JPH07147633A - Image forming device - Google Patents

Abstract

PURPOSE:To improve the security of a specified pattern by verifying the speci fied pattern by comparing it with the same specified pattern before a change even when the specified pattern is illegally changed. CONSTITUTION:Image data outputted from an image data processing part 209 and the specified pattern previously stored in a specified pattern memory A106 are added by an adder 105, the specified patterns in the specified pattern memory A106 and a specified pattern memory B109 are compared by a comparator 110 and when those specified patterns are matched, data outputted from the adder 105 are modulated, driven by a laser driver 202 and outputted as laser beams. On the other hand, when the specified patterns are not matched, the security invasion of the specified pattern memory A106 is judged, and the data outputted from the adder 105 are not outputted to the laser driver 202.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus and, for example, to an image forming apparatus capable of specifying a device that has formed the image from a formed image.

[0002]

2. Description of the Related Art Conventionally, with the improvement in image quality and color of image forming apparatuses such as printers and copiers, banknotes, securities, and other specific originals that should not be copied have been copied.
There was a risk of social problems of being used. In order to prevent the occurrence of this problem, as shown in Japanese Patent Laid-Open No. 4-294682, by adding a specific pattern such as a device number that is difficult to identify using the human visual characteristics to the output image of the image forming apparatus, A technique has been known in which the image forming apparatus that has output is specified.

FIG. 9 shows the structure of this conventional specific pattern adding section. In FIG. 9, the R, G, and B input signals are
It is input to the image data processing unit 1209, where it is converted into the corresponding Y, M, C, and K density image signals and output. The adder 1105 adds the image data output from the image data processing unit 1209 and the specific pattern stored in advance in the specific pattern memory 1210. The data output from the adder 1105 is the laser driver 12
It is modulated and driven at 02, then emitted by the semiconductor laser 1204, and output as a corresponding laser beam.

[0004]

However, in the above-mentioned conventional example, when the specific pattern is intentionally changed, it is not possible to specify the output device based on the specific pattern, which is a security problem for the specific pattern. It In order to solve such a problem, the present invention aims to improve the security of a specific pattern.

[0005]

A comparison for comparing a receiving means for receiving an image signal, a plurality of specific pattern storing means for storing a specific pattern, and a plurality of specific patterns stored by the plurality of specific pattern storing means. Means for replacing the image signal with predetermined invalid data when at least one of the plurality of specific patterns does not match as a result of the comparison by the comparing means, Of the specific patterns, and an output means for outputting an image signal in which one of the specific patterns is multiplexed by the multiplexing means, and the specific patterns are the same. It is characterized by being a pattern.

Further, the plurality of specific patterns are information patterns for identifying the device, and the plurality of specific patterns are repeatedly added to the output image at a predetermined cycle and store predetermined invalid data to be replaced by the replacing means. It is characterized by having invalid data storage means.

[0007]

With the above configuration, even if one specific pattern storage means is illegally changed, the specific pattern can be verified by comparing it with the specific pattern stored in the other specific pattern storage means, and the security of the specific pattern can be secured. Can be improved. That is, there is an effect that the counterfeit tracking function for bills and securities held by the image forming apparatus can be more guaranteed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described in detail below with reference to the drawings. <First Embodiment> A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a diagram showing a schematic configuration of signal processing of the laser beam printer of this embodiment. The laser beam printer of this embodiment shown in FIG. 1 is a terminal device that is connected to a computer via a predetermined interface cable and outputs the result of information processed by the computer onto a recording sheet.

In FIG. 1, 201 is a signal processing unit and 202
Is a laser driver, 203 is an amplifier, 204 is a semiconductor laser, 205 is a polygon mirror, 206 is an f-θ lens, 207 is a reflection mirror, and 208 is a photosensitive drum.
First, the image information is R (red), G (green), B
The signal is input as a (blue) component to the signal processing unit 201, and in the signal processing unit 201, the input signal is subjected to predetermined signal processing, and Y (yellow), M (magenta), C
(Cyan) and K (black).

