JP2001232858A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breaking of edge sections of a black vertical line in a width of one dot, a vertical line in a width of one dot in an intermediate density and a vertical line in a width of plural dots in a multi-value image. SOLUTION: A pattern detecting section 50 detects whether or not a line is a vertical line in a width of one dot based on a target pixel and a pattern of two-bit data of a peripheral pixel adjacent thereto in a main scanning direction and a data converting section 60 converts multi-value data of the pixel forming the vertical line to light emission data so as to enlarge the width of the vertical line. The pattern detecting section 50 detects whether or not the portion is the edge of the vertical line in a width of plural dots based on the target pixel and the pattern of two-bit data of a peripheral pixel adjacent thereto in the main scanning direction and the data converting section 60 coverts multi-value data of the pixel forming the edge to light emission data so as to allow the edge to be continuous with the vertical line.

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 capable of thickening black vertical lines of one dot width, vertical lines of one dot width of intermediate density, and edges of vertical lines of plural dot widths. .

[0002]

2. Description of the Related Art (1) In an image thickening processing method disclosed in Japanese Patent Laid-Open No. Hei 10-313410, as shown in FIG. 14, regions A, B, CD, E, and F of 3 × 3 pixels of an image are used. In G, H, I, peripheral pixels A to D separated from the lower right pixel I by two pixels,
Looking at the relationship of G, when I is a black pixel, if C is white, F is a black pixel, if G is white, H is a black pixel, and A,
If B and D are white, a method has been proposed in which E is set as a black pixel to make a thick line to prevent the loss of white and to make a thick line in units of one pixel width.

(2) Japanese Patent Application Laid-Open No. Hei 9-300698 discloses that the printing position of both sides of a pixel of interest is changed within one clock to make the line thicker (or thinner), thereby making the line thicker. In such a case, a method has been proposed in which the printing positions of the pixels on both sides are widened outward to make the line thicker in units of a width within one pixel.

As another conventional example, (3) Japanese Patent Application Laid-Open No. HEI 9-295429 discloses a single pixel width of black and white and black and white in order to clearly reproduce an isolated one pixel point and a line of one pixel width. In order to clearly reproduce the pair of lines, a method of increasing or decreasing the pulse width of the recording signal of the black pixel has been proposed. Also, (4) Japanese Patent Application Laid-Open No. 5-20454 discloses that in order to generate a bold and thick bold character,
There has been proposed a method of binarizing a character image, separating the character image into a character portion and a background portion, and thinning the background portion. Also, (5) Japanese Patent Application Laid-Open No. 10-276329 discloses a technique for smoothing an image.

There has been proposed a method of recognizing a white pixel area, a gray pixel area and a black pixel area to determine an image density. Also, (6) JP-A-5-219359 discloses that
There has been proposed a method of once widening and reducing a thin line so that the thin line does not disappear when the image is reduced. Also, (7) Japanese Patent Application Laid-Open No. Hei 9-300698 discloses that in order to make a multicolor image thicker and thinner, the lighting position of the laser diode is set to a width within both end pixel sections in the width direction of the linear image area. A method has been proposed that allows the direction to be changed back and forth.

[0006]

However, (1)
In the invention described in Japanese Patent Application Laid-Open No. H10-313410, thick lines can be formed only for binary image data, but multi-valued images cannot be thickened. Because how to increase is dot unit,
There is a problem in that if the text is prevented from being blurred, etc., and it is easy to read, the character becomes too fat. Also, (2) JP-A-9-3
In the invention described in Japanese Patent Application Publication No. 00698, there is a problem that a vertical line having a dot width of 1 dot width of intermediate density cannot be thickened because only the printing positions of the pixel data on both sides are moved.

Here, for example, the character "I" as shown in FIG. 13A is composed of a relatively long vertical stroke and relatively short horizontal strokes attached to the upper and lower ends of the vertical stroke. Is done. Then, as shown in FIG. 13A, the horizontal width of the vertical stroke is less than 1 dot,
When the horizontal width of the horizontal stroke extends over two dots in the horizontal direction, if one dot is converted into two bits, each dot data of the vertical stroke becomes "01" as shown in FIG. 2 dots is "01",
It becomes "11".

