JPH0687235A - Informaiton recorder - Google Patents

Abstract

PURPOSE:To perform an optimum smoothing correction in accordance with a curvature of a profile part of a character or graphic form. CONSTITUTION:Line memories 1a, 1b,...1k,...9k store dot information of a main scanning length for a page to be printed. A processing circuit 43 detects the feature of data stored in a dot matrix memory for conducting smoothing and changes a target pixel 5f as required. The processing circuit 43 outputs a parallel signal MDT after detecting the feature of the data stored in the dot matrix memory 11 dots in a main scanning direction by 9 dots in a subscanning direction and outputted from shift registers and changing a target pixel 5f as required. A parallel-serial conversion circuit 44 converts the inputted parallel signal MDT to a serial signal VDOM and, thereafter, drives a semiconductor laser by a laser driver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording apparatus such as a laser beam printer, and more particularly to smoothing and printing bitmap data representing characters and figures to perform smoothing correction of the contours of the printed characters and figures. The present invention relates to an information recording device that enhances print quality.

[0002]

2. Description of the Related Art In recent years, a laser beam printer using electrophotographic technology has been used in an output device of a computer, an output unit of a facsimile machine, or a so-called digital copying machine for printing image data read from an image scanner. ing. The laser beam printer used for these prints at a resolution of 300 dots / inch, for example, as shown in FIG. In this case, characters and figures are drawn and printed by black dots (● marks) and white dots (◯ marks) at positions arranged on a grid of 300 dots / inch. In addition, the figure shows the alphabet "a".
The dot arrangement interval is about 85 microns at a resolution of 300 dots / inch.

Generally, it is said that a person can visually confirm up to about 20 microns, but in comparison with this, at the above resolution (about 85 microns), the outline of a character or a figure formed by dots is compared. The parts look jagged and are not necessarily high quality prints. Therefore, in order to solve this problem, there are the following approaches. The first approach is to simply increase the resolution (eg 1200 dots / inch). However, this method has a disadvantage that 4 × 4 = 16 times as many bit map memories are required to represent the same area, and the apparatus becomes very expensive.

As a second approach, by adding a small amount of buffer memory without increasing the capacity of the bitmap memory, the dot data around the pixel of interest to be printed is referred to and the print data of the pixel of interest is printed. There is a method of equivalently increasing the resolution in the main scanning direction or in the main scanning direction and the sub scanning direction by modulating. As prior art (prior application patent) related to this method, US Pat. No. 4,437,122 (Xerox Co.) US Pat. No. 4,700,201 (Ricoh Co.) US Pat. No. 4,847,641 ( Hewlett-Packard Company).

[0005]

Among the above-mentioned conventional techniques,
The techniques described in U.S. Pat. No. 4,437,122 (Xerox Co.) and U.S. Pat. No. 4,700,201 (Ricoh Co., Ltd.) refer only to a pixel of interest and eight pixels around the pixel of interest. Then, the target pixel to be printed is corrected.

However, in this type of method, since the reference area of the surrounding pixels is narrow, it can be confirmed that the pixel of interest is a part of the curve, but to what extent the curvature is a part of the curve. Can't be confirmed. In particular, it is difficult to optimize the smoothing effect because it is not possible to detect contours that are nearly horizontal or contours that are nearly vertical, and it is not possible to perform appropriate correction according to the curvature. There is.

On the other hand, the technique described in US Pat. No. 4,847,641 (Hewlett-Packard Co.) refers to peripheral pixels in a wider area than the above two techniques, and therefore, to what extent the target pixel is It is also possible to confirm whether it is a part of a curve with a curvature of. However, in this technique, although the reference target area is wide, each matching pattern that is matched individually refers only to a part of the reference target area. There are disadvantages as shown in. That is, (1) it is impossible to identify whether or not the pixel of interest is a part of a binarized halftone image such as a dither image or an image by an error diffusion method. Therefore, although the smoothing effect on the character image can be improved, a part of the dots forming the halftone image by the dither image or the error diffusion method may be erroneously smoothed.

For example, FIG. 48 (a) is a diagram in which a part of a 4 × 4 dither image is taken out. In FIG. 48 (a), if a peripheral limited area is referred to with respect to the target pixel 5f, The pixel of interest is recognized as a character or a part of a figure. As a result, the image density is locally changed in the halftone image, and there is a high possibility that the image quality is deteriorated, for example, a pseudo contour is generated.

(2) It cannot be discriminated whether or not the pixel of interest belongs to a part of the image in which the images are dense (congested). For example, FIG. 48B is an example of an image composed of a dense line group of 1 dot line. In this case, the pixels for which the dot density needs to be changed in order to smooth each line are the pixels marked with “Δ” or “x” shown in FIG. 48 (c). Then, as can be seen from the figure, the changed pixel is adjacent to or close to the pixel to be changed, which lowers the resolution of the image. Such complicated pixel crowding may occur not only when line drawings are crowded but also for small-sized characters and Chinese characters.

In such a case, the target pixel changed for smoothing comes close to the changed pixel for the adjacent image, and the pixel (line or character side) is changed.
And adjacent pixels are not clearly identified, and as a result, the resolution (resolution) of the image around the part is extremely reduced and the image becomes blurry, or "moire" occurs in the image. Image quality may be deteriorated.

Further, when a pixel is expressed in halftone within one pixel for smoothing in a portion where such an image is dense, the reproduction of the density becomes unstable due to the interaction of neighboring pixels, and the temperature reproduction becomes unstable. It becomes more susceptible to environmental changes such as humidity and humidity. Then, the smoothing effect changes depending on the environment, so that there occurs a problem that the character shape looks like a different font each time it is printed.

It should be noted that the reference area of each matching pattern may be made sufficiently wide so that it can be discriminated whether or not the pixel of interest belongs to the dither image or the dense portion of the image. The effect of simplifying the target processing circuit is lost. It is an object of the present invention to provide an information recording apparatus that performs optimum smoothing correction according to the curvature of the outline portion of a character or a figure and improves deterioration of a halftone image.

[0013]

To achieve the above object, the present invention forms an electrostatic latent image on a recording medium with a light beam modulated according to an information signal, and forms the electrostatic latent image on the recording medium. In an information recording apparatus for visualizing and recording information, a means for storing a dot data group consisting of a plurality of predetermined bit information, a means for extracting characteristics of a dot pattern in a peripheral region of a target pixel, When the dot data in the dot data group and the dot pattern match, the pixel information changing means for changing the print information corresponding to the target pixel based on the dot data.

[0014] Preferably, the pixel information changing means arranges print areas independent of the main scanning direction in an area obtained by dividing the target pixel in the main scanning direction and the sub-scanning direction. Further, preferably, the pixel of interest changed by the pixel information changing means is composed of a section having a double resolution in the sub scanning direction and a four or eight resolution in the main scanning direction.

[0015]

With the above arrangement, it functions to improve the image quality deterioration of the halftone image.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. [First Embodiment] The first embodiment according to the present invention will be described below. <Description of Engine Unit of Laser Beam Printer> FIGS. 1 and 2 are diagrams showing a configuration of an engine unit of a laser beam printer according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a recording medium,
A paper cassette 2 holds the paper 1. 3 separates only the uppermost one of the papers 1 placed on the paper cassette 2, and the leading end of the separated paper is fed by the drive means (not shown) to the feed rollers 4, 4 '. It is a paper feed cam that conveys to a position, and intermittently rotates every time paper is fed, and feeds one sheet corresponding to one rotation.

Reference numeral 18 denotes a reflection type photo sensor, which detects the paper absence by detecting the reflected light of the paper 1 through a hole 19 provided at the bottom of the paper cassette 2. Also,
The paper feed rollers 4 and 4'roll the paper by the paper feed cam 3.
When the paper 1 is conveyed to the la section, the paper 1 is rotated while being lightly pressed, and the paper 1 is conveyed. Then, when the sheet 1 is conveyed and the leading end of the sheet 1 reaches the position of the registration shutter 5, the sheet 1 is stopped by the registration shutter 5, and the sheet feeding rollers 4 and 4 ′ are moved relative to the sheet 1. The carrier torque is generated while slipping and continues to rotate.

In this case, by driving the registration solenoid 6 to release the registration shutter 5 in the upward direction, the sheet 1 is fed to the transport rollers 7, 7 '. The driving of the resist shutter 5 is synchronized with the transmission timing of the image formed by the laser beam 20 being formed on the photosensitive drum 11. 2
A font sensor 1 detects whether or not the paper 1 is present at the location of the resist shutter 5.

