JP3595573B2 - Color image recording apparatus and color image recording method - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a color image recording apparatus and a color image recording method for printing and recording a color image including a specific pattern.
[0002]
[Prior art]
In recent years, color image recording apparatuses such as printers and copiers have made great progress in both performance improvement and spread, and full-color image recording apparatuses are also available in silver halide, thermal, electrophotographic, electrostatic Devices using a large number of output methods such as a recording method and an ink jet method have been developed, and high-quality images have been obtained and have begun to spread widely.
[0003]
However, new problems have arisen with this. The problem is that anyone can easily forge banknotes and securities using a full-color image recording apparatus. Accordingly, it is necessary to install a function for preventing forgery in the recording apparatus, and recently, various full-function preventing functions are installed in the full-color image recording apparatus.
[0004]
The most common method of this forgery prevention function is to print a regular dot pattern representing the model code of the recording device on the paper at the time of printing, and when a forged bill is found, This is a so-called tracking pattern method in which a model number is determined from a dot pattern hit on a recording device, and the recording device from which the device number has been output is specified. Since this dot pattern is printed on all the output images, it is general that the dot pattern is printed with the lowest visibility, that is, yellow which is inconspicuous.
[0005]
[Problems to be solved by the invention]
However, in the color image recording apparatus to which the above-described tracking pattern method is applied, when the image printed once after the tracking pattern is driven is read by a scanner or the like and printed again, the tracking pattern is driven twice. . For this reason, when the target image is a security, it is difficult to decode the pattern, and when the target image is another image, there is a problem that the image quality deteriorates particularly in a natural image.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a color image recording apparatus which prevents deterioration of image quality due to a specific pattern in printing and recording of the color image including the specific pattern. That is.
[0007]
[Means for Solving the Problems] and [Function]
In order to achieve the above object, the present invention is directed to a color image recording apparatus which performs a predetermined printing process on a full-color image signal input from the outside, and stores a model code unique to the image recording apparatus in advance. If, means for determining whether or not contain foreign code to the image signal, when said outer code is determined to include a removal means for removing the outer code from the image signal, and the external code before SL by combining specific model code to the image recording apparatus, means for generating a tracking code, and means for adding the tracking code to the image signal in which the outer code is removed, the image signal the tracking code is added and output means for printing out, the tracking code is output split from該追mark code and a specific model code to the an external code the image recording apparatus They are combined to so that.
[0008]
In the above configuration, the configuration is made so as to avoid the difficulty of decoding a specific pattern and the deterioration of image quality due to the pattern.
Further, another invention further comprises means for judging whether or not the image signal matches a specific image, and the removing means, wherein the image signal is not the specific image, and removing the external code if it contains external code.
[0009]
This configuration functions to prevent image quality deterioration of images other than the specific image.
[0010]
【Example】
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a sectional configuration diagram of a color image recording apparatus according to an embodiment of the present invention. In the color image recording apparatus according to the present embodiment, image recording is performed using color electrophotographic technology. The input density level is M (magenta), C (cyan), Y (yellow), and BK (black), each of which is transmitted as an image signal in 8 bits for each color in a frame-sequential manner. Further, in this embodiment, it is assumed that the above-mentioned tracking pattern is hit only on the Y plane.
[0011]
In the color image recording apparatus (hereinafter, referred to as an apparatus) shown in FIG. 1, first, the surface of the photosensitive drum 100 is uniformly charged to a predetermined polarity by the charging device 101, and the photosensitive member is exposed by the laser beam L. On the drum 100, for example, a first magenta latent image is formed. Next, in this case, a required developing bias voltage is applied only to the magenta developing device Dm, the magenta latent image is developed, and a first magenta toner image is formed on the photosensitive drum 100.
[0012]
On the other hand, the transfer paper P is supplied at a predetermined timing, and immediately before the leading end of the transfer paper P reaches the transfer start position, a transfer bias voltage (+1.8 KV) of the opposite polarity (for example, positive polarity) to the toner is applied to the transfer drum 102. Then, the first toner image on the photosensitive drum 100 is transferred to the transfer paper P, and the transfer paper P is electrostatically attracted to the surface of the transfer drum 102. Thereafter, the magenta toner remaining on the surface of the photosensitive drum 100 is removed by the cleaner 103, and the preparation for the next color latent image formation and development process is performed.