For this reason, if this 2-bit data is converted into light emission data as it is and printed, the vertical stroke (= 01) is blurred as shown in FIG. The dot on the left side of the stroke (= 01) is separated from the dot on the right side (= 11), and the horizontal stroke is interrupted, thus deteriorating the image quality. Also,
Although not shown in the drawing, for example, when a vertical stroke having a horizontal width of less than 1 dot extends over two horizontal dots, if the image is fixed and printed left-aligned, two vertical strokes are generated and the image quality deteriorates. Becomes

In view of the above-mentioned problems of the prior art, the present invention provides a multi-valued image in which a black vertical line of 1 dot width, a vertical line of 1 dot width of intermediate density, and an edge portion of a vertical line of plural dot widths are formed. An object of the present invention is to provide an image forming apparatus capable of preventing interruption.

According to the present invention, even when the phase data for controlling the light emission timing does not include multi-valued data, the edge of a line extending over a plurality of pixels or a single black dot line is thickened to further reduce white. It is an object of the present invention to prevent blurring of characters and obtain an image with good visibility.

Another object of the present invention is to simplify the hardware configuration by reducing the number of patterns to be detected, and to prevent the occurrence of an abnormal image due to unnecessary correction.

Another object of the present invention is to make it possible to cope with a case where the printer uses a negative / positive developing system.

Another object of the present invention is to enable the printer to be compatible with a positive / positive developing system.

[0014]

In order to achieve the above object, a first means is an image forming apparatus for forming an image based on input image information, the image forming apparatus being adjacent to a target pixel in the main scanning direction. Pattern detecting means for detecting whether or not the vertical line has a width of one dot based on the pattern of each multi-valued data of the peripheral pixels; and forming the vertical line so that the width of the vertical line detected by the pattern detecting means becomes large. Data conversion means for converting the multi-value data of the constituent pixels into print data.

A second means is the first means, wherein the pattern detecting means further comprises a vertical line having a plurality of dot widths based on a pattern of each multivalued data of the target pixel and its neighboring pixels in the main scanning direction. The data conversion means further changes the multi-valued data of the pixels constituting the edge into emission data so that the edge is continuous with the vertical line.

The third means is the first or the second means, wherein the pattern detecting means is configured such that the left and right pixels of the target pixel are white or black and the one dot is set when the target pixel is halftone or white. It is characterized by determining the edge of a vertical line having a width or a vertical line having a plurality of dot widths.

A fourth means is the second or third means, wherein the pattern detecting means adjusts the phase data for shifting the multi-value data of the pixels constituting the edge of the vertical line having a plurality of dot widths. Is generated.

The fifth means is characterized in that, in the first to fourth means, when the data conversion means outputs to a negative / positive development type printer, the data is converted so that the light emission amount increases.

The sixth means is characterized in that, in the first to fifth means, when the data conversion means outputs the data to a printer of the positive / positive developing system, the data is converted so that the light emission amount is reduced.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an external view showing a digital copying machine as an embodiment of an image forming apparatus according to the present invention, and FIG.
FIG. 3 is a block diagram showing an image processing circuit of the digital copying machine of FIG.
3 is a timing chart showing main signals in the data delay unit in FIG. 3, FIG. 5 is an explanatory diagram showing an image control signal, and FIG. 6 is an explanatory diagram showing a relationship between 2-bit density data and printing dots and a relationship between phase data and printing positions. 7, FIG. 7 is an explanatory diagram showing a matching pattern detected by the pattern detection unit of FIG. 2, FIGS. 8 to 10 are block diagrams showing the pattern detection unit of FIG. 2 in detail, and FIG. FIG. 12 is a block diagram illustrating the data conversion unit in FIG. 2 in detail, and FIG. 13 is an explanatory diagram illustrating thickening and width adjustment processing of the image processing circuit in FIG.