A rotary polygon mirror 52 is driven by a motor 53. The laser beam 20 from the semiconductor laser 51 driven by the laser driver 50 (see FIG. 2) is scanned in the main scanning direction by the rotating polygon mirror 52, and is arranged between the rotating polygon mirror 52 and the reflection mirror 54. It is guided to the photosensitive drum 11 via the reflection mirror 54 via the f-θ lens 56. And the photosensitive drum 1
The laser beam imaged on 1 is scanned in the main scanning direction,
A latent image is formed on the main scanning line 57.

At this time, if the printing density is 300 dots / inch and the printing speed is 8 sheets / minute (A4 size or letter size), the laser lighting time for recording one dot is about 540 nanoseconds. Further, the laser lighting time for recording one dot at a printing density of 300 dots / inch and a printing speed of 16 sheets / minute is about 270 nanoseconds. Further, when the printing density is 600 dots / inch and the printing speed is 8 sheets / minute, the laser lighting time for recording 1 dot is about 13 nanoseconds.
When the printing density is 600 dots / inch and the printing speed is 16 sheets / minute, the laser lighting time for recording one dot is about 68 nanoseconds.

The driving capability of the laser driver 50 used in this type of laser beam printer is about 4 nanoseconds (lighting rise time is about 1 nanosecond, extinction fall time is about 1 nanosecond) as a pulse lighting time. It is the limit. Therefore, even if it is attempted to turn on the light in a cycle shorter than this, the light cannot be turned on, or even if the light is turned on, the lighting time and the amount of lighting light become unstable. Therefore, the laser lighting pulse width modulated for smoothing should be at least about 4 nanoseconds or more in lighting time.

Further, as shown in FIG.
Beam detector 55 arranged at the scanning start position of 0
Detects a beam detect (BD) signal as a synchronization signal for determining the image writing timing in the main scanning direction by detecting the laser beam 20. After that, the paper 1 is fed by the transport rollers instead of the paper feed rollers 4, 4 '.
The transfer torque is obtained by the rollers 7 and 7 ′ and is sent to the photosensitive drum 11. Then, a latent image is formed on the surface of the photosensitive drum 11 charged by the charger 13 by the exposure of the laser beam 20. After the latent image of the portion exposed by the laser beam is visualized as a toner image by the developing device 14,
The transfer charger 15 transfers the toner image onto the paper surface of the paper 1. A cleaner 12 cleans the drum surface after the transfer onto the paper 1.

The sheet 1 on which the toner image is transferred is then
The toner image is fixed by the fixing rollers 8 and 8 ', and the paper is discharged onto the paper discharge tray 10 by the discharge rollers 9 and 9'. Further, reference numeral 16 denotes a paper feed table, which enables not only paper feed from the paper cassette 2 but also manual paper feed from the paper feed tray 16 one by one. The paper that has been manually fed to the 17-fold manual feed roller on the paper feed tray 16 is
Lightly pressed by the manual paper feed roller 17, and the leading edge of the paper is the registration shutter 5 as in the above paper feed rollers 4 and 4 '.
It is transported until it reaches, and slips and rotates there. The subsequent transport sequence is exactly the same as when feeding paper from a cassette.

The fixing roller 8 contains a fixing heater 24, and the surface of the fixing roller 8 is detected based on the temperature detected by the thermistor 23 which makes a slip contact with the roller surface of the fixing roller 8. The toner image on the paper 1 is thermally fixed by controlling the temperature to a predetermined temperature. A photo sensor 22 detects whether or not there is a sheet at the position of the fixing rollers 8 and 8 '.

The printer configured as described above is connected to the controller through an interface, receives a print command and an image signal from the controller, and performs a printer sequence. Therefore, a signal transmitted / received via this interface will be briefly described below. <Signal Between Controller and Printer> FIG. 3 is a diagram showing an interface signal between the printer engine section and the controller for generating image data. Hereinafter, each interface signal shown in the figure will be described.

<PPRDY signal> This is a signal sent from the printer to the controller, and is a signal notifying that the printer is in an operable state after the printer is powered on. <CPRDY signal> This signal is sent from the controller to the printer, and is a signal notifying that the controller is powered on and the controller is in an operable state.

<RDY signal> This is a signal sent from the printer to the controller, and indicates that the printer is ready to start the printing operation or is ready to continue if it receives the PRNT signal described later. It is a signal. For example, when the printing operation cannot be executed, such as when the paper cassette 2 is out of paper, this signal is "false".

<PRNT signal> This is a signal sent from the controller to the printer and is a signal for instructing to start the print operation or to continue the print operation. When the printer receives this signal, it starts the printing operation. <VSREQ signal> This is a signal sent from the printer to the controller and is an RD sent from the printer.
When the Y signal is in the "true" state, PRN is sent from the controller.
By setting the T signal to "true", this is a signal indicating that the printer is ready to receive image data after the instruction to start the printing operation is sent. In this state, it becomes possible to receive the VSYNC signal described later.

<VSYNC signal> This signal is sent from the controller to the printer and is a signal for synchronizing the sending timing of image data in the sub-scanning direction. Due to this synchronization, the toner image formed on the drum is transferred onto the paper in synchronization with the paper in the sub-scanning direction. <BD signal> This signal is sent from the printer to the controller and is a signal for synchronizing the sending timing of image data in the main scanning direction. Due to this synchronization, the toner image formed on the drum is transferred onto the paper in synchronization with the paper in the sub-scanning direction. This signal indicates that the scanning laser beam is at the starting point of main scanning.

<VDO signal> This signal is sent from the printer to the controller and is a signal for sending image data to be printed. This signal is V
It is transmitted in synchronization with the CLK signal. The controller receives code data such as a PCL code transmitted from the host device and generates a character bit signal generated by a character generator corresponding to the code data. It also receives a vector code such as a post-crypto code transmitted from the host device, generates graphic bit data corresponding to this code, or generates bitmap data read from an image scanner, and outputs this data to the printer as a VDO signal. Send. The printer sends this signal
A true image is printed as a black image, and a false signal is printed as a white image.

<VCLK signal> A signal sent from the controller to the printer, which is a synchronization signal for transmitting and receiving the VDO signal. <SC signal> A bidirectional serial signal for bidirectionally transmitting and receiving a "command" which is a signal sent from the controller to the printer and a "status" which is a signal sent from the printer to the controller. The SCLK signal described later is used as a synchronization signal when transmitting or receiving this signal. Further, as a signal for controlling the transmission direction of the bidirectional signal, an SBSY signal and a CB which will be described later
The SY signal is used.

Here, the "command" is a serial signal consisting of 8 bits, and for example, the paper feed mode is
This is command information for the controller to instruct the printer whether it is the mode of feeding from the cassette or the mode of feeding from the manual feed port. Also,"
"Status" is a serial signal composed of 8 bits. For example, the temperature of the fixing device of the printer is in a wait state where it does not reach a printable temperature, or a paper jam condition or a paper cassette is out of paper. Is information for informing the controller of various states of the printer.

<SCLK signal> Printer sends "command"
Is a sync pulse signal for fetching the signal, or for the controller to fetch the "status". <CBSY signal> This is a signal for occupying the SC signal and the SCLK signal before the controller signals the "command". <SBSY signal> This is a signal for occupying the SC signal and the SCLK signal before the printer transmits the "status".

After the VDO signal is input to the printer together with the VCLK signal, it is input to a VDO signal processing unit 101, which will be described later, provided in the printer engine. The VDO signal processing unit performs signal conversion of the input VDO signal by signal processing described later, and converts the signal into a converted signal VDO.
M is input to a laser driver (not shown) to drive the semiconductor laser 51 to blink. <Operation of Interface> The operation of the above interface will be described below.

When the power switch of the printer is turned on and the power switch of the controller is turned on, the printer initializes the internal state of the printer and then sets the PPRDY signal to "true" for the controller. Similarly, the controller initializes the internal state of the controller and then sets the CPRDY signal to "true" for the printer.
With this, the printer and the controller confirm that the respective power supplies have been turned on.

After that, the printer causes the fixing rollers 8 and 8 '.
The fixing heater 24 housed inside is energized to fix the fixing roller.
When the surface temperature of the toner reaches a temperature at which fixing is possible, the RDY signal is set to "true". The controller sends the RDY signal
After confirming that the PRNT signal is "true" when there is data to be printed, the printer confirms that the PRNT signal is "true". At the same time as rotating the photosensitive drum 11 to uniformly initialize the potential on the surface of the photosensitive drum,
In the cassette paper feed mode, the paper feed cam 3 is driven to convey the leading edge of the paper to the position of the registration shutter 5.