[0013]
Next, a second latent image of cyan is formed on the photosensitive drum 100 by the laser beam L, and the second latent image on the photosensitive drum 100 is developed by the developing unit Dc for cyan to form the second latent image of cyan. A second toner image is formed. Then, the cyan second toner image is transferred to the transfer paper P in accordance with the position of the magenta first toner image previously transferred to the transfer paper P. In the transfer of the second color toner image, a bias voltage of +2.1 KV is applied to the transfer drum 102 immediately before the transfer paper reaches the transfer portion.
[0014]
Similarly, the third and fourth latent images of yellow and black are sequentially formed on the photosensitive drum 100, and each of the latent images is sequentially developed by the developing devices Dy and Db, and is transferred to the transfer paper P first. The third and fourth toner images of yellow and black are sequentially transferred in alignment with the toner image, so that toner images of four colors are formed on the transfer paper P in an overlapping state.
[0015]
Next, in the apparatus according to the present embodiment, processing from receiving an RGB image signal from a host or a scanner to transmitting it to a printing unit (not shown) will be described. FIG. 2 is a block diagram for explaining a process of receiving an RGB image signal and transmitting it to a printing unit in the present embodiment. In the following description, yellow, magenta, cyan, and black are represented as Y, M, C, and BK.
[0016]
In FIG. 2, an 8-bit signal 207 of each of RGB transmitted from the host or the scanner 201 is first input to the image processing unit 202.
Therefore, before describing the image processing unit 202 illustrated in FIG. 2, a “tracking pattern” recognized and printed by the apparatus according to the present embodiment will be described.
FIG. 3 is a diagram illustrating the principle of printing a tracking pattern according to the present embodiment. Note that this apparatus prints at a resolution of 600 dpi (dots / inch).
[0017]
In FIG. 3, the density of the 6 × 6 pixels (reference numeral 301) in the hatched portion is added to the original image data at 256 gradations by α, and the 3 × 6 pixels (302) on both sides of the original image data are Conversely, the concentration is subtracted by α. This keeps the overall average density. As a result of this processing, the density is set to 255 when the density is 255 or more, and is set to 0 when the density is 0 or less.
[0018]
An area of 12 × 6 pixels formed by the above-mentioned reference numerals 301 and 302 is defined as one dot. The dots are formed at regular intervals in the main scanning direction, and the six lines on which the dots are formed are referred to as a 0th line, a 1st line, and so on.
Next, from the 0th line on which dots are formed, a line is formed at intervals of 24 lines in the sub-scanning direction, dots are formed on the next first and second lines, and after the 15th line is formed, the first line is formed again. Repeat the same from the line.
[0019]
Here, the horizontal phase difference (main scanning direction) between the position of the dot on the n-th line and the position of the dot on the (n + 1) -th line represents one digit of the machine number.
FIG. 4 is a diagram illustrating the phase of the tracking pattern according to the present embodiment. As shown in the figure, here, the phase difference can be from 0 to F in hexadecimal, so that 16 values from 0 to F can be taken per digit. Therefore, these dots can represent a 16-digit hexadecimal number, that is, a machine number having a 64-bit length. Then, when dots are hit up to the 16th line, the 0th line is hit again, and the same operation as above is repeated.
[0020]
FIG. 5 is a print example of a tracking pattern according to the present embodiment. Since this tracking pattern is printed on all the images to be printed, it is printed only on the yellow plane with low visibility as described above.
FIG. 6 is a diagram for describing recognition and removal of a tracking pattern according to the present embodiment. In the figure, reference numerals 601, 602, and 603 denote line buffers for six lines of R, G, and B, respectively. The R, G, and B signals input thereto are first stored in the buffer for six lines. .
[0021]
Here, as described above, since each dot of the tracking pattern is composed of 12 × 6 pixels, a reference area for 12 × 6 pixels as indicated by reference numerals 604, 605, and 606 is provided. Further, since the tracking pattern is hit only on the yellow plane, the pattern is included only in the signal B which is a complementary color of yellow.
