JP2002113900A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus which adds phase data for controlling the thinning of a specific pattern part and the emission timing of a light emitting element. SOLUTION: A digital copy machine 1 comprises a first code converting section 50 for generating code data Dc from image data Db outputted from an image processing section 20 depending on density information, a second code converting section 60 for generating, as the image data Db, data corresponding to a specified matching pattern if an interesting pixel of the image data Db and the pattern of a plurality of pixels on the periphery thereof match any one of the edge part of the image or a plurality of specified patterns indicative of one dot line otherwise generating data corresponding to the density information of the image data Db, a section 90 for generating emission data Df from code data De selected from code data Dc and Dd at a code data switching section 80, and a section for modulating one or both of the emission time and emission quantity of a light emitting element wherein an image is formed by switching the emission timing of the light emitting element in the main scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus, and more particularly, to detecting a specific pattern in an image by pattern matching from multi-value data not including phase data for controlling the light emission timing of a light emitting element. The present invention relates to an image forming apparatus for thinning the specific pattern portion and adding phase data for controlling light emission timing.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus using a laser, such as a digital copying machine, a portion corresponding to a black portion of original data is irradiated with laser light, and toner is placed on the portion to form an image. A negative / positive (N / P) process for forming is common.

Since the beam diameter of the laser beam is usually larger than one theoretical dot, the N / P process of irradiating the image portion with a laser beam to form that portion as an image usually produces one dot. The black line is reproduced thickly and firmly.

[0004] Therefore, although it is strong against breaks in lines, it is conversely reproduced thicker than the black lines of the original,
Also, the white one dot line becomes thinner, and the reproducibility of the image tends to decrease. Particularly, in a so-called grandchild copy in which a sheet copied by a digital copying machine is used again as a manuscript, the above-mentioned phenomenon appears largely.

As another drawback of the electrophotographic method, there is a difference in reproducibility between a vertical line and a horizontal line. In general, a vertical line is reproduced firmly and thicker than a horizontal line. As a result, horizontal lines tend to be thinner than the original if they are aligned with the vertical lines when determining the imaging conditions, and conversely, vertical lines tend to be thicker than the original if the imaging conditions are adjusted to the horizontal lines. There is a problem that
This has contributed to the difficulty in determining the imaging conditions.

Accordingly, the applicant of the present invention first converts binary image data input from a scanner or an external device into multi-valued data by power modulation, and writes the binary image data into multi-valued data. A step of determining a multi-value level of the target pixel from at least two pixels before and after the target pixel. Has been proposed (see JP-A-5-75816).

In other words, this technique prevents the non-image portion from being collapsed by determining the density of the target pixel with reference to the target pixel and two or more pixels before and after the target pixel with respect to the binary image data. The reproducibility of one dot line is improved.

Conventionally, in an image information processing system for supplying a signal to a recording apparatus for modulating the area of a colored image occupying one pixel based on a signal representing a multi-valued image of ternary or higher, in an image information processing system, On the other hand, an image information processing method has been proposed in which a recording start position corresponding to the target pixel is controlled based on the density of an adjacent pixel (see Japanese Patent Application Laid-Open No. 6-89338).

That is, according to this technique, the printing start position of the target pixel is determined from the relationship between the target pixel and its adjacent pixels in the multi-valued image. The reproducibility of the edge part of the image is improved.

[0010]

However, in the above-mentioned prior art, there is a need for improvement in forming a multi-valued image with high accuracy.

That is, the technique described in Japanese Patent Laid-Open No. 5-75816 corrects the density of only binary image data to improve the reproducibility of one dot line. I didn't.

The technique described in Japanese Patent Application Laid-Open No. 6-89338 discloses a method of reproducing a multi-valued image by shifting a pixel of interest to an adjacent pixel and printing a thin line divided into two or more pixels or an edge portion of the image. 1 pixel fine line,
In addition, no consideration is given to the correction of the line width when the thicknesses of the vertical line and the horizontal line are different, and there is a need for improvement in improving the image quality.

According to the first aspect of the present invention, the first code data generating means generates code data from a plurality of bits of image data indicating only density information in accordance with the density information. When the pattern of the pixel of interest and its surrounding pixels matches any one of a plurality of specific patterns indicating an edge portion of the image or one dot line, the second code data generating means Data corresponding to the pattern is generated as code data, and when the data does not match the specific pattern, the second code data generating means generates data corresponding to the density information of the image data of a plurality of bits as code data. A data switch for switching and outputting code data output from the first code data generation means and the second code data generation means. The light emission data generation means generates light emission data from the code data output from the light emission means, and the modulation means emits one or both of the light emission time and the light emission amount of the light emitting element according to the light emission data generated by the light emission data generation means. And modulating the light emission timing of the light emitting element in the main scanning direction in any of the main scanning directions to form an image. The density of the pixel of interest is changed by differentiating the light emission data generated by the generated code data and the code data generated by the second code data generation means. In the case of code data matching a specific pattern, Make the emission data different from the normal case, and make sure that the edge of a line that spans multiple pixels or one black dot line becomes too thick. Thereby preventing the vertical line, to prevent the different thickness of the horizontal lines, and its object is to provide an image forming apparatus for improving the image quality of the formed image.