In the manual feed mode, the manual feed roller 17 conveys the paper manually fed from the paper feed table 16 to the position of the resist shutter 15. After that, when the printer becomes ready to accept the VDO signal, the VSREQ signal becomes "true". The controller is
After confirming that the VSREQ signal is "true",
At the same time that the YNC signal is set to "true", the VDO signal is sequentially transmitted in synchronization with the BD signal. Also, the printer is VS
When it is confirmed that the YNC signal becomes "true", the registration solenoid 6 is driven in synchronization with this and the registration shutter 5 is released. As a result, the sheet 1 is conveyed to the photosensitive drum 11.

In response to the VDO signal, the printer turns on the laser beam when the image should be printed black and turns off the laser beam when the image should be printed white, thereby forming a latent image on the photosensitive drum 11. Form and develop 1
At 4, toner is attached to the latent image and developed to form a toner image. Then, the toner image on the drum is transferred onto the sheet 1 by the transfer charger 15, fixed by the fixing rollers 8 and 8 ', and then discharged onto the discharged toner. <Explanation of Smoothing Process> In the laser beam printer according to the present embodiment, as shown in FIG. 4, a pixel A to be printed (hereinafter, this pixel is referred to as a target pixel) is
The characteristics of the pixel data of the peripheral area (11 pixels in the main scanning × 9 pixels in the sub scanning) surrounding the pixel of interest are examined, and the pixel of interest is changed according to the result.

More specifically, for example, in the case of printing the target pixel A in the dot data group of the alphabetical character "a" having the resolution of 300 dpi shown in FIG. The dot data of S (11 pixels in the main scanning × 9 pixels in the sub-scanning = 99 pixels) is stored in the temporary storage means. As a result, the temporary storage means stores the dot information as shown in FIG. Then, the characteristics of the dot data group in the area S are examined, and the data of the target pixel A to be printed is changed and printed according to the characteristics. In this case, the data is changed so that the contour of the figure composed of the dot group is printed smoothly.

In the printer according to the present embodiment, a controller for a printer engine having a printing function of 600 dpi in the sub-scanning direction is used by the controller for main scanning and sub-scanning.
When transmitting image data of 00 dpi, it is equivalent to 1200 dpi in the main scanning direction in the printer engine.
i, printing is performed at a print density of 600 dpi equivalently in the sub-scanning direction.

FIG. 7 shows how to take a small image area for printing a target pixel in this embodiment. In the figure, 300 dp
The pixel of interest (5f) at the center of the dot matrix memory consisting of 11 dots in the main scanning direction of i and 9 dots in the sub scanning direction
Is a set of small image areas (x1, x2, x3, x4, y1, y2) having a print density of 4 times in the main scanning direction × 2 times in the sub scanning direction.
The image data is changed to the image data determined by y3, y4) and printed.

9 to 19 are 11 dots in the main scanning direction.
It is a figure explaining the algorithm for extracting the feature of a dot pattern over the whole area of the matrix area of 9 dots of subscanning, and checking whether it is a dot pattern which should be smoothed. 9A to 19A are diagrams showing a reference area of 11 dots in the main scanning direction × 9 dots in the sub scanning, and a, b, and a in the main scanning direction.
c, d, e, f, g, h, i, j, k, and 99 pixels in a matrix of 1, 2, 3, 4, 5, 6, 7, 8, 9 in the sub-scanning direction. Represent. For example, the central pixel is represented by 5f, and this central pixel is selected as the change target pixel for smoothing.

Further, in FIGS. 9 to 19B, the reference area of FIG. 9A is divided into 17 areas X1 to X8, Y1 to Y8 and 5f. Here, region X1 is 3d, 3e, 3f, 4d, 4e, 4f Region X2 is 3f, 3g, 3h, 4f, 4g, 4h Region X3 is 6d, 6e, 6f, 7d, 7e, 7f Region X4 6f, 6g, 6h, 7f, 7g, 7h region X5 is 3d, 3e, 4d, 4e, 5d, 5e region X6 is 5d, 5e, 6d, 6e, 7d, 7e region X8 is 5g, 5h , 6g, 6h, 7g, 7h. Further, the area Y1 includes 1a, 1b, 1c, 2a, 2b, 2c, 3
a, 3b, 3c area Y3 is 1i, 1j, 1k, 2i, 2j, 2k, 3
i, 3j, 3k area Y4 is 4i, 4j, 4k, 5i, 5j, 5k, 6
i, 6j, 6k area Y5 includes 7i, 7j, 7k, 8i, 8j, 8k, 9
i, 9j, 9k area Y7 includes 7a, 7b, 7c, 8a, 8b, 8c, 9
a, 9b, 9c area Y8 is 4a, 4b, 4c, 5a, 5b, 5c, 6
It is composed of 9 dots each of a, 6b, and 6c. Further, the region Y2 includes 1d, 1e, 1f, 1g, 1h, 2d, 2
e, 2f, 2g, 2h area Y6 is 8d, 8e, 8f, 8g, 8h, 9d, 9
e, 9f, 9g, 9h, each consisting of 10 dots. In this way, the area can be divided into eight areas (X1 to X8) of 6 dots, two areas (Y2, Y6) of 9 dots, and the central pixel 5f.

Here, the characteristics of each region will be represented as XnYn. When the dots in each area are the same for all dots (all screens are ○ <white pixels> or all pixels are ● <black pixels>), the feature (Xn, Yn) of each area is set to “0”. When the dots in each area are different from each other ((white <white pixel>, ● <black pixel> are mixed), the feature (Xn, Yn) of each area is set to “1”. For example, when all the dots in the area X1 are ◯ dots, the area X1 is “0”, and when all the dots in the area X1 are ● dots, the characteristic of the area X1 is X1 = “0”. , If the dots in the area X1 consist of ○ dots and ● dots,
The feature of the region X1 is X1 = “1”.

The characteristics of each of the above areas are detected by the circuit shown in FIG. In the figure, A1 to A16 are exclusive logic circuits, and respective areas (X1 to X8, Y1 to Y8) are obtained from the respective circuits A1 to A16. Also, FIG.
The circuit indicated by 1 is a circuit that detects that one or more of the features Yn is “0” in the regions Y1 to Y8 among the features of the above regions. That is, the characteristic signals Y1 to Y8 of the respective regions are respectively the inverter circuits B1 to B8.
After being logically inverted by, it is input to the OR circuit C1. As a result, the output Z1 of the OR circuit C1 among Y1 to Y8 is
If any one is "0", "1" is output.

FIGS. 9 to 12 show some examples of patterns to be smoothed for a graphic having a boundary line close to the vertical, using the characteristics of the respective regions. Smoothing of the boundary portion close to vertical is performed by dividing the divided small pixels with respect to the image formed by the same continuous data.
It is necessary to create change data so that at least one pixel of black data is continuously generated in the same continuous image.

An example of a pattern for smoothing will be described below with reference to the drawings. In FIG. 9, the boundary line in the vicinity of the target pixel (center pixel) 5f has a dot pattern (3f, 4f, 4e, 5e, 6e) as shown in FIG.
(White) dots and 3g, 4g, 5f, 6f
(Black) dots). In addition, the characteristic of the region is X5 = X6
When it is detected that at least one of Y1 to Y8, X7, X8, and X4 is “0”, the target pixel 5f is set to x1 = 0 (◯), x2 = 0 (◯), x3 = 1 (●), x
4 = 1 (●) y1 = 0 (○), y2 = 0 (○), y3 = 1 (●), y
Change the pixel to 4 = 1 (●) and print.

Further, in FIG. 10, the pixel of interest (center pixel)
As for the boundary line near 5f, dot patterns (3f, 4f, 5e, 6e are ● (black) dots, and 3g, 4g, 5g, 5f, 6f are ○ (white) as shown in FIG. ) Dot), the feature of the area is X7 = X8 = X4, and if it is detected that at least one of Y1 to Y8, X5, and X6 is “0”, the pixel of interest 5f is selected. x1 = 1 (●), x2 = 0 (◯), x3 = 0 (◯), x
4 = 0 (o) y1 = 1 (●), y2 = 0 (o), y3 = 0 (o), y
Change the pixel to 4 = 0 (◯) and print.

