JP2002077604A - Color image forming device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily identify a printer utilized for printing from printed matters. SOLUTION: In an image forming device for forming an image corresponding to image signals, pulse train signals VDO to draw dots based on the image signals are generated and provided to a composition part 414. Based on predetermined specific pattern representing an intrinsic number of the device, a tracking pattern generation part 410 outputs direction signals MKON or MKOFF to change the pulse width of a pulse corresponding to the drawing position of a specific pattern in the pulse train signals VDO. The composition part 414 changes the pulse width of pulse train signals VDO according to the direction signals MKON or MKOFF. A printer engine forms an image through drawing dots according to pulse train signals 416 with changed pulse width.

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 an image forming method for forming an image based on an image signal including a character code signal.

[0002]

2. Description of the Related Art In recent years, color printers have been used as various means of expression for users. In particular, color page printers are attracting attention because of their quietness, high-quality printing, and high-speed printing.

A multi-color light beam printer, which is one of the color page printers, is characterized in that a light beam is scanned on a photoreceptor in a main scanning direction to perform a first development, and then a photoreceptor on a transfer carrier. The step of transferring onto a recording medium such as recording paper is defined as the first step, and subsequently, the multicolor image is recorded in the second, third, and fourth steps.

Therefore, a method for recording a multicolor image will be described with reference to FIGS.

In FIG. 15, the photosensitive drum 201 rotating at a predetermined constant speed in the direction of the arrow in FIG.
4 is charged to a predetermined polarity and a predetermined voltage.
Next, the recording paper P is fed from the paper feed cassette 215 to the paper feed roller 2.
14 feeds the sheets one by one at a predetermined timing. Then, when the leading end of the recording paper is detected by the detector 202, the laser beam L modulated by the image signal VDO shown in FIG.
7 is emitted.

[0006] The laser beam L is scanned by the polygon mirror 207 and then guided onto the photosensitive drum 201 via the lens 208 and the mirror 209. A signal (hereinafter referred to as TOPSNS) from the detector 202 arranged at one end of the optical scanning is output to the image forming apparatus 250 (FIG. 16) as a vertical synchronization signal. The image signal VDO is the TOPS
In synchronization with a BD signal to be described later, following the NS signal,
Transmitted to laser 205. When the laser light L is incident on the detector 217, a beam detection signal (hereinafter, referred to as a BD signal) serving as a horizontal synchronization signal is output.

The polygon mirror 207 is a scanner motor 2
The scanner motor 206 is driven by the
Divider 2 that divides signal S1 from reference oscillator 220
The motor control circuit 225 controls the motor control circuit 225 to rotate at a predetermined constant speed according to the signal S2 from the control signal 25. The photosensitive drum 201 is scanned and exposed in synchronization with the BD signal, and then, after the first electrostatic latent image is developed by the developing device 203Y, a yellow first toner image is formed on the photosensitive drum 201. .

[0008] Immediately before the leading end of the recording paper P fed at a predetermined timing reaches the transfer start position, a predetermined transfer bias voltage having a polarity opposite to that of the toner is applied to the transfer drum 216. At the same time that one toner image is transferred to the recording paper P, the recording paper P is electrostatically attracted to the surface of the transfer drum 216.

Next, the laser light L
Scan forms a second electrostatic latent image, and the developing device 203M
As a result, the second electrostatic latent image is developed, and a magenta second toner image is formed on the photosensitive drum 201. Then, the second toner image is adjusted to the position of the first toner image previously transferred to the recording paper P, and is transferred onto the recording paper P. Note that the leading end of each color image is defined by the TOPSNS signal.

Similarly, a third electrostatic latent image is formed, developed by the developing device 203C, a cyan toner image is transferred to the recording paper P, and then a fourth electrostatic latent image is formed. Is formed, developed by the developing device 203K, and the black toner image is transferred to the recording paper P.