At the top of the digital copying machine 1 shown in FIG.
An original platen 2 for placing and reading an original, a pressure plate 3 for holding down the original on the original platen 2, and an operation unit 4 for setting a mode for reading, a copy magnification, and displaying to an operator are provided. ing. Further, a paper feed unit 5 is provided on the lower side, and a paper discharge unit 6 is provided on the left side. Digital copier 1
Although not shown in the figure, known mechanisms and controls of a digital copying machine such as an exposure optical system, a paper feeding and conveying system, a developing system, a fixing system, and a paper discharging system are used to realize the operation as a copying machine. The device is built-in.

In such a configuration, the original is placed on the original platen 2
After the original is brought into close contact with the pressure plate 3, the original is read by an illumination system and an imaging optical system (not shown) according to an instruction from the operation unit 4. After performing various corrections on the read image data, a laser diode (hereinafter referred to as L) is used in a writing system based on the image data.
D) irradiates a beam to form an electrostatic latent image on a photosensitive member (not shown). Thereafter, through a known electrophotographic process, a copy image is formed on a sheet fed from the sheet feeding unit 5 instructed by the operation unit 4.

FIG. 2 shows an image processing circuit of the digital copying machine 1. First, in the reading processing unit 10, a CC (not shown)
The image data read at, for example, 600 dpi by the D line sensor is subjected to various corrections such as shading correction, and the image data Da is 8 bits per pixel (256 bits).
(Gradation) to the image processing unit 20. The image processing unit 20 performs image quality correction by performing MTF correction, scaling processing, and the like on the image data Da, converts the image data Da into 2-bit (four gradation) image data Db, and outputs the image data Db to the writing processing unit 30. I do.

In the writing processor 30, first, the image data Db is delayed in the main scanning direction by flip-flops (F / F) 41 to 43 as shown in detail in FIGS. 3 pixels Dc in main scanning direction
A data array of 1 to Dc3 is created, and this image data Dc1
ＤDc3 (2 bits × 3) are output to the pattern detection unit 50. The pattern detection unit 50 detects whether or not each of the patterns coincides with a specific 10 patterns (described later) such as an edge portion of an image and a 1-dot line, and outputs the detection results Dd1 to Dd8 (8 bits) for each pattern. The data is output to the data converter 60.

The detection results Dd1 to Dd8 are composed of data indicating whether or not they match for each specific pattern, or data indicating the density value of the pixel of interest if they do not match. Further, the pattern detection unit 50 also generates 1-bit phase data Ds indicating whether the writing position is performed from the right or from the left.

The detection results Dd1 to Dd8 are transmitted to the data converter 6
0, the 8-bit light emission data D according to the detection result.
e. The 8-bit light emission data D
e and the phase data Ds generated by the pattern detection unit 50
The writing density and the writing start position for the edge portion and the one dot line portion in the image data are changed by modulating the light emission time and / or the light emission power of the LD based on the above. Write to the photoconductor.

The control section 70 is connected to the operation section 3 shown in FIG. 1, and the reading processing section 10 and the image processing section 20 are set based on the mode setting for reading the original set via the operation section 3. And the write processing unit 30. The reading processing unit 10, the image processing unit 20, and the methods of pulse width modulation, power modulation, and writing position modulation are known technologies, and are not special features in the present invention, and thus description thereof is omitted.

An image control signal will be described with reference to FIG. 5. The image control signal includes a main scanning synchronization signal XLSYNC which is a synchronization signal in the main scanning direction of the image, and a main scanning effective signal indicating an image valid period in the main scanning direction. A period signal XLGATE;
A sub-scanning effective period signal X indicating an image effective period in the sub-scanning direction
FGATE and a pixel clock CLK for synchronizing image data. The 2-bit image data Db from the image processing unit 20 is synchronized for each line by a main scanning synchronization signal XLSYNC, and a sub-scanning effective period signal XFGAT
The signal is output in synchronization with the pixel clock CLK while E and the sub-scanning effective period signal XLGATE are at “L” level.