According to a second aspect of the present invention, the light emission data generating means generates light emission data for correcting the light emission amount in accordance with the density with respect to the code data generated by the first code data generation means, For the code data generated by the code data generating means, the code corresponding to the density does not match the specific pattern, and for the code corresponding to the density, the light emission data for correcting the light emission amount according to the density is generated, and the specific pattern is generated. By generating light emission data for reducing the amount of emitted light for the matched code, correction is performed such that the amount of emitted light is smaller than usual for the code that matches the specific pattern, and the correction is performed over a plurality of pixels. In addition to preventing line edges and black one-dot lines from becoming too thick, preventing vertical and horizontal lines from differing in thickness, the image quality of the formed image is reduced. And its object is to provide an image forming apparatus is further improved.

According to a third aspect of the present invention, the second code data generating means includes a plurality of identification codes in which a pattern of a pixel of interest of a plurality of bits of image data and a plurality of pixels around the pixel of interest indicates an edge portion or one dot line of the image. When any one of the patterns matches the pattern, the phase data for controlling the light emission timing of the modulating means is generated in accordance with the specific pattern that matches the pattern. On the other hand, the light emission time and / or the light emission amount of the light emitting element are modulated, and the light emission timing is also controlled to shift the density-changed data to the right, left, or center, so that the edge portion of the line extending over a plurality of pixels or the black portion is adjusted. In addition to appropriately preventing one dot line from becoming too thick, it is more important to prevent the vertical and horizontal lines from differing in thickness. And its object is to provide an image forming apparatus to further improve the image quality of properly preventing, the formed image.

According to a fourth aspect of the present invention, the second code data generating means includes a delay means for delaying a plurality of bits of image data indicating only density information in the main scanning direction and an output from the delay means in the main scanning direction. A pattern table that detects a specific pattern using a plurality of pixels, and a data generation unit that generates data corresponding to a pattern of a detection result of the pattern table, the pattern table includes:
As a specific pattern, when the pixel on the left and right of the target pixel is a combination of white or black and the target pixel is a halftone or black pixel, it is detected as an edge portion or a one-dot line of the image to be density corrected. By doing so, the number of patterns to be detected is reduced to simplify the hardware configuration, and the occurrence of abnormal images due to unnecessary correction is prevented, and image formation with better reproducibility is performed. It is another object of the present invention to provide an image forming apparatus that further improves the image quality of a formed image.

[0017]

According to an aspect of the present invention, there is provided an image forming apparatus comprising: first code data generating means for generating code data from a plurality of bits of image data indicating only density information in accordance with the density information; When the pattern of the target pixel of the multi-bit image data indicating only the density information and the pattern of a plurality of pixels around the target pixel matches any one of a plurality of specific patterns indicating an edge portion of the image or one dot line, A second code data generating means for generating data corresponding to the specific pattern matched as code data, and generating data corresponding to the density information of the plurality of bits of image data as code data when the data does not match the specific pattern; Disconnecting the code data output from the first code data generation means and the second code data generation means. A data switching means for recombinant output,
Light emission data generation means for generating light emission data from the code data switched and output by the data switching means,
Either or both of the light emission time and the light emission amount of the light emitting element are modulated in accordance with the light emission data generated by the light emission data generating means, and the light emission timing of the light emitting element in the main scanning direction is changed in any of the main scanning directions. A light emitting data generating means, wherein the light emitting data generating means includes a code data generated by the first code data generating means and a light emitting data generated by the second code data generating means. The above object is achieved by making the generated light emission data different from the generated code data.

According to the above configuration, the first code data generating means generates code data from the multi-bit image data indicating only the density information in accordance with the density information, and determines the code data of the target pixel of the multi-bit image data. When a pattern of a plurality of pixels around the pattern matches any one of a plurality of specific patterns indicating an edge portion of an image or a one-dot line, the second code data generation unit responds to the matched specific pattern. The data is generated as code data, and when the data does not match the specific pattern, the second code data generating means generates data corresponding to the density information of the image data of a plurality of bits as code data,
The light emission data generation means generates light emission data from code data output from the data switching means for switching and outputting code data output from the first code data generation means and the code data output from the second code data generation means. The modulation means modulates one or both of the light emission time and the light emission amount of the light emitting element according to the light emission data generated by the means, and adjusts the light emission timing of the light emitting element in the main scanning direction in any of the main scanning directions. When the image is formed by controlling the switching also in the direction, the light emission data generation means generates the light emission data generated by the code data generated by the first code data generation means and the code data generated by the second code data generation means. Because of the difference, the density of the pixel of interest is changed, and if the code data matches a specific pattern, Is different from the normal case, it is possible to prevent the edge of a line extending over a plurality of pixels and a black dot line from becoming too thick, and to prevent the vertical and horizontal lines from having different thicknesses. And the image quality of the formed image can be improved.

In this case, for example, as described in claim 2, the light emission data generation means corrects the light emission amount according to the density of the code data generated by the first code data generation means. Light emission data is generated, and for the code data generated by the second code data generation means, for a code corresponding to the density that does not match the specific pattern, the light emission amount is corrected according to the density. Light emission data may be generated, and light emission data for correcting a light emission amount to be reduced for a code that matches the specific pattern may be generated.