Y, M, C converted by the signal processing unit 201
The image information of K and K is sent to the laser driver 202.
The laser driver 202 modulates the input Y, M, C, and K image information and outputs a modulated signal to the amplifier 203. The amplifier 203 drives the semiconductor laser 204 according to the modulation signal from the laser driver 202. Laser light output from the semiconductor laser 204 scans the photosensitive drum 208 via a polygon mirror 205, an f-θ lens 206, and a mirror 207.

Next, an outline of an actual printing process in the laser beam printer of this embodiment will be described with reference to FIG. In this embodiment, three-color (Y, M, C) or four-color (Y, M, C, K) toners are transferred one by one three times or four times by using a photoconductor and a transfer drum. The developing method will be described.

First, in the charging step 301, since the surface layer of the photosensitive drum 208 is formed by laminating a photoconductor on a conductive substrate, the surface potential of the photosensitive drum 208 is changed to an environment by a primary charger (not shown). The constant current control and the grid control are performed so that the surface of the photosensitive drum 208 is uniformly charged regardless of the conditions and the history of the photosensitive drum.

Next, in the exposure step 302, as described above with reference to FIG. 1, the photosensitive drum 208 is irradiated with laser light according to image information.
By scanning the top, an electrostatic latent image is formed on the photosensitive drum 208 by the electrostatic force according to the laser light. Next, in the developing step 303, the development of each color is performed to visualize the electrostatic latent image formed in the exposing step 302.
Details of the developing process 303 will be described below with reference to the detailed configuration diagram of the developing roller in FIG.

The developing roller 400 shown in FIG. 3 comprises a fixed magnet 403 and a magnetic cylinder (sleeve) 404 that rotates around the fixed magnet 403.
2 is charged by friction with the sleeve 404. Photosensitive drum 2
A distance of several hundreds of microns is maintained between the sleeve 08 and the sleeve 404, and the toner 402 is caused to fly in the alternating magnetic field while the toner 402 is adhered onto the photosensitive drum 208 in accordance with the electrostatic latent image formed in the exposure step 302. As a result, the electrostatic latent image is visualized.

As described above, in the developing step 303 shown in FIG. 2, the electrostatic latent image is visualized with toner. Next, in a transfer step 304 shown in FIG. 2, the print sheet supplied in the supply step 309 is brought into contact with the photosensitive drum 208 in synchronism with each other, and a charge having a polarity opposite to that of the toner is applied to the surface of the print sheet by the transfer charger. As a result, the toner on the photosensitive drum 208 is transferred onto the print paper.

In the subsequent drum cleaning process 306, the residual toner on the photosensitive drum 208 is removed by a cleaning blade (not shown) from the photosensitive drum 208 on which the visible image is printed. It should be noted that the exposure process 302, the development process 303, the transfer process 304, and the drum cleaning process 306, which have been performed so far, are performed three times according to the number of colors used, for example, three times for Y, M, and C, and Y, M, and C. , K, when the transfer is completed for all the colors that are repeated four times, then in a separation step 305, the print sheet on which the toner image has been transferred in the above-described transfer step 304 is separated from the photosensitive drum 208.

Next, in the fixing step 307, the toner transferred onto the print paper is heated and fixed by a fixing roller (not shown), and the toner image is fixed on the print paper. Then, in the paper discharge step 308, the print paper on which the toner image is fixed is discharged. As explained above,
The color printing in this embodiment ends.

Next, the addition of a specific pattern in the signal processing unit 201 shown in FIG. 1 will be described below. Figure 4
FIG. 9 shows a block diagram of a schematic configuration of the specific pattern adding unit in the signal processing unit 201 in this embodiment. In FIG. 4, reference numeral 209 denotes an image data processing unit that performs image processing such as converting input R, G, B image data into corresponding Y, M, C, K image signals, and 106, 107 denote The specific pattern memories A, B and 110 are comparators for comparing the specific pattern data of the specific pattern memories A and B, 202
Is a laser driver that drives a semiconductor laser according to an image signal. Further, 105 is an adder, and 111 is a switch.

The specific pattern adding process in the signal processing unit 201 shown in FIG. 4 will be described below with reference to the flowchart of FIG. First, in step S601, the image data is input from the image data processing unit 209, and then the image data output from the image data processing unit 209 in step S602 and the specific pattern previously stored in the specific pattern memory A106 are added. It is added by the instrument 105.