The data delay unit 40 will be described in detail with reference to FIGS. The data delay unit 40 generates the data arrays Dc1 to Dc3 of three pixels in the main scanning direction by delaying the data Db processed by the image processing unit 20 in synchronization with the pixel clock CLK. Therefore, after performing various processes in the image processing unit 20, the image data Db converted into a 2-bit (quaternary) signal is input to the FF 41,
The output Dc1 of F41 becomes data obtained by delaying the image data Db by one pixel clock CLK.
It is input to F42 and delayed in synchronization with the pixel clock CLK. Similarly, image data Dc2 and Dc3 are obtained as outputs of the FFs 42 and 43.

The image data Dc1 to Dc of these three pixels
3 to the pattern detection unit 50, and
Then, the edge portion of a vertical line having a width of 2 dots or more and a vertical 1-dot line are detected from the pixel position indicated by Δ. At this time, the pixel Dc2 becomes the target pixel and the pixels Dc1 and Dc3
Are peripheral pixels.

Since the image data Db processed by the image processing section 20 is 2 bits, the density can be set to four levels, and the relationship with the actual image is 2 as shown in FIG. White when the bit combination is (0, 0),
At (0, 1), the gray level is “1”, at (1, 0), the gray level is “2” having a higher density than the gray level “1”, and at (1, 1), black. Here, as a combination of Dc1 to Dc3, since each dot can take four states, 4 × 4 × 4 = 6
There are four states. When all of these states are recognized and the data is converted and corrected by the data conversion unit 60 described later, 64
A conversion table of × 8 bits is required, and the scale of hardware increases.

Accordingly, in the present invention, as shown in FIG. 7, only the case where the peripheral pixels Dc1 and Dc3 are white or black and the pixel Dc2 of interest is halftone or white is detected as a pattern requiring correction. I do. Here, the meaning of each pattern will be described. First, two patterns Dd1 and Dd2 of {Dc1, Dc2, Dc3} = Dd1 = (0,0,1,0,0,0), Dd2 = (0,0,0,1,0,0) A vertical line (black vertical line) having a width of less than 1 dot is shown, and the only difference is the line thickness (1, 0) and (0, 1).

Dd31 = (1,1,0,0,0,0) Dd32 = (0,0,0,0,1,1) is a vertical line of 1 dot width or 2 dot width or more, respectively. The right edge and the left edge. Dd41 = (1,1,0,1,0,0) Dd42 = (0,0,0,1,1,1) is the right edge and left edge of a vertical line divided into two or more dots, respectively. It is.

Dd5 = (×, ×, 0,0, ×, ×), Dd6 = (×, ×, 0,1, ×, ×), Dd7 = (×, ×, 1,0, ×, ×) , Dd8 = (×, ×, 1, 1, ×, ×) The four patterns Dd5 to Dd8 do not correspond to the above-mentioned six patterns, and the patterns are different depending on the target pixel Dc2. Then, when the signals Dp1 to Dp8 shown on the right of each pattern match the pattern, it becomes “1”.

Further, Dd31 and Dd32, and Dd41 and Dd
By performing a logical sum on p42 and combining them into Dd3 and Dd4, respectively, only eight conversion tables are required, so that the conversion table is reduced to 、 ４ of the 4 × 4 × 4 conversion table.

Next, the detection pattern will be described. According to the present invention, correction is performed only when the peripheral pixels Dc1 and Dc3 are white or black and the target pixel Dc2 is halftone or black and correction is necessary. That is, if the target pixel Dc2 is originally white, the data cannot be further reduced. Therefore, the target pixel Dc2 is intended for the case of halftone or black.

The reason why the peripheral pixels Dc1 and Dc3 are white or black will be described. Since data without phase information is used as input data, in the case of halftone, the data is originally shifted to the right. It is unclear whether it should be moved to the left or to the left. Therefore, when one of the target pixel Dc2 and the peripheral pixels Dc1 and Dc3 is in halftone, it is unclear whether the two halftone data should be printed by shifting or printing apart from each other. However, the problem may be caused by the application. On the other hand, if the peripheral pixels Dc1 and Dc3 are limited to white or black, the phase information is irrelevant and printing is performed at full duty or no printing is performed. When the document is mainly considered, the left end portion and the right end portion of the image are often used, and the correction improves the reproducibility.