In FIG. 11, the boundary line in the vicinity of the target pixel (center pixel) 5f has a dot pattern (2f, 3e, 3f, 4e, 5e, 6e, 7e) as shown in FIG.
(White) dots and 2g, 3g, 4f, 5f, 6
f and 7f are ● (black dots), and the area feature is X5 = X6
And it is detected that at least one of Y1 to Y8, X7, and X8 is “0”, the pixel of interest 5f is set to x1 = 0 (◯), x2 = 0 (◯), x3 = 1 (●), x
4 = 1 (●) y1 = 0 (○), y2 = 1 (●), y3 = 1 (●), y
Change the pixel to 4 = 1 (●) and print.

In FIG. 12, the boundary line in the vicinity of the target pixel (center pixel) 5f has a dot pattern (2f, 3f, 4e, 5e, 6e, 7e) shown by (black) dots as shown in FIG. Then, 2g, 3g, 4g, 4f, 5f, 6f, 7f are ○.
(White dots), the feature of the region is X7 = X8, and when it is detected that at least one of Y1 to Y8, X5, and X6 is “0”, the target pixel 5f is set to x1. = 1 (●), x2 = 0 (◯), x3 = 0 (◯), x
4 = 0 (o) y1 = 0 (o), y2 = 0 (o), y3 = 0 (o), y
Change the pixel to 4 = 0 (◯) and print.

In practice, each of the patterns shown in FIGS. 9, 10, 11, and 12 has a set of feature extraction patterns in which the left and right sides of the pixel of interest (center pixel) are interchanged. For example, the left and right sides of the feature extraction shown in FIG. 9 are replaced with each other as shown in FIG. That is, 3e = 4e = 5f = 6f = 1 (●), 3f = 4f =
4g = 5g = 6g = 0 (◯), X7 = X8, and Y
If at least one of 1 to Y8, X5, X6, and X3 is “0”, the pixel of interest is x1 = 1 (●), x2 = 1 (●), x3 = 0 (◯), x
4 = 0 (◯) y1 = 1 (●), y2 = 1 (●), y3 = 0 (◯), y
Change to 4 = 0 (○). Further, a symmetrical algorithm is similarly set for FIGS. 10 to 12.

In this way, by making the feature extraction algorithm symmetrical, for example, "O""U"
Smoothing for characters such as "V" and "W" is performed by a symmetric algorithm, resulting in a natural appearance of printed characters. Further, regarding smoothing in the case where the boundary portion of the image has a horizontal boundary of 45 degrees or more with respect to the vertical, the smoothing effect can be further enhanced by using the above method.

FIGS. 14 to 17 show some examples of patterns to be smoothed for a figure having a horizontal (horizontal) boundary line by using the characteristics of the respective regions. In FIG. 14, the boundary line in the vicinity of the target pixel (center pixel) 5f is a dot pattern (5d, 5e, 4e, 4f, 4g, 4h) as shown in FIG. , 6d, 6e, 5f, 5g, 5h are ● (black)
Dot), the characteristic of the region is X5 = X2, and Y1
~ If at least one of Y8, X3, and X4 is detected to be "0", the target pixel 5f is set to x1 = 0 (○), x2 = 0 (○), x3 = 1 (●). , X
4 = 0 (○) y1 = 1 (●), y2 = 1 (●), y3 = 1 (●), y
Change the pixel to 4 = 1 (●) and print.

Further, FIG. 15 shows a target pixel (center pixel) 5
The boundary line in the vicinity of f is a dot pattern (5d, 5e, 4f, 4g, 4h as shown in FIG. 5A) (black dots) and 6d, 6e, 6f, 5f, 5g, 5h. Is ○
(White) dots), the feature of the area is X3 = X4, and if it is detected that at least one of Y1 to Y8, X1, and X2 is “0”, the target pixel 5f is selected. x1 = 1 (●), x2 = 1 (●), x3 = 0 (◯), x
4 = 1 (●) y1 = 0 (◯), y2 = 0 (◯), y3 = 0 (◯), y
Change the pixel to 4 = 0 (◯) and print.

In FIG. 16, the boundary line in the vicinity of the target pixel (center pixel) 5f has dot patterns (5c, 5d, 4d, 4e, 4f, 4g, 4h, 4i) as shown in FIG. (White) dots and 6c, 6d, 5e, 5f, 5
g, 5h, 5i are ● (black dots), the feature of the region is X1 = X2, and among Y1 to Y8, X3, and X4,
When it is detected that at least one is “0”, the target pixel 5f is set to x1 = 1 (●), x2 = 1 (●), x3 = 0 (◯), x
4 = 1 (●) y1 = 1 (●), y2 = 1 (●), y3 = 1 (●), y
Change the pixel to 4 = 1 (●) and print.

In FIG. 17, the boundary line in the vicinity of the target pixel (center pixel) 5f has dot patterns (5c, 5d, 4e, 4f, 4g, 4h, 4i) as shown in FIG.
(Black) dots and 6c, 6d, 6e, 5e, 5
f, 5g, 5h, 5i are ◯ (white) dots), the feature of the region is X3 = X4, and Y1 to Y8, X1, X2
If at least one of them is detected to be “0”, the target pixel 5f is set to x1 = 0 (◯), x2 = 0 (◯), x3 = 1 (●), x
4 = 0 (o) y1 = 0 (o), y2 = 0 (o), y3 = 0 (o), y
Change the pixel to 4 = 0 (◯) and print.

FIG. 22 is a block diagram of the VDO signal processing unit 101 which is installed in the input unit of the 600 dpi printer engine according to this embodiment and which performs the smoothing process. In the figure, SW1 to SW9 are switches, and the signals input to the line memories 1 to 9 (25 to 33) are switched by switching the respective positions of “α” and “β” in the figure. The switching positions of the switches SW1 to SW9 are controlled by a control signal SWC issued by a control circuit 47 described later.

The control circuit 47 controls the sync signal B corresponding to the sub-scanning 600 dpi for printing 600 dpi.
D'is input and BD 'is input every time the synchronization signal BD' is input.
A control signal SWC that inverts in synchronization with the signal is generated. In addition, the synchronization signal BD that interfaces with the controller
Is generated as a signal corresponding to 300 dpi in the sub-scanning, which is obtained by thinning out the synchronization signal BD 'for each line in the main scanning.

The switches SW1 to SW9 are initially set to "α".
Set to position. The controller is 300dp
The image data VDO of i is transmitted in synchronization with the BD signal.
The line memories 1 to 9 store the 300 dpi image signal VDO while sequentially shifting it in synchronization with the clock signal VCLK, and each line memory stores dot information of the main scanning length for a page to be printed. To do. That is, each line memory is line memory 1 → line memory 2 → line memory 3 → ...
The dot information of the main scanning length for 9 lines in the sub scanning direction is stored.

Thereafter, the switches SW1 to SW9 are switched to the position "β" side by the control signal SWC issued from the control circuit 47. Shift register 1
The reference numerals 9 (34 to 42) correspond to the line memories 1 to 9 and input the outputs from the line memories in synchronization with the clock signal VCKN. At this time, the line memories 1 to 9
The data output from each line memory is re-input to the switch via the switches SW1 to SW9.

Each shift register has an 11-bit configuration, and as shown in the figure, 1a to 1k, 1a to 2k, 3a to 3
k, ..., 11 dots in the main scanning direction of 9a to 9k x
A dot matrix memory of 9 lines in the sub-scanning direction is configured. Of the matrix memory, the central 5f is defined as a target dot. Further, the processing circuit 43 detects the characteristics of the data stored in the dot matrix memory and changes the pixel of interest 5f as necessary for smoothing. The processing circuit 43 includes shift registers 1 to
Each of the 9 bits (a total of 99 bits of 1a to 9k) is input, and the changed parallel signal MDT (x1, x2, x3,
x4) is output.

Parallel signal MDT (x1, x2, x3
x4) is input to the parallel-serial conversion circuit 44, and the parallel-serial conversion circuit 44 converts the input parallel signal MDT into a serial signal VDOM, and then drives the semiconductor laser 55 by the laser driver 50. After sequentially performing processing for one line of main scanning, switch SW1
~ SW9 is switched to the position "α" side. Then, in synchronization with the synchronization signal BD ′ input at the next timing, similarly, by reading from the line memories 1 to 9, the data is transferred to the next line memory and the data is output to the shift registers 1 to 9. To do.