Then, in step S603, the comparator 110 compares the specific pattern stored in the specific pattern memory A106 with the specific pattern stored in the specific pattern memory B109. Then, as a result of the comparison, if the specific pattern stored in the specific pattern memory A106 and the specific pattern stored in the specific pattern memory B109 match, the process proceeds to step S604, the selector 111 is connected to the A side, The data output from the adder 105 is modulated by the laser driver 202 and output from the semiconductor laser 204 as a laser beam.

On the other hand, in step S603, if the specific pattern stored in the specific pattern memory A106 does not match the specific pattern stored in the specific pattern memory B109, the security of the specific pattern memory A106 is compromised. As a matter of course, the process is step S.
In step 605, the selector 111 is connected to the B side, and the data output from the adder 105 is the laser driver 202.
Is not output to. Then, the process proceeds to step S604, and the data other than the image data input by the image data processing unit 209 is modulated and driven by the laser driver 202 and output as a laser beam.

Further, a detailed configuration of the signal processing unit 201 when the above-mentioned specific pattern monitoring function is provided is shown in a block diagram of FIG. First, R, G, and B image data are converted into LOG conversion units 101, 102, and 103 of the image data processing unit 209.
Entered in. Each of the LOG converters 101, 102, and 103 is configured by a look-up table (LUT) ROM (read-only memory), and the input R, G, B luminance signals are converted into Y, M, C density signals. It Also, U
The CR (Under Colore Remove) unit 104 uses the known undercolor removal method to input the three primary color signals (Y, M,
C) is masked, and Y, M, and
The C and K signals are sequentially output, and the signal output from the UCR unit 104 is input to the adder 105.

The specific pattern memory A106 is RO
It is composed of M and stores a specific pattern to be added in advance. The specific pattern stored in the specific pattern memory A 106 is also input to the adder 105. In the adder 105, the original color of the image data is not changed by adding the specific pattern to the image data. , The density is averaged by area gradation.

The addresses of the specific pattern generation memory A 106 are the main scanning counter 107 and the sub scanning counter 108.
Controlled by. The HSync signal input to the main-scanning counter 107 and the sub-scanning counter 108 is a synchronization signal in the main-scanning direction, and defines the main-scanning start position in the "H" section. Further, the VSync signal input to the sub-scanning counter 108 is a synchronizing signal in the sub-scanning direction, and defines an image valid period in which the image is valid in the "H" section.

The main scanning counter 107 is reset by the HSync signal and generates an address as an n-bit counter by the clock (CLK) signal. Further, the sub-scanning counter 108 is reset by VSync, and HS
An image line is formed by counting up with the ync signal. FIG. 7 shows a timing chart showing the memory address control by the main scanning counter 107 and the sub-scanning counter 108 described above. In FIG. 7, an ellipse represents an example of the existence of each pixel of a specific pattern.

Main scan counter 107 as described above
The specific pattern stored in the specific pattern generation memory A 106 is repeatedly formed at regular intervals by the address counter including the sub-scanning counter 108. Specific pattern memory A106 formed as described above
The specific pattern stored in is added to the image data at the time of printing Y (yellow) by utilizing the fact that the human eye has a low identification ability with respect to the pattern drawn with the toner of Y (yellow). To do.

On the other hand, the second specific pattern memory B109
Is also a ROM and stores a specific pattern similar to that of the specific pattern memory A106. The comparator 110 compares the specific pattern stored in the specific pattern memory A106 with the specific pattern stored in the specific pattern memory B109. In order to make successive comparisons. The comparator 110 described above
An example of the comparison process in step 1 will be described with reference to FIG.

For example, the specific pattern shown in FIG. 8A is expanded from the specific pattern memory A 106, and the specific pattern shown in FIG. 8B is also expanded from the specific pattern memory B 109 in the same manner. Is input to the comparator 110. The comparator 110 is composed of a digital comparator and has a specific pattern memory A10.
When the specific pattern output from 6 and the specific pattern output from the specific pattern memory B109 match
L "is output, and the A side is selected by the selector 111.

On the other hand, FIG. 8C shows an example of the specific pattern when the content of the specific pattern memory A 106 is changed. In this case, in the comparison by the comparator 110, the specific pattern output from the specific pattern memory A106,
The specific patterns output from the specific pattern memory B109 do not match, "H" is output and the selector 111 selects the B side, and the memory C112 forces the image data to be, for example, all black data.