According to the above arrangement, the light emission data generation means generates light emission data for correcting the light emission amount in accordance with the density with respect to the code data generated by the first code data generation means, and generates the second code. For the code data generated by the data generating means, for a code corresponding to the density without matching the specific pattern, light emission data for correcting the amount of emitted light according to the density was generated, and the code matched the specific pattern. Since emission data is generated for the code to reduce the amount of emitted light, correction is made so that the amount of emitted light is smaller than usual for codes that match a specific pattern, and the edge of a line that spans multiple pixels is corrected. It is possible to more appropriately prevent the part and the black one-dot line from becoming too thick, and prevent the thickness of the vertical line and the horizontal line from being different from each other. The image quality of the image can be further improved.

For example, as described in claim 3, the second code data generating means is arranged so that a pattern of a pixel of interest of the plurality of bits of image data and a plurality of pixels around the pixel of interest is an edge portion of the image or one of the plurality of pixels. When any one of a plurality of specific patterns indicating a dot line matches, the phase data for controlling the light emission timing of the modulating means may be generated according to the specific pattern matched.

According to the above arrangement, the second code data generating means is arranged such that the pattern of the pixel of interest of the multi-bit image data and the pattern of the plurality of pixels around the target pixel are a plurality of specific patterns indicating an edge portion or one dot line of the image. When any one of the patterns matches, the phase data for controlling the light emission timing in the modulating means is generated according to the specific pattern matched. By modulating the light emission time and / or light emission amount of the light emitting element, and controlling the light emission timing, the data whose density has been changed is shifted to the right, left, or center, and the edge portion of a line extending over a plurality of pixels or one black dot It is possible to prevent the line from becoming too thick, and to prevent the vertical and horizontal lines from having different thicknesses. Can be a layer appropriately prevent the image quality of a formed image can be further improved.

Further, for example, as set forth in claim 4, the second code data generating means includes a delay means for delaying a plurality of bits of image data representing only the density information in a main scanning direction; A pattern table for detecting a specific pattern by using a plurality of pixels in the main scanning direction from the output of the means, and a data generating means for generating data corresponding to the pattern of the detection result of the pattern table; The table includes, as the specific pattern, an edge portion of the image to be subjected to the density correction when the right and left pixels of the target pixel are a combination of white or black, and the target pixel is a halftone or black pixel. Alternatively, it may be detected as one dot line.

According to the above arrangement, the second code data generation means delays the plurality of bits of image data indicating only the density information in the main scanning direction, and outputs a plurality of image data in the main scanning direction from the output of the delay means. A pattern table that detects a specific pattern using pixels, and a data generation unit that generates data corresponding to a pattern of a detection result of the pattern table are provided. When the left and right pixels are a combination of white or black and the target pixel is a halftone or black pixel, the pixel is detected as an edge portion or a one-dot line of the image to be subjected to density correction. The hardware configuration can be simplified by reducing the number of patterns to be performed, and the occurrence of abnormal images due to unnecessary correction Can be prevented by performing a more excellent image formation reproducibility can be further improved image quality of the formed inexpensively image.

[0025]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 15 show an embodiment of the image forming apparatus according to the present invention. FIG. 1 shows a digital camera to which the embodiment of the image forming apparatus according to the present invention is applied. FIG. 1 is an external perspective view of a copying machine.

In FIG. 1, a digital copying machine 1 is provided with a document table 2 on which an original is placed and read, and an openable and closable pressure plate 3 for holding the document on the document table 2. On the front surface, an operation display unit 4 for displaying a reading mode, a copy magnification, an operation content for an operator, and the like is provided. The digital copying machine 1 includes a paper feed unit 5 on the lower side, and a paper discharge unit 6 on the left side.

Although not shown, the digital copying machine 1 has a built-in mechanism and control unit as the digital copying machine 1 such as an exposure optical system, a paper feeding and conveying system, a developing system, a fixing system, and a paper discharging system. Thus, the operation as the digital copying machine 1 is realized.

That is, in the digital copying machine 1, in a state where the original is placed on the original platen 2, the pressure plate 3 is closed and the original is brought into close contact with the original platen 2, reading conditions and When the copy key is set and the start key is pressed, the original is read by an illumination system and an imaging optical system (not shown) according to the instruction on the operation display unit 4. After performing various corrections on the read image data, the digital copying machine 1 irradiates a beam with a laser diode (hereinafter, referred to as LD) as a light emitting element in a writing system based on the image data, An electrostatic latent image is formed on the photoconductor.

Thereafter, the digital copying machine 1 forms a copy image on a sheet fed from the sheet feeding unit 5 in accordance with an instruction from the operation display unit 4 through a normal electrophotographic process.

As shown in FIG. 2, the digital copying machine 1
It includes a reading processing unit 10, an image processing unit 20, a writing processing unit 30, and a control unit 40. The writing processing unit 30 includes a first code conversion unit (first code data generation unit) 50, a second code Conversion unit (second code data generation unit) 60, phase detection unit 70, code data switching unit (data switching unit) 8
0 and a light emission data generation unit (light emission data generation means) 90.