The processing circuit 43 detects the characteristics of the data stored in the dot matrix memory of 11 dots in the main scanning direction × 9 dots in the sub scanning direction, which is output from the shift register, and detects the target pixel 5f as necessary. The parallel signal MDT (y1, y2, y3, y4) is output after being changed.
The parallel-serial conversion circuit 44 converts the input parallel signal MDT (y1, y2, y3, y4) into a serial signal VDOM, and then, the laser driver 50 shown in FIG.
The semiconductor laser 55 is driven by. And the main scan 1
Lines are processed sequentially.

Next, the switches SW1 to SW9 are switched to the position "α" side, and the image signal VDO of the next sub-scan line of 300 dpi transmitted from the control is sent.
Enter. As described above, the parallel signal in the printer according to this embodiment is 4 bits, but the synchronization signal BD '
According to the first MDT signal (x1, x2.x3, x4)
And the second MDT signals (y1, y2, y3, y4) are alternately output. The main scanning synchronization signal BD ′ signal is input from the clock generation circuit 45, and the clock signal VCK as a clock signal synchronized with this signal is generated. The clock signal VCK has a frequency twice as high as the clock frequency f0 required for recording at 600 dpi in the main scanning direction.

In synchronization with the clock signal VCK, the serial signal VDOM (x1, x2, x3, x4, or y
1, y2, y3, y4) are sequentially transmitted, and the frequency dividing circuit 46
Inputs a clock signal VCK and divides it by two to generate a clock signal VCKN having a frequency f0. The clock signal VCNK is used as a synchronous clock when the dot data is taken into the processing circuit 43 from the dot matrix memory.

23 to 26 are block diagrams showing the configuration of the feature extraction circuit in the processing circuit 43, and each circuit corresponds to the pattern example to be smoothed shown in FIGS. 9 to 12. To do. 27 to 29 show the configuration of the data generation circuit in the processing circuit 43. Figure 2
Reference numeral 7 is a data generation circuit that generates data for the target pixel 5f in accordance with the characteristics of the detected data string. In addition, FIG.
27 is a detailed circuit configuration diagram of the data generation unit 1 (61) in FIG. 27, and FIG. 29 is a detailed circuit configuration diagram of the data generation unit 2 (62).

27 to 29, Q1 to Q16 and Q1 'to Q16' are OR circuits, U1 to U6 and U3 'to.
U6 'is a 2-input AND circuit, S5-S8 are 2-input OR circuits, E4 and E18 are inverter circuits, and T1 is N.
It is an OR circuit. When generating the first MDT signal shown in FIG. 22, the control signal SW output from the control circuit 47
C becomes "1" level. In this state, 2-input AND
Circuits U3 to U6 and U3 'to U6', 2-input OR circuit S
The data from the data generator 1 is selected by 5 to S8, and x1, x2, x3, and x4 are output as parallel signals.

Further, when the second MDT signal is generated, the control signal SWC output from the control circuit 47 becomes the "0" level, and in this state, the 2-input AND circuits U3 to U6 and U3 'to U6. '2-input OR circuit S5-
The data from the data generator 2 is selected in S8, and y1, y2, y3, and y4 are output as parallel signals. Each of the output signals of the respective feature detection circuits corresponding to the plurality of patterns is O in order to select the output data of x1 to x4.
It is connected to one of the R circuits Q1 'to Q16'. Change signals (x1, x2, x3, x4, y1, y2, y in this case
3, y4) are shown in FIGS. 9 to 12 and 14 to 19.

Here, the feature detection signal detected by the algorithm of FIG. 9 is PN1 ', the feature detection signal detected by the algorithm of FIG. 12 is PN4', and the feature detection signal detected by the algorithm of FIG. 14 is PN5 '. The feature detection signal detected by the algorithm of FIG. 15 is PN6 ′, the feature detection signal detected by the algorithm of FIG. 16 is PN8 ′, and the feature detection signal detected by the algorithm of FIG. 18 is PN10 ′.

For example, when the feature of the image characterized in FIG. 9 is detected, the pixel of interest is x1 to x in FIG.
4 and the data indicated by y1 to y4 are changed and printed. In this case, x1 = 0, x2 = 0, x3 = 1, x4 = 1, that is, x
Code "C" for y1 = 0, y2 = 0, y3 = 1, y4 = 1, ie y
As in the case where the code "C" for the above is generated from the data generation circuit, the feature detection signal PN1 'output from the feature extraction circuit is input to the OR circuit Q13 and the OR circuit Q13' as shown in FIGS.

When the feature of the image characterized in FIG. 10 is detected, the pixel of interest is changed to the data shown by x1 to x4 and y1 to y4 in the figure and printed.
In this case, x1 = 1, x2 = 0, x3 = 0, x4 = 0, that is, x
Code “1” for y1 = 1, y2 = 0, y3 = 0, y4 = 0, that is, y
The feature detection signal PN2 'output from the feature extraction circuit is input to the OR circuit Q2 and the OR circuit Q2', as if the code "1" for the above is generated from the data generation circuit.

When the feature of the image characterized in FIG. 11 is detected, the pixel of interest is changed to the data shown by x1 to x4 and y1 to y4 in the figure and printed. In this case, x1 = 0, x2 = 0, x3 = 1, x4 = 1, that is, x
Code "C" for y1 = 0, y2 = 1, y3 = 1, y4 = 1, ie y
The feature detection signal PN3 'output from the feature extraction circuit is the same as the code "D" for the
Is input to the OR circuit Q14 '.

When the feature of the image characterized in FIG. 12 is detected, the pixel of interest is x1 to x in FIG.
4 and the data represented by y1 to y4 are changed and printed. In this case, x1 = 1, x2 = 0, x3 = 0, x4 = 0, that is, x
Code "1" for y1 = 0, y2 = 0, y3 = 0, y4 = 0, ie y
The feature detection signal PN4 ′ output from the feature extraction circuit is input to the OR circuit Q2 and the OR circuit Q1 ′, as if the code “0” for the data generation circuit is generated from the data generation circuit.

Similarly, for PN5 ', the code of x is "4", the code of y is "F", and OR circuit Q5 and O
It is input to the R circuit Q1 '. For PN6 ', x
Code is "B", y code is "0", and it is input to OR circuit Q7 and OR circuit Q1 '. For PN7', x code is "B", y code is "F", and OR
It is input to the circuit Q7 and the OR circuit Q8 '.

For PN8 ', the code of x is "4", y
Code becomes "0", and OR circuit Q7 and OR circuit Q
1 ', and the code of x becomes "C" and the code of y becomes "D" for PN9', and is input to the OR circuit Q13 and the OR circuit Q14 '. Then, as for PN10 ', the code of x becomes "1" and the code of y becomes "0", which are input to the OR circuit Q2 and the OR circuit Q1'.

In addition to the above feature detection circuits, the feature detection signals detected by a plurality of feature detection circuits (not shown) are also O.
One of the R circuits Q1 to Q16 and the OR circuits Q1 'to Q1
Connected to one of 6 '. Further, all the characteristic detection circuits including the characteristic detection signals PN1 'to PN10' from the characteristic detection circuit are connected to the NOR circuit T1. In this way, the code generation circuit 200 'outputs the dot code corresponding to each output of the OR circuits Q1 to Q16 and Q1' to Q16 '. This code generation circuit 200 'is
Codes of "0" to "F" are generated as 4-bit codes of 20, 21, 22, 23 as a code for x output and a code for y output.

The 20 digits of these code outputs are ORed by the OR circuit S5 and output as the output x1 or the output y1. Further, the 21 digit of the code output is ORed by the OR circuit S6, and the 22 digit of the code output is ORed by the OR circuit S7 as the output x2 or the output y2, and the output x3 or the output y3. Furthermore, the 23 digit of the code output is logically ORed by the OR circuit S8,
It is output as the output x4 or the output y4, respectively.

In this way, one code "0" to "F" corresponding to the outputs of Q1 to Q16 which are not selected at the same time is output as the outputs X1 to X4. Also, no more than one Q1 'is selected at the same time.
~ One code "0" corresponding to the output of Q16 '~
“F” is output as the outputs y1 to y4. For example,
When the code of x is “3”, x = 1, x2 = 1, x
3 = 0, x4 = 0, and when the code of Y is "F", y1 = 1, y2 = 1, y3 = 1, y4 = 1.