Dd31 and Dd32, Dd41 and Dp42
In the case of performing logical OR on Dd3 and Dd4, 1-bit phase data Ds is generated depending on whether the black pixel is on the right or on the left. Here, the relationship between the actual printing position and the image position is reversed depending on whether the developing method of the printer is the negative / positive method or the positive / positive method. = 0), and when the black pixel is on the right side, by setting it to the right (Ds = 1), an image with good print quality can be obtained at the left and right ends of the image.

In the case of the positive / positive system, the image is normally set to the right and set to the left when the black pixel is on the right side, so that an image with good print quality can be obtained at the left and right ends of the image. Can be Although not used in the present embodiment, when “center” can be selected by light emission timing control, the center (2 bits Ds = 2) is generated when one dot line is detected, so that good print quality is obtained. An image is obtained. FIG. 6 shows the relationship between the phase data Ds and the printing position.
This is shown in (2).

The operation of the pattern detecting section 50 in the case of the negative / positive method will be described below with reference to FIGS. In the pattern detection unit 50, the 6-bit data arrays Dc1 to Dc3 of three pixels obtained by delaying in the main scanning direction by the data delay unit 40 are the patterns Dd1 to Dd1 illustrated in FIG.
Data Dd1 to Dd8 depending on whether they match Dd8
, And the phase data Ds. Further, a pattern used for pattern detection is selected by the control unit 70.

In the pattern detection section 50, the data delay section 40
Outputs Dc1 to Dc3 are inverted (INV) and logical product (AN
D), pattern matching is performed by combining gates such as OR (OR). FIG. 8 shows a matching circuit for the bit pattern Dp1 when {Dc1, Dc2, Dc3} = Dp1 = (0, 0, 1, 0, 0, 0), and each bit Dc1 (1), (0) of Dc1 , Dc
2 lower bits Dc2 (0) and each bit Dc of Dc3
3 (1) and (0) are inverted by the INVs 51a to 51e, respectively, and when they match (0, 0, 1, 0, 0, 0), the outputs of the INVs 51a to 51e are all "1".
And then the outputs of INVs 51a-51e and Dc2
AND gate 5 which receives upper bit Dc2 (1) of
The output Dp1 of No. 2 is “1”. In this way, when each pattern is matched, the corresponding detection signal is “1”.
Becomes

FIG. 9 shows that Dd31 = (1, 1, 0, 0, 0, 0) and Dd32 = (0, 0, 0, 0, 1, 1) are detected by the pattern detectors 53a and 53b, respectively. 4 shows a matching circuit that generates a pattern detection signal Dd3 by ORing signals with an OR gate 54.

When the patterns do not match the patterns Dd1 to Dd4, the detection signals Dd1 to Dd4 are all "0", so that the output of the OR gate 57 to which the detection signals Dd1 to Dd4 are input as shown in FIG. 0 ". And
For example, in a matching circuit that detects a pattern of Dd5 = (×, ×, 0, 0, ×, ×), the target pixel D
The upper bit Dc2 (1) of c2 and the lower bit Dc2
By ORing (2) with the output of the OR gate 57 by the OR gate 58 and inverting the output of the OR gate 58 by the inverter 59, the detection signal Dd5 becomes "1" in the case of the pattern Dd5.

FIG. 11 shows that Dd42 = (0, 0, 0, 1, 1, 1) and Dd32 = (0, 0, 0, 0, 1, 1) are detected by the pattern detectors 55a and 55b, respectively. A circuit for performing OR operation of signals by an OR gate 56 to generate phase data Ds is shown.

Next, the data converter 60 will be described with reference to FIG. The data conversion unit 60 includes the pattern detection unit 5
The FF 61a connected to the 8-bit data bus of the control unit 70 in order to convert the data Dd1 to Dd8 corresponding to the pattern detected at 0 into data for actually performing modulation.
61h, 3-state buffers 62a-62h, and an address decoder 63.
Thus, data between 0 and 255 can be freely set as the writing density.