As described above, VD for one page is provided for each process.
O signals are sequentially output to the semiconductor laser 205. Further, the untransferred toner image is transferred to the cleaner 21 at each transfer step.
Scratched by 0.

Thereafter, when the leading end of the recording paper P onto which the four color toner images have been transferred approaches the position of the separation claw 212, the separation claw 212 approaches and comes into contact with the surface of the transfer drum 216.
The recording paper P is separated from the transfer drum 216. The leading end of the separation claw 212 has a rear end of the recording paper P
The transfer drum 216 is kept in contact with the transfer drum 216 until the transfer drum 216 separates, and then returns to the original position. Then, the charge accumulated on the recording paper P is removed by the charger 211 and the separation claw 212 is removed.
At the same time, the air discharge at the time of separation is reduced.

FIG. 17 shows the above-mentioned TOPSNS signal and VD
6 is a timing chart illustrating a relationship between O signals. In the figure,
A1 is a printing operation of the first color, A2 is a printing operation of the second color, A
Reference numeral 3 denotes a printing operation of the third color, and A4 denotes a printing operation of the fourth color. The sections A1 to A4 correspond to a one-page color printing operation.

FIG. 18 is a block diagram showing the general configuration of a general printer. As shown in the figure, a printer 302 receives a control signal and an image signal 307 from an external device, for example, a host computer 301, and a printer controller 303 provides a control signal 308 to a printer control unit 304. The image signal is provided to the laser driver 310 on the printer engine side via the image processing unit 305 in the printer controller 303, and drives the semiconductor laser 306.

FIG. 19 is a block diagram showing the internal configuration of the image processing unit 305 in FIG. An image processing unit 305 shown in FIG.
Each of the 8 bits, that is, a total of 24 bits of image signals is received.
The signal, C signal, or K signal is converted into the 8-bit VDO signal (FIG. 20 is a time chart at that time).

The Y, M, C, and K VDO signals are converted to a γ-corrected 8-bit signal by a γ correction unit 352 and then converted to a next-stage pulse width modulation unit 353 (hereinafter, referred to as a “pulse width modulation unit”).
PWM unit). In the PWM unit 353,
An 8-bit image signal is latched by an image clock iV at a latch 354.
The D / A converter 35
5 is converted to an analog voltage, and the analog comparator 3
Enter 56.

On the other hand, the image clock iVCLK is converted into a triangular wave by the triangular wave generator 358 and input to the analog comparator 356. This analog comparator 35
6 compares the above two signals, and as a result, outputs a PWM-processed image signal. Then, this output signal is inverted by the inverter 357, and a desired PWM signal 309 is obtained.

FIG. 21 is a time chart when the PWM unit 353 generates a PWM signal. As shown in the figure, when the 8-bit image data input to the PWM unit 353 is FF [H] (H indicates hexadecimal), the widest PWM signal is output. Data is 00
[H], the narrowest PWM signal is output.

[0019]

However, in the above-mentioned conventional color printer, high-quality printing can be performed by improving the printing performance, and accordingly, crimes caused by counterfeiting of securities such as banknotes are eliminated. There is a problem that is occurring frequently. In the future, it is expected that crimes of this kind will increase as the image quality of printers further increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus and an image forming method capable of easily determining a printer used for printing from a printed matter. is there.

[0021]

To achieve the above object, an image forming apparatus according to the present invention has the following arrangement. That is, an image forming apparatus that forms an image in accordance with an image signal, a generating unit that generates a pulse train signal for drawing a dot based on the image signal, and based on a predetermined specific pattern, The image processing apparatus includes: a change unit that changes a pulse width of a pulse corresponding to a drawing position of the specific pattern in the pulse train signal; and a drawing unit that forms dots by drawing dots in accordance with the pulse train signal changed by the change unit.

