the write control section 22, the write control section 22 generates a semiconductor laser (not shown). The laser beam passes through a collimator lens and a cylindrical lens (not shown), is rotationally scanned by a rotary polygon mirror that is rotated by a motor M, passes through an fθ lens and a cylindrical lens, and the optical path is bent by two mirrors between them, and the scorotron charging is performed in advance. An electrostatic latent image (hereinafter also simply referred to as a latent image) for reproducing yellow by being projected onto the peripheral surface of the image carrier 339 to which uniform charge is applied by the device 331 and performing main scanning is formed. To do.

On the other hand, when scanning is started, the laser beam is detected by an index sensor (not shown), and the laser beam modulated by the yellow signal is transferred to the image carrier 339.
On the peripheral surface of. Therefore, a latent image corresponding to yellow is formed on the peripheral surface of the image carrier 339 by the main scan by the laser beam and the sub-scan by the conveyance of the image carrier 339 (step S101). This latent image is subjected to reversal development by the developing device 332 loaded with yellow toner which is selectively operated, and a toner image is formed on the surface of the image carrier 339 (step S102). The obtained toner image passes under the blade of the cleaning device 338 separated from the peripheral surface of the image carrier 339 while being held on the surface of the image carrier 339,
Enter the next image forming cycle.

That is, the image carrier 339 is recharged by the charger 331, then the magenta signal is input to the writing control section 22, and the image carrier is processed in the same manner as in the case of the yellow signal described above.
339 Writing is performed on the surface to form a latent image (step S103). The latent image is subjected to reversal development by the developing device 333 in which magenta toner is loaded as the second color which is selectively activated (step S104). This magenta toner image is formed in the presence of the previously formed yellow toner image.

Similarly, a cyan signal is input to the writing controller 22, and writing is performed on the surface of the image carrier 339 in the same manner as described above to form a latent image (step S105). Next, in the developing device 334 having cyan toner, the first and second
A cyan toner image is formed on the surface of the image bearing member 339 in the same manner as the color of step S106 (step S106).

Finally, a black signal is input to the writing control section 22, writing is performed on the surface of the image carrier 339 in the same manner as described above to form a latent image (step S107), and development with black toner is carried out. The device 335 forms a black toner image on the image carrier 339 in the same manner as the above-described color (step S108). Developing devices 332, 333, 334 and 33
DC and further AC biases are applied to the sleeves 5 and non-contact reversal development is performed on the image carrier 339.
The above is the process of superimposing multicolor toner images on the image carrier 1.

Next, a forgery prevention processing routine is executed (step S120).

Since the electrophotographic process control section 810 has received the evaluation signal via the interface section 20, if the evaluation signal does not determine that it is securities (step S12).
1) The process exits from the routine and the electrophotographic process (steps S109 to S112) described later is executed.

If the electrophotographic process control unit 810 determines that the securities are securities based on the evaluation signal in the anti-counterfeiting processing routine (step S121), the phase signal from the encoder EK is extracted from the leading end to the trailing end of the image area of the image forming body 339. The reflected light is sampled through the density detection sensor 910. The electrophotographic process control unit 810 determines that the image forming body 3
The presence / absence of a level lower than the reflection density from the background of 39 to a substantially zero level (hereinafter, black determination level) is detected (step S122). Here, if the electrophotographic process unit 810 determines that black toner is present, an exposure and development process is added to superimpose the black toner image on the entire image area of the image forming body 339 (step S124). The process (steps S109 to S112) will be executed. This makes it possible to prevent illegal copying of securities and the like by painting in black.

On the other hand, if the electrophotographic process section 810 determines that there is no black toner in step S122, whether the black developing operation is executed from the color code from the interface section 20 and whether or not the black developing operation has been performed, and the voltage detecting means. 920
By detecting the output from, the malfunction of the developing device 335 loaded with black toner is detected. Accordingly, when the malfunction of the developing device is detected, one of the developing devices 332 to 334 is selected from the presence or absence of the color code to select the image forming body 33.
An exposure and development process is added to superimpose the toner images on all the nine image areas (step S123). Thus, regardless of the malfunction of the developing device 335 loaded with black toner, it is possible to prevent illegal copying of securities and the like by reproducing as a black portion and a discolored image that do not exist in the original.