Since all the feature detection signals are connected to the input of the NOR circuit T1, if none of the feature detection signals becomes "1", that is, if no features match. Causes the output of T1 to be "1". At this time, when the target pixel 5f is a dot, the output of the 2-input AND circuit U1 becomes "1", the outputs of the OR circuits Q1 and Q1 'are set to "1", and the codes x1 to x4 and y1 to y4 are coded. Output "0" (x1 = 0, x2 = 0, x3 = 0, x4
= 0, and y1 = 0, y2 = 0, y3 = 0, y4 =
0)

If the target pixel 5f is a dot, 2
The output of the input AND circuit U2 becomes "1", and the OR circuit Q
16 and Q16 'are set to "1", and codes "F" are output to x1 to x4 and y1 to y4 (x1 = 1, x2 =
1, x3 = 1, x4 = 1, and y1 = 1, y2 = 1, y
3 = 1, y4 = 1). In this way, when the feature does not match the predetermined feature, the data of the target pixel 5f is stored as it is and printed.

The outputs x1 to x4 of the data generating circuit are
By the parallel-serial conversion circuit 44, x1, x2, x
A signal VDOM that is output in synchronization with the clock signal VCK is generated in the order of 3 and 4. Similarly, the outputs y1 to y4 of the data generation circuit generate a signal VDOM output by the parallel-serial conversion circuit 44 in the order of y1, y2, y3, y4 in synchronization with the clock signal VCK. The signal drives the semiconductor laser.

As a result, for example, the one-dot line near vertical in FIG. 30 (a) is converted into a signal as shown in FIG. 30 (b), and the smoothing effect of the shaded portion is produced.
Further, for example, the one-dot line near horizontal in FIG. 31A is converted into an independent signal in the main scanning direction of 1200 dpi as shown in FIG. 31B, and the effect of smoothing the shaded portion is produced.

The image of FIG. 32 (A), which is a part of the alphabetic character "a" shown in FIG.
As shown in FIG. 32 (B), a semiconductor laser is driven and printed as an image in which 1200 dpi independent dots are provided in a part of the outline of a character in the main scanning direction. The independent dots bring about an effect of changing the image density at the local portion of the contour portion by the electrophotographic process, or an effect of shifting the print position of the print dot. by this,
The outline portion of the character is printed as a smoothed image on the paper surface.

As described above, according to this embodiment,
The feature of the dot pattern in the peripheral area of the pixel of interest is extracted for the entire predetermined region, and the dot pattern of the boundary of the figure to which the pixel of interest belongs is determined by a plurality of predetermined features and the dot pattern of the boundary. By collating with the combined collation pattern and changing the pixel of interest when both patterns match, a simplified logic circuit can be used to refer to a wide reference area to identify contours near horizontal or near vertical. It is possible to detect and perform the optimum smoothing correction according to the curvature of the contour of the character or figure.

In the above embodiment, a function of identifying a binarized halftone image such as a dither image or that graphics are dense is added to prohibit smoothing processing for the dither image or the dense image. This makes it possible to improve the deterioration of the halftone image. In addition, by performing the pixel change for smoothing only when there is a predetermined white area around the target pixel to be changed, the smoothing effect is less affected by the environment. It will be.

In the first embodiment, for the printer engine having a printing function of 600 dpi in the sub-scanning direction, the controller scans 30 main scans and 30 sub-scans.
When image data of 0 dpi is transmitted, the resolution is equivalent to 4 times the resolution in the sub-scanning direction (1200 dpi) in the printer engine and 6 in the sub-scanning direction.
The case of printing with the printing density of 00 dpi has been described.

However, the equivalent print density in the main scanning direction need not be limited to 4 times that in the sub scanning direction, but may be 2 times, 3 times, 4 times,
It may be 5 times, 6 times, 7 times, 8 times, ...
For example, the resolution of 8 in the sub-scanning direction is equivalent to that in the main scanning direction.
When the smoothing processing is performed at double (2400 dpi), the pattern generation unit of the change pattern generation circuit is set to 4 times.
Not small bit signals (x1 to x4, y1 to y4)
One pixel may be configured with 8-bit small signals (x1 to x8, y1 to y8). [Second Embodiment] A second embodiment according to the present invention will be described below.

In this embodiment, similar to the first embodiment,
As shown in FIG. 4, with respect to the pixel A to be printed (this pixel is referred to as a target pixel), the characteristics of the pixel data in the peripheral region (main scanning 11 pixels × sub scanning 9 pixels) surrounding the target pixel are examined. Then, the target pixel is changed according to the result. Further, in the present embodiment, 600 dpi in the sub-scanning direction
The image data of 300 dpi is transmitted from the controller to the printer engine having the printing function in both main scanning and sub-scanning, and within the printer engine, it is equivalent to 1200 dpi in the main scanning direction and in the sub-scanning direction. An equivalent case of printing at a print density of 600 dpi will be described. The configuration of the VDO signal processing unit for smoothing processing according to the present embodiment is the same as that of the first embodiment shown in FIG.
Since it has the same configuration as the VDO signal processing unit according to the embodiment, the description thereof will be omitted here.

As in the first embodiment, as shown in FIG. 7, the method of obtaining the small image area for printing the pixel of interest in this embodiment is from 300 dots in the main scanning direction to 11 dots in the main scanning direction × 9 dots in the sub scanning direction. The pixel of interest (5f) in the central portion of the dot matrix memory
4, y1, y2, y3, y4) and change the pixel data to print.

Here, according to FIGS. 33 to 36, from the matrix area of 11 dots in the main scanning direction × 9 dots in the sub scanning direction, the characteristics of the dot pattern are extracted over the entire area of the matrix area, and the dots to be smoothed. Check if it is a pattern. And these FIG. 33-
FIG. 36 shows some examples of patterns to be smoothed for a figure having a boundary line which is almost horizontal in this embodiment.

In FIG. 33, the boundary line in the vicinity of the pixel of interest (center pixel) 5f is a dot pattern (5d, 5e, 4e, 4f, 4g, 4h) as shown in FIG. And 6d, 6e, 5f, 5g, 5h are ● (black)
(Dots), the feature of the area is X5 = X7, and Y1 to Y
When at least one of 8, X3 and X4 is detected to be “0”, the target pixel 5f is set to x1 = 0 (◯), x2 = 0 (◯), x3 = 0 (◯), x
4 = 1 (●) y1 = 1 (●), y2 = 1 (●), y3 = 1 (●), y
Change the pixel to 4 = 0 (◯) and print.

Further, FIG. 34 shows the target pixel (center pixel) 5
The boundary line in the vicinity of f is a dot pattern (5d, 5e, 4f, 4g, 4h as shown in FIG. 5A) (black dots) and 6d, 6e, 6f, 5f, 5g, 5h. Is ○
(White) dots), the feature of the region is X3 = X4, and at least one of Y1 to Y8, X1, and X2
If it is detected that one is “0”, the pixel of interest 5
f is x1 = 1 (●), x2 = 1 (●), x3 = 0 (◯), x
4 = 1 (●) y1 = 0 (◯), y2 = 0 (◯), y3 = 0 (◯), y
Change the pixel to 4 = 0 (◯) and print.

In FIG. 35, the boundary line in the vicinity of the pixel of interest (center pixel) 5f has a dot pattern (5c, 5d, 4d, 4e, 4f, 4g, 4h, 4i) as shown in FIG. (White) dots and 6c, 6d, 5e, 5f, 5
g, 5h, 5i are ● (black dots), the feature of the region is X1 = X2, and among Y1 to Y8, X3, and X4,
When it is detected that at least one is “0”, the target pixel 5f is set as x1 = 0 (◯), x2 = 1 (●), x3 = 0 (◯), x
4 = 1 (●) y1 = 1 (●), y2 = 0 (◯), y3 = 1 (●), y
Change the pixel to 4 = 1 (●) and print.

In FIG. 36, the boundary line in the vicinity of the target pixel (center pixel) 5f has dot patterns (5c, 5d, 4e, 4f, 4g, 4h, 4i) as shown in FIG.
(Black) dots and 6c, 6d, 6e, 5e, 5
f, 5g, 5h, 5i are ◯ (white) dots), the feature of the region is X3 = X4, and Y1 to Y8, X1, X2
If at least one of them is detected to be “0”, the target pixel 5f is set to x1 = 0 (◯), x2 = 1 (●), x3 = 0 (◯), x
4 = 0 (o) y1 = 0 (o), y2 = 0 (o), y3 = 0 (o), y
Change the pixel to 4 = 0 (◯) and print.

FIG. 37 is a diagram showing the effect of smoothing in the present embodiment. One dot line which is almost horizontal in FIG. 37A is independent in the main scanning direction of 1200 dpi as shown in FIG. It can be seen that it is converted into a different signal and produces the effect of smoothing in the shaded area. 38, which is a part of the alphabetic character "a" shown in FIG.
The image of (A) is, for example, as shown in (B) of the figure, an image in which independent dots of 1200 dpi in the main scanning direction and 600 dpi in the sub-scanning direction are provided in a part of the outline of a character as a semiconductor laser. Drive and be printed. The independent dots have the effect of changing the local image density of the contour portion by the electrophotographic process.