According to another aspect of the present invention, there is provided an image forming method for forming an image in accordance with an image signal, wherein a pulse train for drawing dots based on the image signal is provided. A generating step of generating a signal; a changing step of changing a pulse width of a pulse corresponding to a drawing position of the specific pattern in the pulse train signal based on a predetermined specific pattern; Drawing a dot in accordance with the generated pulse train signal to form an image.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below in detail with reference to the accompanying drawings.

[First Embodiment] FIG. 1 is a sectional view showing an entire image recording apparatus (color laser beam printer) as a color image forming apparatus according to an embodiment of the present invention.

In an image recording apparatus (hereinafter, referred to as an apparatus) shown in FIG.
Is held at the outer periphery of the transfer drum 103 with its leading end held between grippers 103f. Then, the latent images formed on the image carrier 100 for each color by the optical unit 107 are developed by the respective color developing units Dy, Dc, Dm, and Db, and are transferred to a sheet around the transfer drum 103 a plurality of times. A multicolor image is formed. Thereafter, the paper 102 is separated from the transfer drum 103, fixed by the fixing unit 104, and discharged from the discharge unit 105 to the discharge tray unit 106.

Here, each color developing device has a rotation support shaft at both ends thereof, and each developing device is held by the developing device selecting mechanism 108 so as to be rotatable around the axis. Each developing unit is shown in FIG.
As shown in (1), the rotation for selecting the developing device is performed with the posture kept constant. After the selected developing device is moved to the developing position, the developing device selecting mechanism 108 moves the selecting mechanism holding frame 109 in the direction of the image carrier 100 around the fulcrum 109b integrally with the developing device by the solenoid 109a. Positioning is performed.

Next, the operation of the image recording apparatus having the above configuration will be described.

First, the charger 111 shown in FIG.
The image carrier (photoconductor drum) 100 is uniformly charged to a predetermined polarity, and a first magenta latent image is formed on the photoconductor drum 100 by exposure with the laser beam L.
Then, in this case, only in the magenta developing device Dm,
A required developing bias voltage is applied to develop the magenta latent image, and a first toner image of magenta M is formed on the photosensitive drum 100.

On the other hand, the transfer paper P is fed at a predetermined timing, and immediately before the leading end of the transfer paper P reaches the above-described transfer start position, the transfer bias voltage (+1.8 KV) of the opposite polarity (eg, plus polarity) to the toner. Is applied to the transfer drum 103, the first toner image on the photosensitive drum 100 is transferred to the transfer paper P, and the transfer paper P is
3 is electrostatically adsorbed on the surface of the substrate. Then, the photosensitive drum 10
From 0, the remaining magenta toner is removed by the cleaner 112 to prepare for the formation of a latent image of the next color to be printed and the development process.

Next, a second cyan latent image 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 cyan developing unit Dc. Thus, a second toner image of cyan C is formed. Then, the second toner image of cyan C is transferred to the transfer sheet P in accordance with the position of the first toner image of magenta M previously transferred to the transfer sheet P. In the transfer of the second color toner image, a bias voltage of +2.1 KV is applied to the transfer drum 103 immediately before the transfer paper reaches the transfer portion.

Similarly, the third of yellow and black
A fourth latent image is sequentially formed on the photosensitive drum 100,
Each is sequentially developed by the developing devices Dy and Db. Then, the position is aligned with the toner image previously transferred to the transfer paper P, and the third and third colors of yellow and black are set. The fourth toner images are sequentially transferred. As a result, on the transfer paper P,
The four color toner images are formed in an overlapping state.

In the transfer of the third and fourth color toner images, bias voltages of +2.5 KV and +3.0 KV are applied to the transfer drum 103 immediately before the transfer paper reaches the transfer portion. The reason why the transfer bias voltage is increased each time the transfer of the toner image of each color is performed is to prevent a decrease in transfer efficiency.