That is, addresses are assigned to the FFs 61a to 61h, and the address bus of the control unit 70 is decoded by the address decoder 63, and is ANDed with the write signal WR from the control unit 70.
When the control unit 70 writes to
Chip select Cs1-C corresponding to F61a-61h
In s8, the chip select for the FF in which data is to be written becomes 1.

A data bus of the control unit 70 is connected to the data inputs of the FFs 61a to 61h.
By setting s1 to Cs8 as the clock inputs of the FFs 61a to 61h, the data set by the control unit 70 is written. The signals Dd1 to Dd8 corresponding to the respective patterns detected by the pattern detector 50 are output to the three-state buffers 6 respectively.
By using it as the output enable signal of 2a to 62h, the data set in the corresponding FF as the light emission data of the matched pattern is made an effective output.

Then, based on the emission data set for each pattern by the data conversion section 60 and the phase data detected by the pattern detection section 50, a modulation scheme combining pulse width modulation and / or power modulation is used. Controls the light emission amount of the LD and the light emission start position.

The operation of the present invention will be described with reference to FIG. As mentioned above, the capital letter "I" in the alphabet
In the case of, the result of processing the input image as shown in FIG. 13A by the image processing unit 20 is as shown in FIG. 13B. In the case of the negative / positive developing method as in the conventional example, When the data is black (1, 1), the emission data is 8-bit maximum value 255, and when the data is halftone 2 (1, 0),
If the light emission data 170 and the light emission data for halftone 1 (0, 1) are set to 85, an output image as shown in FIG. 13C is obtained, and a thin portion tends to be interrupted and has no phase information. The output image is degraded at the left end portion of the image by printing at the fixed left position.

Therefore, in the present invention, this is detected by the pattern detection unit 50 to detect a pixel corresponding to the pattern shown in FIG. 7, and the data conversion unit 60 uses the light emission data for the pixel as light emission data by about 2 to 30%. Alternatively, the beam diameter can be made larger than usual by emitting light by pulse width modulation by raising it by a predetermined amount, so that it is possible to make the vertical line and the end of the image thicker, and as a result,
The image output as a copy is printed firmly as shown in FIG. 13D, so that reproducibility and visibility are improved. Further, the pixel corresponding to the left end is shifted to the right according to the phase data generated by the pattern detection unit 50. By printing the pixel corresponding to the right end as left-justified, the reproducibility can be further improved.

In the case of the positive / positive developing method, the printed portion becomes white on the output image. Therefore, a pixel corresponding to the pattern shown in FIG. 7 is detected, and the data conversion section 60 emits light to the pixel as light emission data. By emitting the light by pulse width modulation by reducing the data by about 2 to 30% or a predetermined amount, the beam diameter can be made smaller than usual, so that the vertical line and the end of the image can be made thicker. Become. Conversely, with respect to the phase, according to the phase data generated by the pattern detection unit 50, pixels corresponding to the left end are printed left-justified, and pixels corresponding to the right end are printed right-justified, so that reproducibility can be further improved. .
In the present embodiment, a digital copying machine is illustrated, but the present invention is also applicable to an image forming apparatus that forms an image using dots.

[0053]

As described above, according to the first aspect of the present invention, it is determined whether or not a vertical line having a width of one dot is determined based on a pattern of each multi-valued data of a target pixel and its neighboring pixels in the main scanning direction. Is detected, and the multi-valued data of the pixels constituting the vertical line is converted into print data so that the width of the detected vertical line becomes thicker. Also, it is possible to prevent a vertical line of 1 dot width of intermediate density from being interrupted.

According to the second aspect of the present invention, it is detected whether or not an edge of a vertical line having a plurality of dot widths is detected based on a pattern of each multi-valued data of a pixel of interest and peripheral pixels adjacent thereto in the main scanning direction. Since the multivalued data of the pixels constituting the edge is changed to the light emission data so that the edge is continuous with the vertical line, it is possible to prevent the edge portion of the vertical line having a plurality of dot widths from being interrupted in the multivalued image. .