The read processing unit 10 performs various correction processes such as shading correction on image data read at 600 dpi by a CCD line sensor (not shown), and obtains 8 bits (256 gradations) for each pixel as image data Da. Output to the image processing unit 20.

The image processing section 20 performs MTF correction, scaling processing, and the like on the image data Da input from the reading processing section 10 to correct the image quality, and then performs a 2-bit (four gradation) multi-value The data is converted to data Db and output to the write processing unit 30. The multi-value data Db is image data indicating only density information.

The write processing unit 30 converts the image data Db from the image processing unit 20 into a code corresponding to the density information by the first code conversion unit 50, and outputs 3-bit code data Dc
Is output to the code data switching unit 80. Further, the writing processing unit 30 detects whether or not the multi-value data Db matches a specific pattern such as an edge portion of an image or a one-dot line in the second code conversion unit 60. Is converted to a code corresponding to the matching pattern. If there is no pattern matching the specific pattern, the code is converted to a code corresponding to the density information, and the 3-bit code data Dd is output to the code data switching unit 80. .

The phase data detecting section 70 generates phase data Ds for switching the writing position from right or left in the main scanning direction.

The code data switching section 80 switches which of the code data Dc and Dd is to be used based on the control signal from the control section 40, and outputs it as the code data De.

The light emission data generation section 90 converts the code data De input from the code data switching section 80 into 8-bit light emission data Df.
Based on the bit light emission data Df and the phase data generated by the phase data detection unit 70, a modulation unit (modulation means) (not shown) modulates the light emission time and / or the light emission power of the LD, thereby obtaining the image data in the image data. By changing the writing density and the writing start position for the edge portion and the thin line portion, writing to a photoconductor (not shown) is performed at 256 gradations and 600 dpi.

The control section 40 is connected to the operation display section 4 and, based on the mode setting for reading the original set on the operation display section 4, etc., the reading processing section 10 and the image processing section 2
0 and the write processing unit 30 are controlled.

The reading processing unit 10, the image processing unit 20, and the methods of pulse width modulation, power modulation, and writing position modulation are the same as in the ordinary digital copying machine 1.

The first code converter 50 is configured as shown in FIG. 3, and has two flip-flops (F
F) 51, 52 are provided.

The first code conversion section 50 performs bit conversion. A second code conversion section 60 described later outputs 3-bit data as code data, and the emission data generation section 90 converts the 3-bit code data. In order to perform the process of converting the data into the 8-bit light emission data Df, the 2-bit multi-valued image data is converted into 3-bit code data in accordance with these processes, and the data phase is adjusted with the second code conversion unit 60. .

That is, as shown in FIG. 4, after the image processing unit 20 performs various image processing, the FF 51
The image data Db converted into a bit (quaternary) signal is input in synchronization with the clock CLK, and the FF 51 delays the image data Db by one clock and converts the data Db1 into an FF.
52. In FIG. 4, XLGATE
Is a signal indicating an image valid period in the main scanning direction.

The FF 52 is, as shown in FIG.
Db1 inputted in synchronization with clock CLK from
Is further delayed and bit conversion is performed. That is, a signal fixed to 1 bit 0 is input to the FF 52 in addition to the data Db 1, and the FF 52 outputs 3 bits according to the density information as data obtained by adding 1 bit 0 to the top of the image data Db. It is converted as bit code data Dc and output to the code data switching unit 80.

As shown in FIG. 5, the second code conversion section 60 includes a data delay section (delay means) 61, a pattern table 62, and a code generation section (data generation means) 63. , The image data Db is delayed in the scanning direction, and data arrays Dg1 to Dg of three pixels in the main scanning direction are delayed.
3 is generated and output to the pattern table 62.

That is, the data delay unit 61 includes three flip-flops (FF) 101 to 1 as shown in FIG.
03, the data Db processed by the image processing unit 20 is delayed in synchronization with the clock CLK to generate a data array of three pixels in the main scanning direction.

After various image processing is performed by the image processing unit 20, the FF 101 receives the image data Db converted into a 2-bit (quaternary) signal, and as shown in FIG. Is output to the pattern table 62 and is output to the FF 102 while the data Dg1 is delayed by one clock.

The FF 102 is, as shown in FIG.
The data Dg1 input from the D.01 is delayed in synchronization with the clock CLK, the data Dg2 delayed by one clock is output to the pattern table 62, and the FF 103
Output to

Further, as shown in FIG. 7, the FF 103 delays the data Dg2 input from the FF 102 in synchronization with the clock CLK, and outputs the data Dg3 delayed by one clock to the pattern table 62.

The pattern table 62 stores the image data Dg
A specific pattern such as an edge portion or a one-dot line of an image of 1 to Dg3 is detected, and detection result signals Dh1 to Dh64 are output to the code generation unit 63. This detection result signal Dh1
To Dh64 indicate which pattern each pattern matches, and the phase data detection unit 70 generates the phase data Ds indicating whether the writing position is performed from the right or from the left, as described above. Do.