The main cause of the decrease in the transfer efficiency is that when the transfer paper separates from the photosensitive drum 100 after the transfer, the surface of the transfer paper is charged to the opposite polarity to the transfer bias voltage by air discharge (the transfer paper is supported). This is because the surface of the transfer drum is slightly charged). This is because the charged charges are accumulated every transfer. When the transfer bias voltage is constant, the transfer electric field decreases every time the transfer is performed. .

In the transfer of the fourth color, when the leading edge of the transfer paper reaches the transfer start position (including immediately before and immediately after), an AC voltage of 5.5 KV (effective value, the frequency of which is 500 Hz) Then, a DC bias voltage of +3.0 KV having the same polarity and the same potential as the transfer bias voltage applied when transferring the toner image in the tray 4 is superimposed and applied to the charger 111.

The reason why the charger 111 is operated when the leading edge of the transfer paper reaches the transfer start position during the transfer of the fourth color is to prevent transfer unevenness. In particular, in the transfer of a full-color image, even if slight transfer unevenness occurs, it is easy to notice as a color difference, and it is necessary to apply a required bias voltage to the charger 111 to perform a discharge operation as described above. Becomes

Thereafter, when the leading end of the transfer paper P on which the four color toner images have been superimposed and transferred approaches the separation position, the separation claw 113 is moved.
Approach, the leading edge thereof comes into contact with the surface of the transfer drum 103, and the transfer paper P is separated from the transfer drum 103. The leading end of the separation claw 113 keeps contact with the surface of the transfer drum 103 until the rear end of the transfer pattern P leaves the transfer drum 103, and thereafter returns to the original position when it is separated from the transfer drum 103.

The charger 111 transfers the transfer paper P as described above.
When the leading end of the transfer paper reaches the transfer start position of the final color, the trailing edge of the transfer paper operates until it leaves the transfer drum 103 to remove the accumulated charge (the opposite polarity to the toner) on the transfer paper, and the separation claw 113 In addition to facilitating separation of the transfer paper, air discharge during separation of the transfer paper is reduced.

When the rear end of the transfer paper reaches the transfer end position (the exit of the nip formed by the photosensitive drum 100 and the transfer drum 103), the transfer bias voltage applied to the transfer drum 103 is turned off. (Ground potential). At the same time, the bias voltage applied to the charger 111 is turned off.

The transfer paper P thus separated is then conveyed to a fixing device 104, where the toner image on the transfer paper is fixed, and then discharged onto a discharge tray 115.

Next, the operation of laser beam scanning in the apparatus according to this embodiment will be described.

The optical unit 107 shown in FIG. 1 includes a semiconductor laser 120, a polygon mirror 121, and a scanner motor 12.
2, a lens 123 and a mirror 125. Then, when the recording paper P is fed and the leading edge thereof is detected, the image signal VDO for one page is synchronized with the detection.
Is output to the semiconductor laser 120.

The light beam L is modulated by the image signal VDO and is emitted toward the polygon mirror 125 rotated by the scanner motor 122 so that the lens 123
The light is guided to the photosensitive drum 100 by the mirror 125. When the light beam L is emitted, the light beam L is detected by a detector (not shown) arranged on the scanning axis, and a beam detection signal BD serving as a horizontal synchronization signal is output. As a result, the photosensitive drum 100 is scanned and exposed by the light beam L in synchronization with the BD signal, and an electrostatic latent image is formed.

FIG. 2 is a block diagram showing a schematic configuration of the apparatus according to this embodiment. As shown in FIG. 1, a printer 2 is a printer controller 3 that develops image information in a predetermined description language sent from a host computer 1.
And a printer engine including a printer control unit 404 and a signal processing unit 402. The host computer 1 also sends bit data such as RGB read by an image reader or the like. Printer controller 3
The image processing unit 401 converts the RGB image into a YMCK image, performs pulse width modulation or dither processing on the multi-valued YMCK image, and generates a 1-bit VDO signal 6.
Since this processing has been described in detail with reference to FIG. 18, the description will be omitted here.