As described above, this embodiment also has an effect that the contour portion of the character is printed as a smoothed image on the paper surface. [Third Embodiment] Next, a third embodiment of the present invention will be described. In the third embodiment, as in the first embodiment, as shown in FIG. 4, with respect to the pixel A (target pixel) to be printed, the peripheral area surrounding the target pixel (main scanning 11 pixels × Check the characteristics of the pixel data of 9 pixels in the sub-scan,
The target pixel is changed according to the result.

Further, in the present embodiment, as in the first embodiment, a controller having a printer engine having a printing function of 600 dpi in the sub-scanning direction is used to output image data of 300 dpi from the controller in both main scanning and sub-scanning. Is transmitted in the printer engine, the print density is equivalent to 1200 dpi in the main scanning direction and the print density is equivalent to 600 dpi in the sub scanning direction.

Also in this embodiment, as in the case of the first embodiment, a method of obtaining a small image area for printing a target pixel as shown in FIG. 7 is performed. Further, in the same figure, the pixel of interest (5f) at the center of the dot matrix memory consisting of 11 dots in the main scanning direction and 9 dots in the sub scanning direction of 300 dpi is printed 4 times in the main scanning direction and 2 times in the sub scanning direction. A set of small fractions of density (x1, x2, x3, x4, y1, y2, y3,
The image data is changed to the image data determined by y4) and printed. Then, according to FIGS. 39 to 42, the main scanning direction 11
The characteristics of the dot pattern are extracted from the matrix area of dots × 9 dots in the sub-scanning over the entire area of the matrix area, and it is checked whether or not this is a dot pattern to be smoothed.

39 to 42 show examples of some patterns to be smoothed for a figure having a boundary line near horizontal in the present embodiment. As can be seen from the figure, in the algorithm according to the present embodiment, the light amount of the dot in the diagonal line portion for which the smoothing process is performed is reduced from the standard light amount, for example, 50% light amount is added to the standard light amount, and three levels are obtained. To print.

FIG. 43 shows 600 dpi according to this embodiment.
FIG. 23 is a circuit block diagram of a VDO signal processing unit installed in an input unit of the printer engine of FIG. 1 for performing smoothing. Here, the VDO signal processing unit shown in FIG.
The same components as those of the DO signal processing section are designated by the same reference numerals. In FIG. 43, when the image signal VDO of 300 dpi is transmitted from the controller to the printer in synchronization with the image clock signal VCLK, the image dot data is sequentially stored in the line memories 1 to 9 (25 to 33). To be done. At the same time, shift registers 1-9 (34-42)
In the dot data of the line memories 1 to 9, main scanning 1
The dot matrix information of 1 dot × 9 dots in the sub-scan is taken out.

Then, the processing circuit 43 detects the characteristics of the dot matrix information, and according to the detected characteristics, divides the target pixel into four equal parts in the main scanning direction and two equal parts in the sub scanning direction. 8 data (parallel signal MDT: X1
To X4, or Y1 to Y4) and a code (parallel signal LDT: LX1) that indicates the irradiation intensity of each dot.
˜LX4, or LY1 to LY4).

The feature extraction circuit section constituting the processing circuit 43 is the same as the circuit according to the first embodiment shown in FIGS. 20, 21, and 23 to 26. FIG. 44 is a block diagram showing the internal configuration of the processing circuit 43. First above
The control signal S output from the control circuit 47 (FIG. 43) when the first MDT signal described in the embodiment of FIG.
WC is at "1" level. In this state, the data generator 1 is selected, and the parallel signals x1 and x are transmitted via the 2-input OR circuits S5 to S8 and the 2-input OR circuits S9 to S12.
2, x3, x4, and lx1, lx2, lx3, lx4
Is output.

Further, when the second MDT signal is generated, the control signal SWC output from the control circuit 47 is at "0" level. In this state, the data generator 2 is selected by the 2-input AND circuits U3 ′ to U10 ′.
Parallel signals y1, through the input OR circuits S5 to S12
y2, y3, y4, and ly1, ly2, ly3, ly
4 is output.

Similar to the first embodiment, the parallel signal MDT is input to the parallel-serial conversion circuit 44 by alternating x1 to x4 and y1 to y4 and converted into the serial signal VDOM in synchronization with the clock VCK. The serial signal VDOM is sent to the laser driver 50 to drive the semiconductor laser 55. In this embodiment, the parallel signal LD
Also in T, lx1 to lx4 and ly1 to ly4 are alternately input to the parallel-serial conversion circuit 48, and the serial signal VDOL (lx1, lx2, lx is synchronized with the clock VCK.
3, lx4 or ly1, ly2, ly3, ly
It is converted into 4) and input to the laser driver.

FIG. 45 is a circuit block diagram of the laser driver 50 according to this embodiment. As shown in the figure, the laser driver unit includes two constant current circuits LD1 and LD2.
In the present embodiment, the current setting corresponding to the light amount of 50% with respect to the standard light amount is made.
Of the two constant current circuits, the AND circuit of FIG.
LD1 is switched on / off only by the serial signal VDOM regardless of the serial signal VDOL. In addition, the LD2 is connected to the serial signals VDOM and VDOL.
ON / OFF is switched by taking the logical product of. Since the combined currents from these two constant current circuits are configured to flow to the laser diode LD, the parallel signals MDT and LDT cause the light amount of each dot to have three levels (here, no light is emitted). , 50% light intensity, standard light intensity).

That is, LX1 sets the light quantity of the dot designated by X1, and similarly, LX2 corresponds to X2, ..., LY1 corresponds to Y1, ..., LY4 corresponds to Y4, and when LX1 = 1, the standard light quantity, When LX1 = 0, the light amount is 50%. Therefore, the feature extraction of the dot patterns shown in FIGS. 39 to 42 will be individually described.

In FIG. 39, the boundary line in the vicinity of the pixel of interest (center pixel) 5f is a dot pattern (5d, 5e, 4e, 4f, 4g, 4h) as shown in FIG. And 6d, 6e, 5f, 5g, 5h are ● (black)
Dot), and the feature of the area is X5 = X2 and Y1
-When at least one of Y8, X3, and X4 is detected to be "0", the target pixel 5f is set to x1 = 0 (○), x2 = 0 (○), x3 = 0, lx3 = 0 (⊚), x4 = 1, lx4 = 0
(⊚) y1 = 1, ly1 = 1 (●), y2 = 1, ly2 = 1
(●) y3 = 1, ly3 = 1 (●), y4 = 0, ly4 = 1
Change to the pixel marked with (●) and print. In addition, here, the dot by the laser current of irradiation light amount lower than the standard light amount,
Represented by the symbol (◎).

Further, FIG. 40 shows the target pixel (center pixel) 5
The boundary line in the vicinity of f is a dot pattern (5d, 5e, 4f, 4g, 4h as shown in FIG. 5A) (black dots) and 6d, 6e, 6f, 5f, 5g, 5h. Is ○
(White) dots), the feature of the area is X3 = X4, and Y
When it is detected that at least one of 1 to Y8, X1, and X2 is “0”, the target pixel 5f is set to x1 = 1, lx1 = 1 (●), x2 = 1, lx2 = 1.
(●) x3 = 0, lx3 = 0 (⊚), x4 = 1, lx4 = 1
(●) y1 = 0 (◯), y2 = 0 (◯), y3 = 0 (◯), y
Change the pixel to 4 = 0 (◯) and print.

In FIG. 41, the boundary line in the vicinity of the target pixel (center pixel) 5f has a dot pattern (5c, 5d, 4d, 4e, 4f, 4g, 4h, 4i) as shown in FIG. (White) dots and 6c, 6d, 5e, 5f, 5
g, 5h, 5i are ● (black dots), and the feature of the region is X1 = X2, and among Y1 to Y8, X3, and X4,
When it is detected that at least one is “0”, the target pixel 5f is set to x1 = 0, lx1 = 1 (●), x2 = 0, lx2 = 0
(⊚) x3 = 0, lx3 = 0 (⊚), x4 = 1, lx4 = 1
(●) y1 = 1, ly1 = 1 (●), y2 = 1, ly2 = 1
(●) y3 = 1, ly3 = 1 (●), y4 = 1, ly4 = 1
Change to the pixel marked with (●) and print.