According to the third aspect of the present invention, when the left and right pixels of the target pixel are white or black and the target pixel is halftone or white, the vertical line of one dot width or the vertical line of plural dot widths Therefore, it is possible to reduce the number of patterns to be detected, simplify the hardware configuration, and prevent occurrence of an abnormal image due to unnecessary correction.

According to the fourth aspect of the present invention, phase data for shifting the width is generated with respect to the multi-value data of the pixels constituting the edge of the vertical line having a plurality of dot widths, so that the light emission timing is controlled. Even when the phase data does not include multi-valued data, the edge portion of a line extending over a plurality of pixels and a single black dot line are made thicker, and furthermore, the blurring of characters is prevented without losing white, and an image with good visibility is obtained. be able to.

According to the fifth aspect of the present invention, when outputting to a negative / positive developing system printer, data conversion is performed so as to increase the amount of light emission. Can be.

According to the sixth aspect of the present invention, when outputting to a positive / positive development type printer, data conversion is performed so as to reduce the amount of light emission. Can be.

[Brief description of the drawings]

FIG. 1 is an external view showing a digital copying machine as an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram showing an image processing circuit of the digital copying machine shown in FIG.

FIG. 3 is a block diagram illustrating a data delay unit of FIG. 2 in detail;

FIG. 4 is a timing chart showing main signals in a data delay unit of FIG. 3;

FIG. 5 is an explanatory diagram showing an image control signal.

FIG. 6 is an explanatory diagram showing a relationship between 2-bit density data and print dots and a relationship between phase data and print positions.

FIG. 7 is an explanatory diagram illustrating a matching pattern detected by a pattern detection unit in FIG. 2;

FIG. 8 is a block diagram illustrating a pattern detecting unit of FIG. 2 in detail;

FIG. 9 is a block diagram illustrating a pattern detecting unit of FIG. 2 in detail;

FIG. 10 is a block diagram illustrating a pattern detection unit of FIG. 2 in detail;

FIG. 11 is a block diagram illustrating a phase data generation unit in the pattern detection unit of FIG. 2 in detail.

FIG. 12 is a block diagram illustrating a data conversion unit of FIG. 2 in detail;

FIG. 13 is an explanatory diagram showing thickening and width shifting processing of the image processing circuit of FIG. 2;

FIG. 14 is an explanatory view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 10 reading processing unit 20 image processing unit 30 writing processing unit 40 data delay unit 50 pattern detection unit 60 data conversion unit 70 control unit

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Claims (6)

[Claims] 1. An image forming apparatus for forming an image based on input image information, comprising: a vertical line having a width of one dot based on a pattern of multivalued data of a target pixel and neighboring pixels adjacent to the target pixel in a main scanning direction; Pattern detection means for detecting whether or not, the data conversion means for converting multi-valued data of the pixels constituting the vertical line to print data so that the width of the vertical line detected by the pattern detection means is wide, An image forming apparatus comprising: 2. The pattern detecting means further detects whether or not the target pixel is a vertical line edge having a plurality of dot widths based on a pattern of each multi-valued data of a target pixel and peripheral pixels adjacent thereto in the main scanning direction. 2. The image forming apparatus according to claim 1, wherein the data conversion unit further converts multi-valued data of pixels forming the edge into print data so that the edge is continuous with a vertical line. 3. The pattern detecting means according to claim 1, wherein the left and right pixels of the target pixel are white or black and the target pixel is halftone or white. The image forming apparatus according to claim 1, wherein the determination is made. 4. The method according to claim 1, wherein the pattern detection unit performs multi-valued data processing on pixels forming edges of a vertical line having a plurality of dot widths.
4. The image forming apparatus according to claim 2, wherein phase data for shifting the width is generated. 5. The data conversion unit according to claim 1, wherein the data conversion unit converts the light emission amount to increase when outputting to a negative / positive development type printer. Image forming device. 6. The data conversion device according to claim 1, wherein the data conversion unit converts the data so that the light emission amount is reduced when the data is output to a positive / positive development type printer. Image forming device.