FIG. 3 is an internal block diagram of the printer controller 3. As shown, an image developing unit 406 for converting printer language information sent from the host computer 1 into bitmap data, a page memory unit 407 for storing the data for one page, and RGB sent from the page memory unit 407 Information is converted to YMCK information, and the VD converted to a pulse width corresponding to the multi-valued density is obtained.
The image processing unit 401 generates the O signal 6.

FIG. 4 is a time chart showing the VDO signal 6 sent from the printer controller 3, the BD signal 423 which is a horizontal synchronization signal sent from the engine to the printer controller, and the PSYNC signal 424 which is a vertical synchronization signal. . As shown, the PSYNC signal 42
4 in synchronization with magenta data, cyan data, yellow data, and black data.

FIG. 5 is an internal block diagram of the signal processing unit 402 on the engine side. The VDO signal 6 sent from the printer controller 3 is sent to a laser driver (not shown) via a synthesizing unit 414 and an AND circuit 415. The image mask signal generation unit 411 generates a MASK signal 419 which is a control signal for forcibly turning off the laser outside the printing area. The MASK signal is "1" except for the print area, and "0" is the print area. The MASK signal is generated by receiving desired information from the CPU 412,
And a PSYNC signal.

The tracking pattern generating section 410 prints
This is a block for generating a signal for printing dots representing machine-specific numbers with yellow toner that is difficult to see. The code is represented by the arrangement of this tracking pattern on the printed matter. The generator 410 includes a clock signal CCLK output from a crystal oscillator 413 disposed on the engine side, a BD signal 423, and a PSYNC signal 42.
4 and generates a signal MKON for designating printing at a density higher than the original image density and a signal MKOFF for designating printing at a density lower than the original image density.
Note that the arrangement information 42I of this tracking pattern is stored in the CPU 412.
Is given to the tracking pattern generation unit 410. CPU 412
Reads the machine-specific number stored in the memory 420, encodes the number, and arranges the tracking pattern arrangement information 421.
Generate

The tracking pattern is added to the VDO signal 6 when printing the yellow plane, and is not added to the planes of other colors. Therefore, a color signal indicating at least whether or not the color currently being recorded is yellow is input to the tracking pattern generation unit 410, and if yellow is not currently recorded, MKON and MKOFF are set to “0”. (See FIG. 6).

FIG. 6 is an internal block diagram of the tracking pattern generator 410. Clock CCL of crystal oscillator 413
The frequency of K is the same as the image transfer rate of the printer controller. The CCLK signal is supplied to the multiplication circuit 4
At 34, the frequency is converted to 8 times. The clock signal 445 whose frequency has been multiplied by eight is divided by a frequency divider 435 into a BD signal.
The clock P synchronized with the BD signal at the same frequency as the crystal oscillator 413 in synchronization with the rising edge of the signal 423
CLK. This situation is shown in the time chart of FIG. 7 (FIG. 7 is a time chart illustrating the generation of PCLK according to the present embodiment).

Reference numeral 426 denotes an image clock PC in the main scanning direction.
This is a 4-bit counter that counts LK, starts after being reset by the BD signal 423, and repeatedly counts from 0h to Bh. This indicates that the counter 426 counts 12 pulses (PCLK). As will be described later, the tracking pattern of the present embodiment uses 12 print dots in the horizontal direction. A 5-bit counter 427 counts the BD signal 423 in the sub-scanning direction. The counter 427 starts after resetting with the PSYNC signal 424 and repeatedly counts from 0h to 1Fh. This means that the counter 427 counts 32 pulses (BD). As will be described later, this is because the tracking pattern of the present embodiment uses 32 lines in the vertical direction. The output signals 446 of these counters are information indicating the coordinates of the print dots, and when the matching circuits 428 and 429 at the next stage determine that they are at the desired coordinate positions, the matching signals 447 and 4 are output.
48 is set to “1”. Flip-flop circuits 432, 4
Reference numeral 33 serves to synchronize the coincidence signals 447 and 448 with the PCLK 425. If the color signal indicates that the current print color is other than yellow, the flip-flop circuits 432 and 433 are reset, and the MKO
"0" is output for both N and MKOFF.
It should be noted that it is apparent that various modifications can be applied to not to combine the tracking patterns at the time of printing other than yellow, without being limited to the above method.