The pattern table 62 is used for detecting an edge portion of an image or a one-dot line from a portion indicated by a triangle in FIG. At this time, the data Dg2 becomes the target pixel, and the data Dg1 and the data Dg3 become the peripheral pixels. The image data Db processed by the image processing unit 20 is, as described above,
Since it is 2-bit data, the density can take four levels, and the relationship with the actual image is as shown in FIG. That is, when the combination of two bits of the image data Db input from the image processing unit 20 is (0, 0), the combination of two bits of white and image data Db is:
In the case of (0, 1), the combination of two bits of halftone 1 and image data Db is (1, 0), and in the case of (1, 0), halftone 2 having a higher density than halftone 1 and image data Db When the combination of two bits is (1, 1), it is black.

Therefore, as a combination of the data Dg1 to Dg3, each dot can take four states.
× 4 × 4, as shown in FIG. 9, there are 64 states, and in FIG. 9, ΔDg1, Dg2, Dg
3｝ = (0,0,0,0,0,0), (0,1,0,
The pattern of (0, 0, 0)... Indicates one dot line, and one of them is selected. Then, according to the selected pattern, the signals Dh1 to Dh illustrated at the right end
One of the 64 becomes “1”.

Further, the pattern table 62 generates phase data as shown in FIG. 8B depending on whether the black pixel is on the right or on the left. That is, usually
When the black pixels are on the right side in the left-justified state (data 0), by shifting the data to the right side (data 1), an image with good print quality can be obtained at the leading and trailing ends of the image. Although not used in the present embodiment, if the center can be selected by controlling the light emission timing of the LD, the center (data 2) is generated when one dot line is detected, so that good print quality can be obtained. Image is obtained.

Referring again to FIG.
Is 6-bit code data D according to the detection result signals Dh1 to Dh64 input from the pattern table 62.
d is generated and output to the code data switching unit 80.

As shown in FIG. 10, the code generation unit 63 includes 64 three-state buffers STB1 to SSTB.
64, and generates code data based on the detection result signals Dh1 to Dh64 corresponding to the patterns detected by the pattern table 62. The code generator 63 outputs a detection result signal Dh of each pattern detected by the pattern table 62.
1 to Dh64 in three-state buffers STB1 to SST, respectively.
By using it as an output enable signal of B64, code data of a matched pattern is generated. That is, the inputs of the three-state buffers STB1 to SSTB64 are fixed to 6-bit code data corresponding to each pattern, and the detection result signals Dh1 to Dh64 of each pattern detected by the pattern table 62 are converted to the three-state buffers STB1 to SSTB64. Of the corresponding pattern,
The outputs of the state buffers STB1 to SSTB64 become valid, and the corresponding data is output from the code generation unit 63 as code data Dd.

The code data switching section 80 shown in FIG.
Is composed of a selector 81, as shown in FIG. 11, which includes 3-bit code data Dc corresponding to the density information from the first code converter 50 and And a mode setting signal from the control unit 40.

The code data switching section 80 uses the selector 81 to correct the density of one dot line and the end of the image in accordance with the mode setting signal from the control section 40. The generated 6-bit code data Dd is selected and output as the code data De to the light emission data generation unit 90. When the correction of the density of one dot line and the end of the image is not performed, the first code conversion unit 50 is used.
Is selected and output to the light emission data generation unit 90 as code data De.

The light emission data generation unit 90 shown in FIG.
As shown in FIG. 2, a flip-flop (FF) 201 to 264 connected to the data bus of the control unit 40, three-state buffers STB101 to STB164, an address decoder 271, a decoder 272, and the like are provided. Code data De1 to De to be input
The data is converted into data for causing the LD to emit light based on the data 64. That is, the light emission data generation unit 90 controls the
Allows you to freely set the data you want to convert.

More specifically, the light emission data generation unit 90 outputs
The addresses are assigned to F201 to FF264, and the address of the control unit 40 is decoded by the address decoder 271 and ANDed with the write signal WR from the control unit 40. When writing is performed, each of the FFs 201 to FF
Among the chip selects Cs1 to Cs8 corresponding to H.264, the chip select for the FFs 201 to 264 for writing data becomes “1”. FF201-FF2
Since the data bus of the control section 40 is connected to the data input of the chip select Cs1 to Cs64,
Is input to the FFs 201 to 264 as a clock input, so that the data set by the control unit 40 is
264. Then, the code data switching unit 8
The signals De1 to De64 corresponding to the respective code data De1 to De64 converted by 0 are converted from 6 bits to 64 bits by the decoder 272, and are used as output enable signals of the three-state buffers STB101 to STB164, whereby each code is converted. The data set in the corresponding FF 201 to FF 264 as the light emission data Df of is used as an effective output.

Next, the operation of the present embodiment will be described. As shown in FIG. 13, the digital copying machine 1 reads the original 300 set on the original platen 2 by the reading processing unit 10 and performs various correction processes such as shading correction on the read image data. The image data Da is output to the image processing unit 20 in 8 bits (256 gradations) for each pixel.

In this image reading control, as shown in FIG. 13, XLS which is a synchronization signal in the main scanning direction of the image is used.
YNC, XLGAT indicating the image valid period in the main scanning direction
E, XFGATE indicating the image valid period in the sub-scanning direction, and CLK for synchronizing image data. The image data Db is synchronized for each line by a synchronization signal XLSYNC in the main scanning direction, and an image valid period signal XFGATE in the sub-scanning direction and an image valid period signal X in the main scanning direction.
While LGATE is at “L” level, the pixel clock CLK
Are output from the image processing unit 20 shown in FIG.