In FIG. 42, the boundary line in the vicinity of the target pixel (center pixel) 5f has dot patterns (5c, 5d, 4e, 4f, 4g, 4h, 4i) as shown in FIG.
(Black) dots and 6c, 6d, 6e, 5e, 5
f, 5g, 5h, 5i are ◯ (white) dots), the feature of the region is X3 = X4, and Y1 to Y8, X1, X2
When at least one of the pixels is detected to be “0”, the pixel of interest 5f is set to x1 = 1, lx1 = 0 (⊚), x2 = 1 (∘) x3 = 0 (∘), x4 = 1 (o) y1 = 0 (o), y2 = 0 (o), y3 = 0 (o), y
Change the pixel to 4 = 0 (◯) and print.

As a result, for example, one dot line which is almost horizontal in FIG. 46 (a) has 12 dots as shown in FIG. 46 (b).
The smoothing effect of the shaded portion changed to an independent signal in the main scanning direction of 00 dpi is produced. 47 is a part of the alphabetic character "a" shown in FIG.
In the image of (A), for example, as shown in (B) of the figure, independent dots of 1200 dpi in the main scanning direction and 600 dpi in the sub scanning direction are provided in a part of the outline portion of the character, and the amount of weak light is interposed between them. An image with dots is printed by driving a semiconductor laser.

The combination of the independent dots and the weak light intensity dots brings about an effect of changing the image density at the local portion of the contour portion by the electrophotographic process or an effect of shifting the print position of the print dots. In this way, in addition to the standard light intensity, the light intensity obtained by reducing the light intensity of the dots from the standard light intensity causes the outline portion of the character to be printed as a smoothed image on the paper surface.

The present invention may be applied to a system composed of a plurality of devices or 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.

[0115]

As described above, according to the present invention,
Optimum smoothing correction can be performed by changing the pixel of interest according to the characteristics of the dot pattern in a predetermined area.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an engine unit of a laser beam printer according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an engine unit of a laser beam printer according to an embodiment of the present invention.

FIG. 3 is a diagram showing an interface signal between a printer engine unit and a controller.

FIG. 4 is a diagram showing a pixel of interest for printing.

FIG. 5 is a diagram illustrating a pixel of interest and surrounding pixels according to an example.

FIG. 6 is a diagram showing dot data including a pixel of interest stored in a primary storage unit.

FIG. 7 is a diagram showing a method of obtaining a small image area for printing a target pixel according to the embodiment.

FIG. 8 is a diagram showing an example of a pattern represented by dot data.

FIG. 9 is a diagram showing an algorithm of feature extraction of a dot pattern according to the first embodiment.

FIG. 10 is a diagram showing an algorithm of dot pattern feature extraction according to the first embodiment.

FIG. 11 is a diagram showing an algorithm of dot pattern feature extraction according to the first embodiment.

FIG. 12 is a diagram showing an algorithm of dot pattern feature extraction according to the first embodiment.

FIG. 13 is a diagram showing an algorithm of feature extraction of a dot pattern according to the first embodiment.

FIG. 14 is a diagram showing an algorithm of dot pattern feature extraction according to the first embodiment.

FIG. 15 is a diagram showing an algorithm of feature extraction of a dot pattern according to the first embodiment.

FIG. 16 is a diagram showing an algorithm of dot pattern feature extraction according to the first embodiment.

FIG. 17 is a diagram showing an algorithm of dot pattern feature extraction according to the first embodiment.

FIG. 18 is a diagram showing an algorithm of dot pattern feature extraction according to the first embodiment.

FIG. 19 is a diagram showing an algorithm of dot pattern feature extraction according to the first embodiment.

FIG. 20 is a diagram showing a feature detection circuit of each area obtained by dividing a reference area.

FIG. 21 is a diagram showing a feature detection circuit for regions Y1 to Y8.

FIG. 22 is a diagram showing a circuit configuration of a VDO signal processing unit according to the first example.

FIG. 23 is a diagram showing the configuration of a feature extraction circuit in the processing circuit according to the first example.

FIG. 24 is a diagram showing the configuration of a feature extraction circuit in the processing circuit according to the first example.

FIG. 25 is a diagram showing a configuration of a feature extraction circuit in the processing circuit according to the first example.

FIG. 26 is a diagram showing the configuration of a feature extraction circuit in the processing circuit according to the first example.

FIG. 27 is a diagram showing a configuration of a data generation circuit that generates data of a target pixel.

FIG. 28 is a diagram showing a detailed circuit configuration of the data generator 1.

FIG. 29 is a diagram showing a detailed circuit configuration of the data generator 2.

FIG. 30 is a diagram showing an effect of smoothing a shaded portion according to the first embodiment.

FIG. 31 is a diagram showing an effect of smoothing a hatched portion according to the first example.

32 is a diagram showing an example in which a part of the contour portion is smoothed to the character shown in FIG.

FIG. 33 is a diagram showing an algorithm of feature extraction of a dot pattern according to the second embodiment.

FIG. 34 is a diagram showing an algorithm of dot pattern feature extraction according to the second embodiment.

FIG. 35 is a diagram showing an algorithm of dot pattern feature extraction according to the second embodiment.

FIG. 36 is a diagram showing an algorithm of dot pattern feature extraction according to the second embodiment.

FIG. 37 is a diagram showing an effect of smoothing according to the second embodiment.

38 is a diagram showing an example in which a part of the contour portion is smoothed to the character shown in FIG.

FIG. 39 is a diagram showing an algorithm for feature extraction of a dot pattern according to the third embodiment.

FIG. 40 is a diagram showing an algorithm of dot pattern feature extraction according to the third embodiment.

FIG. 41 is a diagram showing an algorithm of dot pattern feature extraction according to the third embodiment.

FIG. 42 is a diagram showing an algorithm of feature extraction of a dot pattern according to the third embodiment.

FIG. 43 is a diagram showing a circuit configuration of a VDO signal processing unit according to the third embodiment.

FIG. 44 is a diagram showing an internal configuration of a processing circuit according to the third embodiment.

FIG. 45 is a diagram showing a configuration of a laser driver circuit according to a third example.

FIG. 46 is a diagram showing an effect of smoothing according to the third embodiment.

47 is a diagram showing an example in which a part of the contour portion is smoothed to the character shown in FIG.

FIG. 48 is a diagram showing a state of a dense line group by extracting a part of a dither image.

[Explanation of symbols]

 25-33 Line memory 1-934-42 Shift register 1-943 Processing circuit 44,48 Parallel-serial conversion circuit 47 Control circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H04N 1/23 103 Z 9186-5C 1/40 101 C 9068-5C // G09G 5/28 8121- 5G

Claims (7)

[Claims] 1. An information recording apparatus for forming an electrostatic latent image on a recording medium with a light beam modulated according to an information signal, and visualizing the electrostatic latent image to record information. Means for storing a dot data group consisting of a plurality of bit information obtained, means for extracting the characteristics of the dot pattern in the peripheral region of the pixel of interest, and when the dot data in the dot data group and the dot pattern match An information recording apparatus comprising: a pixel information changing unit that changes the print information corresponding to the target pixel based on the dot data. 2. The pixel information changing unit arranges print dots independent of the main scanning direction in an area obtained by dividing the pixel of interest in the main scanning direction and the sub-scanning direction. The information recording device according to item 1. 3. The pixel of interest changed by the pixel information changing means is composed of a section having a double resolution in the sub-scanning direction and a 4-fold or 8-fold resolution in the main scanning direction. The information recording device according to item 2. 4. The pixel information changing unit arranges print areas, which are independent of each other in the main scanning direction and the sub scanning direction, in an area obtained by dividing the target pixel in the main scanning direction and the sub scanning direction. The information recording device according to claim 1. 5. The pixel of interest changed by the pixel information changing means is composed of a section having a double resolution in the sub-scanning direction and a four-fold or eight-fold resolution in the main-scanning direction. The information recording device according to item 4. 6. The pixel information changing unit arranges an independent dot in the main scanning direction in an area obtained by dividing the pixel of interest in the main scanning direction and the sub-scanning direction, and surrounds the dot. The information recording apparatus according to claim 1, wherein dots are formed by a light beam having a light intensity weaker than that of the dots. 7. The pixel of interest changed by the pixel information changing means is composed of a section having a double resolution in the sub-scanning direction and a four-fold or eight-fold resolution in the main-scanning direction. Item 6. The information recording device according to item 6.