Thus, the multicolor toner image formed on the peripheral surface of the image carrier 339 is transferred to the transfer material sent from the paper feed cassette 341 through the paper feed guide to a high voltage having a polarity opposite to that of the toner at the transfer portion. Is applied and transferred (step S10)
9).

That is, the transfer material accommodated in the paper feed cassette 341 is conveyed to the uppermost one by the rotation of the paper feed roller 342, and is aligned with the leading edge of the image on the image carrier 339 via the timing roller 343. And is supplied to the transfer device 336 (step S110).

The transfer material which has received the transfer of the image is surely separated from the rotating image carrier 339 and is directed upward, and after the image is fixed by the fixing roller 345 (step S111), the transfer material passes through the paper discharge roller 346 and the tray ( It is discharged onto the upper surface (not shown) (step S112).

On the other hand, the image carrier 33 which has finished the transfer to the transfer material.
9 is a cleaning device 338 in which the blade and the toner conveying roller are kept in pressure contact with each other to remove the residual toner, and after the end, the blade is separated again, and a little later, the toner conveying roller is separated and a new toner is removed. Enter the image formation process.

In the above-mentioned electrophotographic process, it has been described that all color codes exist, but the present invention is not limited to this, and there are cases in which there is no color code indicating at least one or more recording colors. In that case, the exposure / development process for the corresponding recording color is omitted from steps S101 to S108 shown in FIG. Further, it is within the scope of the present invention to execute the exposure and development process using the density signal of the density level of zero for the convenience of software preparation.

[0097]

According to the first aspect of the present invention, with the above configuration, it is possible to provide an image forming apparatus capable of updating data associated with issuance of new banknotes and establishment of highly accurate verification data. Furthermore, it has been possible to prevent the inability of the forgery prevention function from being disabled due to incorrect installation of the collation data storage means.

According to the second aspect of the present invention, with the above construction, even if the developing device loaded with black toner is inoperable, it can be discharged as solid black or yellow, magenta or cyan, thereby preventing forgery. It was possible to provide an image forming apparatus capable of doing so.

[Brief description of drawings]

FIG. 1 is a block diagram showing a signal processing system of a color scanner which constitutes an image forming apparatus according to first and second aspects of the invention.

FIG. 2 is a block diagram showing a main configuration of a control circuit in one embodiment of the image forming apparatus of the first and second aspects of the invention.

FIG. 3 is a memory map of a ROM storing collation data.

FIG. 4 is a flowchart of control for realizing the protect function of the present embodiment.

FIG. 5 is a flowchart showing a forgery prevention operation.

FIG. 6 is a flowchart showing a color image forming process.

FIG. 7 is a cross-sectional view showing an embodiment of the image forming apparatus of the first and second aspects of the present invention.

[Explanation of symbols]

 21 Evaluation means 21b Collation data storage unit 200 Color scanner 300 Electrophotographic process unit 800 Control 910 Density detection sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location H04N 1/46 G03G 21/00 552 H04N 1/46 Z (72) Inventor Yoshihisa Kamada Tokyo Hachioji City Ishikawacho 2970 Konica stock company (72) Inventor Masato Kanno 2970 Ishikawacho, Hachioji, Tokyo Konica stock company (72) Inventor Kenji Izumimiya 2970 Ishikawacho, Hachioji, Tokyo Konica stock company (72) Inventor Kenichi Matsuo 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Eiji Anzai 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock company (72) Inventor Motohiro Takashima 1-chome Nishihashimoto, Sagamihara-shi, Kanagawa No. 16-18 Stock Company Alps Giken

Claims (2)

[Claims] 1. A reading unit for reading an image from a document, an image forming unit for forming the read image information on a recording medium, and an evaluation that copying of the document is prohibited according to a predetermined standard. In the image forming apparatus, the image forming apparatus is provided with an evaluation unit that performs the above-described evaluation and a control unit that changes the subsequent processing according to the degree of the evaluation. Image forming apparatus. 2. A reading means for reading an image from a document, an image forming means for forming the read image information on a recording medium, and an evaluation that copying of the document is prohibited according to a predetermined standard. In the image forming apparatus provided with the evaluation means, a means for detecting whether or not the image formation body is visualized with black toner is provided, and at least yellow, magenta, and
An image forming apparatus, wherein any one of the toner image forming processes of cyan is added.