When the image data of the image of the original 300 read by the reading processing unit 10 is, for example, a one-dot vertical line or a horizontal line, the digital copying machine 1 outputs the input image as shown in FIG. (Image data Da) to the image processing unit 20
14B, two bits (4 bits) as shown in FIG.
(Gray scale) is input to the write processing unit 30.

If the light emission data Df is set to the maximum value 255 of 8 bits when this data is black (1, 1),
Normally, the beam diameter is larger than one pixel so that the solid black portion is completely filled. Therefore, the copy line tends to be thicker than the line on the original 300,
Even if the light emission data Df is the same, as a characteristic of the electrophotographic method,
If the vertical and horizontal lines are actually output as copies,
As shown in FIG. 14C, the vertical line tends to be a thick copy output image.

However, the digital copying machine 1 according to the present embodiment uses the pattern table 62 of the second code conversion unit 60 to specify the pattern of one dot line (0, 0, 1, 1, 0,
0) or (0, 0, 1, 0, 0, 0), the light emission data generation unit 90 causes the light emission data D
The light emission data Df for the pixel is 200 to 2 as f.
By lowering it to about 20, the LD is made to emit light by pulse width modulation, and the beam diameter is made longer than usual.

Therefore, the vertical line can be thinned,
As shown in FIG. 14D, the image output as a copy becomes almost the same as the actual original 300. As a result, reproducibility can be improved, and image quality can be improved without affecting portions other than vertical lines.

In addition, in the case of the leading end and the trailing end of the image of the original 300, in addition to the same problem as the one dot line, as shown in FIGS. When two data to be attached and reproduced are converted into data having no phase information and written, the emission timing is fixed to the right or left (or the center),
In the case of fixed to the left, it is the tip of the image. In the case of fixed to the right,
At the end of the image, the lines are split. In the case where the density of the halftone portion is low and the interval is wide, the divided portions shown in FIG.
As shown in (c), one line is originally output in the form of a divided line. If the density of the halftone is high and the interval is small, the line will be buried and become a thick line. It may cause a loss of performance.

However, in the digital copying machine 1 of the present embodiment, the pattern table 62 of the second code conversion unit 60
Is the pattern (1, 1, 1,
1, 0, 0), (0, 0, 1, 1, 1, 1), (1,
When a pixel corresponding to (1, 1, 0, 0, 0) or (0, 0, 1, 0, 1, 1) is detected, the light emission data generation unit 9
By performing the density correction at 0 and lowering the density than normal, the line of the copy tends to be thicker than the original and the difference between the thickness of the vertical line and the horizontal line is corrected. In accordance with the phase data generated in step 70, a pixel corresponding to the front end is right-aligned, and a pixel corresponding to the rear end is added left-aligned phase data Ds, and LD based on the added data of the phase data Ds is added. The light emission timing is controlled for printing.

Therefore, as shown in FIG.
The image of the document 300 can be output with good reproducibility.

As described above, in the digital copying machine 1 of the present embodiment, the first code converter 50 generates the code data Dc from the multi-bit image data indicating only the density information in accordance with the density information. When the pattern of the pixel of interest of the image data of a plurality of bits and a plurality of pixels around the pixel of interest matches any one of a plurality of specific patterns indicating an edge portion of the image or one dot line, the second code conversion section 6
0 generates data corresponding to the matched specific pattern as code data Dd. When the data does not match the specific pattern, the second code conversion unit 60 sets the data corresponding to the density information of the multi-bit image data. Is generated as code data Dd, the code data Dc output from the first code conversion unit 50 and the code data Dc output from the second code conversion unit 60 are switched from the code data De output from the code data switching unit 80 for switching and output. 90 generates light emission data Df, and a modulation unit (not shown) modulates one or both of the light emission time and the light emission amount of the light emitting element according to the light emission data Df generated by the light emission data generation unit 90; When controlling the light emission timing of the light emitting element in the main scanning direction in any of the main scanning directions, an image is formed. , Emission data generating unit 90 has made different emission data Df generated in the generated code data Dd of code data Dc and the second code conversion section 60 produced in the first code converter 50.

Therefore, the density of the target pixel is changed, and in the case of code data that matches a specific pattern, the emission data Df is made different from the normal case, so that the edge portion of a line extending over a plurality of pixels or the black It is possible to prevent one dot line from becoming too thick, prevent the vertical line and the horizontal line from being different in thickness, and improve the image quality of the formed image.

The digital copier 1 of the present embodiment
The light emission data generation unit 90 generates the light emission data Df for correcting the light emission amount according to the density for the code data Dc generated by the first code conversion unit 50, and generates the light emission data Df by the second code conversion unit 60. For the code data Dd, for the code Dd that does not match the specific pattern and for the code Dd corresponding to the density, the light emission data Df for correcting the light emission amount according to the density is generated, and the code Dd that matches the specific pattern is generated. On the other hand, light emission data Df for reducing and correcting the light emission amount is generated.