[0022]
Therefore, the reference pattern of B is matched with the dot pattern prepared in advance for the reference area 606 of B, and further, the matching is not obtained for the reference areas 604 and 605 of R and G. The thing is judged as a dot.
When it is determined that the data is a dot, α is subtracted from the data in the 6 × 6 hatched portion of the data in the reference region, and α is added to the surrounding region. By this processing, the dots are completely erased.
[0023]
The above processing is performed while shifting the reference area one pixel at a time in the sub-scanning direction. When the buffer reaches the end, the lowest-order buffers of R, G, and B are output for one line, and the data in the buffer is output one line at a time. By shifting the signal downward, the R, G, and B signals for one line are newly stored in the uppermost buffer, and the above operation is repeated.
This process is performed until the end of the image, and the model code is decoded from the coordinates of the dots for which matching has been confirmed. Then, when the decoding is successful, a decoded 64-bit model code signal (hereinafter referred to as an external code signal) 208 shown in FIG. If the decoding has failed, all the 64 bits of the external code signal are set to 0 and sent to the encoding unit 204.
[0024]
Next, the color conversion processing unit 203 shown in FIG. 2 will be described.
The color conversion processing unit 203 receives the R, G, B signals 207 and the color designation signal 211. As described above, in this apparatus, since one screen of each color of Y, M, C, and BK is printed, the image data is image-sequential, that is, data of one screen of M, data of one screen of C, and data of one screen of Y. Data for one screen and then data for one screen of BK are sent in this order.
[0025]
Therefore, the color conversion processing unit 203 first converts the image data for one screen of RGB one pixel at a time into an 8-bit VDO (video) signal of an M signal. Next, conversion is performed in the order of the C signal, the Y signal, and the BK signal. In this conversion, known masking and UCR processing are added.
In the color conversion processing unit 203, which color data of M, C, Y, and BK is to be used to convert the input RGB signal is specified by a color designation signal 211 sent from the formatter unit. That is, the color designation signal 211 first designates M, and changes in the order of C, Y, and BK each time data for one screen is transmitted.
[0026]
A ROM 206 of FIG. 2 stores a 64-bit code (hereinafter, referred to as an internal code) representing the model number of the apparatus according to the present embodiment. Further, the encoding unit 204 creates a new code by combining the external code signal 208 input as a tracking pattern from the image processing unit 202 and the internal code signal 209 input from the ROM 206, and sends the new code to the multi-value processing unit 205. , As a code signal 210.
[0027]
Here, the new code is combined so that the original internal code and external code can be determined from the code. If all bits of the external code are 0, that is, if the original image does not include a tracking pattern, the combined code is made to match the internal code.
FIG. 7 is a detailed block diagram of the multi-level processing unit 205. In the figure, reference numeral 701 denotes a density correction unit that receives an 8-bit image signal of each of M, C, Y, and BK, and performs correction according to the output characteristics of a printing unit (not shown). The signal converted by the density correction unit 701 is input to the tracking pattern addition unit 702.
[0028]
The code signal 712 sent from the encoding unit 204 in FIG. 2 is input to the tracking pattern generation circuit 709. The tracking pattern generation circuit 709 generates a predetermined tracking pattern according to the input code signal, and inputs it to the tracking pattern adding unit 702. The tracking pattern adding section 702 adds the tracking pattern to the input video signal only when the input color specifying signal 710 specifies Y, and does not perform the addition for M, C, and BK.
[0029]
The video signal of each color processed in this manner is input to a PWM (pulse width modulation) unit 703, and the PWM unit 703 synchronizes an 8-bit image signal with a rising edge of an image clock PCLK 713 by a latch circuit 704. After being converted into a predetermined analog voltage signal by the D / A converter 705, it is input to the analog comparator 706.
[0030]
On the other hand, in the PWM unit 703, a triangular wave generation unit 708 generates a triangular wave according to the image clock PCLK, and inputs the triangular wave to the analog comparator 706. Then, the analog comparator 706 compares the two signals of the analog voltage and the triangular wave, and the analog comparator 706 outputs a PWM signal according to the result of the comparison. This PWM signal is inverted by the inverter 707, and a PWM signal to the printing unit is obtained.