The basic pixels of the tracking pattern are arranged such that dots printed at a higher density than the original image density are sandwiched between dots to be lightened. By arranging the tracking pattern base at a predetermined position, predetermined information is expressed.

The coordinates 437 and 438 for printing the tracking pattern set in the matching circuits 428 and 429 are set in advance by a CPU (not shown).

FIG. 8 is a diagram schematically showing an area of a unit representing a machine-specific number in a tracking pattern. As shown in the figure, a predetermined code is expressed by nine patterns in a region within a broken line, and two patterns among them are reference patterns. “0” to “3” (2
(7 bits) (7 digits), and a total of 14 bits are expressed by 7 patterns. 0 when converted to decimal
The numbers are from number 16383 to number 16. FIG. 8 represents the number 11384. This pattern is repeated in the main scanning direction and the sub-scanning direction.

FIG. 9 is a diagram showing a circuit example of the synthesizing unit 414 shown in FIG. In this circuit, the tracking pattern generator 4
10 output signals MKON417 and MKOFF4
In response to 18, the ON time (HIGH section) of the VDO signal 6 sent from the controller is increased or decreased.

The VDO signal 6 is input to the A0 pin of the selector 504 and, at the same time, to the delay circuit 507.
The signal delayed by this delay circuit 507 is
2 and input to the AND circuit 503. An output signal of the OR circuit 502 has a delay time Td [n generated by the delay circuit 507.
S], and outputs a VDO signal whose pulse width is increased by [S].
The output signal of the AND circuit 503 outputs a VDO signal whose pulse width is shortened by the delay time Td [nS] generated in the delay circuit. Seleta 504 is one of the above three signals.
Select and output one signal.

FIG. 10 is a diagram showing the selection logic of the selector 504. That is, when both MKON and MKOFF are 0, the signal at the terminal A0 is selected and the VDO signal is used as it is. When MKON is 1, the signal A1 is selected, and a VDO signal having a pulse width longer by the delay time Td is used. Further, M
If KOFF is 1, the signal at terminal A2 is selected and
A VDO signal whose pulse width is shortened by the delay time Td is used. FIG. 11 is a timing chart showing this state.

FIG. 12 shows an example of the tracking signals MKON 417 and MKOFF 418 generated by the present circuit. In the figure, when MKON = LOW and MKOFF = LOW, printing is performed with the VDO signal 6 which is the original image signal, and MKO is performed.
When N = HIGH and MKOFF = LOW, the VDO signal 6 as the original image signal is fattened for a predetermined time and printed.
When MKON = LOW and MKOFF = HIGH, it indicates that the VDO signal 6 which is the original image signal is to be printed by narrowing for a predetermined time. In this tracking pattern, three dots are set as one reference dot and printed every four lines.

FIG. 13 is an image diagram in which the tracking pattern shown in FIG. 12 is mixed with the image signal VDO6 and printed. This figure is printed when the phase of the pixel clock of the VDO data 6 output from the printer controller coincides with the phase of the pixel clock of the input tracking pattern, that is, the synchronization of the two clocks described above. FIG. In this case, the VDO signal of the original image is printed with a uniform intermediate density.

As a modification of this embodiment, a frequency of the crystal oscillator provided in the engine may be different from the image transfer rate of the controller. In the case of a crystal oscillator having a frequency several times the image transfer rate, a multiplication circuit 4
34 becomes unnecessary. Alternatively, the frequency may be lower than the image transfer rate, and a clock of a desired frequency may be generated by the multiplying circuit 434.