Accordingly, for the code Dd that matches the specific pattern, correction is made so that the amount of emitted light is smaller than usual, so that the edge portion of a line extending over a plurality of pixels or one black dot line becomes too thick. Can be more appropriately prevented, and the thickness of the vertical and horizontal lines can be prevented from being different, and the image quality of the formed image can be further improved.

Further, the digital copying machine 1 of the present embodiment
Indicates that the second code conversion unit 50 determines that the pattern of the pixel of interest in the multi-bit image data and a plurality of pixels around it matches any one of a plurality of specific patterns indicating an edge portion or a dot line of the image. , And generates phase data for controlling the light emission timing in the modulation section according to the specific pattern matched.

Therefore, for the pixel located at the edge portion of the line and one dot line, the light emission time and / or the light emission amount of the light emitting element are modulated, and the light emission timing is also controlled to change the data whose density is changed to the right. Alternatively, it is possible to more appropriately prevent the edge portion of the line extending over a plurality of pixels or the black one-dot line from becoming too thick by shifting to the left or the center, and to confirm that the thicknesses of the vertical line and the horizontal line are different. This can be prevented more appropriately, and the image quality of the formed image can be further improved.

The digital copier 1 of the present embodiment
The second code conversion unit 60 uses a data delay unit 61 that delays, in the main scanning direction, a plurality of bits of image data indicating only density information in the main scanning direction, and a plurality of pixels in the main scanning direction from the output of the data delay unit 61. A pattern table 62 for detecting a specific pattern, and a code generation unit 63 for generating data corresponding to a pattern of a detection result of the pattern table 62
When the pattern table 62 has a specific pattern in which the left and right pixels of the target pixel are a combination of white or black and the target pixel is a halftone or black pixel, the density correction target Is detected as an edge portion of an image or a dot line.

Therefore, the number of patterns to be detected can be reduced to simplify the hardware configuration.
The occurrence of an abnormal image due to unnecessary correction can be prevented, and an image with better reproducibility can be formed, and the image quality of the formed image can be further improved at low cost.

Although the invention made by the inventor has been specifically described based on the preferred embodiments, the invention is not limited to the above-described embodiment, and various modifications may be made without departing from the gist of the invention. It goes without saying that it is possible.

[0077]

According to the image forming apparatus of the present invention, the first code data generating means generates code data from a plurality of bits of image data indicating only density information in accordance with the density information. When the pattern of the pixel of interest of the image data of the plurality of bits and a plurality of pixels around the pixel coincides with any one of a plurality of specific patterns indicating an edge portion of the image or one dot line, the second code data generation means When the data does not match the specific pattern, the second code data generating means generates the data corresponding to the density information of the multi-bit image data. Data generated by the first code data generating means and the second code data generating means. The light emission data generation means generates light emission data from the code data output from the data switching means, and the modulation means determines whether the light emission time of the light emitting element or the light emission amount in accordance with the light emission data generated by the light emission data generation means. When the image data is formed by modulating both or both of them and controlling the light emission timing of the light emitting element in the main scanning direction to be switched to any one of the main scanning directions, the light emission data generation means generates the first code data generation data. Since the light emission data generated by the code data generated by the means and the code data generated by the second code data generation means are different, the density of the pixel of interest is changed, and the code data that matches the specific pattern is changed. In the case of, the emission data is made different from the normal case, and the edge portion of a line extending over a plurality of pixels and the black one dot line are thickened. It is possible to prevent the Risugiru, vertical lines, it is possible to prevent that different thicknesses of the horizontal line, it is possible to improve the image quality of the formed image.

According to the image forming apparatus of the present invention, the light emission data generation means corrects the light emission amount according to the density for the code data generated by the first code data generation means. And for the code data generated by the second code data generating means, for the code corresponding to the density that does not match the specific pattern, generates the emission data for correcting the amount of emitted light according to the density. Then, for the code that matches the specific pattern, the light emission data for reducing the emission light amount is generated, so the code that matches the specific pattern is corrected so that the emission light amount is smaller than usual. In addition, it is possible to more appropriately prevent the edge portion of a line extending over a plurality of pixels and a single black dot line from becoming too thick, and to prevent the vertical lines and horizontal lines from having different thicknesses. Can be stopped, the image quality of a formed image can be further improved.

According to the image forming apparatus of the third aspect, the second code data generating means is arranged such that the pattern of the target pixel of the multi-bit image data and the pattern of the plural pixels around the target pixel are the edge portion of the image or one dot. If any one of the plurality of specific patterns indicating a line matches one of the patterns, phase data for controlling the light emission timing of the modulating means is generated in accordance with the specific pattern that matches the pattern. For the pixels located in the line, the light emission time and / or the light emission amount of the light emitting element are modulated, and the light emission timing is also controlled to shift the density-changed data to the right, left, or center, thereby forming a line extending over a plurality of pixels. Edge and black one dot line can be prevented from becoming too thick, and vertical and horizontal lines can be prevented. The thickness is different can be further appropriately prevent the image quality of a formed image can be further improved.