As described above, according to the present embodiment, by matching the specific pattern, it is possible to prevent the image data from being output when the specific pattern is changed and to improve the security of the specific pattern. it can. <Other Embodiments> The present invention is not limited to the above-described first embodiment, and is also effective in the cases described below.

In the above-mentioned first embodiment, the security of the specific pattern is ensured by the pattern matching between the specific patterns registered in advance in the ROM, but the present invention is not limited to this example, and for example, the first specific RO pattern
It is also possible to register in M and control the generation of the second specific pattern by a CPU (arithmetic processing unit). It is also conceivable to input the first specific pattern using a barcode.

Further, as the specific pattern to be added, it is possible to use not only the serial number peculiar to the device or a coded version thereof, but also any information for specifying the device. Further, in the above-described first embodiment, two specific pattern memories in which specific patterns are stored are prepared, but the present invention is not limited to this, and for example, a predetermined number of three or more specific patterns may be stored. good.

Further, in the above-described first embodiment, when the abnormality of the specific pattern is detected, the process sequence of exposure, development and transfer is increased by one step and the black toner is used for filling. Not limited to this, other toners may be used. That is, the present invention is characterized in that a sequence for changing a predetermined process step when the specific pattern is changed is added to the process step when the normal specific pattern is added. Therefore, in the above-described first embodiment, the number of process steps is increased by one, but conversely, by reducing the number of process steps, the same effect as in the first example can be obtained.

Although the laser beam printer has been described as the first embodiment according to the present invention, the present invention is not limited to this, and an ink jet printer, a dot matrix printer, a facsimile, etc. Image forming apparatus. It should be noted that the present invention can be applied to a system composed of a plurality of devices as well.
It may be applied to an apparatus composed of one device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0035]

As described above, according to the present invention, even if a specific pattern is illegally changed, the specific pattern can be verified by comparing it with the same specific pattern as before the change. Can improve the security of. That is, there is an effect that the counterfeit tracking function for bills and securities held by the image forming apparatus can be more guaranteed.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of signal processing in a first embodiment according to the present invention.

FIG. 2 is a block diagram showing an outline of a printing process in this embodiment.

FIG. 3 is a diagram showing a detailed configuration of a developing roller in this embodiment.

FIG. 4 is a block diagram showing a schematic configuration of a specific pattern adding unit in the present embodiment.

FIG. 5 is a flowchart showing a process of a specific pattern adding unit in this embodiment.

FIG. 6 is a block diagram showing a detailed configuration of a specific pattern adding unit in the present embodiment.

FIG. 7 is a timing chart showing memory address control in this embodiment.

FIG. 8 is a diagram showing a developed image of a specific pattern memory in the present embodiment.

FIG. 9 is a block diagram showing a basic configuration of a conventional specific pattern adding unit.

[Explanation of symbols]

 201 image signal processing unit 202 laser driver 203 amplifier 204 semiconductor laser 205 polygon mirror 206 f-θ lens 207 reflection mirror 208 photosensitive drums 101 to 103 LOG conversion unit 104 UCR unit 105 adder 106, 109, 112 ROM 107 main scan counter 108 Sub-scanning counter 110 Comparator 111 Selector

Claims (4)

[Claims] 1. Input means for inputting an image signal, at least two specific pattern storage means for storing specific patterns, comparison means for comparing each specific pattern stored by each specific pattern storage means, and said comparison As a result of the comparison by the means, when the specific patterns are not the same, the replacement means for replacing the image signal with predetermined invalid data and outputting the replacement signal, and one of the plurality of specific patterns for a part of the image signal. An image forming apparatus comprising: a multiplex unit that multiplexes and outputs. 2. The image forming apparatus according to claim 1, wherein each of the specific patterns is an information pattern for specifying an apparatus. 3. The image forming apparatus according to claim 1, wherein the multiplexing unit repeatedly outputs the specific pattern on an output image at a predetermined cycle. 4. The image forming apparatus according to claim 1, further comprising invalid data storage means for storing predetermined invalid data to be replaced by the replacement means.