[0031]
The apparatus according to the present embodiment has a printing capability of 600 dpi (dots / inch) and has means for switching the frequency (number of lines) of the triangular wave between 600 lines and 200 lines. Here, 600 lines and 200 lines mean that triangular waves having wavelengths of 1/600 inch and 1/200 inch are used at the time of comparison.
In the multi-level processing unit shown in FIG. 7, a triangular wave generating unit 708 generates a triangular wave of 600 lines and 200 lines, and which of these is input to the analog comparator 706 is input from a controller unit (not shown). The selection is made by switching the line number switch 715 in accordance with the line number switch signal 714.
[0032]
In the apparatus according to the present embodiment, when an image on which a tracking pattern is recorded is read and output by a scanner or the like, the tracking pattern is erased once and the same tracking pattern is again recorded. This processing is required because if the scanning pattern is read once and the tracking pattern is output as it is, the tracking pattern becomes unclear.
[0033]
As described above, according to the present embodiment, when a predetermined tracking pattern is included in an image input from the scanner or the host, the pattern is erased once, and the pattern is newly replaced with the new pattern during printing. By adding a tracking pattern in combination with a pattern representing a model code of the color image recording apparatus, decoding of the tracking pattern becomes easy, and deterioration of image quality can be prevented.
[0034]
The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.
Therefore, a modification of the above embodiment will be described below.
<Modification 1>
FIG. 8 is a block diagram showing a signal system until an RGB image signal is received from a host or a scanner and transmitted to a printing unit according to the present modification.
[0035]
An 8-bit RGB video signal 806 sent from the scanner or the host 801 shown in FIG. 8 is input to the securities determination unit 802. The securities determination unit 802 determines from the video signal 806 whether the input image is a security such as a bill. Here, for example, the security is determined by comparing with a specific pattern stored in advance.
[0036]
If the securities determination unit 802 determines that the input image is an image of securities, it turns on the determination signal 808. However, if it is determined that the security is not a security, the determination signal 808 is turned off.
In the next stage of the image processing unit 803, when the input determination signal 808 is ON, since the input image is a security, the RGB values of the video signal are reduced by 50, respectively. That is, a process of overlaying a predetermined amount of black on the image is performed.
[0037]
When the determination signal 808 is OFF, the input image is not a security, so that the same processing as the processing in the image processing unit according to the above embodiment is performed. That is, if a tracking pattern is included in the input image, the pattern is deleted. By this processing, the pattern can be removed from the image in which the tracking pattern is recorded by another model even though the pattern is not a security.
[0038]
Then, the color conversion processing unit 804 generates M, C, Y, and BK signals sequentially designated by the video signal input from the image processing unit and the color designation signal 807, and inputs the signals to the multi-level processing unit 805. .
FIG. 9 is a block configuration diagram of the multi-level processing unit 805 according to the present modification. The density correction unit 901 shown in FIG. 9 performs density correction by a predetermined density correction method, and the converted signal is input to a PWM (pulse width modulation) unit 902. In the PWM unit 902, the 8-bit image signal is synchronized with the rising edge of the image clock PCLK 909 by the latch circuit 903, converted into an analog voltage by the D / A converter 904, and then input to the analog comparator 905.
[0039]
On the other hand, the triangular wave generator 907 generates a triangular wave by the image clock PCLK, and inputs the generated triangular wave to the analog comparator 905. Then, the analog voltage and the triangular wave are compared with each other, and the analog comparator 905 outputs a PWM signal with a predetermined pulse width. The signal is inverted by the inverter 906, and the desired PWM signal is output. can get.
[0040]
With such a configuration, paying particular attention to securities, if the image input from the scanner or the host is not a security and the image contains a predetermined tracking pattern, the tracking pattern is deleted. Can be printed.
<Modification 2>
Next, a second modified example according to the above embodiment will be described.
[0041]
FIG. 10 is a block diagram for explaining a process of receiving an RGB image signal and transmitting it to a printing unit according to the present modification. An image processing unit 1003 in the figure decodes a tracking pattern for an input RGB signal. If decoding here is successful, it is determined that a tracking pattern has been recorded in the input image, and the tracking signal 1006 is turned off. That is, if decoding is not possible, the tracking signal 1006 is turned off assuming that no tracking pattern has been recorded in the input image.