In this embodiment, the MKON signal, M
Both KOFF signals have the same size as one dot,
It may be larger than one dot. That is, MKON and MKOFF may be applied over a plurality of dots.

Further, the PCL output from the frequency divider 435
K may be completely different from the image transfer rate. In this case, the size and the interval of the tracking pattern dots are different from the integral multiple of the image dots. When a code is extracted from the position of the tracking pattern dot, it is determined not as an absolute size but as a print interval ratio, so that it is established.

Also, in FIG. 5, ORing section 414, tracking pattern generating section 410, image mask generating section 411 and OR
The circuit 415 may be included in the ASIC.

As described above, according to the first embodiment, it is possible to print a printer-specific code on printed matter in such a manner that it is difficult to see the code, and forgery of securities such as banknotes using the printer can be performed. In this case, the printer used for forgery can be specified from the printed matter.

[Second Embodiment] FIG. 14 shows a second embodiment of the present invention.
FIG. 13 is a diagram illustrating a circuit example of a synthesis unit 414 according to the embodiment. The difference from the first embodiment (FIG. 9) is that the delay circuit 5
07 is that a flip-flop is used.
The flip-flops 509 and 510 receive a clock signal x8PCLK 445 having a frequency eight times that of PCLK, and delay the VDO signal 6 by a time corresponding to １ ／ cycle of PCLK.

According to the second embodiment, since the delay time can be controlled by the clock, it is possible to stably delay.

In this embodiment, the recording order is magenta, cyan, yellow, and black. However, the present invention is not limited to the recording order of the color components, and other recording orders, for example, Y → M → C → Bk It can be in order. Note that the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but a device including one device (for example, a copying machine, a facsimile machine, etc.). May be applied.

[0067]

As described above, according to the present invention,
From the printed matter, the printer used for the printing can be easily determined. For this reason, for example, it is possible to print the code unique to the printer on printed matter so that it is difficult to see the code. For example, when forged securities such as banknotes are used using the printer, the printed matter is forged. The printer used for can be easily specified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an entire image recording apparatus as a color image forming apparatus according to an embodiment.

FIG. 2 is a block diagram illustrating a schematic configuration of an apparatus according to the embodiment.

FIG. 3 is an internal block diagram of the printer controller 3.

FIG. 4 is a time chart showing a VDO signal 6 sent from the printer controller 3, a BD signal 423 as a horizontal synchronization signal sent from the engine to the printer controller, and a PSYNC signal 424 as a vertical synchronization signal.

FIG. 5 is an internal block diagram of a signal processing unit 402 on the engine side.

FIG. 6 is an internal block diagram of the tracking pattern generation unit 410.

FIG. 7 is a time chart illustrating generation of PCLK according to the embodiment.

FIG. 8 is a diagram schematically showing a unit area representing a machine-specific number in a tracking pattern.

FIG. 9 is a diagram illustrating a circuit example of a combining unit 414 illustrated in FIG. 4;

FIG. 10 is a diagram illustrating selection logic of a selector 504.

FIG. 11 is a timing chart showing this state.

FIG. 12 shows MKON4 which is a tracking signal generated by this circuit.
FIG. 17 is a diagram showing an example of MKOFF418.

FIG. 13 shows the tracking pattern shown in FIG.
FIG. 11 is an image diagram in which O6 is mixed and printed.

FIG. 14 shows a synthesizing unit 414 according to the second embodiment of the present invention.
FIG. 3 is a diagram illustrating a circuit example of FIG.

FIG. 15 is a diagram illustrating the configuration and operation of a general color printer.

FIG. 16 is a diagram illustrating the configuration and operation of a general color printer.

FIG. 17 is a timing chart showing the relationship between the TOPSNS signal and the VDO signal.

FIG. 18 is a block diagram illustrating an overall configuration of a general printer.

19 is a block diagram illustrating an internal configuration of an image processing unit 305 in FIG.