According to the image forming apparatus of the present invention, the second code data generating means delays a plurality of bits of image data indicating only density information in the main scanning direction, A pattern table for detecting a specific pattern using a plurality of pixels in the main scanning direction from the output,
Data generation means for generating data according to the pattern of the detection result of the pattern table,
When the pattern table has a specific pattern in which the right and left pixels of the target pixel are a combination of white or black and the target pixel is a halftone or black pixel, the edge portion or one dot of the image to be density corrected Since it is assumed to be detected as lines, the number of patterns to be detected can be reduced to simplify the hardware configuration, and the occurrence of abnormal images due to unnecessary correction can be prevented. The image quality of the formed image can be further improved at a low cost by forming a better image.

[Brief description of the drawings]

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

FIG. 2 is a circuit block diagram of the digital copying machine shown in FIG. 1;

FIG. 3 is a detailed circuit block diagram of a first code converter of FIG. 2;

FIG. 4 is a timing chart showing processing timing of image data in a first code conversion unit in FIG. 3;

FIG. 5 is a detailed circuit block diagram of a second code converter of FIG. 2;

FIG. 6 is a detailed circuit block diagram of a data delay unit in FIG. 5;

FIG. 7 is a timing chart showing processing timing of image data in the data delay unit of FIG. 6;

8A is a diagram illustrating a relationship between density data generated by the pattern table of FIG. 5 and actual print dots, and FIG. 8B is a diagram illustrating a relationship between phase data generated by the pattern table and an actual print position. (B).

9 is a diagram showing a relationship between a combination of data generated by a data delay unit in FIG. 5 and a pattern selected in a pattern table.

FIG. 10 is a detailed circuit block diagram of a code generation unit in FIG. 5;

FIG. 11 is an internal circuit block diagram of a code data switching unit in FIG. 2;

FIG. 12 is a detailed circuit block diagram of a light emission data generation unit in FIG. 2;

FIG. 13 is a diagram showing a relationship between each signal and image data at the time of reading the original shown in FIGS. 1 and 2;

14 shows the output (b) of the image processing unit of FIG. 2 for the input image (a) in the case of a one-dot vertical line and a horizontal line, a conventional copy output (c), and a copy by the digital copying machine of FIG. The figure which shows output (d).

FIG. 15 shows the output (b) of the image processing unit in FIG. 2 for the input image (a) in the case of the leading edge and the trailing edge of the original image, the conventional copy output (c), and the digital copying machine in FIG. The figure which shows copy output (d).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 digital copying machine 2 platen 3 pressure plate 4 operation display unit 5 paper feed unit 6 paper discharge unit 10 read processing unit 20 image processing unit 30 write processing unit 40 control unit 50 first code conversion unit 51, 52 flip-flop (FF) ) 60 second code conversion unit 61 data delay unit 62 pattern table 63 code generation unit 70 phase detection unit 80 code data switching unit 81 selector 90 emission data generation unit 101-103 flip-flop (FF) STB1-SSTB64 3-state buffer 201- H.264 flip-flop (FF) STB101 to STB164 3-state buffer 271 Address decoder 272 Decoder 300 Document

Claims (4)

[Claims] A first code data generating means for generating code data from a plurality of bits of image data indicating only the density information in accordance with the density information; a target pixel of the multi-bit image data indicating only the density information; When a pattern of a plurality of pixels surrounding the pattern matches any one of a plurality of specific patterns indicating an edge portion of an image or a dot line, data corresponding to the matched specific pattern is generated as code data, When the data does not match a specific pattern, data corresponding to the density information of the plurality of bits of image data is generated as code data.
Code data generating means, data switching means for switching and outputting code data output from the first code data generating means and the second code data generating means, and the code switching and outputting by the data switching means A light emitting data generating means for generating light emitting data from the data, and modulating one or both of a light emitting time and a light emitting amount of the light emitting element according to the light emitting data generated by the light emitting data generating means; And a modulating means for switching the light emission timing to any of the main scanning directions, wherein the light emission data generation means generates the light emission timing by the first code data generation means. The light emission data to be generated differs between the code data and the code data generated by the second code data generation means. An image forming apparatus comprising. 2. The light emission data generating means generates light emission data for correcting the light emission amount in accordance with a density with respect to the code data generated by the first code data generation means,
For the code data generated by the second code data generating means, for code corresponding to the density that does not match the specific pattern, light emission data for correcting the light emission amount according to the density is generated, The image forming apparatus according to claim 1, wherein light emission data for reducing and correcting a light emission amount is generated for a code that matches the specific pattern. 3. The method according to claim 2, wherein the pattern of the pixel of interest of the plurality of bits of image data and a plurality of pixels surrounding the pixel of interest are any of a plurality of specific patterns indicating an edge portion of an image or a dot line. 3. The image forming apparatus according to claim 1, wherein when the pattern matches, the phase data for controlling the light emission timing in the modulation unit is generated in accordance with the matched specific pattern. 4. 4. The image processing apparatus according to claim 1, wherein said second code data generating means includes: a delay means for delaying, in the main scanning direction, a plurality of bits of image data indicating only said density information; A pattern table that detects a specific pattern by using the pattern table; and a data generation unit that generates data corresponding to the pattern of a detection result of the pattern table. The pattern table includes the target pattern as the specific pattern. When the right and left pixels are a combination of white or black and the pixel of interest is a halftone or black pixel, the pixel is detected as an edge portion or a dot line of the image to be corrected for density. The image forming apparatus according to any one of claims 1 to 3, wherein