[0042]
If the input tracking signal 1006 is OFF, the multi-level processing unit 1004 does not input a tracking pattern for the input Y signal. Conversely, if the tracking signal 1006 is ON, a tracking pattern is added to the input Y signal.
With such a simple configuration, if a tracking pattern has already been added to an image input from a scanner or a host, the tracking pattern must not be entered at the time of printing, and the tracking pattern must be added to the input image. For example, a tracking pattern can be entered at the time of output.
[0043]
The present invention may be applied to a system including a plurality of devices or an apparatus including one device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus.
[0044]
【The invention's effect】
As described above, according to the present invention, it is possible to avoid difficulty in decoding a specific pattern and deterioration in image quality due to the pattern.
According to another aspect of the present invention, it is easy to specify an apparatus that has executed a printing process based on a model code unique to the color image recording apparatus.
[0045]
Further, according to another aspect, it is possible to prevent image quality deterioration of images other than the specific image.
[Brief description of the drawings]
FIG. 1 is a sectional configuration diagram of a color image recording apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a process of receiving an RGB image signal and transmitting the image signal to a printing unit in the embodiment.
FIG. 3 is a diagram illustrating a principle of printing a tracking pattern according to the embodiment.
FIG. 4 is a diagram illustrating a phase of a tracking pattern according to the embodiment.
FIG. 5 is a print example of a tracking pattern according to the embodiment.
FIG. 6 is a diagram for describing recognition and removal of a tracking pattern in the example.
FIG. 7 is a detailed block diagram of a multi-level processing unit 205.
FIG. 8 is a block diagram showing a signal system until an RGB image signal according to a first modification is transmitted to a printing unit.
FIG. 9 is a block diagram of a multi-level processing unit 805 according to a first modification.
FIG. 10 is a block diagram for explaining a process of transmitting an RGB image signal to a printing unit according to a second modification.
[Explanation of symbols]
201,801,1001 Host or scanner 202,803,1003 Image processing unit 203,804,1008 Color conversion processing unit 204 Encoding unit 205 Multi-value processing unit 206 ROM
208 External code signal 209 Internal code signal 210 Code signal

Claims (7)

In a color image recording apparatus that performs a predetermined printing process on a full-color image signal input from the outside,
Means for storing a model code unique to the image recording apparatus in advance,
Means for determining whether an external code is included in the image signal,
When said outer code is determined to include a removal means for removing the outer code from the image signal,
Means for generating a tracking code by combining the external code and a model code unique to the image recording apparatus ,
Means for adding the tracking code to the image signal from which the external code has been removed ,
Output means for printing out the image signal to which the tracking code is added ,
The color image recording apparatus , wherein the tracking code is combined so that the external code and a model code unique to the image recording apparatus can be determined from the tracking code . 2. The method according to claim 1, wherein the adding of the tracking code is performed only in the Y plane in the printing process for Y (yellow), M (magenta), C (cyan), and BK (black). 3. Color image recording device. 2. The color image recording apparatus according to claim 1, wherein the removal unit performs the removal by performing a predetermined operation on a pixel density related to the external code . 2. The color image recording apparatus according to claim 1, wherein when it is determined that the external code is not included in the image signal, the tracking code is a signal that matches a model code unique to the image recording apparatus. apparatus. The image processing apparatus further includes means for determining whether or not the image signal matches a specific image, wherein the removing means is provided when the image signal is not the specific image, and the image signal includes the external code. color image recording apparatus according to claim 1, characterized in that the removal of the external code. The color image recording apparatus according to claim 5, wherein the specific image includes securities . A color image recording method in a color image recording apparatus that performs a predetermined printing process on a full-color image signal input from the outside,
Storing a model code unique to the image recording apparatus in advance;
A step of determining whether an external code is included in the image signal,
If it is determined that the external code is included, removing the external code from the image signal,
A step of generating a tracking code by combining the external code and a model code unique to the image recording apparatus;
Adding the tracking code to the image signal from which the external code has been removed,
Printing out the image signal to which the tracking code is added,
A color image recording method, wherein the tracking code is combined so that the external code and a model code unique to the image recording apparatus can be determined from the tracking code .

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