FIG. 20 is a time chart illustrating an operation of the image processing unit illustrated in FIG. 19;

FIG. 21 is a time chart when a PWM signal is generated by a PWM unit 353.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2C061 AP03 AP04 AQ06 AR01 AS02 CL10 2C087 AA03 AA09 AA13 AA15 AA16 AC08 BA03 BA07 BA12 BD07 DA13 5C074 AA11 BB03 BB17 DD01 DD07 DD24 DD28 EE02 FF15 HH02 MP0733PP14 PP PP66 PQ05 PQ08 PQ12 RR10 TT03

Claims (15)

[Claims] 1. An image forming apparatus for forming an image according to an image signal, comprising: a generation unit configured to generate a pulse train signal for drawing dots based on the image signal; Changing means for changing a pulse width of a pulse corresponding to a drawing position of the specific pattern in the pulse train signal; drawing means for forming a dot according to the pulse train signal changed by the changing means to form an image; An image forming apparatus comprising: 2. The image signal according to claim 1, wherein the image signal is a multi-valued image signal, and wherein the generating unit generates a pulse train signal having a pulse width modulated in accordance with the multi-valued image signal. Image forming apparatus. 3. The method according to claim 1, wherein the change unit includes an instruction signal generating unit that generates an instruction signal for instructing a pulse width change based on the specific pattern, and changes the pulse width of the pulse train signal based on the instruction signal. The image forming apparatus according to claim 2, wherein: 4. The method according to claim 1, wherein the changing unit includes a delay circuit that delays the pulse train signal to generate a delayed pulse train signal; a normal pulse signal obtained from the pulse train signal based on the specific pattern; Means for selecting and outputting, based on the instruction signal, either a narrow pulse signal obtained by a logical product with the delayed pulse train signal or a wide pulse signal obtained by a logical sum. The image forming apparatus according to claim 3. 5. The image forming apparatus according to claim 3, wherein the drawing of the specific pattern is performed using a plurality of dots whose widths are changed as one unit. 6. The image forming apparatus according to claim 5, wherein the drawing of the specific pattern uses three dots each having a wide pulse signal sandwiched between narrow pulse signals as one unit. 7. The image forming apparatus according to claim 1, wherein the specific pattern includes information unique to the apparatus. 8. The image forming apparatus according to claim 4, wherein said instruction signal generating means and said delay circuit are configured in the same integrated circuit. 9. An image forming method for forming an image according to an image signal, comprising: a generating step of generating a pulse train signal for drawing dots based on the image signal; A changing step of changing a pulse width of a pulse corresponding to a drawing position of the specific pattern in the pulse train signal; and a drawing step of forming dots according to the pulse train signal changed in the changing step to form an image. An image forming method comprising: 10. The image signal according to claim 9, wherein the image signal is a multi-level image signal, and wherein the generating step generates a pulse train signal whose pulse width is modulated according to the multi-level image signal. Image forming method. 11. The changing step includes an instruction signal generating step of generating an instruction signal for instructing a pulse width change based on the specific pattern, and changing a pulse width of the pulse train signal based on the instruction signal. The image forming method according to claim 10, wherein: 12. The changing step includes a step of generating a delayed pulse train signal by delaying the pulse train signal; a normal pulse signal obtained from the pulse train signal based on the specific pattern; Selecting and outputting either a narrow pulse signal obtained by a logical product with the delayed pulse train signal or a wide pulse signal obtained by the logical sum based on the pulse width change signal. The image forming method according to claim 11, wherein 13. The image forming method according to claim 11, wherein the drawing of the specific pattern is performed using a plurality of dots whose widths are changed as one unit. 14. The drawing of the specific pattern is performed by dividing three dots in which a wide pulse signal is sandwiched between narrow pulse signals.
14. The image forming method according to claim 13, wherein the unit is a unit. 15. The image forming method according to claim 9, wherein the specific pattern includes device-specific information.